Interactions of Free-Burning Arcs with Transverse Gas Flows and Magnetic Fields

摘要

Interactions between a free burning arc and transverse gas flows without and with magnetic fields perpendicular to the arc axis are studied. For simplification the arc plasma is described by the mono-fluid-approximation, laminar flow is assumed and the problem is reduced to two dimensions. The latter is approximately correct near the symmetry-plane between the electrodes of a very long free burning arc. Analytical and numerical methods are developed to calculate the flow for a given reasonable temperature field and the temperature distribution for a given flow field. For a given approximate temperature distribution the momentum equation is solved including inertial forces, viscous forces and Lorentz forces. An analytic solution for a channel model is compared with the more rigorous numerical calculations. It is shown that strong magnetic fields or inertial forces can cause a back-flow in the arc core. A better approximation of the temperature field is found by solving the energy equation for a given inhomogeneous flow field. The solution leads to an eigenvalue problem, which allows besides the calculation of the temperature distribution a determination of the electric field strength in the arc depending on the flow parameters.