Research on the influence of Gas-Containing Incoming Flow on cavitation and flow characteristics of nuclear reactor coolant pumps

This study investigates the variation in cavitation performance of a nuclear reactor coolant pump (NRCP) under gas–liquid inflow conditions and the interaction between cavitation bubbles and entrained air bubbles in the internal flow. A computational approach combining large eddy simulation (LES) with the Mixture–ZGB model was employed to evaluate cavitation and flow characteristics at different gas void fractions, with a fixed incoming air-bubble diameter. Analyses were conducted on vapor- and gas-phase volume fraction distributions, vortex structures identified using the Q -criterion, and pressure fluctuations within the guide vanes. The results show that the gas void fractions (AVF) of 1% improves cavitation performance, while 3% and 5% degrade it. Q -criterion vortex identification reveals that cavitation increases shear vortices in the impeller and enhances vortex shedding near blades. Pressure fluctuation analysis shows increased fundamental blade passing frequency ( f BPF ) amplitude at the guide vane inlet due to cavitation, which rapidly dissipates at the outlet. These findings enhance understanding of cavitation phenomena in NRCP and provide practical guidance for their operation under extreme conditions in nuclear power engineering.