Restrictor - Revision history

SpookySimon: /* Component Design */ outline update

2023-02-20T15:41:16Z

Component Design: outline update

SpookySimon: /* Component Design */ updating outline

2023-02-20T15:27:54Z

Component Design: updating outline

SpookySimon: /* Component Design */ updating outline

2023-02-20T15:24:47Z

Component Design: updating outline

SpookySimon: /* Component Design */

2023-02-20T15:22:35Z

Component Design

SpookySimon: /* Component Design */ outline

2023-02-20T15:09:54Z

Component Design: outline

SpookySimon: /* Factors to Consider */ moving image to right instead of inline

2023-01-26T16:09:41Z

Factors to Consider: moving image to right instead of inline

SpookySimon: adding system design section with bullets

2023-01-26T16:08:25Z

adding system design section with bullets

SpookySimon: more info all over page

2023-01-25T18:36:22Z

more info all over page

SpookySimon: disclaimer

2023-01-25T18:31:41Z

disclaimer

SpookySimon: link to intake,engine

2023-01-10T17:21:16Z

link to intake,engine

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 * Venturi style
 <!-- Air Flow Optimization via a Venturi Type Air Restrictor Anshul Singhal, Mallika Parveen, Member, IAENG -->
 ** Converging angle
 ** Diverging angle

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 ** Converging angle
 ** Diverging angle
-* Bell Nozzle
+* Alternative designs
 * Surface roughness
 ** Boundary layer adhesion

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 =Component Design=
 * Venturi style
 ** Converging angle
 ** Diverging angle

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 =Component Design=
-* Diffusion angle
+* Venturi style
-** intake angle
+** Converging angle
-** output angle
+** Diverging angle
 * Surface roughness
 ** Boundary layer adhesion

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 =Component Design=
 * Diffusion angle
 * Surface roughness
 * Length
 * Material
 * Support
 =References=

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 ==Factors to Consider==
 * What is the effect of the pulsed nature of engine air flow? Is the impact of the pulsed flow consistent throughout the engine's operating range?
 * what is your actual volumetric efficiency?
 * are you operating at Mach # = 1 at all points in the race?
 * what is your restrictor's discharge coefficient?
 ** well designed venturi style restrictors can see Kd as high as 0.95 [citation needed]
 * is your engine operating at 33% efficiency? that is a rough rule of thumb
 =Component Design=

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 |}
 <br />
-Plugging these into the equation above yields a steady state mass flow rate of 0.074 kg air per second for a 20mm restrictor<ref>If you are not using the NASA calculator, use wolfram alpha and include units. There's some weird unit conversion that takes place that will give incorrect results if you just don't use them</ref>. A 19mm hole allows 0.067 kg/s of air.
+Plugging these into the equation above yields a steady state mass flow rate of 0.074 kg air per second for a 20mm restrictor<ref>If you are not using the NASA calculator, use wolfram alpha and include units. There's some weird unit conversion that takes place that will give incorrect results if you just don't use them</ref>. A 19mm hole allows 0.067 kg/s of air. Some ball park power limits can be found as follows:
-<br/>
-<br/>
-Some ball park power limits can be found as follows:
+'''Gasoline'''<br>
 If we assume an AFR of 13.1 (typical lambda for high torque for NA engines[citation needed]), and a Q<sub>LHV</sub> of 43.4 MJ/kg <ref>https://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html</ref> , the mass air flow yields a power limit of 245.1 kW or 328 hp total energy output. If the thermal efficiency of the engine is assumed to be a nominal 33%, the maximum available mechanical power is 81.7 kW or 109 horsepower with 100% volumetric efficiency.
-<br/>
-<br/>
+'''E85'''<br>
 Using an AFR of 8.7 for E85 <ref>https://ftyracing.com/tech/lambda-afr-table/</ref> and a Q<sub>LHV</sub> of 29.2 (citation needed, this was just .85*qlhv ethanol + 0.15 * qlhv gasoline), the limit is 248 kW or 332 hp. The available mechanical power assuming the same efficiency as above is 75.0 kW or 98.5 hp. There are more complexities to using e85 such as the cryogenic effect of fuel vaporization leading to a denser charge, but that is out of the scope for this specific ballpark calculation
 <br/>
 <br/>
 This limit could be exceeded by increasing the upstream pressure to greater than 1 atmosphere. In FSAE, any compressor must be placed after the restrictor so this is not possible.
 ==Factors to Consider==

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 The '''restrictor''' is a part of the [[Intake|intake]] that provides a ceiling for power of the student vehicles in the competition. The theoretical upper limits of the [[Engine|engine's]] power can be derived to be in the ballpark of 100-110hp depending on many factors.
 =Power Limit Derivation=
 The upper limit is derived using the general [https://www.grc.nasa.gov/WWW/K-12/airplane/mflchk.html equation] for ideal compressible gas flow: