Analysis of Internal Leakage in Multistage Centrifugal Pumps under Conditions of Impeller Oscillation and Non-oscillation

Abstract Centrifugal pumps with multiple stages and floating impellers provide a convenient option for easy adjustment, boasting advantages such as easy head adjustment and efficient transfer of axial thrust from the impeller to the casing. These pumps utilize sealing gaskets to reduce leakage and control the axial movement of the impeller. Nonetheless, the influence of impeller oscillation and non-oscillation conditions on leakage losses and internal flow characteristics remains uncertain. To explore these phenomena, numerical simulation methods were employed, enabling the impeller to undergo both axial movement and rotation, with validation achieved through experimental verification of the numerical simulation results. Leakage in the front pump chamber exceeded that of the rear pump chamber significantly, whether oscillation was present or not. Consequently, the impeller’s immediate position during oscillation had a more pronounced impact on leakage in the front pump chamber than in the rear pump chamber. The overall leakage trend in the front pump chamber exhibited a negative correlation with the impeller’s instantaneous position, whereas it displayed a positive correlation with the overall leakage trend in the rear pump chamber. Impeller oscillation notably impacted the flow velocity and pressure in the front pump chamber, while exerting minimal effects on those parameters in the rear pump chamber. This research offers valuable insights on improving the efficiency and stability of multistage pumps.