I help out with a school electric car race team. We were outclassed in the final at the weekend & it's clear to get on the pace we need a drag coefficient near the magic 0.1.
Can anyone help by modelling our aerodynamics?
Cheers
Bob

so how did it go at goodwood?, cus our driver crashed on the 1st lap and put us out of the race


p.s. i have some wind tunnel software at home which will accpet s"STL" files

Was this the Greenpower competition?

We're entered for that too

Geoff

Yeah I help the Sandbach High girls school team - tough break with the F35 car Mr. Ilovespeed, but the windtunnell software might be interesting & You're local too - hmm I see an evening with a pint & a laptop coming on. . .
I want to compare our car with the best of the rest (turbo tortoise!) & decide between options for progress.
We have the speed, but aero losses alone go over our power budget at 40mph+
Cheers
Bob

Hi Bob,

I'm just finishing a PhD in Aero Engineering! I'd be very - very wary of computational drag results for various reasons.

Do you need low drag/down force or just low drag?

Can you post a picture. I might be able to give you some pointers.

Matt


[Just had a quick search on the internet - I could almost certainly get you some free wind tunnel time near Manchester]

[Edited on 19/10/05 by mattpilmoor]

Cheers Matt,
we just need low drag. I thought s/w could handle comparisons, no? Free wind tunnel time . . . NOW you're talking! Sounds highly educational too!!!
Here's a link to 'the car to beat' & I'm not convinced we're going to improve on it - maybe a torpedo off the deck with faired wheels? I hate the thought of doing another just like it....
http://www.portaprompt.co.uk/greenpower/
cheers
Bob

Software is ok-ish for parametric analysis, if you were looking at down-force/lift then I’d say use it with caution. But drag's a nightmare to predict computationally. Even with high end CFD the mesh parameters and boundary layer turbulence models have to be spot on.

There are much easier and more effective ways of reducing the drag of your car!

1. Start with a low drag body shape (i.e. an aerodynamic body of revolution - a low drag symmetrical aerofoil revolved around an axis. I can help with this.

2. Adjust the body shape as little as possible to just fit around the internal mechanisms of your vehicle.

3. Build a scale model - and measure the drag.

4. If the drag's acceptable (better than portaprompt!) build the vehicle, attach nothing to the external shape - polish and wax to prevent turbulating the boudary layer and then re-test at full scale in the tunnel on a rolling road for accurate info on drag.

The interesting bit - and where I’d expect the most gains are to be had is the design of the underside of the vehicle, the interaction of the air between vehicle with the moving road!

I think you probably could improve on the portapoint car but only marginally. I'll have a chat with some people today and see what i can sort out for you here.

Do you have a CAD model of your vehicle?

Matt