Fuel Flexibility Influences on Premixed Combustor Blowout, Flashback, Autoignition, and Stability

Lieuwen, Tim; McDonell, Vince; Petersen, Eric L.; Santavicca, Domenic A.

doi:10.1115/1.2771243

Cited by 267 publications

(130 citation statements)

References 45 publications

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“…Under a high ambient temperature of 1000 K, Figure 4 demonstrated that combustion recession appears as a connected, backward-traveling wave possibly driven by flame propagation processes. But, the speed of combustion recession for this condition is approximately 200 m/s and is much faster than gas-turbine studies that measured flashback speeds on the order of typical turbulent flame speeds [30,31]. Furthermore, as the ambient temperature was reduced to 900 K in Figure 4, combustion recession appeared as isolated ignition sites that merged with time, which is inconsistent with the concept of a propagating flame sheet.…”

Section: Description Of Combustion Recession Based On Measurements Anmentioning

confidence: 41%

Combustion Recession after End of Injection in Diesel Sprays

Knox¹,

Genzale²,

Pickett³

et al. 2015

SAE Int. J. Engines

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This work contributes to the understanding of physical mechanisms that control flashback, or more appropriately combustion recession, in diesel-like sprays. Combustion recession is the process whereby a lifted flame retreats back towards the injector after end-of-injection under conditions that favor autoignition. The motivation for this study is that failure of combustion recession can result in unburned hydrocarbon emissions.A large dataset, comprising many fuels, injection pressures, ambient temperatures, ambient oxygen concentrations, ambient densities, and nozzle diameters is used to explore experimental trends for the behavior of combustion recession. Then, a reduced-order model, capable of modeling non-reacting and reacting conditions, is used to help interpret the experimental trends. Finally, the reduced-order model is used to predict how a controlled ramp-down rate-ofinjection can enhance the likelihood of combustion recession for conditions that would not normally exhibit combustion recession.In general, fuel, ambient conditions, and the spray rate-of-injection transient during the end-of-injection determine the success or failure of combustion recession. The likelihood of combustion recession increases for higher ambient temperatures and oxygen concentrations as well as for higher reactivity fuels. In the transition between high and low ambient temperature (or oxygen concentration), the behavior of combustion recession changes from spatially sequential ignition to separated, or isolated, ignition sites that eventually merge. In contradistinction to typical diesel ignition delay trends where the autoignition times are longer for increasing injection pressure, the time required for combustion recession increases with injection pressure.

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Section: Description Of Combustion Recession Based On Measurements Anmentioning

confidence: 41%

Combustion Recession after End of Injection in Diesel Sprays

Knox¹,

Genzale²,

Pickett³

et al. 2015

SAE Int. J. Engines

View full text Add to dashboard Cite

show abstract

“…Additionally, although some attentions have been devoted on the effect of fuel type in combustion instability [16][17][18] and combustion noise [19], no work has been focused on the transmitted noise rising from a burned gases of a traditional or novel composite fuel in an exit combustor nozzle; as the whole above studies applied hot air as the working fluid. These conditions, however, are really found in an exit nozzle of a combustor in industrial or aero-engine gas turbines.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the transmitted noise of a combustor exit nozzle caused by burned hydrogen-hydrocarbon gases

Hosseinalipour

Fattahi

Karimi

2016

International Journal of Hydrogen Energy

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Transmitted noise is a major problem in industrial and aero-engine gas turbines. One of a noise generating part in the preceding systems is exit nozzle which can play as encouraging or discouraging sound waves. The generated noise may arise from an incident acoustic wave or entropy wave. In this paper, the effect of heat transfer and inlet Mach number of the exit nozzle as well as replacing the traditional hydrocarbon fuels with hydrogen and composite of hydrogen-hydrocarbon on noise generation is studied. Further, the influence of the hydrodynamic decaying mechanisms in a nozzle on the noise generated by entropy waves is investigated. It is found that hydrogen can reduce transmitted noise in a subcritical nozzle with an acoustic incident wave or in a supercritical nozzle with an incident entropic wave.

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“…Most operating conditions have been shown to influence the thermo-acoustic stability of the combustor. Equivalence ratio as well as fuel composition, mixture preheat temperature, and other flow properties like swirl and Reynolds numbers' effect on dynamic instabilities have been investigated [1][2][3][4][5][6][7][8]. Because of its critical importance, thermoacoustic instabilities arising in premixed combustion have been extensively studied for decades and are still an active area of research.…”

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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Fuel Flexibility Influences on Premixed Combustor Blowout, Flashback, Autoignition, and Stability

Cited by 267 publications

References 45 publications

Combustion Recession after End of Injection in Diesel Sprays

Combustion Recession after End of Injection in Diesel Sprays

Investigation of the transmitted noise of a combustor exit nozzle caused by burned hydrogen-hydrocarbon gases

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

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