Impact of wall heat transfer in Large Eddy Simulation of flame dynamics in a swirled combustion chamber

Agostinelli, Pasquale Walter; Laera, Davide; Boxx, Isaac; Gicquel, Laurent; Poinsot, Thiérry

doi:10.1016/j.combustflame.2021.111728

Cited by 29 publications

(22 citation statements)

References 72 publications

(144 reference statements)

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“…Figure 5 shows a sketch of the computational domain and mesh topology. Our mesh has comparable resolution as the optimized one from Agostinelli et al 38 used at the same case showing very good reproduction 36 of the experimental data. A further refinement of up to 0.25 mm in the flame zone could not improve the overall flame shape, heat release and dynamic behavior noticeably.…”

Section: Meshmentioning

confidence: 63%

“…For this case the swirler produces most of the turbulence and a turbulent inflow model is not required. All walls are assumed isothermal and are set to mean values from Conjugate Heat Transfer (CHT) simulation 36 . Applying CHT would be the more robust and general approach but we assume the heat loss modeling to be good enough considering the other uncertainties.…”

Section: Boundary Conditionsmentioning

confidence: 99%

“…FIG. 6: Mean heat release rate for different simulations: current simulation with fixed temperature BC (T) vs. reference from Agostinelli et al 36 without CHT (R).…”

Section: Validation Of Lesmentioning

confidence: 99%

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LES-based prediction of technically premixed flame dynamics and comparison with perfectly premixed mode

et al. 2022

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The present study combines Large Eddy Simulation (LES) with System Identification (SI) to determine the Flame Transfer Functions (FTF) of technically premixed flames, which respond to fluctuations of upstream velocity as well as equivalence ratio. Two variants to obtain the corresponding FTFs from numerically determined time series data are reported and compared with experimental results. The experiment does not measure heat release rate directly, but instead CH* chemiluminescence. This is insufficient for FTF identification of technically premixed flames, but can be used for validation of the simulation. We implemented a CH* post-processor in the simulation and validate with experiment. After validation the simulation is used to identify the contributions of velocity and equivalence ratio to the FTF of technically premixed flame dynamics. We propose and compare two approaches for the identification of FTFs. The direct approach via Multiple Input Single Output system identification requires one simulation with simultaneous excitation of fuel and air inlets and carefully chosen input signals. The second approach reconstructs the FTF decomposition from two separate simulations, one perfectly premixed and one technically premixed, with reduced requirements on signal quality. We compare both approaches and discuss the FTFs of perfectly and technically premixed flames. Overall the LES/SI approach proved to be flexible and reliable for technically premixed flames.

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Section: Meshmentioning

confidence: 63%

Section: Boundary Conditionsmentioning

confidence: 99%

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LES-based prediction of technically premixed flame dynamics and comparison with perfectly premixed mode

et al. 2022

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“…Large-eddy simulation provides reliable predication of turbulent mixing and combustion for swirl burners [11,12]. However, for the purpose of optimization, prompt simulation of fuel mixing and burning in large-scale furnaces and gas turbine combustors at realistic flow rates still often relies on the use of Reynolds averaged Navier-Stokes (RANS) methods and requires experimental validation.…”

Section: Introductionmentioning

confidence: 99%

Testing Basic Gradient Turbulent Transport Models for Swirl Burners Using PIV and PLIF

Savitskii

Lobasov

Sharaborin

et al. 2021

Fluids

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The present paper reports on the combined stereoscopic particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) measurements of turbulent transport for model swirl burners without combustion. Two flow types were considered, namely the mixing of a free jet with surrounding air for different swirl rates of the jet (Re = 5 × 103) and the mixing of a pilot jet (Re = 2 × 104) with a high-swirl co-flow of a generic gas turbine burner (Re = 3 × 104). The measured spatial distributions of the turbulent Reynolds stresses and fluxes were compared with their predictions by gradient turbulent transport models. The local values of the turbulent viscosity and turbulent diffusivity coefficients were evaluated based on Boussinesq’s and gradient diffusion hypotheses. The studied flows with high swirl were characterized by a vortex core breakdown and intensive coherent flow fluctuations associated with large-scale vortex structures. Therefore, the contribution of the coherent flow fluctuations to the turbulent transport was evaluated based on proper orthogonal decomposition (POD). The turbulent viscosity and diffusion coefficients were also evaluated for the stochastic (residual) component of the velocity fluctuations. The high-swirl flows with vortex breakdown for the free jet and for the combustion chamber were characterized by intensive turbulent fluctuations, which contributed substantially to the local turbulent transport of mass and momentum. Moreover, the high-swirl flows were characterized by counter-gradient transport for one Reynolds shear stress component near the jet axis and in the outer region of the mixing layer.

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“…However, compared to models that compute chemistry explicitly (not necessarily refer to computing chemistry using resolved quantities known as no model or quasi-laminar chemistry, but also in thickened flame and partially stirred reactor models, where local temperature and pressure effects are inherently considered in reaction rate closure), tabulation models require additional non-trivial modelling treatment to account for heat loss effects, which were shown to have a strong impact on the FTF/FDF 12 . More recent studies by Kraus et al 17 and Agostinelli et al 18 employed advanced conjugated heat transfer method to account for the two-way coupling between the flame LES and burner walls. They showed that the heat loss effects are important for the swirl burners considered and need to be taken into account in the LES in order to correctly capture the thermoacoustic instability.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation and low-order modelling of azimuthal thermoacoustic instability in a gas turbine model annular combustor

Chen¹,

Swaminathan²,

Mazur³

et al. 2021

Preprint

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Self-excited spinning mode azimuthal instability in an annular combustor with non-swirling flow is investigated using large eddy simulation (LES). Compressible Navier-Stoke equations are solved with a flamelet combustion model to describe the subgrid chemistry−turbulence interactions. Two flamelet models, with and without heat loss effects, are compared to elucidate the non-adiabatic wall effects on the thermoacoustic instability. The azimuthal modes are captured well by both models with only marginal differences in the computed frequencies and amplitudes. By comparing with the experimental measurements, the frequencies given by the LES are approximately 10% higher and the amplitudes are well predicted. Further analysis of the experimental and LES data shows a similar dominant anti-clockwise spinning mode, under which a good agreement is observed for the phase-averaged heat release rate fluctuations. Dynamic mode decomposition (DMD) is applied to shed more light on this spinning mode. The LES and experimental DMD modes reconstructed for their azimuthal mode frequencies agree very well for the heat release fluctuations. The DMD mode structure for the acoustic pressure from the LES shows a considerable non-zero profile at the combustor outlet, which could be essential for azimuthal modes to establish in this annular combustor. Finally, a low-order modelling study was conducted using an acoustic network combined with the flame transfer function extracted from LES. The results show that the dominant mode is associated with the plenum showing a first longitudinal and azimuthal mixed mode structure. By tuning the plenum length to match the effective volume, the predicted frequency becomes very close to the measured value.

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Impact of wall heat transfer in Large Eddy Simulation of flame dynamics in a swirled combustion chamber

Cited by 29 publications

References 72 publications

LES-based prediction of technically premixed flame dynamics and comparison with perfectly premixed mode

LES-based prediction of technically premixed flame dynamics and comparison with perfectly premixed mode

Testing Basic Gradient Turbulent Transport Models for Swirl Burners Using PIV and PLIF

Large eddy simulation and low-order modelling of azimuthal thermoacoustic instability in a gas turbine model annular combustor

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