Two-Phase Flow Analysis in Elbow Bend Pipe Used in Oil Extraction Process: A Computational Approach

Abstract

To predict and analyze the mechanical fatigue and other damages in pipelines, caused by slug flow in petrochemical industry, large amounts of research have been assigned in understanding and prognosis of slug flow transition in straight and bend pipes. Accurate predictions of liquid hold up, pressure distribution and velocity are imperative for uninterrupted operation of the facility before actual work being carried out. With the above-mentioned motivation, this paper focuses on investigation of oil–water and oil–air two-phase flow formation in straight pipes and bend pipes and its associated pressure drop, maximum velocity and volume of fraction. Mixture model has been adopted in this computational analysis. Newtonian behavior of oil–air and oil–water interface is obtained from the model through a vertical 90° elbow with 50.2 mm pipe diameter. Four different oil velocities such as 5, 10, 15 and 20 m/s along with three air and water velocities 0.5, 1 and 2 m/s, respectively, are used in this study. Velocity distribution and pressure profile at six sections of 90° elbow are obtained and compared in order to analyze the flow pattern behavior. CFD analysis results under mixture model show a decreasing trend in pressure as mixture exits the elbow. Furthermore, it also shows a larger decrease in pressure at higher oil velocities. There is an increase in mixture velocity as the oil velocity rises as well as the water/air velocity increases. Similarly, for increase in VOF from 0.25 to 0.5, there is a significant decrease in pressure as well as increase in velocity is observed. The model can be helpful in designing pipeline and piping systems for oil extraction as well as oil refineries.