Challenging modeling strategies for LES of non-adiabatic turbulent stratified combustion

Fiorina, Benoît; Mercier, Renaud; Kuenne, G.; Ketelheun, Anja; Avdić, Amer; Janicka, J.; Geyer, D.; Dreizler, Andreas; Alenius, Emma; Duwig, Christophe; Trisjono, Philipp; Kleinheinz, Konstantin; Kang, Seongwon; Pitsch, Heinz; Proch, Fabian; Marincola, F. Cavallo; Kempf, Andreas

doi:10.1016/j.combustflame.2015.07.036

Cited by 82 publications

(45 citation statements)

References 44 publications

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“…Verification of these numerics is provided elsewhere [41][42][43][44]. Finally, note that OpenFOAM solvers or earlier versions have been observed to reproduce satisfactory results in a large variety of combustion problems [19,39,[45][46][47][48][49][50][51].…”

Section: Methodsmentioning

confidence: 99%

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Numerical Simulations of Combustion Instabilities in a Combustor with an Augmentor-Like Geometry

Gonzalez-Juez

2019

Aerospace

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With the goal of assessing the capability of Computational Fluid Dynamics (CFD) to simulate combustion instabilities, the present work considers a premixed, bluff-body-stabilized combustor with well-defined inlet and outlet boundary conditions. The present simulations produce flow behaviors in good qualitative agreement with experimental observations. Notably, the flame flapping and standing acoustic waves seen in the experiments are reproduced by the simulations. Moreover, present predictions for the dominant instability frequency have an error of 7% and those of the rmspressure fluctuations show an error of 16%. In addition, an analysis of simulation results for the limit cycle complements previous experimental analyses by supporting the presence of an active frequency-locking mechanism.

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Section: Methodsmentioning

confidence: 99%

“…The outlet is open to the atmosphere and it is modeled using a sponge method [49]. With this 106 method, the computational domain includes the geometry shown in Fig.…”

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confidence: 99%

Numerical Simulations of Combustion Instabilities in a Combustor with an Augmentor-Like Geometry

Gonzalez-Juez

2019

Aerospace

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“…Subgrid scale models are required to capture key quantities, such as the flame thickness or the flame wrinkling, which are not fully resolved on practical meshes [17,18]. As recently illustrated in a collaborative study performed in the framework of the TNF workshop [19], LES turbulent combustion models designed for turbulent premixed combustion yield good predictions of the mean statistical flame properties such as the flame front position, the temperature field, or the species mass fractions.…”

Section: To Cite This Versionmentioning

confidence: 99%

Experimental and Numerical Investigation of the Response of a Swirled Flame to Flow Modulations in a Non-Adiabatic Combustor

Chatelier

Guiberti

Mercier

et al. 2019

Flow Turbulence Combust

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et al.. Experimental and numerical investigation of the response of a swirled flame to flow modulations in a non-adiabatic combustor.Abstract Turbulent combustion models for Large Eddy Simulation (LES) aims at predicting the flame dynamics. So far, they have been proven to predict correctly the mean flow and flame properties in a wide range of configurations. A way to challenge these models in unsteady situations is to test their ability to recover turbulent flames submitted to harmonic flow modulations. In this study, the Flame Transfer Function (FTF) of a CH 4 /H 2 /air premixed swirled-stabilized flame submitted to harmonic flowrate modulations in a non-adiabatic combustor is compared to the response computed using the Filtered TAbulated Chemistry for LES (F-TACLES) formalism. Phase averaged analysis of the perturbed flow field and flame response reveal that the velocity field determined with Particle Image Velocimetry measurements, the heat release distribution inferred from OH* images and the probability of presence of burnt gases deduced from OH-Planar Laser Induced Fluorescence measurements are qualitatively well reproduced by the simulations. However, noticeable differences between experiments and simulations are also observed in a narrow frequency range. A detailed close-up view of the flow field highlight differences in experimental OH* and numerical volumetric heat release rate distributions which are at the origin of the differences observed between the numerical and experimental FTF. These differences mainly originate from the outer shear layer of the swirling jet where a residual reaction layer takes place in the simulations which is absent in the experiments. Consequences for turbulent combustion modeling are suggested by examining the evolution of the perturbed flame brush envelope along the downstream distance of the perturbed flames. It is shown that changing the grid resolution and the flame subgrid scale wrinkling factor in these regions does not alter the numerical results. It is finally concluded that the combined effects of strain rate and enthalpy defect due to heat losses are the main factors leading to small but sizable differences of the flame response to coherent structures synchronized by the acoustic forcing in the outer shear layer of the swirling flow. These small differences in flame response lead in turn to a misprediction of the FTF at specific forcing frequencies.

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“…The Darmstadt Turbulent Stratified Burner employed here is complementary to the Cambridge/Sandia configuration and has been widely used as a test case for model development [7]. A series of lean turbulent stratified flames (TSF) stabilized by an inner pilot flame are produced [8] which have been the subject of experimental as well as numerical work [2,7,8].…”

Section: Introductionmentioning

confidence: 99%

Multiple conditioned analysis of the turbulent stratified flame A

Stahler

Geyer

Magnotti

et al. 2017

Proceedings of the Combustion Institute

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To explore the effect of stratification on lean premixed combustion in a turbulent flow, an experimental investigation on the TSFA flame of the Darmstadt stratified burner is conducted. Spatially highly resolved major species concentrations and temperature are measured by 1D Raman-Rayleigh. Temperature gradients from line data are corrected to the flame front normal by the means of Crossed Planar Rayleigh Imaging. A conditioning based on multiple criteria relevant for stratified combustion is applied to the large dataset and allows to analyze the impact of stratification on the flame structure. Conditioning criteria are the local equivalence ratio =0.75), the local thermal progress variable =0.54), the stratification level (instantaneous flame-normal gradient in equivalence ratio), and a temperature difference over the 1D probe volume, ensuring the flame front is included. Conditionally averaged quantities such as temperature profiles in the flame-normal coordinate system, equivalence ratio, H 2 mass fractions, and temperature gradients are parameterized on the local equivalence ratio gradient in order to understand the impact of stratification on the flame structure. The temperature profiles in this back-supported configuration are more affected on the reactant side than on the product side by stratification. In contrast to that, equivalence ratios as well as mass fractions of hydrogen are found to be sensitive to stratification on the product side as well as in the reactants. Profiles are altered even in the reaction zone by enhancing the equivalence ratio gradients, which is in contrast to results obtained in the Cambridge/Sandia configuration. This finding indicates the influence of turbulence on stratified combustion in the thin-reaction-zone regime, as characterized for instance by the difference in Karlowitz and Damköhler numbers for the Darmstadt versus the Cambridge/Sandia configuration.

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Challenging modeling strategies for LES of non-adiabatic turbulent stratified combustion

Abstract: Five different low-Mach large eddy simulations are compared to the turbulent stratified flame experiments conducted at the Technical University of Darmstadt (TUD). The simulations were contributed by TUD,

Cited by 82 publications

References 44 publications

Numerical Simulations of Combustion Instabilities in a Combustor with an Augmentor-Like Geometry

Numerical Simulations of Combustion Instabilities in a Combustor with an Augmentor-Like Geometry

Experimental and Numerical Investigation of the Response of a Swirled Flame to Flow Modulations in a Non-Adiabatic Combustor

Multiple conditioned analysis of the turbulent stratified flame A

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