3D CFD Modeling and Experimental Validation for Slurry Flow Through Pipe Bend

摘要

Bends are integral part of any slurry pipeline system and are prone to excessive wear. Therefore, a detailed knowledge of the flow characteristics in the bends will enable us to identify the causes of excessive wear which in turn may help in developing remedial steps to control the excessive wear. In the present study, experimental data are collected in a 90 degree horizontal pipe bend having bend radius of 148 mm situated in a pilot plant test loop with pipe diameter of 53 mm. The experiments are performed at volumetric concentration of 16.28% of silica sand having mean particle diameter of 448.5 micron. The flow velocity was varied from 1.78 to 3.56 m/s. Separation chambers are provided at each pressure tap for interface separation of slurry and manometric fluid, water being the intermediate fluid. For better accuracy, pressure drop along the pipeline is measured by an inclined manometer. Electromagnetic flow meter is used for the measurement of slurry discharge. It is observed that pressure drop along the pipe bend increases with flow velocity. The experimental data collected in the present study have been compared with the three-dimensional computational fluid dynamics (CFD) modeling, using Eulerian two-phase model and commercial CFD package FLUENT 6.2. Eulerian model expands the definition of continuum assumption to the dispersed phase and treats both continuous and dispersed phases separately as two phases. Both phases are linked using the drag force in the momentum equation. The standard k-epsilon model is used to treat turbulence phenomena in both the phases. The granular theory for the liquid-solid flow of the Eulerian model is introduced. Gambit software is used for the development of mesh. It is observed that CFD modeling gives fairly accurate results for almost all the pressure drop data considered in the present study. CFD modeling results for concentration and velocity profiles for collected experimental data have also been presented.