fswiki.us - User contributions [en]

Sensors

2021-11-16T22:57:14Z

RealHumanBean: /* Air Temperature Sensors */

Sensors measure physical properties, and convert their measurements into electrical signals to be captured by the data logger and used for running the vehicle, diagnosing the vehicle, verifying that the vehicle is running properly, and/or helping to tune the vehicle.
==Sensor Types==
===Sensing location/movement of vehicle===
These sensors are used to tell where the vehicle is, and how it is moving. Dataloggers often have some or more of these sensors built in. With these sensors, where they are mounted on the car may change how useful the data is. For instance, you may find that you want to mount them as close to the center of gravity as possible.
====Accelerometer====
Measures its acceleration in one or more axes. This may or may not be the actual acceleration of the vehicle, depending on how it's mounted.
====Gyroscope====
Measures its angular velocity (change in an angle over time) on one or more axes. Again, you'll probably want these axes to line up with those of the vehicle.
====Magnetometer====
Measures the strength and direction of the magnetic field. Useful for measuring the yaw of the vehicle.
====IMU====
Standing for Inertial Measurement Unit, it measures orientation, velocity, and acceleration in all three axes, utilizing accelerometers, gyroscopes, and magnetometers.
====GPS Receivers====
Obtains GPS data. This is usually used for logging the position of the car, so that you can see where the car is going and compare lines through corners.
===Sensing Movement of a Single Component===
====Hall Effect Sensors====
Detect the presence of a magnetic field. These are typically switches, that are either on or off (i.e., not analog). These are most commonly used to detect and measure rotation, e.g. of a gear. Unlike a VR sensor, they require an external magnetic force.
====Variable Reluctance Sensors====
Known also as VR sensors, they detect a change in the magnetic field. Unlike hall effect sensors, they do not require an external magnetic field, so many OEMs use them for cam and crank position sensors.
====Potentiometers====
Variable resistor ladders that measure movement. The can be used as driver controls (e.g., for adjusting radio volume), or in linear form for measuring shock travel (among other uses).
====Rotary Position Sensors====
These act as more accurate rotary potentiometers. Often they are contactless, meaning they last much longer and for many more cycles than potentiometers do. These are useful as pedal position sensors and steering angle sensors.
====Knock Sensors====
Sensors that detect engine knocking. These will bolt directly to the engine block, and will usually come with the engine. there are a buncha different kinds of knock sensors - i'll try to get something sketched out here this week -simon
===O2 Concentration Sensors===
O2 sensors measure how much oxygen is in the exhaust. This allows you to figure out the air-fuel ratio of the engine. Narrowband O2 sensors can only tell you if you are rich, lean, or at the stoichiometric efficiency of the engine, whereas wideband O2 sensors tell you your exact air-fuel ratio with much more accuracy. Narrowband O2 sensors are usually used by the OEMs for troubleshooting catalytic converters, but most racecars use wideband O2 sensors to help tune the engine.

A wideband O2 sensor needs a wideband controller to connect to an ECU. Sometimes this is embedded inside the ECU, other times it has to be purchased separately.
===Pressure Sensors===
====Liquid Pressure Sensors====
====Air Pressure Sensors====
===Strain Gauges===
Strain Gauges measure the strain on an object—the deformation due to the forces traveling through it. They have a trace that curves back and forth, which elongates or contracts slightly as the object stretches or compresses. This elongation alters the resistance of the strain gauge, which can be measured with a wheatstone bridge and an amplifier.
===Temperature Sensors===
====Liquid Temperature Sensors====
At minimum, most engines will have a single coolant temperature sensor to measure the temperature of the water in the cooling circuit. This is reported to the engine control unit and is used to determine when the engine cooling fans should be turned on. Additional liquid temperature sensors include oil temperature sensors to monitor the health and performance of the lubrication system (the oil-coolant heat exchanger on most vehicles should reduce this as a concern) and additional coolant temperature sensors to assess radiator performance.

====Air Temperature Sensors====
During testing, the team should record the ambient weather conditions (humidity, any rainfall past or present, visibility, etc.). On the vehicle itself, an air temperature sensor mounted on the intake plenum can be used to adjust the fuel injector flow rate to compensate for temperature driven air density changes. This should be considered an almost essential powertrain sensor for engine tuning. Engine exhaust temperature sensors in the exhaust headers can also provide information on the vehicles performance for design evaluation; if two header temperatures differ significantly, that indicates that there is an issue with the spark/fuel flow/air flow/leakage for one of the cylinders.

====Infrared Temperature Sensors====
==Signal Types==
===Analog Sensors===
====2-Wire====
2-Wire sensors act like a rheostat, a variable resistor. Because of this, the two wires are almost always interchangeable. One wire is wired to the device input, with a pullup resistor to 5V (this pullup may be internal to your ECU) and the other wire goes to ground.
====3-Wire====
3-wire sensors take power and ground and send a output signal, usually a voltage that corresponds linearly to whatever the sensor measures. The wires are almost never interchangeable. Because they have a power input, they do not need a pullup resistor. Some 3-wire sensors, like the CBR600RR coolant temperature sensor, are actually 2-wire sensors with an internal pullup resistor.
===Digital Sensors===
====Pulsed====
Pulsed sensors send a series of digital pulses where the frequency of the pulses represents the measurement value. Commonly seen in shaft speed sensors.
====PWM====
PWM sensors vary the width of pulses at a fixed frequency to represent the measurement value. A simple analog filter can allow a PWM sensor to be approximated into an analog signal.
====Serial====
Some "smart" sensors transmit their measurement value(s) over a [[Communication Protocols|communication protocol]] such as CAN Bus, I2C, or SPI. This allows multiple values to be transmitted without additional wiring.
[[Category:Data Acquisition]]

==Some Common Applications==
===Driver Training===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type''' 
|-
|GPS
|Visualize and compare driving lines, visual aid for displaying data on an overlay of the course
|GPS
|-
|Throttle position sensor (TPS)
|Visualize and compare driver's throttle pedal control
|Rotary position sensor or potentiometer
|-
|Accelerator pedal position sensor (APPS)
|Visualize and compare driver's throttle pedal control
|Rotary position sensor or potentiometer
|-
|Brake sensor
|Visualize and compare driver's braking
|Liquid pressure sensor, rotary position sensor or potentiometer
|-
|Steering angle sensor
|Visualize and compare driver's steering
|Rotary position sensor or potentiometer
|}

===Aerodynamics===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Air pressure sensor
|Validating aero simulations
|Air pressure sensor
|-
|Air speed sensor
|Calibrating downforce calculations for headwind
|Pitot tube
|-
|Shock length sensor
|Determining downforce at front vs. rear
|Linear potentiometer
|}

===Brakes===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Brake pressure sensor (front and rear)
|Validate braking system design, determine brake bias
|Liquid pressure sensor
|-
|Brake light switch
|Turn on brake light when brakes are applied
|Liquid pressure switch
|-
|Brake rotor temperature sensor (front and rear)
|Validate brake rotor design
|IR temperature sensor
|}

===Chassis===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Strain gauges
|Validating chassis stiffness
|Strain gauge
|}

===Powertrain: Internal Combustion===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Cam position
|Determine ignition/fuel timing
|VR sensor
|-
|Crank position
|Determine ignition/fuel timing and determine engine speed (aka RPM)
|VR sensor
|-
|Accelerator pedal position sensor (APPS)
|Required for ETC
|Rotary position sensor or potentiometer
|-
|Throttle position sensor (TPS)
|Required for ETC, helps determine how much fuel the engine needs
|Rotary position sensor or potentiometer
|-
|Manifold/intake air pressure (MAP/IAP)
|Determines how much fuel the engine needs
|Air pressure sensor 
|-
|Manifold/intake air temperature (MAT/IAT)
|Calibrates AFR for the temperature of the air
|Air temperature sensor
|-
|Coolant temperature (CLT)
|Verify that the engine isn't about to blow up, tune engine for cold start
|Liquid temperature sensor
|-
|Coolant pressure
|Verify that the cooling system works, diagnosing problems
|Liquid pressure sensor
|-
|Fuel pressure
|Verify that the fuel system works, diagnosing problems
|Liquid pressure sensor
|-
|Wideband O2
|Tuning the car, diagnosing misfires (AFR will appear higher if a misfire is occurring)
|O2 sensor
|-
|Gear sensor
|Display what gear the transmission is to the driver
|Rotary potentiometer?
|-
|Neutral switch
|Tell the driver if they're in neutral or not
|Switch
|-
|Vehicle speed sensor (at transmission output)
|Verify differential performance, calculating what gear you're in
|Hall effect sensor
|}

===Powertrain: Electric===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Motor position
|Determines what angle the motor is at so the inverter can time the AC phases
|Resolver, encoder, or hall effect sensor
|-
|Motor temperature
|Make sure motor doesn't overheat
|Temperature sensor
|-
|Coolant temperature (CLT)
|Make sure motor and/or motor controller don't overheat
|Liquid temperature sensor
|-
|Coolant pressure
|Make sure there's no leak, make sure water pump is operating correctly
|Liquid pressure sensor
|}

===Drivetrain===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Rear wheel speed sensors
|Verify differential/torque vectoring performance, traction control
|Hall effect, VR, inductive proximity sensor
|}

===Suspension===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Tire pressure
|Verify tire performance, suspension tuning
|Wireless air pressure sensor
|-
|Tire temperature
|Verify tire performance, suspension tuning (even camber if multiple temperature readings per tire)
|Surface or IR temperature sensor
|-
|Shock length sensor
|Suspension tuning
|Linear potentiometer
|-
|Strain gauges
|Verify forces on suspension members
|Strain gauge
|-
|IMU
|Suspension tuning
|IMU
|}

Sensors

2021-11-16T22:53:27Z

RealHumanBean: /* Liquid Temperature Sensors */

Sensors measure physical properties, and convert their measurements into electrical signals to be captured by the data logger and used for running the vehicle, diagnosing the vehicle, verifying that the vehicle is running properly, and/or helping to tune the vehicle.
==Sensor Types==
===Sensing location/movement of vehicle===
These sensors are used to tell where the vehicle is, and how it is moving. Dataloggers often have some or more of these sensors built in. With these sensors, where they are mounted on the car may change how useful the data is. For instance, you may find that you want to mount them as close to the center of gravity as possible.
====Accelerometer====
Measures its acceleration in one or more axes. This may or may not be the actual acceleration of the vehicle, depending on how it's mounted.
====Gyroscope====
Measures its angular velocity (change in an angle over time) on one or more axes. Again, you'll probably want these axes to line up with those of the vehicle.
====Magnetometer====
Measures the strength and direction of the magnetic field. Useful for measuring the yaw of the vehicle.
====IMU====
Standing for Inertial Measurement Unit, it measures orientation, velocity, and acceleration in all three axes, utilizing accelerometers, gyroscopes, and magnetometers.
====GPS Receivers====
Obtains GPS data. This is usually used for logging the position of the car, so that you can see where the car is going and compare lines through corners.
===Sensing Movement of a Single Component===
====Hall Effect Sensors====
Detect the presence of a magnetic field. These are typically switches, that are either on or off (i.e., not analog). These are most commonly used to detect and measure rotation, e.g. of a gear. Unlike a VR sensor, they require an external magnetic force.
====Variable Reluctance Sensors====
Known also as VR sensors, they detect a change in the magnetic field. Unlike hall effect sensors, they do not require an external magnetic field, so many OEMs use them for cam and crank position sensors.
====Potentiometers====
Variable resistor ladders that measure movement. The can be used as driver controls (e.g., for adjusting radio volume), or in linear form for measuring shock travel (among other uses).
====Rotary Position Sensors====
These act as more accurate rotary potentiometers. Often they are contactless, meaning they last much longer and for many more cycles than potentiometers do. These are useful as pedal position sensors and steering angle sensors.
====Knock Sensors====
Sensors that detect engine knocking. These will bolt directly to the engine block, and will usually come with the engine. there are a buncha different kinds of knock sensors - i'll try to get something sketched out here this week -simon
===O2 Concentration Sensors===
O2 sensors measure how much oxygen is in the exhaust. This allows you to figure out the air-fuel ratio of the engine. Narrowband O2 sensors can only tell you if you are rich, lean, or at the stoichiometric efficiency of the engine, whereas wideband O2 sensors tell you your exact air-fuel ratio with much more accuracy. Narrowband O2 sensors are usually used by the OEMs for troubleshooting catalytic converters, but most racecars use wideband O2 sensors to help tune the engine.

A wideband O2 sensor needs a wideband controller to connect to an ECU. Sometimes this is embedded inside the ECU, other times it has to be purchased separately.
===Pressure Sensors===
====Liquid Pressure Sensors====
====Air Pressure Sensors====
===Strain Gauges===
Strain Gauges measure the strain on an object—the deformation due to the forces traveling through it. They have a trace that curves back and forth, which elongates or contracts slightly as the object stretches or compresses. This elongation alters the resistance of the strain gauge, which can be measured with a wheatstone bridge and an amplifier.
===Temperature Sensors===
====Liquid Temperature Sensors====
At minimum, most engines will have a single coolant temperature sensor to measure the temperature of the water in the cooling circuit. This is reported to the engine control unit and is used to determine when the engine cooling fans should be turned on. Additional liquid temperature sensors include oil temperature sensors to monitor the health and performance of the lubrication system (the oil-coolant heat exchanger on most vehicles should reduce this as a concern) and additional coolant temperature sensors to assess radiator performance.

====Air Temperature Sensors====
====Infrared Temperature Sensors====
==Signal Types==
===Analog Sensors===
====2-Wire====
2-Wire sensors act like a rheostat, a variable resistor. Because of this, the two wires are almost always interchangeable. One wire is wired to the device input, with a pullup resistor to 5V (this pullup may be internal to your ECU) and the other wire goes to ground.
====3-Wire====
3-wire sensors take power and ground and send a output signal, usually a voltage that corresponds linearly to whatever the sensor measures. The wires are almost never interchangeable. Because they have a power input, they do not need a pullup resistor. Some 3-wire sensors, like the CBR600RR coolant temperature sensor, are actually 2-wire sensors with an internal pullup resistor.
===Digital Sensors===
====Pulsed====
Pulsed sensors send a series of digital pulses where the frequency of the pulses represents the measurement value. Commonly seen in shaft speed sensors.
====PWM====
PWM sensors vary the width of pulses at a fixed frequency to represent the measurement value. A simple analog filter can allow a PWM sensor to be approximated into an analog signal.
====Serial====
Some "smart" sensors transmit their measurement value(s) over a [[Communication Protocols|communication protocol]] such as CAN Bus, I2C, or SPI. This allows multiple values to be transmitted without additional wiring.
[[Category:Data Acquisition]]

==Some Common Applications==
===Driver Training===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type''' 
|-
|GPS
|Visualize and compare driving lines, visual aid for displaying data on an overlay of the course
|GPS
|-
|Throttle position sensor (TPS)
|Visualize and compare driver's throttle pedal control
|Rotary position sensor or potentiometer
|-
|Accelerator pedal position sensor (APPS)
|Visualize and compare driver's throttle pedal control
|Rotary position sensor or potentiometer
|-
|Brake sensor
|Visualize and compare driver's braking
|Liquid pressure sensor, rotary position sensor or potentiometer
|-
|Steering angle sensor
|Visualize and compare driver's steering
|Rotary position sensor or potentiometer
|}

===Aerodynamics===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Air pressure sensor
|Validating aero simulations
|Air pressure sensor
|-
|Air speed sensor
|Calibrating downforce calculations for headwind
|Pitot tube
|-
|Shock length sensor
|Determining downforce at front vs. rear
|Linear potentiometer
|}

===Brakes===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Brake pressure sensor (front and rear)
|Validate braking system design, determine brake bias
|Liquid pressure sensor
|-
|Brake light switch
|Turn on brake light when brakes are applied
|Liquid pressure switch
|-
|Brake rotor temperature sensor (front and rear)
|Validate brake rotor design
|IR temperature sensor
|}

===Chassis===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Strain gauges
|Validating chassis stiffness
|Strain gauge
|}

===Powertrain: Internal Combustion===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Cam position
|Determine ignition/fuel timing
|VR sensor
|-
|Crank position
|Determine ignition/fuel timing and determine engine speed (aka RPM)
|VR sensor
|-
|Accelerator pedal position sensor (APPS)
|Required for ETC
|Rotary position sensor or potentiometer
|-
|Throttle position sensor (TPS)
|Required for ETC, helps determine how much fuel the engine needs
|Rotary position sensor or potentiometer
|-
|Manifold/intake air pressure (MAP/IAP)
|Determines how much fuel the engine needs
|Air pressure sensor 
|-
|Manifold/intake air temperature (MAT/IAT)
|Calibrates AFR for the temperature of the air
|Air temperature sensor
|-
|Coolant temperature (CLT)
|Verify that the engine isn't about to blow up, tune engine for cold start
|Liquid temperature sensor
|-
|Coolant pressure
|Verify that the cooling system works, diagnosing problems
|Liquid pressure sensor
|-
|Fuel pressure
|Verify that the fuel system works, diagnosing problems
|Liquid pressure sensor
|-
|Wideband O2
|Tuning the car, diagnosing misfires (AFR will appear higher if a misfire is occurring)
|O2 sensor
|-
|Gear sensor
|Display what gear the transmission is to the driver
|Rotary potentiometer?
|-
|Neutral switch
|Tell the driver if they're in neutral or not
|Switch
|-
|Vehicle speed sensor (at transmission output)
|Verify differential performance, calculating what gear you're in
|Hall effect sensor
|}

===Powertrain: Electric===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Motor position
|Determines what angle the motor is at so the inverter can time the AC phases
|Resolver, encoder, or hall effect sensor
|-
|Motor temperature
|Make sure motor doesn't overheat
|Temperature sensor
|-
|Coolant temperature (CLT)
|Make sure motor and/or motor controller don't overheat
|Liquid temperature sensor
|-
|Coolant pressure
|Make sure there's no leak, make sure water pump is operating correctly
|Liquid pressure sensor
|}

===Drivetrain===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Rear wheel speed sensors
|Verify differential/torque vectoring performance, traction control
|Hall effect, VR, inductive proximity sensor
|}

===Suspension===

{| class="wikitable"
|-
|'''Sensor name'''
|'''Use'''
|'''Sensor type'''
|-
|Tire pressure
|Verify tire performance, suspension tuning
|Wireless air pressure sensor
|-
|Tire temperature
|Verify tire performance, suspension tuning (even camber if multiple temperature readings per tire)
|Surface or IR temperature sensor
|-
|Shock length sensor
|Suspension tuning
|Linear potentiometer
|-
|Strain gauges
|Verify forces on suspension members
|Strain gauge
|-
|IMU
|Suspension tuning
|IMU
|}

Cooling

2021-09-05T22:57:15Z

RealHumanBean: /* Getting that cooling Power */

More than 50% of energy used in combustion goes into heat[citation needed]. Heat is also generated by the turbulence of the air in the intake and cylinder, as well as friction from the engine's internals. A system is needed to keep the engine within it's operational temperature range.
=Theory=
Cooling systems are designed to dissipate the unwanted thermal energy. Systems are often designed around heat exchangers (HEXs), allowing for efficient exchange of heat from a hot fluid to a cooler one. There are three main methods of heat transfer;
* Conduction: Heat transfer over a temperature differential without motion between the materials
* Convection: Heat transfer over a temperature differential with fluid motion between the materials
* Radiation: Heat transfer due to by energy emitted from the unstable nature of a hot material (shitty definition, but the best I have)
** Heat transfer in the form of electromagnetic radiation emitted by bodies above absolute 0 (wikipedia says its a function of distributing entropy, not sure we're gonna get a simple, and easy answer here)
A heat exchanger (HEX) is normally designed to optimize the heat transfer between two fluids using conduction and convection. The most common HEX is an water to air cooler, meaning it transfers heat between the hot water and the cooler air. These HEXs have a few distinct characteristics, full metal construction, thin metal fins in the streamwise direction, water inlets on top and bottom, with air inlets on the front and back. The metal construction is due to a low conductive heat transfer coefficient within the metal in addition to a low specific heat. These factors allow the metal rapidly conduct heat from the hotter internal water channels to the cooler metal fin tips. Aluminum is nearly universally used in automotive radiators. While materials such as copper may notionally provide more cooling due to higher thermal conductivity, the thermal resistance of aluminum sheet metal is so low that the heat transfer from the water circuit to the air is limited by the convective coefficients. Aluminum also is light and strong as fins or sheets. The fin structure is to maximize convection heat transfer by increasing the surface area the air flows over. The convection heat transfer coefficient is also a function of the airspeed passing the fin, allowing for 'forced convection' where a fan and or vehicle speed is used to impart an inlet speed to the system.Behavior(function?) of radiators vary heavily based upon water channel sizes, fin spacing, and a plethora of other characteristics.
For a more detailed understanding of theory, any heat transfer textbook such as ''Incropera and Dewitt ''will serve. ''Kays and London'''s heat exchanger text is invaluable as a practical reference. It includes heat transfer coefficients for various fin and tube geometries. It is possible to measure the geometry of your radiator's fins, determine what type of fin geometry you are using, and then look up the appropriate set of coefficients for a rather robust heat exchanger model.

=Cooling Power=
The amount of thermal power that the engine puts into the water has to be the same as the thermal power the radiator dissipates ''at steady state''.
==Needed Cooling Power==
The rule of thumb is that 1/3 of the power you put into the engine in the form of fuel flow turns into heat. 1/3 becomes the power that turns the wheels and the last third comes out the exhaust or gets dissipated over the air [citation needed]. This ratio means that the power the radiator has to dissipate is approximately the same as the power sent to the wheels.

You have to keep in mind though that you don't drive full throttle all the time, so you have to average the engine power over the hole stint. You can do that for example by measuring the fuel consumption of your engine. I don't know how accurate that it though, because I've never done it. Also don't mind power peaks, like on a long straight, because the thermal capacity of your coolant is so big that it compensates that easily.[citation needed, just bc yours was big enough, doesnt mean everyone's is]

Finding average power output of the engine is one way to determine necessary cooling power for the engine. This can be accomplished by measuring fuel consumption or engine torque/vehicle velocity (P = FxV).
==Getting that cooling Power==
There are a couple of things that influence how much power the cooling system has. The best way to do this is likely to build a script in MATLAB/python and do parametric sweeps to see how your system behaves with various modifications. Some examples are:
* Radiator size: This is that you want to get right. It has by far the biggest impact. Radiator size is not created equal as lower temperature water will be cooled less than high temperature water. Therefore, increasing the width of the radiator is more economical with respect to weight than increasing the length.<brdata-attributes="" />
* Water flow rate: Basically neglegible. If you switch from a average sized pump to one with twice the flow rate you just get 1 or 2 Watt of additional power. Let's say the air has 30°C and your water 100°C when it enters the radiator and 95°C at the exit of it. Now you swap pumps and the bigger one makes the water leave the radiator at 97°C. You now have increased the temperature difference between the air and water from 67.5K to 68.5K or by 1.5%. This means your cooling power also increased by 1.5%. Measuring water flow rate is invaluable, but it is essential to understand that flow rate depends both on engine RPM and pressure rise imposed by the radiator and the rest of the cooling circuit, as these are generally centrifugal pumps. By contrast, an automotive oil pump is a fixed displacement type that will always deliver a certain oil volumetric flowrate provided it is being fed oil. [citation needed]<brdata-attributes="" />
** Not basically negligible, just diminishing returns, if you have 0 water flow rate, you'll get close to 0 cooling no matter what else you do, if you have a properly sized water pump and swap to a bigger one, you'll see limited gains. If the water flow is too low, you won't be able to send enough heat from the engine to the radiator. Upgrading a water pump can be a serious investment in time and resources. Note that the water pumps on the stock engine are designed to pump coolant for an unrestricted engine running at significantly higher power, and these engines are designed to be run hard if they are for supersports like the 600rr. Therefore, it is unlikely but certainly possible that upgrading the water pump is a good step for your team.<brdata-attributes="" />
* Airflow: A front wing could make the air go over your radiator and make the engine go boom.
** Also shrouds are said to do stuff.
** Fan - forced convection. Generally, fans are ideally not running during normal operation. Because the margin between running temperature (about 90C) and disaster (100C) is so tight, the fans might have to run fairly aggressively especially on a hot day when chaining autocross laps. A tight seal between fan shroud and the radiator is key to avoid leakage. Spacing between the fan and radiator is also key: you want a uniform pressure difference across the radiator to achieve a uniform flow rate.<brdata-attributes="" />
* The angle of the radiator: You can angle it to about 30° (some even say 45°) relative to the airflow without any significant loss in cooling power. [citation needed]<brdata-attributes="" />
* single pass v double pass

=Radiator Types=
cross flow / downflow radiator, radiator form factors, and why we all use them
=Radiator Placement=
======Side======
======Rear======
======Multiple======
=System Design=
must be cooled w water only(IC and EV) or oil(EV). 
no additives 
Must be able to pass 45 deg tilt test w no leaks
===Hosing===
type and sizing
===Routing===
keep it short and straight
===Filling and Bleeding===
===Catch Can===
just crush a 1L beer and spray paint the can black, its what we all did, not gonna get any lighter or cheaper.
===Data and Data collection===
see [[:Category:Data Acquisition|Data Acquisition]]

=Other applications=
===Brake cooling===

* Convective
** ducting
** theyre spinning hot disks, they have natural convection
* Radiation

===Oil cooling===
Many engines have an OEM oil/water heat exchanger. From my experience with the 600rr, these are very compact and well integrated with the original powertrain system. Most teams use what is close to the manufacturer's recommended engine oil and the water coolant should be a perfectly fine substitute for the antifreeze solution on the OEM bikes.

why you would want to cool oil
* If it boils or denatures bad things happen - Novotny
* thanks, lol, just a placeholder, isnt meant to be a question, poor phrasing on my end - simon
* all good, I was confused :')

===Intercooler===
===Driver cooling===
lmao

[[Category: Internal Combustion]]

Cooling

2021-09-05T22:56:46Z

RealHumanBean: /* Getting that cooling Power */

More than 50% of energy used in combustion goes into heat[citation needed]. Heat is also generated by the turbulence of the air in the intake and cylinder, as well as friction from the engine's internals. A system is needed to keep the engine within it's operational temperature range.
=Theory=
Cooling systems are designed to dissipate the unwanted thermal energy. Systems are often designed around heat exchangers (HEXs), allowing for efficient exchange of heat from a hot fluid to a cooler one. There are three main methods of heat transfer;
* Conduction: Heat transfer over a temperature differential without motion between the materials
* Convection: Heat transfer over a temperature differential with fluid motion between the materials
* Radiation: Heat transfer due to by energy emitted from the unstable nature of a hot material (shitty definition, but the best I have)
** Heat transfer in the form of electromagnetic radiation emitted by bodies above absolute 0 (wikipedia says its a function of distributing entropy, not sure we're gonna get a simple, and easy answer here)
A heat exchanger (HEX) is normally designed to optimize the heat transfer between two fluids using conduction and convection. The most common HEX is an water to air cooler, meaning it transfers heat between the hot water and the cooler air. These HEXs have a few distinct characteristics, full metal construction, thin metal fins in the streamwise direction, water inlets on top and bottom, with air inlets on the front and back. The metal construction is due to a low conductive heat transfer coefficient within the metal in addition to a low specific heat. These factors allow the metal rapidly conduct heat from the hotter internal water channels to the cooler metal fin tips. Aluminum is nearly universally used in automotive radiators. While materials such as copper may notionally provide more cooling due to higher thermal conductivity, the thermal resistance of aluminum sheet metal is so low that the heat transfer from the water circuit to the air is limited by the convective coefficients. Aluminum also is light and strong as fins or sheets. The fin structure is to maximize convection heat transfer by increasing the surface area the air flows over. The convection heat transfer coefficient is also a function of the airspeed passing the fin, allowing for 'forced convection' where a fan and or vehicle speed is used to impart an inlet speed to the system.Behavior(function?) of radiators vary heavily based upon water channel sizes, fin spacing, and a plethora of other characteristics.
For a more detailed understanding of theory, any heat transfer textbook such as ''Incropera and Dewitt ''will serve. ''Kays and London'''s heat exchanger text is invaluable as a practical reference. It includes heat transfer coefficients for various fin and tube geometries. It is possible to measure the geometry of your radiator's fins, determine what type of fin geometry you are using, and then look up the appropriate set of coefficients for a rather robust heat exchanger model.

=Cooling Power=
The amount of thermal power that the engine puts into the water has to be the same as the thermal power the radiator dissipates ''at steady state''.
==Needed Cooling Power==
The rule of thumb is that 1/3 of the power you put into the engine in the form of fuel flow turns into heat. 1/3 becomes the power that turns the wheels and the last third comes out the exhaust or gets dissipated over the air [citation needed]. This ratio means that the power the radiator has to dissipate is approximately the same as the power sent to the wheels.

You have to keep in mind though that you don't drive full throttle all the time, so you have to average the engine power over the hole stint. You can do that for example by measuring the fuel consumption of your engine. I don't know how accurate that it though, because I've never done it. Also don't mind power peaks, like on a long straight, because the thermal capacity of your coolant is so big that it compensates that easily.[citation needed, just bc yours was big enough, doesnt mean everyone's is]

Finding average power output of the engine is one way to determine necessary cooling power for the engine. This can be accomplished by measuring fuel consumption or engine torque/vehicle velocity (P = FxV).
==Getting that cooling Power==
There are a couple of things that influence how much power the cooling system has. The best way to do this is likely to build a script in MATLAB/python and do parametric sweeps to see how your system behaves with various modifications. Some examples are:
* Radiator size: This is that you want to get right. It has by far the biggest impact. Radiator size is not created equal as lower temperature water will be cooled less than high temperature water. Therefore, increasing the width of the radiator is more economical with respect to weight than increasing the length. 
* Water flow rate: Basically neglegible. If you switch from a average sized pump to one with twice the flow rate you just get 1 or 2 Watt of additional power. Let's say the air has 30°C and your water 100°C when it enters the radiator and 95°C at the exit of it. Now you swap pumps and the bigger one makes the water leave the radiator at 97°C. You now have increased the temperature difference between the air and water from 67.5K to 68.5K or by 1.5%. This means your cooling power also increased by 1.5%. Measuring water flow rate is invaluable, but it is essential to understand that flow rate depends both on engine RPM and pressure rise imposed by the radiator and the rest of the cooling circuit, as these are generally centrifugal pumps. By contrast, an automotive oil pump is a fixed displacement type that will always deliver a certain oil volumetric flowrate provided it is being fed oil. [citation needed] 
** Not basically negligible, just diminishing returns, if you have 0 water flow rate, you'll get close to 0 cooling no matter what else you do, if you have a properly sized water pump and swap to a bigger one, you'll see limited gains. If the water flow is too low, you won't be able to send enough heat from the engine to the radiator. Upgrading a water pump can be a serious investment in time and resources. Note that the water pumps on the stock engine are designed to pump coolant for an unrestricted engine running at significantly higher power, and these engines are designed to be run hard if they are for supersports like the 600rr. Therefore, it is unlikely but certainly possible that upgrading the water pump is a good step for your team. 
* Airflow: A front wing could make the air go over your radiator and make the engine go boom.
** Also shrouds are said to do stuff.
** Fan - forced convection. Generally, fans are ideally not running during normal operation. Because the margin between running temperature (about 90C) and disaster (100C) is so tight, the fans might have to run fairly aggressively especially on a hot day when chaining autocross laps. A tight seal between fan shroud and the radiator is key to avoid leakage. Spacing between the fan and radiator is also key: you want a uniform pressure difference across the radiator to achieve a uniform flow rate. 
* The angle of the radiator: You can angle it to about 30° (some even say 45°) relative to the airflow without any significant loss in cooling power. [citation needed] 
* single pass v double pass

=Radiator Types=
cross flow / downflow radiator, radiator form factors, and why we all use them
=Radiator Placement=
======Side======
======Rear======
======Multiple======
=System Design=
must be cooled w water only(IC and EV) or oil(EV). 
no additives 
Must be able to pass 45 deg tilt test w no leaks
===Hosing===
type and sizing
===Routing===
keep it short and straight
===Filling and Bleeding===
===Catch Can===
just crush a 1L beer and spray paint the can black, its what we all did, not gonna get any lighter or cheaper.
===Data and Data collection===
see [[:Category:Data Acquisition|Data Acquisition]]

=Other applications=
===Brake cooling===

* Convective
** ducting
** theyre spinning hot disks, they have natural convection
* Radiation

===Oil cooling===
Many engines have an OEM oil/water heat exchanger. From my experience with the 600rr, these are very compact and well integrated with the original powertrain system. Most teams use what is close to the manufacturer's recommended engine oil and the water coolant should be a perfectly fine substitute for the antifreeze solution on the OEM bikes.

why you would want to cool oil
* If it boils or denatures bad things happen - Novotny
* thanks, lol, just a placeholder, isnt meant to be a question, poor phrasing on my end - simon
* all good, I was confused :')

===Intercooler===
===Driver cooling===
lmao

[[Category: Internal Combustion]]

Scrutineering

2021-08-18T19:09:27Z

RealHumanBean:

Each competition will have a different scrutineering method, and each Vehicle Type (EV, CV and DV) will do so. It is absolutely essential to have multiple team members read the competition rules in their entirety and then work through the entire scrutineering checklist in advance of inspection at competition to avoid spending valuable time making modifications to the vehicle. Most teams will have to make very minor adjustments to firewall or similar areas but keeping those changes at scrutineering minimal is a critical goal.
=Scrutineering by Competition=
==FSAE==
==Formula Student Germany==
The FSG technical inspection is divided into the following parts<ref>FS Rules 2020 V1.0. (2019, September 13). Retrieved from https://www.formulastudent.de/fsg/rules/</ref>:
{| class="wikitable" style="width: 752px; border-color: #000000;" data-mce-style="width: 752px; border-color: #000000;"
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="height: 16px; width: 170px; text-align: center;" data-mce-style="height: 16px; width: 170px; text-align: center;"|'''CV'''
| style="height: 16px; width: 187px; text-align: center;" data-mce-style="height: 16px; width: 187px; text-align: center;"|'''EV'''
| style="height: 16px; width: 160px; text-align: center;" data-mce-style="height: 16px; width: 160px; text-align: center;"|'''DV'''
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="text-align: center; height: 16px; width: 517px;" colspan="3" data-mce-style="text-align: center; height: 16px; width: 517px;"|''' Pre-Inspection '''
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="height: 16px; width: 170px; text-align: center;" data-mce-style="height: 16px; width: 170px; text-align: center;"|###
| style="height: 16px; width: 187px; text-align: center;" data-mce-style="height: 16px; width: 187px; text-align: center;"|Accumulator Inspection
| style="height: 16px; width: 160px; text-align: center;" data-mce-style="height: 16px; width: 160px; text-align: center;"|###
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="height: 16px; width: 170px; text-align: center;" data-mce-style="height: 16px; width: 170px; text-align: center;"|###
| style="height: 16px; width: 187px; text-align: center;" data-mce-style="height: 16px; width: 187px; text-align: center;"|Electrical Inspection
| style="height: 16px; width: 160px; text-align: center;" data-mce-style="height: 16px; width: 160px; text-align: center;"|###
|- style="height: 5px;" data-mce-style="height: 5px;"
| style="height: 5px; width: 517px; text-align: center;" colspan="3" data-mce-style="height: 5px; width: 517px; text-align: center;"|'''Mechanical Inspection '''
|- style="height: 0.262497px;" data-mce-style="height: 0.262497px;"
| style="height: 0.262497px; width: 170px; text-align: center;" data-mce-style="height: 0.262497px; width: 170px; text-align: center;"|###
| style="height: 0.262497px; width: 187px; text-align: center;" data-mce-style="height: 0.262497px; width: 187px; text-align: center;"|###
| style="height: 0.262497px; width: 160px; text-align: center;" data-mce-style="height: 0.262497px; width: 160px; text-align: center;"|Driverless Inspection
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="height: 16px; text-align: center; width: 517px;" colspan="3" data-mce-style="height: 16px; text-align: center; width: 517px;"|''' Tilt Test '''
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="height: 16px; text-align: center; width: 517px;" colspan="3" data-mce-style="height: 16px; text-align: center; width: 517px;"|''' Vehicle Weighing '''
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="height: 16px; text-align: center; width: 170px;" data-mce-style="height: 16px; text-align: center; width: 170px;"|Noise Test
| style="height: 16px; text-align: center; width: 187px;" data-mce-style="height: 16px; text-align: center; width: 187px;"|Rain Test
| style="height: 16px; width: 160px; text-align: center;" data-mce-style="height: 16px; width: 160px; text-align: center;"|###
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="height: 16px; text-align: center; width: 517px;" colspan="3" data-mce-style="height: 16px; text-align: center; width: 517px;"|'''Brakes Test'''
|- style="height: 16px;" data-mce-style="height: 16px;"
| style="height: 16px; width: 170px; text-align: center;" data-mce-style="height: 16px; width: 170px; text-align: center;"|###
| style="height: 16px; width: 187px; text-align: center;" data-mce-style="height: 16px; width: 187px; text-align: center;"|###
| style="height: 16px; width: 160px; text-align: center;" data-mce-style="height: 16px; width: 160px; text-align: center;"|EBS Test
|}

=Scrutineering by Vehicle Class=
==Electric Vehicle==
===Preinspection===
===Accumulator Inspection===
====General====
Please only bring a finished and tested accumulator to a competition. How can you prove to others that it works if even you do not know yet?

Always wear safety goggles!

Always wear insulating gloves if even one of your maintenance plugs are connected!

Be familiar with your design, it will be obvious to the scrutineer, and possibly dangerous if you do not know your own accumulator.

Be prepared, read the inspection sheets, have your documents and datasheets ready.

You have a fixed time to finish, after that you are back in the queue.
====Charger assembly====
Must be a closed system

Have all your safety systems integrated and show them working.

All metal parts must be grounded to PE.
====Accumulator container====
Your SES must be approved! Please submit it in time, depending on the competition your scrutineering might be cut short here.

Put all necessary markings on your container! It has to be clear that it is an accumulator and who it belongs to.
===Tractive System===
===Low Voltage Sytem===
===Mechanical===
===Noise Test===
===Rain Test===
===Brake Test===
==Combustion Vehicle==
===Preinspection===
===Tractive System===
===Low Voltage Sytem===
===Mechanical===
===Noise Test===
===Rain Test===
===Brake Test===
==Driverless Vehicle==
===Preinspection===
===Tractive System===
===Low Voltage Sytem===
===Mechanical===
===Noise Test===
===Rain Test===
===Brake Test===
[[Category:Competition]]

Computational Fluid Dynamics

2021-08-18T00:36:29Z

RealHumanBean: /* Discretization */

'''Computational Fluid Dynamics (CFD)''' is the method by which fluid flow can be simulated using computational methods. It generally involves discretizing the Navier-Stokes equations (partial differential equations that govern fluid motion) into series of algebraic equations that can then be solved.

In a Formula SAE/Student context, CFD is predominantly used for two purposes; simulating an external aerodynamics package (including radiators and other cooling components) and simulating the intake and exhaust systems of internal combustion engines. While either problem have their unique challenges, the process of running CFD for their simulation it quite similar.

As with all computational simulations (CFD, structural simulation, track time simulators, etc.), they break down into series of steps which introduce their own sources of error (there will be error and you ''must'' account for it):

# Idealization
# Discretization
# Solution

Idealization are the physical assumptions made to come to some mathematical model. Discretization is the process of breaking up that mathematical model into a series of smaller, simpler problems. Solution is the process of actually solving those smaller problems. The errors associated with each step are modeling errors, discretization errors, and numerical errors, respectively (though the latter two are often grouped together). While this wiki page won't go into these steps in detail (it's worthy of a textbook), it's important to understand where errors come from and (thus) how to mitigate/fix them.

== Modeling (Idealization) ==

===Turbulence Modeling===
The extremely short answer for why turbulence modeling is necessary is that at the Reynold's numbers characteristic of FSAE aerodynamic systems, the large scale physics of the flow (skin friction, flow separation, and so on) depend on vortices and other fluid motions at exceptionally small length and time scales (this is Kolmogorov's limit). However, by the use of ensemble averaging (comparing the results of an indefinite number of near identical experiments such as 100 airfoils in 100 wind tunnels) or time averaging, the effects of these motions can be modeled using a reasonable mesh size and steady state modeling. Turbulence modeling is an exceptionally diverse and evolving field, but very generally Reynold's Averaged Navier Stokes (RANS) approaches which model the turbulence in the flow as transported and generated properties similar to mass and momentum are the most practical for engineering CFD. If I had a very large design space and I wanted to narrow it down to a few good designs, RANS would be the choice. Large Eddy Simulation (LES) uses RANS-like methods to model subgrid eddies and then more or less directly models the larger eddies in a truly 3D and transient simulation. LES is very expensive but can provide insights into the physics that RANS may not for certain problems. To dismiss LES for Formula Student out of hand would be foolish, but it is likely that the uncertainty in how the automotive geometry as constructed and how the vehicle is driven is larger than the gains made from the use of LES.

===Other Physical Assumptions===
External CFD for FSAE assumes incompressibility and constant gas properties; CFD for the powertrain system (whether in a conventional CFD tool like FLUENT or a dedicated tool like Ricardo WAVE) will not. CFD of course uses the continuum assumption and ignores chemical reactions unless you are doing something really crazy with the combustion modelling.

==Discretization==
Finite Volume is by far the most popular discretization method for fluid problems, though Finite Difference and Finite Element methods are equally applicable.

Beyond discretization method, geometric and fluid feature resolution are very important.

<math>y^+</math> is important near the wall. Essentially, it is a ratio of the mesh size near the wall to the estimated viscous sublayer thickness. What you want from this is highly dependent on the CFD model in use; if you want to resolve the boundary layer in detail, then it needs to be about 1. If you are using a RANS model and are less concerned about the boundary layer, then it can be higher. Check the documentation for the CFD solver to see what they recommend, and do a mesh refinement study, reporting out <math>y^+</math>and the parameters of interest at each mesh size. Results are more than useless without a mesh refinement study. With one, their slightly more useful.

== Solution ==

Description of order of accuracy considerations and convergence criteria

== Solvers ==

ANSYS, Star CCM, OpenFOAM, SimScale (which is just cloud based OpenFOAM).

==Fun Acronyms==

* Colorful Fluid Dynamics
* Can't Fit the Data.
* Conspiracy Fraud Deceit

[[Category:Body and Aero]]
[[Category:Internal Combustion]]
[[Category:Software]]

probably should have notes on meshing, model selection (suggested and why), analysis/postprocessing

Aerodynamic Basics

2021-08-18T00:31:12Z

RealHumanBean: /* Boundary Layers */

Aerodynamics in FSAE can be used to describe the interaction of air and the racecar, in particular its bodywork and aerodynamic elements such as wings, diffusers and fins. It can be analysed by the use of [[Computational Fluid Dynamics]]. The performance of aerodynamic elements can be described by parameters such as the coefficient of Lift (<math>C_l</math>), coefficient of Drag (<math>C_d</math>) and the ratio of <math>C_l/C_d</math>.
==Conceptual aspect of Aerodynamics==
Aerodynamics is not necessary to make a car go around a racetrack. Check beforehand if your car benefits from aerodynamic elements. Simple laptime simulation usually includes lift and drag coefficents and helps you determine your target goals.
==Key Parameters==

Coefficient of Lift, <math>C_l</math>

Coefficient of Drag, <math>C_d</math>

Lift to Drag ratio, <math>C_l/C_d</math>

==Boundary Layers==
There are many resources available about what exactly boundary layers are, why they exist, and other useful information. This will focus on FSAE applications, as they are fairly unique.

Beyond "what is a boundary layer" type questions, I ''highly'' recommend reading ''High Lift Aerodynamics''<ref>A. Smith, “High Lift Aerodynamics,” Journal of Aircraft, vol. 12, no. 6, pp. 501–539, 1975, doi:
[https://doi.org/10.2514/3.59830 10.2514/3.59830]</ref>, as it contains many of the fundamentals for the limitations of downforce generation. Most of what follows is a summary of the paper.

===Laminar, Turbulent, and Transition===

* Boundary layers (BL) can be either laminar, or turbulent
** Neither is "worse" or "better" than the other. They are simply different and have different effects aero systems.
* When a BL initially forms, it is laminar. Gradually fluctuations destabilize the flow and it becomes turbulent.
** This is known as '''(BL) transition'''
* The fluctuations may come naturally (from atmospheric turbulence or surface imperfections) or be induced artificially by "BL trips" or vortex generators
** The artificial methods force the transition to occur sooner than it would otherwise

* Determining when a boundary layer transitions is a function of it's Reynolds Number, <math>Re_x</math>, using <math>x</math> (distance along a wall) as its characteristic length scale. The boundary layer thickness can also be described non-dimensionally as <math>Re_\theta</math> where <math>\theta</math> is the local boundary layer thickness; this defines the boundary layer properties strictly in terms of local variables, as the meaning of "x" becomes less useful when the streamwise pressure gradient varies over the surface of the airfoil. 
** The higher the Reynolds number the more likely it is to be turbulent (over a certain level, it is more-or-less guaranteed)
** Therefore, increasing flow velocity decreases the distance at which BL transition occurs

===Pressure Gradients and Separation===

* Flow separation occurs as a direct result of the existence of boundary layers
** Hence why "flow separation" and "boundary layer separation" are synonymous
* Pressure gradients describe the force being applied to the fluid as it moves
** A pressure gradient that pushes ''with'' the (bulk) fluid motion is known as a '''Favorable Pressure Gradient (FPG)'''
** A pressure gradient that pushes ''against'' the (bulk) fluid motion is known as an '''Adverse Pressure Gradient (APG)'''
* APGs are what cause flow separation
** The APG pushes against the boundary layer such that the flow close to the wall (which is significantly slower than the flow outside the BL) begins to move backwards. At incipient separation, the shear stress at the wall reaches 0. 

===Low-<math>Re</math> effects===

* Laminar and Turbulent BL react to APGs differently:
** '''''Laminar BLs are more susceptible to separation than turbulent BLs'''''

* Airfoils feature an initial FPG, followed by an APG (also known as '''pressure recovery''')
* If the Reynolds number is high enough for an airfoil, BL transition occurs before the APG region
** This means that the "stronger" turbulent BL will resist the APG well
** If the Reynolds number is too low, the BL will not transition and a (weak) laminar BL will be forced to go through the APG region.
** '''''FSAE cars generally run in this Low-<math>Re</math> regime'''''

* Low-<math>Re</math> phenomenon include:
** "Premature" separation (compared to running the airfoil at higher <math>Re</math>)
** Hysteresis
*** The AoA at which separation occurs is different when increasing AoA than decreasing AoA
*** See the [https://m-selig.ae.illinois.edu/uiuc_lsat.html UIUC LSAT database] for plots demonstrating this effect (ie. compare the differences in polar plots between different <math>Re</math>)

* Unless your airfoil is operating outside the Low-<math>Re</math> regime (generally around <math>Re_c \approx 25,000</math>, though this is airfoil dependent), use airfoils explicitly designed for Low-<math>Re</math> regime
** These are meant to place the boundary layer transition point ahead of the APG region of the airfoil (or to "help" the BL transition sooner)
** S1223 airfoil is the quintessential airfoil design for this regime (at least for high lift applications, as would be found in FSAE cars)

'''Important Note for CFD:'''
* Low-<math>Re</math> effects are generally ''NOT'' well-captured by CFD, as many common turbulence models treat the BL as always turbulent. Modern commercial CFD codes do include transitional RANS models which are of some utility.
** There are special "transition" models, but they require empirical calibration to work correctly. 
** Even if you have the empirical calibration data, BL transitions is ''very'' sensitive to surface roughness, surface shape, atmospheric conditions, etc. FSAE manufacturing processes can be rather crude and a defect near the leading edge has a massive effect on the flow over the rest of the airfoil chord. 
** My advice is to simply trust wind tunnel data (such as [https://m-selig.ae.illinois.edu/uiuc_lsat.html UIUC LSAT]) to determine whether airfoils operating in Low-<math>Re</math>. If they are not, then the CFD assumptions aren't broken. If they are, then don't rely on CFD. CFD can arguably provide very good results pointing you towards a relatively optimal design even in the transitional regime, but not necessarily for providing a precise number for lift and drag coefficients. Like any other engineering tool, it has its purpose, but must be supplemented by sound engineering reasoning and experimental testing and validation. 

==Downforce==
[[Category:Body and Aero]]

Threaded Fasteners

2021-02-12T20:40:52Z

RealHumanBean: /* Torque Accuracy */

Threaded fasteners used in FS are most typically made of steel but are sometimes also made of stainless, titanium, or aluminum.
=Standards=
There are two main threaded fastener standards: metric and inch. Within these two categories lay additional standards set by various organisations. These standards may are often intercompatible but can differ in head size, strength, alloy, coating, pitch, and local avaliability. Teams that use both (e.g. a team in the U.S. with metric fasteners for the engine and inch fasteners for the rest of the car) should be extremely careful not to mix up the fasteners as certain metric/inch fasteners can thread with each other and compromise a bolted joint.
==Metric==
Metric screws are listed in the following way:<code><nowiki>M6x25 x 1mm Class 8.8</nowiki></code>. The M6 referes to the major diameter being 6mm, 25: the shaft length is 25mm, and the pitch is 1 thread per 1mm. A class 8.8 bolt is a medium strength steel bolt with a tensile strength of about 800MPa and about 80% of that being the yield strength.
===ISO===
Wikipedia [https://en.wikipedia.org/wiki/ISO_metric_screw_thread ISO Metric Screw Threads] has tables listing preferred sizes, and pitch.
==Inch==
Inch screws are listed in the following way:<code><nowiki>1/4-20 x 1 Grade 5</nowiki></code>. The 1/4 is the major diameter of 1/4in, a thread pitch of 20 threads per inch, and a length of 1in. A grade 5 bolt is a medium strength steel bolt with a tensile strength of about _ksi and a yield strength of _ksi.
===SAE===
[grades, charts, etc...]
===NAS===
NAS Shear bolts are often used in suspension systems because of their tight diameter tolerances, which means less compliance.

=Screw Types=

{| class="wikitable"
|-
|Photo
|Names
|Description
|-
|[[File:hexhead_mcmaster.png|50px]]
|Hex head
| 
|-
|[[File:12point_mcmaster.png|50px]]
|Twelve point
| 
|-
|[[File:sockethead_mcmaster.png|50px]]
|Socket head

Allen® head
| 
|-
|[[File:shoulder_mcmaster.png|50px]]
|Shoulder screw
| 
|-
|[[File:setscrew_mcmaster.png|50px]]
|Set screw
| 
|-
| 
|Quarter turn

[https://www.southco.com/en-us/product/hierarchy.html?hid=7345 DZUS® fastener]<ref>https://en.wikipedia.org/wiki/Dzus_fastener</ref>
|A specialty fastener that allows quick installation and removal of [[Body Panel|body panels]].
|}
===Reduced Loadability===
Countersunk, button head, and low profile bolts have weaker heads than hex head or socket head bolts, which can cause them to fail at the base of the head instead of the shank, and at lower load then the shank could withstand. The ISO/DIN standards state that the metric bolts will have "reduced loadability" of 80%, and will be labeled with a "0" before the class. ie. Class 08.8, 010.9, or 012.9.

* '''Countersunk head''': The title of table 3 from ISO 10642:1997(E) states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"
* '''Low Profile Socket Head''': The title of table 3 from DIN 7984 states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"
* '''Button Head''': The title of table 3 from ISO 7380: states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"

=====Caution:=====
There are many countersunk, button head, and low profile bolts produced that are
* '''not''' made according to one of the aforementioned standards. If they are not advertised as conforming to one of those standards, then their load capability cannot be confirmed (Or look up the standard they are made to).

* '''not''' made to a strength standard. These will not have 08.8, 010.9, or 012.9 etc printed on the head.

Also note that the Formula SAE / Formula Student rules may prevent countersunk, button head, or low profile bolts in certain locations.

=Nut Types=
===Hex Nut===
===Weld Nut / Riv-Nut===
==Locknut==
Locknuts resist loosening. Other methods can be used to resist loosening: [[Washer#Lock washer|lock washers]], [[Safety Wire|safety wire]], [[Locking Adhesive|locking adhesive]], or design. Most locknuts are only designed to be installed a few times otherwise their loosening resistance is diminished.

{| class="wikitable" style="width: 1661px;" data-mce-style="width: 1661px;"
|-
| style="width: 39px;" data-mce-style="width: 39px;"|Photo
| style="width: 106px;" data-mce-style="width: 106px;"|Common Name
| style="width: 1476px;" data-mce-style="width: 1476px;"|Description
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Jam nut
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Nylon nut
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Nylok
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Distorted nut

Stover nut

K-nut / Jet-nut
| style="width: 1476px;" data-mce-style="width: 1476px;"|Different components of the nut can be distorted to prevent loosening. For example: thread pitch and eccentricity. The temperature range is limited only by the parent metal or its plating and can be reused approximately 10 times before its locking capability is diminished<ref>Barrett, Richard. [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf|"Fastener Design Manual"], Nasa Reference Publication 1228 (1990) pp7</ref>. A K-nut or Jet-nut is ideal for high temperature applications.
|-
| style="width: 39px;" data-mce-style="width: 39px;"|
| style="width: 106px;" data-mce-style="width: 106px;"|Castle nut
| style="width: 1476px;" data-mce-style="width: 1476px;"|
|}

==Threaded Insert==
Threaded inserts are used to either repair a damaged set of threads or to make a more robust bolted joint. They are often referred to as "helical inserts" or "helicoils". A thread with a larger size than the bolt thread is tapped into the parent object. The helical insert is then screwed into the tapped hole and locked in place. The inside of the helical insert is the desired thread size. Threaded inserts are most useful for repairs or for parts where repeated assembly is foreseen. Aluminum parts are especially prone to being stripped when torqued, as a FSAE team will likely assemble and disassembled components such as engine casings far more frequently (and roughly!) than the manufacturers predict. Therefore, a set of helical inserts and associated tools are very useful for common fasteners like M6x1.0 screws for engines.

=Fastener Characteristics (how to choose)=

* Initial Tensioning
* Initial Tightening Force
** Brings bolt close to "proof load"
* Deformation of threads (pic)
* Maintenance schedule

=Torque=
Why torque a bolt? Create tension in the bolt which does the following:
* Prevent joint separation
* Reduces the cyclic stress that the bolt experiences during cyclic loading (at the cost of increases amplitude of the mean stress)
* Creates friction forces between the materials being clamped. The friction force can transmit shear forces, so the bolt itself isn't loaded in shear.

==Torque Accuracy==
The ultimate goal of torque is to tension the bolt. Unfortunately, torque is a very inaccurate method of achieving a specific tension. The tension can be off by +/- 25%.<ref name="NASA"></ref> It widely used because it is cheap to apply. When following a torque spec, be careful to follow the guidelines for assembling, as the use of lubricants such as engine oil can significantly change the measured torque for a given bolt stress (which is what you ultimately care about). NEVER try to guess torque by feel, no matter how experienced you are. A good torque wrench is essential, and torque wrenches that mechanically disengage when a dialed in torque is reached are nice to have.

==Calculate Torque==
The Fastenal Technical reference guide<ref name="Fastenal"> [http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FastenalTechnicalReferenceGuide.pdf Fastenal Technical Reference Guide]</ref> and the NASA Fastener Design Manual<ref name="NASA">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf NASA Fastener Design Manual</ref> (Pg 17 Alternative Torque Formula), and Shigley's<ref name="Shigleys">Budynas, Nisbett. Shigley's Mechanical Engineering Design 9th edition</ref> show the commonly used formula:

:<math>T=K*F*d</math>

Where
* <math> T </math> is Torque applied to the head of the fastener
* <math> K </math> is a Torque Coefficient related to friction. The Torque Coefficient depends on the materials, coatings, and lubricants (if present) of the connection. You can find a value from table VI of the Nasa manual,<ref name="NASA"></ref> or page 24 of the Fastenal Guide.<ref name="Fastenal"></ref>
* <math> F </math> is the preload tension force. Shigley's recommends <math>0.75 * F_{proof}</math> for non-permanent connections, where <math>F_{proof}</math> is the proof load of the bolt. Proof Stresses for common fasteners are listed in Shigley's, which can be used to calculate proof load. The tables in Shigley's show that proof stress is often 70%-80% of the yield strength of the bolt.<ref name="Shigleys"></ref>
* <math>d</math> is the diameter of the bolt.

=====Locknuts with Torque Calculations=====
Note that using nylon insert "locknuts" or prevailing torque nuts will increase the torque required for a given bolt tension. This torque is independent of the tension, so you can measure how much additional torque is required to overcome this locking feature, and simply add it on top of the calculation.

=====The Lazy Way=====

[https://www.fastenal.com/en/83/torque-calculator Fastenal Torque Calculator]

=Further Reading=
* [https://www.youtube.com/watch?v=f7qkHxG1v1E tarkka Fasteners Introduction Youtube Video]
* [https://www.fsaeonline.com/cdsweb/gen/DownloadDocument.aspx?DocumentID=5eafc7b3-b61d-470c-b929-7ad95d426d97 FSAE Online Series Resources: Threaded Fasteners for FSAE] If link breaks, it is found under fsaeonline.com > Series Resources > Design Event > Reference Documents.
* Machinerys Handbook
* [http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FastenalTechnicalReferenceGuide.pdf Fastenal Technical Reference Guide]
* [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf NASA Fastener Design Manual]
* Carroll Smith's ''Screw to Win''
* [https://www.mcmaster.com McMaster-Carr]
* Schaeffler Technical Pocket Guide (available in print or as an App)

=References=
<references /> 

[[category:Fasteners]]

Threaded Fasteners

2021-02-12T20:39:41Z

RealHumanBean: /* Standards */

Threaded fasteners used in FS are most typically made of steel but are sometimes also made of stainless, titanium, or aluminum.
=Standards=
There are two main threaded fastener standards: metric and inch. Within these two categories lay additional standards set by various organisations. These standards may are often intercompatible but can differ in head size, strength, alloy, coating, pitch, and local avaliability. Teams that use both (e.g. a team in the U.S. with metric fasteners for the engine and inch fasteners for the rest of the car) should be extremely careful not to mix up the fasteners as certain metric/inch fasteners can thread with each other and compromise a bolted joint.
==Metric==
Metric screws are listed in the following way:<code><nowiki>M6x25 x 1mm Class 8.8</nowiki></code>. The M6 referes to the major diameter being 6mm, 25: the shaft length is 25mm, and the pitch is 1 thread per 1mm. A class 8.8 bolt is a medium strength steel bolt with a tensile strength of about 800MPa and about 80% of that being the yield strength.
===ISO===
Wikipedia [https://en.wikipedia.org/wiki/ISO_metric_screw_thread ISO Metric Screw Threads] has tables listing preferred sizes, and pitch.
==Inch==
Inch screws are listed in the following way:<code><nowiki>1/4-20 x 1 Grade 5</nowiki></code>. The 1/4 is the major diameter of 1/4in, a thread pitch of 20 threads per inch, and a length of 1in. A grade 5 bolt is a medium strength steel bolt with a tensile strength of about _ksi and a yield strength of _ksi.
===SAE===
[grades, charts, etc...]
===NAS===
NAS Shear bolts are often used in suspension systems because of their tight diameter tolerances, which means less compliance.

=Screw Types=

{| class="wikitable"
|-
|Photo
|Names
|Description
|-
|[[File:hexhead_mcmaster.png|50px]]
|Hex head
| 
|-
|[[File:12point_mcmaster.png|50px]]
|Twelve point
| 
|-
|[[File:sockethead_mcmaster.png|50px]]
|Socket head

Allen® head
| 
|-
|[[File:shoulder_mcmaster.png|50px]]
|Shoulder screw
| 
|-
|[[File:setscrew_mcmaster.png|50px]]
|Set screw
| 
|-
| 
|Quarter turn

[https://www.southco.com/en-us/product/hierarchy.html?hid=7345 DZUS® fastener]<ref>https://en.wikipedia.org/wiki/Dzus_fastener</ref>
|A specialty fastener that allows quick installation and removal of [[Body Panel|body panels]].
|}
===Reduced Loadability===
Countersunk, button head, and low profile bolts have weaker heads than hex head or socket head bolts, which can cause them to fail at the base of the head instead of the shank, and at lower load then the shank could withstand. The ISO/DIN standards state that the metric bolts will have "reduced loadability" of 80%, and will be labeled with a "0" before the class. ie. Class 08.8, 010.9, or 012.9.

* '''Countersunk head''': The title of table 3 from ISO 10642:1997(E) states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"
* '''Low Profile Socket Head''': The title of table 3 from DIN 7984 states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"
* '''Button Head''': The title of table 3 from ISO 7380: states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"

=====Caution:=====
There are many countersunk, button head, and low profile bolts produced that are
* '''not''' made according to one of the aforementioned standards. If they are not advertised as conforming to one of those standards, then their load capability cannot be confirmed (Or look up the standard they are made to).

* '''not''' made to a strength standard. These will not have 08.8, 010.9, or 012.9 etc printed on the head.

Also note that the Formula SAE / Formula Student rules may prevent countersunk, button head, or low profile bolts in certain locations.

=Nut Types=
===Hex Nut===
===Weld Nut / Riv-Nut===
==Locknut==
Locknuts resist loosening. Other methods can be used to resist loosening: [[Washer#Lock washer|lock washers]], [[Safety Wire|safety wire]], [[Locking Adhesive|locking adhesive]], or design. Most locknuts are only designed to be installed a few times otherwise their loosening resistance is diminished.

{| class="wikitable" style="width: 1661px;" data-mce-style="width: 1661px;"
|-
| style="width: 39px;" data-mce-style="width: 39px;"|Photo
| style="width: 106px;" data-mce-style="width: 106px;"|Common Name
| style="width: 1476px;" data-mce-style="width: 1476px;"|Description
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Jam nut
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Nylon nut
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Nylok
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Distorted nut

Stover nut

K-nut / Jet-nut
| style="width: 1476px;" data-mce-style="width: 1476px;"|Different components of the nut can be distorted to prevent loosening. For example: thread pitch and eccentricity. The temperature range is limited only by the parent metal or its plating and can be reused approximately 10 times before its locking capability is diminished<ref>Barrett, Richard. [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf|"Fastener Design Manual"], Nasa Reference Publication 1228 (1990) pp7</ref>. A K-nut or Jet-nut is ideal for high temperature applications.
|-
| style="width: 39px;" data-mce-style="width: 39px;"|
| style="width: 106px;" data-mce-style="width: 106px;"|Castle nut
| style="width: 1476px;" data-mce-style="width: 1476px;"|
|}

==Threaded Insert==
Threaded inserts are used to either repair a damaged set of threads or to make a more robust bolted joint. They are often referred to as "helical inserts" or "helicoils". A thread with a larger size than the bolt thread is tapped into the parent object. The helical insert is then screwed into the tapped hole and locked in place. The inside of the helical insert is the desired thread size. Threaded inserts are most useful for repairs or for parts where repeated assembly is foreseen. Aluminum parts are especially prone to being stripped when torqued, as a FSAE team will likely assemble and disassembled components such as engine casings far more frequently (and roughly!) than the manufacturers predict. Therefore, a set of helical inserts and associated tools are very useful for common fasteners like M6x1.0 screws for engines.

=Fastener Characteristics (how to choose)=

* Initial Tensioning
* Initial Tightening Force
** Brings bolt close to "proof load"
* Deformation of threads (pic)
* Maintenance schedule

=Torque=
Why torque a bolt? Create tension in the bolt which does the following:
* Prevent joint separation
* Reduces the cyclic stress that the bolt experiences during cyclic loading (at the cost of increases amplitude of the mean stress)
* Creates friction forces between the materials being clamped. The friction force can transmit shear forces, so the bolt itself isn't loaded in shear.

==Torque Accuracy==
The ultimate goal of torque is to tension the bolt. Unfortunately, torque is a very inaccurate method of achieving a specific tension. The tension can be off by +/- 25%.<ref name="NASA"></ref> It widely used because it is cheap to apply. When following a torque spec, be careful to follow the guidelines for assembling, as the use of lubricants such as engine oil can significantly change the measured torque for a given bolt stress (which is what you ultimately care about). NEVER try to guess torque by feel, no matter how experienced you are. A good torque wrench is essential, and torque wrenches that mechanically disengaging when a dialed in torque is reached are nice to have.

==Calculate Torque==
The Fastenal Technical reference guide<ref name="Fastenal"> [http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FastenalTechnicalReferenceGuide.pdf Fastenal Technical Reference Guide]</ref> and the NASA Fastener Design Manual<ref name="NASA">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf NASA Fastener Design Manual</ref> (Pg 17 Alternative Torque Formula), and Shigley's<ref name="Shigleys">Budynas, Nisbett. Shigley's Mechanical Engineering Design 9th edition</ref> show the commonly used formula:

:<math>T=K*F*d</math>

Where
* <math> T </math> is Torque applied to the head of the fastener
* <math> K </math> is a Torque Coefficient related to friction. The Torque Coefficient depends on the materials, coatings, and lubricants (if present) of the connection. You can find a value from table VI of the Nasa manual,<ref name="NASA"></ref> or page 24 of the Fastenal Guide.<ref name="Fastenal"></ref>
* <math> F </math> is the preload tension force. Shigley's recommends <math>0.75 * F_{proof}</math> for non-permanent connections, where <math>F_{proof}</math> is the proof load of the bolt. Proof Stresses for common fasteners are listed in Shigley's, which can be used to calculate proof load. The tables in Shigley's show that proof stress is often 70%-80% of the yield strength of the bolt.<ref name="Shigleys"></ref>
* <math>d</math> is the diameter of the bolt.

=====Locknuts with Torque Calculations=====
Note that using nylon insert "locknuts" or prevailing torque nuts will increase the torque required for a given bolt tension. This torque is independent of the tension, so you can measure how much additional torque is required to overcome this locking feature, and simply add it on top of the calculation.

=====The Lazy Way=====

[https://www.fastenal.com/en/83/torque-calculator Fastenal Torque Calculator]

=Further Reading=
* [https://www.youtube.com/watch?v=f7qkHxG1v1E tarkka Fasteners Introduction Youtube Video]
* [https://www.fsaeonline.com/cdsweb/gen/DownloadDocument.aspx?DocumentID=5eafc7b3-b61d-470c-b929-7ad95d426d97 FSAE Online Series Resources: Threaded Fasteners for FSAE] If link breaks, it is found under fsaeonline.com > Series Resources > Design Event > Reference Documents.
* Machinerys Handbook
* [http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FastenalTechnicalReferenceGuide.pdf Fastenal Technical Reference Guide]
* [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf NASA Fastener Design Manual]
* Carroll Smith's ''Screw to Win''
* [https://www.mcmaster.com McMaster-Carr]
* Schaeffler Technical Pocket Guide (available in print or as an App)

=References=
<references /> 

[[category:Fasteners]]

Threaded Fasteners

2021-02-12T20:36:53Z

RealHumanBean: /* Torque Accuracy */

Threaded fasteners used in FS are most typically made of steel but are sometimes also made of stainless, titanium, or aluminum.
=Standards=
There are two main threaded fastener standards: metric and inch. Within these two categories lay additional standards set by various organisations. These standards may are often intercompatible but can differ in head size, strength, alloy, coating, pitch, and local avaliability.
==Metric==
Metric screws are listed in the following way:<code><nowiki>M6x25 x 1mm Class 8.8</nowiki></code>. The M6 referes to the major diameter being 6mm, 25: the shaft length is 25mm, and the pitch is 1 thread per 1mm. A class 8.8 bolt is a medium strength steel bolt with a tensile strength of about 800MPa and about 80% of that being the yield strength.
===ISO===
Wikipedia [https://en.wikipedia.org/wiki/ISO_metric_screw_thread ISO Metric Screw Threads] has tables listing preferred sizes, and pitch.
==Inch==
Inch screws are listed in the following way:<code><nowiki>1/4-20 x 1 Grade 5</nowiki></code>. The 1/4 is the major diameter of 1/4in, a thread pitch of 20 threads per inch, and a length of 1in. A grade 5 bolt is a medium strength steel bolt with a tensile strength of about _ksi and a yield strength of _ksi.
===SAE===
[grades, charts, etc...]
===NAS===
NAS Shear bolts are often used in suspension systems because of their tight diameter tolerances, which means less compliance.
=Screw Types=

{| class="wikitable"
|-
|Photo
|Names
|Description
|-
|[[File:hexhead_mcmaster.png|50px]]
|Hex head
| 
|-
|[[File:12point_mcmaster.png|50px]]
|Twelve point
| 
|-
|[[File:sockethead_mcmaster.png|50px]]
|Socket head

Allen® head
| 
|-
|[[File:shoulder_mcmaster.png|50px]]
|Shoulder screw
| 
|-
|[[File:setscrew_mcmaster.png|50px]]
|Set screw
| 
|-
| 
|Quarter turn

[https://www.southco.com/en-us/product/hierarchy.html?hid=7345 DZUS® fastener]<ref>https://en.wikipedia.org/wiki/Dzus_fastener</ref>
|A specialty fastener that allows quick installation and removal of [[Body Panel|body panels]].
|}
===Reduced Loadability===
Countersunk, button head, and low profile bolts have weaker heads than hex head or socket head bolts, which can cause them to fail at the base of the head instead of the shank, and at lower load then the shank could withstand. The ISO/DIN standards state that the metric bolts will have "reduced loadability" of 80%, and will be labeled with a "0" before the class. ie. Class 08.8, 010.9, or 012.9.

* '''Countersunk head''': The title of table 3 from ISO 10642:1997(E) states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"
* '''Low Profile Socket Head''': The title of table 3 from DIN 7984 states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"
* '''Button Head''': The title of table 3 from ISO 7380: states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"

=====Caution:=====
There are many countersunk, button head, and low profile bolts produced that are
* '''not''' made according to one of the aforementioned standards. If they are not advertised as conforming to one of those standards, then their load capability cannot be confirmed (Or look up the standard they are made to).

* '''not''' made to a strength standard. These will not have 08.8, 010.9, or 012.9 etc printed on the head.

Also note that the Formula SAE / Formula Student rules may prevent countersunk, button head, or low profile bolts in certain locations.

=Nut Types=
===Hex Nut===
===Weld Nut / Riv-Nut===
==Locknut==
Locknuts resist loosening. Other methods can be used to resist loosening: [[Washer#Lock washer|lock washers]], [[Safety Wire|safety wire]], [[Locking Adhesive|locking adhesive]], or design. Most locknuts are only designed to be installed a few times otherwise their loosening resistance is diminished.

{| class="wikitable" style="width: 1661px;" data-mce-style="width: 1661px;"
|-
| style="width: 39px;" data-mce-style="width: 39px;"|Photo
| style="width: 106px;" data-mce-style="width: 106px;"|Common Name
| style="width: 1476px;" data-mce-style="width: 1476px;"|Description
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Jam nut
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Nylon nut
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Nylok
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Distorted nut

Stover nut

K-nut / Jet-nut
| style="width: 1476px;" data-mce-style="width: 1476px;"|Different components of the nut can be distorted to prevent loosening. For example: thread pitch and eccentricity. The temperature range is limited only by the parent metal or its plating and can be reused approximately 10 times before its locking capability is diminished<ref>Barrett, Richard. [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf|"Fastener Design Manual"], Nasa Reference Publication 1228 (1990) pp7</ref>. A K-nut or Jet-nut is ideal for high temperature applications.
|-
| style="width: 39px;" data-mce-style="width: 39px;"|
| style="width: 106px;" data-mce-style="width: 106px;"|Castle nut
| style="width: 1476px;" data-mce-style="width: 1476px;"|
|}

==Threaded Insert==
Threaded inserts are used to either repair a damaged set of threads or to make a more robust bolted joint. They are often referred to as "helical inserts" or "helicoils". A thread with a larger size than the bolt thread is tapped into the parent object. The helical insert is then screwed into the tapped hole and locked in place. The inside of the helical insert is the desired thread size. Threaded inserts are most useful for repairs or for parts where repeated assembly is foreseen. Aluminum parts are especially prone to being stripped when torqued, as a FSAE team will likely assemble and disassembled components such as engine casings far more frequently (and roughly!) than the manufacturers predict. Therefore, a set of helical inserts and associated tools are very useful for common fasteners like M6x1.0 screws for engines.

=Fastener Characteristics (how to choose)=

* Initial Tensioning
* Initial Tightening Force
** Brings bolt close to "proof load"
* Deformation of threads (pic)
* Maintenance schedule

=Torque=
Why torque a bolt? Create tension in the bolt which does the following:
* Prevent joint separation
* Reduces the cyclic stress that the bolt experiences during cyclic loading (at the cost of increases amplitude of the mean stress)
* Creates friction forces between the materials being clamped. The friction force can transmit shear forces, so the bolt itself isn't loaded in shear.

==Torque Accuracy==
The ultimate goal of torque is to tension the bolt. Unfortunately, torque is a very inaccurate method of achieving a specific tension. The tension can be off by +/- 25%.<ref name="NASA"></ref> It widely used because it is cheap to apply. When following a torque spec, be careful to follow the guidelines for assembling, as the use of lubricants such as engine oil can significantly change the measured torque for a given bolt stress (which is what you ultimately care about). NEVER try to guess torque by feel, no matter how experienced you are. A good torque wrench is essential, and torque wrenches that mechanically disengaging when a dialed in torque is reached are nice to have.

==Calculate Torque==
The Fastenal Technical reference guide<ref name="Fastenal"> [http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FastenalTechnicalReferenceGuide.pdf Fastenal Technical Reference Guide]</ref> and the NASA Fastener Design Manual<ref name="NASA">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf NASA Fastener Design Manual</ref> (Pg 17 Alternative Torque Formula), and Shigley's<ref name="Shigleys">Budynas, Nisbett. Shigley's Mechanical Engineering Design 9th edition</ref> show the commonly used formula:

:<math>T=K*F*d</math>

Where
* <math> T </math> is Torque applied to the head of the fastener
* <math> K </math> is a Torque Coefficient related to friction. The Torque Coefficient depends on the materials, coatings, and lubricants (if present) of the connection. You can find a value from table VI of the Nasa manual,<ref name="NASA"></ref> or page 24 of the Fastenal Guide.<ref name="Fastenal"></ref>
* <math> F </math> is the preload tension force. Shigley's recommends <math>0.75 * F_{proof}</math> for non-permanent connections, where <math>F_{proof}</math> is the proof load of the bolt. Proof Stresses for common fasteners are listed in Shigley's, which can be used to calculate proof load. The tables in Shigley's show that proof stress is often 70%-80% of the yield strength of the bolt.<ref name="Shigleys"></ref>
* <math>d</math> is the diameter of the bolt.

=====Locknuts with Torque Calculations=====
Note that using nylon insert "locknuts" or prevailing torque nuts will increase the torque required for a given bolt tension. This torque is independent of the tension, so you can measure how much additional torque is required to overcome this locking feature, and simply add it on top of the calculation.

=====The Lazy Way=====

[https://www.fastenal.com/en/83/torque-calculator Fastenal Torque Calculator]

=Further Reading=
* [https://www.youtube.com/watch?v=f7qkHxG1v1E tarkka Fasteners Introduction Youtube Video]
* [https://www.fsaeonline.com/cdsweb/gen/DownloadDocument.aspx?DocumentID=5eafc7b3-b61d-470c-b929-7ad95d426d97 FSAE Online Series Resources: Threaded Fasteners for FSAE] If link breaks, it is found under fsaeonline.com > Series Resources > Design Event > Reference Documents.
* Machinerys Handbook
* [http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FastenalTechnicalReferenceGuide.pdf Fastenal Technical Reference Guide]
* [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf NASA Fastener Design Manual]
* Carroll Smith's ''Screw to Win''
* [https://www.mcmaster.com McMaster-Carr]
* Schaeffler Technical Pocket Guide (available in print or as an App)

=References=
<references /> 

[[category:Fasteners]]

Threaded Fasteners

2021-02-12T20:33:47Z

RealHumanBean: /* Threaded Insert */

Threaded fasteners used in FS are most typically made of steel but are sometimes also made of stainless, titanium, or aluminum.
=Standards=
There are two main threaded fastener standards: metric and inch. Within these two categories lay additional standards set by various organisations. These standards may are often intercompatible but can differ in head size, strength, alloy, coating, pitch, and local avaliability.
==Metric==
Metric screws are listed in the following way:<code><nowiki>M6x25 x 1mm Class 8.8</nowiki></code>. The M6 referes to the major diameter being 6mm, 25: the shaft length is 25mm, and the pitch is 1 thread per 1mm. A class 8.8 bolt is a medium strength steel bolt with a tensile strength of about 800MPa and about 80% of that being the yield strength.
===ISO===
Wikipedia [https://en.wikipedia.org/wiki/ISO_metric_screw_thread ISO Metric Screw Threads] has tables listing preferred sizes, and pitch.
==Inch==
Inch screws are listed in the following way:<code><nowiki>1/4-20 x 1 Grade 5</nowiki></code>. The 1/4 is the major diameter of 1/4in, a thread pitch of 20 threads per inch, and a length of 1in. A grade 5 bolt is a medium strength steel bolt with a tensile strength of about _ksi and a yield strength of _ksi.
===SAE===
[grades, charts, etc...]
===NAS===
NAS Shear bolts are often used in suspension systems because of their tight diameter tolerances, which means less compliance.
=Screw Types=

{| class="wikitable"
|-
|Photo
|Names
|Description
|-
|[[File:hexhead_mcmaster.png|50px]]
|Hex head
| 
|-
|[[File:12point_mcmaster.png|50px]]
|Twelve point
| 
|-
|[[File:sockethead_mcmaster.png|50px]]
|Socket head

Allen® head
| 
|-
|[[File:shoulder_mcmaster.png|50px]]
|Shoulder screw
| 
|-
|[[File:setscrew_mcmaster.png|50px]]
|Set screw
| 
|-
| 
|Quarter turn

[https://www.southco.com/en-us/product/hierarchy.html?hid=7345 DZUS® fastener]<ref>https://en.wikipedia.org/wiki/Dzus_fastener</ref>
|A specialty fastener that allows quick installation and removal of [[Body Panel|body panels]].
|}
===Reduced Loadability===
Countersunk, button head, and low profile bolts have weaker heads than hex head or socket head bolts, which can cause them to fail at the base of the head instead of the shank, and at lower load then the shank could withstand. The ISO/DIN standards state that the metric bolts will have "reduced loadability" of 80%, and will be labeled with a "0" before the class. ie. Class 08.8, 010.9, or 012.9.

* '''Countersunk head''': The title of table 3 from ISO 10642:1997(E) states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"
* '''Low Profile Socket Head''': The title of table 3 from DIN 7984 states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"
* '''Button Head''': The title of table 3 from ISO 7380: states "Minimum ultimate tensile loads (...) 80% of the values specified in ISO 898-1"

=====Caution:=====
There are many countersunk, button head, and low profile bolts produced that are
* '''not''' made according to one of the aforementioned standards. If they are not advertised as conforming to one of those standards, then their load capability cannot be confirmed (Or look up the standard they are made to).

* '''not''' made to a strength standard. These will not have 08.8, 010.9, or 012.9 etc printed on the head.

Also note that the Formula SAE / Formula Student rules may prevent countersunk, button head, or low profile bolts in certain locations.

=Nut Types=
===Hex Nut===
===Weld Nut / Riv-Nut===
==Locknut==
Locknuts resist loosening. Other methods can be used to resist loosening: [[Washer#Lock washer|lock washers]], [[Safety Wire|safety wire]], [[Locking Adhesive|locking adhesive]], or design. Most locknuts are only designed to be installed a few times otherwise their loosening resistance is diminished.

{| class="wikitable" style="width: 1661px;" data-mce-style="width: 1661px;"
|-
| style="width: 39px;" data-mce-style="width: 39px;"|Photo
| style="width: 106px;" data-mce-style="width: 106px;"|Common Name
| style="width: 1476px;" data-mce-style="width: 1476px;"|Description
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Jam nut
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Nylon nut
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Nylok
| style="width: 1476px;" data-mce-style="width: 1476px;"| 
|-
| style="width: 39px;" data-mce-style="width: 39px;"| 
| style="width: 106px;" data-mce-style="width: 106px;"|Distorted nut

Stover nut

K-nut / Jet-nut
| style="width: 1476px;" data-mce-style="width: 1476px;"|Different components of the nut can be distorted to prevent loosening. For example: thread pitch and eccentricity. The temperature range is limited only by the parent metal or its plating and can be reused approximately 10 times before its locking capability is diminished<ref>Barrett, Richard. [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf|"Fastener Design Manual"], Nasa Reference Publication 1228 (1990) pp7</ref>. A K-nut or Jet-nut is ideal for high temperature applications.
|-
| style="width: 39px;" data-mce-style="width: 39px;"|
| style="width: 106px;" data-mce-style="width: 106px;"|Castle nut
| style="width: 1476px;" data-mce-style="width: 1476px;"|
|}

==Threaded Insert==
Threaded inserts are used to either repair a damaged set of threads or to make a more robust bolted joint. They are often referred to as "helical inserts" or "helicoils". A thread with a larger size than the bolt thread is tapped into the parent object. The helical insert is then screwed into the tapped hole and locked in place. The inside of the helical insert is the desired thread size. Threaded inserts are most useful for repairs or for parts where repeated assembly is foreseen. Aluminum parts are especially prone to being stripped when torqued, as a FSAE team will likely assemble and disassembled components such as engine casings far more frequently (and roughly!) than the manufacturers predict. Therefore, a set of helical inserts and associated tools are very useful for common fasteners like M6x1.0 screws for engines.

=Fastener Characteristics (how to choose)=

* Initial Tensioning
* Initial Tightening Force
** Brings bolt close to "proof load"
* Deformation of threads (pic)
* Maintenance schedule

=Torque=
Why torque a bolt? Create tension in the bolt which does the following:
* Prevent joint separation
* Reduces the cyclic stress that the bolt experiences during cyclic loading (at the cost of increases amplitude of the mean stress)
* Creates friction forces between the materials being clamped. The friction force can transmit shear forces, so the bolt itself isn't loaded in shear.

==Torque Accuracy==
The ultimate goal of torque is to tension the bolt. Unfortunately, torque is a very inaccurate method of achieving a specific tension. The tension can be off by +/- 25%.<ref name="NASA"></ref> It widely used because it is cheap to apply.

==Calculate Torque==
The Fastenal Technical reference guide<ref name="Fastenal"> [http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FastenalTechnicalReferenceGuide.pdf Fastenal Technical Reference Guide]</ref> and the NASA Fastener Design Manual<ref name="NASA">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf NASA Fastener Design Manual</ref> (Pg 17 Alternative Torque Formula), and Shigley's<ref name="Shigleys">Budynas, Nisbett. Shigley's Mechanical Engineering Design 9th edition</ref> show the commonly used formula:

:<math>T=K*F*d</math>

Where
* <math> T </math> is Torque applied to the head of the fastener
* <math> K </math> is a Torque Coefficient related to friction. The Torque Coefficient depends on the materials, coatings, and lubricants (if present) of the connection. You can find a value from table VI of the Nasa manual,<ref name="NASA"></ref> or page 24 of the Fastenal Guide.<ref name="Fastenal"></ref>
* <math> F </math> is the preload tension force. Shigley's recommends <math>0.75 * F_{proof}</math> for non-permanent connections, where <math>F_{proof}</math> is the proof load of the bolt. Proof Stresses for common fasteners are listed in Shigley's, which can be used to calculate proof load. The tables in Shigley's show that proof stress is often 70%-80% of the yield strength of the bolt.<ref name="Shigleys"></ref>
* <math>d</math> is the diameter of the bolt.

=====Locknuts with Torque Calculations=====
Note that using nylon insert "locknuts" or prevailing torque nuts will increase the torque required for a given bolt tension. This torque is independent of the tension, so you can measure how much additional torque is required to overcome this locking feature, and simply add it on top of the calculation.

=====The Lazy Way=====

[https://www.fastenal.com/en/83/torque-calculator Fastenal Torque Calculator]

=Further Reading=
* [https://www.youtube.com/watch?v=f7qkHxG1v1E tarkka Fasteners Introduction Youtube Video]
* [https://www.fsaeonline.com/cdsweb/gen/DownloadDocument.aspx?DocumentID=5eafc7b3-b61d-470c-b929-7ad95d426d97 FSAE Online Series Resources: Threaded Fasteners for FSAE] If link breaks, it is found under fsaeonline.com > Series Resources > Design Event > Reference Documents.
* Machinerys Handbook
* [http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FastenalTechnicalReferenceGuide.pdf Fastenal Technical Reference Guide]
* [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf NASA Fastener Design Manual]
* Carroll Smith's ''Screw to Win''
* [https://www.mcmaster.com McMaster-Carr]
* Schaeffler Technical Pocket Guide (available in print or as an App)

=References=
<references /> 

[[category:Fasteners]]

Computational Fluid Dynamics

2020-08-25T04:15:10Z

RealHumanBean: /* Other Physical Assumptions */

'''Computational Fluid Dynamics (CFD)''' is the method by which fluid flow can be simulated using computational methods. It generally involves discretizing the Navier-Stokes equations (partial differential equations that govern fluid motion) into series of algebraic equations that can then be solved.

In a Formula SAE/Student context, CFD is predominantly used for two purposes; simulating an external aerodynamics package (including radiators and other cooling components) and simulating the intake and exhaust systems of internal combustion engines. While either problem have their unique challenges, the process of running CFD for their simulation it quite similar.

As with all computational simulations (CFD, structural simulation, track time simulators, etc.), they break down into series of steps which introduce their own sources of error (there will be error and you ''must'' account for it):

# Idealization
# Discretization
# Solution

Idealization are the physical assumptions made to come to some mathematical model. Discretization is the process of breaking up that mathematical model into a series of smaller, simpler problems. Solution is the process of actually solving those smaller problems. The errors associated with each step are modeling errors, discretization errors, and numerical errors, respectively (though the latter two are often grouped together). While this wiki page won't go into these steps in detail (it's worthy of a textbook), it's important to understand where errors come from and (thus) how to mitigate/fix them.

== Modeling (Idealization) ==

===Turbulence Modeling===
The extremely short answer for why turbulence modeling is necessary is that at the Reynold's numbers characteristic of FSAE aerodynamic systems, the large scale physics of the flow (skin friction, flow separation, and so on) depend on vortices and other fluid motions at exceptionally small length and time scales (this is Kolmogorov's limit). However, by the use of ensemble averaging (comparing the results of an indefinite number of near identical experiments such as 100 airfoils in 100 wind tunnels) or time averaging, the effects of these motions can be modeled using a reasonable mesh size and steady state modeling. Turbulence modeling is an exceptionally diverse and evolving field, but very generally Reynold's Averaged Navier Stokes (RANS) approaches which model the turbulence in the flow as transported and generated properties similar to mass and momentum are the most practical for engineering CFD. If I had a very large design space and I wanted to narrow it down to a few good designs, RANS would be the choice. Large Eddy Simulation (LES) uses RANS-like methods to model subgrid eddies and then more or less directly models the larger eddies in a truly 3D and transient simulation. LES is very expensive but can provide insights into the physics that RANS may not for certain problems. To dismiss LES for Formula Student out of hand would be foolish, but it is likely that the uncertainty in how the automotive geometry as constructed and how the vehicle is driven is larger than the gains made from the use of LES.

===Other Physical Assumptions===
External CFD for FSAE assumes incompressibility and constant gas properties; CFD for the powertrain system (whether in a conventional CFD tool like FLUENT or a dedicated tool like Ricardo WAVE) will not. CFD of course uses the continuum assumption and ignores chemical reactions unless you are doing something really crazy with the combustion modelling.

== Discretization ==

Finite Volume is by far the most popular discretization method for fluid problems, though Finite Difference and Finite Element methods are equally applicable.

Beyond discretization method, geometric and fluid feature resolution are very important.

<math>y^+</math> is important near the wall

Results are more than useless without a mesh refinement study. With one, their slightly more useful.

== Solution ==

Description of order of accuracy considerations and convergence criteria

== Solvers ==

ANSYS, Star CCM, OpenFOAM, SimScale (which is just cloud based OpenFOAM).

==Fun Acronyms==

* Colorful Fluid Dynamics
* Can't Fit the Data.
* Conspiracy Fraud Deceit

[[Category:Body and Aero]]
[[Category:Internal Combustion]]
[[Category:Software]]

probably should have notes on meshing, model selection (suggested and why), analysis/postprocessing

Computational Fluid Dynamics

2020-08-25T04:12:25Z

RealHumanBean: /* Turbulence Modeling */

'''Computational Fluid Dynamics (CFD)''' is the method by which fluid flow can be simulated using computational methods. It generally involves discretizing the Navier-Stokes equations (partial differential equations that govern fluid motion) into series of algebraic equations that can then be solved.

In a Formula SAE/Student context, CFD is predominantly used for two purposes; simulating an external aerodynamics package (including radiators and other cooling components) and simulating the intake and exhaust systems of internal combustion engines. While either problem have their unique challenges, the process of running CFD for their simulation it quite similar.

As with all computational simulations (CFD, structural simulation, track time simulators, etc.), they break down into series of steps which introduce their own sources of error (there will be error and you ''must'' account for it):

# Idealization
# Discretization
# Solution

Idealization are the physical assumptions made to come to some mathematical model. Discretization is the process of breaking up that mathematical model into a series of smaller, simpler problems. Solution is the process of actually solving those smaller problems. The errors associated with each step are modeling errors, discretization errors, and numerical errors, respectively (though the latter two are often grouped together). While this wiki page won't go into these steps in detail (it's worthy of a textbook), it's important to understand where errors come from and (thus) how to mitigate/fix them.

== Modeling (Idealization) ==

===Turbulence Modeling===
The extremely short answer for why turbulence modeling is necessary is that at the Reynold's numbers characteristic of FSAE aerodynamic systems, the large scale physics of the flow (skin friction, flow separation, and so on) depend on vortices and other fluid motions at exceptionally small length and time scales (this is Kolmogorov's limit). However, by the use of ensemble averaging (comparing the results of an indefinite number of near identical experiments such as 100 airfoils in 100 wind tunnels) or time averaging, the effects of these motions can be modeled using a reasonable mesh size and steady state modeling. Turbulence modeling is an exceptionally diverse and evolving field, but very generally Reynold's Averaged Navier Stokes (RANS) approaches which model the turbulence in the flow as transported and generated properties similar to mass and momentum are the most practical for engineering CFD. If I had a very large design space and I wanted to narrow it down to a few good designs, RANS would be the choice. Large Eddy Simulation (LES) uses RANS-like methods to model subgrid eddies and then more or less directly models the larger eddies in a truly 3D and transient simulation. LES is very expensive but can provide insights into the physics that RANS may not for certain problems. To dismiss LES for Formula Student out of hand would be foolish, but it is likely that the uncertainty in how the automotive geometry as constructed and how the vehicle is driven is larger than the gains made from the use of LES.

=== Other Physical Assumptions ===

== Discretization ==

Finite Volume is by far the most popular discretization method for fluid problems, though Finite Difference and Finite Element methods are equally applicable.

Beyond discretization method, geometric and fluid feature resolution are very important.

<math>y^+</math> is important near the wall

Results are more than useless without a mesh refinement study. With one, their slightly more useful.

== Solution ==

Description of order of accuracy considerations and convergence criteria

== Solvers ==

ANSYS, Star CCM, OpenFOAM, SimScale (which is just cloud based OpenFOAM).

==Fun Acronyms==

* Colorful Fluid Dynamics
* Can't Fit the Data.
* Conspiracy Fraud Deceit

[[Category:Body and Aero]]
[[Category:Internal Combustion]]
[[Category:Software]]

probably should have notes on meshing, model selection (suggested and why), analysis/postprocessing

Aluminum

2020-06-24T18:21:38Z

RealHumanBean: /* 7075-T6 */

A metal which is commonly used for its light weight property while still being somewhat strong.

How to read the aluminum material names.

1xxx Aluminum, 99% minimum

2xxx Copper

3xxx Manganese

4xxx Silicon

5xxx Magnesium

6xxx Magnesium and Silicon

7xxx Zinc

8xxx Other Element

9xxx Unused

Fatigue Analogy: Aluminum runs short sprints while steel does marathons/
=1000 Series=
The 1000 series has "excellent corrosion resistance, high thermal and electrical conductivity, low mechanical properties, and excellent workability."
==1100==
Used in soft solid rivets

=2000 Series=
The 2000 series is generally heat-treated for optimum properties, and heat-treated properties can exceed mild steel. Notable alloys are 2024, the most widely used alloy in aircraft, and 2117, which is used in solid rivets.
==2024==
=3000 Series=
The 3000 series is best for non-structural uses. 3003 is a notable alloy for being easy to weld.
==3003==
3003 is 20% stronger than the 1000 series but is about as workable as pure aluminum. It can be TIG or gas welded, and is non-heat treatable. 3003-H14 is malleable and weldable. (<a href="https://www.oldcarsweekly.com/restoration/metalworking-101-fundamentals-of-fabrication">https://www.oldcarsweekly.com/restoration/metalworking-101-fundamentals-of-fabrication</a>)

=5000 Series=
5000 series alloys are used for tanks and fluid lines, and are moderate- to high-strength nonheat-treatable.
==5xxx==
=6000 Series=
The 6000 series has medium strength and good formability and corrosion resistance. A notable alloy is 6061.
==6061-T6==
High strength but somewhat brittle, hard to weld and may create stress cracks at the weld.

=7000 Series=
The 7000 series can be high-strength, with a notable alloy being 7075.
==7075-T6==
[[Category:Materials]]7075 is one of the strongest aluminum alloys and is frequently used in aerospace and automotive applications where both strength and weight are critical. The largest downside is that welding 7075 is not weldable.

Tensioner

2020-06-13T05:18:26Z

RealHumanBean: /* Idler */

A tensioner is a device that applies force to maintain tension. They are used to reduce slack created in [[Chain Drive|chain drive]] and belt drive mechanisms.
==Shims==
[[File:Shimmed chain tensioner1.png|right|middle|thumb|Shimmed Chain Tensioner]]design judges HATE him most structurally sound most smoothbrain likely the lightest[citation needed] -assembly +weight 
-get laughed at by design judges bc they are all biased against it smh my head
 
==Idler==
Another sprocket or pulley is used to add tension to the chain or belt. It does not add any torque to the system and freely spins.
[[File:Idler chain tensioner1.png|right|middle|thumb|Idler Chain Tensioner]]
<brclear=all />

==Guide==
Chain guides use a durable low friction material to squeeze the chain into tension. This is most commonly used for timing chains (kept lubricated inside the engine) and sometimes on bicycles
[[File:Guide chain tensioner1.png|right|middle|thumb|Guide Chain Tensioner]]
<ref>https://www.specialized.com/us/en/stumpjumper-fsr-comp-evo/p/49715</ref>.
 
==Eccentric==
big brain time +rigidity +infinite adjustability if using friction (may slip) -design complexity -limited finite number of tensioning options if using shear pins[[File:Eccentric chain tensioner2.png|right|middle|thumb|Eccentric Chain Tensioner]]
 
==Turnbuckle==
-play-wear-packaging -rigidity[citation needed] +infinite adjustability can be done w coarse/fine pitch instead of handedness (i completely forgot what the name is for this kind of turnbuckle, but they have less wear/play [citation needed] but allow a smaller range of motion)[[File:Turnbuckle chain tensioner1.png|right|middle|thumb|Turnbuckle Chain Tensioner]]
 
==References==
<references />
[[Category:Internal Combustion]][[Category:Electric Vehicle]]

Tensioner

2020-06-13T05:18:05Z

RealHumanBean: /* Idler */

A tensioner is a device that applies force to maintain tension. They are used to reduce slack created in [[Chain Drive|chain drive]] and belt drive mechanisms.
==Shims==
[[File:Shimmed chain tensioner1.png|right|middle|thumb|Shimmed Chain Tensioner]]design judges HATE him most structurally sound most smoothbrain likely the lightest[citation needed] -assembly +weight 
-get laughed at by design judges bc they are all biased against it smh my head
 
==Idler==
Another sprocket or pulley is used to add tension to the chain or belt. It does not add any torque to the system and freely spins. A spring loaded chain tension is used to tension the chain connecting the crankshaft and camshaft in the 600rr motorcycle engine for example.
[[File:Idler chain tensioner1.png|right|middle|thumb|Idler Chain Tensioner]]
<brclear=all />

==Guide==
Chain guides use a durable low friction material to squeeze the chain into tension. This is most commonly used for timing chains (kept lubricated inside the engine) and sometimes on bicycles
[[File:Guide chain tensioner1.png|right|middle|thumb|Guide Chain Tensioner]]
<ref>https://www.specialized.com/us/en/stumpjumper-fsr-comp-evo/p/49715</ref>.
 
==Eccentric==
big brain time +rigidity +infinite adjustability if using friction (may slip) -design complexity -limited finite number of tensioning options if using shear pins[[File:Eccentric chain tensioner2.png|right|middle|thumb|Eccentric Chain Tensioner]]
 
==Turnbuckle==
-play-wear-packaging -rigidity[citation needed] +infinite adjustability can be done w coarse/fine pitch instead of handedness (i completely forgot what the name is for this kind of turnbuckle, but they have less wear/play [citation needed] but allow a smaller range of motion)[[File:Turnbuckle chain tensioner1.png|right|middle|thumb|Turnbuckle Chain Tensioner]]
 
==References==
<references />
[[Category:Internal Combustion]][[Category:Electric Vehicle]]

Exhaust

2020-06-13T05:15:50Z

RealHumanBean:

The '''exhaust''' system is designed to aid in the removal of burnt fuel and air from the engine. A sound limit is placed on the exhaust in competition. we should also talk about header clocking by firing order into the collector - for scavenging goodness. Scavenging matters because ideally we would have a reversible and adiabatic expansion of the exhaust gases in the cylinder from the maximum cycle pressure to the ambient atmospheric pressure during the power stroke. If the gas is leaving the cylinder at some elevated pressure because of the pressure drop throughout the exhaust system, the potential expansion work relative to the ambient pressure is wasted and the engine power is reduced.

[[File:Exhaust diagram.PNG|thumb|Exhaust System]] 
==Exhaust Form Factors==
The exhaust form factor should drop out of your design constraints (e.g. packaging and weight) as well as your engine system model. There is no one right answer for the best exhaust system.[[File:Exhaust mounting diagram.PNG|thumb|Exhaust Mounting]]
===4-1 ===
===4-2-1 ===
===4-2===
===4-4===
(never seen 4-4 but it'd be sweet. A drawback would be having to include 4 mufflers).
==Silencers and Noise test==
===Muffler/Silencer===
A muffler (or silencer) is an acoustical filter designed to ensure appropriate noise control in the exhaust system of an internal combustion engine.
==Tuning==
===Runner Lengths===
Just do a parametric study in WAVE or GT-Power to determine runner lengths. Because of the high temperatures and pressures involved, reduced order models such as Helmholtz (a linear acoustic model) start to break down. A key quality control during manufacturing should be maintaining equal runner lengths for each stage of the exhaust and minimizing flowpath disruptions due to weld beads or tube misalignment.
===Helmholtz===
[[Category: Internal Combustion]]

User:RealHumanBean

2020-06-09T02:00:21Z

RealHumanBean: Created page with "PM me on this I guess if you want more info. I'll be happy to answer technical questions but perhaps less so with regards to my personal information ...."

PM me on this I guess if you want more info. I'll be happy to answer technical questions but perhaps less so with regards to my personal information ....

Oil

2020-06-09T01:58:50Z

RealHumanBean: /* Dry Sump */

==Basic Purpose of Oil==
==System design==
===Wet Sump===
====[[File:Wet sump.PNG|none|middle|thumb|Wet Sump Schematic]]====

===Banking in Engines===
[[File:Oil system.PNG|right|middle|thumb|Oil System Differences]]
In a stock motorcycle engine, the oil is stored in the oil pan as an internal oil pan. This is called a “wet sump” oil system. On a motorcycle, this works during hard lateral turns because the motorcycle itself leans into the turn, allowing the oil pickup to remain submerged during the turn. In a four wheeled vehicle, the engine cannot tilt into the turn, and the oil is forced against the side of the pan.

====Accumulator====

===Dry Sump===
[[File:Dry sump.PNG|right|middle|thumb|Dry Sump Schematic]]

In a dry sump oil system, the oil for the engine is stored in an external reservoir. The oil that collects at the bottom of the engine is quickly removed by a scavenging pump, and routed into the external reservoir from which the supplies for the engine and the turbocharger are drawn. A common industry solution, a dry sump is often used in very high performance engines for a variety of reasons, including reducing the load on the engine by pumping the oil electrically, or reducing the frictional work the engine has to overcome by reducing windage. A key advantage of a dry sump for FSAE is that the pan thickness can be much smaller due to the external reservoir replacing the wet sump. This in one dramatic swoop eliminates both the oil starvation problem during cornering and allows for reduced center of gravity by bringing the engine which is exceptionally heavy closer to the ground. A dry sump is common in FSAE for forced induction applications as high lateral accelerations reached in the FSAE competition greatly increase the chances of temporary oil starvation of the turbocharger[https://dspace.mit.edu/handle/1721.1/36310].

==Oiling for Turbochargers==
The engine has a robust internal oil management and supply system, so a brief or inconsistent oil supply will have limited consequences for the engine itself. However, the turbocharger is spinning at well over 200,000 rpm, meaning even a small perturbation in oil supply will spell disaster for the bearing system. [citation needed, our source this in our senior proj was alumni communications]
[[category: Internal Combustion]]

Exhaust

2020-06-09T01:52:30Z

RealHumanBean: /* Runner Lengths */

The '''exhaust''' system is designed to aid in the removal of burnt fuel and air from the engine. A sound limit is placed on the exhaust in competition. 
we should also talk about header clocking by firing order into the collector - for scavenging goodness, we actually need way more on scavenging, this page is deserted

[[File:Exhaust diagram.PNG|thumb|Exhaust System]] 
backpressure is a meme
==Exhaust Form Factors==
The exhaust form factor should drop out of your design constraints (e.g. packaging and weight) as well as your engine system model. There is no one right answer for the best exhaust system.[[File:Exhaust mounting diagram.PNG|thumb|Exhaust Mounting]]
===4-1 ===
===4-2-1===

===4-2===

===4-4===
(never seen 4-4 but it'd be sweet. A drawback would be having to include 4 mufflers).

==Silencers and Noise test==
===Muffler/Silencer===

A muffler (or silencer) is an acoustical filter designed to ensure appropriate noise control in the exhaust system of an internal combustion engine.

==Tuning==
===Runner Lengths===

Just do a parametric study in WAVE or GT-Power to determine runner lengths. Because of the high temperatures and pressures involved, reduced order models such as Helmholtz (a linear acoustic model) start to break down. A key quality control during manufacturing should be maintaining equal runner lengths for each stage of the exhaust and minimizing flowpath disruptions due to weld beads or tube misalignment.

===Helmholtz===
[[Category: Internal Combustion]]

Exhaust

2020-06-09T01:50:19Z

RealHumanBean: /* Exhaust Form Factors */

Engine Control

2020-06-09T01:48:27Z

RealHumanBean: /* stuff you should get so you can figure out wth ur doing */

==Theory==
===Passive===
It is possible to run an engine without an engine control module.
Wasted spark such as yamaha wr450 before 2010
cbr is carb stock
===Active===
control spark - timing
control fuel - timing, duration (can't really change angle or placement so we put that under fuel system design, not here)
control air - throttle
control temperature - radiator redirect valve, fan control
control valve timing, valve lift (not electronically tunable, but still control, i'd be willing to put this under intake if that's a better place)
==Tuning==
Engine tuning is the idea of changing the inputs to the engine to achieve a desired goal. The inputs available to tune depend on the engine control strategy. Usually this goal is peak engine torque at every operating condition. The two main inputs used to tune the engine are when charge ignition timing by changing the timing of the spark and quantity of fuel injected by changing the duration that the fuel injector is open. These two inputs are changed depending on the engine operating point: the torque requested (load) and the rotational speed of the engine. The spark timing and fuel duration will each form a 3D surface when plotted against speed and load. (pic)
===Engine Control Strategies===
====Alpha-n====
The most common engine control strategy (at least in fsae, not sure about the galaxy brains across the pond) is alpha-n. Alpha-n tune uses the throttle position angle (<math> \alpha </math> ) to approximate engine load. Use of throttle position to approximate engine load requires ("""""requires""""" we all know most of us dont do this as much as we should lol) compensation for barometric pressure changes. There is really a continuity between using throttle position exclusively and MAP exclusively for engine control. 
=====Advantages=====
This is a direct interpretation of what the driver wants. WOT? You are getting a lot of gas. Idle position? You aren't getting any gas.
=====Drawbacks=====
This is throttle body dependent: change how your throttle is setup and your map is basically bunk unless you spend a lot of time getting it aligned with what you had.

====Speed-Density====
There is also speed-density.
=====Advantages=====
=====Drawbacks=====
====MAF Control====
Not sure if there's a fancy name for maf control, not sure if anyone uses it either.
=====Advantages=====
=====Drawbacks=====

==Theory==
===Dithering===
need to make this clearer
Since the engine torque output is a non-linear function of many variables, and the resultant surface isn't analytically determinate, the torque surface is navigated by dithering. This involves running the engine on a dynamometer and, for each engine control variable, taking small steps in a direction and determining the effect the small step has on the torque. If the result is a decrease in torque, another direction is pursed. By chasing the direction of increasing torque for every operating condition, the engine control is optimized. this is just one big gradient ascent, but very badass.
===Open vs. Closed Loop Tuning===
open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM. Closed loop control can be very powerful, but suffers in throttle transients, which is where FS cars spend a lot of time. Open loop control is an explicit formulation for fuel and spark based on throttle position, MAP, and pretty much everything besides Lambda. One dyno guy I talked to said that his drag cars run in open loop all the time. Correspondence with the ECU OEM I was working with noted that open loop is the first thing you should get down, and closed loop can do the last bit of engine fine control.

===Dynamometer===
see [[:System Testing]]

should have its own page also

===Spark Tuning===
* mbt
[diagram of spark timing on torque]
* Knock is typically not an issue with a stock 4cyl. Not sure how to convey in 10 years of this I have never seen or heard evidence of it.

===Fuel Tuning===
* duration
** lbt
* timing

===Tuning for Startup===
give it a little gaz to get 'er going

===Tuning for Idle===

* Run lean, at least in the case of the 4cyls they do not seem to mind being 15+ [citation needed] 
* Stock CBR idles at ~900RPM, rare that fsae cars run that low. In my experience anything below 2KRPM is a victory. [citation needed]
* Idle air controllers are huge for accurate idle control. [citation needed]
* Sharp pickup on throttle tip-in
* limited spark advance - dont want engine to pick up, keep it stable
* "torque well"
* efficiency - don't waste gas
* idle noise limit

===Tuning For Quick Rev===
==Closed v open loop engine control==

* short term factors
* long term factors
* place in motorsport

=Data and Data Collection=
[link to daq and electronics]
==Data used to run the engine==
(please someone come up with a better title for this section - simon) (needed if not running wasted spark)
* cam sync sensor is needed to determine crank/valve angle - fire spark and fuel on every other rotation
* determine place on fuel/spark map
** load (alpha, map, maf)
** rpm

==Compensations==
* IAT - cooler air is denser and allows for more fuel burn, denser charge may need different spark advance
* map (for alpha-n) - map allows for delays b/w throttle actuation and change in how much air is in intake system, esp with larger plenums, or extreme throttle changes (dump for accel, or complete lift-off)
* coolant temp - warm engine runs more better (afaik fuel vaporization and i know there's other stuff i dont know) but not too hot, can tune to dump fuel to cool engine if its close to overheating though not
* TPS rate compensation for slamming or lift-offs
recommended bc its not efficient

==stuff you should get so you can figure out wth ur doing==
(safety stuff?)
* oil pressure - low op means stop. The relationship between RPM and oil pressure is linear and if it falls off, you are in deep trouble or will be very soon. 
* coolant temp - if its boiling, stop, regulation calls for water which boils at 212 (at normal altitudes @colorado)

==cool data so you can do custom engine stuff==
* cylinder pressure
* knock sensor (cyl pressure can handle this if you have it)
* fuel flow meter
* cyl temperature

I'm sure there's stuff im forgetting
[[Category:Internal Combustion]]

Engine Control

2020-06-09T01:47:16Z

RealHumanBean: /* Tuning for Idle */

==Theory==
===Passive===
It is possible to run an engine without an engine control module.
Wasted spark such as yamaha wr450 before 2010
cbr is carb stock
===Active===
control spark - timing
control fuel - timing, duration (can't really change angle or placement so we put that under fuel system design, not here)
control air - throttle
control temperature - radiator redirect valve, fan control
control valve timing, valve lift (not electronically tunable, but still control, i'd be willing to put this under intake if that's a better place)
==Tuning==
Engine tuning is the idea of changing the inputs to the engine to achieve a desired goal. The inputs available to tune depend on the engine control strategy. Usually this goal is peak engine torque at every operating condition. The two main inputs used to tune the engine are when charge ignition timing by changing the timing of the spark and quantity of fuel injected by changing the duration that the fuel injector is open. These two inputs are changed depending on the engine operating point: the torque requested (load) and the rotational speed of the engine. The spark timing and fuel duration will each form a 3D surface when plotted against speed and load. (pic)
===Engine Control Strategies===
====Alpha-n====
The most common engine control strategy (at least in fsae, not sure about the galaxy brains across the pond) is alpha-n. Alpha-n tune uses the throttle position angle (<math> \alpha </math> ) to approximate engine load. Use of throttle position to approximate engine load requires ("""""requires""""" we all know most of us dont do this as much as we should lol) compensation for barometric pressure changes. There is really a continuity between using throttle position exclusively and MAP exclusively for engine control. 
=====Advantages=====
This is a direct interpretation of what the driver wants. WOT? You are getting a lot of gas. Idle position? You aren't getting any gas.
=====Drawbacks=====
This is throttle body dependent: change how your throttle is setup and your map is basically bunk unless you spend a lot of time getting it aligned with what you had.

====Speed-Density====
There is also speed-density.
=====Advantages=====
=====Drawbacks=====
====MAF Control====
Not sure if there's a fancy name for maf control, not sure if anyone uses it either.
=====Advantages=====
=====Drawbacks=====

==Theory==
===Dithering===
need to make this clearer
Since the engine torque output is a non-linear function of many variables, and the resultant surface isn't analytically determinate, the torque surface is navigated by dithering. This involves running the engine on a dynamometer and, for each engine control variable, taking small steps in a direction and determining the effect the small step has on the torque. If the result is a decrease in torque, another direction is pursed. By chasing the direction of increasing torque for every operating condition, the engine control is optimized. this is just one big gradient ascent, but very badass.
===Open vs. Closed Loop Tuning===
open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM. Closed loop control can be very powerful, but suffers in throttle transients, which is where FS cars spend a lot of time. Open loop control is an explicit formulation for fuel and spark based on throttle position, MAP, and pretty much everything besides Lambda. One dyno guy I talked to said that his drag cars run in open loop all the time. Correspondence with the ECU OEM I was working with noted that open loop is the first thing you should get down, and closed loop can do the last bit of engine fine control.

===Dynamometer===
see [[:System Testing]]

should have its own page also

===Spark Tuning===
* mbt
[diagram of spark timing on torque]
* Knock is typically not an issue with a stock 4cyl. Not sure how to convey in 10 years of this I have never seen or heard evidence of it.

===Fuel Tuning===
* duration
** lbt
* timing

===Tuning for Startup===
give it a little gaz to get 'er going

===Tuning for Idle===

* Run lean, at least in the case of the 4cyls they do not seem to mind being 15+ [citation needed] 
* Stock CBR idles at ~900RPM, rare that fsae cars run that low. In my experience anything below 2KRPM is a victory. [citation needed]
* Idle air controllers are huge for accurate idle control. [citation needed]
* Sharp pickup on throttle tip-in
* limited spark advance - dont want engine to pick up, keep it stable
* "torque well"
* efficiency - don't waste gas
* idle noise limit

===Tuning For Quick Rev===
==Closed v open loop engine control==

* short term factors
* long term factors
* place in motorsport

=Data and Data Collection=
[link to daq and electronics]
==Data used to run the engine==
(please someone come up with a better title for this section - simon) (needed if not running wasted spark)
* cam sync sensor is needed to determine crank/valve angle - fire spark and fuel on every other rotation
* determine place on fuel/spark map
** load (alpha, map, maf)
** rpm

==Compensations==
* IAT - cooler air is denser and allows for more fuel burn, denser charge may need different spark advance
* map (for alpha-n) - map allows for delays b/w throttle actuation and change in how much air is in intake system, esp with larger plenums, or extreme throttle changes (dump for accel, or complete lift-off)
* coolant temp - warm engine runs more better (afaik fuel vaporization and i know there's other stuff i dont know) but not too hot, can tune to dump fuel to cool engine if its close to overheating though not
* TPS rate compensation for slamming or lift-offs
recommended bc its not efficient

==stuff you should get so you can figure out wth ur doing==
(safety stuff?)
* oil pressure - low op means stop
* coolant temp - if its boiling, stop, regulation calls for water which boils at 212 (at normal altitudes @colorado)
==cool data so you can do custom engine stuff==
* cylinder pressure
* knock sensor (cyl pressure can handle this if you have it)
* fuel flow meter
* cyl temperature

I'm sure there's stuff im forgetting
[[Category:Internal Combustion]]

Engine Control

2020-06-09T01:46:28Z

RealHumanBean: /* Open vs. Closed Loop Tuning */

==Theory==
===Passive===
It is possible to run an engine without an engine control module.
Wasted spark such as yamaha wr450 before 2010
cbr is carb stock
===Active===
control spark - timing
control fuel - timing, duration (can't really change angle or placement so we put that under fuel system design, not here)
control air - throttle
control temperature - radiator redirect valve, fan control
control valve timing, valve lift (not electronically tunable, but still control, i'd be willing to put this under intake if that's a better place)
==Tuning==
Engine tuning is the idea of changing the inputs to the engine to achieve a desired goal. The inputs available to tune depend on the engine control strategy. Usually this goal is peak engine torque at every operating condition. The two main inputs used to tune the engine are when charge ignition timing by changing the timing of the spark and quantity of fuel injected by changing the duration that the fuel injector is open. These two inputs are changed depending on the engine operating point: the torque requested (load) and the rotational speed of the engine. The spark timing and fuel duration will each form a 3D surface when plotted against speed and load. (pic)
===Engine Control Strategies===
====Alpha-n====
The most common engine control strategy (at least in fsae, not sure about the galaxy brains across the pond) is alpha-n. Alpha-n tune uses the throttle position angle (<math> \alpha </math> ) to approximate engine load. Use of throttle position to approximate engine load requires ("""""requires""""" we all know most of us dont do this as much as we should lol) compensation for barometric pressure changes. There is really a continuity between using throttle position exclusively and MAP exclusively for engine control. 
=====Advantages=====
This is a direct interpretation of what the driver wants. WOT? You are getting a lot of gas. Idle position? You aren't getting any gas.
=====Drawbacks=====
This is throttle body dependent: change how your throttle is setup and your map is basically bunk unless you spend a lot of time getting it aligned with what you had.

====Speed-Density====
There is also speed-density.
=====Advantages=====
=====Drawbacks=====
====MAF Control====
Not sure if there's a fancy name for maf control, not sure if anyone uses it either.
=====Advantages=====
=====Drawbacks=====

==Theory==
===Dithering===
need to make this clearer
Since the engine torque output is a non-linear function of many variables, and the resultant surface isn't analytically determinate, the torque surface is navigated by dithering. This involves running the engine on a dynamometer and, for each engine control variable, taking small steps in a direction and determining the effect the small step has on the torque. If the result is a decrease in torque, another direction is pursed. By chasing the direction of increasing torque for every operating condition, the engine control is optimized. this is just one big gradient ascent, but very badass.
===Open vs. Closed Loop Tuning===
open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM. Closed loop control can be very powerful, but suffers in throttle transients, which is where FS cars spend a lot of time. Open loop control is an explicit formulation for fuel and spark based on throttle position, MAP, and pretty much everything besides Lambda. One dyno guy I talked to said that his drag cars run in open loop all the time. Correspondence with the ECU OEM I was working with noted that open loop is the first thing you should get down, and closed loop can do the last bit of engine fine control.

===Dynamometer===
see [[:System Testing]]

should have its own page also

===Spark Tuning===
* mbt
[diagram of spark timing on torque]
* Knock is typically not an issue with a stock 4cyl. Not sure how to convey in 10 years of this I have never seen or heard evidence of it.

===Fuel Tuning===
* duration
** lbt
* timing

===Tuning for Startup===
give it a little gaz to get 'er going

===Tuning for Idle===

* Run lean, at least in the case of the 4cyls they do not seem to mind being 15+ [citation needed] 
* Stock CBR idles at ~900RPM, rare that fsae cars run that low [citation needed]
* Idle air controllers are huge for accurate idle control. [citation needed]
* Sharp pickup on throttle tip-in
* limited spark advance - dont want engine to pick up, keep it stable
* "torque well"
* efficiency - don't waste gas
* idle noise limit

===Tuning For Quick Rev===
==Closed v open loop engine control==

* short term factors
* long term factors
* place in motorsport

=Data and Data Collection=
[link to daq and electronics]
==Data used to run the engine==
(please someone come up with a better title for this section - simon) (needed if not running wasted spark)
* cam sync sensor is needed to determine crank/valve angle - fire spark and fuel on every other rotation
* determine place on fuel/spark map
** load (alpha, map, maf)
** rpm

==Compensations==
* IAT - cooler air is denser and allows for more fuel burn, denser charge may need different spark advance
* map (for alpha-n) - map allows for delays b/w throttle actuation and change in how much air is in intake system, esp with larger plenums, or extreme throttle changes (dump for accel, or complete lift-off)
* coolant temp - warm engine runs more better (afaik fuel vaporization and i know there's other stuff i dont know) but not too hot, can tune to dump fuel to cool engine if its close to overheating though not
* TPS rate compensation for slamming or lift-offs
recommended bc its not efficient

==stuff you should get so you can figure out wth ur doing==
(safety stuff?)
* oil pressure - low op means stop
* coolant temp - if its boiling, stop, regulation calls for water which boils at 212 (at normal altitudes @colorado)
==cool data so you can do custom engine stuff==
* cylinder pressure
* knock sensor (cyl pressure can handle this if you have it)
* fuel flow meter
* cyl temperature

I'm sure there's stuff im forgetting
[[Category:Internal Combustion]]

Engine Control

2020-06-09T01:43:27Z

RealHumanBean: /* Alpha-n */

==Theory==
===Passive===
It is possible to run an engine without an engine control module.
Wasted spark such as yamaha wr450 before 2010
cbr is carb stock
===Active===
control spark - timing
control fuel - timing, duration (can't really change angle or placement so we put that under fuel system design, not here)
control air - throttle
control temperature - radiator redirect valve, fan control
control valve timing, valve lift (not electronically tunable, but still control, i'd be willing to put this under intake if that's a better place)
==Tuning==
Engine tuning is the idea of changing the inputs to the engine to achieve a desired goal. The inputs available to tune depend on the engine control strategy. Usually this goal is peak engine torque at every operating condition. The two main inputs used to tune the engine are when charge ignition timing by changing the timing of the spark and quantity of fuel injected by changing the duration that the fuel injector is open. These two inputs are changed depending on the engine operating point: the torque requested (load) and the rotational speed of the engine. The spark timing and fuel duration will each form a 3D surface when plotted against speed and load. (pic)
===Engine Control Strategies===
====Alpha-n====
The most common engine control strategy (at least in fsae, not sure about the galaxy brains across the pond) is alpha-n. Alpha-n tune uses the throttle position angle (<math> \alpha </math> ) to approximate engine load. Use of throttle position to approximate engine load requires ("""""requires""""" we all know most of us dont do this as much as we should lol) compensation for barometric pressure changes. There is really a continuity between using throttle position exclusively and MAP exclusively for engine control. 
=====Advantages=====
This is a direct interpretation of what the driver wants. WOT? You are getting a lot of gas. Idle position? You aren't getting any gas.
=====Drawbacks=====
This is throttle body dependent: change how your throttle is setup and your map is basically bunk unless you spend a lot of time getting it aligned with what you had.

====Speed-Density====
There is also speed-density.
=====Advantages=====
=====Drawbacks=====
====MAF Control====
Not sure if there's a fancy name for maf control, not sure if anyone uses it either.
=====Advantages=====
=====Drawbacks=====

==Theory==
===Dithering===
need to make this clearer
Since the engine torque output is a non-linear function of many variables, and the resultant surface isn't analytically determinate, the torque surface is navigated by dithering. This involves running the engine on a dynamometer and, for each engine control variable, taking small steps in a direction and determining the effect the small step has on the torque. If the result is a decrease in torque, another direction is pursed. By chasing the direction of increasing torque for every operating condition, the engine control is optimized. this is just one big gradient ascent, but very badass.
===Open vs. Closed Loop Tuning===
open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM.
===Dynamometer===
see [[:System Testing]]

should have its own page also

===Spark Tuning===
* mbt
[diagram of spark timing on torque]
* Knock is typically not an issue with a stock 4cyl. Not sure how to convey in 10 years of this I have never seen or heard evidence of it.

===Fuel Tuning===
* duration
** lbt
* timing

===Tuning for Startup===
give it a little gaz to get 'er going

===Tuning for Idle===

* Run lean, at least in the case of the 4cyls they do not seem to mind being 15+ [citation needed] 
* Stock CBR idles at ~900RPM, rare that fsae cars run that low [citation needed]
* Idle air controllers are huge for accurate idle control. [citation needed]
* Sharp pickup on throttle tip-in
* limited spark advance - dont want engine to pick up, keep it stable
* "torque well"
* efficiency - don't waste gas
* idle noise limit

===Tuning For Quick Rev===
==Closed v open loop engine control==

* short term factors
* long term factors
* place in motorsport

=Data and Data Collection=
[link to daq and electronics]
==Data used to run the engine==
(please someone come up with a better title for this section - simon) (needed if not running wasted spark)
* cam sync sensor is needed to determine crank/valve angle - fire spark and fuel on every other rotation
* determine place on fuel/spark map
** load (alpha, map, maf)
** rpm

==Compensations==
* IAT - cooler air is denser and allows for more fuel burn, denser charge may need different spark advance
* map (for alpha-n) - map allows for delays b/w throttle actuation and change in how much air is in intake system, esp with larger plenums, or extreme throttle changes (dump for accel, or complete lift-off)
* coolant temp - warm engine runs more better (afaik fuel vaporization and i know there's other stuff i dont know) but not too hot, can tune to dump fuel to cool engine if its close to overheating though not
* TPS rate compensation for slamming or lift-offs
recommended bc its not efficient

==stuff you should get so you can figure out wth ur doing==
(safety stuff?)
* oil pressure - low op means stop
* coolant temp - if its boiling, stop, regulation calls for water which boils at 212 (at normal altitudes @colorado)
==cool data so you can do custom engine stuff==
* cylinder pressure
* knock sensor (cyl pressure can handle this if you have it)
* fuel flow meter
* cyl temperature

I'm sure there's stuff im forgetting
[[Category:Internal Combustion]]

Engine

2020-06-09T01:40:36Z

RealHumanBean: /* Common Engines */

The engine is the center of the internal combustion powertrain system. All other components of the greater system exist to service the engine in different ways. This means the engine is sensitive to design changes made across the entire powertrain.As of 2019, the FSAE rules require an internal combustion engine with a displacement of 710cc or less. Available OEM motors within this displacement limit are largely sourced from motorcycles and snowmobiles. The purpose of an internal combustion engine is to convert the chemical energy in gasoline or ethanol into mechanical energy used to propel the car. The engine is one of the most complicated single parts of any vehicle. The engine is often the heaviest single part of an internal combustion vehicle.

Please take a look at the outline in the discussion section before making changes to this page

=Theory=
{{Main|Otto Cycle}}
=Structure=
I think wikipedia does a very detailed explanation on general engine layout, i think we should probably focus on bike engines w.r.t. fsae competitions.

Engine configuration is a case where the 80/20 rule really applies: the last bit of effort really doesn't get you too much. The bike engines are supersport engines and already configured to perform at a high level (albeit with a bike transmission and unrestricted intake). Removing first gear and some of the higher gears and using a dedicated racing clutch are probably the lowest hanging fruits with regards to the actual engine itself. A custom oil pan is likely essential for many engines due to packaging but a custom wet sump will lack any moving parts.

The structure and operation of motorcycle engines differs from typical car engines in a few key places: size, layout, redline bb. Engines used in these competitions are all under 150 lbs with 600cc 4 cyl coming in at about 125-140, depending on brand or custom parts. Single cylinder engines typically weigh in the neighborhood of 70-90 pounds. These engines are almost exclusively overhead cam layout.

structure: cams, ports, valves, cylinder, piston, conrods/crank, oil and wp, case and covers.
crossflow cylinder discussion?
Yamaha yzf that have intake in front and exhaust in the rear - contrast to every other engine

I dont know anything about snowmobile engines so someone else is gonna have to do that.

=Engine Control=
{{Main|Engine control}}

Most modern engines are controlled by an engine control module (ECM) that determines when to inject the fuel and when to ignite the charge using various sensors and an engine tune.

=Goals=
==Reliability==
If the engine finishes endurance, it was reliable. (to some teams, to others, maybe they need one engine to last many years due to budget constraints or the fact that they're running an aprillia and there's only two in the US)

Michael Royce in Learn & Compete states that “[reliability] must be the number one technical objective of the team”.

Engine to engine comparisons are difficult, and the literature is sparse at best. Most available engine specific reliability reports are anecdotal. However, brand comparisons are both easier and more widely available. Consumer Reports performed such a comprehensive [https://www.consumerreports.org/cro/news/2015/04/who-makes-the-most-reliable-motorcycle/index.htm study] on motorcycle reliability. The reliability study is focused on how often the bikes would need to have repairs within the first four years of purchase. The three big Japanese motorcycle companies, Yamaha, Suzuki, and Honda, are the only three with under 15% of the bikes with repairs needed. Yamaha leads the brands with 11% compared to the 12% for Honda and Suzuki each. It is important to consider that this study included the bike as a whole, and that for all of the studied motorcycles“mechanical engine problems were relatively rare, with only 3 percent having trouble with the cylinder head or valvetrain, or with the crankcase, crankshaft, or pistons. Similarly, only 3 percent needed transmission repairs, although 7 percent had clutch problems.” LA Times [citation needed] researching this study reported an interview stating "European bikes are engineered for character and sex appeal, and Japanese bikes are engineered for reliability,". This sentiment can be found echoed in the FSAE online forums. Another aspect of reliability is parts and tools availability. If something breaks, how easy is it to get hold of spare parts quickly in order to fix the engine? Do you need special tools to service the engine, and can you buy, borrow or manufacture these?

==Power/Torque==
An obvious goal of an engine is to produce enough power to accomplish your designed team goals. How much is enough? What RPM should we make peak power? Torque? To all of these questions, it depends heavily upon your team's design philosophy. All could be relatively determined from a rudimentary laptime simulation, but will need to be confirmed via testing. Also worth noting theory on how to determine ideal peak power position (histogram of engine speeds, peak torque at roughly that speed. Can also loosely perform an "integral" by multiplying engine speed occurrences with the power output at that point as when the integral is maximized, the most power was put down to the track)

I imagine there is a lot more to expand upon here - Novotny

Examples of teams design philosophy:
* we have a novice driver - we want our torque curve to be wide and flat
* we run a CVT and the engine will hold at a specific RPM during all events and we only want torque at that spot at the expense of all else
* we are a first year team and we dont know what we are doing so we are just going for peak torque everywhere
* we have the torque curve in the shape we want so we are just tuning for peak torque everywhere
* we are running with huge boost and need to run with an AFR of 9 or else we'll be building a bomb
* we can't get our engine to idle, so we're spending the whole year tuning at 1.5K RPM and didn't get around to anything else
* our driver is a 4th year masters student who has 8 years of FS driving and can put the engine wherever he wants, we are giving him peak torque at 9650 RPM because thats what gives him the fasted lap times during testing

Torque and power are determined by testing the engine on a dynomometer (need page for dynos).
===Power Limiting Factors===
====Restrictor====
====Piston Speed Limit====
"a. Automotive / Motorcycle engines 914.4 m/min (3,000 ft/min) 
b. Industrial Engines 731.5 m/min (2,400 ft/min) 
The calculated speed will be rounded to the nearest 500 rpm." 
test speeds - http://fsaeonline.com/content/Noise%20Test%20Speeds%202015.pdf 
[100% VE v choked flow graph for cbr example?] 
Back of envelope calc for CBR at 11K 
599cc four cyl 
4 stroke means 2 cyl per rev 
299.5 cc per rev 
3294.5 L per min at 11K rpm 
using air at 25C, 0psig (no boost, 100% VE) 
1.2 kg air per m3 [https://www.engineeringtoolbox.com/air-temperature-pressure-density-d_771.html] 
0.0012 kg_air/L 
3.9534 kg/min at 11K rpm 
0.06589 kg/s at 11K rpm 
assuming an afr of 13.1 [citation needed] 
0.00503 kg_gasoline/sec at 11K rpm 
Q_LHV of gasoline is 46e3 kJ/kg fuel 
231 kJ/s or kW at 11K rpm 
somehow "proves" 100% VE for honda CBR600RR shouldn't even be restricted by the restrictor - this becomes a bruh moment. 

==Efficiency==
high speed low drag babey
=Simulation=
[[Otto Cycle|otto cycle]] matlab sims for freshmen

==1D engine sims==
Ricardo WAVE or GT-Power are commonly used. I (and the guy who I edited over) have had good success with Ricardo. From my experience, WAVE is good for understanding trends, but not necessarily getting a precise power number. The 1D model is especially suspect for the highly 3D behavior you see with the restrictor and plenum. The strength really lies in getting an engineering understanding of how to design an intake and exhaust for a given torque curve e.g. how long should I make my runners, do I run a 4-2-1 or a 4-1 exhaust, and how large should my plenum be.

==3D flame propogation sims in advanced research labs==
Just use a dynamometer or WAVE. 3D combustion CFD is really nasty and without experiments to support your model it is suspect.

=Oil System=
{{Main|Oil}}
=Mounting System=
Vibration Reduction
=Best Practices=
How to care for an engine.

How/when to service.

How to diagnose issues.

Why combustion is more romantic than electric.
=Common Engines=
I think bc the cbr, r6, and a few of the 450s are so common, we can use this to list what we have done to optimize for FSAE use.

Example: gear removal, EWP, custom valving, suggested idles, mounting tips, weights/mass, stock water pump flow rates, oil recomendations, intake mounting recs. exhaust mounting recs, heat generation, wiring, injectors

Honda CBR 600RR
* remove first gear, breaks traction with any reasonable FDR
* max heat dissipation of ~10kW needed from cooling system (utoronto 2007 - https://manualzz.com/doc/35576578/design-and-optimzation-of-a-formula-sae-cooling)
* remove the thermostat control to keep temps down (this is something I am skeptical of. The thermal mass of the engine and cooling circuit is high enough that you won't get into trouble running the OEM thermostat if the cooling system operates correctly, and the engine is happier when it is at temperature. This is a relatively minor modification so running a lap with and without could be a decent test) 

Yamaha R6

Yamaha WR/YZ450
* WPI runs WiSECO high compression piston

see all engines [[List of Engines|here]][[Category: Internal Combustion]]

Engine

2020-06-09T01:38:21Z

RealHumanBean: /* 3D flame propogation sims in advanced research labs */

The engine is the center of the internal combustion powertrain system. All other components of the greater system exist to service the engine in different ways. This means the engine is sensitive to design changes made across the entire powertrain.As of 2019, the FSAE rules require an internal combustion engine with a displacement of 710cc or less. Available OEM motors within this displacement limit are largely sourced from motorcycles and snowmobiles. The purpose of an internal combustion engine is to convert the chemical energy in gasoline or ethanol into mechanical energy used to propel the car. The engine is one of the most complicated single parts of any vehicle. The engine is often the heaviest single part of an internal combustion vehicle.

Please take a look at the outline in the discussion section before making changes to this page

=Theory=
{{Main|Otto Cycle}}
=Structure=
I think wikipedia does a very detailed explanation on general engine layout, i think we should probably focus on bike engines w.r.t. fsae competitions.

Engine configuration is a case where the 80/20 rule really applies: the last bit of effort really doesn't get you too much. The bike engines are supersport engines and already configured to perform at a high level (albeit with a bike transmission and unrestricted intake). Removing first gear and some of the higher gears and using a dedicated racing clutch are probably the lowest hanging fruits with regards to the actual engine itself. A custom oil pan is likely essential for many engines due to packaging but a custom wet sump will lack any moving parts.

The structure and operation of motorcycle engines differs from typical car engines in a few key places: size, layout, redline bb. Engines used in these competitions are all under 150 lbs with 600cc 4 cyl coming in at about 125-140, depending on brand or custom parts. Single cylinder engines typically weigh in the neighborhood of 70-90 pounds. These engines are almost exclusively overhead cam layout.

structure: cams, ports, valves, cylinder, piston, conrods/crank, oil and wp, case and covers.
crossflow cylinder discussion?
Yamaha yzf that have intake in front and exhaust in the rear - contrast to every other engine

I dont know anything about snowmobile engines so someone else is gonna have to do that.

=Engine Control=
{{Main|Engine control}}

Most modern engines are controlled by an engine control module (ECM) that determines when to inject the fuel and when to ignite the charge using various sensors and an engine tune.

=Goals=
==Reliability==
If the engine finishes endurance, it was reliable. (to some teams, to others, maybe they need one engine to last many years due to budget constraints or the fact that they're running an aprillia and there's only two in the US)

Michael Royce in Learn & Compete states that “[reliability] must be the number one technical objective of the team”.

Engine to engine comparisons are difficult, and the literature is sparse at best. Most available engine specific reliability reports are anecdotal. However, brand comparisons are both easier and more widely available. Consumer Reports performed such a comprehensive [https://www.consumerreports.org/cro/news/2015/04/who-makes-the-most-reliable-motorcycle/index.htm study] on motorcycle reliability. The reliability study is focused on how often the bikes would need to have repairs within the first four years of purchase. The three big Japanese motorcycle companies, Yamaha, Suzuki, and Honda, are the only three with under 15% of the bikes with repairs needed. Yamaha leads the brands with 11% compared to the 12% for Honda and Suzuki each. It is important to consider that this study included the bike as a whole, and that for all of the studied motorcycles“mechanical engine problems were relatively rare, with only 3 percent having trouble with the cylinder head or valvetrain, or with the crankcase, crankshaft, or pistons. Similarly, only 3 percent needed transmission repairs, although 7 percent had clutch problems.” LA Times [citation needed] researching this study reported an interview stating "European bikes are engineered for character and sex appeal, and Japanese bikes are engineered for reliability,". This sentiment can be found echoed in the FSAE online forums. Another aspect of reliability is parts and tools availability. If something breaks, how easy is it to get hold of spare parts quickly in order to fix the engine? Do you need special tools to service the engine, and can you buy, borrow or manufacture these?

==Power/Torque==
An obvious goal of an engine is to produce enough power to accomplish your designed team goals. How much is enough? What RPM should we make peak power? Torque? To all of these questions, it depends heavily upon your team's design philosophy. All could be relatively determined from a rudimentary laptime simulation, but will need to be confirmed via testing. Also worth noting theory on how to determine ideal peak power position (histogram of engine speeds, peak torque at roughly that speed. Can also loosely perform an "integral" by multiplying engine speed occurrences with the power output at that point as when the integral is maximized, the most power was put down to the track)

I imagine there is a lot more to expand upon here - Novotny

Examples of teams design philosophy:
* we have a novice driver - we want our torque curve to be wide and flat
* we run a CVT and the engine will hold at a specific RPM during all events and we only want torque at that spot at the expense of all else
* we are a first year team and we dont know what we are doing so we are just going for peak torque everywhere
* we have the torque curve in the shape we want so we are just tuning for peak torque everywhere
* we are running with huge boost and need to run with an AFR of 9 or else we'll be building a bomb
* we can't get our engine to idle, so we're spending the whole year tuning at 1.5K RPM and didn't get around to anything else
* our driver is a 4th year masters student who has 8 years of FS driving and can put the engine wherever he wants, we are giving him peak torque at 9650 RPM because thats what gives him the fasted lap times during testing

Torque and power are determined by testing the engine on a dynomometer (need page for dynos).
===Power Limiting Factors===
====Restrictor====
====Piston Speed Limit====
"a. Automotive / Motorcycle engines 914.4 m/min (3,000 ft/min) 
b. Industrial Engines 731.5 m/min (2,400 ft/min) 
The calculated speed will be rounded to the nearest 500 rpm." 
test speeds - http://fsaeonline.com/content/Noise%20Test%20Speeds%202015.pdf 
[100% VE v choked flow graph for cbr example?] 
Back of envelope calc for CBR at 11K 
599cc four cyl 
4 stroke means 2 cyl per rev 
299.5 cc per rev 
3294.5 L per min at 11K rpm 
using air at 25C, 0psig (no boost, 100% VE) 
1.2 kg air per m3 [https://www.engineeringtoolbox.com/air-temperature-pressure-density-d_771.html] 
0.0012 kg_air/L 
3.9534 kg/min at 11K rpm 
0.06589 kg/s at 11K rpm 
assuming an afr of 13.1 [citation needed] 
0.00503 kg_gasoline/sec at 11K rpm 
Q_LHV of gasoline is 46e3 kJ/kg fuel 
231 kJ/s or kW at 11K rpm 
somehow "proves" 100% VE for honda CBR600RR shouldn't even be restricted by the restrictor - this becomes a bruh moment. 

==Efficiency==
high speed low drag babey
=Simulation=
[[Otto Cycle|otto cycle]] matlab sims for freshmen

==1D engine sims==
Ricardo WAVE or GT-Power are commonly used. I (and the guy who I edited over) have had good success with Ricardo. From my experience, WAVE is good for understanding trends, but not necessarily getting a precise power number. The 1D model is especially suspect for the highly 3D behavior you see with the restrictor and plenum. The strength really lies in getting an engineering understanding of how to design an intake and exhaust for a given torque curve e.g. how long should I make my runners, do I run a 4-2-1 or a 4-1 exhaust, and how large should my plenum be.

==3D flame propogation sims in advanced research labs==
Just use a dynamometer or WAVE. 3D combustion CFD is really nasty and without experiments to support your model it is suspect.

=Oil System=
{{Main|Oil}}
=Mounting System=
Vibration Reduction
=Best Practices=
How to care for an engine.

How/when to service.

How to diagnose issues.

Why combustion is more romantic than electric.
=Common Engines=
I think bc the cbr, r6, and a few of the 450s are so common, we can use this to list what we have done to optimize for FSAE use.

Example: gear removal, EWP, custom valving, suggested idles, mounting tips, weights/mass, stock water pump flow rates, oil recomendations, intake mounting recs. exhaust mounting recs, heat generation, wiring, injectors

Honda CBR 600RR
* remove first gear, breaks traction with any reasonable FDR
* max heat dissipation of ~10kW needed from cooling system (utoronto 2007 - https://manualzz.com/doc/35576578/design-and-optimzation-of-a-formula-sae-cooling)
* remove the thermostat control to keep temps down

Yamaha R6

Yamaha WR/YZ450
* WPI runs WiSECO high compression piston

see all engines [[List of Engines|here]][[Category: Internal Combustion]]

Engine

2020-06-09T01:37:23Z

RealHumanBean: /* 1D engine sims */

The engine is the center of the internal combustion powertrain system. All other components of the greater system exist to service the engine in different ways. This means the engine is sensitive to design changes made across the entire powertrain.As of 2019, the FSAE rules require an internal combustion engine with a displacement of 710cc or less. Available OEM motors within this displacement limit are largely sourced from motorcycles and snowmobiles. The purpose of an internal combustion engine is to convert the chemical energy in gasoline or ethanol into mechanical energy used to propel the car. The engine is one of the most complicated single parts of any vehicle. The engine is often the heaviest single part of an internal combustion vehicle.

Please take a look at the outline in the discussion section before making changes to this page

=Theory=
{{Main|Otto Cycle}}
=Structure=
I think wikipedia does a very detailed explanation on general engine layout, i think we should probably focus on bike engines w.r.t. fsae competitions.

Engine configuration is a case where the 80/20 rule really applies: the last bit of effort really doesn't get you too much. The bike engines are supersport engines and already configured to perform at a high level (albeit with a bike transmission and unrestricted intake). Removing first gear and some of the higher gears and using a dedicated racing clutch are probably the lowest hanging fruits with regards to the actual engine itself. A custom oil pan is likely essential for many engines due to packaging but a custom wet sump will lack any moving parts.

The structure and operation of motorcycle engines differs from typical car engines in a few key places: size, layout, redline bb. Engines used in these competitions are all under 150 lbs with 600cc 4 cyl coming in at about 125-140, depending on brand or custom parts. Single cylinder engines typically weigh in the neighborhood of 70-90 pounds. These engines are almost exclusively overhead cam layout.

structure: cams, ports, valves, cylinder, piston, conrods/crank, oil and wp, case and covers.
crossflow cylinder discussion?
Yamaha yzf that have intake in front and exhaust in the rear - contrast to every other engine

I dont know anything about snowmobile engines so someone else is gonna have to do that.

=Engine Control=
{{Main|Engine control}}

Most modern engines are controlled by an engine control module (ECM) that determines when to inject the fuel and when to ignite the charge using various sensors and an engine tune.

=Goals=
==Reliability==
If the engine finishes endurance, it was reliable. (to some teams, to others, maybe they need one engine to last many years due to budget constraints or the fact that they're running an aprillia and there's only two in the US)

Michael Royce in Learn & Compete states that “[reliability] must be the number one technical objective of the team”.

Engine to engine comparisons are difficult, and the literature is sparse at best. Most available engine specific reliability reports are anecdotal. However, brand comparisons are both easier and more widely available. Consumer Reports performed such a comprehensive [https://www.consumerreports.org/cro/news/2015/04/who-makes-the-most-reliable-motorcycle/index.htm study] on motorcycle reliability. The reliability study is focused on how often the bikes would need to have repairs within the first four years of purchase. The three big Japanese motorcycle companies, Yamaha, Suzuki, and Honda, are the only three with under 15% of the bikes with repairs needed. Yamaha leads the brands with 11% compared to the 12% for Honda and Suzuki each. It is important to consider that this study included the bike as a whole, and that for all of the studied motorcycles“mechanical engine problems were relatively rare, with only 3 percent having trouble with the cylinder head or valvetrain, or with the crankcase, crankshaft, or pistons. Similarly, only 3 percent needed transmission repairs, although 7 percent had clutch problems.” LA Times [citation needed] researching this study reported an interview stating "European bikes are engineered for character and sex appeal, and Japanese bikes are engineered for reliability,". This sentiment can be found echoed in the FSAE online forums. Another aspect of reliability is parts and tools availability. If something breaks, how easy is it to get hold of spare parts quickly in order to fix the engine? Do you need special tools to service the engine, and can you buy, borrow or manufacture these?

==Power/Torque==
An obvious goal of an engine is to produce enough power to accomplish your designed team goals. How much is enough? What RPM should we make peak power? Torque? To all of these questions, it depends heavily upon your team's design philosophy. All could be relatively determined from a rudimentary laptime simulation, but will need to be confirmed via testing. Also worth noting theory on how to determine ideal peak power position (histogram of engine speeds, peak torque at roughly that speed. Can also loosely perform an "integral" by multiplying engine speed occurrences with the power output at that point as when the integral is maximized, the most power was put down to the track)

I imagine there is a lot more to expand upon here - Novotny

Examples of teams design philosophy:
* we have a novice driver - we want our torque curve to be wide and flat
* we run a CVT and the engine will hold at a specific RPM during all events and we only want torque at that spot at the expense of all else
* we are a first year team and we dont know what we are doing so we are just going for peak torque everywhere
* we have the torque curve in the shape we want so we are just tuning for peak torque everywhere
* we are running with huge boost and need to run with an AFR of 9 or else we'll be building a bomb
* we can't get our engine to idle, so we're spending the whole year tuning at 1.5K RPM and didn't get around to anything else
* our driver is a 4th year masters student who has 8 years of FS driving and can put the engine wherever he wants, we are giving him peak torque at 9650 RPM because thats what gives him the fasted lap times during testing

Torque and power are determined by testing the engine on a dynomometer (need page for dynos).
===Power Limiting Factors===
====Restrictor====
====Piston Speed Limit====
"a. Automotive / Motorcycle engines 914.4 m/min (3,000 ft/min) 
b. Industrial Engines 731.5 m/min (2,400 ft/min) 
The calculated speed will be rounded to the nearest 500 rpm." 
test speeds - http://fsaeonline.com/content/Noise%20Test%20Speeds%202015.pdf 
[100% VE v choked flow graph for cbr example?] 
Back of envelope calc for CBR at 11K 
599cc four cyl 
4 stroke means 2 cyl per rev 
299.5 cc per rev 
3294.5 L per min at 11K rpm 
using air at 25C, 0psig (no boost, 100% VE) 
1.2 kg air per m3 [https://www.engineeringtoolbox.com/air-temperature-pressure-density-d_771.html] 
0.0012 kg_air/L 
3.9534 kg/min at 11K rpm 
0.06589 kg/s at 11K rpm 
assuming an afr of 13.1 [citation needed] 
0.00503 kg_gasoline/sec at 11K rpm 
Q_LHV of gasoline is 46e3 kJ/kg fuel 
231 kJ/s or kW at 11K rpm 
somehow "proves" 100% VE for honda CBR600RR shouldn't even be restricted by the restrictor - this becomes a bruh moment. 

==Efficiency==
high speed low drag babey
=Simulation=
[[Otto Cycle|otto cycle]] matlab sims for freshmen

==1D engine sims==
Ricardo WAVE or GT-Power are commonly used. I (and the guy who I edited over) have had good success with Ricardo. From my experience, WAVE is good for understanding trends, but not necessarily getting a precise power number. The 1D model is especially suspect for the highly 3D behavior you see with the restrictor and plenum. The strength really lies in getting an engineering understanding of how to design an intake and exhaust for a given torque curve e.g. how long should I make my runners, do I run a 4-2-1 or a 4-1 exhaust, and how large should my plenum be.

==3D flame propogation sims in advanced research labs==
=Oil System=
{{Main|Oil}}
=Mounting System=
Vibration Reduction
=Best Practices=
How to care for an engine.

How/when to service.

How to diagnose issues.

Why combustion is more romantic than electric.
=Common Engines=
I think bc the cbr, r6, and a few of the 450s are so common, we can use this to list what we have done to optimize for FSAE use.

Example: gear removal, EWP, custom valving, suggested idles, mounting tips, weights/mass, stock water pump flow rates, oil recomendations, intake mounting recs. exhaust mounting recs, heat generation, wiring, injectors

Honda CBR 600RR
* remove first gear, breaks traction with any reasonable FDR
* max heat dissipation of ~10kW needed from cooling system (utoronto 2007 - https://manualzz.com/doc/35576578/design-and-optimzation-of-a-formula-sae-cooling)
* remove the thermostat control to keep temps down

Yamaha R6

Yamaha WR/YZ450
* WPI runs WiSECO high compression piston

see all engines [[List of Engines|here]][[Category: Internal Combustion]]

Engine

2020-06-09T01:34:13Z

RealHumanBean: /* Structure */

The engine is the center of the internal combustion powertrain system. All other components of the greater system exist to service the engine in different ways. This means the engine is sensitive to design changes made across the entire powertrain.As of 2019, the FSAE rules require an internal combustion engine with a displacement of 710cc or less. Available OEM motors within this displacement limit are largely sourced from motorcycles and snowmobiles. The purpose of an internal combustion engine is to convert the chemical energy in gasoline or ethanol into mechanical energy used to propel the car. The engine is one of the most complicated single parts of any vehicle. The engine is often the heaviest single part of an internal combustion vehicle.

Please take a look at the outline in the discussion section before making changes to this page

=Theory=
{{Main|Otto Cycle}}
=Structure=
I think wikipedia does a very detailed explanation on general engine layout, i think we should probably focus on bike engines w.r.t. fsae competitions.

Engine configuration is a case where the 80/20 rule really applies: the last bit of effort really doesn't get you too much. The bike engines are supersport engines and already configured to perform at a high level (albeit with a bike transmission and unrestricted intake). Removing first gear and some of the higher gears and using a dedicated racing clutch are probably the lowest hanging fruits with regards to the actual engine itself. A custom oil pan is likely essential for many engines due to packaging but a custom wet sump will lack any moving parts.

The structure and operation of motorcycle engines differs from typical car engines in a few key places: size, layout, redline bb. Engines used in these competitions are all under 150 lbs with 600cc 4 cyl coming in at about 125-140, depending on brand or custom parts. Single cylinder engines typically weigh in the neighborhood of 70-90 pounds. These engines are almost exclusively overhead cam layout.

structure: cams, ports, valves, cylinder, piston, conrods/crank, oil and wp, case and covers.
crossflow cylinder discussion?
Yamaha yzf that have intake in front and exhaust in the rear - contrast to every other engine

I dont know anything about snowmobile engines so someone else is gonna have to do that.

=Engine Control=
{{Main|Engine control}}

Most modern engines are controlled by an engine control module (ECM) that determines when to inject the fuel and when to ignite the charge using various sensors and an engine tune.

=Goals=
==Reliability==
If the engine finishes endurance, it was reliable. (to some teams, to others, maybe they need one engine to last many years due to budget constraints or the fact that they're running an aprillia and there's only two in the US)

Michael Royce in Learn & Compete states that “[reliability] must be the number one technical objective of the team”.

Engine to engine comparisons are difficult, and the literature is sparse at best. Most available engine specific reliability reports are anecdotal. However, brand comparisons are both easier and more widely available. Consumer Reports performed such a comprehensive [https://www.consumerreports.org/cro/news/2015/04/who-makes-the-most-reliable-motorcycle/index.htm study] on motorcycle reliability. The reliability study is focused on how often the bikes would need to have repairs within the first four years of purchase. The three big Japanese motorcycle companies, Yamaha, Suzuki, and Honda, are the only three with under 15% of the bikes with repairs needed. Yamaha leads the brands with 11% compared to the 12% for Honda and Suzuki each. It is important to consider that this study included the bike as a whole, and that for all of the studied motorcycles“mechanical engine problems were relatively rare, with only 3 percent having trouble with the cylinder head or valvetrain, or with the crankcase, crankshaft, or pistons. Similarly, only 3 percent needed transmission repairs, although 7 percent had clutch problems.” LA Times [citation needed] researching this study reported an interview stating "European bikes are engineered for character and sex appeal, and Japanese bikes are engineered for reliability,". This sentiment can be found echoed in the FSAE online forums. Another aspect of reliability is parts and tools availability. If something breaks, how easy is it to get hold of spare parts quickly in order to fix the engine? Do you need special tools to service the engine, and can you buy, borrow or manufacture these?

==Power/Torque==
An obvious goal of an engine is to produce enough power to accomplish your designed team goals. How much is enough? What RPM should we make peak power? Torque? To all of these questions, it depends heavily upon your team's design philosophy. All could be relatively determined from a rudimentary laptime simulation, but will need to be confirmed via testing. Also worth noting theory on how to determine ideal peak power position (histogram of engine speeds, peak torque at roughly that speed. Can also loosely perform an "integral" by multiplying engine speed occurrences with the power output at that point as when the integral is maximized, the most power was put down to the track)

I imagine there is a lot more to expand upon here - Novotny

Examples of teams design philosophy:
* we have a novice driver - we want our torque curve to be wide and flat
* we run a CVT and the engine will hold at a specific RPM during all events and we only want torque at that spot at the expense of all else
* we are a first year team and we dont know what we are doing so we are just going for peak torque everywhere
* we have the torque curve in the shape we want so we are just tuning for peak torque everywhere
* we are running with huge boost and need to run with an AFR of 9 or else we'll be building a bomb
* we can't get our engine to idle, so we're spending the whole year tuning at 1.5K RPM and didn't get around to anything else
* our driver is a 4th year masters student who has 8 years of FS driving and can put the engine wherever he wants, we are giving him peak torque at 9650 RPM because thats what gives him the fasted lap times during testing

Torque and power are determined by testing the engine on a dynomometer (need page for dynos).
===Power Limiting Factors===
====Restrictor====
====Piston Speed Limit====
"a. Automotive / Motorcycle engines 914.4 m/min (3,000 ft/min) 
b. Industrial Engines 731.5 m/min (2,400 ft/min) 
The calculated speed will be rounded to the nearest 500 rpm." 
test speeds - http://fsaeonline.com/content/Noise%20Test%20Speeds%202015.pdf 
[100% VE v choked flow graph for cbr example?] 
Back of envelope calc for CBR at 11K 
599cc four cyl 
4 stroke means 2 cyl per rev 
299.5 cc per rev 
3294.5 L per min at 11K rpm 
using air at 25C, 0psig (no boost, 100% VE) 
1.2 kg air per m3 [https://www.engineeringtoolbox.com/air-temperature-pressure-density-d_771.html] 
0.0012 kg_air/L 
3.9534 kg/min at 11K rpm 
0.06589 kg/s at 11K rpm 
assuming an afr of 13.1 [citation needed] 
0.00503 kg_gasoline/sec at 11K rpm 
Q_LHV of gasoline is 46e3 kJ/kg fuel 
231 kJ/s or kW at 11K rpm 
somehow "proves" 100% VE for honda CBR600RR shouldn't even be restricted by the restrictor - this becomes a bruh moment. 

==Efficiency==
high speed low drag babey
=Simulation=
[[Otto Cycle|otto cycle]] matlab sims for freshmen

==1D engine sims==
We used ricardo, not sure how well that transfers to others
==3D flame propogation sims in advanced research labs==
=Oil System=
{{Main|Oil}}
=Mounting System=
Vibration Reduction
=Best Practices=
How to care for an engine.

How/when to service.

How to diagnose issues.

Why combustion is more romantic than electric.
=Common Engines=
I think bc the cbr, r6, and a few of the 450s are so common, we can use this to list what we have done to optimize for FSAE use.

Example: gear removal, EWP, custom valving, suggested idles, mounting tips, weights/mass, stock water pump flow rates, oil recomendations, intake mounting recs. exhaust mounting recs, heat generation, wiring, injectors

Honda CBR 600RR
* remove first gear, breaks traction with any reasonable FDR
* max heat dissipation of ~10kW needed from cooling system (utoronto 2007 - https://manualzz.com/doc/35576578/design-and-optimzation-of-a-formula-sae-cooling)
* remove the thermostat control to keep temps down

Yamaha R6

Yamaha WR/YZ450
* WPI runs WiSECO high compression piston

see all engines [[List of Engines|here]][[Category: Internal Combustion]]

Cooling

2020-06-09T01:30:01Z

RealHumanBean: /* Oil cooling */

More than 50% of energy used in combustion goes into heat[citation needed]. Heat is also generated by the turbulence of the air in the intake and cylinder, as well as friction from the engine's internals. A system is needed to keep the engine within it's operational temperature range.
=Theory=
Cooling systems are designed to dissipate the unwanted thermal energy. Systems are often designed around heat exchangers (HEXs), allowing for efficient exchange of heat from a hot fluid to a cooler one. There are three main methods of heat transfer;
* Conduction: Heat transfer over a temperature differential without motion between the materials
* Convection: Heat transfer over a temperature differential with fluid motion between the materials
* Radiation: Heat transfer due to by energy emitted from the unstable nature of a hot material (shitty definition, but the best I have)
** Heat transfer in the form of electromagnetic radiation emitted by bodies above absolute 0 (wikipedia says its a function of distributing entropy, not sure we're gonna get a simple, and easy answer here)
A heat exchanger (HEX) is normally designed to optimize the heat transfer between two fluids using conduction and convection. The most common HEX is an water to air cooler, meaning it transfers heat between the hot water and the cooler air. These HEXs have a few distinct characteristics, full metal construction, thin metal fins in the streamwise direction, water inlets on top and bottom, with air inlets on the front and back. The metal construction is due to a low conductive heat transfer coefficient within the metal in addition to a low specific heat. These factors allow the metal rapidly conduct heat from the hotter internal water channels to the cooler metal fin tips. Aluminum is nearly universally used in automotive radiators. While materials such as copper may notionally provide more cooling due to higher thermal conductivity, the thermal resistance of aluminum sheet metal is so low that the heat transfer from the water circuit to the air is limited by the convective coefficients. Aluminum also is light and strong as fins or sheets. The fin structure is to maximize convection heat transfer by increasing the surface area the air flows over. The convection heat transfer coefficient is also a function of the airspeed passing the fin, allowing for 'forced convection' where a fan and or vehicle speed is used to impart an inlet speed to the system.Behavior(function?) of radiators vary heavily based upon water channel sizes, fin spacing, and a plethora of other characteristics.
For a more detailed understanding of theory, any heat transfer textbook such as ''Incropera and Dewitt ''will serve. ''Kays and London'''s heat exchanger text is invaluable as a practical reference. It includes heat transfer coefficients for various fin and tube geometries. It is possible to measure the geometry of your radiator's fins, determine what type of fin geometry you are using, and then look up the appropriate set of coefficients for a rather robust heat exchanger model.

=Cooling Power=
The amount of thermal power that the engine puts into the water has to be the same as the thermal power the radiator dissipates ''at steady state''.
==Needed Cooling Power==
The rule of thumb is that 1/3 of the power you put into the engine in the form of fuel flow turns into heat. 1/3 becomes the power that turns the wheels and the last third comes out the exhaust or gets dissipated over the air [citation needed]. This ratio means that the power the radiator has to dissipate is approximately the same as the power sent to the wheels.

You have to keep in mind though that you don't drive full throttle all the time, so you have to average the engine power over the hole stint. You can do that for example by measuring the fuel consumption of your engine. I don't know how accurate that it though, because I've never done it. Also don't mind power peaks, like on a long straight, because the thermal capacity of your coolant is so big that it compensates that easily.[citation needed, just bc yours was big enough, doesnt mean everyone's is]

Finding average power output of the engine is one way to determine necessary cooling power for the engine. This can be accomplished by measuring fuel consumption or engine torque/vehicle velocity (P = FxV).
==Getting that cooling Power==
There are a couple of things that influence how much power the cooling system has:
* Radiator size: This is that you want to get right. It has by far the biggest impact. Radiator size is not created equal as lower temperature water will be cooled less than high temperature water. Therefore, increasing the width of the radiator is more economical with respect to weight than increasing the length. 
* Water flow rate: Basically neglegible. If you switch from a average sized pump to one with twice the flow rate you just get 1 or 2 Watt of additional power. Let's say the air has 30°C and your water 100°C when it enters the radiator and 95°C at the exit of it. Now you swap pumps and the bigger one makes the water leave the radiator at 97°C. You now have increased the temperature difference between the air and water from 67.5K to 68.5K or by 1.5%. This means your cooling power also increased by 1.5%. Measuring water flow rate is invaluable, but it is essential to understand that flow rate depends both on engine RPM and pressure rise imposed by the radiator and the rest of the cooling circuit, as these are generally centrifugal pumps. By contrast, an automotive oil pump is a fixed displacement type that will always deliver a certain oil volumetric flowrate provided it is being fed oil. [citation needed] 
** Not basically negligible, just dimishing returns, if you have 0 water flow rate, you'll get close to 0 cooling no matter what else you do, if you have a properly sized water pump and swap to a bigger one, you'll see limited gains. If the water flow is too low, you won't be able to send enough heat from the engine to the radiator. 
* Airflow: A front wing could make the air go over your radiator and make the engine go boom.
** Also shrouds are said to do stuff.
** Fan - forced convection. Generally, fans are ideally not running during normal operation. Because the margin between running temperature (about 90C) and disaster (100C) is so tight, the fans might have to run fairly aggressively especially on a hot day when chaining autocross laps. A tight seal between fan shroud and the radiator is key to avoid leakage. Spacing between the fan and radiator is also key: you want a uniform pressure difference across the radiator to achieve a uniform flow rate. 
* The angle of the radiator: You can angle it to about 30° (some even say 45°) relative to the airflow without any significant loss in cooling power. [citation needed] 
* single pass v double pass

=Radiator Types=
cross flow / downflow radiator, radiator form factors, and why we all use them
=Radiator Placement=
======Side======
======Rear======
======Multiple======
=System Design=
must be cooled w water only(IC and EV) or oil(EV). 
no additives 
Must be able to pass 45 deg tilt test w no leaks
===Hosing===
type and sizing
===Routing===
keep it short and straight
===Filling and Bleeding===
===Catch Can===
just crush a 1L beer and spray paint the can black, its what we all did, not gonna get any lighter or cheaper.
===Data and Data collection===
see [[:Category:Data Acquisition|Data Acquisition]]

=Other applications=
===Brake cooling===

* Convective
** ducting
** theyre spinning hot disks, they have natural convection
* Radiation

===Oil cooling===
Many engines have an OEM oil/water heat exchanger. From my experience with the 600rr, these are very compact and well integrated with the original powertrain system. Most teams use what is close to the manufacturer's recommended engine oil and the water coolant should be a perfectly fine substitute for the antifreeze solution on the OEM bikes.

why you would want to cool oil
* If it boils or denatures bad things happen - Novotny
* thanks, lol, just a placeholder, isnt meant to be a question, poor phrasing on my end - simon
* all good, I was confused :')

===Intercooler===
===Driver cooling===
lmao

[[Category: Internal Combustion]]

Cooling

2020-06-09T01:27:29Z

RealHumanBean: /* Getting that cooling Power */

More than 50% of energy used in combustion goes into heat[citation needed]. Heat is also generated by the turbulence of the air in the intake and cylinder, as well as friction from the engine's internals. A system is needed to keep the engine within it's operational temperature range.
=Theory=
Cooling systems are designed to dissipate the unwanted thermal energy. Systems are often designed around heat exchangers (HEXs), allowing for efficient exchange of heat from a hot fluid to a cooler one. There are three main methods of heat transfer;
* Conduction: Heat transfer over a temperature differential without motion between the materials
* Convection: Heat transfer over a temperature differential with fluid motion between the materials
* Radiation: Heat transfer due to by energy emitted from the unstable nature of a hot material (shitty definition, but the best I have)
** Heat transfer in the form of electromagnetic radiation emitted by bodies above absolute 0 (wikipedia says its a function of distributing entropy, not sure we're gonna get a simple, and easy answer here)
A heat exchanger (HEX) is normally designed to optimize the heat transfer between two fluids using conduction and convection. The most common HEX is an water to air cooler, meaning it transfers heat between the hot water and the cooler air. These HEXs have a few distinct characteristics, full metal construction, thin metal fins in the streamwise direction, water inlets on top and bottom, with air inlets on the front and back. The metal construction is due to a low conductive heat transfer coefficient within the metal in addition to a low specific heat. These factors allow the metal rapidly conduct heat from the hotter internal water channels to the cooler metal fin tips. Aluminum is nearly universally used in automotive radiators. While materials such as copper may notionally provide more cooling due to higher thermal conductivity, the thermal resistance of aluminum sheet metal is so low that the heat transfer from the water circuit to the air is limited by the convective coefficients. Aluminum also is light and strong as fins or sheets. The fin structure is to maximize convection heat transfer by increasing the surface area the air flows over. The convection heat transfer coefficient is also a function of the airspeed passing the fin, allowing for 'forced convection' where a fan and or vehicle speed is used to impart an inlet speed to the system.Behavior(function?) of radiators vary heavily based upon water channel sizes, fin spacing, and a plethora of other characteristics.
For a more detailed understanding of theory, any heat transfer textbook such as ''Incropera and Dewitt ''will serve. ''Kays and London'''s heat exchanger text is invaluable as a practical reference. It includes heat transfer coefficients for various fin and tube geometries. It is possible to measure the geometry of your radiator's fins, determine what type of fin geometry you are using, and then look up the appropriate set of coefficients for a rather robust heat exchanger model.

=Cooling Power=
The amount of thermal power that the engine puts into the water has to be the same as the thermal power the radiator dissipates ''at steady state''.
==Needed Cooling Power==
The rule of thumb is that 1/3 of the power you put into the engine in the form of fuel flow turns into heat. 1/3 becomes the power that turns the wheels and the last third comes out the exhaust or gets dissipated over the air [citation needed]. This ratio means that the power the radiator has to dissipate is approximately the same as the power sent to the wheels.

You have to keep in mind though that you don't drive full throttle all the time, so you have to average the engine power over the hole stint. You can do that for example by measuring the fuel consumption of your engine. I don't know how accurate that it though, because I've never done it. Also don't mind power peaks, like on a long straight, because the thermal capacity of your coolant is so big that it compensates that easily.[citation needed, just bc yours was big enough, doesnt mean everyone's is]

Finding average power output of the engine is one way to determine necessary cooling power for the engine. This can be accomplished by measuring fuel consumption or engine torque/vehicle velocity (P = FxV).
==Getting that cooling Power==
There are a couple of things that influence how much power the cooling system has:
* Radiator size: This is that you want to get right. It has by far the biggest impact. Radiator size is not created equal as lower temperature water will be cooled less than high temperature water. Therefore, increasing the width of the radiator is more economical with respect to weight than increasing the length. 
* Water flow rate: Basically neglegible. If you switch from a average sized pump to one with twice the flow rate you just get 1 or 2 Watt of additional power. Let's say the air has 30°C and your water 100°C when it enters the radiator and 95°C at the exit of it. Now you swap pumps and the bigger one makes the water leave the radiator at 97°C. You now have increased the temperature difference between the air and water from 67.5K to 68.5K or by 1.5%. This means your cooling power also increased by 1.5%. Measuring water flow rate is invaluable, but it is essential to understand that flow rate depends both on engine RPM and pressure rise imposed by the radiator and the rest of the cooling circuit, as these are generally centrifugal pumps. By contrast, an automotive oil pump is a fixed displacement type that will always deliver a certain oil volumetric flowrate provided it is being fed oil. [citation needed] 
** Not basically negligible, just dimishing returns, if you have 0 water flow rate, you'll get close to 0 cooling no matter what else you do, if you have a properly sized water pump and swap to a bigger one, you'll see limited gains. If the water flow is too low, you won't be able to send enough heat from the engine to the radiator. 
* Airflow: A front wing could make the air go over your radiator and make the engine go boom.
** Also shrouds are said to do stuff.
** Fan - forced convection. Generally, fans are ideally not running during normal operation. Because the margin between running temperature (about 90C) and disaster (100C) is so tight, the fans might have to run fairly aggressively especially on a hot day when chaining autocross laps. A tight seal between fan shroud and the radiator is key to avoid leakage. Spacing between the fan and radiator is also key: you want a uniform pressure difference across the radiator to achieve a uniform flow rate. 
* The angle of the radiator: You can angle it to about 30° (some even say 45°) relative to the airflow without any significant loss in cooling power. [citation needed] 
* single pass v double pass

=Radiator Types=
cross flow / downflow radiator, radiator form factors, and why we all use them
=Radiator Placement=
======Side======
======Rear======
======Multiple======
=System Design=
must be cooled w water only(IC and EV) or oil(EV). 
no additives 
Must be able to pass 45 deg tilt test w no leaks
===Hosing===
type and sizing
===Routing===
keep it short and straight
===Filling and Bleeding===
===Catch Can===
just crush a 1L beer and spray paint the can black, its what we all did, not gonna get any lighter or cheaper.
===Data and Data collection===
see [[:Category:Data Acquisition|Data Acquisition]]

=Other applications=
===Brake cooling===

* Convective
** ducting
** theyre spinning hot disks, they have natural convection
* Radiation

===Oil cooling===
why you would want to cool oil
* If it boils or denatures bad things happen - Novotny
* thanks, lol, just a placeholder, isnt meant to be a question, poor phrasing on my end - simon
* all good, I was confused :')

===Intercooler===
===Driver cooling===
lmao

[[Category: Internal Combustion]]

Cooling

2020-06-09T01:23:22Z

RealHumanBean: /* Getting that cooling Power */

More than 50% of energy used in combustion goes into heat[citation needed]. Heat is also generated by the turbulence of the air in the intake and cylinder, as well as friction from the engine's internals. A system is needed to keep the engine within it's operational temperature range.
=Theory=
Cooling systems are designed to dissipate the unwanted thermal energy. Systems are often designed around heat exchangers (HEXs), allowing for efficient exchange of heat from a hot fluid to a cooler one. There are three main methods of heat transfer;
* Conduction: Heat transfer over a temperature differential without motion between the materials
* Convection: Heat transfer over a temperature differential with fluid motion between the materials
* Radiation: Heat transfer due to by energy emitted from the unstable nature of a hot material (shitty definition, but the best I have)
** Heat transfer in the form of electromagnetic radiation emitted by bodies above absolute 0 (wikipedia says its a function of distributing entropy, not sure we're gonna get a simple, and easy answer here)
A heat exchanger (HEX) is normally designed to optimize the heat transfer between two fluids using conduction and convection. The most common HEX is an water to air cooler, meaning it transfers heat between the hot water and the cooler air. These HEXs have a few distinct characteristics, full metal construction, thin metal fins in the streamwise direction, water inlets on top and bottom, with air inlets on the front and back. The metal construction is due to a low conductive heat transfer coefficient within the metal in addition to a low specific heat. These factors allow the metal rapidly conduct heat from the hotter internal water channels to the cooler metal fin tips. Aluminum is nearly universally used in automotive radiators. While materials such as copper may notionally provide more cooling due to higher thermal conductivity, the thermal resistance of aluminum sheet metal is so low that the heat transfer from the water circuit to the air is limited by the convective coefficients. Aluminum also is light and strong as fins or sheets. The fin structure is to maximize convection heat transfer by increasing the surface area the air flows over. The convection heat transfer coefficient is also a function of the airspeed passing the fin, allowing for 'forced convection' where a fan and or vehicle speed is used to impart an inlet speed to the system.Behavior(function?) of radiators vary heavily based upon water channel sizes, fin spacing, and a plethora of other characteristics.
For a more detailed understanding of theory, any heat transfer textbook such as ''Incropera and Dewitt ''will serve. ''Kays and London'''s heat exchanger text is invaluable as a practical reference. It includes heat transfer coefficients for various fin and tube geometries. It is possible to measure the geometry of your radiator's fins, determine what type of fin geometry you are using, and then look up the appropriate set of coefficients for a rather robust heat exchanger model.

=Cooling Power=
The amount of thermal power that the engine puts into the water has to be the same as the thermal power the radiator dissipates ''at steady state''.
==Needed Cooling Power==
The rule of thumb is that 1/3 of the power you put into the engine in the form of fuel flow turns into heat. 1/3 becomes the power that turns the wheels and the last third comes out the exhaust or gets dissipated over the air [citation needed]. This ratio means that the power the radiator has to dissipate is approximately the same as the power sent to the wheels.

You have to keep in mind though that you don't drive full throttle all the time, so you have to average the engine power over the hole stint. You can do that for example by measuring the fuel consumption of your engine. I don't know how accurate that it though, because I've never done it. Also don't mind power peaks, like on a long straight, because the thermal capacity of your coolant is so big that it compensates that easily.[citation needed, just bc yours was big enough, doesnt mean everyone's is]

Finding average power output of the engine is one way to determine necessary cooling power for the engine. This can be accomplished by measuring fuel consumption or engine torque/vehicle velocity (P = FxV).
==Getting that cooling Power==
There are a couple of things that influence how much power the cooling system has:
* Radiator size: This is that you want to get right. It has by far the biggest impact.
* Water flow rate: Basically neglegtible. If you switch from a average sized pump to one with twice the flow rate you just get 1 or 2 Watt of additional power. Let's say the air has 30°C and your water 100°C when it enters the radiator and 95°C at the exit of it. Now you swap pumps and the bigger one makes the water leave the radiator at 97°C. You now have increased the temperature difference between the air and water from 67.5K to 68.5K or by 1.5%. This means your cooling power also increased by 1.5%. Measuring water flow rate is invaluable, but it is essential to understand that flow rate depends both on engine RPM and pressure rise imposed by the radiator and the rest of the cooling circuit, as these are generally centrifugal pumps. By contrast, an automotive oil pump is a fixed displacement type that will always deliver a certain oil volumetric flowrate provided it is being fed oil. [citation needed] 
** Not basically negligible, just dimishing returns, if you have 0 water flow rate, you'll get close to 0 cooling no matter what else you do, if you have a properly sized water pump and swap to a bigger one, you'll see limited gains. If the water flow is too low, you won't be able to send enough heat from the engine to the radiator. 
* Airflow: A front wing could make the air go over your radiator and make the engine go boom.
** Also shrouds are said to do stuff.
** Fan - forced convection
* The angle of the radiator: You can angle it to about 30° (some even say 45°) relative to the airflow without any significant loss in cooling power. [citation needed] 
* single pass v double pass

=Radiator Types=
cross flow / downflow radiator, radiator form factors, and why we all use them
=Radiator Placement=
======Side======
======Rear======
======Multiple======
=System Design=
must be cooled w water only(IC and EV) or oil(EV). 
no additives 
Must be able to pass 45 deg tilt test w no leaks
===Hosing===
type and sizing
===Routing===
keep it short and straight
===Filling and Bleeding===
===Catch Can===
just crush a 1L beer and spray paint the can black, its what we all did, not gonna get any lighter or cheaper.
===Data and Data collection===
see [[:Category:Data Acquisition|Data Acquisition]]

=Other applications=
===Brake cooling===

* Convective
** ducting
** theyre spinning hot disks, they have natural convection
* Radiation

===Oil cooling===
why you would want to cool oil
* If it boils or denatures bad things happen - Novotny
* thanks, lol, just a placeholder, isnt meant to be a question, poor phrasing on my end - simon
* all good, I was confused :')

===Intercooler===
===Driver cooling===
lmao

[[Category: Internal Combustion]]

Cooling

2020-06-09T01:20:49Z

RealHumanBean: /* Theory */

More than 50% of energy used in combustion goes into heat[citation needed]. Heat is also generated by the turbulence of the air in the intake and cylinder, as well as friction from the engine's internals. A system is needed to keep the engine within it's operational temperature range.
=Theory=
Cooling systems are designed to dissipate the unwanted thermal energy. Systems are often designed around heat exchangers (HEXs), allowing for efficient exchange of heat from a hot fluid to a cooler one. There are three main methods of heat transfer;
* Conduction: Heat transfer over a temperature differential without motion between the materials
* Convection: Heat transfer over a temperature differential with fluid motion between the materials
* Radiation: Heat transfer due to by energy emitted from the unstable nature of a hot material (shitty definition, but the best I have)
** Heat transfer in the form of electromagnetic radiation emitted by bodies above absolute 0 (wikipedia says its a function of distributing entropy, not sure we're gonna get a simple, and easy answer here)
A heat exchanger (HEX) is normally designed to optimize the heat transfer between two fluids using conduction and convection. The most common HEX is an water to air cooler, meaning it transfers heat between the hot water and the cooler air. These HEXs have a few distinct characteristics, full metal construction, thin metal fins in the streamwise direction, water inlets on top and bottom, with air inlets on the front and back. The metal construction is due to a low conductive heat transfer coefficient within the metal in addition to a low specific heat. These factors allow the metal rapidly conduct heat from the hotter internal water channels to the cooler metal fin tips. Aluminum is nearly universally used in automotive radiators. While materials such as copper may notionally provide more cooling due to higher thermal conductivity, the thermal resistance of aluminum sheet metal is so low that the heat transfer from the water circuit to the air is limited by the convective coefficients. Aluminum also is light and strong as fins or sheets. The fin structure is to maximize convection heat transfer by increasing the surface area the air flows over. The convection heat transfer coefficient is also a function of the airspeed passing the fin, allowing for 'forced convection' where a fan and or vehicle speed is used to impart an inlet speed to the system.Behavior(function?) of radiators vary heavily based upon water channel sizes, fin spacing, and a plethora of other characteristics.
For a more detailed understanding of theory, any heat transfer textbook such as ''Incropera and Dewitt ''will serve. ''Kays and London'''s heat exchanger text is invaluable as a practical reference. It includes heat transfer coefficients for various fin and tube geometries. It is possible to measure the geometry of your radiator's fins, determine what type of fin geometry you are using, and then look up the appropriate set of coefficients for a rather robust heat exchanger model.

=Cooling Power=
The amount of thermal power that the engine puts into the water has to be the same as the thermal power the radiator dissipates ''at steady state''.
==Needed Cooling Power==
The rule of thumb is that 1/3 of the power you put into the engine in the form of fuel flow turns into heat. 1/3 becomes the power that turns the wheels and the last third comes out the exhaust or gets dissipated over the air [citation needed]. This ratio means that the power the radiator has to dissipate is approximately the same as the power sent to the wheels.

You have to keep in mind though that you don't drive full throttle all the time, so you have to average the engine power over the hole stint. You can do that for example by measuring the fuel consumption of your engine. I don't know how accurate that it though, because I've never done it. Also don't mind power peaks, like on a long straight, because the thermal capacity of your coolant is so big that it compensates that easily.[citation needed, just bc yours was big enough, doesnt mean everyone's is]

Finding average power output of the engine is one way to determine necessary cooling power for the engine. This can be accomplished by measuring fuel consumption or engine torque/vehicle velocity (P = FxV).
==Getting that cooling Power==
There are a couple of things that influence how much power the cooling system has:
* Radiator size: This is that you want to get right. It has by far the biggest impact.
* Water flow rate: Basically neglegtible. If you switch from a average sized pump to one with twice the flow rate you just get 1 or 2 Watt of additional power. Let's say the air has 30°C and your water 100°C when it enters the radiator and 95°C at the exit of it. Now you swap pumps and the bigger one makes the water leave the radiator at 97°C. You now have increased the temperature difference between the air and water from 67.5K to 68.5K or by 1.5%. This means your cooling power also increased by 1.5%. [citation needed] 
** Not basically negligible, just dimishing returns, if you have 0 water flow rate, you'll get close to 0 cooling no matter what else you do, if you have a properly sized water pump and swap to a bigger one, you'll see limited gains. If the water flow is too low, you won't be able to send enough heat from the engine to the radiator. 
* Airflow: A front wing could make the air go over your radiator and make the engine go boom.
** Also shrouds are said to do stuff.
** Fan - forced convection
* The angle of the radiator: You can angle it to about 30° (some even say 45°) relative to the airflow without any significant loss in cooling power. [citation needed] 
* single pass v double pass

=Radiator Types=
cross flow / downflow radiator, radiator form factors, and why we all use them
=Radiator Placement=
======Side======
======Rear======
======Multiple======
=System Design=
must be cooled w water only(IC and EV) or oil(EV). 
no additives 
Must be able to pass 45 deg tilt test w no leaks
===Hosing===
type and sizing
===Routing===
keep it short and straight
===Filling and Bleeding===
===Catch Can===
just crush a 1L beer and spray paint the can black, its what we all did, not gonna get any lighter or cheaper.
===Data and Data collection===
see [[:Category:Data Acquisition|Data Acquisition]]

=Other applications=
===Brake cooling===

* Convective
** ducting
** theyre spinning hot disks, they have natural convection
* Radiation

===Oil cooling===
why you would want to cool oil
* If it boils or denatures bad things happen - Novotny
* thanks, lol, just a placeholder, isnt meant to be a question, poor phrasing on my end - simon
* all good, I was confused :')

===Intercooler===
===Driver cooling===
lmao

[[Category: Internal Combustion]]

Cooling

2020-06-09T01:16:58Z

RealHumanBean: /* Theory */

More than 50% of energy used in combustion goes into heat[citation needed]. Heat is also generated by the turbulence of the air in the intake and cylinder, as well as friction from the engine's internals. A system is needed to keep the engine within it's operational temperature range.
=Theory=
Cooling systems are designed to dissipate the unwanted thermal energy. Systems are often designed around heat exchangers (HEXs), allowing for efficient exchange of heat from a hot fluid to a cooler one. There are three main methods of heat transfer;
* Conduction: Heat transfer over a temperature differential without motion between the materials
* Convection: Heat transfer over a temperature differential with fluid motion between the materials
* Radiation: Heat transfer due to by energy emitted from the unstable nature of a hot material (shitty definition, but the best I have)
** Heat transfer in the form of electromagnetic radiation emitted by bodies above absolute 0 (wikipedia says its a function of distributing entropy, not sure we're gonna get a simple, and easy answer here)
A heat exchanger (HEX) is normally designed to optimize the heat transfer between two fluids using conduction and convection. The most common HEX is an water to air cooler, meaning it transfers heat between the hot water and the cooler air. These HEXs have a few distinct characteristics, full metal construction, thin metal fins in the streamwise direction, water inlets on top and bottom, with air inlets on the front and back. The metal construction is due to a low conductive heat transfer coefficient within the metal in addition to a low specific heat. These factors allow the metal rapidly conduct heat from the hotter internal water channels to the cooler metal fin tips. Aluminum is nearly universally used in automotive radiators. While materials such as copper may notionally provide more cooling due to higher thermal conductivity, the thermal resistance of aluminum sheet metal is so low that the heat transfer from the water circuit to the air is limited by the convective coefficients. Aluminum also is light and strong as fins or sheets. The fin structure is to maximize convection heat transfer by increasing the surface area the air flows over. The convection heat transfer coefficient is also a function of the airspeed passing the fin, allowing for 'forced convection' where a fan and or vehicle speed is used to impart an inlet speed to the system.Behavior(function?) of radiators vary heavily based upon water channel sizes, fin spacing, and a plethora of other characteristics.

=Cooling Power=
The amount of thermal power that the engine puts into the water has to be the same as the thermal power the radiator dissipates ''at steady state''.
==Needed Cooling Power==
The rule of thumb is that 1/3 of the power you put into the engine in the form of fuel flow turns into heat. 1/3 becomes the power that turns the wheels and the last third comes out the exhaust or gets dissipated over the air [citation needed]. This ratio means that the power the radiator has to dissipate is approximately the same as the power sent to the wheels.

You have to keep in mind though that you don't drive full throttle all the time, so you have to average the engine power over the hole stint. You can do that for example by measuring the fuel consumption of your engine. I don't know how accurate that it though, because I've never done it. Also don't mind power peaks, like on a long straight, because the thermal capacity of your coolant is so big that it compensates that easily.[citation needed, just bc yours was big enough, doesnt mean everyone's is]

Finding average power output of the engine is one way to determine necessary cooling power for the engine. This can be accomplished by measuring fuel consumption or engine torque/vehicle velocity (P = FxV).
==Getting that cooling Power==
There are a couple of things that influence how much power the cooling system has:
* Radiator size: This is that you want to get right. It has by far the biggest impact.
* Water flow rate: Basically neglegtible. If you switch from a average sized pump to one with twice the flow rate you just get 1 or 2 Watt of additional power. Let's say the air has 30°C and your water 100°C when it enters the radiator and 95°C at the exit of it. Now you swap pumps and the bigger one makes the water leave the radiator at 97°C. You now have increased the temperature difference between the air and water from 67.5K to 68.5K or by 1.5%. This means your cooling power also increased by 1.5%. [citation needed] 
** Not basically negligible, just dimishing returns, if you have 0 water flow rate, you'll get close to 0 cooling no matter what else you do, if you have a properly sized water pump and swap to a bigger one, you'll see limited gains. If the water flow is too low, you won't be able to send enough heat from the engine to the radiator. 
* Airflow: A front wing could make the air go over your radiator and make the engine go boom.
** Also shrouds are said to do stuff.
** Fan - forced convection
* The angle of the radiator: You can angle it to about 30° (some even say 45°) relative to the airflow without any significant loss in cooling power. [citation needed] 
* single pass v double pass

=Radiator Types=
cross flow / downflow radiator, radiator form factors, and why we all use them
=Radiator Placement=
======Side======
======Rear======
======Multiple======
=System Design=
must be cooled w water only(IC and EV) or oil(EV). 
no additives 
Must be able to pass 45 deg tilt test w no leaks
===Hosing===
type and sizing
===Routing===
keep it short and straight
===Filling and Bleeding===
===Catch Can===
just crush a 1L beer and spray paint the can black, its what we all did, not gonna get any lighter or cheaper.
===Data and Data collection===
see [[:Category:Data Acquisition|Data Acquisition]]

=Other applications=
===Brake cooling===

* Convective
** ducting
** theyre spinning hot disks, they have natural convection
* Radiation

===Oil cooling===
why you would want to cool oil
* If it boils or denatures bad things happen - Novotny
* thanks, lol, just a placeholder, isnt meant to be a question, poor phrasing on my end - simon
* all good, I was confused :')

===Intercooler===
===Driver cooling===
lmao

[[Category: Internal Combustion]]