2003 Fiscal Year Final Research Report Summary
A Study on Dynamics of Flexible Marine Riser
| Project/Area Number |
13355037
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
海洋工学
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| Research Institution | Kyushu University |
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Principal Investigator |
KOTERAYAMA Wataru Kyushu University, Research Institute for Applied Mechanics, Professor, 応用力学研究所, 教授 (80038562)
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| Co-Investigator(Kenkyū-buntansha) |
KAJIWARA Hiroyuki Kyushu University, Graduate School of Engineering, Professor, 大学院・工学研究院, 教授 (30114862)
YAMAGUCHI Satoru Kyushu University, Graduate School of Engineering, Assoc.Professor, 大学院・工学研究院, 助教授 (00253542)
NAKAMURA Masahiko Kyushu University, Research Institute for Applied Mechanics, Assoc.Professor, 応用力学研究所, 助教授 (40155859)
WASHIO Yukihisa Japan Marine Science & Technology Center, Sub-leader, 海洋技術研究部, 副主幹
OHMATSU Shigeo National Maritime Research Institute, Director, 海洋開発研究領域, 領域部長
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| Project Period (FY) |
2001 – 2003
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| Keywords | Flexible Marine Riser / 3-D Calculation Method / Vortex Induced |
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| Research Abstract |
In this study, a numerical method is developed for analyzing the motion, shear force and moment of a riser. Firstly full nonlinear equations of motions for the riser dynamics are derived using 'Hamilton's principle' and then linearized under appropriate assumptions for convenience of the numerical work. A numerical simulation scheme for riser dynamics developed in this paper is based on the 'Galerkin method' and 'Newmark-b method'. For validating accuracy of the eveloped simulation scheme, model experiments are carried out in an experimental tank under various experimental conditions, Highly flexible riser models are used in these experiments. The top end of the riser model is forced to oscillate harmonically without wave or current. Ten to twelve CCD cameras are arranged at five to six vertical positions along the riser axis Z and at each vertical position two cameras are fixed in X-Y directions so that the three-dimensional riser motion can be measured. One camera can track three clo
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se points simultaneously and the slope of the riser model at each measured point can be detected. In each experiment, a five-component load cell is installed at the top end of the riser model to measure the force and moment exerted on the model. A comprehensive and accurate experimental system has been established.
Results of model experiments are analyzed and discussed in various aspects. By comparing the results of the inline motion in the same direction as the forced oscillation with those of numerical simulations, it is confirmed that the developed numerical simulation scheme can describe accurately the riser inline motion, force and moment except in the range of extremely strong motion. In the range of high oscillation frequency and large oscillation amplitude, the discrepancy between experiments and simulations become visible in figures, which may be attributed to the linearization of the motion equations with the assumption of small tension variation or to the effects of vortex-induced vibration. They fall on the future work to be researched further.
In the final year, the simulation method of "Vortex Induced Vibration of Marine Riser in Oscillating Flow" has been developed and its accuracy was confirmed by comparing with experiments. Less
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Research Products
(14 results)
