| With the continuous implementation of the concept of environmental dredging how to effectively barrier the diffusion of dredged suspended solids has become one of the problems faced by dredging operations.Bubble plume barrier technology diffusion as a new antifouling technology,now recognized its barrier formed by the principle of bubble plume of shear flow carry particles as a circular motion and realize the particles,as a matter of fact,different properties of particles under the action of shear flow dynamics behavior is not the same,except by the effect of shear flow and particles,The effect of bubbles on particles in the core region of bubble plumes also affects the barrier behavior of bubble plumes,so the principle and failure mode of bubble plumes barrier particles are not discussed from the perspective of particle dynamics.In view of this,the dynamic behavior of particles in the core region of shear flow and bubble plume is studied from the perspective of particle dynamics.The work done is as follows:Firstly,the dynamic behavior of particles in the shear flow field on both sides of the bubble plume was investigated by experimental study and coupled CFD and DEM numerical simulation based on Euler method.The particle trajectories in the shear flow field were qualitatively studied,and the effects of operating conditions,water velocity and particle properties on particle distribution characteristics were quantitatively analyzed.Secondly,aiming at the dynamic behavior of particles in the core region of bubble plume,a CFD-DEM numerical model based on THE VOF method was used to simulate the bubble rising and particle settling process in gas-liquid-solid three-phase system,and the process of bubbles acting on particles was investigated.Finally,based on the dynamic behavior of particles on both sides of the plume and the core area of the bubble plume,the diffusion principle and barrier failure mode of the bubble plume barrier particles were proposed,and the factors affecting the diffusion performance and applicability of the bubble plume barrier dredged particles were discussed.The conclusions are as follows:(1)The barrier principle of bubble plumes to particles varies with the location of particles.For the particles in the shear flow field on the left side of the bubble plume,they mainly move counterclockwise under the carrying of the shear flow,so that the particles are confined to the left side of the plume,so as to realize the separation of particles.For the particles in the core area of the plume,the particles move near the liquid surface by the push of the top of the bubble and entailed by the wake,and then return to the left side of the plume after the vortex disturbance on the left side of the bubble plume,thus achieving barrier.(2)The barrier failure mode of bubble plume varies with the quality of plume formation.When the plume quality is good,the particles move near the liquid surface by the bubbles in the core area of the bubble plume first,and then reach the right side of the plume by the vortex disturbance on the right side of the bubble,and the barrier failure occurs.In addition to the above barrier failure mode,when the plume is of poor quality,the particles pass directly through the core region of the plume from the bubble gap to the right side of the plume,resulting in barrier failure.(3)The better the plume formation quality(plume generator,ventilation flow,etc.),the weaker the ocean current intensity(flow velocity),and the more obvious the bubble plume barrier effect.The properties of particles affect the barrier effect by affecting the settlement characteristics of particles,and the larger the particle size and density,the better the barrier effect. |
