Transition from pulled to pushed fronts in premixed turbulent combustion: Theoretical and numerical study

Sabelnikov, Vladimir; Lipatnikov, Andrei

doi:10.1016/j.combustflame.2015.03.016

Cited by 30 publications

(23 citation statements)

References 56 publications

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“…An alternative concept 54,55,69,80 of the Lewis number effects in premixed turbulent combustion emphasizes the propagation of highly stretched leading reaction zones into the unburned gas (the so-called leading edge concept). However, a comparison of the thermo-diffusive instability and leading point concepts is beyond the scope of the present study.…”

Section: Resultsmentioning

confidence: 99%

Effects of Lewis number on vorticity and enstrophy transport in turbulent premixed flames

2016

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The effects of Lewis number Le on both vorticity and enstrophy transport within the flame brush have been analysed using direct numerical simulation data of freely propagating statistically planar turbulent premixed flames, representing the thin reaction zone regime of premixed turbulent combustion. In the simulations, Le was ranged from 0.34 to 1.2 by keeping the laminar flame speed, thermal thickness, Damköhler, Karlovitz, and Reynolds numbers unchanged. The enstrophy has been shown to decay significantly from the unburned to the burned gas side of the flame brush in the Le ≈ 1.0 flames. However, a considerable amount of enstrophy generation within the flame brush has been observed for the Le = 0.34 case and a similar qualitative behaviour has been observed in a much smaller extent for the Le = 0.6 case. The vorticity components have been shown to exhibit anisotropic behaviour within the flame brush, and the extent of anisotropy increases with decreasing Le. The baroclinic torque term has been shown to be principally responsible for this anisotropic behaviour. The vortex stretching and viscous dissipation terms have been found to be the leading order contributors to the enstrophy transport for all cases, but the baroclinic torque and the sink term due to dilatation play increasingly important role for flames with decreasing Le. Furthermore, the correlation between the fluctuations of enstrophy and dilatation rate has been shown to play an important role in determining the material derivative of enstrophy based on the mean flow in the case of a low Le.

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Section: Resultsmentioning

confidence: 99%

Effects of Lewis number on vorticity and enstrophy transport in turbulent premixed flames

2016

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“…Reacting fronts that propagate through a moving fluid are important parts of many systems in science and engineering that are of intense current interest [1][2][3]. This includes geophysical problems such as the lock-exchange instability [4,5] of oceanic and atmospheric flows, the buoyancy and surface tension driven flows of chemical fronts [3,[6][7][8][9], the propagation of polymerization fronts [10], the rich spatiotemporal dynamics of forest fires [11,12], and the improved properties of combustion of pre-mixed gases in a turbulent fluid flow [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Propagating fronts in fluids with solutal feedback

Mukherjee

Paul

2020

Phys. Rev. E

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We numerically study the propagation of reacting fronts in a shallow and horizontal layer of fluid with solutal feedback and in the presence of a thermally driven flow field of counter-rotating convection rolls. We solve the Boussinesq equations along with a reaction-convection-diffusion equation for the concentration field where the products of the nonlinear autocatalytic reaction are less dense than the reactants. For small values of the solutal Rayleigh number the characteristic fluid velocity scales linearly, and the front velocity and mixing length scale quadratically, with increasing solutal Rayleigh number. For small solutal Rayleigh numbers the front geometry is described by a curve that is nearly antisymmetric about the horizontal midplane. For large values of the solutal Rayleigh number the characteristic fluid velocity, the front velocity, and the mixing length exhibit squareroot scaling and the front shape collapses onto an asymmetric self-similar curve. In the presence of counter-rotating convection rolls, the mixing length decreases while the front velocity increases. The complexity of the front geometry increases when both the solutal and convective contributions are significant and the dynamics can exhibit chemical oscillations in time for certain parameter values. Lastly, we discuss the spatiotemporal features of the complex fronts that form over a range of solutal and thermal driving.

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“…The symbols represent numerical values of v f (t) computed using Eq. (7). The solid line is a curve-fit through the data using Eq.…”

Section: A the Velocity Of A Propagating Frontmentioning

confidence: 99%

“…An improved fundamental understanding of propagating fronts in complex fluid flows would have a direct impact upon a number of important challenges that face us today. Examples include the combustion of pre-mixed gases in the turbulent flow that occurs in an internal combustion engine [3][4][5][6][7], the complex patterns of reagents that occur in many chemical industrial processes [1,2,[8][9][10], the spread of a forest fire [11][12][13], the spatiotemporal dynamics of a species invasion [14], and the outbreak of an epidemic such as the flu in a moving population [15,16].…”

Section: Introductionmentioning

confidence: 99%

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Velocity and geometry of propagating fronts in complex convective flow fields

Mukherjee

Paul

2019

Phys. Rev. E

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We numerically study the propagation of reacting fronts through three-dimensional flow fields composed of convection rolls that include time-independent cellular flow, spatiotemporally chaotic flow, and weakly turbulent flow. We quantify the asymptotic front velocity and determine its scaling with system parameters including the local angle of the convection rolls relative to the direction of front propagation. For cellular flow fields, the orientation of the convection rolls has a significant effect upon the front velocity and the front geometry remains relatively smooth. However, for chaotic and weakly turbulent flow fields the front velocity depends upon the geometric complexity of the wrinkled front interface and does not depend significantly upon the local orientation of the convection rolls. Using the box counting dimension we find that the front interface is fractal for chaotic and weakly turbulent flows with a dimension that increases with flow complexity.

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Transition from pulled to pushed fronts in premixed turbulent combustion: Theoretical and numerical study

Cited by 30 publications

References 56 publications

Effects of Lewis number on vorticity and enstrophy transport in turbulent premixed flames

Effects of Lewis number on vorticity and enstrophy transport in turbulent premixed flames

Propagating fronts in fluids with solutal feedback

Velocity and geometry of propagating fronts in complex convective flow fields

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