Insights Into the Arrangement of Main Working Gas and Powder Carrier Gas on Gas–Particle Flow Dynamics in Cold Spraying

During cold spraying, the interaction between the powder carrier gas and the main working gas plays an important role in determining coating quality and deposition efficiency by influencing both gas flow dynamics and particle behavior. However, comparative studies examining the effects of different gas stream designs on gas flow fields and particle acceleration behaviors remain limited. In this study, three key configurations of the two gas streams—coaxial, 45° inclined, and perpendicular—are systematically analyzed through numerical modeling. The configuration of the two gas streams considerably affects the gas temperature distribution and particle acceleration behavior upstream of the spraying gun but exhibits minimal influence on the velocity field downstream and the particle impact area on the substrate. When the two gases are placed at a 45° angle, the preheating effect on the powder carrier gas and particles is optimal. However, this arrangement also leads to the most severe particle backflow, increasing the probability of particle–wall collisions, which in turn increases the risk of nozzle blockage. In comparison, when the gas streams are arranged perpendicular to each other, the particle backflow phenomenon and nozzle clogging risk drastically decrease, and this risk is further minimized when the two gases are coaxial. Therefore, for low-melting-point powders that are prone to nozzle clogging (such as aluminum), coaxial or perpendicular gas arrangements are recommended. For high-melting-point particles that are less likely to clog the nozzle (such as copper), a 45° gas arrangement is preferred to optimize particle impact temperature, thereby improving coating quality. The outcomes present valuable insights into the benefits and limitations of the three distinct arrangements between the powder carrier gas and the main working gas, broadening the understanding of their effects on particle deposition efficiency and coating quality.