Experimental study on the liquid holdup characteristics of air-water horizontal stratified flow by using an image processing technique

Understanding of the characteristics of stratified two-phase flow pattern in horizontal pipeline is a challenging problem relevant in many processes of chemical, nuclear and petroleum industries. One of the most important parameter to study the flow characteristics of two-phase flow is the liquid holdup, defined as the cross sectional area occupied by the liquid phase divided by the cross sectional area of the inner pipe. Those complex behaviors had been studied by numerous researchers, a lot of mathematical models had been proposed to figure-out the phenomena. Meanwhile, there were some discrepancies among each other. Hence, the validation is needed to get a better understanding of it. From the fact, an experimental study of stratified two-phase flow pattern had been conducted in a 26 mm i.d. horizontal transparent acrylic pipe with emphasis on the study of liquid holdup. Air and water were used as the test fluids, flowing concurrently inside the pipe. The flow behavior was recorded by using a high speed-video camera and digital image processing technique was used to perform the quantitative analysis of the captured video data. The group of stratified smooth and wavy two-phase flows was successfully recorded and classified based on the visualization study from 24 couples of test condition of water and air superficial velocities. From these results, the behavior of stratified two-phase flow was discussed and used to evaluate the existing data and correlations.