Investigation of leading-edge protuberances for the performance improvement of thick wind turbine airfoil1

Abstract An effective flow separation control method is urgently needed to improve the aerodynamic performance of the thick wind turbine airfoil. The purpose of the present study is to explore the effect of leading-edge protuberances (LEPs) on the aerodynamic performances for thick wind turbine airfoil during stall region. A direct force measurement technique employing three-component force balance was used to analyze the aerodynamic characteristics of airfoils with LEPs at a Reynolds number of Re = 2 × 105 through the wind tunnel experiment. Particle Image Velocimetry measurement was also performed to understand the effects of LEPs on flow separation and to correlate these effects with the aerodynamic performances of airfoil. The mean velocity and vorticity results indicate that the LEPs can effectively suppress flow separation for the thick airfoil in the stall region, moreover the airfoil with smaller amplitudes and wavelengths tends to perform significantly better in flow separation control. The LEPs method promotes the wavy airfoil with a better flow separation characteristics, which can effectively improve the aerodynamic performance and reduce the intensity of aerodynamic fluctuations for the thick airfoil. In addition, the stall process of the wavy airfoil is much gentler without sharp deterioration. Therefore, the LEPs method can help maintain high aerodynamic performance and prevent structural problems for the inboard region of wind turbine blades.