设平衡孔时气液混输泵内部流动及轴向力分析

本文采用两相混合模型进行数值模拟计算，探究了不同进口含气率条件下，设置平衡孔对气液混输泵外特性、内部流动及轴向力的影响。研究发现：各工况条件下，设置平衡孔后该混输泵的轴向力均明显减小；从平衡系统回流的高压流体对转轮内部流动状态产生扰动，同时能破坏和夹带转轮流道内聚集的气泡；综合考虑对混输泵的性能和轴向力的影响，在较低进口含气率时采用平衡孔方法平衡混输泵轴向力的方法是可行的；平衡系统进出口压力系数随比面积系数增大而非线性减小，平衡孔的直径过大会导致混输泵的容积损失问题，因此平衡孔直径设计存在最佳值；对比发现平衡孔设在转轮叶片吸力面时转轮的轴向力幅值和脉动相对较小。研究结论可为后期多级气液混输泵平衡孔平衡轴向力系统的设计和优化提供思路和借鉴。

Analysis of flows and axial forces in gas-liquid mixed pump with balance hole

This paper presented the numerical simulation of the two-phase flow in a gas-liquid mixed pump by applying a mixing model. The influence of setting balance holes on the internal flow, performance and axial force under different inlet gas holdups was examined. This study found that the runner axial force reduced significantly under various operating conditions after setting balance holes; high-pressure fluid flowing back from the balance system disturbed the internal flow state, and could destroy and entrain bubbles accumulated in the flow channels. Taking the influence on the performance and axial force into consideration, we found it feasible to balance the axial force by using the balance hole in case of low air content at inlet. The inlet and outlet pressure coefficients of the balance system decreased nonlinearly with the increase of specific area coefficient; an excessive hole diameter will lead to a loss of the pump’s effective volume. Therefore, the optimal diameter should be adopted in design. We further found the amplitude and pulsation of the axial force were relatively small when the balance holes were located on the suction surfaces of the runner blades. This study sheds light on the understanding of the multistage gas-liquid mixed pump modified with the balance hole and provides reference for the design and optimization of its axial force system.