Raman spectroscopy measurements of flame quenching in a duct-type crevice

Fairchild, Paul W.; Fleeter, Rick; Fendell, Francis E.

doi:10.1016/s0082-0784(85)80491-4

Cited by 8 publications

(4 citation statements)

References 8 publications

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“…In wider channels burning persists even in the extreme case of isothermal walls maintained at the temperature of the fresh mixture, but the flame survives only near the center of the channel. The dead-space corresponding to the distance near the walls where the flame is quenched can be as large as 6l f in accord with experimentally reported values [80,81]. For sufficiently large values of d, the walls have a very limited influence on the flame, which then propagates at a speed close to the laminar flame speed.…”

Section: Flame Propagation In Channelssupporting

confidence: 85%

Flame dynamics

Matalon

2009

Proceedings of the Combustion Institute

203

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This lecture describes recent theoretical developments associated with the dynamics of flames, obtained primarily by exploiting the various temporal and length scales involved in the combustion process. In premixed flames the focus is on flame-flow interactions that occur during the nonlinear development of hydrodynamically unstable large-scale flames, or during the propagation of curved flames in two-dimensional channels. The second part of the paper deals with non-premixed and partially premixed flames, where the focus is on understanding the nature of diffusive-thermal instabilities including the effect of thermal expansion, and on stabilization mechanisms of edge flames, which possess characteristics of both premixed and diffusion flames. The results presented in this talk illustrate how simplified models, when analyzed to their extreme, yield predictions of qualitative nature with physical insight that have advanced our understanding of combustion. This insight can be used to guide the experimental efforts, explain observations and validate large-scale numerical simulations.

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Section: Flame Propagation In Channelssupporting

confidence: 85%

Flame dynamics

Matalon

2009

Proceedings of the Combustion Institute

203

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“…When su cient heat is removed through the walls, combustion cannot be selfsustained and thermal quenching occurs [27,28]. Radical quenching occurs through adsorption of radicals on the walls and subsequent recombination, which can lead to lack of homogeneous chemistry [29,30]. The small scales of micro-structured combustion systems make them signi cantly more prone to both quenching mechanisms due to the high surface area-to-volume ratios, which will lead to increased radical mass transfer and enhanced heat transfer from the ame to the walls.…”

Section: Introductionmentioning

confidence: 99%

WITHDRAWN: Scale effects on the combustion characteristics and flame stability of a methane-air mixture in continuous flow reactors

Chen

2022

Preprint

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A fundamental understanding of the stabilization mechanisms of a flame within very small spaces is of both fundamental and practical significance. This study relates to the scale effects on the combustion characteristics and flame stability of a methane-air mixture in continuous flow reactors. Computational fluid dynamics simulations are conducted to gain insights into reactor performance such as species concentrations, temperatures, and flames. The factors affecting combustion characteristics are determined for the continuous flow reactors. Particular focus is placed on determining essential factors that affect the performance of the continuous flow reactors. The results indicate that for large separation distances, the reaction rate is low and reaction spreads out over the burner due to slow heat transfer from the wall where ignition starts towards the centerline where un-combusted mixture exists. For smaller separation distances, reaction is more localized, with greater intensity, causing steeper temperature and composition gradients. When the separation distance is small, the transverse length scale of the fluid is small enough that the transverse heat transfer affects the centerline temperature, and thus, the maximum fluid temperature. In this case, the maximum fluid temperature is significantly lower than that for larger separations and incomplete conversion is observed. There appears to be an optimum plate separation that exhibits the shortest flame location. This distance permits the wall to preheat the inlet fluid fast enough, yet not to reduce significantly the centerline temperature. Burners with small plate-separation distances suffer from axial heat transfer through the walls of the burner, reducing the maximum fluid temperature and flame stability. Burners with large gaps slowly transport heat axially to preheat the feed, resulting in a late flame ignition and possible blowout.

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“…Due to the complexity of the coupling between chemical reaction, heat release and fluid dynamics, FWI has been investigated primarily based on three generic quenching configurations: head-on quenching (HOQ) with flame propagating to the wall at a normal angle (Hocks et al 1981;Westbrook et al 1981;Vosen et al 1985;Ezekoye et al 1992;Poinsot et al 1993;Ezekoye & Greif 1993;Wichman & Bruneaux 1995;Popp et al 1996;Bruneaux et al 1996;Popp & Baum 1997;Bruneaux et al 1997;Ezekoye 1998;Enomoto 2001;Foucher et al 2003;Bellenoue et al 2003;Boust et al 2007;Sotton et al 2007;Mann et al 2014;Lai & Chakraborty 2016a,b), side-wall quenching (SWQ) in which flame propagates parallel to the wall (Krmn & Milln 1953;Clendening et al 1981;Cheng et al 1981;Ng et al 1982;Saffman 1984;Lu et al 1991;Ezekoye et al 1992;Ezekoye & Greif 1993;Zhang et al 1996;Alshaalan & Rutland 1998;Andrae et al 2002;Enomoto 2002;Bellenoue et al 2003;Boust et al 2007;Tayebi et al 2008;Gruber et al 2010) and total quenching occurring in a tube with sufficiently small diameter (Putnam & Jensen 1948;Jarosiski 1983;Fairchild et al 1985;Jarosins...…”

Section: Introductionmentioning

confidence: 99%

Analysis of the flame–wall interaction in premixed turbulent combustion

2018

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The present work focuses on the flame–wall interaction (FWI) based on direct numerical simulations (DNS) of a head-on premixed flame quenching configuration at the statistically stationary state. The effects of FWI on the turbulent flame temperature, wall heat flux, flame dynamics and flow structures were investigated. In turbulent head-on quenching, particularly for high turbulence intensity, the distorted flames generally consist of the head-on flame part and the entrained flame part. The flame properties are jointly influenced by turbulence, heat generation from chemical reactions and heat loss to the cold wall boundary. For the present FWI configuration, as the wall is approached, the ‘influence zone’ can be identified as the region within which the flame temperature, scalar gradient and flame dilatation start to decrease, whereas the wall heat flux tends to increase. As the distance to the wall drops below the flame-quenching distance, approximately where the wall heat flux reaches its maximum value, chemical reactions become negligibly weak inside the ‘quenching zone’. A simplified counter-flow model is also proposed. With the reasonably proposed relation between the flame speed and the flame temperature, the model solutions match well with the DNS results, both qualitatively and quantitatively. Moreover, near-wall statistics of some important flame properties, including the flame dilatation, reaction progress variable gradient, tangential strain rate and curvature were analysed in detail under different wall boundary conditions.

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Raman spectroscopy measurements of flame quenching in a duct-type crevice

Cited by 8 publications

References 8 publications

Flame dynamics

Flame dynamics

WITHDRAWN: Scale effects on the combustion characteristics and flame stability of a methane-air mixture in continuous flow reactors

Analysis of the flame–wall interaction in premixed turbulent combustion

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