The acceleration of micro- and nano-particles in supersonic De-Laval-Type nozzle

The particle velocity in cold gas dynamic spraying (CGDS) is one of the most important factors that can determine the properties of the bonding to the substrate. The acceleration of gas to particles is strongly dependent on the densities of particles and the particle size. In this paper, the acceleration process of micro-scale and nano-scale copper (Cu) and platinum (Pt) particles in De-Laval-Type nozzle is investigated. A numerical simulation is performed for the gas-particle two phase flow with particle diameter ranging from 100nm to 50µm, which are accelerated by carrier gas Nitrogen in a supersonic DeLaval-type nozzle. The results show that cone-shape weak shocks (compression waves) occur at the exit of divergent section and the particle density has significant effect on the accele ration of micro-scale particles. At same inlet condition, the velocity of the smaller particles is larger than the larger particles at the exit of the divergent section of the nozzle