Study On Hydrodynamic Numerical Simulation And Vibration Reduction Of Test Model Of A Very Large Floating Structure

With the rapid progress of marine science and technology,it is possible for mankind to move into the deep sea and utilize marine resources.Coastal countries and regions have shifted the competitive vision of national strategic interests to marine resources.In the face of this situation,the concept of very large floating structures(VLFS)has emerged,and has become one of the hottest research directions in the field of ocean engineering.VLFS have the advantages of short construction cycle,low construction cost,removable,small environmental impact,etc.It has multifunction.The construction of VLFS is the embodiment of the country's comprehensive national strength and has far-reaching influence on regional economy,politics,military and other aspects.However,there are still some key problems in VLFS that have not been solved,and there are still difficulties in large-scale applications.Therefore,it is necessary to study VLFS.Based on the numerical simulation of a model experiment of VLFS,the hydrodynamic response parameters of the model are analyzed and compared with the experimental result.On this basis,the research on other hydrodynamic and motion responses of VLFS model is further expanded.What's more,the schemes of suppressing the heave motion are put forward,and relevant research is conducted.First of all,based on SESAM,three floating structure models with different type ends are established.The wet surface model,structure model and mass model of the structures are obtained by finite element method,and the bending moment and displacement of three models are imported into the hydrodynamic computing module.The effect of the end on its bending moment and displacement is compared and analyzed accordingly.Later,the corresponding comparison and analysis were carried out with the original experimental data.and the reliability of numerical simulation is verified.Secondly,by aid of the hydrodynamic analysis module,further hydrodynamic and motion response of the rectangular end of floating structure are analyzed,including added mass,radiation damping,first-order wave force and second-order steady drift force for different depths,and first-order wave force and second-order steady drift force for different incident angles,as well as the amplitude response in different directions of motion.The change rules of dynamic response parameters under different water depths and wave incident angles are thus be summarized.Finally,based on the demand for vibration reduction in VLFS,the heave plates are added to the model,under the two end floating boxes.The effects of the heave inhibition of the heave plates are researched and compared with by changing the depth,area size,thickness and arrangement form of them,and the factors that affect the effect of heave plates are found.The influence of heave plates structure on DOF of roll and pitch of the model is calculated,and the feasibility of heave plate to the vibration reduction in large floating structures is analyzed.