Turbulent Partially Premixed Dimethyl Ether/Air Jet Flames: A New Series of Target Flames for Experiments and Modeling

摘要

We introduce a new series of benchmark flames consisting of partially premixed piloted dimethyl ether (DME)/air jet flames. These flames provide an opportunity to understand turbulence-flame interactions for oxygenated fuels and to develop predictive models for these interactions. The development of accurate models for DME/air flames would establish a foundation for studies of more complex oxygenated fuels. This series of four jet flames spans jet exit Reynolds numbers, Re_d, from approximately 27,000 to 68,000. The flames are stabilized on the same burner as the piloted CH_4/air jet flames that have been studied extensively within the context of the TNF Workshop. The fuel mixture consists of 20% DME and 80% air, by volume, resulting in a stoichiometric mixture fraction of ξ_(st) ＝ 0.353, which is the same as that of the piloted CH_4/air flames with 25% CH_4 and 75% air. Flame conditions range from very low probability of localized extinction to a high probability of localized extinction and subsequent re-ignition. In an initial survey of these flames, we use laser-induced fluorescence (LIF) imaging of OH to measure the reaction zone structure, the probability of localized extinction, and the size distributions of the extinguished regions.