Assessment of a 3D CFD model for GDI spray impact against wall through experiments based on different optical techniques

In the present paper, a basic study is performed on gasoline sprays issuing from high pressure injectors under controlled conditions: the experimental characterization of multi-hole and single-hole GDI sprays in their impact over a plate is carried out with the aim of creating a set of data to be used for the validation of a properly developed simulation model. The multi-hole spray allows accounting for the jet-to-jet interaction and represents a condition closer to the actual gasoline supply mode in present GDI engines. The single-hole injector configuration is instead preferred for a more detailed study, as it allows capturing effects related to the role that diverse parameters characterizing the liquid droplet dynamics play during and after their impingement on heated solid surfaces. The CFD model is conceived with the scope of its future application within numerical calculations of entire engine working cycles. A highly portable free spray sub-model allows correctly reproducing the injection dynamics under different conditions in a confined vessel, while the spray-wall impingement sub-model is shown being able to highlight to an acceptable extent the gasoline splashing and deposition phenomena.