断电停机过渡过程中核主泵气液两相流动特性研究

为研究断电停机过渡过程中核主泵气液两相瞬态流动特性，借助CFD技术对不同含气量下核主泵内的气液两相流动变化规律及径向力进行了研究，并对计算结果进行试验验证。结果显示，数值模拟数据与试验数据变化趋势吻合，断电停机过渡过程中，在叶轮背面附近产生旋涡，旋涡的存在使气相区域变大且相应的气体体积分数增加。随着流量的减少和转速的降低，叶轮和导叶内存在大量的气相，导致叶轮转换能量的能力减弱。含气量较小时，叶轮内气体体积分数先达到最大值后开始呈离散状回旋下降。而含气量较大时，叶轮内的气体体积分数随流量的减少而增加。含气量对流道内流体的速度影响较大，尤其是对靠近叶片进口方向的流体。随着含气量的增加，叶轮的径向力不平衡程度开始减弱，其最大不平衡径向力由正负值不等转变为以负值为主。

Study on Flow Characteristics of Gas-liquid Two-phase for Reactor Coolant Pump With Power Shutting Down Transition Process

For the study of gas-liquid two-phase transient flow characteristics with the power shutting down transition process in the reactor coolant pump, with the help of CFD, the gas-liquid two-phase flow variation and radial force were researched by experimental verification at different gas contents and the calculation results were verified by experimental test. The results show that the numerical simulation data agree well with the test data and vortex near the back of the impeller is produced, which makes the gas-phase region become large and the corresponding gas volume fraction increases. The capacity of the impeller to convert energy reduces with the reductions of flow rate and rotation speed, which leads to a large number of gas-phase in the impeller and guide vanes. When the gas content is small, the gas volume fraction will reaches a maximum before it declines in rotating dispersed form. When gas content is large, the gas volume fraction in the impeller increases with the reduction of flow rate. Gas content has a great influence on speed in flow passage of the impeller, especially for that close to blade inlet. The unbalance of radial force begins to fall off with the increase of gas content, and its maximum unbalanced radial forces changes from imbalance region between positive and negative value to that of negative value prevailing.