A DNS evaluation of mixing models for transported PDF modelling of turbulent nonpremixed flames

Krisman, Alex; Tang, Joshua; Hawkes, Evatt R.; Lignell, David O.; Chen, Jacqueline H.

doi:10.1016/j.combustflame.2014.01.009

Cited by 37 publications

(26 citation statements)

References 46 publications

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“…Similar trade-offs are noted in studies of other flames, for example Refs. [27,28] who studied these three mixing models on a piloted jet diffusion flame and a turbulent nonpremixed bluff body flames, respectively, and recent work comparing DNS and TPDF models [100].…”

Section: Discussionmentioning

confidence: 99%

Modelling n-dodecane spray and combustion with the transported probability density function method

Pei

Hawkes

Kook

et al. 2015

Combustion and Flame

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118

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An n-dodecane spray in temperature and pressure conditions typical of diesel engines, known as Spray A, is modelled by the transported probability density function (TPDF) method coupled with a time-dependent Reynoldsaveraged k − turbulence model and a Lagrangian discrete phase model of the liquid spray. To establish a baseline for comparisons, non-reacting cases are first studied. Good results are obtained for the vapour penetration, the mean and variance of fuel mixture fraction, and velocity profiles, with variations in ambient density and injection pressure. These comparisons are more extensive than previous studies due to new experimental data being available. Reacting cases are then investigated for a number of ambient * Corresponding author, Phone number: +1 (630) 252-5237, Present address:conditions and injection parameters, employing a reduced chemical kinetic model. The chemical mechanism incorporates an OH* sub-mechanism (Hall and Petersen, Int. J. Chem. Kinet. 38, 2006, pp. 714-724) which enables a direct comparison with experimental measurements of the lift-off length that are based on OH* chemiluminescence. To assess the importance of interactions between turbulence and chemistry, the results from the PDF model are compared to the measurements and to those from a well-mixed model that ignores turbulent fluctuations. Variations of ambient temperature, ambient oxygen concentration, ambient density, and injection pressure are considered. In all cases the PDF model with the EMST mixing model and C φ = 1.5 shows an excellent agreement with the experimental lift-off length and presents improved results compared with the well-mixed model.Ignition delay is however over-predicted by both the PDF method and wellmixed models. Available shock tube data suggests that this may be due to the chemical kinetic model over-predicting ignition delay at higher pressures.

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Section: Discussionmentioning

confidence: 99%

Modelling n-dodecane spray and combustion with the transported probability density function method

Pei

Hawkes

Kook

et al. 2015

Combustion and Flame

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118

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“…The mapping is statistical in that the reference variables and the quantities to which they are mapped describe the same statistical distribution but they are stochastically independent [11]. This indirect localness is essential otherwise the model would violate the mixing model linearity and independence principles [9] leading to deficiencies such as stranding and an underprediction of conditional variances [12].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

A stochastic multiple mapping conditioning computational model in OpenFOAM for turbulent combustion

et al. 2018

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Highlights• Stochastic MMC-LES and MMC-RANS are implemented into OpenFOAM.• Code architecture is based on layered template classes and abstract submodels.• Mass consistency of the hybrid Eulerian and Lagrangian schemes is demonstrated.• Numerical convergence with increasing stochastic particles is demonstrated.• Numerical convergence with increasing aerosol species sections is demonstrated. AbstractComputational models for combustion must account for complex and inherently interconnected physical processes including dispersion, mixing, chemical reactions, particulate nucleation and growth and, critically, the interactions of these with turbulence. The development of affordable and accurate models that are widely applicable is a work in progress. Stochastic multiple mapping conditioning (MMC) is a fast-emerging approach that has been successfully applied to non-premixed, premixed and partially premixed flames as well to the modelling of liquid and solid particulate synthesis. The method solves the conventional PDF transport equation but incorporates an additional constraint in that the mixing is localised in a reference space. This paper describes the numerical implementation of stochastic MMC in an OpenFOAM compatible code called mmcFoam. The model concepts and equations along with alternative submodels, code structure and numerical schemes are explained. A focus is placed on validation of the computational methods in particular demonstrating numerical convergence and mass consistency of the hybrid Eulerian/Lagrangian A C C E P T E D M A N U S C R I P T schemes. Four validation cases are selected including a combustion direct numerical simulation (DNS) case, two combustion experimental jet flame cases and a non-combusting particulate synthesis case. The results show that the total mass and mass distribution of Eulerian and Lagrangian schemes are consistent and confirm that the solutions numerically converge with increasing number of stochastic computational particles and sections for describing particulate size distribution.

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“…86 In addition, despite its more physically justifiable modeling, the EMST does not always out perform the IEM and other models. For example, Krisman et al 98 found in a comparison of mixing models for LES-FDF of several large DNS flames that only the EMST correctly predicted reignition at high Damkohler numbers. However, at low Damkohler numbers, the EMST over predicts reignition while the IEM and MC under predict it.…”

Section: Les-fdfmentioning

confidence: 96%

Survey of Turbulent Combustion Models for Large-Eddy Simulations of Propulsive Flowfields

Foster

Miller

2015

53rd AIAA Aerospace Sciences Meeting

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A general review of turbulent combustion modeling closures applicable to large eddy simulations (LES) is provided. The focus is on "regime-independent" models able to provide turbulent combustion closures ranging from purely premixed to purely non-premixed and all regimes between these two limits. Special emphasis is placed on primary propulsion applications, including liquid rocket engines, diesel engines, gas turbines, and scramjets. These applications span a large range of physical phenomena including both ideal-and real-gas behavior, single-phase and multi-phase combustion, relatively low Mach number to supersonic and hypersonic combustion, and relatively simple geometries to highly complex geometries. Three classes of models are identified as possibly providing such broad based modeling closures: flamelet-library/presumed probability density function (PDF) models, linear eddy based models (LEM), and transported PDF or filtered density function (FDF) based models. This review focuses both on fundamental physical assumptions that apply across all of the models and assumptions that apply to each of the models individually. Namely, assumptions regarding the presumed size of the large dimensional turbulent scalar manifold apply to all of the models; however, flamelet models almost always presume only a few dimensions are necessary to yield adequate representation of the larger, turbulent manifold. In contrast, LEM and FDF models are not, in theory, bound by any manifold size assumptions (i.e. direct calculation of the turbulent scalar manifold is possible); however, due to current computational limitations, these models often employ manifold reduction techniques which are usually not as restrictive as those used by flamelet models. Individual assumptions associated with the specific formulation of each model are also analyzed. From these discussions, additional novel results testing some of the fundamental physical assumptions associated with each model are provided from a unique database of DNS of high pressure turbulent reacting temporally developing shear flames. The DNS database includes simulations of H2/O2, H2/Air, and Kerosene/Air flames with both detailed and reduced chemistry. The DNS include real property models, a real-gas equation of state, and generalized heat and mass diffusion derived from non-equilibrium thermodynamics. The simulations span a large range of Reynolds numbers and pressures (up to 125 atm), with resolutions approaching 1 billion grid points. Finally, some general comments towards the future challenges related to LES combustion modeling are offered. NomenclatureA m , B m = mixture parameters for the equation of state C Ω = modeling constant dW = differential increment of the Wiener process D = molecular diffusivitytotal energy (internal plus kinetic) E = modeling term F L = filtered mass density function F stir = triplet mapping advection model G = filter kernel H ,α = partial molar enthalpy of species α J i,α = mass flux vector of species α k sgs = subgrid turbulence kinetic energy M...

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A DNS evaluation of mixing models for transported PDF modelling of turbulent nonpremixed flames

Cited by 37 publications

References 46 publications

Modelling n-dodecane spray and combustion with the transported probability density function method

Modelling n-dodecane spray and combustion with the transported probability density function method

A stochastic multiple mapping conditioning computational model in OpenFOAM for turbulent combustion

Survey of Turbulent Combustion Models for Large-Eddy Simulations of Propulsive Flowfields

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