Influence of particle concentration on pressure fluctuation characteristics of energy transfer in solid-liquid semi-open centrifugal pump

The stable and efficient operation of centrifugal pumps plays a critical role in liquid-based energy storage and energy conversion systems, where particle laden working fluids are often encountered. However, the interaction between turbulent leakage flows and dispersed particles can lead to performance degradation, including excessive energy dissipation and pressure fluctuation. In this study, solid-liquid two-phase flow characteristics in a semi-open impeller centrifugal pump are analyzed from an energy perspective. Particular emphasis is placed on elucidating the influence of particle volume concentration (Cv) on energy dissipation, hydraulic performance, and flow-induced unsteadiness. The results indicate a nonlinear dependence of pump performance on particle concentration, with the response strongly modulated by flow rate. At low concentration, the increase in effective mixture viscosity suppresses near wall turbulence, resulting in moderate improvements in head and efficiency. When Cv>5%, intensified particle collisions and wall impacts substantially increase energy dissipation, leading to a pronounced decline in hydraulic performance. Particle induced disturbances promote the breakup, shedding, and merging of vortex clusters in the leakage flow, thereby amplifying internal flow instability. Analysis of the vorticity transport equation identifies the Coriolis force and viscous diffusion as the dominant contributors to vortex dissipation. Energy loss is primarily concentrated within the impeller, with the region near the rear cover plate exhibiting strong unsteadiness due to elevated particle impact frequency. Pressure pulsation analysis shows that the tip clearance region is characterized by low frequency, high amplitude fluctuations, while the mid span region exhibits two dominant frequencies at 0.1fn and 5.2fn that increase monotonically with particle concentration. These findings elucidate the mechanisms of particle induced energy dissipation and unsteady flow, thereby providing guidance to enhancing efficiency and operational stability in particle-laden energy storage systems