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The drive for substantial CO2 reductions in gasoline engines in the light of the Kyoto Protocol and higher fuel efficiencies has increased research on downsized, turbocharged engines. Via a higher intake air pressure, an increase in specific power output can be reached on a comparatively smaller sized engine, in order to ensure high torque capabilities, while allowing a fuel saving of about 20%. This fuel efficiency benefit includes the advantages of direct injection (DI) technology which avoids crossflow of fuel. This paper presents the capabilities of Computational Fluid Dynamics to aid in the development of such engines. Particularly, the IFP-C3D code offers several recently developed models which permit to estimate, with good accuracy, the evolution of the combustion under given working conditions. Moreover, the capability of the model to predict knock occurrence is very helpful for engine designers within the framework of development of new downsized turbocharged engines.

Future Diesel engines must comply with conflicting demands: more stringent emission standards and customer desire for “fun-to-drive” vehicles, i.e. higher torque and power output. Given such objectives, engine development investigates new clean combustion processes, such as low temperature combustion (LTC), highly premixed combustion (HPC) or homogeneous charge compression ignition (HCCI) combustion and the possibility to combine them with current solutions. Lately, IFP has developed a near zero NOx and particulate combustion process, the NADI™ concept, a dual mode engine application switching from a novel lean combustion process at part load to conventional Diesel combustion at full load. Given the complex nature of these new combustion processes, the concept development relies increasingly on three-dimensional Computational Fluid Dynamics (CFD) tools as they help grasp the basic phenomena at stake and reduce development time and costs.