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No.5 (1972/03) >

Title :球形構造物の波による振動に関する基礎的研究
Title alternative :Fundamental Study on the Vibration of a Submarine Structure Caused by Surface Waves.
Authors :河野, 二夫
Authors alternative :Kono, Tsugio
Issue Date :Mar-1972
Abstract :The hydrodynamic effects of surface waves on a submarine structure are studied theoretically and experimentally. Main results of the study are summerized as follows: a) It can be assumed that a submerged sphere is affected by the forces composed of dynamic pressure calculated by the potential theory and hydraulic resistance which is proportional to the square of the relative velocity. The equation of motion of a sphere fixed by the spring on the sea bottom is developed on the basis of the above assumption and is solved analytically by the perturbation wethod. The characteristics of vibration of a sphere due to waves are measured in the wawe tank and the results of experiments coinside fairly well with the theoretical results, which means that the above assumption is reasonable. Therefore, it can be considered that the basic equation is applicable to the analysis of the full size submarine structures. b) The transverse vibration of a sphere to the woves_is recognized by the experiments. It is understood that this phenomenon is caused by the un-symmetric separation of flow around the sphere. The frequency of vibration is either the same or twice of the wave frequency. c) By investigating the theory of vibration of two spheres, it is found that the added mass changes by the direction of the wave to a line connecting centres of spheres. When the wave direction coincides with the center line of spheres, the added mass decreases and when the wave direction is perendicular to the center line, it increases in comparison with the single sphere. d) The motion of sphere is characterized by the theoretical investigation as follows; i) the added mass is increased, and ii) the effective pressure on the sphere is decreased, as the sphere approaches to the artinode of the standing wave. These results are confirmed by the experiments. e) It is obtained by the experiments that the amplitude of the vibrations is reduced by attaching wire-ring on the sphere. Based on the above investigation, the guide for the hydraulic design of the submarine structure is provided.
Type Local :紀要論文
ISSN :0387-429X
Publisher :琉球大学理工学部
URI :http://hdl.handle.net/20.500.12000/24957
Citation :琉球大学理工学部紀要. 工学篇 = Bulletin of Science & Engineering Division, University of the Ryukyus. Engineering no.5 p.129 -212
Appears in Collections:No.5 (1972/03)

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