Based on the analysis of pressure pulsation characteristics of the vaneless zone of the pump-turbine

In hydropower stations, hydraulic turbine performance critically affects power generation efficiency and safe operation, with optimization under variable conditions being particularly significant. This study uses numerical simulation and computational fluid dynamics to analyze hydraulic performance and pressure fluctuation characteristics under different heads and guide vane openings, combining runner prestressed modal characteristics to explore pressure fluctuation mechanisms and low-order vibration patterns, providing a basis for structural optimization and stable operation. A 3D model of the entire flow channel was built using standard k-ε and SST k-ω models for steady-state and transient computations. Results show that the turbine has an efficient operating region under the rated head, with hydraulic losses concentrated in the runner. Pressure pulsation characteristics vary by zone: intense and regular in the bladeless region and runner passage; strong and regular at the runner blade inlet but less so at the outlet. Water head and opening variations affect runner natural frequencies and vibration modes, with low-order modes mainly involving multi-directional vibrations. These findings support pump-turbine optimization, guide similar research, enhance turbine efficiency, ensure station safety, and promote hydropower sustainability.