Effects of impeller trimming on energy loss and coherent structures evolution of a vortex pump

Under the “dual-carbon” strategy, the demand for energy-saving pump equipment has become increasingly prominent. This study examines how impeller diameter trimming affects the hydraulic performance and internal flow structures of a vortex pump by systematically analyzing two regions (the impeller domain and the chamber) with combined numerical simulations and experiments. The results indicate that as the trimming ratio increases, the pump head and efficiency decrease. In particular, when the trimming ratio exceeds 9%, the internal flow exhibits significant load imbalances, enhanced energy dissipation, and disordered vortex structures. By employing rigid vorticity identification and the finite-time Lyapunov exponent methods, the mechanism of flow instability and energy degradation caused by impeller cutting is revealed. This study establishes a coupling relationship among impeller trimming, flow stability, and energy–transfer efficiency in vortex pumps, providing theoretical support for the optimization and operation of impeller–trimming technology and offering a reference for analyzing similar fluid machinery.