Effects of gasoline and ethanol on inner flows and swallowtail-like spray behaviors of elliptical GDI injector

Alternative fuels have significant effects on the nozzle inner flow and spray behaviors. The present research works focus on the gasoline and ethanol impact the inner flow and spray behaviors with elliptical GDI injector. The inner flow patterns were performed with numerical modeling method, while the spray characteristics were measured by high-speed shadowgraph technique. Results indicated that the cavitation intensity of ethanol is smaller than that of gasoline, while the mass flow rate of ethanol is higher than gasoline. Also, the gasoline is giving more turbulence vortex structures in the minor axis direction of elliptical GDI injector and higher vorticity magnitude at nozzle exit compared to ethanol. The nozzle exit velocity for gasoline is consistent higher than ethanol. Additionally, the unique swallowtail-like spray structure discharging from elliptical GDI injector for gasoline only appeared in the major view plane. However, this unique spray structure did not appear in the spray tip with ethanol. Finally, gasoline spray tip penetration and spray cone angle are larger than that of ethanol spray, and the spray tip branching angle increased with the increase of back pressure for gasoline spray.