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Old 08-29-2014, 12:38 PM   #1 (permalink)
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Is the windshield base suitable as a radiator air exit?

I remember that the windshield base is a high pressure zone thus better to place an air inlet instead of an outlet.

However in Joseph Katz book Race Car Aerodynamics Designing for Speed it advises to put the radiator air outlets both behind the front wheels and in the windshield base in a prototype car.
Why is that?


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Old 08-29-2014, 12:52 PM   #2 (permalink)
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It's hard to say from the pic exactly what the angles are, but on most vehicles the high pressure at the base of the windshield is because the windshield stands up at a steeper angle than the hood. On the prototype, it looks like there should be little difference between the angles of the hood and windshield, eliminating the high pressure zone normally found there
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Old 08-29-2014, 12:55 PM   #3 (permalink)
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When I was researching my radiator hood ducting ideas (http://ecomodder.com/forum/showthrea...one-29689.html), I found similar designs and write ups. Best I could tell, they only work when designed to work. The average car will simply suck in air (cowl induction). I think part of it has to do with ducting that forces the air out by matching exterior speed/pressure, and another big part of it is the aerodynamic design of the hood/windshield for the optimization of the pressure differentials. But that's just speculation on my part.

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Old 08-29-2014, 05:56 PM   #4 (permalink)
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I believe so. I have a few washers under the hood hinges to raise the rear of my hood to help suck air out from under it and clear the windshield of frost and dew.

I also have to use inside air as thats where the HVAC sucks in air from the outside.
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Old 08-29-2014, 06:29 PM   #5 (permalink)
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why

Quote:
Originally Posted by Big time View Post
I remember that the windshield base is a high pressure zone thus better to place an air inlet instead of an outlet.

However in Joseph Katz book Race Car Aerodynamics Designing for Speed it advises to put the radiator air outlets both behind the front wheels and in the windshield base in a prototype car.
Why is that?

The technology dates to the 1930s,with Dr.Kamm,who used the cooling system flow to energize the flow going over the windscreen,which otherwise would be stalling.The injection of kinetic energy into the boundary layer allowed for attached flow where otherwise there'd be separation.
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Old 08-30-2014, 03:39 PM   #6 (permalink)
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I did an interesting intercooler mod with my old Toyota Soarer drift car, ducted via grill & venting via the front of the bonnet (known as a V-mount system) Using the negative air pressure over the bonnet to suck through the cooling air. tuff testing suggested it worked rather well.

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Old 09-04-2014, 03:06 PM   #7 (permalink)
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It also depends on the pressure differential between the engine bay under hood, and the external cowl area. If HIGHER pressure is found under hood, then it would work, and likely reduce front drag and lift. Thinking about the wind tunnel smoke vids I've seen, most cowl areas appear to be pretty clean, as though there isn't a substantial pressure increase at the cowl. Testing needed! Interested to hear others thoughts on this

Edit: I bet having a grille block off would make it less likely to work due to less pressure under hood

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