Experimental investigation on the spray characteristic of air-assisted hollow-cone gasoline injector

•We, for the first time, studied air-assisted spray undergoing flash boiling.•Decreasing of ambient pressure results in the internal flash boiling.•Increasing of fuel temperature results in the external flash boiling.•Droplet velocity and SMD are dominated by pa and injection durations. Spray characteristics of an air-assisted hollow-cone gasoline injector were investigated experimentally. Spray shadowgraph images were taken by a high-speed camera, while droplet size and velocity at measurement point were measured by a Phase Doppler Particle Analyzer (PDPA) system. The results show that, decreasing of ambient pressure results in the internal flash boiling and increasing of fuel temperature results in the external flash boiling. Two flash boiling regimes show significantly different characteristics in spray shape and width. Droplet mean velocity was found to decrease with ambient pressure, fuel temperature and fuel injection duration increasing; while SMD was found to increase with ambient pressure and fuel injection duration increasing but decrease with fuel temperature increasing. The gap period between fuel injection and fuel/air mixture injection shows insignificant influence on the spray characteristic of air-assisted hollow-cone gasoline injector.