Finite-rate chemistry and transient effects in Direct Numerical Simulations of turbulent non-premixed flames
- Colorado Univ., Boulder, CO (United States). Dept. of Mechanical Engineering
- Sandia National Labs., Livermore, CA (United States)
- Institut de Mecanique des Fluides, Numeriques (France)
Three-dimensional Direct Numerical Simulations (DNS) of turbulent non-premixed 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 chosen to model methane-air combustion, and (2) a two-step reaction model to simulate radical production and consumption and to compare against the single-step model. The model problem consists of the interaction between an initially unstrained 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 with 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 the observed high concentrations of reaction intermediates.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); National Aeronautics and Space Administration, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 10115417
- Report Number(s):
- SAND-94-8507C; CONF-940838-5; ON: DE94005250
- Resource Relation:
- Conference: 25. combustion symposium,Irvine, CA (United States),1 Aug 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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