Experimental study of flame stabilization in low Reynolds and Dean number flows in curved mesoscale ducts

Richecoeur, Franck; Kyritsis, Dimitrios C.

doi:10.1016/j.proci.2004.08.015

Cited by 129 publications

(58 citation statements)

References 19 publications

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“…These works showed that stoichiometric or near-stoichiometric mixtures give stable flames in the high and low incoming velocity regions and unstable flames in the middle velocity region, with flame extinctions and re-ignitions that are repeated periodically in time. A similar instability has been observed by Richecoeour and Kyritsis [11] and Evans and Kyritsis [12] for rich flames propagating in curved ducts and by Pizza et al [13] and Kurdyumov et al [14] for lean flames propagating in a bidimensional micro-channel.…”

Section: Introductionsupporting

confidence: 79%

Effect of the equivalence ratio, Damköhler number, Lewis number and heat release on the stability of laminar premixed flames in microchannels

Sánchez–Sanz

Fernández-Galisteo

Kurdyumov

2014

Combustion and Flame

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This is a postprint version of the following published document:Sánchez-Sanz, M. ; Fernández-Galisteo, D. ; Kurdyumov, V. N. Effect of the equivalence ratio, Damköhler number, Lewis number and heat release on the stability of laminar premixed flames in microchannels. Combustion and Flame, 2014, 161 (5) The effect of the equivalence ratio on the stability and dynamics of a premixed flame in a planar microchannel with a step-wise wall temperature profile is numerically investigated using the thermo-diffusive approximation. To characterize the stability behavior of the flame, we construct the stability maps delineating the regions with different flame dynamics in the inlet mass flow rate m vs. the equivalence ratio / parametric space. The flame stability is analyzed for fuels with different diffusivity by changing the Lewis numbers in the range 0:3 6 Le F 6 1:4. On the other hand, the Lewis number of the oxidizer is kept constant and equal to unity Le O ¼ 1. Our results show that, for very diffusive fuels, the stability of the flame varies significantly with the equivalence ratio, transitioning from stable flames for lean mixtures to highly unstable flames when / > 1. As the fuel Lewis number approaches unity, the stability behavior of the flame for lean and rich mixtures becomes more similar to give, in the equidiffusional case Le F ¼ 1, a symmetric stability map around the stoichiometric mixture / ¼ 1. In all cases considered, the most stable flames are always found around the stoichiometric mixtures / ¼ 1, when the flame instabilities are completely suppressed for very diffusive fuels Le F < 1, or are reduced to a narrow range of inflow velocities for fuel Lewis numbers equal or greater than unity.The ratio between the size of the channel and the flame thickness d turns out to be of great importance in the stability behavior of the flame. Keeping the rest of parameters constant, an increase in d for lean flames makes the flame considerably more unstable, confirming the findings of previous works. Nevertheless, as the stoichiometric ratio approaches / ¼ 1, that trend is reversed to give flames that become more stable as the size of the channel is increased.

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Section: Introductionsupporting

confidence: 79%

Effect of the equivalence ratio, Damköhler number, Lewis number and heat release on the stability of laminar premixed flames in microchannels

Sánchez–Sanz

Fernández-Galisteo

Kurdyumov

2014

Combustion and Flame

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“…For instance, stationary and repetitive ignition-extinction flames were stabilised in both a fixed-wall-temperature configuration and without an imposed wall-temperature distribution, in methane and/or hydrogen-air mixtures for medium and low flow rates, respectively; see [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

The differential diffusion effect of the intermediate species on the stability of premixed flames propagating in microchannels

Fernández-Galisteo

Jiménez

Sánchez–Sanz

et al. 2014

Combustion Theory and Modelling

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The propagation of premixed flames in adiabatic and non-catalytic planar microchannels subject to an assisted or opposed Poiseuille flow is considered. The diffusive-thermal model and the well-known two-step chain-branching kinetics are used in order to investigate the role of the differential diffusion of the intermediate species on the spatial and temporal flame stability. This numerical study successfully compares steady-state and time-dependent computations to the linear stability analysis of the problem. Results show that for fuel Lewis numbers less than unity, Le F < 1, and at sufficiently large values of the opposed Poiseuille flow rate, symmetry-breaking bifurcation arises. It is seen that small values of the radical Lewis number, Le Z , stabilise the flame to symmetric shape solutions, but result in earlier flashback. For very lean flames, the effect of the radical on the flame stabilisation becomes less important due to the small radical concentration typically found in the reaction zone. Cellular flame structures were also identified in this regime. For Le F > 1, flames propagating in adiabatic channels suffer from oscillatory instabilities. The Poiseuille flow stabilises the flame and the effect of Le Z is opposite to that found for Le F < 1. Small values of Le Z further destabilise the flame to oscillating or pulsating instabilities.

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“…Richecoeur and Kyritsis [14] investigated flame oscillations with sound emission in curved meso-scale ducts. Experiments in miniaturized liquid-film combustor by Sirignano et al [15] demonstrated externally and internally anchored flame modes.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigations of flame pattern formations in a radial microchannel

Fan

Minaev

Sereshchenko

et al. 2009

Proceedings of the Combustion Institute

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Experimental study of flame stabilization in low Reynolds and Dean number flows in curved mesoscale ducts

Cited by 129 publications

References 19 publications

Effect of the equivalence ratio, Damköhler number, Lewis number and heat release on the stability of laminar premixed flames in microchannels

Effect of the equivalence ratio, Damköhler number, Lewis number and heat release on the stability of laminar premixed flames in microchannels

The differential diffusion effect of the intermediate species on the stability of premixed flames propagating in microchannels

Experimental and numerical investigations of flame pattern formations in a radial microchannel

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