(An) extension of the adiabatic interfacial friction factor correlation in countercurrent stratified two-phase flow

Abstract

Although the stratified flow pattern among all the two-phase flow patterns has been considered as the most simple one in horizontal or slightly inclined channels, some difficulties in its analysis arise from the interactions between the gas and liquid flows and the waves. In addition, there are still some competing results among the previous works on countercurrent stratified flow, particularly, involving the prediction of the interfacial friction factor which is needed in the analysis of two-phase flow phenomena. And the effect of the inclination angle on the interfacial friction factor has been rarely studied until recently. It is necessary, therefore, to develop an interfacial friction factor correlation applicable to the countercurrent flow in order to obtain reliable results. In the present study, interfacial flow behaviors for the countercurrent stratified air-water flow have been experimentally investigated in nearly horizontal and inclined pipes. Using the gas momentum equation, the data for interfacial friction factor have also been obtained from the measurements of air and water flow rates, liquid level, and pressure drop. For a fixed water flow rate with no air flow, the hydraulic jump with two distinct water levels was present in a nearly horizontal pipe. In slightly inclined pipe (1o and 2o), on the other hand, the hydraulic jump occurred near the water outlet for a high air flow rate. The presence of the hydraulic jump may significantly affect on both the flow pattern and the interfacial friction factor. The measured values of the interfacial friction factor in nearly horizontal and two inclined pipe tests were the same order of magnitude but the dependencies of the air and water velocities were slightly different. Semi-empirical correlations to predict the interfacial friction factor for nearly horizontal and slightly inclined pipe conditions have also been developed for the stratified-wavy flow. In the present study, the correlations for nearl...