离心泵压力脉动对流动噪声影响的试验研究

Experimental study on impact of pressure fluctuation on flow-noise in centrifugal pump

为了研究离心泵内部压力脉动和流动噪声在不同工况下的变化规律及其关系,采用试验方法,用高频压力传感器和水听器分别采集离心泵出口脉动压力和流动噪声信号,并进行时频域和自功率谱分析.结果表明:各工况下,叶片通过频率是压力脉动和流动噪声的主频,这是由叶轮和蜗舌之间的动静干涉引起的,而流动噪声在轴频二倍频(44.8 Hz)和224.8 Hz处也有明显峰值,这是由叶轮叶片数和蜗壳壳体振动引起的.小流量和设计流量下,流动噪声频谱与压力脉动频谱形状比较相符,流动噪声可以近似看作是由压力脉动引起的;随着流量的增大,流动噪声频谱除了包括压力脉动的主频外,还包括汽蚀和湍流等引起的500 Hz以上的高频部分.

In order to study the rules of pressure fluctuation and flow-noise change under different flow conditions in a centrifugal pump,and to find the relationship between pressure fluctuation and flow-noise, the frequency spectra of pressure signals and noise signals collected by high-frequency pressure transducer and hydrophone located at the pump discharge have been obtained with experimental method. The results show that the blade passage frequency dominates for all operating conditions, which manifests that the flu- id-structure interaction between the rotating blades and the volute tongue may be the primary source of pressure fluctuation and noise generation. The flow noise frequency spectra has evident peak at the second multiple of the rotating frequency and 224.8 Hz, which is caused by the number of blade and the volute vibration. The frequency spectra of pressure fluctuation and flow noise are unanimous for small flow, and the flow noise may be predicted with the pressure fluctuation. But with the increase of flow, the high frequencies above 500 Hz and the blade passage frequency appear in the flow noise frequency spectra, which implies that the flow noise is partly caused by cavitation and turbulence, except pressure fluctuation for these operating conditions.