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Liquid atomisation is an important technical field for a wide range of engineering and industrial applications, particularly in the field of internal combustion engines. In these engines, in fact, the amount of pollutants at the engine-out interface is directly related to the quality of the combustion process, which is in turn determined by the quality of the air-fuel mixture preparation in Direct Injection (DI) engines. As a consequence numerical-experimental research is crucial to their development. Despite the significant amount of research that has been carried out on DI engines simulation, breakup modelling is still a challenge. In this paper we present a new numerical model for multiphase flows that could be particularly suited for liquid jet and droplet breakup simulation. The model is based on a Lattice Boltzmann (LB) solver coupled to a higher order finite difference treatment of the kinetic forces arising from non-ideal interactions (potential energy).

The introduction of the high-pressure fully electronic-controlled injection systems has opened a number of new possibilities to optimize diesel engine performance and to reduce pollutant emissions. However greater research efforts are required to meet future European emission legislation. The control of the combustion process, which determines to a large extent the amount of pollutant emissions, requires primarily an understanding of its physics and chemistry as well as the capability to modify one or more of the interdependent process parameters in a given direction. Since many parameters have to be considered, a combined experimental-numerical approach is required.

The first part of the paper gives an overview of the current results obtained with the first-generation of GDI-powered vehicles launched on the European market. In view of the rather limited success in fuel consumption gain the second-generation of very lean stratified layouts has begun, but this process requires the development and application of new high-level analysis tools. A possible high performance approach is the multi-purpose use of 3-D numerical simulation both in the development and the engine control strategy calibration phases. The development of a small 1.6 liter lean stratified engine project was chosen to demonstrate the dual application capability of the NCF-3D simulation tool. The paper continues with a description of the engine application frame, the basic features of the NCF-3D simulation tool and the latest enhancements made to combustion and fuel composition models within the software frame.