The turbulent flame speed for low-to-moderate turbulence intensities: Hydrodynamic theory vs. experiments

Fogla, Navin; Creta, Francesco; Matalon, Moshe

doi:10.1016/j.combustflame.2016.06.023

Cited by 60 publications

(45 citation statements)

References 47 publications

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“…The point is that the vast majority of models of the influence of turbulence on premixed combustion (i) deal with single-step chemistry and (ii) neglect density variations, with a few exceptions [13][14][15][16]. Accordingly, to explore foundations of such models, heavy DNS with complex chemistry are not necessary, but extension of the range of studied conditions appears to be of paramount importance.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulation study of statistically stationary propagation of a reaction wave in homogeneous turbulence

Lipatnikov

2017

Phys. Rev. E

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A three-dimensional (3D) direct numerical simulation (DNS) study of the propagation of a reaction wave in forced, constant-density, statistically stationary, homogeneous, isotropic turbulence is performed by solving Navier-Stokes and reaction-diffusion equations at various (from 0.5 to 10) ratios of the rms turbulent velocity U to the laminar wave speed, various (from 2.1 to 12.5) ratios of an integral length scale of the turbulence to the laminar wave thickness, and two Zeldovich numbers Ze = 6.0 and 17.1. Accordingly, the Damköhler and Karlovitz numbers are varied from 0.2 to 25.1 and from 0.4 to 36.2, respectively. Contrary to an earlier DNS study of self-propagation of an infinitely thin front in statistically the same turbulence, the bending of dependencies of the mean wave speed on U is simulated in the case of a nonzero thickness of the local reaction wave. The bending effect is argued to be controlled by inefficiency of the smallest scale turbulent eddies in wrinkling the reaction-zone surface, because such small-scale wrinkles are rapidly smoothed out by molecular transport within the local reaction wave.

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Section: Introductionmentioning

confidence: 99%

Direct numerical simulation study of statistically stationary propagation of a reaction wave in homogeneous turbulence

Lipatnikov

2017

Phys. Rev. E

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“…Hydrodynamic flame instabilities can be important for turbulent burning, particularly at high pressure [1] . Even without turbulence, the propagation of a laminar flame in a tube can lead to 5 a very complex non-linear evolution (these flames are often called self-turbulent) if the tube is large enough [2].…”

Section: Introductionmentioning

confidence: 99%

Darrieus–Landau instability and Markstein numbers of premixed flames in a Hele-Shaw cell

Sarraf

Almarcha

Quinard

et al. 2019

Proceedings of the Combustion Institute

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Hydrodynamic flame instabilities are studied in a Hele-Shaw burner. By studying the development of perturbations, starting from a 2D Bunsen flame at the top of the burner, growth rates are measured for propane and methane-air mixtures, and compared to theoretical predictions. It is found that the dispersion relation in a Hele-Shaw cell has the same dependence with wavenumber σ = k − k 2 as the one predicted in tubes. Markstein numbers relative to fresh gases are obtained for propane and methane flames and compared to the literature.

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“…However, Figs. 3, 4, 5 and 6 neither challenge concept (ii) nor contradict to DNS studies [45–47, 70] that indicated substantial influence of the DL mechanism on premixed turbulent combustion.…”

Section: Discussionmentioning

confidence: 73%

“…Indeed, first, a recent 2D DNS investigation [47] of weakly turbulent premixed flames subject to the DL instability also shows that the density ratio weakly affects turbulent flame speed, e.g. an increase in σ by a factor of three (from two to six) results in increasing by 10 % only, see Fig.…”

Section: Discussionmentioning

confidence: 96%

“…1 from [45] does not indicate a substantial effect of σ on the mean (time-averaged) in the flamelet regime of premixed turbulent combustion. Recent unsteady 2D simulations of hydrodynamically unstable (“supercritical”) flames [46, 47] indicate a weak dependence of S t on σ in spite of substantial influence of the DL instability on the simulated flames. …”

Section: Introductionmentioning

confidence: 99%

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Does Density Ratio Significantly Affect Turbulent Flame Speed?

Lipatnikov

Jiang

et al. 2017

Flow Turbulence Combust

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In order to experimentally study whether or not the density ratio σ substantially affects flame displacement speed at low and moderate turbulent intensities, two stoichiometric methane/oxygen/nitrogen mixtures characterized by the same laminar flame speed S L = 0.36 m/s, but substantially different σ were designed using (i) preheating from T u = 298 to 423 K in order to increase S L, but to decrease σ, and (ii) dilution with nitrogen in order to further decrease σ and to reduce S L back to the initial value. As a result, the density ratio was reduced from 7.52 to 4.95. In both reference and preheated/diluted cases, direct images of statistically spherical laminar and turbulent flames that expanded after spark ignition in the center of a large 3D cruciform burner were recorded and processed in order to evaluate the mean flame radius and flame displacement speed with respect to unburned gas. The use of two counter-rotating fans and perforated plates for near-isotropic turbulence generation allowed us to vary the rms turbulent velocity by changing the fan frequency. In this study, was varied from 0.14 to 1.39 m/s. For each set of initial conditions (two different mixture compositions, two different temperatures T u, and six different , five (respectively, three) statistically equivalent runs were performed in turbulent (respectively, laminar) environment. The obtained experimental data do not show any significant effect of the density ratio on S t. Moreover, the flame displacement speeds measured at u′/S L = 0.4 are close to the laminar flame speeds in all investigated cases. These results imply, in particular, a minor effect of the density ratio on flame displacement speed in spark ignition engines and support simulations of the engine combustion using models that (i) do not allow for effects of the density ratio on S t and (ii) have been validated against experimental data obtained under the room conditions, i.e. at higher σ.

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The turbulent flame speed for low-to-moderate turbulence intensities: Hydrodynamic theory vs. experiments

Cited by 60 publications

References 47 publications

Direct numerical simulation study of statistically stationary propagation of a reaction wave in homogeneous turbulence

Direct numerical simulation study of statistically stationary propagation of a reaction wave in homogeneous turbulence

Darrieus–Landau instability and Markstein numbers of premixed flames in a Hele-Shaw cell

Does Density Ratio Significantly Affect Turbulent Flame Speed?

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