Numerical prediction of cavitation performance of a prototype pump as turbine based on CFD

Centrifugal pump as turbine (PAT) is a crucial technology for recovering and utilizing liquid pressure energy, but its cavitation behavior remains insufficiently understood. To investigate the cavitation performance of a specific pump operating as turbine, this study systematically analyzed its behavior across varying flow rates using computational fluid dynamics (CFD) based on the Schnerr-Sauer cavitation model. The results show that the incipient and critical cavitation margins reach their minimum values at the optimal flow rate, closely matching those under low flow conditions. When flow rate exceeds the optimal point, both margins increase significantly. At optimal and high flow rates, the cavity volume inside the impeller first increases and then decreases as cavitation evolves, peaking at the critical cavitation point. The impeller cavity volume grows with increasing flow rate, while draft tube cavity volumes continuously expand as cavitation progresses.