A commercial CFD (computational fluid dynamics) code FLUENT was used andmodified to model an atmospheric pressure argon arc in a low cross flow by solving the fullycoupled conservation equations.Numerical experiments,with an arc current of 100 A to 200 A,an arcing distance of 3 mm to 6 mm,and a cross-flow velocity of 10 m/s to 30 m/s,were carriedout.The modelling results show that the arc tends to take the shortest path to the anode whendeflected by the cross flow;its anode attachment is farther downstream than the cathode one.Furthermore,due to the low input gas flow imposed in this study,the effect of electromagneticforce is important and it influences the crosscut shape of the arc significantly.
In this paper a commercial CFD(computational fluid dynamics) code FLUENT has been used and modified for the axisymmetric swirl and time-dependent simulation of an atmospheric pressure argon arc in an external axial magnetic field(AMF).The computational domain includes the arc itself and the anodic region.Numerical results demonstrate that the AMF substantially increases the tangential component of the plasma velocity.The resulting centrifugal force for the plasma rotation impels it to travel to the arc mantel and as a result,a low-pressure region appears at the arc core.With the AMF,the arc presents a hollow bell shape and correspondingly,the maximal values of the temperature,pressure and current density on the anode surface are departing from the arc centreline.
A theoretical model is presented to describe the electromagnetic,heat transfer andfluid flow phenomena within a magnetron plasma torch and in the resultant plume,by using acommercial computational fluid dynamics (CFD) code FLUENT.Specific calculations are pre-sented for a pure argon system (i.e.,an argon plasma discharging into an argon environment),operated in a turbulent mode.An important finding of this work is that the external axial mag-netic field (AMF) may have a significant effect on the behavior of arc plasma and thus affectsthe resulting plume.The AMF impels the plasma to retract axially and expand radially.As aresult,the plasma intensity distribution on the cross section of torch seems to be more uniform.Numerical results also show that with AMF,the highest plasma temperature decreases and theanode arc root moves upstream significantly,while the current density distribution at the anodeis more concentrated with a higher peak value.In addition,the use of AMF then induces a strongbackflow at the torch spout and its magnitude increases with the AMF strength but decreaseswith the inlet gas velocity.
