Investigating Effects of Turbine-Like Blades on GDI Spray Formation, Injector Deposits and Particulate Emissions

This study investigates effects of a novel GDI injector outer tip design on the airflow behavior, spray formation, injector deposits and engine particulate emissions. The novel design has turbine-like blades that are located on the tip of the injector. The effects of turbine-like blades on the airflow behavior below the injector tip is initially investigated by means of numerical simulations with three simulation parameters: airflow velocity, air wall shear stress and prehole wetting. Simulations show that turbine-like blades increase the airflow velocity within the boundary layer. Consequently, wall shear stress increase over the injector tip. Therefore, the average prehole wetting decreases. Spray measurements show that the air entrainment increases and spray penetration reduces due to blades, which also confirm the increased airflow velocity. According to engine experiments, particulate emissions reduce slightly at high engine loads. Turbine-like blades do not cause a decrease on particulate emissions from low-to-mid engine loads. The deposit formation reduces around preholes and at the outer side of the injector tip. However, deposits cannot be avoided over the dome of the injector tip.