Multiple mapping conditioning for flames with partial premixing

Journal Article · Wed Oct 15 04:00:00 EDT 2008 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2008.03.012· OSTI ID:21116107

Kronenburg, A; Cleary, M J ^[1]

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1. Department of Mechanical Engineering, Imperial College London, Exhibition Rd, London, SW7 2AZ (United Kingdom)

Fully closed multiple mapping conditioning (MMC) is used to model partially premixed flames in homogeneous, isotropic decaying turbulence where the partial premixing is caused by local extinction and reignition phenomena. Two reference variables that represent mixing and reaction progress, such as mixture fraction and sensible enthalpy, are used to emulate turbulent scalar fluctuations. Local extinction is achieved by a priori coupling between scalar dissipation and temperature fluctuations via a correlation function that is based on the conditionally averaged sensible enthalpy at stoichiometric composition. The proposed model provides closures for the joint PDF of mixture fraction and sensible enthalpy, for the conditional variance equation of a reactive scalar, and for the doubly conditioned dissipation terms. Model results are compared with DNS in three flame cases with varying levels of local extinction, up to global extinction. The joint PDF predicted by MMC is in fair agreement with DNS. It constitutes, however, a clear improvement over conventional models using preassumed distribution functions for the PDFs. The doubly conditioned dissipation terms are modeled well and the results for all major chemical species are in good agreement with DNS. Predictions for intermediate species are also satisfactory. (author)

• OSTI ID: 21116107
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 155; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CORRELATION FUNCTIONS
COUPLING
DISTRIBUTION FUNCTIONS
ENTHALPY
FLAME EXTINCTION
FLAMES
FLUCTUATIONS
IGNITION
MAPPING
MATHEMATICAL MODELS
MIXING
MIXTURES
Multiple mapping conditioning
PROBABILITY DENSITY FUNCTIONS
REACTION INTERMEDIATES
SCALARS
STOICHIOMETRY
TURBULENCE