Cavitation simulation of centrifugal pump with different inlet attack angles

Abstract

The impeller passage of low-specific-speed centrifugal pump is long and narrow. As cavitation occurs, the cavity blocks the passage abruptly, resulting in performance deterioration. Numerical simulation and a hydraulic test were conducted on a low-specific-speed centrifugal pump at three different inlet attack angles (8 º, 0 º, and −8 º) to clarify the influence of inlet attack angle on cavitation evolution in the impeller. The cavity distribution in the cavitation flow field and the blade loading distribution were analysed. Results showed that as the cavitation number decreased, the cavity initially emerged on the suction surface of the blade leading edge then extended rapidly to the impeller outlet along the blade surface. Meanwhile, the cavity spread to the pressure surface from the suction side under the influence of the re-entrant jet. Pump performance sharply deteriorated as the cavity grew to about 1/3 of the blade length. The loading on the blade close to the tongue was higher than that on the other blades regardless of whether cavitation occurred or not, and the zero-loading zone at the complete cavitation stage occupied about 3/5 of the length of flow passage.