半潛式浮式風機拖航過程模擬

Abstract

本研究分析以駁船型、圓柱型和圓碟型平台搭載SNL 13.2 MW風機的半潛式浮式風機的拖航性能。為了考慮壓艙條件對拖航性能的影響，因此針對三種不同排水量進行研究。本研究假設波浪、風和海流方向一致，波高範圍介於0.5至4.5 m。使用AQWA及STAR-CCM+預測水動力特性，接著利用OrcaFlex預測繫纜受力及風機氣動力，並求解運動方程式以獲得浮式風機在新竹近海區域的海氣象條件的拖航運動響應。在拖航速度5節的條件下，分析拖航過程中的穩定性、最大傾斜角和機艙加速度是否符合相關設計準則，以及纜繩張力的要求。計算結果顯示：平台的穩定性和初始定傾高度符合相關設計準則；較大的排水量通常會減少浮式風機的傾斜角，但會增加拖纜張力；在新竹海域最常見的海況下，當示性波高與零上切週期分別為0.5 m與4.5 s時，駁船型、圓柱型和圓碟型浮台的最大傾斜角分別為0.94° 、1.58° 以及3.72° ，L2 纜繩的最大張力分別為1.20 MN、2.51 MN以及2.60 MN，表示駁船型平台在拖航過程中較為穩定以及安全。浮式風機機艙位置的加速度在多數海況條件下皆符合設計準則，但圓柱型平台的加速度值接近規範上限，顯示可能有損壞風險。

This study attempts to predict the towing performance of semi-submersible floating offshore wind turbines (FOWT). The research involves the design and analysis of three types of floating platforms: barge-type, column-type, and disk-type, all equipped with the SNL 13.2 MW wind turbine. The displacement of the FOWTs is considered to account for three ballast conditions. The hydrodynamic properties are predicted with AQWA and STAR-CCM+, followed by the prediction of towline forces and wind turbine aerodynamics utilizing OrcaFlex. The equations of motion are solved by OrcaFlex to obtain the motion response. Assuming the wave, wind, and current directions are aligned, the metocean conditions at the Hsinchu offshore area are considered, the wave height range from 0.5 m to 4.5 m. The study ensured compliance with stability, maximum inclination angle, and acceleration at the nacelle, and towline tension adhering to relevant standards, with a towing speed of 5 knots. Results revealed that the stability and initial metacentric height satisfying the relevant design criteria. Larger displacement generally reduces the tilt angle but increases towline tension. Under the most common sea conditions, when significant wave height and zero-crossing period are 0.5 m and 4.5 s, respectively, the maximum tilt angles for the barge-type, column-type, and disk-type FOWTs are 0.94°, 1.58°, and 3.72°, respectively; the maximum tension of towline L2 is 1.20 MN, 2.51 MN, and 2.60 MN, respectively. The prediction indicates that the barge-type FOWT is stable and safe during towing process. The acceleration at the nacelle generally met recommended standards, but the value for the column-type FOWT is reaching the upper limits, indicating possible potential risks of nacelle damage.