Experimental Investigations on the Dynamics of Pulsated Premixed Axial Jet Flames

Büchner, H.; Hirsch, Christoph; Leuckel, Wolfgang

doi:10.1080/00102209308935311

Cited by 27 publications

(12 citation statements)

References 3 publications

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“…Most descriptions of this process in combustion systems have been in terms of an empirically determined time-delay between the inlet acoustic velocity field and the overall flame heat release. Such results have been published by Merk (1967) for a bunsen-type flame, by Lawn (1982) for a small diffusion flame, by Buechner, Hirsch and Leuckel (1993) for a premixed pulse combustor, and by Bloxsidge, Dowling and Langhorne (1988) for a gutter-stabilised reheat flame, and have been reviewed by Raun et al (1993). It is frequently the case that this time-delay can be related to the time for transit at the mean velocity from the burner mouth to some significant point in the flow.…”

Section: Introductionmentioning

confidence: 60%

“…In the case of the highest frequencies examined (700-800 Hz), as many as seven cycles took place before an observed fluctuation in heat release high in the flame. This is believed to be the first time that so many cycles have been reported, although Buechner et al (1993) showed the convection effect very clearly over one cycle, correlating the convection with the burner exit velocity. In passing, it should be noted that the ability to track the disturbances through the flame suggests a crude method for measuring the mean flow velocity at different points within it.…”

Section: Convected Disturbancesmentioning

confidence: 85%

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The Acoustic Self-Excitation of a Bluff-Body Stabilised, Premixed Flame

Lawn

2000

Combustion Science and Technology

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The objective of this investigation in a laboratory combustion system was to understand why a premixed propane flame is acoustically excited with particular acoustic boundary conditions, in particular regions of the frequency spectrum. h was demonstrated that the phase of the heat release at various heights in the flame relative to the burner exit velocity indicated a disturbance with a time-delay related to convection by the mean flow from the moment that it left the burner mouth. This gave rise to both positive and negative contributions to acoustic energy flux (the Rayleigh integral) from different heights in the flame, in some cases over as many as seven cycles. Thus. some thermo-acoustic eigen-frequencies were not strongly excited. even when local contributions were high. Conversely, the coincidence of a Helmholtz resonance (low acoustic pressure fluctuations associated with high acoustic velocity fluctuations) in the premixture supply system with a combustion chamber quarter-wave resonance (high acoustic pressures) made it impossible to stabilise the flame.

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Section: Introductionmentioning

confidence: 60%

Section: Convected Disturbancesmentioning

confidence: 85%

The Acoustic Self-Excitation of a Bluff-Body Stabilised, Premixed Flame

Lawn

2000

Combustion Science and Technology

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“…However, the convection process is governed by input parameters and the geometry of the nozzle. The distance between the edge of the centerbody and the maximum CH* chemiluminescence intensity location plays a critical role in combustion instability, since the convection time scale is determined by the distance, L CH*max [27,[29][30]. Fig.…”

Section: Self-excited Instability Measurementmentioning

confidence: 99%

“…The phase of the flame transfer function provides convection times needed for the flame to respond to upstream disturbance. The overall time delay consists of a characteristic time delay for the convective transport of the fuel/air mixture from the combustor inlet to the reaction zone, a time delay for the heating of the mixture to ignition temperature, and a characteristic kinetic time delay for the chemical reaction [30]. The phase of the flame transfer function includes these three characteristic time scales.…”

Section: Self-excited Instability Measurementmentioning

confidence: 99%

Linear stability analysis of acoustically driven pressure oscillations in a lean premixed gas turbine combustor

Kim

Santavicca

2009

J Mech Sci Technol

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The dynamic response of a turbulent premixed flame to acoustic velocity perturbations was experimentally determined in a swirl-stabilized lean-premixed gas turbine combustor. CH* chemiluminescence intensity and the twomicrophone method were used to measure heat release rates and inlet velocity fluctuations, respectively. Using the n-τ formulation, gain and phase of flame transfer functions were incorporated into an analytic thermoacoustic model to predict instability frequencies and modal structures. Self-excited instability measurements were performed to verify eigenfrequencies predicted by the thermoacoustic model. Instability frequency predicted by the model is supported by experimental results. Results show that the self-excited instability frequency of ~ 220 Hz results from the fact that the flames amplify flow perturbations with f = 150 ~ 250 Hz. The other instability frequency of ~ 350 Hz occurs because the whole combustion system has an eigenfrequency corresponding to the ¼-wave eigenmode of the mixing section.

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“…One of them is the heat release rate and the chemiluminescent emissions have been usually used to provide qualitative information about it. [26][27][28][29][30][31][32][33][34] Kinetic modeling is a diagnostic tool that could help in the interpretation of the chemiluminescence signals to achieve qualitative and quantitative information on parameters as combustion chemistry and heat release rates.…”

Section: Introductionmentioning

confidence: 99%

Temperature measurements by oh lif and chemiluminescence kinetic modeling for ethanol flames

Marques¹,

Santos²,

Sbampato³

et al. 2009

Quím. Nova

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Rod. dos Tamoios, km 5,5, 12228-001 São José dos Campos -SP, BrasilRecebido em 21/10/08; aceito em 4/5/09; publicado na web em 1/10/09 TEMPERATURE MEASUREMENTS BY OH LIF AND CHEMILUMINESCENCE KINETIC MODELING FOR ETHANOL FLAMES. OH LIF-thermometry was applied to premixed ethanol flames at atmospheric pressure in a burner for three flame conditions. Flame temperatures were simulated from energy equation with PREMIX code of CHEMKIN software package for comparison. A kinetic modeling based on a model validated through chemiluminescence measurements and on a set of reactions for nitrogen chemistry was evaluated. Marinov's mechanism was also tested. Sensitivity analysis was performed for fuel-rich flame condition with F = 1.34. Simulated temperatures from both reaction mechanisms evaluated were higher than experimental values. However, the proposed kinetic modeling resulted in temperature profiles qualitatively very close to the experimental.

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Experimental Investigations on the Dynamics of Pulsated Premixed Axial Jet Flames

Cited by 27 publications

References 3 publications

The Acoustic Self-Excitation of a Bluff-Body Stabilised, Premixed Flame

The Acoustic Self-Excitation of a Bluff-Body Stabilised, Premixed Flame

Linear stability analysis of acoustically driven pressure oscillations in a lean premixed gas turbine combustor

Temperature measurements by oh lif and chemiluminescence kinetic modeling for ethanol flames

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