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Page d'accueil ICHMT DL Année en cours Archives Comité de direction Centre international pour le transfert de chaleur et de masse


DOI: 10.1615/ICHMT.2008.CHT.1820
page 11

Makoto Sato
Department of Mechanical and Aerospace Engineering, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8850, Japan

Shingo Matsuura
Department of Mechanical and Aerospace Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan

Mamoru Tanahashi
Department of Mechanical and Aerospace Engineering Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan

Toshio Miyauchi
Dept. Mechanical and Aerospace Eng., Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan; Organization for the Strategic Coordination of Research and Intellectual Properties Meiji University 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa, Japan


Direct numerical simulations (DNS) of ignition and propagation of turbulent premixed flames in homogeneous isotropic turbulence have been conducted for hydrogen/air, methane/air and n-heptane/air mixture to investigate effects of turbulence on ignition and propagation process. A detailed kinetic mechanism which includes 12 reactive species and 27 elementary reactions is used for hydrogen/air mixture and that includes 49 reactive species and 279 elementary reactions is used for methane/air mixture and a reduced kinetic mechanism which includes 38 reactive species and 61 elementary reactions is used for n-heptane/air mixture. In the ignition process, the high temperature region is stretched and its evolution is disturbed by surrounding eddies. This impediment leads to a significant ignition delay compared with the laminar case. Even if turbulent field is statistically same, the ignition delay significantly depends on local characteristics of turbulence. Ignition delay tends to increase with the increase of mean strain rate in the initial high temperature region. If the high temperature region is separated by the strong eddies in the initial process, the ignition of the mixture delays further. In the propagation process, the flame front is stretched and disturbed its evolution by strong eddies, and the flame propagates along the edge of eddies. The flame fronts that are enclosed by the burnt gas shows high heat release rate. This structure and increasing of flame front area enhance turbulent burning velocity. The flame propagation behaviours are different for fuel. Especially, strong stretching by eddy induces local extinction for methane cases, and the production of NO2 is enhanced in these regions. Pressure effects are also investigated for methane/air mixture.

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