Hysteresis effects in countercurrent gas‐liquid flow limitations in a vertical tube

New experiments on air‐water countercurrent flow limitations in a vertical pipe are presented. The experiments were carried out to investigate the effect of test procedure on the occurrence of the two countercurrent flow limitations; namely the onset of flooding and complete carry‐up limits. The results revealed the existence of significant hysteresis effects at both limits particularly for high liquid feed rate. For low liquid feed rate, hysteresis effects were only observed at the complete carry‐up limit. Some associated visual observations are reported and the results were empirically correlated and compared with recent data obtained by others.