Abstract：To reduce the noise of the axial fan and improve its aerodynamic performance, the causes of the noise and the mechanism of noise reduction in the internal flow field were studied. Three approaches were proposed to optimize the design of the blade trailing edge. All the approaches were carried out via modeling and simulation of an axial fan blade. The diagnostic method of boundary vorticity flux (BVF) was used to analyze the results of the simulation, which were verified by experiments. The results show that the diagnostic method of BVF can be used in analyzing the cause of the eddy. It is an efficient way to investigate the mechanism of the internal flow based on the variation of the eddy and the distribution of the internal flow field. The eddy in the blade trailing edge is the main reason of the noise, and the serrated trailing edge approach, which can reduce the eddy in the blade trailing edge, can significantly reduce the noise. In addition, a reference structure of the trailing edge is proposed, which can make a contribution in the reduction of the aerodynamic noise.
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