Experimental and numerical investigation of two flame stabilization regimes observed in a dual swirl H<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si50.svg"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>-air coaxial injector

Aniello, A.; Laera, Davide; Marragou, Sylvain; Magnes, Hervé; Selle, Laurent; Schuller, Thierry; Poinsot, Thiérry

doi:10.1016/j.combustflame.2022.112595

Cited by 26 publications

(10 citation statements)

References 56 publications

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“…3(a). This flame archetype was already observed in the previous version of the burner [20,25]. Zone 2 is observed for higher fuel mass flow rates ṁH 2 than Zone 1 and for air mass flow rates ṁair higher than 1.3 g/s for this geometrical configuration of the HYLON injector.…”

Section: Flame Stabilizationsupporting

confidence: 81%

“…Hence, the flame stabilization mode, the air and hydrogen injections velocities, alter the NO x emissions. More recently, Marragou et al [26] identified the edge flame displacement of the diffusion branch as the controlling mechanism for flame re-anchoring that was also corroborated by numerical flow simulations [25].…”

Section: Introductionmentioning

confidence: 70%

“…Figure 1(a) shows the test rig and the HYLON burner, which is an optimized version of the one investigated in [20,25,26]. The test bench is used to stabilize H 2 -air swirled flames with the objective to minimize the pressure losses through the injector and the range of operating conditions with lifted flames.…”

Section: Methodsmentioning

confidence: 99%

“…A recent numerical study from Aniello et al [25] considers the HYLON injector and scrutinizes the flame structure and the stabilization mechanisms for the aforementioned regimes. They showed that H 2 attached flames are entirely governed by diffusion, while lifted flames present a central diffusion branch accompanied by a lateral partially premixed flame wing.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Impact of Preheating on Flame Stabilization and NOx Emissions From a Dual Swirl Hydrogen Injector

Magnes,

Marragou,

Aniello

et al. 2023

Volume 3B: Combustion, Fuels, and Emissions

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Flame stabilization, structure and pollutant emissions are investigated experimentally on a swirled injection system operating with globally lean air/hydrogen mixtures at atmospheric conditions and moderate Reynolds numbers. This injector consists of two coaxial ducts with separate injection of hydrogen into a central channel and of air into an annular channel. Both streams are swirled. The resulting flames exhibit two stabilization modes. In one case, the flame takes an M-shape and is anchored to the hydrogen injector lips. In the second case, the flame is aerodynamically stabilized above the injector and takes a V-shape. Regions of existence of each stabilization mode are determined according to the operating conditions. For low air flow rates, the flame can be either anchored or lifted above the hydrogen injector lips depending on the path followed to reach the operating condition. At high air flow rates, the flame is always lifted regardless of the trajectory followed. The impact of air inlet temperature on these stabilization regimes is then evaluated from T = 300 K up to 770 K. Flame re-attachment is shown to be controlled by edge flame propagation and the impact of preheating is well reproduced by the model. Unburnt hydrogen and NOx emissions are finally evaluated. Unburnt hydrogen is only observed for global equivalence ratios below 0.4 and at ambient inlet temperature. NOx emissions decrease when the global equivalence ratio is reduced. Furthermore, at fixed global equivalence ratio, NOx emissions decrease as the thermal power increases, regardless of air preheating and the flame stabilization regime. At high power, NOx emissions reach an asymptotic value that is independent of the thermal power. The impact of flame shape, air preheating and combustion chamber wall heat losses on NOx production is also evaluated. Finally, NOx emissions are shown to scale with the adiabatic flame temperature Tad at the global equivalence ratio and the global residence time inside the combustor.

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Section: Flame Stabilizationsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Impact of Preheating on Flame Stabilization and NOx Emissions From a Dual Swirl Hydrogen Injector

Magnes,

Marragou,

Aniello

et al. 2023

Volume 3B: Combustion, Fuels, and Emissions

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“…As a promising technique to decarbonising the existing gas turbine engines, direct injection (or addition in a non-premixed way) of hydrogen has gained much attention 8,9 . Thus, understanding the interaction between hydrogen diffusion flame and vortical structures in turbulent flow is necessary for such techniques to be applied in next-generation gas turbines.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulations of the Taylor-Green Vortex interacting with a hydrogen diffusion flame: Reynolds number and non-unity Lewis number effects

Xu¹,

Chen²

2023

Preprint

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Understanding the interactions between hydrogen flame and turbulent vortices is important for developing the next-generation carbon neutral combustion systems.In the present work, we perform several direct numerical simulation (DNS) cases to study the dynamics of a hydrogen diffusion flame embedded in the Taylor-Green Vortex (TGV). The evolution of flame and vortex is investigated for a range of initial Reynolds numbers up to 3200 with different mass diffusion models. We show that the vortices dissipate rapidly in cases at low Reynolds numbers, while the consistent stretching, splitting and twisting of vortex tubes are observed in cases with evident turbulence transition at high Reynolds numbers. Regarding the interactions between the flame and vortex, it is demonstrated that the heat release generated by the flame has suppression effects on the turbulence intensity and its development of the TGV.Meanwhile, the intense turbulence provides abundant kinetic energy, accelerating the mixing of the diffusion flame with a contribution to higher strain rate and larger curvatures of the flame. Considering the effects of non-unity Lewis number, it is revealed that the flame strength is more intense in the cases with mixture averaged model. However, this effect is relatively suppressed under the impacts of the intense turbulence.

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Effects of Hydrogen Enrichment on Thermoacoustic and Helical Instabilities in Swirl Stabilised Partially Premixed Flames

Kumar,

Massey,

Boxx

et al. 2023

Flow Turbulence Combust

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The effects of hydrogen enrichment on flame and flow dynamics of a swirl-stabilised partially premixed methane-air flame are studied using large eddy simulation. The sub-grid reaction rate is modelled using unstrained premixed flamelets and a presumed joint probability density function approach. Two cases undergoing thermoacoustic oscillations at ambient conditions are studied. The addition of hydrogen modifies both thermoacoustic and fluid dynamical characteristics. The amplitude of the fundamental thermoacoustic mode increases with the addition of 20% hydrogen by volume. A second pressure mode associated with the chamber mode is also excited with the hydrogen addition. Intermittent single, double and triple helical instabilities are observed in the pure methane case, but are suppressed substantially with hydrogen addition. The results are analysed in detail to shed light on these observations. The feedback loop responsible for the thermoacoustic instability is driven by mixture fraction perturbations resulting from the unequal impedances of the fuel and air channels. It is shown that hydrogen addition increases the flame’s sensitivity to these perturbations, resulting in an increase in amplitude. This higher amplitude thermoacoustic oscillation, along with a higher local heat release rate in the presence of hydrogen, is shown to considerably modify the flow structures, leading to a suppression of the helical instabilities.

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Experimental and numerical investigation of two flame stabilization regimes observed in a dual swirl H2-air coaxial injector

Cited by 26 publications

References 56 publications

Impact of Preheating on Flame Stabilization and NOx Emissions From a Dual Swirl Hydrogen Injector

Impact of Preheating on Flame Stabilization and NOx Emissions From a Dual Swirl Hydrogen Injector

Direct numerical simulations of the Taylor-Green Vortex interacting with a hydrogen diffusion flame: Reynolds number and non-unity Lewis number effects

Effects of Hydrogen Enrichment on Thermoacoustic and Helical Instabilities in Swirl Stabilised Partially Premixed Flames

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