This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Refinement of a 0D Turbulence Model to Predict Tumble and Turbulent Intensity in SI Engines. Part II: Model Concept, Validation and Discussion
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 03, 2018 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
As known, reliable information about underlying turbulence intensity is a mandatory pre-requisite to predict the burning rate in quasi-dimensional combustion models. Based on 3D results reported in the companion part I paper, a quasi-dimensional turbulence model, embedded under the form of “user routine” in the GT-Power™ software, is here presented in detail. A deep discussion on the model concept is reported, compared to the alternative approaches available in the current literature. The model has the potential to estimate the impact of some geometrical parameters, such as the intake runner orientation, the compression ratio, or the bore-to-stroke ratio, thus opening the possibility to relate the burning rate to the engine architecture.
Preliminarily, a well-assessed approach, embedded in GT-Power commercial software v.2016, is utilized to reproduce turbulence characteristics of a VVA engine. This test showed that the model fails to predict tumble intensity for particular valve strategies, such LIVC, thus justifying the need for additional refinements.
The model proposed in this work is conceived to solve 3 balance equations, for mean flow kinetic energy, tumble vortex momentum, and turbulent kinetic energy (3-eq. concept). An extended formulation is also proposed, which includes a fourth equation for the dissipation rate, allowing to forecast the integral length scale (4-eq. concept).
The impact of the model constants is parametrically analyzed in a first step, and a tuning procedure is advised. Then, a comparison between the 3- and the 4-eq. concepts is performed, highlighting the advantages of the 3-eq. version, in terms of prediction accuracy of turbulence speed-up at the end of the compression stroke. An extensive 3-eq. model validation is then realized according to different valve strategies and engine speeds.
The user-model is then utilized to foresee the effects of main geometrical parameters analyzed in part I, namely the intake runner orientation, the compression ratio, and the bore-to-stroke ratio. A two-valve per cylinder engine is also considered. Temporal evolutions of 0D- and 3D-derived mean flow velocity, turbulent intensity, and tumble velocity present very good agreements for each investigated engine geometry and operating condition. The model, particularly, exhibits the capability to accurately predict the tumble trends by varying some geometrical parameter of the engine, which is helpful to estimate the related impact on the burning rate.
Summarizing, the developed 0D model well estimates the in-cylinder turbulence characteristics, without requiring any tuning constants adjustment with engine speed and valve strategy. In addition, it demonstrates the capability to properly take into account the intake duct orientation and the compression ratio without tuning adjustments. Some minor tuning variation allows predicting the effects of bore-to-stroke ratio, as well. Finally, the model is verified to furnish good agreements also for a two-valve per cylinder engine, and with reference to two different high-performance engines.
CitationBozza, F., Teodosio, L., De Bellis, V., Fontanesi, S. et al., "Refinement of a 0D Turbulence Model to Predict Tumble and Turbulent Intensity in SI Engines. Part II: Model Concept, Validation and Discussion," SAE Technical Paper 2018-01-0856, 2018, https://doi.org/10.4271/2018-01-0856.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
- Hires, S., Tabaczynski, R., and Novak, J., “The Prediction of Ignition Delay and Combustion Intervals for a Homogeneous Charge, Spark Ignition Engine,” SAE Tech. Paper 780232, 1978, doi:10.4271/780232.
- Blizard, N. and Keck, J., “Experimental and Theoretical Investigation of Turbulent Burning Model for Internal Combustion Engines,” SAE Tech. Paper 740191, 1974, doi:10.4271/740191.
- Morel, T., Rackmil, C., Keribar, R., and Jennings, M., “Model for Heat Transfer and Combustion in Spark Ignited Engines and its Comparison with Experiments,” SAE Tech. Paper 880198, 1988, doi:10.4271/880198.
- Richard, S., Bougrine, S., Font, G., Lafossas, F.A., and Le Berr, F., “On the Reduction of a 3D CFD Combustion Model to Build a Physical 0D Model for Simulating Heat Release, Knock and Pollutants in SI Engines,” Oil & Gas Science and Technology - Rev. IFP. 64(3):223-242, 2009, doi:10.2516/ogst/2008055.
- Gatowsky, J. and Heywood, J., “Flame Photographs in a Spark-Ignition Engine,” Combustion and Flame 56(1):71-81, 1984, doi:10.1016/0010-2180(84)90006-3.
- Gouldin, F., “An Application of Fractals to Modeling Premixed Turbulent Flames,” Combustion and Flame. 68(3):249-266, 1987, doi:10.1016/0010-2180(87)90003-4.
- Millo, F., Luisi, S., Borean, F., and Stroppiana, A., “Numerical and Experimental Investigation on Combustion Characteristics of a Spark Ignition Engine with an Early Intake Valve Closing Load Control,” Fuel 121:298-310, 2014, doi:10.1016/j.fuel.2013.12.047.
- Luo, X., Teng, H., Lin, Y., Li, B. et al., “A Comparative Study on Influence of EIVC and LIVC on Fuel Economy of a TGDI Engine Part II: Influences of Intake Event and Intake Valve Closing Timing on the Cylinder Charge Motion,” SAE Tech. Paper 2017-01-2246, 2017, doi:10.4271/2017-01-2246.
- Borgnakke, C., Arpaci, V., and Tabaczynski, R., “A Model for the Instantaneous Heat Transfer and Turbulence in a Spark Ignition Engine,” SAE Tech. Paper 800287, 1980, doi:10.4271/800287.
- Morel, T. and Mansour, N., “Modeling of Turbulence in Internal Combustion Engines,” SAE Tech. Paper 820040, 1982, doi:10.4271/820040.
- Morel, T. and Keribar, R., “A Model for Predicting Spatially and Time Resolved Convective Heat Transfer in Bowl-in-Piston Combustion Chambers,” SAE Tech. Paper 850204, 1985, doi:10.4271/850204.
- Sjeric, M., Kozarac, D., and Bogensperger, M., “Implementation of a Single Zone k-ε Turbulence Model in a Multi Zone Combustion Model,” SAE Tech. Paper 2012-01-0130, 2012, doi:10.4271/2012-01-0130.
- Dulbecco, A., Richard, S., Laget, O., and Aubret, P., “Development of a Quasi-Dimensional K-k Turbulence Model for Direct Injection Spark Ignition (DISI) Engines Based on the Formal Reduction of a 3D CFD Approach,” SAE Tech. Paper 2016-01-2229, 2016, doi:10.4271/2016-01-2229.
- Kim, N., Kim, J., Ko, I., Choi, H. et al., “A Study on the Refinement of Turbulence Intensity Prediction for the Estimation of in-Cylinder Pressure in a Spark-Ignited Engine,” SAE Tech. Paper 2017-01-0525, 2017, doi:10.4271/2017-01-0525.
- Lafossas, F., Colin, O., Le Berr, F., and Menegazzi, P., “Application of a New 1D Combustion Model to Gasoline Transient Engine Operation,” SAE Tech. Paper 2005-01-2107, 2005, doi:10.4271/2005-01-2107.
- Ramajo, D., Zanotti, A., and Nigro, N., “Assessment of a zero-Dimensional Model of Tumble in four-Valve High Performance Engine,” International Journal of Numerical Methods for Heat & Fluid Flow 17(8):770-787, 2007, doi:10.1108/09615530710825765.
- Achuth, M. and Mehta, P.S., “Predictions of Tumble and Turbulence in four-Valve Pentroof Spark Ignition Engines,” International Journal of Engine Research 2(3):209-227, 2001, doi:10.1243/1468087011545442.
- Grasreiner, S., Neumann, J., Luttermann, C., Wensing, M., and Hasse, C., “A Quasi-Dimensional Model of Turbulence and Global Charge Motion for Spark Ignition Engines with Fully Variable Valvetrains,” International Journal of Engine Research 15(7):805-816, 2014, doi:10.1177/1468087414521615.
- Fogla, N., Bybee, M., Mirzaeian, M., Millo, F. et al., “Development of a K-k-∊ Phenomenological Model to Predict in-Cylinder Turbulence,” SAE International Journal of Engines 10(2):562-575, 2017, doi:10.4271/2017-01-0542.
- Dai, W., Newman, C., and Davis, G., “Predictions of in-Cylinder Tumble Flow and Combustion in SI Engines with a Quasi-Dimensional Model,” SAE Tech. Paper 961962, 1996, doi:10.4271/961962.
- Jones, P. and Junday, J., “Full Cycle Computational Fluid Dynamics Calculations in a Motored four Valve Pent Roof Combustion Chamber and Comparison with Experiment,” SAE Tech. Paper 950286, 1995, doi:10.4271/950286.
- Khalighi, B., El Tahry, S., Haworth, D., and Huebler, M., “Computation and Measurement of Flow and Combustion in a Four-Valve Engine with Intake Variations,” SAE Tech. Paper 950287, 1995, doi:10.4271/950287.
- Bozza, F., De Bellis, V., Berni, F., D’Adamo, A., and Maresca, L., “Refinement of a 0D Turbulence Model to Predict Tumble and Turbulent Intensity in SI Engines. Part I: 3D Analyses,” SAE Technical Paper 2018-01-0850, 2018, doi:10.4271/2018-01-0850.
- De Bellis, V., Bozza, F., Fontanesi, S., Severi, E. et al., “Development of a Phenomenological Turbulence Model through a Hierarchical 1D/3D Approach Applied to a VVA Turbocharged Engine,” SAE International Journal of Engines 9(1):506-519, 2016, doi:10.4271/2016-01-0545.