【摘要】 在西安交通大学高压汽水实验台架上进行了破口型式为渐缩渐扩喷嘴的临界流实验，实验参数为：入口压力３，０～１６．ＯＭＰａ，入口欠热度０～６０°Ｃ。对应临界质量流速为４０～１２０×１０３ｋｇ／ｍ２ｓ。实验表明，闪蒸起始点处的热力非平衡性随入口欠热度的增加而减小，入口为饱和状态时热力非平衡性最大。提出了一个新的空穴核化模型来预测闪蒸起始点处的减压值。该模型中含有一个由实验确定的系数，并被实验证实，该系数仅为入口欠热度的函数。将该模型计算的临界流量与临界流量的实验值进行了比较，取得了满意的结果。更多还原

【Abstract】 The transient critical flow experiment with convergent-divergent nozzleas as the break geometry was conducted in high pressure steam-water test loop Of Xi’an Jiaotong University. The test parameters are as follows: pressure 3.0～16.OMPa, inlet liquid subcooling 0～60°C,corresponding critical mass flow rate 40～120 ×103kg/m2s.The flashing incipient and the choking plane were assumed to occur at the throat(minimum)section. The total pressure difference between inlet pressure and pressure at throat location Was divided into two parts, one part only determined by the inlet fluid properties, the other being the pressure undershoot.The problem of computing critical mass flow rate is to find the pressure undershoot at choking plane. Our experimental results show that the pressure undershoot and the liquid superheat at the choking plane attain maximum values with saturated inlet condition.With increasing the inlet liquid subcooling,the thermal nonequilibrium is decreased.A new wall surface cavity nucleation model was developed for prediction of the pressure undershoot.The model includes a coefficient, and it is verified by the experiment that such coefficient is only the function of inlet liquid subcooling.Based on the present theory,the predicted critical mass flow rates agree well with the experimental data.更多还原