Finite-rate chemistry and transient effects in direct numerical simulations of turbulent nonpremixed flames
- Univ. of Colorado, Boulder, CO (United States). Center for Combustion Research
- Sandia National Labs., Livermore, CA (United States). Combustion Research Facility
- CORIA, Rouen (France). Laboratoire de Mechanique des Fluides Numeriques
Three-dimensional direct numerical simulations (DNS) of turbulent nonpremixed flames including finite-rate chemistry and heat release effects were performed. Two chemical reaction models were considered: (1) a single-step global reaction model in which the heat release and activation energy parameters are typical combustion applications, and (2) a two-step reaction model to stimulate radical production and consumption and to compare against the single-step model. The model problem consists of the interaction between an initially unstained laminar diffusion flame and a three-dimensional field of homogeneous turbulence. Conditions ranging from fast chemistry to the pure mixing limit were studied by varying a global Damkoehler number. Results suggest that turbulence-induced mixing acting along the stoichiometric line leads to a strong modification of the inner structure of the turbulent flame compared with a laminar strained flame, resulting in intermediate species concentrations well above the laminar prediction. This result is consistent the experimental observations. Comparison of the response of the turbulent flame structure due to changes in the scalar dissipation rate with a steady strained laminar flame reveals that unsteady strain rates experienced by the turbulent flame may be responsible for h3e observed high concentrations of reaction intermediates.
- OSTI ID:
- 116434
- Journal Information:
- Combustion and Flame, Vol. 102, Issue 3; Other Information: PBD: Aug 1995
- Country of Publication:
- United States
- Language:
- English
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