CFDEM modelling of particle heating and acceleration in cold spraying

Cold spraying is a promising approach for the processing of refractory metals. A powder material is accelerated and heated in the gas flow of a supersonic nozzle to velocities that are sufficient to obtain cohesion of the particles to a substrate due to plastic deformation. The cohesion behavior of the particles is mainly determined by their velocity and temperature. These are controlled by the pressure and temperature of the gas at the nozzle entrance. A correlation of the process parameters gas pressure and temperature with the particle velocity and temperature is possible based upon numerical simulations. In this contribution a CFDEM simulation model for particle heating and acceleration based on OpenFOAM and LIGGGHTS is presented. CFDEMcoupling combines computational fluid dynamic (CFD) calculation of the gas flow based on the finite volume method with a description of the particles based on the discrete element method (DEM). The predictions of the simulation model are verified based on an analytical description of the cold spray nozzle and validated by experimentally measured particle velocities. Based on this experimental validation the drag model of Koch and Hill appears best suited for a CFDEM modelling of cold spraying.