Three-dimensional isothermal solid-gas flow and deposition process in a plasma spray torch with solid shield: A numerical study

Three-dimensional isothermal solid-gas turbulent flow and deposition process in a plasma jet with solid shield is numerically investigated in the present study. Four process parameters, including the velocity ratio of the particle carrier-gas and the plasma jet, the particle injection position, the particle size and the particle density, are varied to examine their effects on the flow field and the particle deposition performance. The particle deposition efficiency, distribution non-uniformity and average impact velocity on the substrate are defined in the study as three indicators for evaluating the deposition quality. The analyzed results show that the velocity ratio has evident influence on all of the indicators. In the three different velocity ratio cases, the case of velocity ratio equal to 1/100 has the best deposition efficiency and the most uniform deposition distribution. The lateral position of the injection particle carrier-gas only mildly influences the uniformity of the deposition, but has effective influence on the deposition efficiency and the average impact velocity. In the cases with smaller particle size and larger particle density, the deposition efficiency is higher and more uniform, whereas the average impact velocity is larger in the cases with smaller particle size and lighter density.