Onset of cells and oscillations in diffusion flames

Philippe Metzener, Moshe Matalon

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A comprehensive stability analysis of planar diffusion flames is presented (i) within the context of a constant-density model, and (ii) with variable density effects included. The analysis provides a characterization of the possible patterns that are likely to be observed as a result of differential and preferential diffusion when a planar flame becomes unstable. A whole range of physical parameters is considered, including the Lewis numbers associated with the fuel and the oxidizer, the initial mixture fraction, the flow conditions, and the hot-to-cold density ratio or thermal expansion. The two main forms of instability are cellular flames, obtained primarily in fuel-lean systems when the Lewis numbers are generally less than one, and planar pulsations, obtained in fuel-rich systems when the Lewis numbers are generally larger than one. The cellular instability is predominantly characterized by stationary cells of characteristic dimension comparable to the diffusion length, but smaller cells that scale on the reaction zone thickness are also possible near extinction conditions. The pulsating instability is characterized by planar oscillations, normal to the flame sheet, with a well-defined frequency comparable to the reciprocal of the diffusion time; high-frequency modes are also possible just prior to extinction. The expected pattern depends of course on the underlying physical parameters. Consequently, stability boundaries have been identified for the onset of one or another form of the instability. The conditions for the onset of cellular and pulsating flames, as well as the predicted cell size and the frequency of oscillations, compare well with the experimental record.

Original languageEnglish (US)
Title of host publicationCollection of Technical Papers - 44th AIAA Aerospace Sciences Meeting
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
Number of pages16
ISBN (Print)1563478072, 9781563478079
StatePublished - 2006
Externally publishedYes
Event44th AIAA Aerospace Sciences Meeting 2006 - Reno, NV, United States
Duration: Jan 9 2006Jan 12 2006

Publication series

NameCollection of Technical Papers - 44th AIAA Aerospace Sciences Meeting


Other44th AIAA Aerospace Sciences Meeting 2006
Country/TerritoryUnited States
CityReno, NV

ASJC Scopus subject areas

  • Space and Planetary Science
  • Aerospace Engineering


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