Physics of an arc in cross flow

Abstract

Arcs in cross flow are encountered in a number of applications, forexample in wire arc spraying. Optimization of such processes has relied inthe past on an empirical approach and on intuition based on a qualitativeunderstanding of the process. A theoretical treatment of an arc exposed to acold gas flow perpendicular to its axis requires a three-dimensional (3D)formulation. A computer code has been developed to solve the 3D conservationequations for an atmospheric pressure argon arc in cross flow, and this codehas been validated by comparison with previously published experimentalresults. Results have been obtained for typical conditions encountered in awire arc spray situation, arc current 100 to 200 A, and arcing gaps of 1 and2 mm, and varying cross-flow velocities. Results are presented in the form oftemperature and velocity fields, and current density and potentialdistributions. It is apparent that the location of the highest temperaturedoes not coincide with that of the highest electric power dissipation because oftransverse convective effects, and that the anode attachment is fartherdownstream than the cathode attachment. The results clearly indicate that 3Dmodelling is required to capture the physical effects of the arc in crossflow, and that the code can be used to illustrate the parametric dependencesof the plasma flow in various cross-flow situations.