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Combustion and pollutant formation in a new recently introduced Common-Rail DI Diesel engine concept with roof-shaped combustion chamber and tumble charge motion are numerically investigated using the Representative Interactive Flamelet concept (RIF). A reference case with a cup shaped piston bowl for full load operating conditions is considered in detail. In addition to the reference case, three more cases are investigated with a variation of start of injection (SOI). A surrogate fuel consisting of n-decane (70% liquid volume fraction) and α-methylnaphthalene (30% liquid volume fraction) is used in the simulation. The underlying complete reaction mechanism comprises 506 elementary reactions and 118 chemical species. Special emphasis is put on pollutant formation, in particular on the formation of NOx, where a new technique based on a three-dimensional transport equation within the flamelet framework is applied.

Understanding external vehicle aerodynamics is an integral step in reducing overall vehicle fuel consumption. This is particularly true for long-haul commercial vehicles where an incremental decrease in drag can translate into significant fuel savings based on the number of miles traveled over the course of a truck's working life. The ability to critically analyze the air motion adjacent to commercial vehicles is a step toward understanding the overall affects of external aerodynamics on the entire vehicle. To achieve this understanding, the aerodynamics problem must be divided into manageable tasks that can each yield qualitative and quantitative results. A two-dimensional (2D) External Aerodynamics Tool (EAT) has been developed that enables computational fluid dynamics (CFD) simulations of commercial vehicles to be performed quickly and easily.