LES Study of Transverse Acoustic Instabilities in a Swirled Kerosene/Air Combustion Chamber

Ghani, Abdulla; Poinsot, Thiérry; Gicquel, Laurent; Müller, Jens-Dominik

doi:10.1007/s10494-015-9654-9

Cited by 36 publications

(16 citation statements)

References 62 publications

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“…DMD was first applied to non-reacting jets where it identified the spatial structure and frequency of the jet's vortex shedding [26,27]. DMD has since been extended to the analysis of numerous experimental and numerical efforts in understanding the coupling between hydrodynamics and the resulting thermoacoustics [28][29][30][31][32][33]. Variants of DMD have been proposed to tackle specific problems such as resolving transient and quasi-periodic dynamics [34].…”

Section: Deconvolution Of Flow Dynamicsmentioning

confidence: 99%

Coupled interactions of a helical precessing vortex core and the central recirculation bubble in a swirl flame at elevated power density

Zhang

Boxx

Meier

et al. 2019

Combustion and Flame

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The PRECCINSTA GTMC was studied at elevated pressure and power density with 6 kHz stereoscopic particle image velocimetry (SPIV), OH* chemiluminescence (CL), and 100 kHz dynamic pressure measurements. This technically premixed, swirl stabilized flame exhibited self-excited thermoacoustic oscillations with limit-cycle behavior. A helical precessing vortex core (PVC) was detected within the inner shear layer, between the central recirculation bubble (CRB) and the reactant jets. The PVC was found to be the delineating flow feature for combustion dynamics even at elevated pressure. Sparse dynamic mode decomposition (DMD) of the velocity fields deconvolved the dynamics into a thermoacoustic and PVC mode. The precession of the PVC was at a non-harmonic frequency to the thermoacoustic oscillations, and at least twice that of findings at atmospheric conditions. Nevertheless, the continuous and persistent structure of the PVC allows it promote unsteady heat release to sustain the thermoacoustic cycle. The three dimensional structure of the reactant jets, central recirculation bubble, and PVC was reconstructed by double phase conditioning the reconstructed velocity field. The surface of the CRB was observed to transition between asymmetric and symmetric states depending on the thermoacoustic phase. Analysis of the swirling strength values on the CRB surface indicates the interaction strength between the hydrodynamic structures of the PVC and CRB. When this coupling is large, the heat release determined by the mean OH*-CL intensity is maximum. These findings indicate a critical role of the PVC and CRB interaction on combustion in unstable swirl flames at conditions closer to those found in a modern gas turbine engine.

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Section: Deconvolution Of Flow Dynamicsmentioning

confidence: 99%

Coupled interactions of a helical precessing vortex core and the central recirculation bubble in a swirl flame at elevated power density

Zhang

Boxx

Meier

et al. 2019

Combustion and Flame

View full text Add to dashboard Cite

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“…Their thermoacoustic dynamics has been investigated in countless studies, e.g. [5,7,26,9,16]. Recently, an increasing number of studies dealing with the combustion process taking place in the second stage have been published.…”

Section: Introductionmentioning

confidence: 99%

Autoignition flame dynamics in sequential combustors

Schulz

Noiray

2018

Combustion and Flame

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This numerical study deals with the heat release rate response of a sequential combustor flame to temperature perturbations. These flames are found in the new generation of gas turbine combustors, which are based on sequential combustion technologies. It is shown that the temperature perturbations T upstream of the fuel injection induce mixture fraction oscillations Z which also propagate toward the reaction zone, and that the combination of these two perturbations yields a strongly nonlinear heat release rate response Q . Large Eddy Simulation (LES) were performed using an Analytically Reduced Chemistry (ARC) mechanism, which includes 22 transported species in combination with the Dynamic Thickened Flame model (DTF). The burner flame transfer function (BFTF) giving the flame response with respect to T is obtained using a broadbandexcitation-based system identification (SI) as well as harmonic single frequency excitations. A simplified configuration with perfectly premixed conditions is considered to quantify the respective contributions of the different types of perturbation. These simulations highlight (i) the strong nonlinearity of the flame response to temperature perturbations, and (ii) the difficulty to break down the global flame response into independent driving mechanisms by making use of "simplified" configurations.

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“…Among all helical, shear later disturbances of swirled ows, the most well known is the PVC (precessing vortex core) and it plays a role in many CIs. Experiments [15,[151][152][153] as well as LES [12,14,154,155] showed that PVCs can trigger certain CI modes, disappear when the ame is ignited or appear only for certain ame positions. PVCs can even appear intermittently during CI.…”

Section: Global Stability Of Swirling Owsmentioning

confidence: 99%

Prediction and control of combustion instabilities in real engines

Poinsot

2017

Proceedings of the Combustion Institute

551

216

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This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID: 17713Open Archive Toulouse Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. To cite this version: AbstractThis paper presents recent progress in the eld of thermoacoustic combustion instabilities in propulsion engines such as rockets or gas turbines. Combustion instabilities have been studied for more than a century in simple laminar con gurations as well as in laboratory-scale turbulent ames. These instabilities are also encountered in real engines but new mechanisms appear in these systems because of obvious differences with academic burners: larger Reynolds numbers, higher pressures and power densities, multiple inlet systems, complex fuels. Other differences are more subtle: real engines often feature speci c unstable modes such as azimuthal instabilities in gas turbines or transverse modes in rocket chambers. Hydrodynamic instability modes can also differ as well as the combustion regimes, which can require very different simulation models. The integration of chambers in real engines implies that compressor and turbine impedances control instabilities directly so that the determination of the impedances of turbomachinery elements becomes a key issue. Gathering experimental data on combustion instabilities is dif cult in real engines and large Eddy simulation (LES) has become a major tool in this eld. Recent examples, however, show that LES is not suf cient and that theory, even in these complex systems, plays a major role to understand both experimental and LES results and to identify mitigation techniques.

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LES Study of Transverse Acoustic Instabilities in a Swirled Kerosene/Air Combustion Chamber

Cited by 36 publications

References 62 publications

Coupled interactions of a helical precessing vortex core and the central recirculation bubble in a swirl flame at elevated power density

Coupled interactions of a helical precessing vortex core and the central recirculation bubble in a swirl flame at elevated power density

Autoignition flame dynamics in sequential combustors

Prediction and control of combustion instabilities in real engines

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