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Bowl Geometry Effects on Turbulent Flow Structure in a Direct Injection Diesel Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
Published September 10, 2018 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
Diesel piston bowl geometry can affect turbulent mixing and therefore it impacts heat-release rates, thermal efficiency, and soot emissions. The focus of this work is on the effects of bowl geometry and injection timing on turbulent flow structure. This computational study compares engine behavior with two pistons representing competing approaches to combustion chamber design: a conventional, re-entrant piston bowl and a stepped-lip piston bowl. Three-dimensional computational fluid dynamics (CFD) simulations are performed for a part-load, conventional diesel combustion operating point with a pilot-main injection strategy under non-combusting conditions. Two injection timings are simulated based on experimental findings: an injection timing for which the stepped-lip piston enables significant efficiency and emissions benefits, and an injection timing with diminished benefits compared to the conventional, re-entrant piston.
While the flow structure in the conventional, re-entrant combustion chamber is dominated by a single toroidal vortex, the turbulent flow evolution in the stepped-lip combustion chamber depends more strongly on main injection timing. For the injection timing at which faster mixing controlled heat release and reduced soot emissions have been observed experimentally, the simulation predicts the formation of two additional recirculation zones created by interactions with the stepped-lip. Analysis of the CFD results reveals the mechanisms responsible for these recirculating flow structures. Vertical convection of outward radial momentum drives the formation of the recirculation zone in the squish region, while adverse pressure gradients drive flow inward near the cylinder head, thereby contributing to the formation of the second recirculation zone above the step. Bulk gas density is higher for the near-TDC injection timing than for the later injection timing. This leads to increased air entrainment into the sprays and slower spray velocities, so the sprays take longer to interact with the step, and beneficial recirculating flow structures are not obseved.
CitationBusch, S., Zha, K., Perini, F., Reitz, R. et al., "Bowl Geometry Effects on Turbulent Flow Structure in a Direct Injection Diesel Engine," SAE Technical Paper 2018-01-1794, 2018, https://doi.org/10.4271/2018-01-1794.
Data Sets - Support Documents
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- Crosse, J., “Going Clean-Off Highway,” Ricardo Quarterly Review Q2, 2010.
- Styron, J., Baldwin, B., Fulton, B., Ives, D. et al., “Ford 2011 6.7L Power Stroke® Diesel Engine Combustion System Development,” SAE Technical Paper 2011-01-0415, 2011, doi:10.4271/2011-01-0415.
- Zha, K., Busch, S., Warey, A., Peterson, R.C. et al., “A Study of Piston Geometry Effects on Late-Stage Combustion in a Light-Duty Optical Diesel Engine Using Combustion Image Velocimetry,” SAE Technical Paper 2018-01-0230, 2018, doi:10.4271/2018-01-0230.
- Busch, S., Zha, K., Perini, F., Reitz, R. et al., “Experimental and Numerical Studies of Bowl Geometry Impacts on Thermal Efficiency in a Light-Duty Diesel Engine,” SAE Technical Paper 2018-01-0228, 2018.
- Arcoumanis, C., Bicen, A.F., and Whitelaw, J.H., “Squish and Swirl-Squish Interaction in Motored Model Engines,” Journal of Fluids Engineering 105(1):105-112, 1983, doi:10.1115/1.3240925.
- Miles, P.C., RempelEwert, B.H., and Reitz, R.D., “Squish-Swirl and Injection-Swirl Interaction in Direct-Injection Diesel Engines,” presented at the ICE2003 6th International Conference on Engines for Automobiles, Capri, Italy, 9/14/2003-9/19/2003.
- Miles, P.C., Megerle, M., Hammer, J., Nagel, Z. et al., “Late-Cycle Turbulence Generation in Swirl-Supported, Direct-Injection Diesel Engines,” SAE Technical Paper 2002-01-0891, 2002, doi:10.4271/2002-01-0891.
- Miles, P.C., Turbulent Flow Structure in Direct-Injection, Swirl-Supported Diesel Engines,” in Flow and Combustion in Reciprocating Engines, (Berlin: Springer-Verlag, 2008), doi:10.1007/978-3-540-68901-0_4.
- Dolak, J.G., Shi, Y., and Reitz, R.D., “A Computational Investigation of Stepped-Bowl Piston Geometry for a Light Duty Engine Operating at Low Load,” SAE Technical Paper 2010-01-1263, 2010, doi:10.4271/2010-01-1263.
- Eder, T., Lückert, P., Kemmner, M., and Sass, H., “OM654-Launch of a New Engine Family by Mercedes-Benz,” MTZ Worldwide 77(3):60-67, 2016.
- Li, X., Sun, Z., Du, W., and Wei, R., “Research and Development of Double Swirl Combustion System for a DI Diesel Engine,” Combustion Science and Technology 182(8):1029-1049, 2010, doi:10.1080/00102200903544271.
- Yoo, D., Kim, D., Jung, W., Kim, N. et al., “Optimization of Diesel Combustion System for Reducing PM to Meet Tier4-Final Emission Regulation without Diesel Particulate Filter,” SAE Technical Paper 2013-01-2538, 2013, doi:10.4271/2013-01-2538.
- Kurtz, E.M. and Styron, J., “An Assessment of Two Piston Bowl Concepts in a Medium-Duty Diesel Engine,” SAE Int. J. Engines 5(2):344-352, 2012, doi:10.4271/2012-01-0423.
- Perini, F., Zha, K., Busch, S., and Reitz, R., “Comparison of Linear, Non-Linear and Generalized RNG-Based k-Epsilon Models for Turbulent Diesel Engine Flows,” SAE Technical Paper 2017-01-0561, 2017, doi:10.4271/2017-01-0561.
- Wang, B.-L., Miles, P.C., Reitz, R.D., Han, Z. et al., “Assessment of RNG Turbulence Modeling and the Development of a Generalized RNG Closure Model,” SAE Technical Paper 2011-01-0829, 2011, doi:10.4271/2011-01-0829.
- ECN Data Search Page, Engine Combustion Network Website, [cited 8/11/2017]; Available from: https://ecn.sandia.gov/ecn-data-search/.
- Perini, F. and Reitz, R.D., “Improved Atomization, Collision and Sub-Grid Scale Momentum Coupling Models for Transient Vaporizing Engine Sprays,” International Journal of Multiphase Flow 79:107-123, 2015, doi:10.1016/j.ijmultiphaseflow.2015.10.009.
- Busch, S., “Light-Duty Diesel Combustion,” presented at the DOE Vehicle Technologies Office and Hydrogen and Fuel Cells Program Annual Merit Review, Washington, DC, June 6, 2017, available online: https://energy.gov/eere/vehicles/downloads/vehicle-technologies-office-merit-review-2017-light-duty-diesel-combustion.
- Reitz, R.D. and Bracco, F.B., “On the Dependence of Spray Angle and other Spray Parameters on Nozzle Design and Operating Conditions,” SAE Technical Paper 790494, 1979, doi:10.4271/790494.
- Beale, J.C. and Reitz, R.D., “Modeling Spray Atomization with the Kelvin-Helmholtz/Rayleigh-Taylor Hybrid Model,” Atomization and Sprays 9(6):623-650, 1999, doi:10.1615/Atomiz Spr.v9.i6.40.
- Munnannur, A. and Reitz, R.D., “Comprehensive Collision Model for Multidimensional Engine Spray Computations,” Atomization and Sprays 19(7):597-619, 2009, doi:10.1615/AtomizSpr.v19.i7.10.
- Torres, D.J., O'Rourke, P.J., and Amsden, A.A., “A Discrete Multicomponent Fuel Model,” Atomization and Sprays 13(2&3):42, 2003, doi:10.1615/AtomizSpr.v13.i23.10.
- Engine Combustion Network Website, “Small-Bore Diesel Engine,” [cited 8/11/2017]; Available from: https://ecn.sandia.gov/engines/engine-facilities/small-bore-diesel-engine/.
- Perini, F., Zha, K., Busch, S., Miles, P. et al., “Principal Component Analysis and Study of Port-Induced Swirl Structures in a Light-Duty Optical Diesel Engine,” SAE Technical Paper 2015-01-1696, 2015, doi:10.4271/2015-01-1696.
- Xu, H., “Some Critical Technical Issues on the Steady Flow Testing of Cylinder Heads,” SAE Technical Paper 2001-01-1308, 2001, doi:10.4271/2001-01-1308.
- Perini, F., Zha, K., Busch, S., Kurtz, E. et al., “Piston Geometry Effects in a Light-Duty, Swirl-Supported Diesel Engine: Flow Structure Characterization,” International Journal of Engine Research, 2017, doi:10.1177/1468087417742572.
- Busch, S. and Miles, P.C., “Parametric Study of Injection Rates with Solenoid Injectors in an Injection Quantity and Rate Measuring Device,” Journal of Engineering for Gas Turbines and Power 137(10):101503-101503, 2015, doi:10.1115/1.4030095.
- Sahoo, D., Miles, P.C., Trost, J., and Leipertz, A., “The Impact of Fuel Mass, Injection Pressure, Ambient Temperature, and Swirl Ratio on the Mixture Preparation of a Pilot Injection,” SAE Int. J. Engines 6(3):1716-1730, doi:10.4271/2013-24-0061.
- Su, W., Lin, R., Xie, H., and Shi, S.-x., “Enhancement of Near Wall Mixing of an Impinging Jet by Means of a Bump on the Wall,” SAE Technical Paper 971616, 1997, doi:10.4271/971616.
- Su, W., Lin, T.J., Zhao, H., and Pei, Y.Q., “Research and Development of an Advanced Combustion System for the Direct Injection Diesel Engine,” Proceedings of the Institution of Mechanical Engineers Part D-Journal of Automobile Engineering 219:241-252, 2005, doi:10.1243/095440705X6604.
- Ebara, T., Amagai, K., and Arai, M., “Penetration Model of a Diesel Spray along a Wall,” presented at the Fourth International Symposium COMODIA, Kyoto, Japan, July 20-23, 1998.
- Cornwell, R. and Conicella, F., “Direct Injection Diesel Engines,” Patent Number: US 8, 770,168 B2, July 8, 2014.
- Iikubo, S., Nakajima, H., Adachi, Y. and Shimokawa, K., “Combustion Chamber Structure for Direct Injection Diesel Engine,” Patent Number: US 8,156,927 B2, April 17, 2012.
- Naber, J.D. and Siebers, D.L., “Effects of Gas Density and Vaporization on Penetration and Dispersion of Diesel Sprays,” SAE Technical Paper 960034, 1996, doi:10.4271/960034.
- Arai, M., Amagai, K., and Ebara, T., “Attitude Control of a Diesel Spray under the Coanda Effect,” SAE Technical Paper 941923, 1994, doi:10.4271/941923.
- Zha, K., Busch, S., Miles, P.C., Wijeyakulasuriya, S. et al., “Characterization of Flow Asymmetry during the Compression Stroke Using Swirl-Plane PIV in a Light-Duty Optical Diesel Engine with the Re-Entrant Piston Bowl Geometry,” SAE Int. J. Engines 8(4):1837-1855, 2015, doi:10.4271/2015-01-1699.
- Perini, F., Ra, Y., Hiraoka, K., Nomura, K. et al., “An Efficient Level-Set Flame Propagation Model for Hybrid Unstructured Grids Using the G-Equation,” SAE Int. J. Engines 9(3):1409-1424, 2016, doi:10.4271/2016-01-0582.