Numerical analysis of the erosion characteristics of hemispherical protrusion elbow

A surface structure with hemispherical protrusions is designed to reduce the erosion of the elbow in the gas-solid two-phase flow, and its erosion distribution and internal flow field structure are analyzed. According to the CFD-DPM method, the gas phase is used as the continuous phase and the particles are as the discrete phase. The calculation is carried out by combining the two-way coupling, RNG k-ε turbulence model, Finnie erosion prediction model, Grant particle rebound model and roughness model. The calculation results are compared to verify the accuracy of the calculation. In standard elbows, the main location where erosion occurs is the outer wall θ=50° to θ=65°, and the maximum erosion rate is 4.56×10–4 kg/(m2·s). For curved pipes with protrusions on the surface, when the protrusion position θ=30°, the maximum erosion rate reaches the lowest, which is 2.82×10–4 kg/(m2·s); when the protrusion position θ=75°, the maximum erosion rate of the maximum rate is 6.61×10–4 kg/(m2·s); the maximum erosion rate on the protrusion is 4.99×10–4 kg/(m2·s) at θ=60°. The maximum erosion rates of protrusions in other locations are lower than 3.5×10–4 kg/(m2·s), but the average erosion rate is higher. Setting a hemispherical protrusion at a specific position on the surface of the elbow can change the particle trajectory, reduce the influence of the secondary flow, and form a buffer vortex downstream of it, thereby protecting the wall. Especially when the protrusion position is θ=30° and the radius r=D/7, the maximum erosion rate will be reduced by 37.05% compared with the standard elbow. But as the position of the protrusion moves back, its protective effect gradually will be weaken. © 2021, Chongqing Wujiu Periodicals Press. All rights reserved.