中文摘要：

首先用Khabenskii方法预测了并联蒸发管内的两相流动不稳定边界，发现当出口为过热蒸汽时Khabenskii方法预测值与实验值有较大偏差，最高达80％。然后采用RELAP5／MOD3．4程序模拟垂直并联蒸发管道的流动工况，得到的流量脉动特性与实验值能较好地吻合，同时其预报的两相流不稳定边界也与实验结果很好吻合，误差在25％以内。最后用RELAP5／MOD3．4程序分析了质量流速、入口阻力、出口阻力、入口过冷度、入口压力等因素对并联直流蒸发管内两相流动不稳定性的影响。

英文摘要：

Two-phase flow instability boundary of two parallel evaporation tubes was predicted. When the outlet of the tube is superheated steam, obvious deviation exists between the prediction results using Khabenskii method and experimental results, the maximum deviation can reach 80%. The flow and heat transfer characteristic was also simulated using RELAP5/MOD3.4 code. The density wave oscillatory behavior and instability boundary predicted using RELAP5/MOD3.4 code agree well with experiment results, the maximum deviation was 25%. Based on these results, main operating parameters such as mass flow rate, inlet resistance factor, outlet resistance factor, inlet subcooling and inlet pressure were analyzed to study their influences on two-phase flow instability of vertical parallel evaporation tubes.