Study On Dynamic Response Of Marine Ranching Column Buoy Fastened By Multi-Mooring Under Wave Action

The buoy is a good carrier to realize environmental monitoring and underwater biological image monitoring of marine ranching.At present,the researches on buoys dedicated to marine ranching is still in the exploratory stage.There is a big difference between the structure of the marine ranching buoy proposed in this thesis and the traditional buoy.In order to collect water samples of different water depths for detection and analysis,it is necessary to enter the water at a large depth.At this stage,it is necessary to explore the hydrodynamic characteristics and wave action mechanism of the marine ranch buoy fastened by multi-mooring.In this thesis,the marine ranching column buoy fastened by multi-mooring was taken as the research object.Based on the programming language C++,the finite element method and the lumped mass point method were used to study the motion and force variation of the marine ranching buoy fastened by multi-mooring under wave action.At the same time,compared with the physical experiment results,the feasibility of the self-developed model was proved and the buoy structure and mooring system parameters were optimized.The main research contents and results are as follows:(1)Taking the wave conditions in the East China Sea as the prototype,the marine ranching column buoy was designed according to the model similitude criteria.The counterweight experiment,the mooring position experiment,and the mooring line length experiment were carried out in turn.The effects of them on the mooring tension and the hydrodynamic characteristics of the buoy motion such as surge,heave and roll were analyzed.The counterweight of 800 g,the mooring position of 20 cm,and the mooring line length of1.5 m were selected as the optimal working conditions.The mooring line material was discussed,and the chain was used as the better mooring material.(2)Based on the programming language C++,the finite element method and the lumped mass point method were used to establish the numerical model of the marine ranch buoy under wave action.The tension of mooring line and the motion of the tracer point in the physical model experiment were verified,and the results are in good agreement.The numerical simulation of the marine ranching buoy fastened by three or four iron chains was carried out.Considering the stability and economy,it is better to select the marine ranching buoy fastened by three iron chains.In addition,the tension of iron chains and the motion of marine ranching buoy under different wave incident angles were analyzed.It is found that the wave incident angle of 0°is better under 3 iron chains,and the incident angle of 15°and 45°is recommended for 4 iron chains.In general,the marine ranching column buoy fastened by multi-mooring is less affected by the incident direction of waves and can adapt to waves incident in different directions.(3)The results show that the wave resistance of the marine ranching buoy can be effectively improved by changing the internal weight,the mooring position,the length of the mooring line,the mooring material,the number of mooring lines and the wave incident angles.The research results and numerical simulation methods in this thesis can provide reference for the safety evaluation and stability of this kind of structure.