Analysis of the pump-turbine cavitation with small guide vane opening on pump mode

Abstract Cavitation is the main factor affecting the secure and stable operation of pump-turbine units. In this paper, a prototype of pump-turbine with splitter blade was chosen for analysis. The three-dimensional numerical calculation of the entire flow passage is carried out for the pump model under different cavitation number with small guide vane opening, and analysis the flow behaviour and cavitation phenomena. The calculated critical cavitation number is consistent with the experimental results. It is found that the cavitation mainly occurs at the runner long blade low-pressure edge, and large vortices are generated between the pressure surface of the long blade and the suction surface of the splitter blade flow channel. The combined effect of cavitation and vortex hinder the flow in the runner blade to blade channels, which makes the flow pattern in the runner and it’s downstream become more complex, which further leads to large hydraulic energy losses in the vanes and spiral case domain.