Large eddy simulation of the flow energy dissipation in the blade channels of a stalled pump impeller

Abstract

Pump impellers usually work with the rotating stall phenomenon. The performance will be strongly affected by the undesirable flow. Understanding the features of flow energy dissipation is very important. In this study, large eddy simulation is conducted for the turbulent flow field based on a typical 6-blade pump impeller with “alternating stall” phenomenon. The stalled channels and well-behaved channels alternatively and stably distribute. Compared with the experimental data, the numerical simulation is proved accurate. In the well-behaved channel, flow pattern is relatively smooth. In the stalled channel, flow is completely blocked by several stall cells. Vortex shedding is well predicted mainly in three regions including the leading-edge region of stalled channel, the outlet region of stalled channel, and the blade suction side region of well-behaved channel. Turbulence kinetic energy is high in these regions. High flow energy dissipation is found among shedding vortexes due to flow-flow interaction and in the near-wall region because of flow-wall interaction. In the core region of vortexes, flow energy dissipation is not that high. The flow-flow interaction and the flow-wall interaction are two main sources of flow energy dissipation. In the well-behaved impeller blade channel with smooth flow pattern, the flow energy dissipation is mainly caused by flow-wall interaction. On the contrary, in the stalled impeller blade channel with vortical flow pattern, the flow energy dissipation is mainly caused by flow–flow interaction. The large eddy simulation-based study will be very helpful in enhancing the performance of pump impellers especially with the rotating stall phenomenon.