Modeling and simulation of a heat source in electric arc welding

Paper in proceeding, 2011

This study focused on the modeling and simulation of a plasma heat source applied to electric arc welding. The heat source was modeled in three space dimensions coupling thermal fluid mechanics with electromagnetism. Two approaches were considered for calculating the magnetic field: i) three-dimensional, and ii) axi-symmetric. The anode and cathode were treated as boundary conditions. The model was implemented in the open source CFD software OpenFOAM-1.6.x. The electromagnetic part of the solver was tested against analytic solution for an infinite electric rod. Perfect agreement was obtained. The complete solver was tested against experimental measurements for Gas Tungsten Arc Welding (GTAW) with an axi-symmetric configuration. The shielding gas was argon with thermodynamic and transport properties covering a temperature range from 200 to 30 000 K. The numerical solutions then depend greatly on the approach used for calculating the magnetic field. The axi-symmetric approach indeed neglects the radial current density component, mainly resulting in a poor estimation of the arc velocity. Various boundary conditions were set on the anode and cathode. These conditions, difficult to measure and to estimate a priori, significantly affect the plasma heat source simulation results. Solution of the temperature and electromagnetic fields in the electrodes will thus be included in the forthcoming developments.