Effects of Anode Structures on the Laminar Plasma Jet Characteristics Based on Fluent Simulation Method

Abstract

A Fluent-based simulation model was established to explore the anode current density distribution, as well as the internal temperature and velocity fields with three typical anode structures: cylindrical type, Laval type, and constricted type. First, by analyzing the relevant governing equations and theories of the laminar plasma torch, a numerical simulation model based on Fluent was developed, and its validity was verified through experiments. Then, using the constructed model, the temperature and velocity fields within the plasma torch, along with the anode surface current density distribution, were simulated and analyzed. Finally, based on a comparative analysis of the simulation results, optimization suggestions for the anode structure were proposed. The results indicate that: 1) the error between the simulation results and the experimental results of the constructed simulation model is less than 3%; 2) cylindrical-type anode current density > constricted-type anode current density > Laval-type anode current density; 3) the three typical anode structures have little influence on the temperature field within the plasma torch; however, in the anode outlet area, the outlet center temperature of the cylindrical-type anode structure is the lowest, and the radial temperature gradient is the largest; and the outlet central temperature of the Laval-type structure is slightly lower than that of the constricted-type structure, but its radial temperature gradient is the smallest, which is conducive to the uniform dispersion of the plasma flow temperature; and 4) the velocity field corresponding to the cylindrical-type structure is slightly lower than that corresponding to the Laval-type structure and the constricted-type structure. Moreover, when the Laval-type structure is adopted, the velocity in the anode area is only slightly lower than that of the constricted structure.