Change in Surface Roughness under the Influence of a Cloud of Solid Particles

The surface of a body under impingement of solid particles of two-phase flow is subject to deformation and destruction and, thus, changes its roughness. The depth of a crater, which originates from the impact of a solid particle, is determined on the base of semi-empirical theory of penetration of a spherical pellet into the surface of a target. The inertial penetration of an absolutely rigid sphere into a metallic half-space of the target is considered. The expression for maximum depth of the penetration of a spherical striker into a half-space in a wide range of dimensionless parameters changing is obtained. The obtained data of calculation of penetration depth and experimental data are compared. The evolution of a surface roughness during the action of solid particles of two-phase flow is reviewed. The value of probability of a particle fall into a crater on the surface left by previous particles is obtained. The estimation is conducted on how fast the surface of the model is covered by the craters under impingement of solid particles. It is revealed, that some seconds of presence of the experimental model in two-phase flow are enough for the solid particles to begin to drop on the surface that has been deformed by the previous particles. Therefore, when defining experimentally the coefficients of restitutions under interaction of solid particles of two-phase flow with the model it is necessary to allow for a surface roughness changing, which originates from impacts of particles.