An experimental study on the flow characteristic of a swirling liquid jet in its near field

In order to verify the accuracy of theoretical prediction, an experimental system mainly consisting of an injecting system and photographing system has been established. The nozzles with swirl chambers and orifices are used to form hollow swirling liquid jets, whose parameters can be conveniently changed and measured. The effect of parameters such as flow conditions, fluid properties and nozzle geometries on the hollow swirling liquid jet shape in the near-field has been investigated. The results show that under low injection pressure conditions the sheets in space are olive-shaped hollow jets, whose velocity and sheet thickness change periodically along the nozzle axis. Increasing the injection pressure and the diameter of orifices will lead to flux increase, while decreasing the diameter or the angle of swirl chambers has the opposite influence. Nozzle geometry parameters such as orifice diameter, swirl chamber diameter, angle of swirl chamber inlet and length diameter ratio of exit orifice have an effect on the size of liquid shape. As the surface tension of the liquid reduced, the size of the liquid jet increased. The existing of pressure difference between outer and inner surface of the jet constrains the development of the jet.