Comparative research on pressure pulsations during the pump-trip of pump turbines using splitter-blade runner and full-blade runner

With the increase in hydropower capacity, splitter-blade runners have been progressively adopted in pump turbines to improve their hydraulic stability. However, their influence on pressure pulsations during pump-trip processes in pumped-storage units remains unclear. This work employed a one- and three-dimensional coupling flow simulation approach to numerically simulate pump-trip processes in units equipped with conventional runners and splitter-blade runners, respectively. The time-frequency combined analysis approach was applied to analyze the time-frequency distributions of pressure-pulsation signals, while internal flow-field analysis was conducted to reveal the underlying mechanisms. The results showed that splitter-blade runners effectively suppressed both the spatial extent and intensity of the high-pressure outlet backflow vortex during pump-trip events, thereby reducing the vaneless space pressure pulsations induced by localized backflow vortex and mitigating hydraulic-thrust fluctuations under transient conditions. These findings provide valuable references for runner design optimization in pumped-storage units.