Dynamic Stall Characteristics of Thick Wind Turbine Airfoils

ABSTRACT This paper studies the dynamic stall characteristics of thick flatback and nonflatback wind turbine airfoils. Two airfoils with a maximum thickness of were studied, with trailing edge thicknesses of and , 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 and dynamic reduced frequency ranging from to . 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.