Experimental investigation of oil–water two phase flow regime in an inclined pipe

• The effect of inclination angle has been considered on the flow regime.
• Flow pattern maps are proposed for inclination angles in the range of −45–45.
• The transition boundary has been considered in downward and upward flow.
• Obtained flow maps have been compared with other available experimental data.

The flow pattern in two-phase flows is a significant factor which influences many other parameters such as heat transfer and pressure drop in pipelines. In the present work, flow patterns of two-phase oil–water flow is investigated experimentally in a 20 mm diameter pipe with a length of 6 m. A high speed digital camera has been equipped for visualization, flow regime identification and flow recording. In this study acting forces on dispersed phase are discussed theoretically and flow patterns in different pipe inclination angles are investigated in two-phase oil–water flow. The range of inclinations has been varied between −45 and +45°. Flow pattern maps are investigated for every inclination angle of pipe and compared with other available experimental data. Finally, the effect of pipe inclination angle on transition boundaries between flow patterns is investigated comprehensively. Various flow patterns are seen; bubbly, slug, smooth stratified, wavy stratified, churn, annular and dual continuous flow. From the obtained results, it can be inferred that non-stratified flows such as bubbly and slug flows are dominant flow patterns in the upward flows and stratified flows are dominant flow patterns in the downward flows.