Direct simulations of premixed turbulent flames with nonunity Lewis numbers

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Combustion and Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(93)90018-X· OSTI ID:6256126

Rutland, C J; Trouve, A ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Mechanical Engineering Stanford Univ., Stanford, CA (United States). Center for Turbulence Research

A principal effect of turbulence on premixed flames in the flamelet regime is to wrinkle the flame fronts. For nonunity Lewis numbers, Le [ne] 1, the local flame structure is altered in curved regions. This effect is examined using direct numerical simulations of three-dimensional isotropic turbulence with constant density, single-step Arrhenius kinetics chemistry. Simulations of Lewis numbers 0.8, 1.0, and 1.2 are compared. At the local level, curvature effects dominated changes to the flame structure while strain effects were insignificant. A strong Lewis-number-dependent correlation was found between surface curvature and the local flame speed. The correlation was positive for Le < 1 and negative for Le > 1. At the global level, strain-related effects were more significant than curvature effects. The turbulent flame speed changed significantly with Lewis number, increasing as Le decreased. This was found to be due to strain effect that have a nonzero mean over the flame surface, rather than to curvature effects that have a nearly zero mean. The mean product temperature was also found to vary with Lewis number, being higher for Le > 1 and lower for Le < 1.

• OSTI ID: 6256126
• Journal Information: Combustion and Flame; (United States), Vol. 94:1-2; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
FLAMES
MATHEMATICAL MODELS
MORPHOLOGY
COMBUSTION KINETICS
CORRELATIONS
FLOW RATE
STRAINS
TEMPERATURE DEPENDENCE
THREE-DIMENSIONAL CALCULATIONS
TURBULENT FLOW
CHEMICAL REACTION KINETICS
FLUID FLOW
KINETICS
REACTION KINETICS
400800* - Combustion
Pyrolysis
&amp; High-Temperature Chemistry