THEORETICAL AND EXPERIMENTAL INVESTIGATION OF THE ONSET OF SLUGGING IN HORIZONTAL STRATIFIED AIR-WATER COUNTERCURRENT-FLOW

An experimental and theoretical study has been carried out to derive t he wave height and transition criterion from wavy to slug flow in hori zontal air-water countercurrent stratified flow conditions. A theoreti cal formula for the wave height in a stratified wavy flow regime has b een developed using the concept of total energy balance over a wave cr est to consider the shear stress acting on the interface of two fluids . From the limiting condition of the formula for the wave height, a cr iterion for transition from a stratified wavy flow to a slug flow has been derived. A series of experiments have also been conducted changin g the non-dimensional water depth and the flow rates of air in a horiz ontal pipe and a duct. Comparisons between the measured data and the p redictions of the present theory show that the agreement is within +/- 1O%.