Sensitivity analysis on the influence factors of clearance axial force of a varying-speed centrifugal pump

Abstract

Hydraulic axial force is an important parameter of the performance of centrifugal pump. It strongly affects the operation stability and the life-time of thrust bearing. Under the influence of flow pressure distribution, the hydraulic axial force of centrifugal pump has mainly two parts. One is the force inside impeller while the other is the force in clearance. In this case, the situation is more complex because the pump operates with varying-speed. Under the influence of rotation speed, pump head and minimum clearance width, the variation law of clearance axial force is still not fully understood. Therefore, the orthogonal experiment is conducted based on Large Eddy Simulation (LES). The local flow and hydraulic axial force in impeller shroud clearance is mainly studied. Results show that the pressure difference between impeller inlet and outlet will strongly impact the pressure distribution in clearance. Then, it affects the clearance axial force. The rotation speed and pump head are proved influential. However, range analysis shows that the minimum clearance width is the most dominant factor. It can somehow adjust the pressure distribution in clearance. The geometric design of impeller clearance will be important in reducing hydraulic axial force especially for varying-speed centrifugal pumps.