LES combustion modeling for high Re flames using a multi-phase analogy

Sabelnikov, Vladimir; Fureby, Christer

doi:10.1016/j.combustflame.2012.09.008

Cited by 101 publications

(55 citation statements)

References 51 publications

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“…The default model of τ m in OpenFOAM uses the effective viscosity (μ e f f = μ + μ t ) and the dissipation rate, which has been used in previous studies of turbulent flames [50,79]. The present study applies a recently developed mixing time model which is used in the extended LES-PaSR model for high Reynolds, moderate Damköhler number turbulent flames [80,81]. The modelling is based on the subgrid velocity stretch time and Kolmogorov time scales, in the form of [80,81]:…”

Section: Numerical Methods For Flame Simulationsmentioning

confidence: 97%

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Prediction of combustion instability limit cycle oscillations by combining flame describing function simulations with a thermoacoustic network model

Han

Morgans

2015

Combustion and Flame

202

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a b s t r a c t Accurate prediction of limit cycle oscillations resulting from combustion instability has been a long-standing challenge. The present work uses a coupled approach to predict the limit cycle characteristics of a combustor, developed at Cambridge University, for which experimental data are available (Balachandran, Ph.D. thesis, 2005). The combustor flame is bluff-body stabilised, turbulent and partially-premixed. The coupled approach combines Large Eddy Simulation (LES) in order to characterise the weakly non-linear response of the flame to acoustic perturbations (the Flame Describing Function (FDF)), with a low order thermoacoustic network model for capturing the acoustic wave behaviour. The LES utilises the open source Computational Fluid Dynamics (CFD) toolbox, OpenFOAM, with a low Mach number approximation for the flow-field and combustion modelled using the PaSR (Partially Stirred Reactor) model with a global one-step chemical reaction mechanism for ethylene/air. LES has not previously been applied to this partially-premixed flame, to our knowledge. Code validation against experimental data for unreacting and partially-premixed reacting flows without and with inlet velocity perturbations confirmed that both the qualitative flame dynamics and the quantitative response of the heat release rate were captured with very reasonable accuracy. The LES was then used to obtain the full FDF at conditions corresponding to combustion instability, using harmonic velocity forcing across six frequencies and four forcing amplitudes. The low order thermoacoustic network modelling tool used was the open source OSCILOS (http://www.oscilos.com). Validation of its use for limit cycle prediction was performed for a well-documented experimental configuration, for which both experimental FDF data and limit cycle data were available. The FDF data from the LES for the present test case was then imported into the OSCILOS geometry network and limit cycle oscillations of frequency 342 Hz and normalised velocity amplitude of 0.26 were predicted. These were in good agreement with the experimental values of 348 Hz and 0.21 respectively. This work thus confirms that a coupled numerical prediction of limit cycle behaviour is possible using an entirely open source numerical framework.

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Section: Numerical Methods For Flame Simulationsmentioning

confidence: 97%

“…The present study applies a recently developed mixing time model which is used in the extended LES-PaSR model for high Reynolds, moderate Damköhler number turbulent flames [80,81]. The modelling is based on the subgrid velocity stretch time and Kolmogorov time scales, in the form of [80,81]:…”

Section: Numerical Methods For Flame Simulationsmentioning

confidence: 99%

Prediction of combustion instability limit cycle oscillations by combining flame describing function simulations with a thermoacoustic network model

Han

Morgans

2015

Combustion and Flame

202

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“…It should be noticed that the parameters of GLB3 from [51] were adjusted to those shown in Table 1. The original parameters gave very low values of O2 in our calculations and correspondingly large values of NO.…”

Section: Kinetics Schemesmentioning

confidence: 99%

“…-the global three-step mechanism (hereafter GLB3) constructed in the spirit of Sabelnikov and Fureby [51]:…”

Section: Kinetics Schemesmentioning

confidence: 99%

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Reynolds-Averaged, Scale-Adaptive and Large-Eddy Simulations of Premixed Bluff-Body Combustion Using the Eddy Dissipation Concept

Lysenko¹,

Ertesvåg

2017

Flow Turbulence Combust

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A lean premixed propane/air bluff-body stabilized flame (Volvo test rig) is calculated using the Scale-Adaptive Simulation turbulence model (SAS) and Large-Eddy simulations (LES) as well as the conventional Reynoldsaveraged approach (RAS). RAS and SAS are closed by the standard k-ǫ and the k-ω Shear Stress Transport (SST) turbulence models, respectively. The conventional Smagorinsky and the k-equation sub-grid scales models are used for the LES closure. Effects of the sub-grid scalar flux modeling using the classical gradient hypothesis and Clark's tensor diffusivity closures both for the inert and reactive LES flows are discussed. The Eddy Dissipation Concept (EDC) is used for the turbulence-chemistry interaction. It assumes that molecular mixing and the subsequent combustion occur in the 'fine structures' (smaller dissipative eddies, which are close to the Kolmogorov scales). Assuming the full turbulence energy cascade, the characteristic length and velocity scales of the 'fine structures' are evaluated using different turbulence models (RAS, SAS and LES). The finite-rate chemical kinetics is taken into account by treating the 'fine structures' as constant pressure and adiabatic homogeneous reactors, calculated as a system of ordinary-differential equations (ODEs) described by a Perfectly Stirred Reactor (PSR) concept. Several further enhancements to model the PSRs are proposed, including a new Livermore Solver (LSODA) for integrating stiff ODEs and a new correction to calculate the PSR time scales. All models have been implemented as a stand-alone application edcPisoFoam based on the OpenFOAM technology. Additionally, several RAS calculations were performed using the Turbulence Flame Speed Closure model in Ansys Fluent to assess effects of the heat losses by modeling the conjugate heat transfer between the bluff-body and the reactive flow. Effects of the turbulence Schmidt number on RAS results are discussed as well. Numerical results are compared with available experimental data. Reasonable consistency between experimental data and numerical results provided by RAS, SAS and LES is observed. In general, there is satisfactory agreement between present LES-EDC simulations, numerical results by other authors and measurements without any major modification to the EDC closure constants, which gives a quite reasonable indication on the adequacy and accuracy of the method and its further application for turbulent premixed combustion simulations.

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Challenges for Large Eddy Simulation of Engineering Flows

Fureby

2016

Whither Turbulence and Big Data in the 21st Century?

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LES combustion modeling for high Re flames using a multi-phase analogy

Cited by 101 publications

References 51 publications

Prediction of combustion instability limit cycle oscillations by combining flame describing function simulations with a thermoacoustic network model

Prediction of combustion instability limit cycle oscillations by combining flame describing function simulations with a thermoacoustic network model

Reynolds-Averaged, Scale-Adaptive and Large-Eddy Simulations of Premixed Bluff-Body Combustion Using the Eddy Dissipation Concept

Challenges for Large Eddy Simulation of Engineering Flows

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