Stabilization mechanism of turbulent premixed flames in strongly swirled flows

Biagioli, Fernando

doi:10.1080/13647830500448347

Cited by 37 publications

(34 citation statements)

References 20 publications

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“…After the sudden expansion into the combustion chamber (about 1:4 in area), recirculation zones are formed in the central and in the outer regions. These are confirmed by numerical simulations Biagioli 2006), as well as by LDA measurements in water flow experiments (Paschereit et al 1999) and by PIV measurements (Schuermans et al 2006). A section of the combustion chamber, from the burner exit plane to about one chamber diameter downstream, is made of UV transparent quartz glass and cooled by air.…”

Section: Experimental Set-upsupporting

confidence: 66%

“…To simplify the analysis, the (time-averaged) flow direction is supposed to be parallel to this axis. Actually, this is not the case for the flow field of the investigated burner, as there is non-negligible radial in-flow of reactants towards the center of the combustor, as was confirmed by LES calculations (Biagioli 2006). However, considering the whole CZ, as it was defined above, we may assume that this inflow of reactants into CZ in transverse direction is small compared to the in-flow in axial direction.…”

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confidence: 80%

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Thermoacoustically driven flame motion and heat release variation in a swirl-stabilized gas turbine burner investigated by LIF and chemiluminescence

et al. 2008

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Laser-induced fluorescence and chemiluminescence, both phase-locked to the dominant acoustic oscillation, are used to investigate phenomena related to thermoacoustic instability in a swirl-stabilized industrial scale gas turbine burner. The observed sinusoidal phaseaveraged flame motion in axial (main flow) direction is analyzed using different schemes for defining the flame position. Qualitative agreement between experimental data and theoretical analysis of the observed flame motion is obtained, interpreted as originating primarily from variation of the burning velocity. The heat release variation during an acoustic cycle is determined from the sinusoidally varying total OH* chemiluminescence intensity.

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Section: Experimental Set-upsupporting

confidence: 66%

mentioning

confidence: 80%

Thermoacoustically driven flame motion and heat release variation in a swirl-stabilized gas turbine burner investigated by LIF and chemiluminescence

et al. 2008

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“…An example of this discrepancy is the combustion in a swirled flow studied in [29]. The flame here is stabilized by a vortex break-down system and the salient feature of combustion is a sudden displacement of the flame initially anchored by the back part of the central recirculation zone, then moving deeply into the burner and finally becoming anchored in the front part of it.…”

Section: Joint Rans/les Formulation Of the Problemmentioning

confidence: 96%

“…It is shown that LES can reproduce the flame behaviour across the full operating range, while the steady-state RANS model is not adequate. This deficiency is explained in [29] as that the RANS simulations used k-ε model, which cannot predict correctly the velocity swirl flow field in the burner. Obviously, the joint RANS/LES approach is not applicable to this case, at least, not with the standard k-ε turbulence model.…”

Section: Joint Rans/les Formulation Of the Problemmentioning

confidence: 96%

Joint RANS/LES Approach to Premixed Flame Modelling in the Context of the TFC Combustion Model

Zimont

Battaglia

2006

Flow Turbulence Combust

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We present an original timesaving joint RANS/LES approach to simulate turbulent premixed combustion. It is intended mainly for industrial applications where LES may not be practical. It is based on successive RANS/LES numerical modelling, where turbulent characteristics determined from RANS simulations are used in LES equations for estimation of the subgrid chemical source and viscosity. This approach has been developed using our TFC premixed combustion model, which is based on a generalization of the Kolmogorov's ideas. We assume existence of small-scale statistically equilibrium structures not only of turbulence but also of the reaction zones. At the same time, non-equilibrium large-scale structures of reaction sheets and turbulent eddies are described statistically by model combustion and turbulence equations in RANS simulations or follow directly without modelling in LES. Assumption of small-scale equilibrium gives an opportunity to express the mean combustion rate (controlled by small-scale coupling of turbulence and chemistry) in the RANS and LES sub-problems in terms of integral or subgrid parameters of turbulence and the chemical time, i.e. the definition of the reaction rate is similar to that of the mean dissipation rate in turbulence models where it is expressed in terms of integral or subgrid turbulent parameters. Our approach therefore renders compatible the combustion and turbulent parts of the RANS and LES sub-problems and yields reasonable agreement between the RANS and averaged LES results. Combining RANS simulations of averaged fields with LES method (and especially coupled and acoustic codes) for simulation of corresponding nonstationary process (and unsteady combustion regimes) is a promising strategy for industrial applications. In this work we present results of simulations carried out employing the joint 306 Flow Turbulence Combust (2006) 77: 305-331 RANS/LES approach for three examples: High velocity premixed combustion in a channel, combustion in the shear flow behind an obstacle and the impinging flame (a premixed flame attached to an obstacle).

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“…The present work, thus, is oriented in this direction. A few earlier studies [12,15,16] hint that the reaction closures applied in RANS may have direct applicability in the context of LES too. However, whether such adopted reaction closures shall be globally valid requires thorough examination, over a variety of flame configurations.…”

Section: Introductionmentioning

confidence: 98%

Large-Eddy Simulation of Lean Premixed Turbulent Flames of Three Different Combustion Configurations using a Novel Reaction Closure

Aluri

Muppala²,

Dinkelacker

2007

Flow Turbulence Combust

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This large eddy simulation (LES) study is applied to three different premixed turbulent flames under lean conditions at atmospheric pressure. The hierarchy of complexity of these flames in ascending order are a simple Bunsen-like burner, a suddenexpansion dump combustor, and a typical swirl-stabilized gas turbine burner-combustor. The purpose of this paper is to examine numerically whether the chosen combination of the Smagorinsky turbulence model for sgs fluxes and a novel turbulent premixed reaction closure is applicable over all the three combustion configurations with varied degree of flow and turbulence. A quality assessment method for the LES calculations is applied. The cold flow data obtained with the Smagorinsky closure on the dump combustor are in close proximity with the experiments. It moderately predicts the vortex breakdown and bubble shape, which control the flame position on the double-cone burner. Here, the jet break-up at the root of the burner is premature and differs with the experiments by as much as half the burner exit diameter, attributing the discrepancy to poor grid resolution. With the first two combustion configurations, the applied subgrid reaction model is in good correspondence with the experiments. For the third case, a complex swirl-stabilized burner-combustor configuration, although the flow field inside the burner is only modestly numerically explored, the level of flame stabilization at the junction of the burner-combustor has been rather well captured. Furthermore, the critical flame drift from the combustor into the burner was possible to capture in the LES context (which was not possible with the RANS plus k-ɛ model), however, requiring tuning of a prefactor in the reaction closure.

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Stabilization mechanism of turbulent premixed flames in strongly swirled flows

Cited by 37 publications

References 20 publications

Thermoacoustically driven flame motion and heat release variation in a swirl-stabilized gas turbine burner investigated by LIF and chemiluminescence

Thermoacoustically driven flame motion and heat release variation in a swirl-stabilized gas turbine burner investigated by LIF and chemiluminescence

Joint RANS/LES Approach to Premixed Flame Modelling in the Context of the TFC Combustion Model

Large-Eddy Simulation of Lean Premixed Turbulent Flames of Three Different Combustion Configurations using a Novel Reaction Closure

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