My 1 cent :
[QUOTE=a8ksh4;163383]Random late night idea: Would it make any sense to use turbines to extract power from air just before it goes turbulent at the back of a vehicle?
Several years ago ( around 1999 ), Popular Mechanics had a tiny snippet of information on a company that had modified a van with a fan mounted on the roof. The fan was mounted on its' side and the blades would twist in such a way that they would become flat as they reached a certain point, reducing drag.
As the vehicle would drive forward, the blades would turn in the wind charging the battery ( this was an EV concept. )
Like so much that PM prints, it was apparently all empty promises.
Not sure if that was any use at all, since that doesn't answer your question.
How about running a fan (or an array of fans) gyro-copter-style just behind the detachment point to force air into the low pressure area behind the car? Could something like this be used in such a way as to smooth out the flow behind the car enough to justify the energy spent spinning up the blades?
Check out my thread on Coanda slots. There has been some research done on using high pressure air to blast the wake into a more ideal shape.
http://ecomodder.com/forum/showthrea...ots-10972.html