Spray Collapse in a Side-mount Gasoline Direct Injection Injector with Various Injection Conditions and Injector Nozzle Configurations

In this study, the spray collapse in a non-flash boiling condition was studied. Spray collapse can occur in a side-mount gasoline direct injection (GDI) injector because of its narrow hole distance. To investigate the spray collapse, a spray visualization system was constructed with a high speed camera and a metal halide lamp. Spray visualization was conducted at various injection pressures, ambient pressure, and fuel temperature conditions. Moreover, two injectors with a narrow or wide hole pattern were used to observe the effects of the nozzle hole pattern. The central spray developed by spray collapse overtook the plume jet. As the injection pressure increased, the central spray overtook the plume jet earlier; however, the distance from the nozzle tip was not related to the injection pressure. Higher ambient pressure significantly reduced to the time to overtaking by increasing the spray cone angle. Additionally, when the ambient pressure was high, the effect of fuel temperature was negligible; however, when the ambient pressure was close to or less than the fuel saturation pressure, the spray collapse was dramatically accelerated because of the high evaporation rate with flash boiling. The nozzle hole pattern also had a significant effect on the overtaking point. The narrower hole pattern promoted spray collapse by more effectively blocking air flow from the outside to inside spray, which led to changes in the spray tip penetration. However, the velocity at the plume development and central spray was nearly the same, regardless of nozzle hole pattern.