This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Automatic Mesh Generation for CFD Simulations of Direct-Injection Engines
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 14, 2015 by SAE International in United States
Annotation ability available
Prediction of in-cylinder flows and fuel-air mixing are two fundamental pre-requisites for a successful simulation of direct-injection engines. Over the years, many efforts were carried out in order to improve available turbulence and spray models. However, enhancements in physical modeling can be drastically affected by how the mesh is structured. Grid quality can negatively influence the prediction of organized charge motion structures, turbulence generation and interaction between in-cylinder flows and injected sprays. This is even more relevant for modern direct injection engines, where multiple injections and control of charge motions are employed in a large portion of the operating map. Currently, two different approaches for mesh generation exist: manual and automatic. The first makes generally possible to generate high-quality meshes but, at the same time, it is very time consuming and not completely free from user errors. Automatic mesh generation is very fast, but does not easily allow to align grid with flow and spray in regions of interest, for instance where fuel is injected or where the air flow is confined between pipe walls and thigh gaps (intake and exhaust head ducts and valve gaps). Within this context, the authors have developed a novel approach for automatic mesh generation, where both mesh quality and flow alignment are taken into account. Such methodology has been incorporated into the Lib-ICE code, which is based on the OpenFOAM technology. On the basis of combustion chamber details and/or user specified parameters (piston bowl points, injector direction, squish height, valve lift diagram,…), body fitted, high quality grids are automatically generated to perform full-cycle or compression/combustion simulations. To assess the proposed approach, two direct-injection engines were simulated. The first is Diesel fueled and only compression and combustion phases are simulated, showing the advantages of a spray-oriented grid, compared to a conventional Cartesian one, in terms of prediction of fuel-air mixing and combustion process. The second one is a gasoline, direct-injection engine. In this case full-cycle simulations were performed and computed flow field data were compared with optical experimental ones.
CitationLucchini, T., Della Torre, A., D'Errico, G., Montenegro, G. et al., "Automatic Mesh Generation for CFD Simulations of Direct-Injection Engines," SAE Technical Paper 2015-01-0376, 2015, https://doi.org/10.4271/2015-01-0376.
- Gosman A. D.. State of the Art of Multi-Dimensional Modeling of Engine Reacting Flows. Oil and Gas Science and Technology, 54(no. 2), 1999.
- Barths H., Hasse C., and Peters N.. Computational fluid dynamics modelling of non-premixed combustion in direct injection diesel engines. International Journal of Engine Research, 1 (3):pp. 249-267, 2000.
- Duclos J. P., Zolver M., and Baritaud T.. 3d Modeling of Combustion for DI-SI Engines. Oil and Gas Science and Technology, 54:pp. 259-264, 1999.
- Huh K. Y. and Gosman A. D.. A Phenomenological Model of Diesel Spray Atomization. Proceedings of the International Conference on Multiphase Flows, Tsukuba, Japan, 1991.
- Bai, C. and Gosman, A., “Mathematical Modelling of Wall Films Formed by Impinging Sprays,” SAE Technical Paper 960626, 1996, doi:10.4271/960626.
- Lucchini T., D'Errico G., and Ettorre D.. Numerical investigation of the spray-mesh-turbulence interactions for high-pressure, evaporating sprays at engine conditions. International Journal of Heat and Fluid Flow, 32:pp. 285-297, 2011.
- Dahms R. N., Drake M. C., Fansler T. D., Kuo T.-W., and Peters N.. Understanding ignition processes in spray-guided gasoline engines using high-speed imaging and the extended spark-ignition model SparkCIMM. Part A: Spark channel processes and the turbulent flame front propagation. Combustion and Flame., 158 (11):2229-2244, 2011.
- Senecal, P., Richards, K., Pomraning, E., Yang, T. et al., “A New Parallel Cut-Cell Cartesian CFD Code for Rapid Grid Generation Applied to In-Cylinder Diesel Engine Simulations,” SAE Technical Paper 2007-01-0159, 2007, doi:10.4271/2007-01-0159.
- Stapf, K., Menon, S., Schmidt, D., Rieß, M. et al., “Charge Motion and Mixture Formation Analysis of a DISI Engine Based on an Adaptive Parallel Mesh Approach,” SAE Technical Paper 2014-01-1136, 2014, doi:10.4271/2014-01-1136.
- Lucchini, T., D'Errico, G., Jasak, H., and Tukovic, Z., “Automatic Mesh Motion with Topological Changes for Engine Simulation,” SAE Technical Paper 2007-01-0170, 2007, doi:10.4271/2007-01-0170.
- Lucchini, T., D'Errico, G., Onorati, A., Bonandrini, G. et al., “Development of a CFD Approach to Model Fuel-Air Mixing in Gasoline Direct-Injection Engines,” SAE Technical Paper 2012-01-0146, 2012, doi:10.4271/2012-01-0146.
- Montenegro, G., Della Torre, A., Onorati, A., Broggi, D. et al., “CFD Simulation of a Sliding Vane Expander Operating Inside a Small Scale ORC for Low Temperature Waste Heat Recovery,” SAE Technical Paper 2014-01-0645, 2014, doi:10.4271/2014-01-0645.
- Montorfano, A., Piscaglia, F., and Onorati, A., “A LES Study on the Evolution of Turbulent Structures in Moving Engine Geometries by an Open-Source CFD Code,” SAE Technical Paper 2014-01-1147, 2014, doi:10.4271/2014-01-1147.
- Lucchini, T., Fiocco, M., Torelli, R., and D'Errico, G., “Automatic Mech Generation for Full-Cycle CFD Modeling of IC Engines: Application to the TCC Test Case,” SAE Technical Paper 2014-01-1131, 2014, doi:10.4271/2014-01-1131.
- Baum E., Peterson B., Bhm B., and Dreizler A.. On the validation of les applied to internal combustion engine flows: Part 1: Comprehensive experimental database. Flow, Turbulence and Combustion, 92(1-2):269-297, 2014.
- Lucchini T., D'Errico G., Brusiani F., and Bianchi G.. A Finite-Element Based Mesh Motion Technique for Internal Combustion Engine Simulations. COMODIA 2008, MS2-3, 2008.
- Nordin N.. Complex Chemistry Modeling of Diesel Spray Combustion. PhD thesis, Chalmers University of Technology, Department of Thermo Fluid Dynamics, 2001.
- Knupp P. M.. Algebraic mesh quality metrics for unstructured initial meshes. Finite Elements in Analysis and Design, Vol. 39:217-241, 2003.
- Jasak H.. Error Analysis and estimation for the finite volume method with applications to fluid flows. Ph.d thesis, Imperial College of Science, Tecnology and Medicine, London, 1996.
- Ferziger J. H. and Peric M.. Computational Methods for Fluid Dynamics. Springer, 2002.
- Singh S, Reitz RD, Musculus MPB, and Lachaux T. Validation of engine combustion models against detailed in-cylinder optical diagnostics data for a heavy-duty compression-ignition engine. International Journal of Engine Research, 8(1):97-126, 2007.
- Singh, S., Reitz, R., and Musculus, M., “Comparison of the Characteristic Time (CTC), Representative Interactive Flamelet (RIF), and Direct Integration with Detailed Chemistry Combustion Models against Optical Diagnostic Data for Multi-Mode Combustion in a Heavy-Duty DI Diesel Engine,” SAE Technical Paper 2006-01-0055, 2006, doi:10.4271/2006-01-0055.
- Chehroudi, B., Chen, S., Bracco, F., and Onuma, Y., “On the Intact Core of Full-Cone Sprays,” SAE Technical Paper 850126, 1985, doi:10.4271/850126.
- Reitz R. D.. Modeling Atomization Processes In High Pressure Vaporizing Sprays. Atomization and Spray Technology, Vol. 3:pp. 309-337, 1987.
- Baumgarten C. Mixture formation in internal combustion engines. Springer, 2006.
- Kong, S., Han, Z., and Reitz, R., “The Development and Application of a Diesel Ignition and Combustion Model for Multidimensional Engine Simulation,” SAE Technical Paper 950278, 1995, doi:10.4271/950278.
- Halmstead M. P., Kirsh L. J., and Quinn C. P.. The Autoignition of Hydrocarbon Fuels at High Temperatures and Pressures - Fitting of a Mathematical Model. Combustion and Flame, 30:45-60, 1977.
- D'Errico G., Lucchini T., Atzler F., and Rotondi R.. Computational fluid dynamics simulation of diesel engines with sophisticated injection strategies for in-cylinder pollutant controls. Energy & Fuels, 26(7):4212-4223, 2012.
- D'Errico, G., Lucchini, T., Di Gioia, R., and Bonandrini, G., “Application of the CTC Model to Predict Combustion and Pollutant Emissions in a Common-Rail Diesel Engine Operating with Multiple Injections and High EGR,” SAE Technical Paper 2012-01-0154, 2012, doi:10.4271/2012-01-0154.