Jets produced in conventional atmospheric plasma spraying are inevitably heterogeneous due to the mechanics of a rapid gas flow entering a stagnant environment. The resulting high air content together with considerable velocity and temperature variations will adversely affect the quality of coatings. This paper applies a CFD code to simulate the effect of a solid shield and a gas shroud on the characteristics of a plasma jet. The computational results show that the geometry and gas flow rates of the shrouding systems have an important influence on the quality of the plasma flow. The work shows that shrouding can substantially reduce the entrained air content and the temperature and velocity gradients in the jet. The model is applied to predict the optimum shrouding conditions for plasma spraying.

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