Design optimization of hemispherical protrusion for mitigating elbow erosion via CFD-DPM

Pneumatically conveyed particles are commonly responsible for triggering the erosion process by impacts on the wall. Elbows with hemispherical protrusions had been proposed to mitigate erosion. Numerical simulations were carried out using the experimentally verified CFD-DPM method. The continuous impact of particles and secondary flow made the erosion scar on the extrados surface appear as an ellipse with v. For a single row of protrusions, a small arrangement angle and a large protrusion radius is more effective in improving the erosion resistance of the elbow. When θ = 30° and r = D/6, the maximum erosion rate could be reduced by up to 36.59%. The multiple rows of protrusions further mitigated the erosion of the elbow and can reduce the maximum erosion rate by 39.09% at most, but it will cause greater flow resistance. •Protrusions can reduce the maximum erosion rate by 39.09% at most.•Multiple rows of protrusions have a better effect but greater flow resistance.•Protrusions can disperse particle flow, form vortex, and inhibit secondary flow.•A large protrusion radius r and a small position θ are better choices.