Experimental study of the factors affecting the flow pattern transition in horizontal oil-water flow

Flow patterns are important for pressure gradient calculation and corrosion protection. In this study, the characteristics of oil-water flow were investigated in a horizontal acrylic pipe with an inner diameter of 14.6 mm. The effects of oil viscosity, pipe diameter, pipe material and oil type were studied. Mineral oils with viscosity values of 20, 237 and 456 mPa.s were used as the working fluids. The flow patterns were identified by a high-speed camera and pressure gradients. The size of the dispersed oil droplets increased with increasing oil viscosity. The mixture velocity required to initiate ST&MI flow from SS flow increased with increasing oil viscosity. The transition boundaries extended to high velocities with increasing pipe diameter. In large-diameter pipes, the low-viscosity oil-water flow patterns were stratified flow, dispersed flow and their transition flow, and the high-viscosity oil-water flow patterns were annular flow in addition to these other flows. In small-diameter pipes, stratified flow, dispersed flow, annular flow and intermittent flow patterns were found for both low- and high-viscosity oil-water flow.