Quote:
Originally Posted by Piwoslaw
I found this in Piechna's book. It's based on Kohri and Numata's paper[1].
As can be seen, a diffuser hurts aerodynamic drag in vehicles with a square rear (vans, station wagons). It's something about the diffuser causing eddies that cancel with countereddies from the sloped rear end. In the square rear there are no countereddies, so there is no cancellation.
[1] Kohri I., Numata N., Effects of rear end configuration of vehicles on aerodynamic drag, JSAE Review, December 1985. |
I was looking at this thread again to determine which angle to use for the rear pan/diffuser and this picture really confused me. Is the graph at the bottom showing drag or lift?
Piwoslaw is saying drag, but the numbers on the left correspond to the lift graph in the other diagram. Could one of you who really understand this please explain. If this is showing drag, is a rear pan going to do more harm than good on a bluff back car? If this is showing lift, is it saying that lift is increased or decreased on a bluff back car?
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Almost all my driving is done 1-5 miles at a time.
Best short trip: 2.4 l/100 km, 3.9 km