Development of a Turbulence-induced Breakup Model for Gasoline Spray Simulation

The design and optimization of a modern spray-guided gasoline direct injection engine require a thorough understanding of the fuel spray characteristics and atomization process. The fuel spray Computational Fluid Dynamics (CFD) modeling technology can be an effective means to study and predict spray characteristics, and as a consequence, to drastically reduce experimental work during the engine development process. For this reason, an accurate numerical simulation of the spray evolution process is imperative. Different models based on aerodynamically-induced breakup mechanism have been implemented to simulate spray atomization process in earlier studies, and the effect of turbulence from the injector nozzle is recently being concerned increasingly by engine researchers.

In this study, a turbulence-induced primary breakup model coupled with aerodynamic instability is developed. A competition between the turbulence-induced and aerodynamic-induced breakup mechanisms is carried out to determine the dominant primary breakup mechanism for a droplet parcel. This model improves the simulation accuracy by employing a new droplet generation mechanism based on the research that the droplet formation is mainly linked to ligament evolution during the turbulent breakup process. The new model is validated with the high-speed imaging and Phase Doppler Particle Analyzer (PDPA) experiments, and the simulation result shows a good agreement with the experiment data.