Influence of Inflow Conditions on Parameter Analysis and Optimization Results of Mixed-Flow Pumps

Conventional mixed-flow pump designs are typically developed under the assumption of uniform inflow. However, due to various operational constraints, these pumps often operate under non-uniform inflow conditions, which can significantly deteriorate hydraulic performance and operational stability. To investigate the influence of inflow conditions on parameter analysis and optimization results of mixed-flow pumps, this study conducted optimization design under both uniform and non-uniform inflow conditions. Four loading control parameters—LE (leading-edge preloading), K (slope of the intermediate linear segment), and NC and ND (first and second loading inflection positions)—were selected as design parameters, while the weighted hydraulic efficiency at 0.8Qdes, 1.0Qdes, and 1.2Qdes served as the optimization objective. Under uniform inflow conditions, the sensitivity ranking of the parameters for efficiency (subscripts s and h denote shroud and hub, respectively) is: LEs > Kh > LEh > NDh > NCh > Ks > NCs > NDs. The corresponding optimal parameter values are −0.2, 0, 0.2, 0.4, 0.25, 1.5, 0.1, and 0.6. Under non-uniform inflow, the ranking changes markedly to: NCh > LEs > Kh > Ks > NDh> LEh > NDs > NCs, with optimal values of 0.4, 0, 1.5, 0, 0.6, −0.2, 0.8, and 0.1, respectively. Compared with the baseline model, the optimized configurations achieve efficiency improvements of 0.61%, 2.94%, and 3.74% under uniform inflow, and 0.23%, 4.42%, and 6.78% under non-uniform inflow. Analysis of the internal flow field indicates that incorporating inflow conditions at the initial design stage significantly enhances the robustness of the optimized blade geometry when subjected to non-uniform inflow. These findings provide important implications for the optimization and practical design of mixed-flow pumps operating under complex inflow environments.