Aerodynamic Noise Reduction Based on Bionic Blades with Non-Smooth Leading Edges and Curved Serrated Trailing Edges

The flight of the owl is silent owing to non-smooth leading edges of the owl’s wings and the curved serration of the feathers. This study applied this concept of bionics to blade design for horizontal axis wind turbines to reduce aerodynamic noise. The flow and sound field distribution around a rotating wind turbine with three blades were investigated. A numerical simulation method that combines large eddy simulation (LES) and FW-H acoustic equation was adopted to compare aerodynamic noise between the blade prototype and the bionic blade. The comparison revealed that the sound pressure level of the bionic blade was reduced over middle and high frequencies, thereby achieving a noise reduction of 6.9 dB. The intensity of the wake vortex shedding of the bionic blade was lower, and the interaction between the shedding vortices in the bionic blade was smaller compared with that in the prototype blade, indicating that the aerodynamic noise induced by the shedding vortex was effectively reduced.