Integrated parametric study of a hybrid-stabilized argon-water arc under subsonic, transonic and supersonic plasma flow regimes

This paper presents a numerical investigation of characteristics and processes in the worldwide unique type of thermal plasma generator with combined stabilization of arc by argon flow and water vortex, the so-called hybrid-stabilized arc. The arc has been used for spraying of ceramic or metallic particles and for pyrolysis of biomass. The net emission coefficients as well as the partial characteristics methods for radiation losses from the argon-water arc are employed. Calculations for 300-600 A with 22.5-40 standard litres per minute (slm) of argon reveal transition from a transonic plasma flow for 400 A to a supersonic one for 600 A with a maximum Mach number of 1.6 near the exit nozzle of the plasma torch. A comparison with available experimental data near the exit nozzle shows very good agreement for the radial temperature profiles. Radial velocity profiles calculated 2 mm downstream of the nozzle exit show good agreement with the profiles determined from the combination of calculation and experiment (the so-called integrated approach). A recent evaluation of the Mach number from the experimental data for 500 and 600 A confirmed the existence of the supersonic flow regime.