Fluid structure interaction induced fatigue stress analysis of multi-stage centrifugal water pump shaft under varying load condition

Abstract The centrifugal pump shaft provides support to rotating parts and transmits power to the rotating components such as impeller of the pump. During pumping operation, the pump shaft is subjected to a range of loads including cyclic flexural and torsional loads. This study aims to examine the multi-stage centrifugal water pump shaft’s fatigue performance under varying load conditions. To achieve the objective, numerical and analytical fatigue structural analysis of a shaft in a three-stage centrifugal pump was performed. The fatigue performance was analyzed using the computational fluid dynamics module of ANSYS 19.0 CFX, and the pressure distribution at various flow conditions ranging from 0.6 to 1.4 of the design flow rates were obtained. The fatigue performance was analyzed both without fluid pressure and by employing one-way fluid structural interaction analysis, resulting in von Misses stress of 122.6 MPa and 137.58 MPa, respectively, while the simulated minimum safety factor is 1.67. The findings show that the fluid pressure at different flow rates cause high stress and deformation of the shaft. The analytical and numerical fatigue analysis results are in good agreement.