气液界面摩擦因子对分层流向段塞流过渡的影响

根据气液两相流段塞稳定性理论,结合分层流理想化模型,对直径2.54 cm水平管内空气-水两相流出现段塞流时的各相临界表观速度和临界液层高度进行了理论预测,并且分析了气液两相界面的摩擦因子对于预测流型转变的影响.由于在不同的气相流速范围内,段塞流由不同形式的界面波形成,当气相表观速度小于 4 m(s(1时,由大振幅波形成段塞流,而当气相表观速度大于 4 m(s(1,段塞流由小波长的滚动波合并而成,因而根据实测数据对界面摩擦因子的计算进行了补充修正,并且应用到对应的气相流速范围.基于所给出的计算方法解得发生分层流向段塞流转变的临界表观速度和临界液层高度,并和实验数据进行了比较. 结果表明所做的修正可以避免以往理论预测中出现的低估情况,求得的各临界特征参数值和实验结果吻合得较好.

The Influence of Gas-Liquid Interfacial Friction Factor on the Transition from Stratified to Slug Flow

Based on the slug stability model and simplified stratified flow model, the predictions of the critical liquid heights and critical superficial velocities for the transition of a stratified flow to a slug flow in a horizontal 2.54 cm pipe was provided. The influence of the variation in gas-liquid interfacial friction factor on the prediction of flow regime transition was analyzed. It is found that the slug flow derives from different interfacial wave patterns, such as when the superficial gas velocity is less than 4 m?s?1, the slugs evolve from large amplitude waves, while when the superficial gas velocity is higher than 4 m?s?1, the slugs arise by the coalescence of small wavelength roll waves. The underestimated gas-liquid interfacial friction factor will cause the discrepancy between theoretical prediction and experimental data. Based on the measured results, the modified correlations of the interfacial friction factor for different superficial gas velocities were presented separately, and the corresponding calculations were conducted. The results show that with the modified interfacial friction factors, the slug stability model gives a reasonable prediction at higher gas flow rates, and better agreement between predicted and measured critical parameters can be achieved.