Influence of Splitter Blades on Energy Loss Redistribution and Flow Mechanisms in a Double-Suction Pump as Turbine

Abstract

To clarify the effects of splitter blades on hydraulic performance and internal energy dissipation in a double-suction pump as turbine (PAT), full-passage CFD models of a PAT and a PAT with splitter blades were established and experimentally validated. Same-flow-rate cross-comparisons at the BEP flow rates of the configurations distinguished geometric effects from flow-rate effects. Impeller loss redistribution was analyzed using entropy generation, LEGR, TKE, and radial-flow characteristics. The splitter blades shifted the BEP flow rate from 1350 to 1708 m3/h, an increase of 26.52%, and increased the maximum efficiency from 85.61% to 87.72%. Turbulent and wall entropy generation dominated the loss, whereas direct viscous entropy generation contributed less than 1%. At the prototype BEP flow rate, the normalized volumetric entropy-generation coefficient over Regions I–O decreased by 10.31%; at the splitter-blade BEP flow rate, the reduction reached 60.71%, with Region M decreasing by 66.33% and providing the dominant absolute loss reduction. At the higher flow rate, splitter blades restricted the lateral expansion of low-velocity regions, weakened large-scale separation and continuous high-LEGR shear structures, and confined the remaining high-loss regions to blade leading edges, splitter-blade wakes, and local flow-recombination zones. These results show that splitter blades improve high-flow-rate performance by suppressing separation- and shear-related volumetric dissipation and redistributing impeller energy losses.