Experiments on the interaction between a vortex and a strained diffusion flame

Abstract

Flame-vortex interactions constitute a basic problem in the analysis of turbulent combustion. Vortex rollup is also found to be one of the major driving mechanisms of combustion instabilities. While there are many analytic and numerical studies of the process, the number of detailed experiments is relatively limited. In particular, the nonpremixed case has not been explored, apparently because the experimental configuration is less easily designed. It is shown here that this case may be 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 vortex impinges on the flame from the oxidizer side entraining the reactive layer and producing a hole in the initial flame. The apparatus is described and initial results of visualizations and velocity measurements by laser doppler anemometry are discussed. It is found that the interaction leads to different outcomes. Strong vortices produce flame extinction and a subsequent blowout. In contrast, the flame is recovered after an interaction with a weak vortex.