Study On Dynamics Of3D Mooring Systems And Experimental Analysis

Mooring systems have the advantages of simple structure and low cost, so it iswidely used in the marine of ocean engineering. Single-Point-Mooring system iswidely used in sub-surface buoy system, Single-Point-Mooring cage system in fishing,Single-Point-Mooring in tanker mooring and so on. In this thesis, a dynamic model isfounded based on the mooring system, dynamic response of a sub-surface buoysystem during the deployment in different ocean circumstance of buoy is analyzed. Adynamic study of mooring lines in different sea conditions is also analyzed based onseaweed-cable model. For the seaweed-cable system, we studied the dynamics ofdifferent nodes, the tension response of cable rope in the seabed, all of these studies isquietly used in understanding the dynamic theory of mooring system and forecastingthe property of mooring system, it will provide a theoretical foundation for safeworking of buoy system.A polygon approximation method based on lumped mass has been applied tostudy the dynamics of the mooring system. Considering the hydrodynamics ofdifferent nodes and the elastic property of lines, we made a dynamic model formooring system in time domain. In this model, we analyzed the motion of every node,the posture of whole system and the tension response of cable.A numerical simulation of sub-surface buoy system was made during thedeployment procedure, we got the velocity profile of every nodes and the trajectoryduring the buoy deployment in three-dimensional area through numerical simulation.In order to testify the accuracy of the simulation result, we designed a four-nodesub-surface buoy model, and made an experiment in the transparent pool in the lab.According to the comparison, a conclusion is got that the simulation result is fit wellwith the experiment result.Based on lumped-mass-method, we assume that every seaweed as a node, adynamic and posture analysis is made based on seaweed-cable model under the excitation of waves and currents. A50-year return period severe weather circumstanceis simulated, we studied the dynamic response of the seaweed-cable system in thesevere weather condition. The simulation of seaweed cable depth information is quiteuseful for seaweed absorbing enough sunshine and enough nutrition, and it is alsouseful for seaweed getting suitable water layer. The seaweed-cable simulationsupplies a theoretical support for seaweed artificial breeding.