Large Eddy Simulation of the Cyclic Variations in an Internal Combustion Engine

A Large-Eddy Simulation of several cycles of a spark-ignition engine with port fuel injection has been performed. The investigated engine is a modified Rotax-engine with one cylinder and four valves, built and measured (Heidenreich, Private communication) by the Institute of Reciprocating Engines of the University of Karlsruhe (IFKM). A recently modified (Magagnato et al., 2008) progress variable combustion model of Schmid et al., 1998 has been used in this computation. A subgrid-scale model for the LES recently proposed by Stolz (Stolz et al., 2003) called High-pass filtered Eddy-Viscosity model has been employed, which appears to be ideal for moving meshes. In order to predict cyclic variations of the combustion process, an additional transport equation for the mixing of the fuel to air ratio inside the combustion chamber is proposed and investigated in this paper. The predicted cylinder pressure vs. crank angle is then compared to measured results (Heidenreich, Private communication).