Transient Two-Dimensional Calculations of Properties of Forced Convection-Stabilized Electric Arcs

We describe a transient two-dimensional model of forced convection-stabilized electric arcs, such as those which occur in gas-blast circuit breakers. The model solves the local thermodynamic equilibrium (LTE) conservation equations of mass, momentum, and energy by a combination of finite-difference and finite-element techniques. Salient numerical features of the model are an adaptive mesh and the use of a controlled amount of artificial diffusion. The model yields good agreement with experiments for the upstream region of steady-state arcs in nitrogen and sulfur hexafluoride. Transient simulations of SF6 arcs, which are ramped to current zero and allowed to decay freely, also agree well with measurements of temperature and dielectric recovery. In distinct contrast to previous theoretical work [1], our model takes no account of turbulence. The close agreement of our laminar model with experiment leads us to conclude that turbulence has negligible effect on the temperature recovery of the upstream region of the flow-stabilized arcs we have simulated, and hence on the dielectric recovery of these arcs.