Bob C
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| posted on 19/10/05 at 12:31 PM |
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Can anyone help with aerodynamics modelling?
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
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I love speed :-P
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| posted on 19/10/05 at 01:00 PM |
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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
Don't Steal
The Government doesn’t like the competition
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jambojeef
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| posted on 19/10/05 at 01:07 PM |
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Was this the Greenpower competition?
We're entered for that too
Geoff
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Bob C
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| posted on 19/10/05 at 01:41 PM |
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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
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mattpilmoor
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| posted on 19/10/05 at 04:24 PM |
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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]
Measure twice - Cut once - Still f*!K it up!
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Bob C
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| posted on 19/10/05 at 11:05 PM |
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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
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mattpilmoor
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| posted on 20/10/05 at 07:18 AM |
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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
Measure twice - Cut once - Still f*!K it up!
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