Louvered wheel wells on race cars

[Tango Charlie]

I'm talking about the row of louvers on the top of the front fenders, right ahead of the side view mirrors.
What's their purpose? Are they for something boring and non-ecomodder applicable like brake cooling, or are they evacuating the wheel well to eliminate aerodynamic drag at the front wheel arch? Or something else?

[FastPlastic]

I'm no genius when it comes to aerodynamics but to me it looks like their trying to pull air out the top of the wheel well (trying to keep it from going under?). although the top one seems like a weird place to jet it (right at the mirrors?).

[Daox]

That would probably be done for brake cooling.

[cfg83]

Tango Charlie -

Jackpot! I googled "racing wheel louvers" and got this :

AUTO-RACING - NASCAR Racing Schedule - F1 - Formula 1 - Drag Racing - Motorsports - Indy Car - SPEEDtv.com

... Louvers are used over the fenders of sportscars to relive high pressure that builds up from the fast spinning tire, and from the complex interaction of air flowing in, out, and through the wheel arch.

The general rule is the more air you can extract from the wheel well, the better. On street courses, prototype teams will usually sport the biggest, longest, and most aggressive forms of louvers to vent air and create downforce. Another aspect of most louvers is their taller height (to give air a ‘chimney’ to flow out from) – that extra height adds more volume to the outer profile of the car—making a bigger hole for the passing air to go over and thus reducing straightline speed. ...

Read the article for more details.

CarloSW2

[Tango Charlie]

Awesome link, cfg83!
That definitely answers my questions.
Now I'm wondering how to implement it on my Vibe...

[cfg83]

Tango Charlie -

Originally Posted by Tango Charlie

Awesome link, cfg83!
That definitely answers my questions.
Now I'm wondering how to implement it on my Vibe...

Yeah, from the description in the article, it seems like it would be easier to implement on a Chrysler PT Cruiser or an old/new Beetle. On modern car designs like ours that have flush wheel-wells, it's hard to figure out where to put the louvers.

CarloSW2

[OfficeLinebacker]

Great thread.

Well don't most cars have plastic fender liners/wheel wells? Seems easy enough to cut slots in those! (Then again, where does the air go after that?)

I've often thought that the climate control system has great potential to assist with aero. Perhaps some kind of ducting could be rigged up so that the fan pulls air from the wheel wells?

[aerohead]

Remember,these are race cars! Their windshields are inside the wake area of the fender-top extractors.In inclement weather,there will be quite a rooster-tail of rain water exploding out the top of those fenders.If it doesn't destroy your vision,it may not be the same for those following in traffic.Also,you may completely destroy the airflow in that area.GTP cars can have drag coefficients like Cd 0.7!!!!!!!!! They're way cool at the track,and they need a lot of brake cooling coming off a straightaway into the first curve.Not the sort of thing we'll be doing on daily commutes.

[lunarhighway]

i believe something similar, useing an inverse scoop like setup was first used on a 70's muscle car... can't come up with the name though.

one thing that puzzles me is that this seems to sugest rheres high pressure in the wheelwells, while other sources sugest there's a low pressure...

i could accept eihter case, but i'm running a bellypan i'm somewhat relying on the "low pressure theory" for radiator air extraction.

or is this the reason these sports cars use this setup as well?

[Tango Charlie]

Thanks, aerohead. I hadn't thought of the rain aspect. That would be a sight to see!

Racecars are so beguiling. They look so sleek and sexy, yet so many of their features don't translate to FE on our daily drivers.
But
What if we (somehow) ran a duct from the inner wheel well back to the rear of the car into a low pressure area...
The size of duct to make a difference would probably make it not feasible.