Numerical simulation for influence of rear wear ring and balance hole on performance of the canned motor pump

Canned motor pumps are widely used in chemical and nuclear industries for transporting hazardous fluids. There are few studies on the effects of structural changes to the rear wear ring and balance hole on leakage and axial force in canned motor pumps, and the mechanisms for improving rear pump chamber flow have not been revealed. This paper modifies the rear wear ring and balance hole to reveal mechanisms of their impact on rear pump chamber flow and demonstrates that the improved designs reduce axial force, minimize leakage, and enhance operational stability. The results show that increasing the rear wear ring clearance width stabilizes the axial force, reaching equilibrium when the clearance is 0.4 mm ( = 0.4 mm). The inverted trapezoid rear wear ring exhibits the lowest leakage, averaging a 15.97% reduction across flow rates. Changes to the rear wear ring clearance structure are found to reduce leakage and rear pump chamber pressure while slightly improving efficiency. Adjusting the balance hole diameter reduces the leakage backflow interference on the impeller internal flow and promotes the vortex structure development within the balance hole. Changes to radial position of the balance hole effectively reduce leakage. When balance holes radial position is 59 mm ( = 59 mm), the vortex structure can be utilized to control impact of leakage flow on the mainstream within impeller. This paper provides certain theoretical reference for the design, optimization, and application of canned motor pumps.