Experimental study on highly viscous oil-water annular flow in a horizontal pipe with 90 elbow

The present study conducts an experiment on water lubricated oil-water flow inside a horizontal pipe designed with a 90 degrees elbow, in which the selected test fluids are mineral oil and tap water with a viscosity ratio of approximately 1000 and density ratio of 0.9. Measurements are recorded for the flow rates of oil and water from 10.60 to 28.26 L/min and 3.83 to 14.13 L/min, respectively, with the water volume fraction ranging from 0.13 to 0.50. The comparative analysis of flow patterns and frictional pressure gradients in upstream and downstream sections, respectively, is employed to evaluate the stability in the evolution of core-annular flow (CAF) by the influence of the elbow. The impacts of water input fraction and oil flow rate on the flow parameters are discussed, and the drag reduction effect is assessed by estimating the reduction factor and oil transport efficiency. The results obtained can provide a reference for the pipeline transportation system with elbow components and the optimum operational conditions that are suitable for actual applications. (C) 2020 Elsevier Ltd. All rights reserved.