Visual investigation of a vortex ring interacting with a nonpremixed flame

Abstract

The interaction of a single vortex ring of gaseous fuel with a nonpremixed flame was examined. A burning vortex ring was generated by issuing fuel from a round nozzle and then igniting it by means of a residual flame sustained at the nozzle tip. Flow visualization was conducted through a time resolved Mie scattering, Schlieren, and flame luminosity records. The favorable range of lest conditions, in which flame extinction caused by excessive strain does not occur, was provided. The main effects of combustion on the vortex are the significant alterations in the ring celerity as well as its growth rate, and the retardation of its instability. The comparison between vertically upward and downward evolving vortex flames showed that buoyancy force plays a significant role in the structure and developing characteristics of burning vortex rings. The formation of a 'reacted core' was observed in a real flame, as predicted by the earlier vortex pair analysis of Karagozian and Manda (1986).