Reconstruction subgrid models for nonpremixed combustion

Mellado, Juan Pedro; Sarkar, Sutanu; Pantano, Carlos

doi:10.1063/1.1608008

Cited by 34 publications

(26 citation statements)

References 46 publications

(64 reference statements)

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“…More recently, a new class of reconstruction subgrid-scale models has been proposed that combine the purely mathematical approximate deconvolution procedure with physical information from an assumed scalar spectrum to match specific scalar moments [73,74]. Approximate reconstruction using moments provides an alternative approach that avoids the intermediate step of modeling the joint-PDF associated with subgrid-scale fluctuations.…”

Section: Large Eddy Simulationsmentioning

confidence: 99%

Understanding and predicting soot generation in turbulent non-premixed jet flames.

Wang

Kook²,

Doom³

et al. 2010

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This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a strong impact on the rate of soot nucleation and particle coagulation, but little sensitivity in the overall trends was found with different fuels. An extensive array of non-intrusive optical and laser-based measurements was performed in turbulent non-premixed jet flames established on specially designed piloted burners. Soot concentration data was collected throughout the flames, together with instantaneous images showing the relationship between soot and the OH radical and soot and PAH. A detailed chemical kinetic mechanism for ethylene combustion, including fuel-rich chemistry and benzene formation steps, was compiled, validated, and reduced. The reduced ethylene mechanism was incorporated into a high-fidelity LES code, together with a momentbased soot model and models for thermal radiation, to evaluate the ability of the chemistry and soot models to predict soot formation in the jet diffusion flame. The LES results highlight the importance of including an optically-thick radiation model to accurately predict gas temperatures and thus soot formation rates. When including such a radiation model, the LES model predicts mean soot concentrations within 30% in the ethylene jet flame. 3This page left intentionally blank.

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Section: Large Eddy Simulationsmentioning

confidence: 99%

Understanding and predicting soot generation in turbulent non-premixed jet flames.

Wang

Kook²,

Doom³

et al. 2010

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“…5,7-9,13-15 A more limited number of studies have also included a posteriori tests using LES. 9,15 These studies note modeling error in the filtered scalar evolution as a factor in variance prediction, but do not specifically characterize its effects and also do not account for numerical error in the filtered scalar evolution.…”

Section: Background and Motivationmentioning

confidence: 99%

A posteriori analysis of numerical errors in subfilter scalar variance modeling for large eddy simulation

Kaul

Raman

2011

Physics of Fluids

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“…As stated above, the first moment of the local (SGS) PDF is always computable from LES, so that the focus is on computing the second moment, i.e., the SGS scalar variance. An extensive literature exists on the topic of the SGS scalar variance computation 2,4,5,7,16,17 but not for supercritical turbulent flows for which, as seen in Sec. II, the variance equation is considerably more complex than in the already studied flows, indicating possible departures from previous findings, as implied by previous results.…”

Section: The Pdf Of the Conserved Scalarmentioning

confidence: 99%

“…30 Furthermore, the deconvolution relies on the form of the convolution-filter kernel and on the shape of the spectrum of the field. 17 The series' rate of convergence is situation dependent. For example, it has been found 31 that N ¼ 3 is sufficient to bring an improvement in that for a quantity /, / Ã À / À Á is not null showing that the expansion is indeed effective, and for N !…”

Section: A the Approximate Deconvolution Modelmentioning

confidence: 99%

“…Fluids 23, 085101 (2011) secondary filtering through the use of a relaxation parameter in the Navier-Stokes (NS) equations. To mitigate both these issues, Pantano and Sarkar 16 and Mellado et al 17 proposed an approximate reconstruction using moments (ARM) method which, based on the definition of an intermediate field, leads to computing the SGS scalar variance by imposing equality between the real moment and that of the intermediate field. This procedure results in an expression for a parameter c 0 , characterizing the model, that is obtained by finding the real and positive solution of a second-order polynomial equation.…”

Section: -5mentioning

confidence: 99%

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The subgrid-scale scalar variance under supercritical pressure conditions

Masi

Bellan

2011

Physics of Fluids

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To model the subgrid-scale (SGS) scalar variance under supercritical-pressure conditions, an equation is first derived for it. This equation is considerably more complex than its equivalent for atmospheric-pressure conditions. Using a previously created direct numerical simulation (DNS) database of transitional states obtained for binary-species systems in the context of temporal mixing layers, the activity of terms in this equation is evaluated, and it is found that some of these new terms have magnitude comparable to that of governing terms in the classical equation. Most prominent among these new terms are those expressing the variation of diffusivity with thermodynamic variables and Soret terms having dissipative effects. Since models are not available for these new terms that would enable solving the SGS scalar variance equation, the adopted strategy is to directly model the SGS scalar variance. Two models are investigated for this quantity, both developed in the context of compressible flows. The first one is based on an approximate deconvolution approach and the second one is a gradient-like model which relies on a dynamic procedure using the Leonard term expansion. Both models are successful in reproducing the SGS scalar variance extracted from the filtered DNS database, and moreover, when used in the framework of a probability density function (PDF) approach in conjunction with the b-PDF, they excellently reproduce a filtered quantity which is a function of the scalar. For the dynamic model, the proportionality coefficient spans a small range of values through the layer cross-stream coordinate, boding well for the stability of large eddy simulations using this model.

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Reconstruction subgrid models for nonpremixed combustion

Cited by 34 publications

References 46 publications

Understanding and predicting soot generation in turbulent non-premixed jet flames.

Understanding and predicting soot generation in turbulent non-premixed jet flames.

A posteriori analysis of numerical errors in subfilter scalar variance modeling for large eddy simulation

The subgrid-scale scalar variance under supercritical pressure conditions

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