The compositional structure and the effects of exothermicity in a nonpremixed planar jet flame
- State Univ. of New York, Buffalo, NY (United States). Dept. of Mechanical and Aerospace Engineering
Results are presented of direct numerical simulation (DNS) of a randomly perturbed compressible, spatially developing two-dimensional planar jet under the influence of a finite rate chemical reaction of the type F + O [r arrow] Product. The objectives of the simulations are to assess the compositional structure of the flame and to determine the influence of reaction exothermicity by means of statistical sampling of the DNS generated data. These results indicate that the Damkoehler number is an important parameter in determining the statistical composition of the reacting field and that the results are not very sensitive to the mechanism by which this parameter is varied. It is demonstrated that as the intensity of mixing is increased and the effect of finite rate chemistry is more pronounced, the magnitudes of the ensemble mean and variance of the product mass fraction decrease and those of the reactants' mass fraction increase. Also, at higher mixing rates the joint probability density functions of the reactants' mass fractions shift towards higher values within the composition domain, indicating a lower reactedness. The DNS-generated data are also utilized to examine the applicability of the laminar diffusion flamelet model in predicting the rate of the reactant conversion with finite rate chemistry. This examination indicates that the performance of the model is improved as the value of the Damkoehler number is increased. Finally, the simulated results suggest that in the setting of a turbulent flame, the effect of the heat liberated by the chemical reaction is to increase the rate of reactant conversion. This finding is different from those of earlier DNS results and laboratory investigations that indicate a suppressed chemical reaction with increasing heat release.
- OSTI ID:
- 5982747
- Journal Information:
- Combustion and Flame; (United States), Journal Name: Combustion and Flame; (United States) Vol. 94:3; ISSN CBFMAO; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
CHEMICAL COMPOSITION
CHEMICAL REACTION KINETICS
COMBUSTION KINETICS
COMPRESSIBILITY
DIFFUSION
DISTRIBUTION
ENERGY TRANSFER
FLAMES
FLUID FLOW
HEAT TRANSFER
JETS
KINETICS
LAMINAR FLOW
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MIXING
MORPHOLOGY
REACTION KINETICS
TURBULENT FLOW
TWO-DIMENSIONAL CALCULATIONS