Spray Characterization of a Slinger Injector Using a High-Speed Imaging Technique

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This paper presents the experimental-visualization results of liquid breakup in a slinger injector with high-aspect-ratio radial–axial discharge channels over a range of rotational speeds between 600 and 10,000 rpm to identify detailed breakup pattern and spray characteristics. High-speed images of the jet breakup are captured and processed by a shadowgraph method. The particle/droplet imaging analysis technique is used to obtain the droplet-size distribution. Centripetal/Coriolis-induced stream-mode injection is observed for high-aspect-ratio axially canted discharge channels. The results show that the liquid-breakup process with rotational-speed values up to 4000 rpm corresponds to a subcritical stream-mode breakup. Moreover, a new phenomenon of jet bifurcation is observed at higher rotational speeds (more than 5000 rpm). Liquid-film disintegration is observed at rotational speeds of 10,000 rpm, which constitutes a transitional regime from subcritical to supercritical stream-mode breakup. The results show that the Sauter mean diameter decreases with increasing rotational speed. Furthermore, based on experimental observations, it is concluded that the number of injection orifices and their partitioning in different orientations affect the Sauter-mean-diameter values. Finally, a correlation is obtained between Sauter mean diameter, rotational speed, and volume-flow rate.