Aero HP equation

[element94]

Hello all,

What is the equation for aero horsepower? I'm trying to calculate the required aero hp to move a hood scoop on a race car. I'm using CFD but the drag force numbers I'm getting are wacky. I'm using Floworks, apply a surface goal to the scoop, apply an equation goal calculating the Cd using the force but the results are everywhere. Any ideas? Thanks.

 

[CESSNA1]

ELEMENT94: The basic equation is

drag force = (0.5)*(p)*(V^2)*A/32.174

p = air density (#/in^3)
V = Velocity (ft/sec)
A = frontal area (in^2)

Make sure the units are consistent

Once you have the force then mmultiplly by veleicty to get the power and divide by 550 to get horsepower.

Drag coefficients are tytpically determined experimentally.
Do not forget the interface between the hood and the scoop, there is also an effect there.

Good luck
Dave

 

[edmacs]

Element94,

You can estimated the drag accretion due to scoops using ESDU and NACA papers. First of all, you need to evaluate the system pressure and flow requirements.

Flush inlets should be used to minimize drag. Scoop inlets are more suitable for systems with high pressure drop.

These papers have empirical equations based on experimental evaluations.

Good Luck,
Edmar