DNS-driven analysis of the Flamelet/Progress Variable model assumptions on soot inception, growth, and oxidation in turbulent flames

2020 ◽  
Vol 214 ◽  
pp. 437-449 ◽  
Author(s):  
Achim Wick ◽  
Antonio Attili ◽  
Fabrizio Bisetti ◽  
Heinz Pitsch
Keyword(s):  
Turbulent Flames ◽  
Variable Model ◽  
Progress Variable

Evaluation of flamelet/progress variable model for laminar pulverized coal combustion

2017 ◽  
Vol 29 (8) ◽  
pp. 083607 ◽  
Author(s):  
Xu Wen ◽  
Haiou Wang ◽  
Yujuan Luo ◽  
Kun Luo ◽  
Jianren Fan
Keyword(s):  
Coal Combustion ◽  
Pulverized Coal ◽  
Pulverized Coal Combustion ◽  
Variable Model ◽  
Progress Variable

Evaluation of real-fluid flamelet/progress variable model for laminar hydrothermal flames

2019 ◽  
Vol 143 ◽  
pp. 232-241 ◽  
Author(s):  
Zhengwei Gao ◽  
Haiou Wang ◽  
Kun Luo ◽  
Changcheng Song ◽  
Chunguang Zhao ◽  
...  
Keyword(s):  
Variable Model ◽  
Progress Variable ◽  
Real Fluid

Modeling heavy-duty diesel engines using tabulated kinetics in a wide range of operating conditions

2020 ◽  
pp. 146808741989616 ◽  
Author(s):  
Qiyan Zhou ◽  
Tommaso Lucchini ◽  
Gianluca D’Errico ◽  
Gilles Hardy ◽  
Xingcai Lu
Keyword(s):  
Diesel Engines ◽  
Operating Conditions ◽  
Scalar Dissipation ◽  
Cylinder Pressure ◽  
Heavy Duty ◽  
Variable Model ◽  
Progress Variable ◽  
Wide Range ◽  
Heavy Duty Diesel ◽  
Operating Points

Fast and high-fidelity combustion models including detailed kinetics and turbulence chemistry interaction are necessary to support design and development of heavy-duty diesel engines. In this work, the authors intend to present and validate tabulated flamelet progress variable model based on tabulation of laminar diffusion flamelets for different scalar dissipation rate, whose predictability highly depends on the description of fuel–air mixing process in which engine mesh layout plays an important role. To this end, two grids were compared and assessed: in both grids, cells were aligned on the spray direction with such region being enlarged in the second one, where the near-nozzle and near-wall mesh resolution were also improved, which is expected to better account for both spray dynamics and flame–wall interaction dominating the combustion process in diesel engines. Flame structure, in-cylinder pressure, apparent heat release rate, and emissions for different relevant operating points were compared and analyzed to identify the most suitable mesh. Afterwards, simulations were carried out in a heavy-duty engine considering 20 operating points, allowing to comprehensively verify the validity of tabulated flamelet progress variable model. The results demonstrated that the proposed approach was capable to accurately predict in-cylinder pressure evolution and NO x formation across a wide engine map.

scholarly journals Comparison of Presumed PDF Models of Turbulent Flames

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Chen Huang ◽  
Andrei N. Lipatnikov
Keyword(s):  
Heat Release ◽  
Burning Velocity ◽  
Mixture Fraction ◽  
Beta Function ◽  
Reaction Rates ◽  
Turbulent Flames ◽  
Implicit Assumption ◽  
Dirac Delta ◽  
Progress Variable ◽  
The Mean

Over the past years, the use of a presumed probability density function (PDF) for combustion progress variable or/and mixture fraction has been becoming more and more popular approach to average reaction rates in premixed and partially premixed turbulent flames. Commonly invoked for this purpose is a beta-function PDF or a combination of Dirac delta functions, with the parameters of the two PDFs being determined based on the values of their first and second moments computed by integrating proper balance equations. Because the choice of any of the above PDFs appears to be totally arbitrary as far as underlying physics of turbulent combustion is concerned, the use of such PDFs implies weak sensitivity of the key averaged quantities to the PDF shape. The present work is aimed at testing this implicit assumption by comparing mean heat release rates, burning velocities, and so forth, averaged by invoking the aforementioned PDFs, with all other things being equal. Results calculated in the premixed case show substantial sensitivity of the mean heat release rate to the shape of presumed combustion-progress-variable PDF, thus, putting the approach into question. To the contrary, the use of a presumed mixture-fraction PDF appears to be a sufficiently reasonable simplification for modeling the influence of fluctuations in the mixture fraction on the mean burning velocity provided that the mixture composition varies within flammability limits.

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