Abstract: In this paper, a three dimensional model of DC arc thermal plasma torch was established. The CFD software FLUENT was then used to simulate the spatial distribution of temperature and velocity for nitrogen thermal plasma, and the influence of the working gas flow on the spatial distribution of temperature were studied base on the model. The results show that the highest plasma temperature occurs near the cathode and decreases with increasing the axial distance, while the situations will reverse for plasma velocity and it reaches the maximum at the torch exit. There was no significant effect on the spatial distribution of plasma temperature by increasing the working gas flow rate, while the plasma temperature tends to decrease as increasing the working gas flow rate.

Key words: Numerical simulation, thermal plasma, flow character, heat-transfer character