3D time-dependent numerical simulation for atmospheric plasma spraying

The coating quality and reproducibility of plasma spraying are significantly affected by the characteristic of plasma jet that is closely related to the arc root attachment. In this study, a 3D time-dependent numerical model based on the Local Thermodynamic Equilibrium (LTE) assumption was developed to investigate the arc dynamics and its effect on the distributions of temperature and flow field both inside and outside of the torch. The results show that there is the coexistence of multiple arc roots, and the particular attachment location of plasma arc leads to a significant asymmetry in distributions of temperature, velocity as well as electric potential and field strength. The continuous movement of the plasma arc not only caused the fluctuations of the arc voltage drop, but also resulted in the temporal variations of the plasma temperature and velocity. Moreover, the predicted temperature and velocity distributions of plasma jet were in good agreement with experimental measurements.