Influence of particle forces and sharpness factor on erosion characteristics for dilute gas-solid flow system at moderate to high Reynolds number*

Accurate estimation of particles impact velocities, impact angles and distribution in a given fluid flow are fundamental in characterising solid particle erosion. The hydrodynamic of forces acting on the particles are a key factor that can influence erosion magnitude, pattern, and the location of maximum material loss. Most numerical simulation studies for dilute gas-solid flows have focused on low to moderate particles Reynolds number (Re) and assumed drag and gravity forces as the most important forces. Here, we use the open-source libraries OpenFOAM to solve the continuity and momentum equations for the fluid phase and the particles whose motion is driven by Newton's second law, are modelled in a Lagrangian way with a Discrete Particle Model. The effects of drag, gravity, pressure gradient, virtual mass, and lift forces at high Re on erosion are studied with two test cases: the direct impingement (DI) of solids on a plate and flows through an elbow with Re > 1000. The results suggest that the particle dynamics strongly affect the angle of impact, velocity of impact, and distribution of particles. The erosion predictions appear to be particularly sensitive to drag and lift. For the DI, lift has shown a significant effect on erosion pattern and magnitude by influencing the particle distribution while the effects of lift appear negligible in the case of elbow erosion. The reason for the negligible effect for elbows may be attributed to higher degree of turbulence and mixing as the particles approach the bend. Our study of three particles sizes, 53µm, 300µm and 710µm, also show a negligible effect of lift on the 53µm for both DI and elbow geometries. The results suggest that the assumptions around individual geometries need to be carefully considered in optimising computational time and to enhance the accuracy of erosion prediction.