PhD defense - B. Enaux

Large Eddy Simulation of a Spark-Ignition engine - Evaluation of cycle-to-cycle variations



Delivered by INP Toulouse
Speciality: Fluid dynamics

June 16, 2010 - CERFACS

A major challenge for the development of internal combustion engines is to improve fuel economy and to reduce pollutant emissions while maintaining or enhancing engine performances. New strategies using downsizing with high levels of exhaust gas recirculation have this potential, but can impact on the combustion stability and trigger high cycle-to-cycle variations (CCV). The objective of this thesis is to set a methodology based on Large Eddy Simulation (LES) to study CCV of a Spark-Ignition (SI) engine. A gradual approach is used : the numerical tool is ?rst evaluated on a motored axisymmetric piston-cylinder assembly, and then applied on a motored SI engine to validate the in-cylinder aerodynamic predictions. On this last con?guration, the coupling with the turbulent combustion model DTFLES is added to si- mulate two operating points of the indirect injection engine mode. Each of these simulations takes into account one or several modeling key points (tetrahedra with moving mesh, the modelings of shock and ignition, and chemical kinetics) previously tested in academic con?gurations. This research work shows that LES approach, in the context of massively parallel computing, can be used to study the CCV of a realistic SI engine.