管径对垂直上升管内气液两相流流型的影响

Effect of tube size on flow pattern of air-water two-phase flow in vertical tubes

以空气和水作为介质,在管径分别为20 mm与8 mm的垂直上升管内进行了常压下气液两相流流型的实验研究,得到了这两种管径下泡状流、弹状流、乳状流和环状流等流型,得到的绝大部分实验点与Hewitt和Roberts流型图相符合,并根据实验结果修正了流型图的转化边界。对于气液两相流垂直上升流动,环状流发生所需的气相折算速度几乎不随液相折算速度的变化而变化。不同管径条件下,各种气液两相流流型发生的范围和转换趋势基本一致,乳状流向环状流的转换界限基本重叠,而泡状流与弹状流的界限变化大一些。由于弹状流的换热与泡状流的换热完全相同,因此泡状流与弹状流的界限误差对传热而言并不重要,可以忽略管径对Hewitt和Roberts流型图的影响。

The air-water two phase flow pattern in vertical tube was experimentally investigated with different tube inner diameter of 20 mm and 8 mm under atmosphere condition.The bubbly flow,slug flow,annular flow and mist flow are observed for two size tubes.Most of the experimental points agree well with Hewitt and Roberts flow pattern map when putting them on the map.With the experimental results,the range line between the flow patterns is suggested for the tubes of 20 mm inner diameter as well as 8 mm.For the vertical flow up,the air superficial velocity when the annular flow appears is independent of the water superficial velocity.The two phase flow patterns range line is similar in tendency and scope for different tubes.The range line between mist flow and annular flow for different tubes is almost overlapping while that between bubbly flow and slug flow is inconsistent for different tubes.The confusion error between bubbly flow and slug flow is of no great importance for heat transfer because the heat transfer for bubbly flow or for slug flow is same.It is believed that the effect of the tube diameter on the two-phase flow in vertical tubes could be neglected,and the Hewitt and Roberts flow pattern map could be adopted without any consideration of tube diameter.