Analytical model of particle interference effects in divergent erosive jets

An analytical model that describes the interference, due to collisions between an incident diverging axi-symmetric jet of spherical particles, and those rebounding from a flat surface oriented perpendicular to the jet axis (i.e., normal incidence), is presented. The model can accommodate non-uniform incident particle velocity and spatial distribution, variation in particle spacing along the jet axis, and non-elastic frictional impact kinematics. The model can be used to estimate interference effects at high flux, and to obtain the critical flux below which a given level of particle interference will occur in a solid particle erosion test. Because the equations that predict the level of interference can be solved in closed form, with the exception of an integral which must be solved numerically, implementation in erosion models is also possible. For the case of an incident jet typically used in abrasive jet micromachining applications, the model is validated against an existing computer model for a wide variety of conditions, with excellent agreement.