Experimental Study on Influence of Structural Parameters on Flow Field of Liquid-Liquid Coaxial Swirl Injector

In order to provide an efficient and reliable form of propellant spray for a liquid oxygen/methane engine, a variety structural of liquid-liquid coaxial swirl injectors were designed. A high-speed camera was used to capture the flow field. The swirling flow direction of the two-stage injector, the retracted length, the diameter of the first nozzle and the number of the two-stage tangential holes on the spray flow field were studied. The results showed that the spraying flow field characteristic of the liquid-liquid coaxial swirl injector was essentially determined by the interaction between the two liquid films. The same rotation direction could ensure a large atomization cone angle, but the opposite rotation direction would make the droplet mix more uniform. With the increase of the retracted length and diameter of the first injector, the atomization cone angle decreased gradually, whereas the mixing effect increased. As the retracted length and nozzle diameter of first injector extended, the atomization cone angle decreased but the mixing effect was enhanced. The mixing effect enhanced as the number of primary tangential holes extended and the number of secondary tangential holes declined, while the number of tangential holes scarcely affected the atomization cone angle.