离心风机振动噪声及压力脉动实验研究

Experimental Study of Vibrations, Noises and Pressure Fluctuations of Centrifugal Fan

利用传声器、加速度计、微型精密压力传感器对离心风机噪声、管道振动及压力脉动进行测量分析。结果表明,在风机噪声、管道振动、压力脉动频谱中与叶轮转动相关的离散分量明显,旋转频率分量最大;离散频率处噪声、振动与压力脉动相干函数值在0.5以上,而宽频分量处的相干函数值较小;管道内强烈压力脉动主要在距离风机出口5D (D为管道水力直径)的范围内,强度与参考动压ρv^b^2/2(ρ为流体密度,vb为体积速度)相当;在10D以后,管内流场趋于均匀,压力脉动值约为参考动压的20%;压力脉动频谱中旋转频率分量最为明显,其幅度在风机出口2D～4D附近达到最大,为参考动压的25%左右。

Microphones,accelerometers,and pressure transducers were used to measure the centrifugal fan noises,pipe vibrations and pressure fluctuations respectively.The results show that in the spectra of the fan noises,pipe vibrations and pressure fluctuations,the discrete frequency components related to the impellor rotations are notable,and the rotational frequency(RF)components are the maximum in general.The coherence of the noises and vibrations with the pressure fluctuations is higher than 0.5 at discrete frequencies,but lower at broadband frequencies.The most intensive pressure fluctuations are within 5 D from the fan outlet,where D is the pipe hydraulic diameter,with the strength almost equaling to the reference dynamic pressure ρv_b^2/2(ρas fluid density,vbas bulk velocity).After 10 D where the flow became quite uniform,the amplitude of pressure fluctuations is approximately 20% of the reference dynamic pressure.The RF components are the most conspicuous in the pressure fluctuation spectra,and the maximum valute is around 25% of the reference dynamic pressure occurring within 2 D^4 Dfrom the fan outlets.