Investigation on aerodynamic noise for leading edge erosion of wind turbine blade

Wind turbine blade is extremely prone to leading edge erosion under complicated operation conditions. This decreases the aerodynamic performance and power generation efficiency of wind turbine. Currently acoustic-based erosion detection of the blade still faces a significant challenge. Consequently, this paper presents aerodynamic noise mechanism of the eroded blade using the computational fluid dynamics method. The Zonal Detached Delay Eddy Simulation turbulence model is applied to obtain the three-dimensional instantaneous turbulent flow field. Then the far-field aerodynamic noise is carried out using the Ffowcs Williams and Hawkings approach. Simulations are performed for the erosion condition that determined by the length and depth at leading edge of 5-MW National Renewable Laboratory wind turbine. Results indicate that erosion leads to unsteady pressure pulsation near the leading edge, decrease of surface pressure difference in tip area, increase of airflow separation region and forward movement of separation point. Furthermore, the eroded blade achieves higher acoustic level than that of the normal one. From the noise directivity of wind turbine blade, erosion causes obvious asymmetry of noise pattern in the upwind and downwind directions.