Simulation and optimization of coal-water slurry suspension flow through 90° pipe bend using CFD

Abstract

ABSTRACT The present study was carried out in an attempt to reduce head loss in 90° pipe bends for conveying coal-water slurry suspensions using computational fluid dynamics (CFD). Bend geometries were modified by altering the r/D ratios within the range of 1.5–3.0. Numerical simulations were performed using several turbulence models for a solid concentration range of 30–60% (by weight) and the results were validated with experimental data. An Eulerian multiphase model along with an SST k-ω turbulence scheme was found most appropriate and shows decent agreement with experimentation results. The mean sizes of coal particles were taken as 16 μm. Results show that head loss was increased with flow velocity and solid concentration. It was also observed that r/D ratio has a significant impact on head loss characteristics. The minimum drop in head loss was observed in a pipe bend having an r/D ratio of 2.0. The effect of flow separation and secondary flows on turbulence, flow velocity and distribution of the solid suspension inside the bend geometry was also studied with the help of contours.