Effect of particle size on vortex structure and erosion behavior of semi-open centrifugal pump

The erosion problem of semi-open centrifugal pump serving in silt-carrying fluids is serious, and the interaction between the particle migration and vortex evolution aggravates the complexity of erosion on the flow components. In the present paper, the liquid-solid two-phase flow of semi-open centrifugal pump under different particle sizes is simulated based on the four-way coupling Euler-Lagrangian method, in which the fluid-particle interaction and particle-particle interaction are taken into account. In particular, the influence of particle size on the structure characteristics of leakage vortex and erosion characteristics are investigated, and the interrelationship among vortex structure, particle migration and surface erosion behavior is revealed. The results show that the erosion area is mainly distributed in the blade leading edge, the pressure surface leading edge and the hub. When the particle size is 0.1 mm and 0.3 mm, due to the good following characteristic of particles and the inhibition effect on tip leakage vortex (TLV), the particles are easy to impact the trailing edge of blade suction surface and the hub, which induce severe erosion. As the particle size decreases, the number of particles flowing into the tip clearance increases. Therefore, the frequent impact of particles on the TLV leads to the breakup, separation and fusion of the vortex, which aggravates the flow instability. This paper provides a new insight into the hydraulic performance and erosion characteristics of semi-open centrifugal pump in terms of particle-vortex interaction.