Effect of different loading distribution forms on the energy characteristics of mixed-flow pumps

Loading distribution significantly affects the flow field in the impeller channel, but research on the effects of different loading distribution forms on the performance of mixed-flow pumps is relatively scarce. In this study, three typical mixed-flow pump models, namely front-loading model (FLM), middle-loading model (MLM), and back-loading model (BLM), were designed by changing the loading distribution at the shroud using the inverse design method. The energy losses within the three models were analyzed quantitatively and visually using the entropy generation method. The results show that using front-loading, middle-loading, and back-loading in the design of mixed-flow pumps improves efficiency under common, low, and high flow rate conditions, respectively; in particular, the efficiencies of the FLM, MLM, and BLM under design conditions were 88.72%, 87.82%, and 87.01%, respectively. The entropy generation analysis indicates that the loading distribution has a minor influence on the energy loss within the impeller, but its influence on the energy loss in the downstream components of the impeller can exceed 30%. Internal flow analysis shows that the effect of loading distribution on the relative velocity and adverse pressure gradient at the impeller outlet is the primary reason for the change in the performance of mixed-flow pumps.