Visual investigation of a vortex ring interacting with a nonpremixed flame

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 fro m a round nozzle and then igniting it by means of a residual flame sustaine d at the nozzle tip. Flow visualization was conducted through a time resolv ed Mie scattering, Schlieren, and flame luminosity records. The favorable r ange of lest conditions, in which flame extinction caused by excessive stra in does not occur, was provided. The main effects of combustion on the vort ex are the significant alterations in the ring celerity as well as its grow th rate, and the retardation of its instability. The comparison between ver tically upward and downward evolving vortex flames showed that buoyancy for ce 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 Karagozi an and Manda (1986).