Numerical Simulation Of Flow Field Motion Characteristics Around Bubble Curtain

With the development of society and economy,the state and the people have improved the environmental protection requirements,and the new non-polluting bubble curtain device has been widely applied and developed,such as submarine noise isolation,different gravity flow protection,and anti-fine particles in river and lake water dredging projects.Diffusion,etc.At present,domestic and foreign scholars pay more attention to the characteristics of bubble curtains,such as bubble diameter,rising speed,aspect ratio,separation and polymerization of bubbles,etc.,but the research on the influence of bubble curtain on surrounding flow field is relatively Less,so the research on the flow field around the bubble curtain can increase the understanding of the bubble curtain,expand its engineering application value,and provide a basis for practical engineering applications.In this paper,the numerical simulation of single-hole outflow bubble and bubble curtain is carried out by using VOF interface tracking technology and k-? turbulence model based on OpenFOAM open source program.Firstly,based on the basic theory,experimental research and numerical simulation of single bubble and bubble curtain.The mathematical model of bubble calculation and the initial and boundary conditions required for calculation are established.The computational fluid dynamics method is used to study the dynamic behaviors such as the formation,detachment,rise and trajectory of single-hole outflow bubbles in gas-liquid two-phase flow.Based on the research,a mathematical model of the bubble curtain of porous openings was established,and the flow field distribution around the bubble curtain was studied.The results show that in the study of bubble motion characteristics,as the diameter of the orifice and the inlet velocity of the orifice increase,the bubble detachment time gradually decreases,the detachment diameter gradually increases,and the bubble detachment diameter gradually increases;The trajectory of bubble rising motion has a great influence.The trajectory of the rising air bubble of the continuous air supply is basically the same as that of the air supply.The rising motion trajectory of the initial spherical bubble is different from the former two.The surrounding streamline is basically in the process of rising the initial bubble.Symmetrical distribution,the bubble is less than the axis,The distribution of the flow line around the continuous supply and interruption of the air supply is more complicated,and the bubble is more off-axis;in the simulation of the bubble flow field,the speed of the instantaneous axis on the bubble before the water exits is the horizontal axis of the calculation domain is approximately axisymmetric.The larger the inlet velocity and the orifice diameter,the larger the combined velocity.The dimensionless analysis of the final velocity of the bubble gives the prediction formula of the final velocity of the bubble.In the bubble curtain simulation,as the inlet velocity of the orifice,the diameter of the orifice,and the number of orifices increase,the fluid can be transported.The moving speed is increased,so that more surrounding water movement can be driven;the surrounding flow field moving speed driven by the bubble rising motion is mainly concentrated in the z(vertical)direction,and the speeds in the x and y directions are relatively small;the main speed of the fluid movement is concentrated.In the upper side of the vertical orifice;in addition,the movement direction of the water body driven by the upward movement of the bubble is basically upward,and the bottom water body forms a circulation flow from both sides after reaching the water surface;by analyzing the distribution law of the velocity of the section,The prediction formula of the velocity of the cross-section of the bubble curtain based on the Gaussian distribution is fitted.