The development of wrinkled turbulent premixed flames

Thomas, A.

doi:10.1016/0010-2180(86)90043-x

Cited by 26 publications

(7 citation statements)

References 12 publications

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“…The variation of the combustion rate observed when the flame becomes turbulent is directly linked to the increase of the flame surface. As suggested by Thomas [Thomas, 1986] can results simultaneously from the mean flame size evolution and the flame wrinkling produced by the flow-field. This last contribution can be characterized by a wrinkling factor, W, defined as the ratio of the total flame surface area, A, to the area, A' of the smooth sphere of radius R [Thomas, 1986]:…”

Section: Geometrical Characteristicsmentioning

confidence: 97%

An Experimental Study of Freely Propagating Premixed Flames at Various Lewis Numbers

Renou

Boukhalfa

2001

Combustion Science and Technology

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Several freely-propagating premixed turbulent flames are experimentally obtained in a decaying isotropic turbulent flow for various Lewis numbers. The high speed laser sheet tomography technique is applied to visualize the temporal evolution of the spatial properties of the flame fronts and to study the influence of the Lewis number (Le) on the flame front structures at fixed u' /S~. This experimental study is also performed to highlight the transient effect over time of the flame front geometry of turbulent premixed flames under varying turbulence conditions and fuel/air mixtures.From the tomographic recordings, the flame surface properties and mean radii are calculated at each stage of flame development and allow the mean global stretch and the mean burning velocity at each step of the flame propagation to be determined. As expected from asymptotic theory, the effects of preferential-diffusion/stretch interactions for low turbulent conditions can be modeled according to a linear correlation. For Le-l, the mean burning velocity decreases slightly with the mean flame stretch. and the Markstein lengths are independent of the turbulent conditions. For Le-I.6 and Le-O.3, the mean burning velocity evolution with mean stretch shows an opposite trend both for laminar and turbulent flames. The linear dependence between and predicted for weak stretch in laminar flames appears to be valid for turbulent premixed flames, except for highly turbulent hydrogen/air flames u' /S~= 1.89. For small values of Lewis numbers nnd/or high values of u' /S~l the weakly stretched approach associated with the asymptotic theory is insufficient for modeling premixed turbulent combustion.

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Section: Geometrical Characteristicsmentioning

confidence: 97%

An Experimental Study of Freely Propagating Premixed Flames at Various Lewis Numbers

Renou

Boukhalfa

2001

Combustion Science and Technology

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“…As indicated by Pischinger and Heywood (1990), few multi-dimensional models simulating spark-generated flame ignition are available today. Models based on stochastic approaches (Pope and Cheng, 1986) or on flame wrinkling predictions (Thomas, 1986;Mantel and Borghi, 1994;Boudieret al, 1992;Herwegand Maly, 1992) have been proposed but fundamental information to test these models is lacking in most cases.…”

Section: Introductionmentioning

confidence: 99%

Effects of Mean Flow on Premixed Flame Ignition

Baum

Poinsot

1995

Combustion Science and Technology

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Ignition isan important processin many practicaldevices. Most studiesofignition have been performed in stagnant flows only, using asymptotic methods, numerical techniques or experiments. Although the importance of the minimum energy and ignition delay times was shown by these studies, the effects of turbulence on these processes remain unknown. In this paper Direct Numerical Simulation (DNS) is used to provide precise data on one of the mechanisms controlling ignition, i.e., the effect of a large flow velocity at the point where the spark is produced. Spark ignition in a constant speed flow is simulated using a thermal model for the spark. Results show that a minimal power is necessary for successful ignition in nonzero mean flows. This minimal power depends nearly linearly on the flow speed (except for very low speeds). For very high heating powers the ignition delay times become independent from the flow speed. A characteristic flame radius may be used to describe the ignition limit. For zero mean flows this radius is close to the one resulting from asymptotic analysis. It increases with increasing flow speed but seems ro be independent from spark duration. Finally a model based on a simplified one-dimensional configuration is developed to predict ignition in a nonzero mean flow. It is shown that this model may be used over a large range of parameters to replace DNS resulrs.

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“…6, as the turbulence increases, the amplitude and the spatial frequency of the flame wrinkles strongly increase. As the flame size becomes greater than that of the largest turbulence structure represented by the integral length scale, flame wrinkling starts to appear due to the mutual interaction between the propagating of flame front and local flow field close to it [27,28]. Noticeably, as depicted in Fig.6, for all the tested cases, after a certain time of development, the propagating flame front reaches one geometry shape and keeps it with temporal evolution.…”

Section: Flame Growth and Morphology Characterisesmentioning

confidence: 83%

Turbulent burning characteristics of FACE-C gasoline and TPRF blend associated with the same RON at elevated pressures

Mannaa

Bréquigny

Mounaïm‐Rousselle

et al. 2018

Experimental Thermal and Fluid Science

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FACE-C gasoline/air and TPRF (51.6 vol. % iso-octane, 21.5 vol.% n-heptane and 26.9 vol.% toluene)/air mixtures corresponding to the same RON of 85 were characterized in terms of determining their burning rates in a fan stirred turbulent vessel and filmed using high speed dual Schlieren imaging. Moreover, Mie scattering planar laser tomography was employed to characterize the variations of flame morphology induced by the coincident existence of different turbulent length scales and the susceptibility to develop cellular structures at elevated pressures (through the Darieus-Landau instability). Measurements were performed in a well-controlled environment of initial pressures 0.1, 0.5 and 1.0 MPa at a fixed initial temperature of 358 k. These measurements were conducted at a range of measured turbulence intensities from 0.5 to 2.0 m/s. The enhancement of turbulent flame speed S T as a function of turbulent intensity was sized. The absence of bending regime was accounted for based on the size of the vessel and limited range of turbulent intensities investigated in the present work.

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The development of wrinkled turbulent premixed flames

Cited by 26 publications

References 12 publications

An Experimental Study of Freely Propagating Premixed Flames at Various Lewis Numbers

An Experimental Study of Freely Propagating Premixed Flames at Various Lewis Numbers

Effects of Mean Flow on Premixed Flame Ignition

Turbulent burning characteristics of FACE-C gasoline and TPRF blend associated with the same RON at elevated pressures

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