Dynamic stall control of an offshore wind turbine airfoil using a leading-edge microcylinder

Abstract

This study conducted a computational investigation to examine the impact of passive flow control using a microcylinder positioned near the leading edge of a dynamically stalled NACA0012 offshore wind turbine airfoil at a Reynolds number of 1×106. Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations were used for parametric analyses to determine optimal control parameters, while Delayed Detached Eddy Simulation (DDES) provided insights into the transient vortex structures on the airfoil's suction surface, elucidating the control mechanisms of the microcylinder. The results reveal a strong correlation between the microcylinder’s effectiveness and its geometric configuration, particularly its diameter and distance from the airfoil surface. The microcylinder effectively modifies the flow field by generating vortices that interact with the boundary layer, thereby enhancing its resistance to adverse pressure gradients and delaying flow separation. The optimal configuration—characterized by a microcylinder with a diameter of 1% of the chord length (D/c = 0.01) positioned 1.5% of the chord length (L/c = 0.015) away from the airfoil surface—resulted in a 62% reduction in peak drag coefficient and a 50% decrease in aerodynamic hysteresis loop area. These improvements significantly enhance the dynamic aerodynamic performance and stability of the oscillating NACA0012 airfoil, effectively mitigating the detrimental effects of dynamic stall.