Recognition and measurement in the flow pattern and void fraction of gas–liquid two-phase flow in vertical upward pipes using the gamma densitometer

An experiment has recently been carried out to recognize the flow pattern and to measure the void fraction of gas–liquid two-phase flow in vertical upward pipes at Xiʹan Jiaotong University (XJTU). The test fluid in this experiment is the air and water. The experimental system includes a closed water loop, an open air loop, inlet and outlet header, vertical upward parallel pipes, a high speed camera system and a gamma densitometer system. The inlet header, outlet header and vertical upward pipes are made of transparent glass and acrylic fabric, and the purpose is for bubbly flow, slug flow and annular flow patterns visualization. In this present study, firstly, the flow patterns of the two-phase flow are identified by the high speed camera system and gamma densitometer system. Secondly, the void fraction of the two-phase flow is measured by the gamma densitometer, and the results are compared with the quick-closing valve measurement. Thirdly, the variations of the flow patterns with the void fraction are also discussed in the present study. Finally, the experimental results in present study are compared with some calculated (predicted) correlations.