不同转速下离心泵压力脉动的试验研究

离心泵的压力脉动对泵的安全稳定运行有重要影响。为了揭示离心泵运行于不同转速下的压力脉动特性,以一台单叶片离心泵为试验研究对象,测量了泵在不同转速下的外特性曲线,并采用高频压力传感器测量了泵在不同转速时的压力脉动,获得了压力脉动的时域图、频域图,以及不同流量工况下的压力脉动强度分布曲线。外特性试验结果表明:不同转速下泵H-Q曲线基本平行,符合相似换算。试验结果表明:蜗壳内压力脉动从隔舌沿着泵转子旋转方向逐渐减弱,在额定流量工况附近压力脉动强度最小。频域分析表明:压力脉动主频为叶轮转频fn,但由于单叶片离心泵内存在较强的流动分离,在5 fn范围内也存在明显的宽频压力脉动信号。随着转速的降低,蜗壳内压力脉动强度明显降低,但并不完全符合相似换算;转速越高蜗壳-叶轮的势流干涉作用越强,压力脉动周期性越明显;在低转速小流量时尾迹干涉表现明显,压力脉动变得更复杂,周期性减弱。

Experimental Investigation of Pressure Fluctuations for Centrifugal Pumps at Different Rotational Speed

The pressure fluctuations of the centrifugal pumps have a great influence on the safe and stable operation of centrifugal pumps. In order to reveal the pressure fluctuations characteristics of the centrifugal pump at different rotational speed, a single-blade centrifugal pump is used as the test pump and the pump performance is obtained. The high-frequency pressure fluctuations sensor is used to measure the pressure fluctuations of the pump at different rotational speed. The pump performance test results show that the H-Q curves at different rotational speed are basically parallel, which is consistent with similar conversion. The pressure fluctuations test results show that the pressure fluctuations in the volute gradually weaken from the tongue along the direction of the impeller rotation, and the pressure fluctuations intensity is the smallest near the design flow condition. The frequency domain analysis shows that the dominant frequency is the impeller rotational frequency fn, but there is also a significant broadband signal in the range of 5 fn. Pressure fluctuations intensity decreases remarkably with the decrease of the rotational speed, and the pressure fluctuations intensity does not completely match the similar conversion of the rotational speed. The higher the rotational speed, the stronger the potential flow interaction of the volute and impeller, also the stronger the pressure fluctuations periodicity. And the wake interaction is obvious at low flow rate and low rotational speed, thus the pressure fluctuations become more complicated and the periodicity becomes weaker at low flow rate and low rotational speed.