Physics of an arc in cross-flow

Summary form only given. The quantitative description of an electric arc which is exposed to a cold gas flow from a direction perpendicular to the arc axis poses several difficulties. The major one is the need for a fully three dimensional treatment and the lack of symmetry at the boundaries. We present a theoretical treatment of such an arc with the development of a computer code for solving the three dimensional conservation equations. Validation of this code has been performed by obtaining computational results for conditions for which experimental data exist. The calculations yield temperature and velocity fields and distributions of current density and potential. Results are presented for conditions encountered in the application of a wire arc spray process: an arc current of 100 and 200 A and an arcing gap of 1 mm and 2 mm, and a configuration where the electrodes are sections of a nozzle. The plasma gas has been argon, and a range of cross flow velocities has been investigated. The results show that the location of highest temperature is downstream of the location of highest electric field and highest power dissipation because of the asymmetric energy transport. The anode attachment is less constricted and farther downstream than the cathode attachment, however the flow turbulence essentially eliminates the differences in the temperatures and velocities caused by the difference in electrode attachments a short distance downstream. This code can be used to illustrate the influence of the physical parameters in processes where arcs in cross flow are encountered.