Thread: Vents
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Old 07-13-2019, 12:30 PM   #61 (permalink)
aerohead
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ideal

Quote:
Originally Posted by Taylor95 View Post
Can you elaborate on what an ideal cooling system is?

I'm thinking about putting vents in the wheel wells too. This would improve airflow through the engine bay in addition to keeping my brakes cooler at lower speeds.
I think that venting the wheel wells might improve mpg slightly at highway speeds because my wheel wells are a high pressure area.
At the time Hucho wrote the second edition of his aerodynamic textbook in the late-1980s,the typical passenger car's cooling systems drag contribution was around 12% of the car's overall drag.
With a cooling system,like freebeard has shared,the drag portion is reduced to 2% of the overall drag.
And as freebeard also shared,on a land speed record streamliner at Bonneville,at transonic speed,you could take advantage of that Merideth effect,where the heat flux coming off the engine expands the air against compressed-ram-air,actually providing net thrust.
The trick with the extractor side of the equation,is expelling the air in such a way that it merges with the external body flow field at an identical velocity,and parallel to the body.A look at the 1978 Pininfarina CNR,'banana' car will illustrate such a setup.It took about $100,000 in wind tunnel time to 'tune' these vents for the lowest drag.

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