扩压器扩压角度对轴流风机噪音的影响

Influence of diffuser on noise of axial-flow fan

针对某大型轴流风机噪声高的问题,提出了一种通过改进圆锥形扩压器角度设计,以此来降低风机气动噪音的数值模拟分析方法。首先,以某蒸发空调用轴流风机为研究对象,利用风洞实验台和声学实验室,分别测试了该风机的性能及其噪音特性;然后,基于LES方法和FW-H方程相结合的声类比方法,采用Fluent对其进行了模拟计算,并将结果与风机的流动和声场实验结果进行了对比验证;最后,利用数值模拟的方法,分析了3种圆锥形扩压器扩压角度(8°、9°、10°)对风机静压恢复系数和噪声频谱的影响。研究结果表明:(1)3种不同扩压角度的扩压器均能降低风机的气动噪声;(2)当扩压角为9°时,风机出口处的旋涡明显减小,静压恢复系数最大为0.654,且与无扩压器相比,人耳最敏感区域2000 Hz~4000 Hz的噪声降低幅度最大,可降低4.7%。该研究可为该类轴流风机的降噪提供参考。

Aiming at controlling the noise radiated from an large axial-flow fan,the numerical study was conducted to study the influence of conical diffuser angle design on the aerodynamic noise of the axial flow fan.Firstly,the flow and acoustic characteristics of an evaporative cooling axial fan were investigated through the experiments conducted in a wind chamber and anechoic chamber.Moreover,the flow field was simulated using the large eddy simulation(LES)method,and the aerodynamic noise was predicted using acoustic analogy based on the Ffowcs Williams-Hawkings(FW-H)equation.Then simulation results were successfully validated compared to the performance experimental data of the axial flow fan.Finally,the impacts of three diffuser angles(8°,9°,10°)on the static recovery coefficient and the noise spectrum were numerically analyzed with Fluent.The results show that three conical diffusers could made a decrease in the aerodynamic noise.The research results show that:(1)the diffusers with three different expansion angles can reduce the aerodynamic noise of the fan;(2)when the diffusion angle was 9°,the vortex at the fan outlet was significantly reduced,the static pressure recovery coefficient was 0.654,and the Compared with no diffuser,the noise reduction in the most sensitive area of the human ear from 2000 Hz to 4000 Hz was the largest,which can be reduced by 4.7%.This study can provide a reference for reducing noise reduction of axial fans for large-scale evaporative air conditioners.