The nature of coherent deflagrations

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The nature of coherent deflagrations in an enclosure, vented into the atmosphere, is analysed. Experimental observations in an empty 547-m3 vented enclosure of the SOLVEX programme are analysed by means of large eddy simulations (LES). The LES model is based on the renormalization group theory and the dilution of the methane-air mixture, as it flows out of the vent, is taken into account. A comparison between simulated and experimental pressure transients and, the dynamics of the propagating flame front has given an insight into the nature of the complex simultaneous interactions between flow, turbulence and combustion inside the enclosure and in expelled gases. LES processing of experimental data unveiled that the substantial intensification of premixed combustion occurs only outside the enclosure , leading to a steep coherent pressure rise in both the internal and the external deflagrations. The external explosion does not affect burning rate inside the enclosure. The LES model shows excellent agreement with experimental pressures measured at different locations within and outside the enclosure, up to the point where the flame reaches the shear layers at the edge of the external jet. The modelling of the subsequent combustion required the use of one additional ad hoc parameter. It is suggested that this quantity is necessary to account for the unresolved subgrid scale increase of flame surface density in these highly turbulent layers. The mechanism of combustion intensification in this region is discussed.
LanguageEnglish
Title of host publicationUnknown Host Publication
Pages35-44
Number of pages10
Publication statusPublished - Oct 2004
EventFifth International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions - Cracow, Poland
Duration: 1 Oct 2004 → …

Conference

ConferenceFifth International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions
Period1/10/04 → …

Fingerprint

deflagration
enclosure
large eddy simulation
flames
transient pressures
burning rate
group theory
vents
flame propagation
shear layers
dilution
explosions
methane
turbulence
atmospheres
air
gases

Cite this

Molkov, V., Makarov, D., & Puttock, J. (2004). The nature of coherent deflagrations. In Unknown Host Publication (pp. 35-44)
Molkov, Vladimir ; Makarov, Dmitriy ; Puttock, J. / The nature of coherent deflagrations. Unknown Host Publication. 2004. pp. 35-44
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abstract = "The nature of coherent deflagrations in an enclosure, vented into the atmosphere, is analysed. Experimental observations in an empty 547-m3 vented enclosure of the SOLVEX programme are analysed by means of large eddy simulations (LES). The LES model is based on the renormalization group theory and the dilution of the methane-air mixture, as it flows out of the vent, is taken into account. A comparison between simulated and experimental pressure transients and, the dynamics of the propagating flame front has given an insight into the nature of the complex simultaneous interactions between flow, turbulence and combustion inside the enclosure and in expelled gases. LES processing of experimental data unveiled that the substantial intensification of premixed combustion occurs only outside the enclosure , leading to a steep coherent pressure rise in both the internal and the external deflagrations. The external explosion does not affect burning rate inside the enclosure. The LES model shows excellent agreement with experimental pressures measured at different locations within and outside the enclosure, up to the point where the flame reaches the shear layers at the edge of the external jet. The modelling of the subsequent combustion required the use of one additional ad hoc parameter. It is suggested that this quantity is necessary to account for the unresolved subgrid scale increase of flame surface density in these highly turbulent layers. The mechanism of combustion intensification in this region is discussed.",
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Molkov, V, Makarov, D & Puttock, J 2004, The nature of coherent deflagrations. in Unknown Host Publication. pp. 35-44, Fifth International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions, 1/10/04.

The nature of coherent deflagrations. / Molkov, Vladimir; Makarov, Dmitriy; Puttock, J.

Unknown Host Publication. 2004. p. 35-44.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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T1 - The nature of coherent deflagrations

AU - Molkov, Vladimir

AU - Makarov, Dmitriy

AU - Puttock, J.

PY - 2004/10

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AB - The nature of coherent deflagrations in an enclosure, vented into the atmosphere, is analysed. Experimental observations in an empty 547-m3 vented enclosure of the SOLVEX programme are analysed by means of large eddy simulations (LES). The LES model is based on the renormalization group theory and the dilution of the methane-air mixture, as it flows out of the vent, is taken into account. A comparison between simulated and experimental pressure transients and, the dynamics of the propagating flame front has given an insight into the nature of the complex simultaneous interactions between flow, turbulence and combustion inside the enclosure and in expelled gases. LES processing of experimental data unveiled that the substantial intensification of premixed combustion occurs only outside the enclosure , leading to a steep coherent pressure rise in both the internal and the external deflagrations. The external explosion does not affect burning rate inside the enclosure. The LES model shows excellent agreement with experimental pressures measured at different locations within and outside the enclosure, up to the point where the flame reaches the shear layers at the edge of the external jet. The modelling of the subsequent combustion required the use of one additional ad hoc parameter. It is suggested that this quantity is necessary to account for the unresolved subgrid scale increase of flame surface density in these highly turbulent layers. The mechanism of combustion intensification in this region is discussed.

M3 - Conference contribution

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Molkov V, Makarov D, Puttock J. The nature of coherent deflagrations. In Unknown Host Publication. 2004. p. 35-44