Autoignition and structure of nonpremixed CH{sub 4}/H{sub 2} flames: Detailed and reduced kinetic models
- Department of Mechanical and Aerospace Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260-4400 (United States)
The ignition dynamics and subsequent flame evolution of hydrogen-enriched methane mixtures are investigated numerically in a reacting vortex ring configuration. The CH{sub 4}/H{sub 2} combustion is studied using a detailed reaction mechanism (GRI-Mech v3.0) and two augmented reduced mechanisms (11-step and 12-step). The main objective of this study is to identify the extent that the current reduced mechanisms can go in replicating the dynamics of the ignition process and flame structure in an unsteady nonpremixed configuration. The parameters of the numerical simulations are adjusted such that flame ignition occurs during either the formation or the postformation of the ring. The quasi-steady state assumption for O in the 12-step reduced kinetic model leads to shorter ignition delay times than those in the other kinetic models. For formation-phase ignition runs, the flame structure near the stoichiometric region is captured well by the 12-step model compared to GRI-Mech 3.0. For postformation ignition runs, the 12-step model predicts larger heat release rates and main species mole fractions compared to GRI-Mech 3.0. The 11-step model predicts well the ignition delay time. At later times the fuel-rich side of the flame predicted by this reduced mechanism exhibits differences from the detailed model. Counterflow diffusion flame results are used to further compare the fuel-rich chemistry for the detailed and augmented reduced kinetic models.
- OSTI ID:
- 20685979
- Journal Information:
- Combustion and Flame, Vol. 144, Issue 1-2; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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