Simulation of Free Burning Arcs and Arcs Inside Cylindrical Tubes Initiated by Exploding Wires

This paper is devoted to fundamental physics and numerical simulation of arcs initiated by an exploding wire. That is primarily used to perform simplified experiments on switching arcs without having complex moving contacts or for study the switching arc under controlled conditions. One of the main issues in the accuracy of these experiments is that a certain amount of metal vapor is inserted into the arcing medium, which can affect the switching arc characteristics through affecting the thermodynamic characteristics of the gas mixture. The current study aims to address this issue by solving the magneto-hydrodynamics (MHD) equations in local thermodynamic equilibrium (LTE) for temperature and electric potential. Impact of copper vapor on arc characteristics has been considered throughout modeling thermal and electrical conductivity as well as radiation properties for metal vapor percentage in the gas mixture. Current magnitude effect on arc characteristics is studied through increasing arc current to 300 and 600 A in experimentally verified MHD model for the free-burning arc. Results of the experimental setup are utilized to support and verify this study. Effects of severely arc quenching through very narrow tubes (150 A through nozzle diameter of 2 mm) on thermal arc behavior, maximum current density inside the tube and arc voltage oscillations near current zeros are investigated through MHD simulations. The simulation results show good agreement with the experimental results except at current zeros, where the LTE conditions are not fulfilled.