The aerodynamics of electric arcs in axial flow

This thesis investigates the behaviour of a d.c. electric arc under the influence of a number of different axial gas flow conditions. The work is directed towards obtaining a greater understanding of the electric arcs produced within gas blast circuit breakers. In order to eliminate as many variables as possible, detailed experiments have been carried out in constant pressure, subsonic nitrogen flow provided by a low Mach number shock tube. This facility enables the flow velocity and pressure to be varied independently, thus allowing their effect on arc behaviour to be studied separately. A simplified theoretical model of the arc in this flow field has been developed which gives excellent agreement with the shock tube experiments. The solution of the theoretical model is obtained in non-dimensional terms as a universal characteristic for the constant pressure axial flow arc…