Influence of Axial Matching between Inducer and Impeller on Energy Loss in High-Speed Centrifugal Pump

Studying the axial matching between the inducer and impeller is crucial for optimizing the structure of centrifugal pumps. In this paper, the SST k-ω turbulence model is used to analyze the influence of three axial positions on the internal flow and the energy loss of a centrifugal pump. Additionally, the entropy generation method is used to evaluate the energy loss in the pump. Three sets of inducer design schemes are selected based on the ratio of the distance from the trailing edge of the inducer to the impeller inlet and the impeller inlet diameter, which are λ = 0.6, λ = 0.9 (original scheme), and λ = 1.2, respectively. The results indicate that changing the axial position of the inducer between λ = 0.6 and λ = 1.2 has only a negligible effect on the overall performance of the centrifugal pump. At flow rates of 0.6Qd and 1.0Qd, the inlet pressure coefficient of λ2 is significantly lower compared to λ1 and λ3. As the flow rate increases, the pressure coefficient difference between the inlet and outlet in the inducer decreases, which leads to a more uniform streamline distribution and better development of the vortex in the flow channel. The energy loss in the inducer mainly occurs at the rim, the trailing edge, and outlet near the wall. As the flow rate increases, the entropy generation rate at the inducer rim decreases slightly and remains around 1000 W·m−3·K−1. At flow rates of 1.0Qd and 1.2Qd, the energy loss in the impeller reduces as the axial distance increases, with the exception of the flow rate 0.6Qd.