Transient Behavior of a Gas Slug : 2nd Report, On the liquid film thickness around a gas slug

Abstract

The transient phenomena induced in the case where a gas slug grows rapidly due to a very high evaporation rate of liquid or a drastic decrease of system pressure, were simulated by using an air-water flow system and experimentally investigated with special attention paid to the dynamic behavior of liquid film around a gas slug. Meanwhile a theory was proposed to express the thinning process of liquid film around a gas slug in a transient motion. As a result the following were made clear : When the film thickness is measured at a fixed point on a pipe wall, it decreases with time in both the cases of transient and steady flows. But the greater the growing rate of gas slug, the greater the decreasing rate of film thickness. The transient behavior of the film thickness can be predicted by the proposed theory with a sufficient accuracy.