Bubble growth in water vortex unit and its effect on suction force

The vortex unit is a non-contact negative pressure generating mechanism. It blows high-pressure fluid tangentially into a cylindrical chamber through several nozzles to form a swirling flow and relies on the centrifugal inertial effect of the swirling flow to generate negative pressure and suction force. To date, all related studies and applications have used compressed air as the working fluid. Because the density of water is much greater than that of air, in this study, water was used as the working fluid to greatly improve the centrifugal inertial effect of the swirling flow. Based on this innovative idea, the swirling flow of the vortex unit with water as the working fluid was investigated through experiments. A convergence-growth-stabilization phenomenon of bubbles was discovered, and the effect of the converged central bubble on the central pressure and suction force was elucidated. The mechanism of the gap height and flow rate on the converged central bubble and suction force was also studied. The reason for the formation of the converged central bubble is that the negative pressure causes the gas to evolve out of the water, and the dispersed tiny bubbles move to the center of the vortex chamber under the influence of centrifugal inertia to form a large bubble. This study provides new research directions and usages of the vortex unit and provides important basic knowledge for further research.