Penetration and scale low for a GDI swirled spray and its surrounding air pattern

Abstract A hollow cone spray produced by a GDI swirled injector was studied at different ambient air pressure, to investigate its shape by means of high speed photography, and its surrounding air pattern by laser Doppler velocimetry. The images show the spray initial hollow cone structure that collapses inwardly to form a narrower full cone spray, at a distance which is function of the air pressure. The air surrounding the spray tip is pushed ahead by the spray, then recirculates to be entrained by the spray body, forming a toroidal head vortex. The penetration of the spray and of the toroidal vortex scale with the air pressure with very similar laws, so that a unique scale law can be used to describe and predict the spray and vortex location and structure in a wide range of ambient pressure.