Turbulent transport in premixed flames approaching extinction

Goh, Kok Hin Henry; Geipel, Philipp; Lindstedt, R.P.

doi:10.1016/j.proci.2014.06.030

Cited by 16 publications

(9 citation statements)

References 28 publications

(2 reference statements)

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“…16 (top and middle row). Similar trends were observed by Goh et al [8,33] at lower turbulence levels. The data show that the combustion mode transition is sufficiently strong to directly impact the flow field.…”

Section: Unconditional Velocity Statisticssupporting

confidence: 89%

“…1), originally developed by Geyer et al [11], was extensively used by Geipel et al [10] and Goh et al [8,31,32,33] and is identical to the the configuration used by Hampp et al [22,23]. A cross fractal grid (CFG; [34]) was installed 50 mm upstream the UN exit, featuring a BR of 65 % with maximum and minimum bar widths of 2.0 mm and 0.50 mm.…”

Section: Methods Assumptions and Proceduresmentioning

confidence: 99%

See 1 more Smart Citation

Distributed Low Temperature Combustion: Fundamental Understanding of Combustion Regime Transitions

Lindstedt¹,

Hampp²,

Kraus³

et al. 2016

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Section: Unconditional Velocity Statisticssupporting

confidence: 89%

Section: Methods Assumptions and Proceduresmentioning

confidence: 99%

Distributed Low Temperature Combustion: Fundamental Understanding of Combustion Regime Transitions

Lindstedt¹,

Hampp²,

Kraus³

et al. 2016

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“…The opposed jet configuration, shown in Fig. 1, was originally developed by Geyer et al [32] and Geipel et al [30] and is a direct advancement of the burner used by Goh and co-workers [11,12]. Flames in opposed jet geometries can suffer from low frequency instabilities as mentioned by Geipel et al [30] and Coppola and Gomez [47].…”

Section: Burner Configurationmentioning

confidence: 99%

“…via flameless combustion modes [10]. Related combustion regime transitions in lean (Φ = 0.0, 0.2, 0.4, 0.6 and 0.8) premixed JP-10 (exotetrahydrodicyclopentadiene) flames have been studied by Goh et al [11] using a back-to-burnt (BTB) opposed jet configuration and comparisons made with the approach to extinction of conventional flames in the corresponding twin flame geometry [12]. Relevant conditions can also be achieved in vitiated jet flames and reaction zone broadening within a shear layer of premixed CH 4 /air flames at varying stoichiom-etry and jet velocity was investigated by Duwig et al [13].…”

Section: Introductionmentioning

confidence: 99%

Quantification of combustion regime transitions in premixed turbulent DME flames

Hampp

Lindstedt

2017

Combustion and Flame

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The current study quantifies the probability of encountering up to five fluid states (reactants, combustion products, mixing fluid, fluids with low and high reactivity) in premixed turbulent DME flames as a function of the Damköhler number. The flames were aerodynamically stabilised in a back-to-burnt opposed jet configuration featuring fractal grid generated multi-scale turbulence (Re≃ 18,400 and Ret > 370). The chemical timescale was varied via the mixture stoichiometry resulting in a wide range of Damköhler numbers (0.08 ≤ Da ≤ 5.6). The mean turbulent strain (≥ 3200 s−1) exceeded the extinction strain rate of the corresponding laminar flames for all mixtures. Simultaneous Mie scattering, OH-PLIF and PIV were used to identify the fluid states and supporting computations show that the thermochemical state (e.g. OH and CH concentrations) at the twin flame extinction point correlates well with flames in the back-to-burnt geometry at the corresponding rate of heat release. For mixtures where the bulk strain (≃ 750 s−1) was similar to (or less than) the extinction strain rate, fluids with low and high reactivity could accordingly be segregated by a threshold based on the OH concentration at the extinction point. A sensitivity analysis of the distribution between the fluid states was performed. The flow conditions were further analysed in terms of Damköhler and Karlovitz numbers. The study provides (i) the evolution of multi-fluid probability statistics as a function of the Damköhler number, including (ii) the flow direction across fluid interfaces and OH gradients, (iii) mean flow field statistics, (iv) conditional velocity statistics and (v) a tentative combustion regime classification

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“…78 had proposed a highly turbulent counterflow flame as a useful benchmark of complexity intermediate between laminar flames and practical systems. Recent work by Lindstedt’s group 77,79–81 concerns a turbulent opposed jet burner generating turbulence using multi-scale fractal grids instead of the conventional perforated plates, which facilitates higher turbulence intensities at much lower bulk velocities. The perforated plate turbulence generator used by Copolla et al.…”

Section: Counterflow Diffusion/partially Premixed Flames Applicationsmentioning

confidence: 99%

Advances in understanding combustion phenomena using non-premixed and partially premixed counterflow flames: A review

Ravikrishna

Sahu

2017

International Journal of Spray and Combustion Dynamics

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Counterflow flames provide an ideal platform for understanding the flame structure and as a model to study the effect of physical and chemical perturbations on the flame structure. This article reviews the advances made in the understanding of combustion dynamics and chemistry through experimental and numerical studies in counterflow non-premixed and partially premixed flames. Key contributions on fundamental aspects such as extinction, ignition and effect of perturbations on the stability of diffusion flames are first summarized and analysed. The review then focuses on the progress made in the understanding of the effect of inert particles and flame suppressants on the flame characteristics. A review of detailed studies on edge flames facilitates further understanding of local quenching and re-ignition phenomena in highly turbulent flames. The influence of radiation model and unsteady flow-conditions on the flame kinetics and dynamics along with work on NO x kinetics has been discussed. The review also outlines that specific experiments need to be carried out over a wide range of conditions for further understanding and validation of numerical models.

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Turbulent transport in premixed flames approaching extinction

Cited by 16 publications

References 28 publications

Distributed Low Temperature Combustion: Fundamental Understanding of Combustion Regime Transitions

Distributed Low Temperature Combustion: Fundamental Understanding of Combustion Regime Transitions

Quantification of combustion regime transitions in premixed turbulent DME flames

Advances in understanding combustion phenomena using non-premixed and partially premixed counterflow flames: A review

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