Characteristics of Nonevaporating Free Sprays of a High-Pressure Swirl Injector under Various Ambient and Injection Pressures

The characteristics of a nonevaporating free spray of a high-pressure swirl injector in a gasoline
direct injection (GDI) engine under various ambient and injection conditions are investigated.
The fuel spray with a hollow-cone structure, widespreading and large spray angle is observed
under injection conditions simulating the GDI engine operation at full load. The study shows
that a vortex structure can be clearly demonstrated in the spray tip region. Meanwhile, an initial
spray slug also appeared at the tip of the main spray. Under the injection conditions of GDI
engine at partial load, the structure of the fuel spray changes into a more compact and solid-cone shape spray with decreased width. Moreover, the influence of the injection pressures and
ambient pressures on the spray characteristics is investigated. Furthermore, an empirical
correlation for the tip penetration of the main spray is obtained, expressed as L = 0.027(ΔP/ρa)0.25t0.5. Good agreement in spray penetration between calculated and measured is reached to
a certain extent.