Self-induced unstable behaviors of CH4 and H2/CH4 flames in a model combustor with a low-swirl injector

Therkelsen, Peter; Portillo, J. Enrique; Littlejohn, David; Martin, Scott M.; Cheng, R.K.

doi:10.1016/j.combustflame.2011.11.008

Cited by 52 publications

(20 citation statements)

References 31 publications

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“…It is shown that at such confinement ratios, enclosure or exit constriction does not significantly affect the flow-field and flame stabilization in low-swirl flames [48]. Moreover, recent results [34] show that outer recirculation zones formed in confined flames do not play a role in flame response. Birbaud et al [49] investigated effect of various confinement ratios on flame response of premixed V-flames.…”

Section: Thermoacoustic Coupling In the Flame Shear Layermentioning

confidence: 94%

“…Huang and Ratner [32] observed similar thermoacoustic coupling in the shear layer in local Rayleigh index maps for Strouhal numbers on the order of unity. Recent studies [33,34] on self-excited combustion instability of lowswirl flames in a model gas turbine combustor cite flame folding by vortices in the shear layer as a key driving mechanism of combustion instability.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Characterization of Response of Lean Premixed Low-Swirl Flames to Acoustic Excitations

Bagheri-Sadeghi

Shahsavari

Farshchi

2013

International Journal of Spray and Combustion Dynamics

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Acoustically excited lean premixed low-swirl flames were experimentally investigated to gain a better understanding of detrimental thermoacoustic couplings which can occur in applications like low-NO x gas turbines. Propane-air flames were imaged and analyzed at equivalence ratios of 0.6 to 0.8, mean flow velocities of 3.5 to 5.5 m/s and excitation frequencies of 135 Hz to 555 Hz. It was observed that with increasing excitation frequency, mean flame shape gradually became wider up to a Strouhal number of about 2.5 and then slowly reverted back to the unexcited flame shape. Such large changes in mean flame shape and possibly flow field under acoustic excitations can significantly affect flame dynamics. Increased heat release fluctuations were observed in the flame shear layer at Strouhal numbers from 1 to 2. Rolling up of the flame by vortices was suggested as a driving mechanism for these fluctuations which may lead to combustion instabilities.

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Section: Thermoacoustic Coupling In the Flame Shear Layermentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Experimental Characterization of Response of Lean Premixed Low-Swirl Flames to Acoustic Excitations

Bagheri-Sadeghi

Shahsavari

Farshchi

2013

International Journal of Spray and Combustion Dynamics

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“…За счет расширения сечения возникает внешняя зона рециркуляции тороидальной формы. Такая структура потока реализуется в горелках двух видов [3]. В первых применяются инжекторы, создающие сильно закрученный поток, что способствует распаду вихрей и формированию внутренней зоны рециркуляции в центральной области камеры.…”

Section: Doi 1015372/fgv20150404unclassified

Influence of Flow Swirling on the Aerothermodynamic Behaviour of Flames

2015

FGV

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“…A number of studies have looked at staging effects on NOx emissions (Adachi et al, 2007;Chockalingam et al, 2011;Hayashi et al, 2005;Johnson et al, 2005;Littlejohn and Cheng, 2007;Zajadatz et al, 2007), while others have investigated the thermo-acoustic instabilities in various configurations of staged burners (Barbosa et al, 2009;Fritsche et al, 2007;Martin et al, 2006;Therkelsen et al, 2013). In this study, a conceptual design of an industrial GT burner is used to investigate the effects of fuel staging and running conditions with enhanced thermo-acoustic pulsations.…”

Section: Introductionmentioning

confidence: 97%

Phase Resolved Analysis of Flame Structure in Lean Premixed Swirl Flames of a Fuel Staged Gas Turbine Model Combustor

Gounder

Boxx

Kutne

et al. 2014

Combustion Science and Technology

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A scaled model of a gas turbine (GT) burner with coaxially mounted swirlers has been used to study the effects of fuel staging on the behavior of lean premixed methane air flames. Lean flames are known to be susceptible to instabilities that can lead to unsteady operation, flame extinction, and thermo-acoustic oscillations. High speed (10 kHz) laser and optical diagnostic techniques have been used to investigate the fuel staging effect on the mechanisms involved in such instabilities. Methane air flames at atmospheric pressure have been investigated at a constant thermal power of 58 kW. The global equivalence ratio was kept constant, while the fuel staging was varied. The bulk flow velocity at the exit plane was kept constant at 20 m/s. Simultaneous high speed OH PLIF, OH * CL, and acoustic measurements were performed at kHz repetition rate to characterize the flames and determine the operability limits of the combustor. The characterization measurements reveal significant changes in flame shape for various staging ratios as well as onset of self-excited thermo-acoustics in flames with more than 55% fuel injection in the outer swirler. The phase resolved analysis of the OH * CL revealed pulsation in the heat release due to acoustics in flames with higher percentage of fuel in the outer swirler. Comparison of the pressure oscillation in the combustion chamber with the heat release yielded a clear picture regarding the feedback mechanism that sustains the self-excited thermo-acoustic pulsations. The variation of local equivalence ratio of the mixture seems to be the driving force that initiates the onset of acoustics pulsations.

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Self-induced unstable behaviors of CH4 and H2/CH4 flames in a model combustor with a low-swirl injector

Cited by 52 publications

References 31 publications

Experimental Characterization of Response of Lean Premixed Low-Swirl Flames to Acoustic Excitations

Experimental Characterization of Response of Lean Premixed Low-Swirl Flames to Acoustic Excitations

Influence of Flow Swirling on the Aerothermodynamic Behaviour of Flames

Phase Resolved Analysis of Flame Structure in Lean Premixed Swirl Flames of a Fuel Staged Gas Turbine Model Combustor

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