2010 Fiscal Year Final Research Report

A Study of the Effects that Change the Vibration Mode of Riser VIV

Research Project

Project/Area Number	21760673
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Single-year Grants
Research Field	Naval and maritime engineering
Research Institution	National Maritime Research Institute
Principal Investigator	FUJIWARA Tomo National Maritime Research Institute, 海洋開発系, 研究員 (70511591)
Project Period (FY)	2009 – 2010
Keywords	海洋工学 / 資源開発工学 / 海洋資源 / VIV(渦励振) / ライザー / 水槽試験
Research Abstract	To clarify the phenomena of dynamic variation of the riser's vibration mode, a large-scale experiment using a long model was carried out. In order to investigate an influence of the change of vibration mode on the riser VIV motion, a series of experiments were conducted with the periodic variation of top tension. VIV amplitude under dynamic tension variation is smaller than that under static condition. Additionally reduction of amplitude in case of relatively long mode-transition period is larger than that with short period. It is speculated that vibration of riser model is small because vibration mode shifted before VIV with certain mode is fully-developed.

(2 results)