High-performance Gasoline Direct Injection engine - 3D-CFD spray and combustion simulation

Nowadays the development of new internal combustion engines is significantly growing in complexity because of the challenging targets set by the governments and by the customer on its pollutant emissions and performance respectively. Moreover, the huge number of competitors in the automotive sector forces car manufacturers to strongly reduce the lead time of their new product in order to maintain a satisfactory level of profitability. Therefore, the development of reliable and predictive simulation tools is becoming crucial to investigate a wide range of innovative technical solutions and to reduce the number of expensive experimental campaign. In such a framework the goal of this thesis is the development of a 3D CFD model capable to reproduce the in-cylinder phenomena of a high-performance Direct Injection Spark Ignition Engine. The work is mainly divided into two parts. The first one focuses on the calibration of the injection spray model. Experimental measurements and optical characterization of the injector were used to properly tune the calibration parameters of the subroutines for Primary and secondary breakups, transport and evaporation phenomena. In this phase the definition of main grid settings was also performed. The second part deals with the simulation of the entire engine cycle and in particular of the combustion process. A detailed chemical kinetics solver (SAGE) was used to analytically solve combustion reactions. Different gasoline surrogates are tested and the results, in term of in-cylinder pressure trace and Heat Release Rate (HRR) shows a good agreements with the data measured at the engine test rig.