Noise-reduction mechanism of bionic coupling blade based on the trailing edge of goshawk wing

A structural model of the bionic blade was established using the reverse reconstruction technique to extract the noise reduction characteristics of the non-smooth trailing edge shape of the goshawk wing. The LES with the Smagorinsky model and the FW-H equation based on Lighthill acoustic theory were adopted to simulate the flow field and the sound field of the bionic non-smooth trailing edge blade and the smooth blade. The aerodynamic noise control mechanism of the bionic tooth shaped trailing edge blade was examined on the basis of the analysis of the influence of the bionic tooth shaped structure on the trailing edge flow field. The results show that compared with the smooth blade, the total A-weighted sound pressure level of the bionic tooth shaped trailing edge blade decreases by 9.8 dB. The bionic structure changes the distribution of the peak aerodynamic noise, reduces the peak size, and in most of the frequency range, the aerodynamic noise drops. The bionic non-smooth trailing edge of the blade changes the location of vortex shedding in the different cross-section and increases the distance between the corresponding vortex centers, thus suppressing the chaotic flow in the wake region effectively. Therefore, for the bionic blade, the unsteady pressure pulsation on the blade surface is inhibited and the aerodynamic noise caused by the wake vortex is reduced.