Study On The Motion And Controlling Of The Spontaneous Bubble Free-Rising Based On Tail

Due to the limitations of the operating environment,the acquisition of marine instrument signals and their real-time transmission are difficult.Although the installation of long-distance instrument cables can solve this problem,the cost will increase exponentially,and the monitoring position of the instruments will also be limited.The tail equipped with sensors with different performances can follow the spontaneous motion of the bubble to reach the designated location in the ocean to complete the task of signal transmission and reception and realize intelligent control.In addition,tail-induced bubbles can spontaneously complete long-distance lateral migration,which has extremely important engineering value and scientific significance in the fields of separators,bubble columns,and plastic recycling.A rectangular hinged tail with a superhydrophobic adhesion zone is proposed to realize the spontaneous directional transport of millimeter-scale bubbles driven by buoyancy.Using the high-speed shadow imaging system,the effects of different aspect ratiosλand elevation anglesθof the tail on the bubble free rising motion and control based on tail induction were studied.According to the different aspect ratioλand elevation angleθ,the plane bubble movement trajectory is divided into four different regions:linear region,forward spiral region,zigzag region,and reverse spiral region.Among them,the"straight-line area"covers the largest range in the partition diagram,and the movement of the bubble will cause a large lateral migration.Under the same tail aspect ratio,there are two trends in the trajectory inclination angleα:the first is that with the increase of the elevation angleθ,the trajectory inclination angleαwill first decrease and then increase;the second is that with the elevation angleθincreases,the track inclinationαalso increases.In the same working condition of the elevation angle,as the aspect ratio increases,the span range of the trajectory inclination angleαis also larger.It is worth noting that when the elevation angleθ=150°,the trajectory inclination angleα＝90°,the trajectory inclination angle is not affected by the elevation angleθand the bubble size D_eq.Using the particle image velocimetry,the vortex structure of the tail-induced bubble rising motion wake was studied.The flow direction velocity field and vorticity of the bubble trail vortex are simultaneously affected by the aspect ratioλof the tail and the elevation angleθ.In the case of a larger aspect ratio and a reduced elevation angle,there are four obvious vortices in the flow direction vorticity field which forming two vortex pairs;and when the tail ratio is large,the inclination angle of the bubble trajectory increases,and the vortices in the wake gradually weaken and disappear.However,the spanwise velocity field and vorticity of the bubble movement are hardly affected by the aspect ratioλand the elevation angleθof the tail,there is no spanwise vortex in the spanwise flow field.