Quote:
Originally Posted by tortoise
A grill block giving the same reduction of internal flow as the turbine will reduce power required more than the turbine would have produced. Unless the turbine is greater than 100% efficient. Give up on this one.
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If the drag reduction is due to reduction of internal flow then any form of blockage inside the internal flow intake that reduces the flow the same amount will reduce the drag the same amount. The case is we have a required mass of air that must flow internally to cool the engine. The dynamic pressure of the air is not needed for the cooling. So if we convert some of that dynamic pressure into energy we are not preventing it from cooling the engine. Turbine efficiency never enters the equation. The argument that since your generating something its going to create more drag due to thermodynamics doesn't apply here. Your just utilizing a resource more effectively.
If you don't buy that in the 80's nasa put wing tip turbines on a piper aircraft and showed you could generate electricity while reducing drag.