Flow and Atomization Models for C.R. Diesel Engine CFD Simulation

In the present work, the authors investigate the spray evolution and, in particular, the atomization process in a diesel engine bowl by using the KIVA3-V computational code with different break-up models. After a preliminary test of the break-up models sensitivity to the grid size and topology, the same atomization models are employed for the two-phase flow calculation in the combustion chamber of a common rail, turbocharged diesel engine conceived for future HCCI applications. The computations are extended to the combustion process in order to proceed with an overall validation with experimental engine test data characterized by variable EGR rates. The liquid spray-air interaction is studied within a flow field generated by the previous gas exchange process, the external ducts being included in the computational domain. This allows a more realistic evaluation of the fuel-air mixing under the actual conditions occurring at different engine regimes.