Influence of internal flow structure on flow energy losses in a centrifugal pump with splitter blades using entropy generation theory

Centrifugal pumps are essential in various industrial applications, including renewable energy. To maximize the pump's overall performance, estimating flow energy losses (FEL) is crucial. However, due to internal flow complexity, it is necessary to employ new methods and approaches to better understand FEL mechanisms. This study uses entropy generation theory to investigate the relationship between FEL and various flow patterns in all pump hydraulic components. Numerical simulations were conducted using a 3-dimensional incompressible unsteady flow at four different flow coefficients. The delayed detached eddy simulation (DDES) model was used, and the results showed good agreement with experimental data compared to the SST k-w model. Emphasis was given to the flow energy losses and the relative and absolute velocity distribution in the impeller and diffuser components at various flow coefficients. Flow energy losses primarily occur in the impeller (70%) followed by the diffuser (23%). Impeller losses are concentrated at the outlet region due to the wake-jet phenomena (28.6%), splitter blades region (15.3%), and impeller's leading edge (LE) (10.7%). Vaned diffuser losses occur in the vanless zone (stator-rotor interaction) and near leading/trailing edges. Moreover, wall shear stress and the significant relative velocity gradient near the walls of the impeller and diffuser blades are the main contributors to the FEL in this region. This study provides insights into a better understanding of FEL mechanisms and highlights areas for improving pump performance.