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Old 05-24-2020, 05:13 PM   #100 (permalink)
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Originally Posted by gumby79 View Post
Would the rear wing experiment not be just a vertical "blowen diffuser "?

What was the wind direction for the Eroding Clay test? It will help with interpretation of the results.

My interpretation based on what I see, assuming wind from the left ( American driver side)
▪ The airfoil profile has too much curve on the convex side , evidenced by severe separation less than 1/3 Cord at the bottom and 1/4 cord at the top. This would be a good application for test of VG's in a specific use case, (maintenance of attached flow in extreme angle of attack as demonstrated). I have seen a proper demonstration you're witty Edgar's work as intended to a benefit, is there room for improvement, possibly/ possible not.

¿ I'm taking it this was the downwind side?
▪ The up wind /drivers side I expect to see almost,but not quite,a poler opposite. Eg cleaned off by attached flow out side and dirty/covered by sepperated flow on the convex wing surface.

▪ the up wind turning vane / wing is acting like a blown diffuser blowing the wrong direction ,at a yaw angle between 45-180° at typical road going speeds.
E.G. By ~45° yaw (angle of attack~ 90° negative) the wing is past full stall and by ~50°ish yaw it becomes a blowen diffuser.
I understand a blown diffuser to be blown only if there is external energy applied eg via a electric motor and fan.

The eroding clay was used on only one side of the car and the car was driven in lots of different directions on a day where there were gusty winds.
Modifying the Aerodynamics of Your Road Car

A really good book that should be added to the library of everyone working in automotive aerodynamics, as well as those making car aero modifications at home. - Rob Palin, former Tesla aerodynamicist
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