On the structural sensitivity of purely strained planar premixed flames to strain rate variations

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Combustion and Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(94)90204-6· OSTI ID:7084279

Law, C K; Sung, C J; Yu, G ^[1]; Axelbaum, R L ^[2]

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1. Princeton Univ., NJ (United States). Dept. of Mechanical and Aerospace Engineering
2. Washington Univ., St. Louis, MO (United States). Dept. of Mechanical Engineering

The effects of aerodynamic straining on the structure and response of adiabatic, unrestrained, equidiffusive, planar premixed flames were experimentally and computationally studied via the counterflow, twin-flame configuration formed by oppositely directed identical jets of nitrogen-diluted, near-stoichiometric methane/air mixtures. Experimentally, the velocity, temperature and major species concentration profiles were determined as functions of the applied strain rate by using LDV and spontaneous Raman scattering. Computationally, the experimental situation was simulated with detailed reaction mechanisms and transport properties. Both the experimental and computational results show that the temperature and species structure of the flame in the direction normal to the flame surface remains largely similar in response to variations in strain rate as long as the flame is sufficiently far away from the stagnation surface so that incomplete reaction is minimal. These results substantiate the concepts that the scalar structure of the flame, and thereby the flame thickness, are insensitive to strain rate variations for these purely strained flames, and that these flames cannot be extinguished by straining alone. The computed results are further shown to agree quantitatively with the experimental data, hence supporting the usefulness of the computational model for the simulation of strained flames. Implications of present findings on the concept of the local flow time, the extinction of strained flames, the modeling of turbulent flames through the concept of laminar flamelets, and flame stabilization and blowoff, are discussed.

• OSTI ID: 7084279
• Journal Information: Combustion and Flame; (United States), Journal Name: Combustion and Flame; (United States) Vol. 98:1-2; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
034000 -- Natural Gas-- Combustion
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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ALKANES
CHEMICAL REACTION KINETICS
COMBUSTION KINETICS
FLAMES
FLUID FLOW
HYDROCARBONS
KINETICS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
METHANE
MORPHOLOGY
ORGANIC COMPOUNDS
REACTION KINETICS
STRAIN RATE
TURBULENT FLOW
VELOCIMETERS