Consistent definitions of “Flame Displacement Speed” and “Markstein Length” for premixed flame propagation

Giannakopoulos, George; Gatzoulis, Athanasios; Frouzakis, Christos E.; Matalon, Moshe; Tomboulides, Ananias

doi:10.1016/j.combustflame.2014.10.015

Cited by 118 publications

(86 citation statements)

References 43 publications

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“…This marks a clear advantage over DNS, where one is faced with the difficulty of selecting an appropriate iso-surface of temperature or concentration to represent the flame surface. A poor choice of the isosurface could lead to uncertainties in the flame displacement speed [41], and different contours could lead to significantly different values of turbulent flame speed [35]. Another advantage of our methodology is the ability, through a closed-loop flow control system, to regulate the mean flame position and the turbulent intensity immediately ahead of the flame.…”

Section: Introductionmentioning

confidence: 99%

Effect of folds and pockets on the topology and propagation of premixed turbulent flames

Fogla

Creta

Matalon

2015

Combustion and Flame

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Section: Introductionmentioning

confidence: 99%

Effect of folds and pockets on the topology and propagation of premixed turbulent flames

Fogla

Creta

Matalon

2015

Combustion and Flame

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“…Therefore,i ti si rrelevant which flame surface is detected exactly in the experiment for evaluation of the flame speed with Equation (3). Thes ame conclusion wasd rawn by Giannakopoulos [18] through detailed numerical simulations of propane/air flames and by Groot and de Goey, [19] who applied flamelet simulations for spherically expanding flames.…”

Section: Resultsmentioning

confidence: 99%

“…Giannakopoulos et al [18] reported as ignificant impact of the flame front definition regarding the displacements peed by direct numerical calculationso fp ropane/air spherically expandingf lames.T he sensitivity of flame displacement speed to stretchw as found to vary with the definition of the flame surface assuming zero flame thickness.G root and de Goey [19] calculated spherically expanding methane/air flames by means of af lamelet approacha nd confirmed that an unsteady changei nt hickness of the flame front only had am inore ffect on flame speed. To include the influence of af inite flame thickness,a nalytical correction methods have been proposed to correct the flame speeds obtainedf rom zero-thicknessa ssumptions.…”

Section: Introductionmentioning

confidence: 99%

Impact of Infinite Thin Flame Approach on the Evaluation of Flame Speed using Spherically Expanding Flames

et al. 2017

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Combustion is an important part of most current and future overall energy‐conversion systems, especially if using renewable fuels in energy‐storage concepts. Therefore, the laminar flame speed, which is a key parameter for the design of combustion systems, needs to be known for a growing multitude of different thermodynamic conditions and fuels. The spherically expanding flame method is one of the few techniques that enables the flame speed to be measured under particular conditions such as elevated pressure and temperature as well as under turbulent conditions, which are important for energy‐conversion applications. The radius of a spherically propagating flame is tracked and used for evaluation of the flame speed. Usually, the flame is assumed to be infinitely thin. To assess the influence of this assumption, direct numerical simulations were conducted for the experimental setup and compared with measurements and correlations from the literature. The flame speed determined by the consumption rate of fuel, which takes a finite thickness of the flame into account, was found to be always larger than the flame speed computed by assuming an infinitely thin flame. The difference between these flame speeds was observed to be as large as approximately 10–20 % in the evaluation range of the measured flame radii, which decreases with growing flame radius. This gives rise to the discrepancies in the flame speeds obtained from different measurement methods. An analytical estimation for this difference was developed as a function of the flame radius, which showed quantitatively good agreement with the simulation results and may be used for experimental validations of the flame speed. Both premixed H2/air and CH4/air flames with equivalence ratios ranging from lean to rich conditions were studied.

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“…To assess the preferential diffusion on flame acceleration under high turbulence and elevated pressure, we next compute the response of preferential diffusion on the local flame displacement speed (i.e., flame front speed relative to the flow) [50,51] at Ret=150, and at p=4bar. We investigate how the local flame displacement speed varies with flame stretch between the flame with non-unity Lewis number and the flame with unity-Lewis number at Ret=150, and at p=4bar.…”

Section: Flame Speedmentioning

confidence: 99%

“…We calculate the flame displacement speed for expanding spherical flames with and without preferential diffusion at Ret=150, and at p=4bar and plot against the local stretch rate on the iso-surface in the preheat zone, reaction zone and fully burned zone. The flame displacement speed, which measures the difference between the flame front speed and the flow speed, is computed using the following expression [50,51]: (27) where all the terms are evaluated along the selected isotherms. In Eq.…”

Section: Flame Speedmentioning

confidence: 99%

High hydrogen content syngas fuel burning in lean premixed spherical flames at elevated pressures: Effects of preferential diffusion

Dinesh

Shalaby

Luo

et al. 2016

International Journal of Hydrogen Energy

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This study addresses the effects of preferential diffusion on flame structure and propagation of high hydrogen content (HHC) turbulent lean premixed hydrogen-carbon monoxide syngas flames at elevated pressures. The direct numerical simulations with detailed chemistry were performed in three-dimensional domain for expanding spherical flame configuration in a constant pressure combustion chamber. To identify the role of preferential diffusion on flame structure and propagation under low and high turbulence levels at elevated pressure, simulations were performed at an initial turbulent Reynolds number of 15 and 150 at a pressure value of 4bar. The results demonstrate that the thermo-diffusive instability greatly influences the lean premixed syngas cellular flame structure due to strong preferential diffusion effects under low turbulence level at elevated pressure. In contrast, the results reveal that the thermo-diffusive effects are destabilising and preferential diffusion is overwhelmed by turbulent mixing under high turbulence level at elevated pressure. This finding suggests that the development of cellular flame structure is dominated by turbulence with little or no contribution from the thermo-diffusive instability for the lean premixed syngas flame which operates under conditions of high turbulence and elevated pressures. However, results demonstrate that the flame acceleration and species diffusive flux are still influenced by the preferential diffusion for the lean premixed syngas flame which operates under conditions of high turbulence and elevated pressures.

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Consistent definitions of “Flame Displacement Speed” and “Markstein Length” for premixed flame propagation

Cited by 118 publications

References 43 publications

Effect of folds and pockets on the topology and propagation of premixed turbulent flames

Effect of folds and pockets on the topology and propagation of premixed turbulent flames

Impact of Infinite Thin Flame Approach on the Evaluation of Flame Speed using Spherically Expanding Flames

High hydrogen content syngas fuel burning in lean premixed spherical flames at elevated pressures: Effects of preferential diffusion

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