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This paper measured the propagation law of the acoustic radiation of certain airfoil blade in the near wake and obtains the noise parameters with different tip-speed ratio and measuring position by using the PULSE system. The results show that in low frequency band the rotation fundamental frequency and harmonic of the blade is main ingredients in the acoustic radiation of the near wake. With the harmonic number increasing, the energy of the acoustic radiation decreases and the noise of the middle blade is stronger than the noise of blade tip. The vortex structure leads the speed uneven distribution along the wing span. The test section presents three different regions which have obvious characteristics and the three regions are affected by the center vortex, the tip vortex and the free diffusion with the increase of the testing radius. The experimental results reveal preliminarily the propagation law of the noise radiation in the near wake and provide reference for the subsequent study.

Experimental Study on the Noise Distribution Law in Sound Field of the Horizontal Axis Wind Turbine Near Wake