离心泵内空泡演化与其对振动的影响

对不同流量下离心泵内稳态及旋转空化进行了可视化研究,获得了不同汽蚀余量下空泡团形态,同时对泵体振动进行了测量,分析了泵体振动与空泡团形态之间的关系。试验结果表明:压力面上发生空化将加剧振动,尤其是发生超空化后更加显著。多数情况下吸力面上空泡团较薄,且吸力面发生空化对振动影响相对压力面较小。旋转空化发生后振动减弱,处于正对位置的流道内空泡团形态基本相同,空泡团脱落频率约为27 Hz,压力面出现稳定空化后振动开始回升。

Evolution of Cavitation Bubbles and Its Influence on Vibration in Centrifugal Pump

Visual analysis illustrated the steady and rotating cavitation in a centrifugal pump at different flow rates. The cavity structures under different NPSH were captured and the cavity lengths, including the supercavity length were obtained. The corresponding vibrations of the volute and bearing were measured by using acceleration sensors. The influences of the cavity structures on the vibrations were analyzed. Experimental results showed that the vibration was increased when the cavitation occurred at the pressure side, especially when the supercavitation occurred. The cavitation at the suction side was usually thin and its influence on the vibration was relatively small. The growth rate of the cavity length at the pressure side was increased after the appearance of supercavitation. At the flow rates of 0.6Qd and 0.8Qd, the vibration turned from increase to decrease soon after the rotating cavitation appeared, and the ratios of the cavitation number to attack angle at the turning point were close to each other. And then the vibration was increased again when the stable cavitation occurred at the pressure side, and finally it was decreased sharply when the pump head was extremely small. Besides, the vibration was increased when large shedding cavities blocked the flow channel. During the rotating cavitation, the cavity structures in the opposite channels were similar to each other, and the cloud shedding frequency was around 27 Hz according to visual observations and the fast Fourier transform of inlet pressure fluctuations.