Quote:
Originally Posted by jamesqf
Something I've wondered about is whether the heated air could be exhausted at strategic locations in order to reduce drag. It seems you'd have a mild ramjet effect, since the air going through the radiator is heated, and so expands. Some of the diagrams seem to be taking advantage of this, but is there anything more explicit?
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Yes, and although it doesn't look like it in the diagram that's exactly what setups B and C are attempting to do. In diagram B, it's showing the ducted expansion air exhausting around the front tires which can disrupt the turbulence that exists without a wheel skirt.
In setup C the idea is to take high pressure air from in front of the air dam, duct it through the radiator, and duct the warmed air out through hood-top vents into the low pressure area that typically develops above a car's hood. In a lot of racing applications the nose is blunt with a flat hood (stock cars, touring cars, side pods on open wheel) rather like a lot of production vehicles. This generates a low-pressure zone on top of the hood and causes frontal lift. Extending front air dams and installing chin splitters helps counter act this by reducing air flow underneath the car, but as shown in diagram C ducting the stall pressure air from the nose through the cooling system and injecting it into the low pressure zone will equalize the pressure. I'm convinced this is the most effective method. I've seen it work in a small-scale open wheel bike-engined car where designs A and D had caused repeated overheating issues, a switch to design C in a side pod with a smaller radiator produced reliable driving for hours on end. Granted this was in a vehicle that never saw above 50mph for more than 2-3 seconds so aero was not much of a factor the cooling performance worked very well.