Document Type : Article
Center of Excellence in Design and Optimization of Energy Systems School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
In this paper, an experimental study on the flow patterns of two-phase air-light oil flow is performed in a 20 mm diameter pipe with a length of 6 m in different orientations with pipe angles in the range of -45 to +45. The flow regimes are captured by a high speed camera. In the experiments, the air with the viscosity of 0.019 mPa.s and the density of 1.2 Kg/m3 and a light oil with the viscosity of 2.6 mPa.s and the density of 840 Kg/m3 are used. During the experiments, different flow patterns are observed such as bubbly, slug, smooth stratified, wavy stratified, and annular flows. Flow regimes in different pipe inclination angles are inspected in two-phase air-light oil flow and flow pattern maps are proposed for every pipe inclination angle. In addition, a comprehensive study on major forces acted on dispersed phase are presented theoretically to perform a thorough discussion on effects of pipe inclination angle on transition boundaries between flow patterns in two-phase air-light oil flow. It is inferred that non-stratified flows are dominant flow patterns in the upward flows and stratified flows are dominant flow patterns in the downward flows.