Stability of a deflagration front in compressible media

Ni, Angxiu; Goel, B.

doi:10.1007/bf01003553

Cited by 1 publication

(6 citation statements)

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“…Hence the structure of the fast combustion front is open to a certain extent. Ni & Goel (1995) have explored this matter by investigating the perturbation of the complete system of Euler equations ahead and behind a fast subsonic (compressible) front including the Rankine-Hugoniot jump conditions. With entropy no longer approximately conserved across the front due to the high speed, the perturbation in pressure just before and after is now also not the same, but one can obtain a connection between the amplitude of (large-length-scale (N M −1 )) acoustic disturbances before and behind the front, which has (as a parameter) the dependence of burning rate on pressure.…”

Section: Compressible Subsonic Deflagrations and Large-length-scale (N M −1 ) Acoustic Interactionsmentioning

confidence: 99%

“…In the same spirit, we apply the theory to fast subsonic deflagrations (where the structure is not necessarily known) in order to get some estimate as to regions of acoustic resonance. What follows is a brief summary of the main results, with an important derivation of the resonance frequency condition for fast compressible combustion waves using the approach of Ni & Goel (1995).…”

Section: Compressible Subsonic Deflagrations and Large-length-scale (N M −1 ) Acoustic Interactionsmentioning

confidence: 99%

“…(5.16) it can be shown (Ni & Goel 1995) that for the absolute value of the reflection coefficients in cases (a) and (b) above to be greater than one (and consequently to have acoustic growth), the mass burning rate sensitivity to pressure must lie in the following range: ) is used because it can be shown that, to leading order, ℵ is equivalent to the mass flux derivative with pressure times heat release. Thus…”

Section: (A) One-dimensional Acoustic Instability Of a Fast Compressible Combustion Frontmentioning

confidence: 99%

“…In general, for laminar low-speed flames, the value of ℵ is too small, but as pointed out by Ni & Goel (1995), a fast turbulent flame will quite readily meet the criteria (5.21) and (5.22) for resonance. Thus the above criteria are important for acoustic growth.…”

Section: (A) One-dimensional Acoustic Instability Of a Fast Compressible Combustion Frontmentioning

confidence: 99%

“…Thus the last part of this work considers acoustics interacting with a fast (but still subsonic) combustion front. The significant work of Ni & Goel (1995) has led the way in this interesting development. The combustion front, though one dimensional, may in fact be turbulent in its structure, and the unsteady pressure disturbances are now characterized by a long length-scale.…”

Section: Introductionmentioning

confidence: 99%

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Deflagration fronts and compressibility

McIntosh

1999

Philosophical Transactions of the Royal Society of London. Seri

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This paper seeks to bring together a number of results pertaining to the interaction of pressure waves with premixed combustion fronts. Some of the earlier results concerning low-speed flames and acoustics are set in context with some of the later work, which is still being developed and which takes compressibility into account to a much greater extent. The interaction of low-speed flames with steep pressure drops shows a possible mechanism for flame extinction, and the interaction with steep pressure rises indicates conditions for rapid flame acceleration to fast convection-reaction driven deflagrations. This work demonstrates that the transient nature of fast flames, with their corresponding acoustic and reactive acoustic zones due to temperature singularities (blow up) occurring near the driving piston of such deflagrations, is very sensitive to imposed pressure disturbances. In a separate section at the end of this paper, we address the question of the amplification of long-wavelength acoustic waves reflected from fast deflagrations, where the entropy change across such fronts is significant, but where the structure of the deflagration is uncertain.

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Section: Compressible Subsonic Deflagrations and Large-length-scale (N M −1 ) Acoustic Interactionsmentioning

confidence: 99%

Section: Compressible Subsonic Deflagrations and Large-length-scale (N M −1 ) Acoustic Interactionsmentioning

confidence: 99%

Section: (A) One-dimensional Acoustic Instability Of a Fast Compressible Combustion Frontmentioning

confidence: 99%

Section: (A) One-dimensional Acoustic Instability Of a Fast Compressible Combustion Frontmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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