Numerical exploration of tip leakage vortex cavitation in a waterjet pump

Tip leakage vortex (TLV) cavitation poses significant challenges to the efficiency and stability of axial waterjet pumps. This study performed numerical simulations to analyze the evolution of flow and vorticity fields under various cavitation conditions and investigated the impact of cavitation on pump performance. The results indicated that cavitation development exacerbated flow separation on the blade surface, significantly increasing flow instability and complexity in this region. Cavitation exerted a dual effect on vortex evolution. It promoted TLV development at high cavitation coefficient (N^*) values, which caused TLV breakdown via vortex interaction at N^* = 1.076. Meanwhile, it inhibited TLV formation while affecting the secondary TLV at lower N^* values. An examination of the components of the vorticity transport equation indicated that cavitation hindered the stretching of the primary TLV and altered the spatiotemporal distribution of the Coriolis force. Pressure pulsation and force analyses indicated that low N^* values induced strong interactions among the impeller outlet cross-section, cavitation-induced TLV, and tail vortices, significantly increasing the amplitude of pressure pulsation.