Slip influence on a blade performance under different pitch-oscillating motion

Abstract

Slip velocity effects on the performance of an SD7037 wind turbine blade are processed. The slip boundary condition is associated with applying a superhydrophobic coating on the leading edge to avoid icing. The computational fluid dynamics (CFD) approach and the Transition-SST (Shear Stress Transport) viscous model are applied for a pitch-oscillating and a static airfoil with a range of slip lengths at Reynolds number of 4×104. The dynamic motion of the airfoil causes the dynamic stall (DS) phenomenon. This study focuses on investigating the effects of superhydrophobicity on deep DS and resultant aerodynamic loads under different reduced frequencies. For the static blade, the slip causes significant influences on the aerodynamic coefficients at a post-stall angle of attack: the lift coefficient is increased by 20%, and the drag is decreased by 30%. The airfoil shows weak loadings at low angles of attack. For the dynamic blade under DS, the reduced frequency varies from 0.05 to 0.20. The aerodynamic characteristics have the maximum dependency on the slip boundary conditions when the reduced frequency equals 0.12. Increasing the slip length postpones the DS vortices growth and DS occurrence angle of attack, regardless of reduced frequencies.