Investigation on the effect of diffuser vane load slope on the energy dissipation and periodic unsteadiness in centrifugal pump

To ensure the long-term efficiency and stability of large volute-type centrifugal pumps, the impact of different guide vane load distributions on pump performance and internal flow conditions is analyzed. A three-dimensional inverse design method combined with computational fluid dynamics technology is adopted. Nine load distribution schemes are developed, based on the slope values in the load distribution curve. These schemes highlight the strong correlation between the slope of the load distribution curves at the shroud and hub and the pump's efficiency and head. This study examines the pressure distribution, energy loss, and pressure pulsation characteristics of the nine load distribution schemes. It is found that the front-loaded scheme at both the shroud and hub (Scheme A-A) consistently exhibits poor pressure distribution. In this scheme, the pressure at the guide vane inlet is greater than at the outlet, significantly reducing the pump's head. Both the front-loaded (Scheme A-A) and rear-loaded (Scheme C-C) shroud and hub configurations show large regions of entropy production. In Scheme C-C, the hydraulic loss at the guide vane reaches 0.59 m. The combination of a front-loaded shroud and a rear-loaded hub (Scheme A-C) as well as the mid-loaded shroud and hub configuration (Scheme B-B) minimizes energy loss within the passage and improves hydraulic performance. As the flow rate increases, high-pressure pulsation regions expand. In the front-loaded scheme, these regions become more pronounced. However, the rear-loaded scheme (e.g., Scheme C-C) effectively suppresses pressure pulsations in the leafless region. This configuration reduces the pulsation amplitude by 32.7% compared to the front-loaded scheme at 1.1Qd.