The spontaneous onset of oscillations in jet diffusion flames near extinction were studied. A simple theoretical study, which was conducted to understand the basic mechanisms responsible for the onset of oscillations, was shown to predict trends that were consistent with the observations. The theoretical predictions were based on a simple configuration in which fuel was supplied in the feeding stream and oxidant diffused against the stream. The undisturbed flame was assumed planar with the oscillations occurring normal to the reaction sheet. The oscillations occurred at near-extinction conditions, or when the Damkoehler number was sufficiently large (typically larger than one). The onset of oscillations was sensitive to the initial mixture strength. Oscillations happened mostly when the initial mixture strength was increased or when heat losses were excessive. Theoretical estimates of the frequency at the onset of oscillation yield 1-5 Hz for the current experimental range of Lewis numbers and initial mixture strength. Patterns similar to those predicted by the simple model described were noted for jet diffusion flames. At near-extinction conditions self-excited oscillations were noted for hydrocarbons, such as propane or methane, burning in air or oxygen-inert mixtures. The flame oscillations in the streamwise direction were noted to be axisymmetric. Original is abstract.
|Original language||English (US)|
|Number of pages||1|
|Journal||International Symposium on Combustion Abstracts of Accepted Papers|
|State||Published - Jan 1 2000|
|Event||28th International Symposium on Combustion - Edinburgh, United Kingdom|
Duration: Jul 30 2000 → Aug 4 2000
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