Modeling steady axis-symmetric thermal plasma flow of air by a parallelized magneto-hydrodynamic flow solver

This paper discusses a parallelized magneto-hydrodynamic flow solver for modeling axis-symmetric thermal plasma flow using Cartesian grid system and taking the induced electrical and magnetic effects into account, where the magneto-hydrodynamic equations, including the continuity equation, momentum equations, energy equation, current continuity equation and turbulence transport equations are solved by a finite volume discretization in a segregated manner. The thermal plasma flow of a 476 mm long, transferred well-type plasma torch operating with air is simulated for two power conditions, i.e. I = 432 A and 901 A, to demonstrate the capability of proposed numerical model to analyze the heat and mass transfer characteristics of axis-symmetric thermal plasma flow, where the location of cathode is determined by fixing the measured voltage drop between two electrodes. The numerical calculation suggests that the high-power case can deliver an axial velocity of 400 m/s and 15,000 K in temperature at the center of torch outlet, where a strong jetting vortex is expected emitting from the torch body. The low-power case is predicted with a longer electric arc than that of the high-power one, which clearly results in a large high-temperature region between the gas inlet and cathode and unfavourable to reduce the cathode erosion and to increase thermal efficiency.