Dynamics of Water Droplets in a Counterflow Field and their Effect on Flame Extinction

Lentati, A.M.; Chelliah, Harsha K.

doi:10.1016/s0010-2180(97)00355-6

Cited by 91 publications

(49 citation statements)

References 12 publications

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“…This permitted studies of large droplets by Prasad et al [9]. The nonmonotonic behavior in droplet concentration (at extinction) with drop size in 2-dimensional, low strain, co-flow flame appears to be qualitatively similar to the relationship between extinction strain rate and drop size predicted for 1-dimensional, highly strained, opposed jet flame considered by Lentati and Chelliah [24,25]. Further work is needed to establish a quantitative relationship between these two works.…”

Section: Resultsmentioning

confidence: 59%

“…This is likely because transport effects dominate in co-flow flames and chemical effects become significant only very close to the extinction point. Even in counterflow diffusion flames, where the flame is highly stretched and the flame is close to extinction to begin with, the chemical effects are found to be insignificant [24,25].…”

Section: Resultsmentioning

confidence: 98%

“…The droplet is assumed to be spherical and the internal gradients of momentum and energy are neglected in view of extremely small size range considered in the computations. This assumption is typically used for water [9,22,24,25,28,32]. Liquid water has five times higher thermal conductivity than a typical hydrocarbon liquid such as heptane.…”

Section: Theoreticalmentioning

confidence: 99%

“…As the air velocity is increased to 170 cm/sec, the computations show that the extinction concentration is less dependent on the drop size. Lentati and Chelliah [24,25] modeled extinction of one-dimensional, counter-flow, diffusion flames by water droplets, and showed that the physical effects dominate over any chemical effects. In the counter-flow geometry, large jet velocities of air and methane (order of 2 m/sec) are employed.…”

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confidence: 99%

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Extinction Dynamics of a Co-flow Diffusion Flame by Very Small Water Droplets Injected into the Air Stream

Ananth¹,

Mowrey²

2008

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Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Computations are performed to examine the effectiveness of mono-disperse water droplets in extinguishing a co-flow, propane diffusion flame by injecting the droplets into the air stream. The calculations show that the droplets entrained into the reaction kernel at the flame base are crucial for extinction. The reaction kernel detaches from the burner rim and blows-off when the droplet concentration is increased to a critical value (extinction concentration). At the critical value, the maximum chain-branching reaction (H2+O=OH+H) rate in the reaction kernel was found to be reduced by a factor of 5 in our computations. A large decrease in the reaction rate indicates that the maximum heat generations rate and Damkholer number are too low to sustain the flame, and cause the flame blow-off. Large drops are more effective than small drops, and the extinction concentration of water increases from 10.5% to 15% by mass as the size is reduced from 32 to 4 micro m. As the droplet size is increased further (>32 micro m), the trend will reverse as the evaporation rates get too small despite increased penetration of flame core by the drops. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S ACRONYM(S) 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S REPORT NUMBER(S) 28-07-2008Memorandum Report

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Section: Resultsmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 98%

Section: Theoreticalmentioning

confidence: 99%

mentioning

confidence: 99%

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Extinction Dynamics of a Co-flow Diffusion Flame by Very Small Water Droplets Injected into the Air Stream

Ananth¹,

Mowrey²

2008

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“…The heat transfer mechanisms between a methane-air flame front and a water spray or mist have been fully described by Parra et al [4]. Besides the flame extinction mechanisms [5,2,6] and the mitigation effects of the spray [7][8][9][10][11][12][13] are characterized for methane-or propane-air flame. The fine analysis of the above topics is very limited in the literature and some discrepancies are observed between the experimental data and numerical results.…”

Section: Lumped Parameter Analysis: Hydrogen Combustion Under Liquid mentioning

confidence: 99%

On the use of spray systems: An example of R&D work in hydrogen safety for nuclear applications

Joseph-Auguste

Cheikhravat

Chaumeix

et al. 2009

International Journal of Hydrogen Energy

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Explosion mitigation of methane–air mixture in combined application of HFC‐227ea/CO₂ and ultrafine water mist in the pipeline

Yang,

Jia,

et al. 2023

Process Safety Progress

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In order to reduce the power of methane explosion in natural gas pipelines and effectively improve the explosion suppression efficiency of a single explosion suppressant, we carry out the explosion suppression of HFC‐227ea/carbon dioxide mixed gas as well as mixed gas/ultrafine water mist through a self‐built methane explosion suppression experimental platform. Based on the changes in parameters such as explosion overpressure, flame propagation velocity, and flame propagation structure, the coupling mechanism of methane explosion suppression between mixed gases and between mixed gases and ultrafine water mist is revealed, which provides scientific support for promoting the development of methane explosion suppression technology. The experimental results show that when the mixed gas HFC‐227ea/carbon dioxide and ultrafine water mist synergistically suppresses methane explosion, the addition of the mixed gas can effectively improve the suppression effect of ultrafine water mist on methane explosion.

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Dynamics of Water Droplets in a Counterflow Field and their Effect on Flame Extinction

Cited by 91 publications

References 12 publications

Extinction Dynamics of a Co-flow Diffusion Flame by Very Small Water Droplets Injected into the Air Stream

Extinction Dynamics of a Co-flow Diffusion Flame by Very Small Water Droplets Injected into the Air Stream

On the use of spray systems: An example of R&D work in hydrogen safety for nuclear applications

Explosion mitigation of methane–air mixture in combined application of HFC‐227ea/CO₂ and ultrafine water mist in the pipeline

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Dynamics of Water Droplets in a Counterflow Field and their Effect on Flame Extinction

Cited by 91 publications

References 12 publications

Extinction Dynamics of a Co-flow Diffusion Flame by Very Small Water Droplets Injected into the Air Stream

Extinction Dynamics of a Co-flow Diffusion Flame by Very Small Water Droplets Injected into the Air Stream

On the use of spray systems: An example of R&D work in hydrogen safety for nuclear applications

Explosion mitigation of methane–air mixture in combined application of HFC‐227ea/CO2 and ultrafine water mist in the pipeline

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Product

Resources

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Explosion mitigation of methane–air mixture in combined application of HFC‐227ea/CO₂ and ultrafine water mist in the pipeline