Large Eddy Simulation of GDI Single-hole and Multi-hole Injector Sprays with Comparison of Numerical Break-up Models and Coefficients

In the present study the fuel spray of a gasoline direct injected engine with multi-hole injector is simulated. Simulation inputs data, injection flow rate and spray cone angle are obtained from previous experimental studies. Log-normal distribution with different standard deviation is used for initial droplet size as the primary break-up model in order to reach the agreement between experimental and calculated spray tip penetration. As the first step, only one plume of spray injected into a quiescent air environment is simulated and validated by varying break-up model and standard deviation. Then, with coefficient obtained from the single jet simulation all six spray jets are simulated based on the injector nozzles geometry. The comparison between single-jet simulation and multi-jet simulation shows that validated model coefficients for the single-jet spray cannot be used for multi-jet spray simulation without significant modifications due to adjacent jet interaction and pressure drag. A set of new coefficients for the multi-jet spray is presented.