Abstract
To explore the reason for the bubble sweep-down phenomenon of research vessels and its effect on the position of the stern sonar of a research vessel, the use of a fairing was investigated as a defoaming appendage. The separation vortex turbulence model was selected for simulation, and the coupled Eulerian-Lagrangian method was adopted to study the characteristics of the bubble sweep-down motion, captured using a discrete element model. The interaction between the bubbles, water, air, and hull was defined via a multiphase interaction method. The bubble point position and bubble layer were calculated separately. The spatial movement characteristics of the bubbles were extracted from bubble trajectories. It was demonstrated that the bubble sweep-down phenomenon is closely related to the distribution of the bow pressure field and that the bubble motion characteristics is related to the speed and initial bubble position. When the initial bubble position is between the water surface and the ship bottom, the impact on the middle of the ship bottom is greater and increases further with increasing speed. A deflector forces the bubbles to both sides through physical shielding, strengthening the local vortex structure and keeping bubbles away from the middle of the ship bottom.
Highlights
Exploring and understanding the ocean are prerequisites for the development of marine resources and the protection of the marine ecological environment
3) The movement characteristics of the bubble sweep-down space are related to the initial position and speed of the bubble
When the bow is closer to the bottom of the ship, the sweeping position of the bubble is closer to the bow, and the position after the bottom of the ship is closer to the center line of the bottom of the ship
Summary
Exploring and understanding the ocean are prerequisites for the development of marine resources and the protection of the marine ecological environment. The marine research vessel is a type of ship extremely suitable for this. The research vessel is dedicated to scientific investigations of the sea, with the purpose of obtaining comprehensive marine geology, biology, and ecology survey information of the atmosphere, for example. Karafiath [1] analyzed the occurrence of the phenomenon of bubble sweep-down and believed that, under actual sea conditions, owing to the strong fluidity of seawater, strong sea breeze, and the effects of wave breaking and rainwater impact, the seawater near the water surface has a certain air content, within a certain water depth range. A layer of suspended bubbles is formed in this water layer
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