Development of a multipurpose auxiliary vessel for offshore wind farm installation

• Main Authors: Huang, Guan-Jie, 黃冠傑
• Other Authors: Kehr, Young-Zehr
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/t2z3au

碩士 === 國立臺灣海洋大學 === 系統工程暨造船學系 === 107 === This study is to propose a method to enhance operation capability of a Jack up type offshore wind-farm installation unit in high sea. This method is to place a moored vessel ahead of a wind-farm installation unit to induce wave shielding effect, which helps to reduce motion response of the unit and enhance its operation capability of wind-farm installation. ANSYS AQWA is utilized to analyze hydrodynamic interaction between the vessel and the wind-farm installation unit to examine the wave shielding effect. Pitch and heave motion RAOs (Response Amplitude Operator) of the installation unit with or without the vessel placing ahead are compared to evaluate the wave shielding effect for different wave incident angles and wave periods. In addition, a range of variation of breadth and draft of the vessel are included in this study for optimization of principal dimensions based on the induced wave shielding effect. The vessel is also proposed multipurpose to accommodate workers on board as a hotel at sea. This design consideration enables workers to live closely to the installation unit, which can be very beneficial on cost saving to a wind-farm project by supporting 24 hours shifting working schedule, reducing hotel necessity on shore, and omitting routine commuting between shore and the installation. Based on the wave data in the wind-farm zone offshore of the Taichung Harbor, the most common waves in that zone are waves of period 6~7 second. From the results of the study, it is observed that the vessel with draft of 12.5 meter and greater is more effective to induce wave shielding effect, which helps to reduce the pitch and heave motion RAOs of the installation unit to 1/3 or less in the waves of period 6~7 second. The deeper the draft of the vessel, the more wave shielding effect, and the more motion reduction to the installation unit. It is also observed that breadth variation of the vessel has small effect on its motion response at wave angle of 0~30 and period of 6~7 second. However, if the draft of the vessel increased, its motion response is reduced at wave angle of 0~30 and period of 6~7 seconds. Hence, the multipurpose vessel with deeper draft and narrower breadth can be designed to accommodate workers living comfortably on board and provide needed wave shielding effect to the installation unit in the wind-farm zone offshore of Taichung Harbor.