Spatial-frequency-resolved schlieren sensor for turbulence visualization in arc discharge

A spatial-frequency-resolved Schlieren photography was developed for the temporally-sequential visualization of the size-selected, multi-directional turbulent structures induced by the arc discharge in a model type gas circuit breaker. The Schlieren-based method was applied to the atmospheric-pressure DC 55-A arc discharge under gas blasting of 100%CO 2 , 90%CO 2 10%C 2 F 6 or 80%CO 2 20%C 2 F 6 , where C 2 F 6 was used as a substitute additive of commercially available polyatomic molecules. The visualization results clearly demonstrated that strong non-reproducible turbulence existed only for the C 2 F 6 -blended CO 2 gases. The turbulence size was smaller with increasing the radial distance from the arc. The arc-discharge-induced turbulence showed circular structures in 1–5 mm diameters, which was peculiar to the C 2 F 6 -blended CO 2 gases. The turbulence existence realizes high interruption performance of gas circuit breakers, which provided a new aspect for the search on the SF 6 -alternative gases.