The interaction of flame and flow field in a lean premixed swirl-stabilized combustor operated on H2/CH4/air

Wicksall, Donald M.; Agrawal, Ajay K.; Schefer, Robert W.; Keller, Jay O.

doi:10.1016/j.proci.2004.07.021

Cited by 68 publications

(27 citation statements)

References 12 publications

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“…It was found that the LBO limit depends on aerodynamical parameters including swirl number [2][3][4] and sense of secondary swirl [2]. Furthermore the LBO limit can be extended to lower equivalence ratios through the injection of pilot fuel/air [5], addition of hydrogen [6][7][8] or an increase of preheat temperature [2,9], whereas the influence of pressure has been found to be small [7]. During operation, the proximity to LBO is currently determined on the basis of empirical quantities, which are mostly based on the intensity of low-frequency combustion oscillations [10][11][12][13] and require careful calibration before operation.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of lean blowout of a swirl-stabilized flame in a gas turbine model combustor

Stöhr

Boxx

Carter

et al. 2011

Proceedings of the Combustion Institute

212

119

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Lean blowout (LBO) of a partially premixed swirl flame is studied using chemiluminescence imaging and simultaneous stereo-PIV and OH-PLIF measurements at repetition rates up to 5 kHz. The flame, which is operated with methane and air in a gas turbine model combustor at atmospheric pressure, features a pronounced precessing vortex core (PVC) at the inner shear layer. In the first part of the study, the stabilization mechanism of the flame close to LBO is investigated. The fields of velocity and OH show that near LBO there are essentially two regions where reaction takes place, namely the helical zone along the PVC and the flame root around the lower stagnation point. The zone along the PVC is favorable to the flame due to low strain rates in the vortex center and accelerated mixing of burned and fresh gas. The flame root, which is located close to the nozzle exit, is characterized by an opposed flow of hot burned gas and relatively fuel-rich fresh gas. Due to the presence of high strain rates, the flame root is inherently unstable near LBO, featuring frequent extinction and re-ignition. The blowout process, discussed in the second part of the study, starts when the extinction of the flame root persists over a critical length of time. Subsequently, the reaction in the helical zone can no longer be sustained and the flame finally blows out. The results highlight the crucial role of the flame root, and suggest that well-aimed modifications of flow field or mixture fraction in this region might shift the LBO limit to leaner conditions.

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Section: Introductionmentioning

confidence: 99%

Dynamics of lean blowout of a swirl-stabilized flame in a gas turbine model combustor

Stöhr

Boxx

Carter

et al. 2011

Proceedings of the Combustion Institute

212

119

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“…However, the practical use of hydrogen-methane blends is yet limited. This is due to a lack in the knowledge about the mechanisms of dynamic interaction between hydrogen-enriched flames and turbulent flow fields [12], which control premixed flame propagation in combustors, industrial burners and engines [see, e.g., [13][14][15][16][17] as well as in gas explosions [see, e.g., 18,19].…”

Section: Introductionmentioning

confidence: 99%

Time-Resolved Particle Image Velocimetry of dynamic interactions between hydrogen-enriched methane/air premixed flames and toroidal vortex structures

Sarli

Benedetto

Long

et al. 2012

International Journal of Hydrogen Energy

126

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Additional Information:• NOTICE: this is the author's version of a work that was accepted for publication in the International Journal of Hydrogen Energy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was sub- Regardless of the mixture stoichiometry, the hydrogen substitution to methane leads to a transition from a regime in which the vortex only wrinkles the flame front (x H2 < 0.2) to a * Corresponding author. Phone: +39 0817622673; Fax: +39 0817622915; E-mail address: valeria.disarli@irc.cnr.it 3 more vigorous regime in which the interaction almost results in the separation of small flame pockets from the main front (x H2 > 0.2). This transition was characterised in terms of time histories of flame surface area and burning rate.

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“…Flows with backward facing steps [15,16], pilot flames [17][18][19], swirl [20,21], as well as V-shaped flames with rod-stabilization [22,23], have achieved modest to high levels of turbulence. There are several significant experimental configurations [24][25][26] that utilize strong swirl, recirculation and wall bounded flow to stabilize low Damköhler (Da) number premixed combustion, simulating the strongly swirling flow field features typically found in gas turbine combustors. Utilizing significant preheating and strong swirl to stabilize combustion in a model lean premixed gas turbine combustor, Dinkelacker et al [27] found a trend of instantaneous flame front thinning with increased turbulence intensity.…”

Section: Introductionmentioning

confidence: 99%

Finite Rate Chemistry Effects in Highly Sheared Turbulent Premixed Flames

Dunn

Masri

Bilger

et al. 2010

Flow Turbulence Combust

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Detailed scalar structure measurements of highly sheared turbulent premixed flames stabilized on the piloted premixed jet burner (PPJB) are reported together with corresponding numerical calculations using a particle based probability density function (PDF) method. The PPJB is capable of stabilizing highly turbulent premixed jet flames through the use of a small stoichiometric pilot that ensures initial ignition of the jet and a large shielding coflow of hot combustion products. Four lean premixed methane-air flames with a constant jet equivalence ratio are studied over a wide range of jet velocities. The scalar structure of the flames are examined through high resolution imaging of temperature and OH mole fraction, whilst the reaction rate structure is examined using simultaneous imaging of temperature and mole fractions of OH and CH 2 O. Measurements of temperature and mole fractions of CO and OH using the Raman-Rayleigh-LIF-crossed plane OH technique are used to examine the flame thickening and flame reaction rates. It is found that as the shear rates increase, finite-rate chemistry effects manifest through a gradual decrease in reactedness, rather than the abrupt localized extinction observed in nonpremixed flames when approaching blow-off. This gradual decrease in reactedness is accompanied by a broadening in the reaction zone which is consistent with the view that turbulence structures become embedded within the instantaneous flame front. Numerical predictions using a particle-based PDF model are shown to be able to Submitted to the Special Issue of Flow, Turbulence and Combustion dedicated to S.B. Pope. 622Flow Turbulence Combust (2010) 85:621-648 predict the measured flames with significant finite-rate chemistry effects, albeit with the use of a modified mixing frequency.

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The interaction of flame and flow field in a lean premixed swirl-stabilized combustor operated on H2/CH4/air

Cited by 68 publications

References 12 publications

Dynamics of lean blowout of a swirl-stabilized flame in a gas turbine model combustor

Dynamics of lean blowout of a swirl-stabilized flame in a gas turbine model combustor

Time-Resolved Particle Image Velocimetry of dynamic interactions between hydrogen-enriched methane/air premixed flames and toroidal vortex structures

Finite Rate Chemistry Effects in Highly Sheared Turbulent Premixed Flames

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