Numerical analysis of reaction-diffusion effects on species mixing rates in turbulent premixed methane-air combustion

Journal Article · Mon Mar 15 00:00:00 EDT 2010 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2009.11.007· OSTI ID:21285637

Richardson, E S; Grout, R W; Chen, J H ^[1]; Sankaran, R ^[2]

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1. Reacting Flow Research Department, Combustion Research Facility, Sandia National Laboratories, P.O. Box 969 MS 9051, Livermore, CA 94551-0969 (United States)
2. National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6008 (United States)

The scalar mixing time scale, a key quantity in many turbulent combustion models, is investigated for reactive scalars in premixed combustion. Direct numerical simulations (DNS) of three-dimensional, turbulent Bunsen flames with reduced methane-air chemistry have been analyzed in the thin reaction zones regime. Previous conclusions from single step chemistry DNS studies are confirmed regarding the role of dilatation and turbulence-chemistry interactions on the progress variable dissipation rate. Compared to the progress variable, the mixing rates of intermediate species is found to be several times greater. The variation of species mixing rates are explained with reference to the structure of one-dimensional premixed laminar flames. According to this analysis, mixing rates are governed by the strong gradients which are imposed by flamelet structures at high Damkoehler numbers. This suggests a modeling approach to estimate the mixing rate of individual species which can be applied, for example, in transported probability density function simulations. Flame-turbulence interactions which modify the flamelet based representation are analyzed. (author)

• OSTI ID: 21285637
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 3 Vol. 157; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
AIR
COMBUSTION
COMBUSTION KINETICS
COMPUTERIZED SIMULATION
DIFFUSION
LAMINAR FLAMES
MATHEMATICAL MODELS
METHANE
MIXING
PROBABILITY DENSITY FUNCTIONS
Premixed flames
SCALARS
Scalar dissipation rate
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
Turbulent mixing time scale
VARIATIONS