Soot Modeling in a Turbulent Unconfined C2H4/Air Jet Flame

Blacha, Thomas; Domenico, Massimiliano Di; Köhler, Markus; Gerlinger, Peter; Aigner, Manfred

doi:10.2514/6.2011-114

Cited by 9 publications

(16 citation statements)

References 18 publications

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“…The averaging in temperature space is also applied for the OTA heat radiation model in direct analogy to the averaging of the chemical source term. The equations for the heat sink have been derived from the work of Mauß [45] and can be found in detail in Blacha et al [46].…”

Section: Numerical Modelmentioning

confidence: 99%

Experimental characterization and numerical simulation of a sooting lifted turbulent jet diffusion flame

Köhler

Geigle

Blacha

et al. 2012

Combustion and Flame

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A sooting C 2 H 4 /air jet diffusion flame was investigated experimentally by laser measuring techniques and the results are compared to CFD calculations. The target flame (C 2 H 4 10.4 g/min, bulk exit velocity 44 m/s, RE = 10000) exhibits well-defined boundary conditions and presents a good test case for model validation. Flow velocity, temperature and soot volume fraction in this flame has been measured previously. In this paper, further experimental results from Raman scattering and laser-induced fluorescence (LIF) measurements are presented to expand the validation data base. Raman scattering is used to measure the fuel/air mixing prior to combustion, while LIF of PAHs monitors the soot precursor region and successive planar OH-LIF serves to map the flame front position and its statistics. Furthermore, a numerical simulation of this flame was performed based on the DLR in-house code THETA. Within the scope of the test case presented here, the code combines a relatively detailed description of the gas phase kinetics coupled with a detailed yet computation-efficient soot model, suitable for CFD applications. This model has been designed to predict soot for a variety of fuels and flames with good accuracy at relatively low computational costs. Universal model parameters are applied, which requires no tuning for the dependence of test case or fuel. The experimental and numerical results are compared and discussed with special emphasis on the pre-flame region of the jet and up to the downstream position where significant soot concentrations are present. Validation shows the general applicability of the CFD code with implemented soot model to rather complex systems like the target sooting turbulent jet flame. Identified discrepancies are analyzed and can be explained, while opening up the field for future optimization of parts of the CFD code.

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Section: Numerical Modelmentioning

confidence: 99%

Experimental characterization and numerical simulation of a sooting lifted turbulent jet diffusion flame

Köhler

Geigle

Blacha

et al. 2012

Combustion and Flame

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“…Comprehensive validation data, including measurements of temperature, concentrations of ethylene and polycyclic aromatic hydrocarbons (PAHs) as well as simultaneous measurements of the velocity field and the soot volume fraction are available for the chosen test case. 13,14,15 Previous Reynolds averaged Navier-Stokes simulations (RANS) of this flame 13,16 showed a reasonable overall agreement between simulation and experiment. 13 These simulations however revealed the limitations of RANS to accurately predict turbulent mixing phenomena as deviations between predicted and measured soot volume fractions could partially be attributed to inaccurate predictions of turbulent mixing.…”

Section: Introductionmentioning

confidence: 64%

“…The LES approach provides a rigorous treatment of turbulent mixing phenomena by resolving turbulent scales. Another discrepancy between simulation and experiment was that the previously published RANS simulation 13,16 predicted an too early onset of soot formation. Furthermore, soot was oxidized too fast.…”

Section: Introductionmentioning

confidence: 95%

Large Eddy Simulations of a Sooting Lifted Turbulent Jet-Flame

Eberle

Gerlinger

Aigner

2017

55th AIAA Aerospace Sciences Meeting

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A sooting, turbulent jet flame is investigated numerically by large eddy simulations (LES). The ethylene fueled flame has been characterized experimentally by various nonintrusive high-speed laser diagnostic techniques yielding comprehensive validation data. Combustion is described by finite-rate chemistry with an assumed probability density function (APDF) closure for sub grid scale chemistry-turbulence interaction. The evolution of polycyclic aromatic hydrocarbons (PAHs) is modeled using a recently published sectional model which considers PAH radicals and reversible PAH chemistry. A novel sectional soot model is presented and investigated. This model provides detailed information about the soot morphology by taking into account the evolution of fractal soot aggregates. The model has been validated for laminar diffusion flames where excellent agreement to measurements has been observed. This validated model has then be used for LES of a turbulent jet flame and a very good agreement to measured velocity components, ethylene mole fractions, and soot volume fractions has been found.

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“…[22][23][24][25][26] A stiff-chemistry solver is used to solve the reduced chemical mechanism for Jet-A1 combustion with 59 species and 372 elementary reactions from Slavinskaya et al [27][28][29] This mechansim has already been validated extensively by various authors. [29][30][31][32] The vaporized jet fuel is represented by four surrogate species, namely N-dodecane nC 12 H 26 , iso-octane C 8 H 18 , cyclo-hexane C 6 H12 and toluene C 7 H 8 . These represent the most important chemical classes n-alkanes, iso-alkanes, cyclo-alkanes and aromatics, respectively.…”

Section: B Turbulent Combustion Modelingmentioning

confidence: 99%

Large-Eddy Simulation of Spray Flames in the DLR Generic Single Sector Combustor

Ess

Gerlinger

2019

AIAA Propulsion and Energy 2019 Forum

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The lean burn combustion concept has shown potential for a further reduction of pollutants from aero engines. Partially premixed swirled flames in lean burn combustors strongly influence stability, performance and pollutant emissions associated with this concept and remain a major challenge when it comes to their prediction by numerical simulations. Large-Eddy Simulations (LES) for non-reactive and chemically reactive two-phase flows are performed for the DLR Generic Single Sector Combustor, which is a generic spray burner typical for lean burn combustors. Most simulations published on this kerosene burner do not accurately capture the lift-off height of the flame and the temperature distributions within the flow field. In contrast to previous scale-resolving simulations, the focus of this work is on LES, employing Finite-Rate Chemistry (FRC) for detailed combustion modeling. A reaction mechanism with 59 species and 372 elementary reactions and an Assumed Probability Density Function (APDF) approach for turbulence-chemistry interaction is used. The non-reacting mean velocity field, the spray distribution, flame shape, and flame lift-off height obtained from the simulations agree well with experimental data. In the flame, both premixed and diffusion-dominated regions are identified. Premixed zones occur predominantely, mainly as coherent structures in areas with high temperature gradients, whereas diffusion-dominated flame zones occur as isolated regions. For the detailed analysis of the burner, the employed numerical framework, including FRC, was found to be essential for an accurate prediction of the complex flame structure.

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Soot Modeling in a Turbulent Unconfined C2H4/Air Jet Flame

Cited by 9 publications

References 18 publications

Experimental characterization and numerical simulation of a sooting lifted turbulent jet diffusion flame

Experimental characterization and numerical simulation of a sooting lifted turbulent jet diffusion flame

Large Eddy Simulations of a Sooting Lifted Turbulent Jet-Flame

Large-Eddy Simulation of Spray Flames in the DLR Generic Single Sector Combustor

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