Experimental study of horizontal two- and three-phase flow characteristics at low to medium liquid loading conditions

An experimental study is conducted using a 0.075-m ID pipe to investigate characteristics of two- and three-phase stratified flow in a horizontal pipeline. Experiments are conducted under low to medium liquid loading conditions which is common in wet-gas and long transportation pipelines. The flow characteristics investigated include flow pattern, liquid holdup and pressure drop. The experimental range covers superficial gas Reynolds numbers from 6314 to 200,734, superficial liquid Reynolds numbers from 160 to 4391 and water-cut values from 0 to 90%. Differential pressure transducers, quick closing valves and a high-speed camera are utilized to obtain the relevant data and the trends investigated. The observed flow patterns are stratified smooth, stratified wavy and stratified-annular flow. The transitions between flow patterns vary as a function of water-cut. The effect of water-cut on liquid holdup and pressure drop were relatively negligible especially at low water-cut conditions and the fine mixing of the oil-water mixture may be partially responsible for this. As a result, with the exception of flow pattern transitions, the performances of classical two-phase flow models (for the prediction of liquid holdup and pressure drop) appear unaffected when applied to air–oil–water 3-phase flows especially at high water-cuts.