Effect of inclination angles and upper end conditions on the countercurrent flow limitation in straight circular pipes

Abstract In the present study, the experimental data of the countercurrent flow limitation (CCFL) for air and water in inclined pipes are investigated. Water is introduced at the top of the test section while air is injected at the bottom as countercurrent flow. The water flow rate is fixed while the air flow rate is slowly increased, until the CCFL is reached. Data from each experiment consists of the flow rates of air and water. The curves of CCFL are built and shown as a function of the dimensionless superficial velocity. The influence of the inclination angles of the pipes and upper end conditions on CCFL are also discussed.