Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-25T20:27:31.204Z Has data issue: false hasContentIssue false

Flames as gasdynamic discontinuities

Published online by Cambridge University Press:  20 April 2006

M. Matalon
Affiliation:
Department of Engineering Sciences and Applied Mathematics, The Technological Institute, Northwestern University, Evanston, Illinois 60201
B. J. Matkowsky
Affiliation:
Department of Engineering Sciences and Applied Mathematics, The Technological Institute, Northwestern University, Evanston, Illinois 60201

Abstract

Early treatments of flames as gasdynamic discontinuities in a fluid flow are based on several hypotheses and/or on phenomenological assumptions. The simplest and earliest of such analyses, by Landau and by Darrieus prescribed the flame speed to be constant. Thus, in their analysis they ignored the structure of the flame, i.e. the details of chemical reactions, and transport processes. Employing this model to study the stability of a plane flame, they concluded that plane flames are unconditionally unstable. Yet plane flames are observed in the laboratory. To overcome this difficulty, others have attempted to improve on this model, generally through phenomenological assumptions to replace the assumption of constant velocity. In the present work we take flame structure into account and derive an equation for the propagation of the discontinuity surface for arbitrary flame shapes in general fluid flows. The structure of the flame is considered to consist of a boundary layer in which the chemical reactions occur, located inside another boundary layer in which transport processes dominate. We employ the method of matched asymptotic expansions to obtain an equation for the evolution of the shape and location of the flame front. Matching the boundary-layer solutions to the outer gasdynamic flow, we derive the appropriate jump conditions across the front. We also derive an equation for the vorticity produced in the flame, and briefly discuss the stability of a plane flame, obtaining corrections to the formula of Landau and Darrieus.

Type
Research Article
Copyright
© 1982 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Barenblatt, G. I., Zeldovich, Y. B. & Istratov, A. G. 1962 On diffusional thermal instability of laminar flame. Prikl. Mekh. Tekh. Fiz. 2, 21.Google Scholar
Buckmaster, J. D. 1979 The quenching of two dimensional premixed flames. Acta Astronautica 6, 741.Google Scholar
Clavin, P. & Williams, F. A. 1982 Effects of molecular diffusion and of thermal expansion on the structure and dynamics of premixed flames in turbulent flows of large scales and low intensity. J. Fluid Mech. 116, 251.Google Scholar
Darrieus, G. 1945 Propagation d'un front de flamme. Presented at Le congres de Mecanique Appliquee (unpublished).
Eckhaus, W. 1961 Theory of flame-front stability. J. Fluid Mech. 10, 80.Google Scholar
Emmons, H. W. 1958 Flow discontinuities associated with combustion. In Fundamentals of Gas Dynamics (ed. H. W. Emmons), p. 584. Princeton University Press.
Frankel, M. L. & Sivashinsky, G. I. 1982 The effect of viscosity on hydro-dynamic stability of a plane flame front. Submitted for publication.
Harten, A. Van & Matkowsky, B. J. 1982 A new model in flame theory. SIAM J. Appl. Math. (to appear).
Karlovitz, B., Denniston, D. W., Knapschaefer, D. H. & Wells, F. E. 1953 Studies on turbulent flames. in Proc. 4th Int. Symp. on Combustion, p. 613. William & Wilkins.
Landau, L. D. 1944 On the theory of slow combustion. Acta Physicochimica URSS 19, 77.Google Scholar
Lewis, B. & Elbe von, G. 1967 Combustion Flames and Explosion of Gases, 2nd edn. Academic.
Markstein, G. H. 1951 Experimental and theoretical studies of flame front stability. J. Aero. Sci. 18, 199.Google Scholar
Markstein, G. H. 1964 Nonsteady Flame Propagation. Pergamon.
Matkowsky, B. J. & Sivashinsky, G. I. 1979 An asymptotic derivation of two models in flame theory associated with the constant density approximation. SIAM J. Appl. Math. 37, 686.Google Scholar
Pelce, P. & Clavin, R. 1982 Influence of hydrodynamics and diffusion upon the stability limits of laminar premixed flames. J. Fluid Mech. 124, 219.Google Scholar
Sivashinsky, G. I. 1976 On a distorted flame front as a hydrodynamic discontinuity. Acta Astronautica 3, 889.Google Scholar