Numerical simulation and experimental study of Ar-H-2 DC atmospheric plasma spraying

Thermal plasma spraying technology has been widely used in many industrial applications, such as gas turbines, energy and semiconductors, etc. However, the relationship between the characteristics of plasma arc/jet and spraying parameters is not fully understood yet. This paper aims to investigate the plasma heat transfer and flow during the plasma spraying process by numerical simulation and experimental measurement, and to analyze the effect of working current on plasma arc and the corresponding flow fields. To achieve this objective, a three dimensional (3D) time-dependent numerical model that includes the inside and outside of the torch regions was developed, and the Enthalpy probe system was used to diagnose the properties of the plasma jet. The results show that the plasma temperature and velocity distributions have significant 3D asymmetric features. The increase of working current lead to decrease the arc length but increase its radius, the effective electric power was increased and resulted in increasing the plasma temperature and velocity, while the thermal efficiency was reduced. The plasma jet core with high temperature and velocity was extended both in radial and axial directions. Additionally, the predicted results were in fair agreement with the measured ones.