Design of cold spray nozzle to optimize the particle velocity by numerical simulation

This study investigated the accelerating behavior of spray particles during cold spraying (CS) by employing a computational fluid dynamics program, FLUENT. Optimization of the dimensions of CS nozzle was conducted to maximize particle velocity. The results show that the expansion ratio, divergent length, particle density and size, operating temperature significantly influence particle acceleration. It is found that the spray particles in nozzles with long divergent length can obtain a relatively higher impact velocity, but too long divergent length will reduce the particle velocity. Besides, the particle impact velocity shows a downward trend with increasing the particle size or density. Hence, the optimal divergent length should increase with the increase of particle mass. Moreover, higher gas temperature leads to a higher particle velocity, but it has no influence on the optimal divergent length.