Numerical investigation of the blade tip leakage vortex cavitation in a waterjet pump

Abstract

The blade tip leakage vortex (TLV) cavitation is a concern for hydraulic machineries. The underlying mechanism of the TLV cavitation is complex due to the interactions between the vortical flow and cavities, leading to the necessity of improving the numerical methods. In consideration of the influence of the angular momentum on the vortex cavitation, the Zwart's cavitation model is improved by adjusting the condensation coefficient based on the vortex intensity. The modified cavitation model is used to investigate the TLV cavitation from a waterjet pump. The energy characteristics of this pump and the cavitation phenomena near the blade tip are validated by the referenced experiment. The blade tip leakage flow and the TLV cavitation features are revealed by present simulation under different cavitation conditions. It can be found that both the TLV and its cavitation reduce the leakage flow rate through the rotor tip. According to the analysis of the pressure fluctuation characteristics, it shows that the TLV cavitation especially its terminal region enhances the pressure pulsation. With the decreasing of the cavitation coefficients, the amplitude of the pressure fluctuation is increasing and the corresponding positions with the maximum pulsation migrate to the downstream. • The blade tip leakage vortex cavitation characteristics for an axial waterjet pump are numerically studied. • An improved Zwart's cavitation model is used and evaluated. • The vortical flow features near the blade tip are investigated on different cavitation conditions. • The tip leakage vortex cavitation enhances the pressure fluctuation at the rotor casing.