Pressure distribution characteristics in pump chamber and axial force optimization of reactor coolant pump

The aim of this study is to analyze the causes and mechanisms of axial force generation in the nuclear reactor coolant pump (RCP) through experimental and numerical simulation methods, so as to investigate the hydraulic design methods to reduce the axial force. The axial force of the RCP model and the pressure values at the monitoring points of the pump chamber were obtained through model experiments, and the flow visualization was constructed using numerical simulation methods. It is found that the outer-side force Fo has the greatest influence on the axial force, the essence of which is the pressure of the liquid in the front and rear pump chambers on the shroud and the hub of the impeller, and the size of the pressure increases with the increase in the radius, and is related to the impeller outlet pressure. By adjusting the combination of impeller exit angles, the impact on axial force was investigated. It was found that reducing the exit angle near the hub can significantly lower the fluid pressure in the rear pump chamber, thereby reducing the axial force acting on the impeller, while maintaining the hydraulic performance of the pump unchanged. The conclusions of this study can serve as a reference for improving the operational safety and service life of RCPs.