Chapter 12. Multiphase Flow Simulations of Sediment Particles in Mixed-flow Pumps

The pumps are energy conversion devices whose main goal is to convert the mechanical or rotational energy of the impeller into the fluid energy. Thus, the understanding of the various sources of energy loss and its reduction has consistently been a focal point of research to improve their efficiency and overall performance as described in Chapters 7–12 [1]. The energy loss in a pump can be categorized into the hydraulic loss, the volumetric loss, and the mechanical loss. The hydraulic loss encompasses the impact loss, the loss due to the vortex resistance, and the loss due to the friction. There have been many studies reported in the literature on the impact loss and the loss due to vortex resistance in the pumps operating with clean water as a working fluid. For example, Shi et al. [2] studied the impact loss at the impeller inlet for varying number of guide vane blades to determine an optimal number of blades to minimize the impact loss. Nie et al. [3] employed the velocity triangles concept to investigate the impeller impact loss, elucidating the impact of inlet angle and flow velocity on the loss. Li et al. [4–6] studied the energy loss caused by the internal vortex flow in the mixed-flow pumps. Ji et al. [7–9] explored the impact of the leakage vortex flow between the tips of the impeller blades on the internal flow field and hydraulic loss in the mixed-flow pumps. They analyzed the energy loss in the mixed-flow pump using the entropy generation theory and conducted the diagnostics. However, pumps are not always under clean water conditions. In practical engineering applications, pumps generally operate in a two-phase flow consisting of the solid sediment particles with water, where the loss due to friction becomes significant. The substantial friction losses occur due to interactions between the particles and the pump walls, among the particles themselves, and between the particles and the moving fluid.