Experimental and numerical study on the formation and detachment of bubbles at orifices under the impinging jet flow

Three detachment patterns, i.e. single bubble pattern, double bubble pattern, atomizing pattern, are observed as the jet velocity increases. The bubble formation and detachment model are established, and the intensification mechanisms of the impinging jet on the bubble formation and detachment is revealed: Instantaneous flow field fluctuations changes the direction of the pressure difference force, forcing the bubble to detach and shortening the bubble growth time. The fluctuations of the flow field cause the total force on the bubble in the radial direction to be non-zero and the displacement of the bubble in the radial direction appears, which reduces the axial drag and the resistance of bubble to leave the orifice. In summary, under the effect of the impinging jet, the growth time of the bubble is shortened and the detachment size is reduced, which provides the possibility of producing small bubbles through large-diameter holes.