Trajectory deviation of target jet of air-assisted spray under different conditions

Abstract

Spray characteristics of an air-assisted Direct Injection (DI) injector were studied experimentally by employing high-speed imaging techniques and Phase Doppler Particle Analyzer (PDPA), with particularly interest in the trajectory deviation of target jet. Radial expansion in the near field was observed near the nozzle exit under flash boiling conditions, which can be achieved by decreasing the ambient pressure. The radial expansion in the far field results from the sudden depressurization induce the drastic bubble blast, which improves spray spread and enhances droplet breakup hence influences droplet velocity and size. The radial expansion in the far field, which can be observed in either elevated ambient pressures or low injection pressure conditions, occurs in the far field and results from the interaction of downward and upward gas flow therefore forced the spray plumes outwards. Increasing of the ambient temperature decreases liquid viscosity, leading to the deviation in jet trajectory occurs at the margin of the jet due to the increased vaporization of liquid fuel droplets.