EXPERIMENTS ON THE INTERACTION BETWEEN A VORTEX AND A STRAINED DIFFUSION FLAME

Flame-vortex interactions constitute a basic problem in the analysis o f turbulent combustion. Vortex rollup is also found to be one of the m ajor driving mechanisms of combustion instabilities. While there are m any analytic and numerical studies of the process, the number of detai led experiments is relatively limited. In particular, the nonpremixed case has not been explored, apparently because the experimental config uration is less easily designed. It is shown here that this case may b e examined by employing a counterflow burner. A steady diffusion flame is established in this geometry and a vortex ring is generated from a cylindrical tube installed in one of the combustor nozzles. The vorte x impinges on the flame from the oxidizer side entraining the reactive layer and producing a hole in the initial flame. The apparatus is des cribed and initial results of visualizations and velocity measurements by laser doppler anemometry are discussed. It is found that the inter action leads to different outcomes. Strong vortices produce flame exti nction and a subsequent blowout. In contrast, the flame is recovered a fter an interaction with a weak vortex.