Numerical study on in-cylinder blending by means of a simultaneous direct injection of two liquid fuels in a heavy duty compression ignition engine

摘要

Dual fuel combustion has been recently of high interest, mainly in terms of utilization of fuels different than diesel fuel in compression ignition engines. Depending on the properties of a fuel which is additional to diesel fuel, and the type of the additional fuel supply method the combustion process may be strongly modified comparing to single fuel combustion. Nowadays the modification of the combustion process becomes the reason for implementing the dual fuelling process. However, still the main reason for its implementation remains the utilization of nonconventional fuels in compression ignition engines. Among different types of dual fuel systems the one based on simultaneous direct injection of two fuels seems to be most flexible one. It allows to stratify the charge in the cylinder, blend two different fuels at any ratio and does not decrease volumetric efficiency. Therefore, this study aims at mixture formation in a heavy duty engine employing simultaneous direct injection of two different liquid fuels. Special attention was paid to spray breakup and simultaneous evaporation of two fuels which are the key processes in mixture formation.