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.
[1]梁锡智,吴海. 轴流风机的噪声及降噪[J]. 流体机械, 1999, 27(1):30-34. LIANG Xizhi,WU Hai.Noise and noise reduction of axial fan[J].Fluid machinery,1999,27(1):30-34.(in Chinese)[2]李博,钱红玉. 叶片穿孔小型轴流风扇气动性能的研究[J].浙江理工大学学报,2013,30(1): 76-80. LI Bo, QIAN Hongyu. Aerodynamic performance study on small axial fan with perforation blades[J]. Journal of Zhejiang Sci-Tech University,2013,30(1): 76-80.(in Chinese)[3]钟芳源. 叶片机型气动声学译文集[M].北京:机械工业出版社,1987. [4]刘庆萍. 轴流风机叶片仿生降噪研究[D].长春:吉林大学,2006.[5]陆晓军. 齿形叶片降低离心式风机噪声的实验研究[J].农业机械学报,2001,32(5):86-88. LU Xiaojun. Experimental study on noise control of a centrifugal blower using tooth shape vane[J]. Transactions of the CSAM, 2001, 32(5):86-88.(in Chinese)[6]周翔. 基于CFD/CAA的轴流风扇噪声分析与降噪设计[D].成都:电子科技大学,2016.[7]FELTEN F, FAUTRELLE Y, TERRAIL Y D, et al. Numerical modelling of electromagnetically-driven turbulent flows using LES methods[J]. Applied mathematical modelling, 2004,28(1): 15-27.[8]FUKANO T, KODAMA Y, SENOO Y. Noise generated by low pressure axial flow fans, modeling of the turbulent noise [J].Journal of sound and vibration,1977,50(1):63-74.[9]CARO S, PLOUMHANS P, GALLEZ X. Implementa-tion of lighthill′s acoustic analogy in a finite/infinite elements framework[C]//AIAA paper 2004-2891,10th AIAA/CEAS Aeroacoustics Conference and Exhibit, Manchester UK, 2004.[10]YEN J, AHMED N A. Synthetic jets as a boundary vorticity flux control tool [J]. AIAA journal, 2013, 51(2): 510-513.[11]LI Q, WU H, GUO M, et al. Vorticity dynamics in axial compressor flow diagnosis and design[J]. Journal of fluids engineering, 2010, 132(1): 1-10.[12]吴宏,蒋洪德. 燃气轮机压气机涡量动力学理论及分析方法[J]. 航空动力学报,2013, 28(4):903—908. WU Hong, JIANG H D. Theory and analysis method based on vorticity dynamics for gas turbine compressor [J]. Jour-nal of aerospace power, 2013, 28(4):903-908.(in Chinese)