Numerical study on flow stall and kinetic energy conversion of low-specific-speed centrifugal pump

Stall is a common phenomenon in centrifugal pumps under low-flow conditions; it has a significant impact on fatigue and can even damage mechanical structural components. Computational fluid dynamics was used to perform high-precision numerical calculations to describe multiple operating conditions in the computational domain. The accuracy of these numerical simulations was verified by comparing the results with the single-flow channel flow patterns captured by time-resolved particle image velocimetry and the external characteristics of the centrifugal pump. On this basis, the unsteady spatiotemporal evolution of the vortex structure under stall conditions and the kinetic energy conversion relationship were determined. The stall vortex under the rotating stall condition has a relative motion with the impeller in the circumferential direction between channels, with the characteristic propagation frequency fcs = 0.71 Hz. For stationary stall conditions, the critical stall condition has a greater kinetic energy dissipation compared with the deep stall condition, with energy differences being more than three times larger at the blade leading edge, where the stall vortex is formed.