Analysis of the arc formed along the surface of a flat plate immersed in a laminar flow of gas

In crossblast circuit breakers the residual arc is driven by gas flow into a series of plates (chutes) which, in effect, `cut¿¿ the arc and so achieve extinction. This process is analysed using a conventional similarity boundary layer approach. The arc forms a sheet current flowing adjacent to the plane surface which is itself parallel to the gas flow. In contrast to previous calculations, the arc is not restricted within a channel but, with increasing distance downstream, continues to expand into the flowing gas. Empirical relations are used to describe the known gas parameters, such as electrical conductivity, viscosity etc., in terms of temperature, and the resulting balance between heat conduction, convection and Joule heating is solved to yield temperature profiles through the arc and the electric field-current characteristics of the system. It is found that the electric field-current characteristics essentially reduce to an electric field ¿¿ (current)¿¿0.50 dependence, which is not unlike that observed with both stationary arcs and with nozzle flows.