Investigation of Non-axisymmetric Gas Arrangement: Effect of Pressure Differential on Gas-Solid Two-Phase Flow

This study presents a three-dimensional non-axisymmetric numerical model to investigate the effect of the pressure differential (ΔP) between the powder carrier gas and the main working gas, arranged at a 45° angle, on the flow field distributions inside and outside the spraying gun, as well as on the Al particle accelerating and heating behavior during the cold spraying process. The numerical results indicate that, under a non-axisymmetric gas arrangement, an increase in ΔP significantly lowers the temperature of the mixed gas upstream of the spraying gun, consequently reducing the Al particle impact temperature. However, ΔP has a negligible effect on both the gas velocity and the Al particle impact velocity. Furthermore, the extent of Al particle dispersion within the spraying gun and the Al particle distribution on the substrate remain unaffected by ΔP variations, contrasting sharply with the behavior observed in coaxial gas arrangements. To validate the numerical predictions, single-pass cold spraying experiments were conducted to deposit Al coatings. Experimental results demonstrate that the width of the Al particle impact area on the substrate closely coincides with the simulation data and the coating width is invariant to adjustments in ΔP, hence verifying the numerical simulations.