turbof1 wrote:Why wouldn't you point the exhaust directly into the diffuser? Coanda really was only a way to circumvent the rules. Hell, even exhaust blown diffusers are a reaction to diffuser ruling. Increase diffuser size and extend the sidewalls low enough to the ground gives the same effect.
Personally I'd discourage using exhaust gasses to get more downforce on a road car. Grip would become partly throttle dependent. Loosing grip in the middle of traffic isn't exactly healthy. You could try applying off-throttle maps, but know that fuel consumptions goes up by quite alot on a machine which you can't describe as "economical" already.
Agreed. For my retirement project (still on paper) I have toyed with this same idea myself, and come to the same conclusion.
However, I do not believe that all of the energy of the exhaust needs to be wasted. In my layman's understanding of the aerodynamics involved, if more energy can be put into the constriction ahead of the diffuser then the air in this region will move faster creating more downforce. My solution would be to build catalytic converters with smooth conductive bottoms, and reflective and insulated tops. Then placement of the converters as forward as reasonable will allow some of the heat energy from the catalytic converters to enter the Venturi. While there may still be some throttle dependency, the metal heat sink of the catalytic converter is likely to reduce said variation.
Now I am still a bit confused about the actual diffuser. I have read the explanations in this forum and elsewhere, and watched the YouTube videos. I understand it for about two seconds, and then I am confused again. The pressure in the diffuser area is high, but the volume of air leaving the constriction is expanding. This expansion is what helps draw out more air from the constriction creating more downforce. Therefore if the diffuser is bigger, more downforce is created.
So in my system, as the exhaust tubes work their way toward the rear of the car, would I want them to also be flat bottomed and conductive, or would i want them to be insulated. In other words, would I want to introduce heat into the diffuser area? Or not?
Heat applied to a gas usually means expansion, which sounds desirable, but would the same heat create a back pressure on the constriction?
