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Hi All,
I drove around for a week with tufts behind turbulators the upper 1/3 of one A- pilar. When the conditions were windless, one could see the tufts flowing horizontal on the turbulator side without any motion. On the side without the turbulator the tufts were trailing with about a 15 degree up angle and with some small oscillating motion.
Even slight cross winds completly changed this, however. If the wind came across the car, to the turbulator side, the tufts ran at a 15 degree or more up angle. So, the turbulator benefit was lost completely.
Based on this, I put turbolators on both sides of my Prius. Still, I think there is a possibility that drag is incressed with the Prius.
On cars with higher windshield rakes, the advantage may be more. The issue is that the air is pushed sideways around the edge of the A-pilar. In the Prius the air is at about a 60 degree up angle across the windshield. In other cars it may be more horizontal. When the flow into the A-pilar area is horizontal and pushes out into the slip stream by its own momentum, it will begin to turn over, and turn into vortex. The purpose of the tubulators is to use the cross flow momentum to trip the air into a slip-stream direction.
My guess is there may actually be an optimum windshield angle for vortex formation. Anybody have any info on this? Aerohead ?
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