Dynamic Stall Characteristics of Thick Wind Turbine Airfoils
M. Doosttalab (Nordex Energy SE & Co. KG, TU Delft - Wind Energy)
Carlos Simao Ferreira (TU Delft - Wind Energy)
D. Ragni (TU Delft - Wind Energy)
W. Yu (TU Delft - Wind Energy)
Christof Rautmann (Nordex Energy SE & Co. KG)
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Abstract
This paper studies the dynamic stall characteristics of thick flatback and nonflatback wind turbine airfoils. Two airfoils with a maximum thickness of (Formula presented.) were studied, with trailing edge thicknesses of (Formula presented.) and (Formula presented.), respectively. The static and dynamic experimental measurements were performed in the wind tunnel using surface pressure measurements for clean and tripped airfoils at the Reynolds number of (Formula presented.) and dynamic reduced frequency ranging from (Formula presented.) to (Formula presented.). The effects of the trailing edge gap, roughness, mean angle of attack, and reduced frequency on the dynamic stall characteristics of the airfoils were investigated. The results show that increasing the trailing edge gap delays the onset of dynamic stall. However, the lift loss after the onset of dynamic stall is for the flatback airfoil higher than the sharp trailing edge airfoil. Moreover, the flatback airfoil show higher lift overshoot compared to the sharp trailing edge airfoil in the dynamic stall condition. Increasing the reduced frequency affects the dynamic behavior both airfoils differently.
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