FLAME SPEEDS IN COMBUSTIBLE VORTEX RINGS

Flame speeds in vortex rings of a stoichiometric methane/air mixture h ave been investigated. The flame speeds have been measured by a high-s peed video camera, and the maximum tangential velocities in the vortex have been measured by a hot-wire anemometer. Results show that the fl ame velocity is approximately proportional to the maximum tangential v elocity and its proportionality factor is about unity. By considering conservation of mass, linear momentum, and angular momentum across the flame, a simple theory has been proposed. A good agreement has been o btained between the theory and the experiment. The vortex bursting mec hanism and the baroclinic torque mechanism have been discussed. (C) 19 98 by The Combustion Institute.