Thermo-chemical manifold reduction for tabulated chemistry modeling. Temperature and dilution constraints for smooth combustion reactors

With ever more stringent emissions and performance regulations, more emphasis and efforts have been made in accurate modeling of the combustion process and engine-out emissions in engine development. However, accurate modeling of the combustion process requires detailed chemistry. Highly detailed mechanisms typically include hundreds of species and thousands of reactions, and solution of such reaction set has been one of the largest bottlenecks in numerical modeling of the IC engine with CFD. Typically, the accuracy in chemistry modeling is sacrificed by reducing the mechanism size for the sake of computational efficiency. In this study, a lookup-table based approach is applied for modeling the combustion process in an HCCI engine. Instead of solving chemistry on-the-fly during the CFD simulations, the chemistry is solved for possible combination of thermodynamic and mixing conditions. The turbulence-chemistry interaction is considered using a flamelet approach. Then, the solution is stored in a table, such that chemistry information can be retrieved during the CFD simulation. The lookup-table method, referred to as Flamelet Generated Manifold (FGM), provides significant runtime reduction in CFD simulations with high fidelity chemistry modeling. The FGM model was applied to a canonical HCCI experiment from Sandia National Laboratory. The experiment examined the effect of different levels of fuel stratification on ignition and combustion of a gasoline HCCI engine. The different levels of stratification were generated by controlling the amount of directly injected fuel. This case has been highly challenging for modeling using traditional modeling approaches. With FGM, it was possible to use the most detailed reaction mechanism to describe the chemistry as completely as one can. The effect of different surrogates on modeling results was investigated as well. It was found that the one proposed by Gauthier showed the most promising results in reproducing the highly complicated combustion with partial fuel stratification.

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Transported PDF simulations of the Delft-jet-in-hot-coflow burner based on 3D FGM tabulated chemistry

Proceeding of THMT-12. Proceedings of the Seventh International Symposium On Turbulence, Heat and Mass Transfer Palermo, Italy, 24-27 September, 2012 ◽

10.1615/ichmt.2012.procsevintsympturbheattransfpal.1580 ◽

2012 ◽

Cited By ~ 3

Author(s):

G. Sarras ◽

M.K. Stollinger ◽

Dirk J.E.M. Roekaerts

Keyword(s):

Tabulated Chemistry

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Manifold reduction techniques for the comparison of crank angle-resolved particle image velocimetry (PIV) data and Reynolds-averaged Navier-Stokes (RANS) simulations in a spark ignition direct injection (SIDI) engine

International Journal of Engine Research ◽

10.1177/14680874211013134 ◽

2021 ◽

pp. 146808742110131

Author(s):

Xiaohang Fang ◽

Li Shen ◽

Christopher Willman ◽

Rachel Magnanon ◽

Giuseppe Virelli ◽

...

Keyword(s):

Flow Field ◽

Particle Image ◽

Direct Injection ◽

Linear Manifold ◽

Main Flow ◽

Navier Stokes ◽

Reduction Techniques ◽

Image Velocimetry ◽

Manifold Reduction ◽

Relevance Index

In this article, different manifold reduction techniques are implemented for the post-processing of Particle Image Velocimetry (PIV) images from a Spark Ignition Direct Injection (SIDI) engine. The methods are proposed to help make a more objective comparison between Reynolds-averaged Navier-Stokes (RANS) simulations and PIV experiments when Cycle-to-Cycle Variations (CCV) are present in the flow field. The two different methods used here are based on Singular Value Decomposition (SVD) principles where Proper Orthogonal Decomposition (POD) and Kernel Principal Component Analysis (KPCA) are used for representing linear and non-linear manifold reduction techniques. To the authors’ best knowledge, this is the first time a non-linear manifold reduction technique, such as KPCA, has ever been used in the study of in-cylinder flow fields. Both qualitative and quantitative studies are given to show the capability of each method in validating the simulation and incorporating CCV for each engine cycle. Traditional Relevance Index (RI) and two other previously developed novel indexes: the Weighted Relevance Index (WRI) and the Weighted Magnitude Index (WMI), are used for the quantitative study. The results indicate that both POD and KPCA show improvements in capturing the main flow field features compared to ensemble-averaged PIV experimental data and single cycle experimental flow fields while capturing CCV. Both methods present similar quantitative accuracy when using the three indexes. However, challenges were highlighted in the POD method for the selection of the number of POD modes needed for a representative reconstruction. When the flow field region presents a Gaussian distribution, the KPCA method is seen to provide a more objective numerical process as the reconstructed flow field will see convergence with an increasing number of modes due to its usage of Gaussian properties. No additional criterion is needed to determine how to reconstruct the main flow field feature. Using KPCA can, therefore, reduce the amount of analysis needed in the process of extracting the main flow field while incorporating CCV.

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Computational Modeling of Boundary Layer Flashback in a Swirling Stratified Flame Using a LES-Based Non-Adiabatic Tabulated Chemistry Approach

Entropy ◽

10.3390/e23050567 ◽

2021 ◽

Vol 23 (5) ◽

pp. 567

Author(s):

Xudong Jiang ◽

Yihao Tang ◽

Zhaohui Liu ◽

Venkat Raman

Keyword(s):

Boundary Layer ◽

Heat Loss ◽

Boundary Layers ◽

Gas Turbines ◽

Predictive Accuracy ◽

Safety Issue ◽

Combustion Model ◽

Tabulated Chemistry ◽

Lean Fuel ◽

Flame Flashback

When operating under lean fuel–air conditions, flame flashback is an operational safety issue in stationary gas turbines. In particular, with the increased use of hydrogen, the propagation of the flame through the boundary layers into the mixing section becomes feasible. Typically, these mixing regions are not designed to hold a high-temperature flame and can lead to catastrophic failure of the gas turbine. Flame flashback along the boundary layers is a competition between chemical reactions in a turbulent flow, where fuel and air are incompletely mixed, and heat loss to the wall that promotes flame quenching. The focus of this work is to develop a comprehensive simulation approach to model boundary layer flashback, accounting for fuel–air stratification and wall heat loss. A large eddy simulation (LES) based framework is used, along with a tabulation-based combustion model. Different approaches to tabulation and the effect of wall heat loss are studied. An experimental flashback configuration is used to understand the predictive accuracy of the models. It is shown that diffusion-flame-based tabulation methods are better suited due to the flashback occurring in relatively low-strain and lean fuel–air mixtures. Further, the flashback is promoted by the formation of features such as flame tongues, which induce negative velocity separated boundary layer flow that promotes upstream flame motion. The wall heat loss alters the strength of these separated flows, which in turn affects the flashback propensity. Comparisons with experimental data for both non-reacting cases that quantify fuel–air mixing and reacting flashback cases are used to demonstrate predictive accuracy.

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Reduction principle at work

Nonautonomous Dynamical Systems ◽

10.1515/msds-2020-0124 ◽

2021 ◽

Vol 8 (1) ◽

pp. 46-74

Author(s):

Christian Pötzsche ◽

Evamaria Russ

Keyword(s):

Center Manifold ◽

Reduction Principle ◽

Critical Stability ◽

Center Manifold Reduction ◽

Infinite Dimensional ◽

Linearized Stability ◽

Dichotomy Spectrum ◽

Nonautonomous Case ◽

Necessary And Sufficient ◽

Manifold Reduction

Abstract The purpose of this informal paper is three-fold: First, filling a gap in the literature, we provide a (necessary and sufficient) principle of linearized stability for nonautonomous difference equations in Banach spaces based on the dichotomy spectrum. Second, complementing the above, we survey and exemplify an ambient nonautonomous and infinite-dimensional center manifold reduction, that is Pliss’s reduction principle suitable for critical stability situations. Third, these results are applied to integrodifference equations of Hammerstein- and Urysohn-type both in C- and Lp -spaces. Specific features of the nonautonomous case are underlined. Yet, for the simpler situation of periodic time-dependence even explicit computations are feasible.

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3D Numerical Simulation of a Laminar Experimental SWQ Burner with Tabulated Chemistry

Flow Turbulence and Combustion ◽

10.1007/s10494-017-9851-9 ◽

2017 ◽

Vol 100 (2) ◽

pp. 535-559 ◽

Cited By ~ 7

Author(s):

A. Heinrich ◽

S. Ganter ◽

G. Kuenne ◽

C. Jainski ◽

A. Dreizler ◽

...

Keyword(s):

Numerical Simulation ◽

3D Numerical Simulation ◽

Tabulated Chemistry

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Diesel engine performance mapping using a parametrized mixing time model

International Journal of Engine Research ◽

10.1177/1468087417718115 ◽

2017 ◽

Vol 19 (2) ◽

pp. 202-213 ◽

Cited By ~ 3

Author(s):

Michal Pasternak ◽

Fabian Mauss ◽

Christian Klauer ◽

Andrea Matrisciano

Keyword(s):

Diesel Engine ◽

Fuel Injection ◽

Mixing Time ◽

Combustion Process ◽

Engine Performance ◽

Injection Timing ◽

Engine Control ◽

Reactor Model ◽

Time Model ◽

Tabulated Chemistry

A numerical platform is presented for diesel engine performance mapping. The platform employs a zero-dimensional stochastic reactor model for the simulation of engine in-cylinder processes. n-Heptane is used as diesel surrogate for the modeling of fuel oxidation and emission formation. The overall simulation process is carried out in an automated manner using a genetic algorithm. The probability density function formulation of the stochastic reactor model enables an insight into the locality of turbulence–chemistry interactions that characterize the combustion process in diesel engines. The interactions are accounted for by the modeling of representative mixing time. The mixing time is parametrized with known engine operating parameters such as load, speed and fuel injection strategy. The detailed chemistry consideration and mixing time parametrization enable the extrapolation of engine performance parameters beyond the operating points used for model training. The results show that the model responds correctly to the changes of engine control parameters such as fuel injection timing and exhaust gas recirculation rate. It is demonstrated that the method developed can be applied to the prediction of engine load–speed maps for exhaust NOx, indicated mean effective pressure and fuel consumption. The maps can be derived from the limited experimental data available for model calibration. Significant speedup of the simulations process can be achieved using tabulated chemistry. Overall, the method presented can be considered as a bridge between the experimental works and the development of mean value engine models for engine control applications.

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