Modelling of heat flow and electromagnetic phenomena in a non-transferred plasma torch

• Over the decades, computational methods have been used to model and describe the flow andionization dynamics in plasma torches. However, the impact of the operational parameters such as gas flow rate, swirl number and input current density on flow is still inexplicit. In this study, the flow in a non-transferred plasma torch is modelled using COMSOL Multiphysics, and the influence of these parameters is studied. The analysis is carried out on an axisymmetric geometry with the conical-shaped cathode, nozzle-shaped anode, and Argon is used as the plasma gas. A thermal plasma (equilibrium discharges) is considered, i.e., the plasma is underpartial to complete local thermodynamic equilibrium in which the magnetohydrodynamic (MHD) equations are solved. This is treated in the Equilibrium Discharge Interface in COMSOL’s plasma module that has been used in the present study. The laminar flow analysisis performed for low-velocity cases and turbulent flow analysis for higher velocities. It was found that the velocity increase across the plasma arc due to ionization and gas expansion, couldbe observed only for sufficiently high plasma inflow velocities. The position of the plasma arcis determined for different operating conditions. It was further found that the velocity has anegligible effect on the length of the plasma arc, whereas the dependency of the arc length andattachment point on the anode wall, to the input current density and cathode tip temperature iswell explained. The paper concludes by presenting the variations in temperature and velocityof plasma arc due to swirling inflow.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

Nyckelord

Strömningslära

Fluid Mechanics

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