A comprehensive study on multiphase flow through pipeline and annuli using CFD approach

Abstract

The physical phenomenon of more than one state or phase (i.e. gas, liquid or solid) simultaneously flowing is defined as multiphase flow. The overall performance of multiphase flow is more complex compared to single phase flow through pipeline or annuli. Calculation accuracy of pressure drop, and particle concentration is very important to design pipeline or annular geometry for multiphase flow. The objectives in the present study are to design a CFD model that can be used to predict multiphase fluid flow properties with more accuracy; to validate proposed CFD model with experimental data and existing empirical correlations at different orientations of geometry and combination of fluids; and to investigate the effects of pipe diameter, wall roughness, fluid velocity, fluid type, particle size, particle concentration, drill pipe rotation speed and drill pipe eccentricity on pressure losses and settling conditions. Three distinct phases of working fluids are used to fulfill the project. Simulation process is conducted using ANSYS fluent version 16.2 platform. Eulerian model with Reynolds Stress Model (RSM) turbulence closure is selected as optimum to analyze multiphase fluid flow. Pressure gradient and sand concentration profile are the primary output parameters to analyze. This article combines validation work at all possible cases to verify the developed model and parametric study to observe the effects of selected parameters on particle deposition. In parametric analysis, eccentricity of the annular pipe is varied from 0 – 50% and rotated about its own axis from 0 – 150 rpm. The diameter ratio of the simulated annuli is 0.56. Results show very good agreement with existing experiments and developed correlations. Also, the effects of different parameters are briefly analyzed with proper explanations. Fluid Structure Interaction (FSI) is introduced to observe the fluid flow effect on pipeline deformation.