The influence of impeller eccentricity on centrifugal pump

In order to study the influence of the impeller eccentricity on the performance of centrifugal pump, the k-epsilon turbulence model was selected, and ANSYS CFX was provided for numerical simulation calculation of the centrifugal pump with impeller offsets of 0, 1, 3, and 5mm. The results show that with the impeller eccentricity increasing, the head and efficiency become lower. Under the condition of rated flow, with the impeller eccentricity increasing, the area of low pressure at the suction surface of the short blade inlet become smaller gradually; however, the area of low pressure at the suction surface of the long blade inlet become larger, and the pressure at the impeller inlet and tongue become larger too. The corresponding critical net positive suction head increases in turn, as means that the cavitation performance of the pump becomes worse gradually. The bubble volume fraction in the impeller increases with the decrease of the static pressure at the inlet. The bubble first occurs at the inlet of the blade suction surface, and then extends gradually to the channel and even the outlet. Near the rated flow, radial force on the impeller and volute decreases with the increasing of flow, and the radial force characteristic becomes worse gradually with the increasing of the eccentricity.