Modeling the Effect of Nozzle Hole Geometry on Diesel Injection and Combustion

The performance of the ensemble diesel engine-injection system has been investigated by modeling; different approaches have been combined and integrated in a multi step procedure. In a preliminary phase, the nozzle flow features have been investigated by means of 3D CFD simulation (FIRE), allowing for the evaluation of nozzle hole discharge coefficients. Such values have been used in the subsequent phase, based on a 0/1D approach, in which the complete model of the fuel injection system has been realized and the injected fuel amounts have been evaluated. On the basis of these indications, a further simulation phase has been included and a packet model for the modeling of fuel jet formation, evaporation and combustion has been built and used. In-cylinder pressure trends have been obtained and the effects of different nozzle hole geometries have been investigated.