Computational fluid dynamics−discrete element method simulation and experimental study of particle transport mechanism in a centrifugal pump

Pumps are one of the most important equipment in deep-sea mining system, which transport particles continuously from the seafloor. In this paper, the computational fluid dynamics−discrete element method (CFD−DEM) numerical simulation was used to analyze the effect of particle volume fraction (PVF) on the particle transport mechanism in the pump. The reliability of the CFD−DEM numerical simulation was verified by high-speed photography experiments. The results show that the particles mainly move along the blade pressure surface (BPS) in the impeller, and the particles can suppress the formation of low-velocity vortices on the BPS. The translational velocity of the particles is less affected by the PVF, but has a significant effect on the rotational velocity. The flow pattern of particles inside the volute is categorized into wake flow, cutting flow, and near wall flow. With the increase in PVF, the particles are subjected to pressure gradient force, drag force, and virtual mass force in the pump gradually increase, but the lift force on the particles gradually decreases. The tangential force and normal force between particles increased with increasing PVF, and the increase in PVF from 2% to 10% was 462.55% and 148.17%, respectively. The collision frequency per unit time of particles with volute is the largest, but the collision frequency per unit time and per unit area is the largest for impeller. The most significant impact work of particles with volute and particles with blades is 371.08% and 505.66% when PVF increases from 2% to 10%. This study can provide theoretical guidance for the optimal design of solid−liquid two-phase pumps.