Dynamics and stability of lean-premixed swirl-stabilized combustion

Huang, Ying; Yang, Vigor

doi:10.1016/j.pecs.2009.01.002

Cited by 1,123 publications

(492 citation statements)

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“…It can occur at high Reynolds and swirl number flows [4][5][6][7][8][9][10] and its precession frequency is controlled by the rotation rate of the swirled flow [3]. Several studies show that combustion can suppress the PVC [6,7,11], but other cases also show PVCs which are present in reacting flows [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…Both phenomena, the PVC and combustion instabilities, can be simultaneously present in swirled flames and interact with each other but the link between PVC and thermoacoustics remains a controversial issue. Several studies [40,11,10] have shown that the PVC can provoke thermo-acoustic instabilities because the flame position and the recirculation zones change when the PVC is active [10,14]. Forced acoustic oscillations can also lead to a stretching and contracting of the PVC [41].…”

Section: Introductionmentioning

confidence: 99%

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Bistable swirled flames and influence on flame transfer functions

Hermeth

Staffelbach

Gicquel

et al. 2014

Combustion and Flame

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Large Eddy Simulations (LES) are used to study a lean swirl-stabilized gas turbine burner where the flow exhibits two stable states. In the first one, the flame is attached to the central bluff body upstream of the central recirculation zone which contains burnt gases. In the second one the flame is detached from the central bluff body downecirculation zone which is filled by cold unburnt gases and dominated by a strong Precessing Vortex Core (PVC). The existence of these two states has an important effect on the dynamic response of the flame (FTF): both gain and phase of the FTF change significantly in the detached case compared to the attached one, suggesting that the stability of the machine to thermoacoustic oscillations will differ, depending on the flame state. Bifurcation diagrams show that the detached flame cannot be brought back to an attached position with an increased fuel flow rate, but it can be re-attached by forcing it at high amplitudes. The attached flame however, behaves inversely: it can be brought back to the detached position by both decreasing or increasing the pilot mass flow rate, but it remains attached at all forcing amplitudes. IntroductionSwirling flows are commonly used to help flame stabilization in gas turbine combustion chambers. They feature several types of vortex breakdown and can exhibit bifurcation phenomena where different states can co-exist and the flow can jump spontaneously from one to another [1,2]. Bifurcations of flames in configurations which are close to real gas turbine chambers have not been investigated so far even though engineers report that they observe these mechanisms and that there is a link between flame states and thermoacoustic instabilities: when the flame changes from one state to another, its acoustic stability characteristics also change.Two dynamic phenomena are usually observed in swirled combustion chambers: (1) a helical flow instability, the so-called precessing vortex core (PVC) and (2) thermo-acoustic instabilites.The PVC is an hydrodynamic instability in swirling flows [3].I t is a large scale structure characterized by a regular rotation of a spiral structure around the geometrical axis of the combustion chamber. It can occur at high Reynolds and swirl number flows [4][5][6][7][8][9][10] and its precession frequency is controlled by the rotation rate of the swirled flow [3]. Several studies show that combustion can suppress the PVC [6,7,11], but other cases also show PVCs which are present in reacting flows [12][13][14][15]. The interaction of PVC with flames has been analyzed for example by Stöhr et al.[16]: they found the PVC to enhance mixing and to increase the flame surface. This was associated to structures in the inner shear layer, whereas Moeck et al. [15] observed the outer shear layer to create most of the flame perturbations. Both researchers as well as Staffelbach [13] using LES evidenced a ''finger-like'' rotating structure at the flame foot around which the PVC is turning. Furthermore, asymmetric fluctuations of the he...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bistable swirled flames and influence on flame transfer functions

Hermeth

Staffelbach

Gicquel

et al. 2014

Combustion and Flame

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“…Laminar Finite Rate, Finite Rate /Eddy Dissipation and Eddy Dissipation Concept model are the sub-grid scale combustion models provided in FLUENT code [1,2]. The Finite Rate /Eddy Dissipation model are used in this study, which uses the smaller one of Arrhenius and eddy dissipation rate as the net reaction rate [1,2].…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…To improve the combustion stabilization of lean-premixed flame, swirling flows has been widely used in the gas turbine combustion systems [1,2]. In high swirl flow conditions, the breakdown of vortex induces the formation of central toroidal recirculation zone (CTRZ) inside the combustion chamber [2].…”

Section: Introductionmentioning

confidence: 99%

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Large Eddy Simulation of the PVC Behavior in both Non-Reacting and Reacting Flows with Different Reynold Numbers

Shi¹,

Fu²,

Shen³

et al. 2016

IJHT

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The effects of the Reynold number on the precessing vortex core (PVC) behavior in both non-reacting and reacting flows are numerically studied using a three-dimensional fully compressible large eddy simulation method. The predicted results show that a central toroidal recirculation zone (CTRZ) is generated in the vicinity of the axis of the combustor which is dominated by many small-scale vortices. Meanwhile, two smaller external recirculation zones (ERZs) are established in the vicinity of the sidewall of the combustion chamber. Under combustion conditions, the flow field tends to become complex, and the structure of CTRZ is more irregular compared to that of the non-reacting flow. An increase in the inlet Reynold number enlarges the magnitude of CTRZ and thus produces a more regular and stronger structure of the PVC inside the combustion chamber. Consequently, the breakdown positon of the PVC moves downstream under higher Reynold numbers. The structure of PVCs in the reacting flow mostly located in the regions of the unburned reactants within the per-chamber which is relatively smaller and irregular compared to that in the non-reacting flow. There is a linear increase in pressure oscillations amplitude and frequency with an increase in the inlet Reynold numbers. However, the Strouhal number remains relatively constant in both non-reacting and reacting flows. There is also an anticipated decrease in pressure oscillations and frequency in the reacting flow due to the compressibility effect in the reacting flow.

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Macrostructure and NO_x emission evolution characteristics of lean‐premixed flames under combustion instability

Tao

Zhou

2020

Asia-Pacific J Chem Eng

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Effects of combustion instability on flame macrostructures and NO x emissions were conducted experimentally in a model gas turbine combustor. Two variables of the CH 4 flame were investigated-the flow rate and the equivalence ratio. Results indicate that flame macrostructure changes when the equivalence ratio increases from 0.50 to 1.00, the average total length of flame front firstly decreases from 105 to 75 mm, and then increases to 110 mm. While the average length of flame root decreases from 25 to 5 mm. The appearance of the flame front evolves from a "M" shape to a reversed "V" shape, but the appearance of the flame root changes from elongated V shape to a flatted V shape. The envelop diagram of different combustion instability signifies that there are mode shifting of flame-acoustic interactions in the combustion chamber. Under instability conditions, the temperature and velocity distribution of the flame front or flame root affects the NO x emissions. Along the radial direction, the peak temperature in the inner recirculation region and the outer recirculation region drops. This article explored the dynamic characteristics of lean-premixed flames under combustion instability, which could be instructive to the designing of stable and clean combustors in industrial gas turbines.

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Dynamics and stability of lean-premixed swirl-stabilized combustion

Cited by 1,123 publications

References 534 publications

Bistable swirled flames and influence on flame transfer functions

Bistable swirled flames and influence on flame transfer functions

Large Eddy Simulation of the PVC Behavior in both Non-Reacting and Reacting Flows with Different Reynold Numbers

Macrostructure and NO_x emission evolution characteristics of lean‐premixed flames under combustion instability

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Dynamics and stability of lean-premixed swirl-stabilized combustion

Cited by 1,123 publications

References 534 publications

Bistable swirled flames and influence on flame transfer functions

Bistable swirled flames and influence on flame transfer functions

Large Eddy Simulation of the PVC Behavior in both Non-Reacting and Reacting Flows with Different Reynold Numbers

Macrostructure and NOx emission evolution characteristics of lean‐premixed flames under combustion instability

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Macrostructure and NO_x emission evolution characteristics of lean‐premixed flames under combustion instability