Effects of premixed flames on turbulence and turbulent scalar transport

Lipatnikov, Andrei; Chomiak, Jerzy

doi:10.1016/j.pecs.2009.07.001

Cited by 181 publications

(127 citation statements)

References 464 publications

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“…(40) in a recent review paper. 8 Nevertheless, this classical theoretical result, which is qualitatively consistent with the present DNS data, has yet been beyond the mainstream discussion of the influence of flame-generated turbulence on the burning rate.…”

supporting

confidence: 84%

“…Since that pioneering work, the thermal expansion effects were in the focus of research into turbulent combustion, 3-7 but progress in modeling them has yet been rather moderate, as reviewed elsewhere. 8,9 Nevertheless, the concept 1,2 of combustion acceleration due to flame-generated turbulence has never been disputed, to the best of the present authors' knowledge, at least in the case of weak or moderate turbulence 8 associated with a well-pronounced increase in the burning rate by the rms turbulent velocity u . The present letter aims at putting this widely accepted concept into question by showing that flamegenerated vorticity can smooth wrinkles of the local flame surface, thus, reducing its area and, consequently, decreasing turbulent burning velocity U t .…”

mentioning

confidence: 76%

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Letter: Does flame-generated vorticity increase turbulent burning velocity?

et al. 2018

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Direct numerical simulation data obtained from a statistically stationary, 1D, planar, weakly turbulent, premixed flame, which is associated with the flamelet combustion regime, are analyzed in order to show that generation of vorticity due to baroclinic torque within flamelets can impede wrinkling the reaction surface, reduce its area, and decrease the burning rate. These data call for revisiting the widely accepted concept of combustion acceleration due to flame-generated turbulence.

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supporting

confidence: 84%

mentioning

confidence: 76%

Letter: Does flame-generated vorticity increase turbulent burning velocity?

et al. 2018

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“…Flamegenerated pressure transport models remain unavailable [67]. However, a consistent form for the flamelet regime (f ) of combustion can be derived as shown in Appendix B,…”

Section: Pressure Transport In the Flamelet Regimementioning

confidence: 99%

The impact of dilatation, scrambling, and pressure transport in turbulent premixed flames

Tian

Lindstedt

2017

Combustion Theory and Modelling

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Premixed turbulent flames feature strong interactions between chemical reactions and turbulence that affect scalar and turbulence statistics. The focus of the present work is on clarifying the impact of pressure dilatation/flamelet scrambling effects with a comprehensive second-moment closure used for evaluation purposes. Model extensions that take into account flamelet orientation and molecular diffusion are derived. Isothermal pressure transport is included with an additional variable density contribution derived for the flamelet regime of combustion. The full closure is assessed by comparisons with direct numerical simulations (DNS) of statistically "steady" fully developed premixed turbulent planar flames at different expansion ratios. Subsequently, the prediction of lean premixed turbulent methane-air flames featuring fractal grid generated turbulence in an opposed jet geometry is considered. The overall agreement shows that "dilatation" effects contribute to counter-gradient transport and can also increase the turbulent kinetic energy significantly. Levels of anisotropy are broadly consistent with the DNS data and key aspects of opposed jet flames are well predicted. However, it is also shown that complications arise due to interactions between the imposed pressure gradient and combustion and that redistribution is affected along with the scalar flux at the leading edge. The latter is strongly affected by the reaction rate closure and, potentially, by pressure transport. Overall, the derived models offer significant improvements and can readily be applied to the modelling of premixed turbulent flames at practical rates of heat release.

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“…For instance, Figure 2 in a paper by Gouldin [6] indicates more than threefold decrease in the mean normal convective flux from the leading to the trailing edges of a V-shaped flame brush. Other experimental data that show the same effect were recently reviewed by Lipatnikov and Chomiak [7] (see Section 5.2 in the cited paper). It is also worth remembering that the difference in the speeds of planar and curved laminar flames scales as a ratio δ L /R f of the flame thickness to the radius of its curvature [8], and this ratio is much less than unity in a typical laminar premixed flame.…”

Section: Introductionmentioning

confidence: 58%

“…and (iii) balance equations for g u and the difference in w b and w u , derived by the present author [30] and discussed in detail elsewhere [7,31]. Here, 2 ) r=0 and g 1 are tuning parameters reported in Table 2.…”

Section: To Compute C[c(z)]mentioning

confidence: 97%

Burning Rate in Impinging Jet Flames

Lipatnikov

2011

Journal of Combustion

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A method for evaluating burning velocity in premixed turbulent flames stabilized in divergent mean flows is quantitatively validated using numerical approximations of measured axial profiles of the mean combustion progress variable, mean and conditioned axial velocities, and axial turbulent scalar flux, obtained by four research groups from seven different flames each stabilized in an impinging jet. The method is further substantiated by analyzing the combustion progress variable balance equation that is yielded by the extended Zimont model of premixed turbulent combustion. The consistency of the model with the aforementioned experimental data is also demonstrated.

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Effects of premixed flames on turbulence and turbulent scalar transport

Cited by 181 publications

References 464 publications

Letter: Does flame-generated vorticity increase turbulent burning velocity?

Letter: Does flame-generated vorticity increase turbulent burning velocity?

The impact of dilatation, scrambling, and pressure transport in turbulent premixed flames

Burning Rate in Impinging Jet Flames

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