| Autor: |
Richard, S., Bougrine, S., Font, G., Lafossas, F.-A., Le Berr, F., Richard, S., Bougrine, S., Font, G., Lafossas, F.-A., Le Berr, F. |
| Zdroj: |
Oil & Gas Science and Technology - Revue de l'IFP; May 2009, Vol. 64 Issue: 3 p223-242, 20p |
| Abstrakt: |
In the automotive industry, today's major objectives concern the reduction of pollutant emissions and fuel consumption while improving performance and driveability. For this purpose, during the last decade, the classical engine has evolved towards a very complex system combining many hi-tech components with advanced control strategies. Optimizing the whole engine system and controlling its behaviour has then become a real challenge for car manufacturers. In this context, powertrain simulation tools have been shown to be an undisputable support during all stages of the engine development from concept design to control strategies development and calibration. However these tools require sophisticated models to be efficient, especially in the combustion chamber where combustion and pollutant formation processes take place. This paper presents a 0D physical combustion model devoted to the prediction of heat release, knock and pollutants in SI engines. The originality of the model derives from the fact it is based on the reduction of the 3D CFD E-CFM (Extended Coherent Flame Model) model developed at IFP. The CFM formalism distinguishes two zones: the fresh and the burnt gases, which are separated by a flame front and are both described by their temperature, mass and composition. The proposed model is an important evolution of the CFM-1D model previously published. It computes the rate of consumption of the fresh gases and is based on the calculation of the flame front surface using the real engine geometry and a 0D derivation of the flame surface density approach. Pollutants (CO and NOx) are computed both through the flame front an within the burnt gases using a reduced kinetic scheme and a classical extended Zel'dovitch mechanism. The knock timing calculation is performed in the fresh gases zone describing the evolution of an auto-ignition precursor and a simple correlation is used to estimate the corresponding knock intensity. The whole model is validated against experimental data at several steady state operating points for a single-cylinder engine. Parametric variations around optimal engine settings are also performed. A good agreement with experiments is observed, showing the interest of reducing 3D CFD models to build predictive 0D models for engine system simulations. |
| Databáze: |
Supplemental Index |
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