Author(s): Qifan Deng; Ji Pei; Wenjie Wang; Shouqi Yuan

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Keywords: Impeller trimming; Double-suction centrifugal pump; Performance; Numerical simulation; Experimental validation

Abstract: In order to research the relationship between impeller trimming and performance in a double-suction centrifugal pump, impellers were trimmed 11 mm and 22 mm respectively. Numerical methods were applied combined with the original one, and experimental validation was also carried out on original and 11 mm model. The performance and difference of total pressure between volute inlet and outlet was calculated, meanwhile, distributions of velocity and turbulence eddy dissipation on volute middle section were analyzed. The results indicate that the head drops with the trimming process and discontinuity appears when trimmed 22 mm. The impeller trimmed 11 mm is the most efficient under part-load and design conditions, while the original model has the lowest efficiency. Efficiency in trimmed cases decreases dramatically under over-load condition, especially when trimmed 22 mm. Due to rotor-stator interaction between impeller and volute receded by the enlarged clearance, the head losses inside the volute decrease with impeller trimming but increase significantly under 1.4Qd when trimmed 22 mm. The extremely high shock losses resulting from exaggerated impeller outlet flow angle and dissipation near volute tongue account for it. Moreover, the losses in volute diffuser channel increase due to the vortexes generated by flow separation and backflow. The losses in volute will be improved by impeller trimming within reasonable limits in a double-suction pump. This research provides theoretical foundation for impeller trimming in double-suction centrifugal pumps.

DOI: https://doi.org/10.1088/1755-1315/627/1/012014

Year: 2019