The effects of surface tension on the flow pattern and counter-current flow limitation (CCFL) in gas-liquid two-phase flow in an inclined pipe

The experiment was conducted in order to determine the effect of surface tension on the flow pattern and counter-current flow limitation (CCFL) in counter-current gas-liquid two-phase flow in an inclined pipe, 16 mm in inner diameter and 5.5 m in length. The pipe inclination angles examined were 30deg, 45deg and 60deg from horizontal. Three different liquids, including water and aqueous oleic acid natrium solution, were employed. The surface tension of these liquids varied from 0.072 N/m to 0.034 N/m. The flow patterns were determined using a video recorder as well as the time variation of liquid hold-up. It was found that the flow pattern transition and CCFL strongly depended on the liquid surface tension and the pipe inclination. The effect of liquid surface tension on the flow pattern and interfacial structures were discussed. Furthermore, the flow pattern maps for each liquid surface tension inclination were proposed. Finally, the Weber numbers as the system parameters were evaluated. (author)