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Aerodynamic Effects of Rear Spoiler and Vortex Generators on Passenger Cars (PDF Download Available)
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RESULTS AND DISCUSSION
A total of 26 combinations are tested for the car model by changing the flow angles (= 0and 30), spoiler angles (=0and 45) andorientations of vortex genartors (co-rotating and
4counter-rotating) in order to find out the optimum conditions for which drag coefficient is minimum. The following conclusions can be drawn based on this experiemntal studies.Referring to Fig. 7, a marked improvement in static pressure along the car roof, especially at the car rear that is noticed at a flow angle () = 30by subsequent use of rear spoiler (at = +45) and co-rotating vortex generators. Here,the suction reduces to an extent and become very close to zero static pressure values near the rear end of the car. This incident clearly indicates that the flow separation zone gets reduced with the use of spoiler along with VG. It is also observed in Fig. 7(a to c) that a positive pressure builds up on a little portion of the car roof close to the windward side
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There is more in article, but it is clear that at least in combination with rear spoilers VGs help to reduce aerodrag.