The purpose of this paper is to investigate the performance improvement mechanism of a high power vertical centrifugal pump by using numerical calculations. Therefore, a comparative study of energy losses and internal flow characteristics in the original and optimized models was carried out with special attention to the hydraulic component matching. The optimized model (model B) was obtained by optimizing the vaned diffuser and volute based on the original model (model A), mainly the diffuser inlet diameter, diffuser inlet vane angle, volute channel inlet width and volute throat area were changed. Firstly, the comparative results on performance and energy losses of two models showed that the efficiency and head of model B was significantly increased under design and part-load conditions. It is mainly due to the dramatic reduction of energy loss P_L in the diffuser and volute. Then, the comparisons of P_L and flow patterns in the vaned diffuser showed that the matching optimization between the model B impeller outlet flow angle and diffuser inlet vane angle resulted in a better flow pattern in both the circumferential and axial directions of the diffuser, which leads to the P_L3 reduction. The meridian velocity V_m of model B was significantly increased at diffuser inlet regions and resulted in improvements of flow patterns at diffuser middle and outlet regions as well as pressure expansion capacity. Finally, the comparisons of P_L and flow characteristics in the volute showed that the turbulence loss reduction in the model B volute was due to the flow pattern improvement at diffuser outlet regions which provided better flow conditions at volute inlet regions. The matching optimization between the diffuser and volute significantly reduced the turbulence loss in volute sections 1–4 and enhanced the pressure expansion capacity in sections 8–10.

本文的目的是通过数值计算研究大功率立式离心泵的性能改进机理。因此，对原始模型和优化模型的能量损失和内部流动特性进行了比较研究，特别关注液压元件的匹配。优化模型（模型B）是在原模型（模型A）的基础上对叶片扩压器和蜗壳进行优化得到的，主要改变扩压器入口直径、扩压器入口叶片角度、蜗壳流道入口宽度和蜗壳喉部面积。首先，两种模型的性能和能量损失对比结果表明，模型B在设计和部分负荷工况下的效率和扬程均得到显着提高。主要是由于能量损失大幅减少P _L位于扩压器和蜗壳中。然后，通过PL和叶片扩压器内流型的比较表明，B型叶轮出口流角与扩压器入口叶片角的匹配优化使得扩压器周向和轴向上的流型均较好_，导致P _L3减少。模型B的子午线速度V _m在扩压器入口区域显着增加，从而改善了扩压器中部和出口区域的流型以及压力膨胀能力。最后， PL_的比较蜗壳中的流动特性表明，模型 B 蜗壳中湍流损失的减少是由于扩压器出口区域的流型改进，这为蜗壳入口区域提供了更好的流动条件。扩压器与蜗壳的匹配优化显着降低了蜗壳1~4段的湍流损失，增强了8~10段的压力膨胀能力。