Numerical simulation on the nonaxisymmetry arc characteristics in narrow gap TIG welding: responses to welding parameters

Narrow gap TIG welding is a high efficiency and low-cost welding technique for heavy structures building. Due to the narrow groove’s constriction, the TIG arc characteristics are different from butt welding. Understanding the unique arc characteristics of narrow gap TIG welding is the foundation for investigating the heat and mass transfer, metallurgic process, as well as process design. This research conducted numerical simulation on the TIG arc plasma in the narrow groove. The effects of welding current and arc length on the arc characteristics are investigated. Results show that, with the welding current increasing, the global velocity magnitude of plasma rises. The evolution of axial velocity and radial velocity has different responses to the current changes. The arc pressure increases drastically, and the global temperature of arc plasma also goes up. With the arc length increasing, global axial velocity rises, but the axial velocity and its gradients decrease near the anode surface. Centripetal radial velocity near the cathode increases, while centrifugal radial velocity rises at the outside of arc plasma and drops near the central axis. The maximum arc pressure on the anode surface decreases. At the lower part of the arc, arc temperature decreases near the central axis and increases at the outside of the arc.