Experimental and numerical study on a new noise reduction design for a small axial fan

Abstract

The broadband noise of an axial fan is highly related to the vortex shedding at the blade trailing edge and the secondary flow at the blade tip. Herein, a circular arc design is proposed to modify the shape of blade tip and trailing edge together with the features of simple structure and easy manufacture. The experimental and numerical studies were conducted to investigate the effect of circular arc design on the aerodynamic and acoustic characteristics of a small cooling axial fan through the experimental method of the semi-anechoic chamber and LES simulation combined with FW-H. The tested and calculated results show that the SPE of the fan with R7 circular trailing edge can be improved for the entire flow rate range. And the SPC is decreaed as the increasing of arc radius. For the fan with R7, the SPE can be increased by 2.1% and the SPC is decreased by 4.8% at the designed flow rate. In terms of acoustic characteristics, the modified impeller can suppress the broadband noise in the range of 1000 ∼ 3000 Hz, and this suppression can be improved with the growth of flow rate. The R7 design shows the best noise reduction performance, with 2.4 dB reduction over the prototype.