Computational Study of the Effects of the Re-entrant Lip Shape and Toroidal Radii of Piston Bowl on a HSDI Diesel Engine's Performance and Emissions 2004-01-0118

The piston bowl design is one of the most important factors that affect the air/fuel mixing and the subsequent combustion and pollutant formation processes in a direct injection diesel engine. The bowl geometry and dimensions, such as pip region, bowl lip area, and torus radius are all known to have an effect on the in-cylinder mixing and combustion process. In order to understand better the effect of torus radius, three piston bowls with different torus radius and lip shapes designs but with the same lip area and pip inclination were investigated using Computational Fluid Dynamics (CFD) engine modelling. KIVA3V with improved sub-models was used to model the in-cylinder flows and combustion process, and it was validated on a High-Speed Direct Injection (HSDI) engine with a 2^nd generation common rail fuel injection system. The engine's performance, in-cylinder flow and combustion, and emission characteristics were analysed at maximum power and maximum torque conditions and a part-load operating conditions. Three injector protrusions and injection timings were investigated at full load and a part load conditions.