In this study, a downstream injection cold spray nozzle is modeled numerically under various loadings. Instead of micron-sized particles, liquid feedstock as a carrier of nanoparticle suspension is fed into the nozzle through a port located 6 mm downstream of the nozzle throat at the diverging section. Water is used as the liquid carrier with a droplet size distribution of 5-100 µm and liquid-to-gas ratio ranging from 5 to 15%. The radial injection of droplets is simulated by Lagrangian particle tracking which includes the effects of heating and evaporation. The effect of the feedstock on downstream flow is analyzed and the optimum solid-to-liquid fraction in the suspension is determined.

This study investigates the effect of water injection in the high pressure chamber of a cold spray nozzle. A de Laval nozzle geometry with constant back pressure and temperature is modeled numerically using Reynolds Stress Model coupled equations. Water spray with a droplet size of 10 – 100 μm is modeled using both uniform and Rosin-Rammler size distributions. The two-phase flow of gas-liquid is modeled using an unsteady discrete phase mass source with two-way coupling with the main gas flow. Upon injection, the droplets in the water spray evaporate while travelling through the nozzle due to momentum and energy exchange with the gas flow. The evaporation behavior in presence of water content is modeled and a correlation between the initial diameter and the diameter just before the throat is obtained. As a result, the proper droplet size distribution with a fully evaporative spray can be used as a carrier of nano-particles in cold spray nozzles. Having the results, guide us to substitute the un-evaporated part of the droplet with an equal diameter agglomerate of nano particles and find a minimum fraction of nano particles suspended in the liquid which guarantees fully evaporative liquid spray injection.