Application of Tabulated Detailed Chemistry to LES Model of Diesel ICE Combustion

2019 ◽  
Author(s):  
Oldrich Vitek ◽  
Vit Dolecek ◽  
Dmitry Goryntsev ◽  
Ferry Tap ◽  
Zoran Pavlovic ◽  
...  
Keyword(s):  
Predictive Ability ◽  
Industrial Applications ◽  
Computational Time ◽  
Combustion Model ◽  
Cfd Simulations ◽  
Detailed Chemistry ◽  
Tabulated Chemistry ◽  
Les Model ◽  
D Model ◽  
Fuel Surrogates

Abstract The use of 3-D CFD combustion models based on tabulated chemistry is becoming increasingly popular. Especially the runtime benefit is attractive, as the tabulated chemistry method allows including state-of-the-art chemical reaction schemes in CFD simulations without significant penalties in terms of computational time. In this work, the Tabkin FGM combustion model in AVL FIRE is used to perform LES simulations of a diesel ICE (AVL SCRE). Four load conditions are investigated with three different fuel surrogates. Predicted data are compared with reference ones (measurements or data from calibrated 0-D/1-D model) while discussing differences between them. CPU benefits are quantified. The main conclusion is that such CFD model has high predictive ability while requiring low calibration effort and being relatively fast, hence it is an interesting alternative to RANS-based industrial applications.

Validation of URANS Simulation of Truck Cooling Fan Performance

2014 ◽  
Author(s):  
Sassan Etemad ◽  
Peter Gullberg
Keyword(s):  
Test Data ◽  
Industrial Applications ◽  
Ideal Gas ◽  
Computational Time ◽  
Constant Density ◽  
Cfd Simulations ◽  
Simulation Accuracy ◽  
Cooling Fan ◽  
Density Assumption ◽  
Urans Cfd

The performance of an axial heavy duty truck cooling fan was investigated by measurements in a test rig and by CFD simulations. In order to account for the unsteadiness of the flow, URANS simulations were employed. Good agreement was achieved between the simulation and test data, in particular in the axial regime, despite the constant density assumption. To improve the simulation accuracy in the radial and transitional regime it is most likely insufficient to assume constant density. New simulations with ideal gas assumptions for these regimes are believed to give better agreement with the test data. The simulations show that URANS CFD can produce results very close to the ones obtained in the test facilities and thereby can be used for the industrial applications when flow unsteadiness has to be taken into account. The fact that it requires long computational time and is CPU-demanding can no longer be regarded as a major preventing factor for its application in the industry. In addition, it provides valuable information about the details of the flow which can contribute to the optimization of the geometry for improved efficiency and higher performance.

Predictive CFD Modeling of Diesel Engine Combustion Using an Efficient Workflow Based on Tabulated Chemistry

2018 ◽  
Author(s):  
Ferry Tap ◽  
Casper Meijer ◽  
Dmitry Goryntsev ◽  
Anton Starikov ◽  
Mijo Tvrdojevic ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Best Practice ◽  
Soot Formation ◽  
Cfd Modeling ◽  
Combustion Model ◽  
Large Set ◽  
Cfd Simulations ◽  
Experimental Database ◽  
Tabulated Chemistry ◽  
Wide Range

The use of 3D CFD combustion models based on tabulated chemistry is becoming increasingly popular. Especially the runtime benefit is attractive, as the tabulated chemistry method allows to include state-of-the-art chemical reaction schemes in CFD simulations. In this work, the Tabkin FGM combustion model in AVL FIRE™ is used to assess the predictivity on a large database of a light-duty Diesel engine measurements. The AVL TABKIN™ software is used to create the chemistry look-up tables for the Tabkin FGM model. The TABKIN software has been extended with the kinetic soot model, where the soot mass fraction calculation is done during the chemistry tabulation process, as well as an NO model using a second progress variable. From recent validation studies, a best-practice and nearly automated workflow has been derived to create the look-up tables for Diesel engine applications based on minimal input. This automated modeling workflow is assessed in the present study. A wide range of parameter variations are investigated for 5 engine load points, with and without EGR, in total 186 cases. This large number of CFD simulations is run in an automated way and the parameters of the CFD sub-models are kept equal as well as all numerical settings. Results are presented for combustion and emissions (NO and soot). Combustion parameters and NO emissions correlate very well to the experimental database with R2 values above 0.95. Soot predictions give order-of-magnitude agreement for most of the cases; the trend however is not always respected, which limits the overall correlation for all cases together, as reported by other authors. Further fundamental research on modeling soot formation and oxidation process remains required to improve the models. In terms of CPU time, the present study was executed on an off-the-shelf HPC cluster, using 8 CPU cores per case and requiring around 3 hrs of wall-time per case, e.g. such a large set of calculations can be simulated overnight on a standard HPC cluster.

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

Entropy ◽  
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.

Comparison of Temperature Fields and Emissions Predictions Using Both an FGM Combustion Model, With Detailed Chemistry, and a Simple Eddy Dissipation Combustion Model With Simple Global Chemistry

2017 ◽  
Author(s):  
Pierre Q. Gauthier
Keyword(s):  
Mixture Fraction ◽  
Temperature Fields ◽  
Combustion Model ◽  
Detailed Chemistry ◽  
Combustion Modeling ◽  
Flamelet Generated Manifold ◽  
Wide Range ◽  
Turbulence Effects ◽  
Air Chemistry ◽  
Dissipation Model

The detailed modeling of the turbulence-chemistry interactions occurring in industrial flames has always been the leading challenge in combustion Computational Fluid Dynamics (CFD). The wide range of flame types found in Industrial Gas Turbine Combustion systems has exacerbated these difficulties greatly, since the combustion modeling approach must be able to predict the flames behavior from regions of fast chemistry, where turbulence has no significant impact on the reactions, to regions where turbulence effects play a significant role within the flame. One of these combustion models, that is being used more and more in industry today, is the Flamelet Generated Manifold (FGM) model, in which the flame properties are parametrized and tabulated based on mixture fraction and flame progress variables. This paper compares the results obtained using an FGM model, with a GRI-3.0 methane-air chemistry mechanism, against the more traditional Industrial work-horse, Finite-Rate Eddy Dissipation Model (FREDM), with a global 2-step Westbrook and Dryer methane-air mechanism. Both models were used to predict the temperature distributions, as well as emissions (NOx and CO) for a conventional, non-premixed, Industrial RB211 combustion system. The object of this work is to: (i) identify any significant differences in the predictive capabilities of each model and (ii) discuss the strengths and weakness of both approaches.

Machine Vision Based Non-Magnetic Object Detection and Removal on Moving Conveyors in Steel Industry through Differential Techniques

2012 ◽  
Vol 2 (3) ◽  
pp. 59-70
Author(s):  
K. C. Manjunatha ◽  
H. S. Mohana ◽  
P. A. Vijaya
Keyword(s):  
Object Detection ◽  
Steel Industry ◽  
Material Handling ◽  
Raw Materials ◽  
Industrial Applications ◽  
Vital Role ◽  
Raw Material ◽  
Computational Time ◽  
Video Input ◽  
Intelligent Process

Intelligent process control technology in various manufacturing industries is important. Vision based non-magnetic object detection on moving conveyor in the steel industry will play a vital role for intelligent process and raw material handling. This paper presents an approach for a vision based system which performs the detection of non-magnetic objects on raw material moving conveyor in a secondary steel making industry. At single camera level, a vision based differential algorithm is applied to recognize an object. Image pixels based differential techniques; optical flow and motion based segmentations are used for traffic parameters extraction, the proposed approach extends those futures into industrial applications. The authors can implement smart control system, since they can save the energy and control unnecessary breakdowns in a robust manner. The technique developed for non-magnetic object detection is having single static background. Establishing background and background subtraction from continuous video input frames forms the basis. Detection of non-magnetic materials which are moving with raw materials and taking immediate action at the same stage as material handling system will avoid the breakdowns or power wastage. The authors achieve accuracy up to 95% with the computational time of not more than 1.5 seconds for complete system execution.

COMPUTATIONAL STUDY ON COMBUSTION AND EMISSION CHARACTERISTIC OF PILOTED FLAMES BY VARYING COMPOSITION CO2 OF SIMULATED BIOGAS

2017 ◽  
Vol 79 (7-3) ◽  
Author(s):  
Khor Chin Keat ◽  
M. F. Mohd Yasin ◽  
M. A. Wahid ◽  
A. Saat ◽  
A. S. Md Yudin
Keyword(s):  
Computational Study ◽  
Flame Temperature ◽  
Dilution Effect ◽  
Co2 Concentration ◽  
Nox Emission ◽  
Combustion Model ◽  
Emission Characteristic ◽  
Measured Temperature ◽  
Flamelet Model ◽  
Detailed Chemistry

This study investigates the performance of flamelet model technique in predicting the behavior of piloted flame.A non-premixed methane flame of a piloted burner is simulated in OpenFOAM. A detailed chemistry of methane oxidation is integrated with the flamelet combustion model using probability density function (pdf) approach. The turbulence modelling adopts Reynolds Average Navier Stokes (RANS) framework with standard k-ε model. A comparison with experimental data demonstrates good agreement between the predicted and the measured temperature profiles in axial and radial directions. Recently, one of major concern with combustion system is the emission of pollution specially NOx emission. Reduction of the pollutions can be achieved by varying the composition of CO2 in biogas. In addition, the effect of the composition of biogas on NOx emission of piloted burner is still not understood. Therefore, understanding the behavior composition of CO2 in biogas is important that could affect the emission of pollution. In the present study, the use of biogas with composition of 10 to 30 percent of CO2 is simulated to study the effects of biogas composition on NOx emission. The comparison between biogas and pure methane are done based on the distribution of NOx, CO2, CH4, and temperature at different height above the burner. At varying composition of CO2 in biogas, the NOx emission for biogas with 30 percent CO2 is greatly reduced compared to that of 10 percent CO2. This is due to the reduction of the post flame temperature that is produced by the dilution effect at high CO2 concentration.  

scholarly journals Scale-Resolving Simulation of a Propane-Fuelled Industrial Gas Turbine Combustor Using Finite-Rate Tabulated Chemistry

Fluids ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 126 ◽  
Author(s):  
Kai Zhang ◽  
Ali Ghobadian ◽  
Jamshid M. Nouri
Keyword(s):  
Gas Turbine ◽  
Chemical Reaction ◽  
Turbulent Flame ◽  
Lower Amount ◽  
Combustion Model ◽  
Gas Turbine Combustor ◽  
Finite Rate ◽  
Chemistry Method ◽  
Tabulated Chemistry ◽  
Partially Premixed

The scale-resolving simulation of a practical gas turbine combustor is performed using a partially premixed finite-rate chemistry combustion model. The combustion model assumes finite-rate chemistry by limiting the chemical reaction rate with flame speed. A comparison of the numerical results with the experimental temperature and species mole fraction clearly showed the superiority of the shear stress transport, K-omega, scale adaptive turbulence model (SSTKWSAS). The model outperforms large eddy simulation (LES) in the primary region of the combustor, probably for two reasons. First, the lower amount of mesh employed in the simulation for the industrial-size combustor does not fit the LES’s explicit mesh size dependency requirement, while it is sufficient for the SSTKWSAS simulation. Second, coupling the finite-rate chemistry method with the SSTKWSAS model provides a more reasonable rate of chemical reaction than that predicted by the fast chemistry method used in LES simulation. Other than comparing with the LES data available in the literature, the SSTKWSAS-predicted result is also compared comprehensively with that obtained from the model based on the unsteady Reynolds-averaged Navier–Stokes (URANS) simulation approach. The superiority of the SSTKWSAS model in resolving large eddies is highlighted. Overall, the present study emphasizes the effectiveness and efficiency of coupling a partially premixed combustion model with a scale-resolving simulation method in predicting a swirl-stabilized, multi-jets turbulent flame in a practical, complex gas turbine combustor configuration.

scholarly journals Validation of an Eulerian Stochastic Fields Solver Coupled with Reaction–Diffusion Manifolds on LES of Methane/Air Non-premixed Flames

2020 ◽  
Author(s):  
Paola Breda ◽  
Chunkan Yu ◽  
Ulrich Maas ◽  
Michael Pfitzner
Keyword(s):  
Transport Model ◽  
Reaction Diffusion ◽  
Passive Scalar ◽  
Scalar Dissipation ◽  
Combustion Model ◽  
Filtered Density Function ◽  
Detailed Chemistry ◽  
Stochastic Fields ◽  
Reduced Chemistry ◽  
Flame Behavior

AbstractThe Eulerian stochastic fields (ESF) combustion model can be used in LES in order to evaluate the filtered density function to describe the process of turbulence–chemistry interaction. The method is typically computationally expensive, especially if detailed chemistry mechanisms involving hydrocarbons are used. In this work, expensive computations are avoided by coupling the ESF solver with a reduced chemistry model. The reaction–diffusion manifold (REDIM) is chosen for this purpose, consisting of a passive scalar and a suitable reaction progress variable. The latter allows the use of a constant parametrization matrix when projecting the ESF equations onto the manifold. The piloted flames Sandia D–E were selected for validation using a 2D-REDIM. The results show that the combined solver is able to correctly capture the flame behavior in the investigated sections, although local extinction is underestimated by the ESF close to the injection plate. Hydrogen concentrations are strongly influenced by the transport model selected within the REDIM tabulation. A total solver performance increase by a factor of 81% is observed, compared to a full chemistry ESF simulation with 19 species. An accurate prediction of flame F instead required the extension of the REDIM table to a third variable, the scalar dissipation rate.

scholarly journals On Numerical Simulation of Casting in New Foundries: Dynamic Process Simulations

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 886
Author(s):  
Amir M. Horr ◽  
Johannes Kronsteiner
Keyword(s):  
Numerical Simulation ◽  
Casting Process ◽  
Industrial Applications ◽  
Computational Time ◽  
Dynamic Processes ◽  
Numerical Techniques ◽  
Process Improvements ◽  
Innovative Methods ◽  
Process Simulations ◽  
Complex Casting

New and more complex casting technologies are growing, and foundries are using innovative methods to reduce cost and energy consumption and improve their product qualities. Numerical techniques, as tools to design and examine the process improvements, are also evolving continuously to embrace modelling of more dynamic systems for industrial applications. This paper will present a fresh approach towards the numerical simulation of dynamic processes using an evolving and dynamic mesh technique. While the conventional numerical techniques have been employed for these dynamic processes using a fixed domain approach, the more realistic evolving approach is used herein to match the complex material processes in new foundries. The underpinning of this new dynamic approach is highlighted by an evolving simulation environment where multiple mesh entities are appended to the existing numerical domain at timesteps. Furthermore, the change of the boundary and energy sources within casting process simulations have rationally been presented and its profound effects on the computational time and resources have been examined. The discretization and solver computational features of the technique are presented and the evolution of the casting domain (including its material and energy contents) during the process is described for semi-continuous casting process applications.

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