CFD modeling of combustion and pollutant emissions for a light duty engine under different operating conditions

In this work a CFD analysis in a traditional Diesel direct injection engine is addressed, by means of the OpenFOAM tool. The F1C engine geometry and the experimental data for a wide set of engine operating conditions are provided by Fiat Powertrain Technologies research centre. A specific solver for the fuel injection and combustion simulations is used. The Eulerian-Lagrangian approach is adopted for the spray modelling, the KHRT model is chosen to describe the particles breakup. The capability to predict the spray structure is observed in terms of spray penetration and mixture fraction distribution for a non-reacting flow. Two different schemes for the equations discretization are compared. The quality of the generated hexahedral, spray-oriented mesh seems enough if compared with the widely validated vessel pyramidal mesh. The combustion model used is the Representative Interactive Flamelet model which is based on the flamelet concept, turbulence-chemistry interaction is considered and a comprehensive chemical kinetics mechanism is adopted. The mesh sensitivity analysis and the combustion model validation are performed. It is observed that the pressure trend is correctly reproduced and the heat release quite well predicted. The results analysis is finally extended to the all set of operating conditions and significant parameters are studied. Moreover, the NO and CO emission levels are compared with experimental data. Only one of the proposed models for NO prediction can be considered validated.