Responses of a Lifted Non-Premixed Flame to Acoustic Forcing. Part 2

Baillot, Françoise; Demare, David

doi:10.1080/00102200600713252

Cited by 12 publications

(4 citation statements)

References 20 publications

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“…One of the models describing lifted flame stabilisation assumes that the leading edge of the flame is on average situated where the local axial velocity is equal to the turbulent propagation speed of the flame and the mean equivalence ratio is close to the stoichiometric value [21,37]. Several papers [11] have also reported an important role for large-scale vortices in the lifted flame stabilisation that has been confirmed by the lifted flame response when the development of the vortices is externally forced [5].…”

Section: Introductionmentioning

confidence: 89%

Flow Structure of Swirling Turbulent Propane Flames

Алексеенко

Дулин

Kozorezov

et al. 2011

Flow Turbulence Combust

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Flow structure of premixed propane-air swirling jet flames at various combustion regimes was studied experimentally by stereo PIV, CH* chemiluminescence imaging, and pressure probe. For the non-swirling conditions, a nonlinear feedback mechanism of the flame front interaction with ring-like vortices, developing in the jet shear layer, was found to play important role in the stabilisation of the premixed lifted flame. For the studied swirl rates (S = 0.41, 0.7, and 1.0) the determined domain of stable combustion can be divided into three main groups of flame types: attached flames, quasi-tubular flames, and lifted flames. These regimes were studied in details for the case of S = 1.0, and the difference in the flow structure of the vortex breakdown is described. For the quasi-tubular flames an increase of flow precessing above the recirculation zone was observed when increased the stoichiometric coefficient from 0.7 to 1.4. This precessing motion was supposed to be responsible for the observed increase of acoustic noise generation and could drive the transition from the quasi-tubular to the lifted flame regime.

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Section: Introductionmentioning

confidence: 89%

Flow Structure of Swirling Turbulent Propane Flames

Алексеенко

Дулин

Kozorezov

et al. 2011

Flow Turbulence Combust

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“…Considering this, the methane combustion stabilization methods, based on new physical principles, are being actively developed in recent times. Such methods include an acoustic [30][31][32][33][34] and electrical effects on flames [35][36][37][38][39]. Definitely, these methods of intensification are promising, however, they require detailed research and testing.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Methane Combustion Efficiency in a High-Enthalpy Oxygen-Containing Flow

2022

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The article presents the experimental study analysis results of the methane combustion efficiency in a high-enthalpy oxygen-containing flow (HOF) inside of constant cross-section channel, finite along the length. The range of initial HOF enthalpies was considered from 350 to 700 kJ/kg. The regularities of the HOF initial enthalpy influence on the methane combustion efficiency were obtained. The values of the fuel excess coefficient under which the maximum coefficients of methane combustion completeness in the HOF are realized were determined. The data obtained indicate the realization of transitional diffusion-kinetic modes of methane combustion and make it possible to assess the factors limiting the combustion process.

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“…Abdurakipov et al 15 demonstrated that in comparison to natural flames the excitation ensures stable combustion regimes and visibly shifts the blow-off limits. A research on an excited lifted non-premixed flame in a hysteresis regime, i.e., when depending on initial conditions a flame can be attached to a nozzle or remain lifted for the same fuel velocity, was performed by Demare and Baillot 16,17 . It was shown that, by changing the amplitude and frequency of excitation one can enhance the combustion process or produce large fluctuations, and thus, weaken the flame stability.…”

Section: Introductionmentioning

confidence: 99%

“…The former is usually introduced by specially designed nozzle tips with magnetic or piezoelectric actuators 11,12 . The acoustic excitation is more often used and is added by loudspeakers mounted upstream of the nozzle exits [13][14][15][16][17] . The influence of this type of excitation on reduction of pollution emissions in a lean premixed lifted flames and flame stability was demonstrated by Chao et al 13,14 , among others.…”

Section: Introductionmentioning

confidence: 99%

Control of a Lifted H2/N2 Flame by Axial and Flapping Forcing: A Numerical Study

Tyliszczak

Wawrzak

2021

Preprint

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The large eddy simulation (LES) method combined with the Eulerian stochastic field approach has been used to study excited lifted hydrogen flames in a stream of hot co-flow air in a configuration closely corresponding to the so-called Cabra flame. The excitation is obtained by adding to an inlet velocity profile three types of forcing ((i) axial; (ii) flapping; (iii) combination of both) with amplitude of 15% of the fuel jet velocity and frequency corresponding to the Strouhal numbers St=0.30, 0.45, 0.60 and 0.75. It is shown that such a type of forcing significantly changes the lift-off height Lh of the flame and its global shape, resulting in a flame occupying large volume or the flame, which downstream the nozzle transforms from the circular one into a quasi-planar flame. Both the Lh and their spreading angles of the flames were found to be a function of the type of the forcing and its frequency. The minimum value of Lh has been found for the case with the combination of axial and flapping forcing at the frequency close to the preferred one in the unexcited configuration. The impact of the flapping forcing manifested through a widening of the flame in the flapping direction. It was shown that the excitation can significantly increase the level of the velocity and temperature fluctuations intensifying the mixing process. The computational results are validated based on the solutions obtained for a non-excited flame for which experimental data are available.

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Responses of a Lifted Non-Premixed Flame to Acoustic Forcing. Part 2

Cited by 12 publications

References 20 publications

Flow Structure of Swirling Turbulent Propane Flames

Flow Structure of Swirling Turbulent Propane Flames

Experimental Study of Methane Combustion Efficiency in a High-Enthalpy Oxygen-Containing Flow

Control of a Lifted H2/N2 Flame by Axial and Flapping Forcing: A Numerical Study

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