Contribution of Axial Arc Pressure Gradient Near Cathode on Enthalpy Flow of Arc to Axial Direction with Lateral Gas

Abstract

The arc affected by the lateral gas is deflected to leeward, and the problem of heat transfer decrement occurs in the base metal at the arc welding. The elucidation of arc deflection is necessary with the lateral gas. It has been researched that the heat transfer decreases with increasing the arc deflection length. However, the measurement of arc pressure is difficult because the plasma jet affected by lateral gas flows to leeward. For this reason, the arc stiffness has not been elucidated at the only experiment with lateral gas. The understanding of correlation between the plasma jet and heat transport affected by the convective heat transfer is necessary using 3-D numerical analysis for the elucidation of the arc stiffness. In this paper, the contribution of axial arc pressure gradient near cathode on the enthalpy flow of arc to axial direction with the lateral gas was elucidated. As a result, the mean convective force in arc periphery part increased a bit and the axial arc pressure gradient did not change in the case of the low lateral gas flow velocity. The total heat transfer derived from the enthalpy flow to axial direction did not change because the axial arc pressure gradient was higher than the convective force of lateral gas. In contrast, the mean convective force in arc periphery part increased and the axial arc pressure gradient decreased in the case of the high lateral gas flow velocity. The total heat transfer derived from the enthalpy flow to axial direction decreased because the plasma jet affected by the convective force of lateral gas move to leeward direction. Therefore, the axial arc pressure gradient plays an important role for the prevention of arc deflection.