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Old 08-28-2011, 04:02 PM   #44 (permalink)
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Join Date: Apr 2011
Location: San antonio TX
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GoldSunshine - '03 Pontiac Grand AM SE2
90 day: 28.82 mpg (US)
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Vortex Generators size angle

New guy first post, long time tinker/techie.
Seems like the placement of the VGs and size have a affect. Search.. Vortex Generators: Band-Aids or Magic?
This is where driving around with wool strings come into play to find where the transition from laminar flow and turbulent flow happens (based on the speed we need to improve mpg..remeber the air characteristics changes with speed). Based on were the transition happens, we need to make a few needle thin poles (as not to disturb airflow) with sowing thread sized strings to try to find the hight of the boundary layer hight. I guess a roof monted camera can come into play here since you'll need magnification from the next car to see the results. knowing the hight of the poles we can now know the hight of the boundary layer and subtract 20% to get 80% of which the vg hight will be. The angle of attac of the vg seems like it depends on how fine the VGs will be. Think of the vortex as springs trailing behind the VGs. 45 degrees fine packed coils, 10 degrees stretched spring. Think this will depend on the speed of the car. low speed on the car the finer the vortex need be, the faster the speed the more loose the vortex need be. Then the lenth of the VGs. How big the vortex will be. How much ground you wanto cover across the sides of the car. But speed also factors here. I might be wrong. I'm going to try to test this.
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