Numerical simulation on the effect of shielding gas on the plasma cutting arc

Abstract

By comparing two diffierent torch geometries, it was found that the shielding flow has no significant effect on plasma velocity and temperature,except in the shock wave region. The shielding flow decreases the shock wave, and increases the arc voltage due to cooling. In the impinging geometry, shielding flow will crash the plasma jet after the nozzle exit and slightly increase the pressure in the torch. It was also shown that the component of shielding gas has no significant effect on plasma cuttingarc. The mole fraction of oxygen decreases very slowly along the axis and is still more than 90% at 10 mm downstream the nozzle exit.