Flame quenching in front of a cold wall under two-step kinetics

Hocks, W.; Peters, Norbert; Adomeit, G.

doi:10.1016/0010-2180(81)90049-3

Cited by 56 publications

(13 citation statements)

References 7 publications

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“…Even though our calculations are different than those carried out before (Westbrook et al, 1981;Hocks et al, 1981;Sloane and Schoene, 1983), both calculations are in qualitative agreement concerning the fractions of CH, near the surface. The temperature changes slowly up to -0.5 mm and then drops sharply to room temperature.…”

Section: Combustion Near Surfacessupporting

confidence: 46%

“…Kee and coworkers have recently discussed possible practical applications of premixed CH,/air mixtures impinging on a flat surface (Kee et al, 1993). The role of cold surfaces on emission of unburned hydrocarbons from internal combustion engines has been considered some time ago for one-dimensional geometry when burned mixtures impinge on a surface (Westbrook et al, 1981;Hocks et al, 1981;Sloane and Schoene, 1983). However, the role of surfaces on ignition and extinction and the formation of undesired byproducts such as pollutants CO and CHzO or other intermediates which diffuse to or from the surface and affect homogeneous reactions are generally poorly understood.…”

Section: Introductionmentioning

confidence: 99%

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Products in methane combustion near surfaces

1994

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Section: Combustion Near Surfacessupporting

confidence: 46%

Section: Introductionmentioning

confidence: 99%

Products in methane combustion near surfaces

1994

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“…One-dimensional numerical simulations of laminar flame-wall interaction (FWI) configurations are reported in quenching studies by Hocks, Peters & Adomeit (1981), Westbrook, Adamczyk & Lavoie (1981), Ezekoye, Greif & Sawyer (1992), Popp, Smooke & Baum (1996), Egolfopoulos, Zhang & Zhang (1997), Popp & Baum (1997) and Dabireau et al (2003). While boundary layer flashback is a particular type of FWI process in which the flame propagates parallel to the solid surface, the focus of these FWI studies is mainly on premixed laminar flames propagating perpendicular to the wall and stagnating on it.…”

Section: Previous Workmentioning

confidence: 99%

Direct numerical simulation of premixed flame boundary layer flashback in turbulent channel flow

et al. 2012

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Direct numerical simulations are performed to investigate the transient upstream propagation (flashback) of premixed hydrogen–air flames in the boundary layer of a fully developed turbulent channel flow. Results show that the well-known near-wall velocity fluctuations pattern found in turbulent boundary layers triggers wrinkling of the initially flat flame sheet as it starts propagating against the main flow direction, and that the structure of the characteristic streaks of the turbulent boundary layer ultimately has an important impact on the resulting flame shape and on its propagation mechanism. It is observed that the leading edges of the upstream-propagating premixed flame are always located in the near-wall region of the channel and assume the shape of several smooth, curved bulges propagating upstream side by side in the spanwise direction and convex towards the reactant side of the flame. These leading-edge flame bulges are separated by thin regions of spiky flame cusps pointing towards the product side at the trailing edges of the flame. Analysis of the instantaneous velocity fields clearly reveals the existence, on the reactant side of the flame sheet, of backflow pockets that extend well above the wall-quenching distance. There is a strong correspondence between each of the backflow pockets and a leading edge convex flame bulge. Likewise, high-speed streaks of fast flowing fluid are found to be always colocated with the spiky flame cusps pointing towards the product side of the flame. It is suggested that the origin of the formation of the backflow pockets, along with the subsequent mutual feedback mechanism, is due to the interaction of the approaching streaky turbulent flow pattern with the Darrieus–Landau hydrodynamic instability and pressure fluctuations triggered by the flame sheet. Moreover, the presence of the backflow pockets, coupled with the associated hydrodynamic instability and pressure–flow field interaction, greatly facilitate flame propagation in turbulent boundary layers and ultimately results in high flashback velocities that increase proportionately with pressure.

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“…In engines, laminar models offer a good agreement for quench distances [21,20,32]. Because thermal wall effects first control the flame, many authors [11,27] used a simple chemistry. Other works [47,43] compare simple and complex chemistry.…”

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confidence: 99%

Flame/Wall Interactions: Laminar Study of Unburnt HC Formation

Chauvy

Delhom

Réveillon

et al. 2010

Flow Turbulence Combust

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This work presents a numerical study dedicated to the formation of unburnt hydrocarbon. Two configurations: head-on quenching (HOQ) on a planar wall and in crevices, are considered. It is well known that they contribute for an important part to the sources of hydrocarbon (HC) emission in a combustion chamber. The aim of this work is to use laminar flame simulations (LFS) to understand how the unburnt HC are produced near walls in gasoline engine. A skeletal mechanism (29 species and 48 reactions) mimicking iso-octane combustion is used. In the HOQ configuration, the flame front propagates toward the cold wall where quenching occurs. The numerical procedure and the chemical scheme used in this study are first validated by comparisons with literature results for the 1D case. Several aspects of flame wall quenching such as oxidation of unburnt HC, wall heat flux, quench distances as well as HC families are investigated by varying parameters like wall temperature and equivalence ratio. In a second part, crevices are considered to study the impact of wall imperfections in combustion chambers. Configurations with different geometrical and thermodynamic properties are tested. It leads to a wide range of flame properties and HC production modes. When incomplete combustion occurs, total HC (fuel + HC) concentration can reach very high levels at the wall. When the crevice is not wide enough, the flame cannot propagate and the quantity of HC is smaller than in the case where the flame can propagate (but the fuel is not oxidizing). If the crevice is wide enough for the flame to propagate, HOQ occurs at 1 the bottom of the crevice and HC accumulate in the corners. The computational results obtained in this work demonstrate the ability of LFS to reproduce incomplete combustion mechanisms that are responsible for a major part of HC production in gasoline engines.

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Flame quenching in front of a cold wall under two-step kinetics

Cited by 56 publications

References 7 publications

Products in methane combustion near surfaces

Products in methane combustion near surfaces

Direct numerical simulation of premixed flame boundary layer flashback in turbulent channel flow

Flame/Wall Interactions: Laminar Study of Unburnt HC Formation

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