Combustion of hydrogen-enriched methane in a lean premixed swirl-stabilized burner

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

doi:10.1016/s1540-7489(02)80108-0

Cited by 338 publications

(145 citation statements)

References 9 publications

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“…The increase in hydrogen content from 80% to 100% results in a significant shift in flame blowout conditions to leaner fuel/air ratios. This shift is consistent with studies in the literature showing an increase in the lean flammability limits with the addition of small amounts (<40%) of hydrogen to methane (Wicksall, and Agrawal, 2001;Schefer et al, 2002) and verifies that H 2 addition significantly extends lean flame stability even at the higher percentages considered here. For example, at a velocity of 50 m/s (164 ft/s), increasing n H2 from 0.8 to 1.0 reduces the equivalence ratio at flame blowout from φ =0.86 to 0.58.…”

Section: Unconfined Flame Configurationsupporting

confidence: 92%

Evaluation of NASA Lean Premixed Hydrogen Burner

Schefer¹

2003

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The stability characteristics of a prototype premixed, hydrogen-fueled burner were studied. The potential application is the use of hydrogen as a fuel for aircraft gas turbine operation. The burner configuration consisted of nine 6.72 mm (0.265 in) diameter channels through which the reactants entered the burner. Hydrogen was injected radially inward through two 0.906-mm (0.0357 in) diameter holes located on opposite sides of each air channel. In this way the region over which hydrogen and air were premixed was minimized to prevent potential flashback problems. All tests were carried out at atmospheric pressure. Flame stability was studied over a range of fuel-lean operating conditions since lean combustion is currently recognized as an effective approach to NO x emissions reduction. In addition to pure hydrogen and air, mixtures of hydrogen-blended methane and air were studied to evaluate the potential improvements in flame stability as hydrogen replaces methane as the primary fuel component.4

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Section: Unconfined Flame Configurationsupporting

confidence: 92%

Evaluation of NASA Lean Premixed Hydrogen Burner

Schefer¹

2003

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“…These flame brush distributions, which we refer to as macroscale structures or simply macrostructures, have also been previously reported as a function of different operating conditions. Schefer et al reported the dependency of flame macrostructures on fuel composition through hydrogen addition to a premixed air-methane mixture [11]. Chterev et al explored the effect of equivalence ratio and preheat temperature as well as geometrical features like the swirl number and the centerbody design on the different mean flame configurations [12,13].…”

Section: Introductionmentioning

confidence: 99%

Correspondence Between “Stable” Flame Macrostructure and Thermo-acoustic Instability in Premixed Swirl-Stabilized Turbulent Combustion

Taamallah¹,

LaBry²,

Shanbhogue³

et al. 2015

Journal of Engineering for Gas Turbines and Power

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In this paper, we conduct an experimental investigation to study the link between the flame macroscale structure-or flame brush spatial distribution-and thermo-acoustic instabilities, in a premixed swirl-stabilized dump combustor. We operate the combustor with premixed methane-air in the range of equivalence ratio (/) from the lean blowout limit to / ¼ 0:75. First, we observe the different dynamic modes in this lean range as / is raised. We also document the effect of / on the flame macrostructure. Next, we examine the correspondence between dynamic mode transitions and changes in flame macrostructure. To do so, we modify the combustor length-by downstream truncationwithout changing the underlying flow upstream. Thus, the resonant frequencies of the geometry are altered allowing for decoupling the heat release rate fluctuations and the acoustic feedback. Mean flame configurations in the modified combustor and for the same range of equivalence ratio are examined, following the same experimental protocol. It is found that not only the same sequence of flame macrostructures is observed in both combustors but also that the transitions occur at a similar set of equivalence ratio. In particular, the appearance of the flame in the outside recirculation zone (ORZ) in the long combustor-which occurs simultaneously with the onset of instability at the fundamental frequency-happens at similar / when compared to the short combustor, but without being in latter case accompanied by a transition to thermo-acoustic instability. Then, we interrogate the flow field by analyzing the streamlines, mean, and rms velocities for the nonreacting flow and the different flame types. Finally, we focus on the transition of the flame to the ORZ in the acoustically decoupled case. Our analysis of this transition shows that it occurs gradually with an intermittent appearance of a flame in the ORZ and an increasing probability with /. The spectral analysis of this phenomenon-we refer to as "ORZ flame flickering"-shows the presence of unsteady events occurring at two distinct low frequency ranges. A broad band at very low frequency in the range $(1 Hz-10 Hz) associated with the expansion and contraction of the inner recirculation zone (IRZ) and a narrow band centered around 28 Hz which is the frequency of rotation of the flame as it is advected by the ORZ flow.

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“…Experimental and computational studies performed in simplified flow configurations (freely and spherically propagating flames, counterflow flames, Bunsen-type and slot burners) have shown that the hydrogen addition to methane increases the laminar burning velocity (i.e., the flame reactivity) [5][6][7][8][9][10], the resistance to strain extinction [1,[5][6][7]9,11] and the flame front wrinkling (i.e., the flame surface area) [4,7], thus enhancing robustness and stability of the flame. These positive effects have been attributed to the increase in both flame temperature (thermal effects) and supply of active radicals (chemical effects).…”

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

133

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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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Combustion of hydrogen-enriched methane in a lean premixed swirl-stabilized burner

Cited by 338 publications

References 9 publications

Evaluation of NASA Lean Premixed Hydrogen Burner

Evaluation of NASA Lean Premixed Hydrogen Burner

Correspondence Between “Stable” Flame Macrostructure and Thermo-acoustic Instability in Premixed Swirl-Stabilized Turbulent Combustion

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

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