Hydrodynamic Phenomenon and Its Effects in Large Scale Floating Structures

点击翻译按钮获取中文摘要

In this study, first of all, the accuracy of the analysis method of wave load, which has been developed in the laboratory of the head investigator, was discussed by comparison with experiments of a model of semisubmersible with a large number of columns connected by lower hulls. An interesting phenomenon of generation of standing wave was found out in the numerical simulation by the above analysis method and confirmed by the experiments in the case where the incident wave has some particular direction and frequency for the model composed of densely allocated large number columns with large diameter.In the case of large scale semisubmersibles, the rigidity with respect to deformation in the vertical direction is, generally speaking, much smaller than that in the horizontal direction. Therefore, an analysis method for vertical elastic deformation including rigid motion was developed by combining the 3D-matrix method with the wave load analysis method mentioned above and the high accuracy was confirmed by comparison with experiments of a model. It can be said from the results obtained that hydroelasticity should be taken into account in the case of large scale semisubmersible with a large number of column elements.On the other hand, regarding wind, an experimental study on wind load was carried out. Using the wind tunnel for full span model test belonging to the department of Civil Engineering of the University of Tokyo, element-wise drag and lift foyces of a model of a large scale semisubmersible were measured. Especially, in some cases, combination models of the semisubmersible structure and a solid wave surface with high wave height were used to measure the effect of existence of waves on wind loads. The results showed that the wind load is not so small and may be considerably large especially, in the case of combined model mentioned above.Therefore, it is considered to be important to study further the effect of wind on behaviors of large scale semisubmersibles.