Numerical simulation of Ar-x%CO2 shielding gas and its effect on an electric welding arc
Konferensbidrag (offentliggjort, men ej förlagsutgivet), 2011

This study focuses on the simulation of a plasma arc heat source in the context of electric arc welding. The simulation model was implemented in the open source CFD software OpenFOAM-1.6.x, in three space dimensions, coupling thermal fluid mechanics with electromagnetism. Two approaches were considered for calculating the magnetic field: i) the three-dimensional approach, and ii) the so-called axisymmetric approach. 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 axisymmetric configuration. The shielding gas was argon, and the anode and cathode were treated as boundary conditions. The numerical solutions then depend significantly on the approach used for calculating the magnetic field. The so-called axisymmetric approach indeed neglects the radial current density component, mainly resulting in a poor estimation of the arc velocity. Plasma arc simulations were done for various Ar-x%CO2 shielding gas compositions: pure argon ( x =0), pure carbon dioxide ( x =100), and mixtures of these two gases with x =1 and 10% in mole. The simulation results clearly show that the presence of carbon dioxide results in thermal arc constriction, and increased maximum arc temperature and velocity. Various boundary conditions were set on the anode and cathode (using argon as shielding gas) to evaluate their influence on the plasma arc. These conditions, difficult to measure and to estimate a priori, significantly affect the heat source simulation results. Solution of the temperature and electromagnetic fields in the anode and cathode will thus be included in the forthcoming developments.

WIG

spatial distribution of thermal energy

thermal plasma

inert gas

electric heat source

magnetic potential

TIG

electric arc welding

active gas

GTAW

Författare

Isabelle Choquet

Håkan Nilsson

Chalmers, Tillämpad mekanik, Strömningslära

Alireza Javidi-Shirvan

Chalmers, Tillämpad mekanik, Strömningslära

Nils Stenbacka

IIW Commission XII / SG 212 Intermediate meeting, University West, Trollhättan, Sweden, 21 - 23 March 2011, IIW Doc. XII-2017-11

Drivkrafter

Hållbar utveckling

Styrkeområden

Produktion

Ämneskategorier

Bearbetnings-, yt- och fogningsteknik

Strömningsmekanik och akustik

Fundament

Grundläggande vetenskaper