Investigation of pressure effects on the small scale wrinkling of turbulent premixed Bunsen flames

Fragner, Romain; Halter, Fabien; Mazellier, Nicolas; Chauveau, Christian; Gökalp, İskender

doi:10.1016/j.proci.2014.06.036

Cited by 35 publications

(13 citation statements)

References 35 publications

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“…4 (b) is normalized with the thermal flame thickness which scales as δ th~p −0.5 . This shows that the PDF distributions broaden with increasing pressure with higher probabilities of larger curvatures, indicating the enhancement of smaller scale flame front wrinkling which is consistent with the observations in Lachaux et al [30] and Fragner et al [31].…”

Section: Resultssupporting

confidence: 90%

Flame Curvature Distribution in High Pressure Turbulent Bunsen Premixed Flames

Klein

Nachtigal

Hansinger

et al. 2018

Flow Turbulence Combust

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The flame curvature statistics of turbulent premixed Bunsen flames have been analysed in this paper using a Direct Numerical Simulation (DNS) database of turbulent Bunsen flames at ambient and elevated pressures. In order to be able to perform a large parametric study in terms of pressure, heat release parameter, turbulence conditions and nozzle diameter, a single step Arrhenius type irreversible chemistry has been used for the purpose of computational economy, where thermo-chemical parameters are adjusted to match the behavior of stoichiometric methane-air flames. This analysis focuses on the characterization of the local flame geometry in response to turbulence and hydro-dynamic instability. The shape of the flame front is found to be consistent with existing experimental data. Although the Darrieus Landau instability promotes cusp formation, a qualitatively similar flame morphology can be observed for hydrodynamically stable flames. A criterion has been suggested for the curvature PDF to become negatively skewed.

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Section: Resultssupporting

confidence: 90%

Flame Curvature Distribution in High Pressure Turbulent Bunsen Premixed Flames

Klein

Nachtigal

Hansinger

et al. 2018

Flow Turbulence Combust

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“…[52] was recently upgraded by Refs. [53,54] by replacing the mono-grid turbulence generator by a multi-scale grids generator [55] with the aim of achieving a higher turbulent intensity. The Bunsen burner (see Fig.…”

Section: A Experimental Setup and Description Of The Databasementioning

confidence: 99%

Geometrical properties of turbulent premixed flames and other corrugated interfaces

et al. 2016

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This study focuses on the geometrical properties of turbulent flame fronts and other interfaces. Toward that end, we use an original tool based on proper orthogonal decomposition (POD), which is applied to the interface spatial coordinates. The focus is mainly on the degree of roughness of the flame front, which is quantified through the scale dependence of its coverage arclength. POD is first validated by comparing with the caliper technique. Fractal characteristics are extracted in an unambiguous fashion using a parametric expression which appears to be impressively well suited for representing Richardson plots. Then it is shown that, for the range of Reynolds numbers investigated here, the scale-by-scale contribution to the arclength does not comply with scale similarity, irrespectively of the type of similarity which is invoked. The finite ratios between large and small scales, referred to as finite Reynolds number effects, are likely to explain this observation. In this context, the Reynolds number that ought to be achieved for a proper inertial range to be discernible, and for scale similarity to be likely to apply, is calculated. Fractal characteristics of flame folding are compared to available predictions. It is confirmed that the inner cutoff satisfactorily correlates with the Kolmogorov scale while the outer cutoff appears to be proportional to the integral length scale. However, the scaling for the fractal dimension is much less obvious. It is argued that much higher Reynolds numbers have to be reached for drawing firm statements about the evolution (or constancy) of the fractal dimension with respect to flame and flow parameters. Finally, a heuristic phenomenology of corrugated interfaces is highlighted. The degree of generality of the latter phenomenology is confirmed by comparing the folding of different interfaces including a turbulent-nonturbulent interface, a liquid jet destabilized by a surrounding air jet, a cavitating flow, and an isoscalar evolving in a turbulent medium. The latter outcome is likely to have strong implications for modeling the corrugation of turbulent interfaces occurring in many physical situations.

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“…Increased pressure affects both, flame and turbulence characteristics alongside chemical kinetics. As an example, for hydrocarbon fuels, laminar burning velocities and flame thicknesses typically decrease with a pressure rise (Fragner et al 2015). This in turn affects kinematic viscosity, the Reynolds, Damköhler and Karlovitz numbers, reaction rates and flame speed, extinction, ignition delay time and pollutant formation (Bougrine et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Algebraic Flame Surface Density Modelling of High Pressure Turbulent Premixed Bunsen Flames

Rasool

Chakraborty

Klein

2020

Flow Turbulence Combust

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Performance of representative algebraic flame surface density (FSD) models have been a-priori assessed based on a direct numerical simulation database consisting of four turbulent premixed Bunsen flames at four different pressure levels. Results indicate that for a given resolution of the flame front, the considered algebraic FSD closures perform in a qualitatively similar manner irrespective of pressure variation. However, for a given computational mesh, the performance deteriorates as flame thickness decreases with increasing pressure. Additionally, the contribution of the subgrid scale surface-filtered density-weighted tangential diffusion component of the displacement speed tends to increase with pressure increment, further complicating the modelling of FSD. Further analysis also indicate that the inner cut-off scale normalized by the thermal flame thickness increases with increasing pressure, possibly due to the presence of Darrieus–Landau instability which is more likely to occur at higher pressure due to a larger ratio of hydrodynamic length scale to thermal flame thickness.

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Investigation of pressure effects on the small scale wrinkling of turbulent premixed Bunsen flames

Cited by 35 publications

References 35 publications

Flame Curvature Distribution in High Pressure Turbulent Bunsen Premixed Flames

Flame Curvature Distribution in High Pressure Turbulent Bunsen Premixed Flames

Geometrical properties of turbulent premixed flames and other corrugated interfaces

Algebraic Flame Surface Density Modelling of High Pressure Turbulent Premixed Bunsen Flames

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