气液两相条件下离心泵内部流态及受力分析

为研究离心泵在气液两相条件下叶轮内部流态及受力情况,选取一比转数n_s=129的离心泵为研究对象,基于CFX软件提供的Eulerian-Eulerian非均相流模型对泵内部流场进行三维瞬态数值模拟,得到不同初始气相体积分数下叶轮流道内气相体积分数分布及叶片载荷等物理量变化规律,并将数值模拟结果与试验结果进行对比验证.结果表明:叶轮内气体主要集中分布在叶片吸力面区域,出口处则集中分布在流道中间区域,叶轮前盖板区域气相体积分数大于后盖板区域;当初始气相体积分数逐渐增大时,叶轮流道内流动紊乱,气液两相流动的不均匀性加剧,旋涡区域增大;随着初始气相体积分数的增大,叶片进口到靠近出口位置,叶片压力面所受压力载荷相对于吸力面减小的更快,而在出口位置附近叶片吸力面压力载荷减小的更快,叶轮径向力的不平衡性加剧,叶轮所受转矩减小.数值计算结果与试验结果在趋势上趋于一致.

Unsteady internal flow and thrust analysis of centrifugal pump under gas-liquid two-phase flow conditions

In order to study internal flow patterns and thrust on an impeller under gas-liquid two-phase flow conditions, a centrifugal pump with a specific speed of 129 is selected, and the unsteady three-dimensional flow in th pump is simulated by employing the Eulerian-Eulerian inhomogeneous multiphase flow model based on ANSYS CFX software. The variations of a few fluid flow variables such as pressure loading on blades, gas volume fraction distribution etc are obtained under different gas volume fractions admitted at the pump inlet, the predted head and efficiency are compared with the measured data. The results show that the gas phase is mainly accumlated on the blade suction surface and in the middle part of flow passage at the impeller outlet, further the gas volume fraction on the shroud are higher than on the hub. With increasing gas volume fraction at the pump inlet the flow disortion in the impeller passages becomes severe, henece the flow inhomogeneity between the gas phase and the liquid phase is intensified, and the vortex area is enlarged. From the inlet to the outlet of impeller, the pressure loading on the blade pressure surface reduces faster than on the blade suction surface, but the loading on the suction surface declines quicker near the impeller outle. The imbalance of the radial thurst on the impeller gets worse, and the torque acted on it decreases. 