抽水蓄能机组空化尺度效应对能量转换与稳定性影响的综合评估与分析

Abstract Pumped hydro energy storage is a leading large-scale energy storage technology, effectively mitigating the intermittency and uneven distribution of renewable energy sources. The motivation of this study is to addresses the lack of systematic understanding of cavitation scale effects on energy conversion imbalance and hydraulic instability in pump-turbines, which are core components of pumped hydro energy storage units. Using the largest pumped hydro energy storage unit in China as a case study, this research combines numerical simulation with experimental studies to thoroughly investigate the impact of cavitation scale effects on energy conversion characteristics, vortex characteristics, and hydraulic stability, achieving the following results and conclusions: (1) A significant negative correlation exists between cavitation scale and unit efficiency. A mathematical model was developed to describe this relationship, enabling rapid prediction of pump-turbine performance under cavitation conditions. (2) Cavitation has a significant regional impact, suppressing small-scale turbulent motion and weakening vortex activity in the cavitation area, while enhancing these characteristics and promoting vortex formation in the non-cavitation area. Increasing the cavitation scale leads to a significant decrease in stability at the blade outlet of the non-cavitation area. (3) An increase in cavitation scale results in a rapid decline in hydraulic stability. The rapid increase in potential rothalpy gradient and the intensification of reverse flow are key factors in this decline. Controlling the potential rothalpy gradient effect on the blade outlet side is crucial for enhancing stability under cavitation. These findings enhance the understanding of flow characteristics in pumped hydro energy storage units and provide valuable insights for anti-cavitation blade design.