The Effect of Fuel Staging on the Structure and Instability Characteristics of Swirl-Stabilized Flames in a Lean Premixed Multinozzle Can Combustor

Samarasinghe, Janith; Culler, Wyatt; Quay, Bryan D.; Santavicca, Domenic A.; O’Connor, Jacqueline

doi:10.1115/1.4037461

Cited by 37 publications

(17 citation statements)

References 22 publications

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“…The range of optimum equivalence ratio was 0.26 to 0.29, and the ratio of staged fuel was not greater than 20%. Samarasinghe et al 29 investigated the impact of fuel staging on flame instability and structure in a swirl-stabilized can combustor. They reported that fuel staging effectively curbs the instability when the overall equivalence ratio was either increased by staging or remained constant during staging.…”

Section: Combustion and Emissions Characteristicsmentioning

confidence: 99%

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

et al. 2019

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Summary The use of fossil fuel is expected to increase significantly by midcentury because of the large rise in the world energy demand despite the effective integration of renewable energies in the energy production sector. This increase, alongside with the development of stricter emission regulations, forced the manufacturers of combustion systems, especially gas turbines, to develop novel combustion techniques for the control of NOx and CO2 emissions, the latter being a greenhouse gas responsible for more than 60% to the global warming problem. The present review addresses different burner designs and combustion techniques for clean power production in gas turbines. Combustion and emission characteristics, flame instabilities, and solution techniques are presented, such as lean premixed air‐fuel (LPM) and premixed oxy‐fuel combustion techniques, and the combustor performance is compared for both cases. The fuel flexibility approach is also reviewed, as one of the combustion techniques for controlling emissions and reducing flame instabilities, focusing on the hydrogen‐enrichment and the integrated fuel‐flexible premixed oxy‐combustion approaches. State‐of‐the‐art burner designs for gas turbine combustion applications are reviewed in this study, including stagnation point reverse flow (SPRF) burner, dry low NOx (DLN) and dry low‐emission (DLE) burners, EnVironmental burners (including EV, AEV, and SEV burners), perforated plate (PP) burner, and micromixer (MM) burner. Special emphasis is made on the MM combustor technology, as one of the most recent advances in gas turbines for stable premixed flame operation with wide turndown and effective control of NOx emissions. Since the generation of pure oxygen is prerequisite to oxy‐combustion, oxygen‐separation membranes became of immense importance either for air separation for clean oxy‐combustion applications or for conversion/splitting of the effluent CO2 into useful chemical and energy products. The different carbon‐capture technologies, along with the most recent carbon‐utilization approaches towards CO2 emissions control, are also reviewed.

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Section: Combustion and Emissions Characteristicsmentioning

confidence: 99%

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

et al. 2019

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“…Experiments are conducted in a laboratory-scale fouraround-one multi-nozzle can combustor, shown in Figure 1a, which has been previously described in Refs. [21] and [22]. This combustor confines atmospheric pressure premixed natural gas-air flames anchored to annular swirler nozzles within an optically-accessible 25.4 cm diameter cylindrical quartz chamber with an open, pressure-release boundary condition at the exit.…”

Section: Experimental Configurationmentioning

confidence: 99%

“…Literature detailing the mechanism by which fuel staging stabilizes the combustor is sparse, despite the growing literature on multi-nozzle combustor systems [16][17][18][19][20]. We have previously shown that the in-phase oscillation of adjacent flames in the unstable regime suggests the presence of largescale, coherent vortical structures that convect downstream from the combustor dump plane [21]. Examination of local instantaneous heat release rate phase via chemiluminescence imaging showed these oscillations to occur in-phase with dynamic pressure sampled at the dump plate [22], illustrating two components of the instability feedback loop.…”

Section: Introductionmentioning

confidence: 99%

Flame Edge Dynamics and Interaction in a Multinozzle Can Combustor With Fuel Staging

Doleiden

Culler

Tyagi

et al. 2019

Journal of Engineering for Gas Turbines and Power

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The characterization and mitigation of thermoacoustic combustion instabilities in gas turbine engines are necessary to reduce pollutant emissions, premature wear, and component failure associated with unstable flames. Fuel staging, a technique in which the fuel flow to a multinozzle combustor is unevenly distributed between the nozzles, has been shown to mitigate the intensity of self-excited combustion instabilities in multiple nozzle combustors. In our previous work, we hypothesized that staging suppresses instability through a phase-cancelation effect in which the heat release rate from the staged nozzle oscillates out of phase with that of the other nozzles, leading to destructive interference that suppresses the instability. This previous theory, however, was based on chemiluminescence imaging, which is a line-of-sight integrated technique. In this work, we use high-speed laser-induced fluorescence to further investigate instability suppression in two staging configurations: center-nozzle and outer-nozzle staging. An edge-tracking algorithm is used to compute local flame edge displacement as a function of time, allowing instability-driven edge oscillation phase coherence and other instantaneous flame dynamics to be spectrally and spatially resolved. Analysis of flame edge oscillations shows the presence of convecting coherent fluctuations of the flame edge caused by periodic vortex shedding. When the system is unstable, these two flame edges oscillate together as a result of high-intensity longitudinal-mode acoustic oscillations in the combustor that drive periodic vortex shedding at each of the nozzle exits. In the stable cases, however, the phase between the oscillations of the center and outer flame edges is greater than 90 deg (∼114 deg), suggesting that the phase-cancelation hypothesis may be valid. This analysis allows a better understanding of the instantaneous flame dynamics behind flame edge oscillation phase offset and fuel staging-based instability suppression.

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“…Large amplitude pressure oscillations were suppressed by disrupting the formation of coherent vortices in the flow field (Paschereit & Gutmark 2006). Samarasinghe et al (2017) observed that the regions where the heat release rate were in phase with the pressure fluctuations, fluctuate out-of-phase with the pressure oscillations on the introduction of fuel staging, thereby causing suppression of thermoacoustic instability. Understanding the emergence of spatio-temporal patterns could possibly aid in the mitigation of thermoacoustic instability in turbulent combustors.…”

Section: Introductionmentioning

confidence: 99%

Pattern formation during transition from combustion noise to thermoacoustic instability via intermittency

et al. 2018

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Gas turbine engines are prone to the phenomenon of thermoacoustic instability, which is highly detrimental to their components. Recently, in turbulent combustors, it was observed that the transition to thermoacoustic instability occurs through an intermediate state, known as intermittency, where the system exhibits epochs of ordered behaviour, randomly appearing amidst disordered dynamics. We investigate the onset of intermittency and the ensuing self-organization in the reactive flow field, which, under certain conditions, could result in the transition to thermoacoustic instability. We characterize this transition from a state of disordered and incoherent dynamics to a state of ordered and coherent dynamics as pattern formation in the turbulent combustor, utilizing high-speed flame images representing the distribution of the local heat release rate fluctuations, flow field measurements (two-dimensional particle image velocimetry), unsteady pressure and global heat release rate signals. Separately, through planar Mie scattering images using oil droplets, the collective behaviour of small scale vortices interacting and resulting in the emergence of large scale coherent structures is illustrated. We show the emergence of spatial patterns using statistical tools used to study transitions in other pattern forming systems. In this paper, we propose that the intertwined and highly intricate interactions between the wide spatio-temporal scales in the flame, the flow and the acoustics are through pattern formation.

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The Effect of Fuel Staging on the Structure and Instability Characteristics of Swirl-Stabilized Flames in a Lean Premixed Multinozzle Can Combustor

Cited by 37 publications

References 22 publications

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

Flame Edge Dynamics and Interaction in a Multinozzle Can Combustor With Fuel Staging

Pattern formation during transition from combustion noise to thermoacoustic instability via intermittency

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The Effect of Fuel Staging on the Structure and Instability Characteristics of Swirl-Stabilized Flames in a Lean Premixed Multinozzle Can Combustor

Cited by 37 publications

References 22 publications

Frontiers in combustion techniques and burner designs for emissions control and CO2capture: A review

Frontiers in combustion techniques and burner designs for emissions control and CO2capture: A review

Flame Edge Dynamics and Interaction in a Multinozzle Can Combustor With Fuel Staging

Pattern formation during transition from combustion noise to thermoacoustic instability via intermittency

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Product

Resources

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Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review