Pneumatic Turbulators - A Device for Drag Reduction at Reynolds Numbers below 5,000,000
TECHNISCHE HOGESCHOOL DELFT (NETHERLANDS) DEPT OF AEROSPACE ENGINEERING
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At Reynolds numbers below 5 million, airfoils are affected by laminar separation bubbles which, in many cases, considerably increase the drag. By blowing air from a row of orifices at the beginning of the laminar separation bubble, the bubble can be prevented and the drag can be reduced substantially. This device is called pneumatic turbulator. Free-stream total pressure is sufficient to provide the turbulator bleed air. The additional drag caused by the bleed air and the air jets is negligible. The low drag Reynolds number range of laminar airfoils can be extended by using pneumatic turbulators.