Predicting Erosion from Airborne Particles on Surfaces using a Soft-Sphere Collision Model

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American Institute of Aeronautics and Astronautics


In this study, we hypothesize that the soft-sphere collision model has the ability to simulate the erosion that occurs when airborne particles impact a surface. The key insight in this paper is to connect the particle-surface work performed during impact to the amount of erosion on the surface. This can only be done through the introduction of a new collision modeling strategy. This paper borrows the soft-sphere modeling approach from the DEM community, and uses it in a new context to model particle impact and surface erosion.

In the aerospace literature, the most commonly used collision approach is the hard-sphere model. Here the trajectories of the particles are determined by momentum-conserving binary collisions characterized by a coefficient of restitution. This model is limited in that it is not capable of predicting the physical interactions that occur simultaneously to particle impact such as surface erosion and any adhesive processes. On the other hand, the soft-sphere model is a physics-based approach which represents the particle as a Kelvin-Voigt material. The approach explicitly resolves the impact by introducing a spring-dashpot force to the governing dynamical equation for particle motion. The spring force is non-zero only when the particle is in contact with the wall.

One underexplored consequence of this approach is that it provides a time history of the particle-surface work. This information may be used in turn, to compute the amount of surface erosion. This paper uses the given information to develop a modeling approach that resolves both particle-surface collisions and surface erosion under a single framework. This model is validated using the coefficient of restitution and erosion data of Grant and Tabakoff[1, 2], which was defined for sand particles. The model is then applied to look at particle erosion on a single stage rotor-stator configuration.