Prediction of flooding gas velocity in gas–liquid counter-current two-phase flow in inclined pipes

The purpose of the experimental study is to investigate the effects of pipe inclination, pipe length, pipe diameter and surface tension of the working liquid on the onset of flooding of gas–liquid adiabatic counter-current two-phase flow in inclined pipes. Flooding in inclined pipes were observed by using the combination of visual observation, measurement of discharged liquid flow rate and time variation of liquid hold-up. And it was defined as the maximum air flow rate at which the discharged liquid flow rate is equal to the inlet liquid flow rate. As a result we proposed a correlation to predict the flooding gas velocity in inclined pipes under a given liquid flow rate, and the predictions agreed well with the experimental observations.