Race car aerodynamics frontal area outlets

[Gracer22]

Hi Guys,


First time poster so go easy....

In the following pics i have highlighted some frontal radiator exhaust areas in red.

http://img826.imageshack.us/g/dscf2527.jpg/

My question is why have they created outlets like this? What would their use be? What pressures etc would you expect to see?

As i understand it the air would enter the front go through the radiator then exit through the outlets. I'm assuming due to high pressure air one side and low pressure air at the outlet side this would assist in cooling the radiator but what affect would this cause at the outlet aerodynamically?

Would it help with wheel turbulence? Less drag? Could it be detrimental to cars performance?

Im an aero noob but an electrical engineer so feel free to get technical.

Cheers guys

 

[rb1957]

ok, i'm not a "gear-head" but here's my take ... race cars pretty much seal the bottom of the car (to control airflow underneath the car), so you can't exhaust the rad into the engine bay (adding the hot exhaust into a closed volume with a large heat source doesn't sound like a good idea) ... you're not going to duct the exhaust to the back of the car, so out the sides. i'm also guessing (like you) that there is a beneficial pressure gradient (low pressure behind the bow-wave at the front of the car).

my 2c ... probably not worth that ...

 

[swearingen]

You're exactly right, rb - there is a local low behind the initial high of the bow wave that will help evacuate the cooling air. Also, there is a local low near the tops of the fenders which is why you see many vents there as well.


-5^2 = -25 ;-)

http://www.eng-tips.com/supportus.cfm

 

[SAITAETGrad]

It likely can help with cleaning up the aerodynamics of the wheel. On WWII fighters, the radiator cooling was vented to areas of disturbed air to clean up the aerodynamics and even provide a signifcant amount of thurst. In some motorcycles with ducted radiators, the exaust is placed at or behind the rear wheel to help the aerodynamics. I would imagine that these cars would not get as much benefit as a WWII fighter or a race bike- but don't know much.

 

[isaacowen]

can anyone comment if their is a difference between say venting out the side as per this pic and venting up over bonnet/hood r.e gt40 and some other racers? does it add downforce at the rear wing passing this "extra"air over the roof?

 

[IRstuff]

The pressure differential is probably tiny, at best, which means the airflow is tine, at best.

If you want airflow over the spoiler, then don't run it through the body. All the extra resistance from the ducting lowers the pressure and the flow.

TTFN

FAQ731-376

 

[isaacowen]

thankyou. figured as much.

 

[tbuelna]

Gracer22,

The discharged airflow exiting those radiator ducts has high velocity/momentum due to the large amounts of energy imparted to it as it passes across the heat exchanger core. The cars shown in your pictures are likely flat bottom cars. Discharging the high velocity cooling airflow along the side edge gaps of the car's flat bottom creates a local low pressure zone that extracts air out from underneath the flat chassis bottom, creating downforce.

As a mechanical guy, with no aero knowledge, that's my explanation for it. So take it for what it's worth!

Good luck.
Terry