In order to study the effect of different numbers of impeller blades on the performance of mixed-flow pump “saddle zone”, the external characteristic test and numerical simulation of mixed-flow pumps with three different impeller blade numbers were carried out. Based on high-precision numerical prediction, the internal flow field and tip leakage flow field of mixed flow pump under design conditions and stall conditions are investigated. By studying the vorticity transport in the stall flow field, the specific location of the high loss area inside the mixed flow pump impeller with different numbers of blades is located. The research results show that the increase in the number of impeller blades improve the pump head and efficiency under design conditions. Compared to the 4-blade impeller, the head and efficiency of the 5-blade impeller are increased by 5.4% and 21.9% respectively. However, the increase in the number of blades also leads to the widening of the “saddle area” of the mixed-flow pump, which leads to the early occurrence of stall and increases the instability of the mixed-flow pump. As the mixed-flow pump enters the stall condition, the inlet of the mixed-flow pump has a spiral swirl structure near the end wall for different blade numbers, but the depth and range of the swirling flow are different due to the change in the number of blades. At the same time, the change in the number of blades also makes the flow angle at 75% span change significantly, but the flow angle at 95% span is not much different because the tip leakage flow recirculates at the leading edge. Through the analysis of the vorticity transport results in the impeller with different numbers of blades, it is found that the reasons for the increase in the values of the vorticity transport in the stall condition are mainly impacted by the swirl flow at the impeller inlet, the tip leakage flow at the leading edge and the increased unsteady flow structures.

为研究不同叶轮叶片数对混流泵“鞍区”性能的影响，对三种不同叶轮叶片数的混流泵进行了外特性试验和数值模拟。在高精度数值预测的基础上，研究了混流泵在设计工况和失速工况下的内部流场和叶尖泄漏流场。通过研究失速流场中的涡量输运，定位了不同叶片数的混流泵叶轮内部高损失区的具体位置。研究结果表明，叶轮叶片数量的增加提高了设计工况下的泵扬程和效率。与四叶叶轮相比，五叶叶轮扬程和效率分别提高5.4%和21.9%。但是，叶片数量的增加也导致混流泵“鞍座区”变宽，导致过早发生堵转，增加了混流泵的不稳定性。随着混流泵进入失速状态，对于不同的叶片数，混流泵的入口在端壁附近具有螺旋涡流结构，但由于涡流的变化，涡流的深度和范围有所不同。刀片数量。同时，叶片数量的变化也使得75%跨度时的流角变化明显，但95%跨度时的流角差别不大，因为叶尖泄漏流在前缘再循环。