Multi-bubble pulsation characteristics under boundary conditions of ship structure
To study the pulsating characteristics of multiple bubbles near the wall of a ship structure,a technique involving underwater low-voltage discharge at 400 V to generate bubbles is used.The pulsating process of underwater bubbles is recorded with a high-speed camera.By placing two bubbles either horizontally or vertically beneath a horizontal wall at an appropriate distance from the wall,and symmetrically arranging two bubbles horizontally on both sides of a V-shaped wall surface,the coupled pulsating characteristics of multiple bubbles are analyzed at different distances from the wall and bubble space.Experimental results show that the coupling characteristics of two bubbles vary under different boundary conditions.When two bubbles are vertically arranged beneath a horizontal wall,neck constriction occurs after bubble fusion,leading to a jet penetrating through the bubble and impacting the wall,causing an impact force on the wall.Fusion of two bubbles arranged horizontally beneath a horizontal wall results in an obliquely upward jet,which collides and ultimately impacts the wall,causing damage.When two bubbles are horizontally arranged beneath a V-shaped wall surface,the coupling generates jets directed towards each other and the V-shaped structure.The jets collide between the bubbles,causing bubble rupture and resulting in less impact on the V-shaped structure.