Quote:
freebeard:
--> Nowadays, I am studying the effects of placing exhaust above the diffuser on my team's car, trying to pull air under the car to get the diffuser to 'up to speed' faster, since underbodies can become effective at as low as 20 mph under normal conditions (our average speed in the Formula SAE competition is around 30-40 mph, so it's vital we make as much use of these things as possible).
--> It wouldn't be negative pressure, just less pressure (probably).
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--> Who knows where, but I'm convinced I saved a magazine article about a Porsche racing special that had something about as big as a large muffler behind each rear wheel that had an exhaust tip in the middle of a venturi. Sort of like a high-bypass turbo-jet. Free engine cooling.
I'll have to admit that my conception of a 'diffuser' would be a ramp-bed truck bed with multiple tailfins, upside down. So when you say, "exhaust above the diffuser", I picture it exhausting at the termination of the ramp. How far wrong is that?
--> So, less turbulence, right?
Quote:
aerohead:
--> Dimpling a surface changes up Reynold's numbers. Size matters, but so does everything else.
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In another life I had a consuming interest in low-cost, energy efficient and aerodynamic housing. It occurs to me that it the geodesic dome has a frequency that is independent of the physical size. There should be a change in Reynolds number over the range between the icosahedron and might-as-well-be sphere.
I don't know that anyone has published these numbers. This would be relevant when I get to my plan to Template a class-A motorhome.