Influence of Delta Wing on Wall Erosion Characteristics of Mitred Pipe Bends Handling Coal Slurries

Abstract

The present work investigates the influence of delta wing vortex generators placed inside circular mitred pipe bends, handling high density and erosive coal slurries. Coal slurry flowing at different Reynolds numbers ranging from 2000 < Re < 10,000 is tested. Mitred bends having a flow turning angle (α) of 45°, formed by joining segments of pipe, with varying number of joints (1, 2 and 3) were assessed numerically. Delta wing was positioned inside the pipe at different angles (β = 30°, 60°, 90°, 120° and 150°). Coal slurry viscosity and density varied to understand the influence of solids loading (φ = 30%, 35%, 41%, 42%, 43%, 44%) on the wall erosion characteristics. Computational studies are carried out on a 90° turning circular sectioned smooth pipe bend to study the impact of various turbulence models, and the results are validated with appropriate results from the literature. A turbulence model having good correlation with the literature results is identified and adopted in the present study. Highest turbulent mixing at the pipe outlet and reduced peak wall shear stress were considered as criterion for selecting best delta wing orientation, though with a higher pressure drop penalty. Unique delta wing induced vortex flow evolutions in the streamwise direction is reported.