Experimental and numerical investigation on inner flow and spray characteristics of elliptical GDI injectors with large aspect ratio

Abstract

The application of non-circular elliptical orifice is recognized to increase the fuel spray and mixing quality, which has potential ability for modern gasoline direct injection (GDI) engines. In this research work, a single-hole elliptical GDI injector with aspect ratio of 4 was adopted. Numerical simulation and experimental spray test are both introduced to study the inner flow patterns and spray characteristics. The results indicated that the cavitation is mainly distributed on the minor axial plane of the elliptical GDI injector, and the cavitation domain decreases gradually with the increase of back pressure. Additionally, the unique swallowtail-like spray structure discharging from the elliptical GDI injector with aspect ratio of 4 was captured for the first time, and the swallowtail-like spray structure only appeared on the major view plane of the elliptic spray. Moreover, the GDI elliptical spray tip branching length reduced with the increase of the back pressure, and the high back pressure can inhibit the formation of swallowtail-like spray structure. Finally, the branching angle at the spray tip increased with the increase of back pressure, because high back pressure will enhance the effect of high aerodynamic force.