Multidimensional modeling of diesel combustion by a detailed kinetic scheme and comparison with in-cylinder optical measurements

The present work aims at a comprehensive study of diesel combustion based on detailed kinetic modelling and experimental investigations performed on an optically accessible engine. A diesel fuel surrogate model of combustion is included in a three-dimensional CFD code properly designed for application to internal combustion engines. The fuel spray is treated by discrete droplet models tuned on the ground of measurements of penetration lengths effected in a vessel at controlled conditions. The detailed chemistry of the turbulent reacting flow is computed by means of the partially stirred reactor approximation, which leads to an appreciable computational economy. Test-bench experimental data allow the code validation and the assessment of its predictability as operating conditions are modified. Optical measurements clarify major physical and chemical aspects related to fuel autoignition and combustion evolution. The proposed approach is believed to be valuable in optimising performances of diesel engines equipped with Common Rail (CR) injection systems.