Noise reduction of bionic coupling blades of horizontal axis wind turbine

Many bio-inspired researches for aerodynamic noise control of wind turbine have been carried out and obtained effective results. Inspired by the silent flight of owl, in this paper, the airfoil of owl's wing and the asymmetric sawtooth structure of the feather have been extracted and reconstructed on the prototype wind turbine blades. The bionic airfoil blade and bionic coupling blade have been designed separately and compared with prototype blade. To obtain the asymmetric sawtooth structure with better acoustic performance, the sawtooth parameters are selected by orthogonal test. The influence of airfoil and asymmetric sawtooth for acoustic performance of blade has been investigated with large eddy simulation method and Ffowcs Williams-Hawkings analogy method. The results show that the bionic coupling blade has a larger surface pressure difference compared with the prototype blade and thus has better aerodynamic performance. The airfoil-structure coupling method can effectively reduce the aerodynamic noise of the blade without affecting the directivity of the acoustic, and optimized blade can reduce the noise by up to 8.42 dB. The blade coupling airfoil has an inhibitory effect on intermediate and high frequency noise. After adding asymmetric sawtooth trailing edge, the noise in the low frequency and intermediate frequency range is further reduced.