A Study of the Laminar Flame Tip and Implications for Premixed Turbulent Combustion

Abstract Flame surface curvature is a significant geometrical parameter that affects the structure and propagation of premixed laminar and turbulent flames. In this study, the flame tip of a two-dimensional laminar Bunsen burner is investigated using a quasi-one dimensional model, direct numerical simulations and experimental results. The laminar flame tip is a simple prototype of curved flamelets embedded in a turbulent flow field. It is shown that two characteristic flame speeds are necessary to give a local description of a given flamelet: the consumption speed associated with the structure of the reaction zone, and the displacement speed of the flame front relative to the unburned flow. The quasi-one dimensional model shows that three different mechanisms affect the displacement speed of a curved flame in a non-uniform flow field: a chemical mechanism associated with the expansion of the reaction zone structure, a hydrodynamic mechanism due to isothermal area modification by lateral flow divergence an...

[1]  J. Shwartz,et al.  A MODEL OF TWO-DIMENSIONAL FLOW EFFECTS IN LASER SUPPORTED COMBUSTION WAVES AND LAMINAR FLAMES , 1983 .

[2]  Francis E. Fendell,et al.  Asymptotic Analysis of Laminar Flame Propagation for General Lewis Numbers , 1970 .

[3]  P. Clavin,et al.  Premixed flames in large scale and high intensity turbulent flow , 1983 .

[4]  Jun'ichi Sato,et al.  Effects of lewis number on extinction behavior of premixed flames in a stagnation flow , 1982 .

[5]  Forman A. Williams,et al.  Structure of laminar flamelets in premixed turbulent flames , 1982 .

[6]  Chung King Law,et al.  Dynamics of stretched flames , 1984 .

[7]  Paul A. Libby,et al.  Passage Times and Flamelet Crossing Frequencies in Premixed Turbulent Combustion , 1986 .

[8]  Forman A. Williams,et al.  Effects of molecular diffusion and of thermal expansion on the structure and dynamics of premixed flames in turbulent flows of large scale and low intensity , 1982, Journal of Fluid Mechanics.

[9]  D. Mikolaitis.  The interaction of flame curvature and stretch, part 1: The concave premixed flame , 1984 .

[10]  Forman A. Williams,et al.  Strained premixed laminar flames with nonunity Lewis numbers , 1983 .

[11]  N. Peters.  Laminar flamelet concepts in turbulent combustion , 1988 .

[12]  F. E. Marble,et al.  The coherent flame model for turbulent chemical reactions. Final report 1 Mar 75--31 Jan 77 , 1977 .

[13]  Bernard J. Matkowsky,et al.  Flames as gasdynamic discontinuities , 1982, Journal of Fluid Mechanics.

[14]  Geoffrey Searby,et al.  Direct and indirect measurements of Markstein numbers of premixed flames , 1990 .

[15]  W. Ashurst.  Vortex simulation of unsteady wrinkled laminar flames , 1987 .

[16]  G. Sivashinsky.  Structure of Bunsen flames , 1975 .

[17]  Thierry Poinsot,et al.  Flame Stretch and the Balance Equation for the Flame Area , 1990 .

[18]  G. H. Markstein,et al.  Experimental and Theoretical Studies of Flame-Front Stability , 1951 .

[19]  F. C. Gouldin,et al.  Chemical Closure Model for Fractal Flamelets , 1989 .

[20]  C. Law,et al.  Flame curvature and preferential diffusion in the burning intensity of bunsen flames , 1988 .

[21]  J. Buckmaster,et al.  The fluid mechanics of flame tips , 1983, Journal of Fluid Mechanics.

[22]  Chung King Law,et al.  An integral analysis of the structure and propagation of stretched premixed flames , 1988 .

[23]  J. Sethian,et al.  Fronts propagating with curvature-dependent speed: algorithms based on Hamilton-Jacobi formulations , 1988 .

[24]  Chung King Law,et al.  An invariant derivation of flame stretch , 1984 .

[25]  T. Poinsot.  Boundary conditions for direct simulations of compressible viscous flows , 1992 .

[26]  C. Law,et al.  On the Opening of Premixed Bunsen Flame Tips , 1982 .

[27]  C. Law,et al.  Effects of preferential diffusion on the burning intensity of curved flames , 1985 .

[28]  Moshe Matalon,et al.  On Flame Stretch , 1983 .

[29]  D. Mikolaitis.  The interaction of flame curvature and stretch, part 2: The convex premixed flame , 1984 .

[30]  M. Smooke,et al.  Extinction of Strained Premixed Laminar Flames With Complex Chemistry , 1987 .

[31]  G. Sivashinsky,et al.  On a distorted flame front as a hydrodynamic discontinuity , 1976 .

[32]  Thierry Poinsot,et al.  Quenching processes and premixed turbulent combustion diagrams , 1991, Journal of Fluid Mechanics.

[33]  Frediano V. Bracco,et al.  Fractals and turbulent premixed engine flames , 1989 .

[34]  P. Libby,et al.  Premixed Laminar Flames with General Rates of Strain , 1987 .

[35]  John Buckmaster,et al.  A Mathematical Description of Open and Closed Flame Tips , 1979 .

[36]  Hiroshi Tsuji,et al.  Structure and extinction of near-limit flames in a stagnation flow , 1982 .

[37]  Mitchell D. Smooke,et al.  Solution of burner-stabilized premixed laminar flames by boundary value methods , 1982 .

[38]  F. E. Marble,et al.  The Effect of Strain Rate on a Premixed Laminar Flame , 1986 .

[39]  G. Dixon-Lewis,et al.  Flame modelling and burning velocity measurement , 1982 .

[40]  S. Candel,et al.  A nonlinear model for ducted flame combustion instabilities , 1988 .