矩形通道内泡状流-弹状流转变判定准则研究

Study on Transition Criterion from Bubble Flow to Slug Flow in Rectangular Channels

以空气和去离子水为工质，对竖直矩形通道内两相流流型特性进行实验研究；矩形通道的横截面为1．41mm×40mm和10mm×40mm，实验压力为常压，气、液相表观速度分别为0．015--0．59m／s和0．025-3．74m／s。利用获得的实验数据及文献数据，对4种典型泡状流．弹状流转变判定准则进行评价，结果表明4种准则都存在一定局限性。从实验数据及文献数据可以看出，泡状流．弹状流转变临界空泡份额为通道窄边与宽边比（宽高比s／w）的函数。为此，以当量直径10mm为界，分别提出临界空泡份额计算关系式，从而得到修正转变判定准则。与本文及文献中实验数据的比较，修正准则较4种典型准则精度和适用性有一定提高。

Using air and deionized water as working fluids, flow pattern characteristics of two-phase flow was investigated experimentally for two vertical rectangular channels with the cross sections of 1.41×40mm2 and 10×40mm2. Experiment was conducted under atmospheric condition, and the superficial velocities of air and water were in the ranges of 0.015-0.59rn/s and 0.025-3.74m/s. Four classical transition criteria from bubbly flow to slug flow are evaluated against present experimental data and that from open literatures. The result shows that the four transition criteria are limited to some extent. Through the analysis of the dataset, it is found that aspect ratio is a key parameter to determine the critical transition void fraction, for which two correlations are given according to the threshold of 10mm of the hydraulic diameter. As a result, the modified criterion is obtained and is satisfactory agreement with the present data and the existing experimental data, and it is better than four classical transition criteria.