Results 1 to 10 of about 28,542 (259)

Sound Generated by Cellular Flames

1991
It has been observed that flames propagating in tubes can spontaneously produce acoustic oscillations (Mallard and le Chatelier1). Rayleigh2 gave a general criterion for acoustic amplification by any local heat source: When heat is released locally and periodically in a gaseous medium, an acoustic oscillation is amplified if the oscillating components ...
Pierre Pelcé, Daniel Rochwerger
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The cellular nature of hydrodynamic flame instability

Physica D: Nonlinear Phenomena, 1990
Abstract The nonlinear evolution of a weakly perturbed planar flame under the influence of the Landau-Darrieus instability is studied numerically. It is shown that in sufficiently small-scale systems spontaneous instability appears in the guise of a cusp-shape flame.
Gutman, S., Sivashinsky, G. I.
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On curved cellular flames

2008
Laminar premixed flames exhibit cellular instabilities for sufficiently small Lewis-numbers. In the present article we study a modified Kuramoto-Sivashinsky-equation describing curved, cellular flames near the instability threshold. Pattern formation is strongly influenced by the sign of flame curvature.
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On transition to cellularity in expanding spherical flames

Journal of Fluid Mechanics, 2007
The instant of transition to cellularity of centrally ignited, outwardly propagating spherical flames in a reactive environment of fuelx–oxidizer mixture, at atmospheric and elevated pressures, was experimentally determined using high-speed schlieren imaging and subsequently interpreted on the basis of hydrodynamic and diffusional–thermal instabilities.
G. JOMAAS, C. K. LAW, J. K. BECHTOLD
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A theoretical derivation of cellular structures of flames

Zeitschrift f�r Physik B Condensed Matter, 1985
Using an equation for the formation of flame fronts derived by Sivashinsky and augmented by an additional term describing buoyancy effects we present an analytical treatment of the formation of cellular structures of flames formed by plane burners. In particular we find rectangular and square patterns.
B. Schnaufer, H. Haken
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Self-fragmentation of nonadiabatic cellular flames

Combustion and Flame, 1997
A simple thermal-diffusive model for premixed flames with radiative heat losses is studied numerically. In accordance with previous analytical predictions, it is shown that cellular flames occurring in low Lewis number premixtures can propagate with heat-loss rates greater than the maximum that extinguishes the planar flame.
L. Kagan, G. Sivashinsky
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Gravitational effects on cellular flame structure

Symposium (International) on Combustion, 1991
An experimental investigation has been conducted of the effect of gravity on the structure of downwardly propagating, cellular premixed propane-oxygen-nitrogen flames anchored on a water-cooled porous-plug burner. The flame is subjected to microgravity conditions in the NASA Lewis 2.2-second drop tower, and flame characteristics are recorded on high ...
C.M. Dunsky, A.C. Fernandez-Pello
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Detailed numerical simulations of cellular flames

Symposium (International) on Combustion, 1989
Time-dependent, two-dimensional simulations of perturbed premixed laminar flames have been used to study the development of cellular structures in rich and lean hydrogen flames. The model includes detailed hydrogen-oxygen combustion with 24 elementary reactions of eight reactive species and a nitrogen diluent, molecular diffusion of all species ...
G. Patnaik, K. Kailasanath, E.S. Oran, K.J. Laskey   +3 more
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On disintegration of near-limit cellular flames

Physics Letters A, 2003
A strongly non-linear geometrically-invariant model for the dynamics of near-limit cellular flame is proposed, where the flame evolution is governed by a system of equations for the flame interface and its temperature. The model generalizes its earlier weakly non-linear version pertinent to a mildly perturbed planar flame.
Michael L Frankel, Peter V Gordon, Gregory I Sivashinsky   +2 more
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Expanding Flames May Delay the Transition to Cellular Structures

SIAM Journal on Applied Mathematics, 1984
We derive a general equation for the evolution of flame fronts in weakly nonuniform flows. The equation is restricted to a particular range of Lewis numbers and describes the transition to cellular structures. This transition is analyzed for an expanding curved flame.
Matalon, Moshe, Erneux, Thomas
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