CFD-DEM Simulation of particle transport in solid–liquid flow within a semi-open centrifugal pump

Semi-open centrifugal pumps are widely used in energy systems, particularly for handling multiphase flows in industrial, municipal, and energy generation applications. While the semi-open impeller design offers advantages in managing solid–liquid mixtures, it also presents challenges such as leakage flow and flow instability, which can significantly affect both energy efficiency and overall operational performance. Despite substantial research utilizing conventional numerical approaches, such as Eulerian-Eulerian and Euler–Lagrange models, a comprehensive understanding of the intricate interactions between solid particles and the fluid remains insufficient, particularly regarding the impact of particle behaviour on fluid dynamics and system energy dissipation characteristics. This work aims to investigate the two-phase flow behaviour and energy dissipation mechanisms under the influence of leakage flow in semi-open impellers by integrating Computational Fluid Dynamics (CFD) with the Discrete Element Method (DEM), coupled with normalized scale-averaged wavelet spectrum and coherence analysis. The results reveal that increasing the particle volume fraction intensifies particle-blade collisions, disrupting vortex structures and compromising hydraulic stability, while larger particles exacerbate flow disturbances, leading to efficiency losses of up to 12.90%. Furthermore, the energy fluctuations generated by particle-fluid interactions predominantly manifest as high-frequency pressure pulsation signals. A mutual suppression effect between the pressure pulsation signals and particle energy dissipation is observed at the blade passing frequency. These findings offer critical insights into the influence of particle dynamics on pump performance and provide valuable guidance for optimizing pump design to improve operational stability and energy efficiency in solid–liquid flow applications.