Numerical simulation of influence of nozzle structure on arc characteristics of GPCA－TIG welding

This work mainly articulated the effects of nozzle structure on arc characteristics in gas pool coupled activating TIG(GPCA－TIG)welding process by using Fluent Software．Different models were set up to adapt the different torch structure during computer progress．The specific configuration of the welding torch made the gas flow in outer gas passage constrained．The nozzle structure has great influence on outer gas distribution because of the changing of coupling region between the outer active gas and molten pool surface．When the coupling degree is reduced or the outer gas passage become smaller，the oxygen in outer gas penetrates into the arc plasma and spreads to the arc region more easily．Owing to its cooling effects，the morphology of arc is contracted，and the arc temperature is increased．When the inner wall and the outer wall of outer gas passage are not parallel，the wide top and narrow bottom nozzle shape can bring more oxygen into the arc plasma，the arc is contracted and the peak temperature of arc rises a little more comparing to the narrow top and wide bottom one．