Mooring Failure Analysis of Semisubmersible Floating Offshore Wind Turbines Considering Mooring Redundancy at Each Azimuth Angle

Semisubmersible floating structures are becoming the predominant understructure type for floating offshore wind turbines (FOWTs) worldwide. As FOWTs are erected far away from land and in deep seas, they inevitably suffer violent and complicated sea conditions, including extreme waves and winds. Moor...

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Main Authors: Shuai Hao, Xuning Zhang, Yang Yu, Bin Wang, Xingdao Bo
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Journal of Marine Science and Engineering
Subjects:
Online Access:https://www.mdpi.com/2077-1312/13/2/360
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author Shuai Hao
Xuning Zhang
Yang Yu
Bin Wang
Xingdao Bo
author_facet Shuai Hao
Xuning Zhang
Yang Yu
Bin Wang
Xingdao Bo
author_sort Shuai Hao
collection DOAJ
description Semisubmersible floating structures are becoming the predominant understructure type for floating offshore wind turbines (FOWTs) worldwide. As FOWTs are erected far away from land and in deep seas, they inevitably suffer violent and complicated sea conditions, including extreme waves and winds. Mooring lines are the representative flexible members of the whole structure and are likely to incur damage due to years of impact, corrosion, or fatigue. To improve mooring redundancy at each azimuth angle around a wind turbine, a group of mooring lines are configured in the same direction instead of just one mooring line. This study focuses on the mooring failure problems that would probably occur in a realistic redundant mooring system of a semisubmersible FOWT, and the worst residual mooring layout is considered. An FOWT numerical model with a 3 × 3 mooring system is established in terms of 3D potential flow and BEM (blade element momentum) theories, and aero-hydro floating-body mooring coupled analyses are performed to discuss the subsequent time histories of dynamic responses after different types of mooring failure. As under extreme failure conditions, the final horizontal offsets of the structure and the layout of the residual mooring system are evaluated under still water, design, and extreme environmental conditions. The results show that the transient tension in up-wave mooring lines can reach more than 12,000 kN under extreme environmental conditions, inducing further failure of the whole chain group. Then, a deflection angle of 60° may occur on the residual laid chain, which may bring about dangerous anchor dragging.
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series Journal of Marine Science and Engineering
spelling doaj-art-48cacf42844044d5a549ee938ea68f902025-08-20T03:12:02ZengMDPI AGJournal of Marine Science and Engineering2077-13122025-02-0113236010.3390/jmse13020360Mooring Failure Analysis of Semisubmersible Floating Offshore Wind Turbines Considering Mooring Redundancy at Each Azimuth AngleShuai Hao0Xuning Zhang1Yang Yu2Bin Wang3Xingdao Bo4Maritime College, Tianjin University of Technology, Tianjin 300384, ChinaMaritime College, Tianjin University of Technology, Tianjin 300384, ChinaState Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation, Tianjin University, Tianjin 300072, ChinaInstitute of Ocean Energy and Intelligent Construction, Tianjin University of Technology, Tianjin 300384, ChinaMaritime College, Tianjin University of Technology, Tianjin 300384, ChinaSemisubmersible floating structures are becoming the predominant understructure type for floating offshore wind turbines (FOWTs) worldwide. As FOWTs are erected far away from land and in deep seas, they inevitably suffer violent and complicated sea conditions, including extreme waves and winds. Mooring lines are the representative flexible members of the whole structure and are likely to incur damage due to years of impact, corrosion, or fatigue. To improve mooring redundancy at each azimuth angle around a wind turbine, a group of mooring lines are configured in the same direction instead of just one mooring line. This study focuses on the mooring failure problems that would probably occur in a realistic redundant mooring system of a semisubmersible FOWT, and the worst residual mooring layout is considered. An FOWT numerical model with a 3 × 3 mooring system is established in terms of 3D potential flow and BEM (blade element momentum) theories, and aero-hydro floating-body mooring coupled analyses are performed to discuss the subsequent time histories of dynamic responses after different types of mooring failure. As under extreme failure conditions, the final horizontal offsets of the structure and the layout of the residual mooring system are evaluated under still water, design, and extreme environmental conditions. The results show that the transient tension in up-wave mooring lines can reach more than 12,000 kN under extreme environmental conditions, inducing further failure of the whole chain group. Then, a deflection angle of 60° may occur on the residual laid chain, which may bring about dangerous anchor dragging.https://www.mdpi.com/2077-1312/13/2/360mooring failuresemisubmersible FOWTmooring redundancytransient dynamic responseaero-elastic structural responseaero-hydro floating-body mooring coupled analysis
spellingShingle Shuai Hao
Xuning Zhang
Yang Yu
Bin Wang
Xingdao Bo
Mooring Failure Analysis of Semisubmersible Floating Offshore Wind Turbines Considering Mooring Redundancy at Each Azimuth Angle
Journal of Marine Science and Engineering
mooring failure
semisubmersible FOWT
mooring redundancy
transient dynamic response
aero-elastic structural response
aero-hydro floating-body mooring coupled analysis
title Mooring Failure Analysis of Semisubmersible Floating Offshore Wind Turbines Considering Mooring Redundancy at Each Azimuth Angle
title_full Mooring Failure Analysis of Semisubmersible Floating Offshore Wind Turbines Considering Mooring Redundancy at Each Azimuth Angle
title_fullStr Mooring Failure Analysis of Semisubmersible Floating Offshore Wind Turbines Considering Mooring Redundancy at Each Azimuth Angle
title_full_unstemmed Mooring Failure Analysis of Semisubmersible Floating Offshore Wind Turbines Considering Mooring Redundancy at Each Azimuth Angle
title_short Mooring Failure Analysis of Semisubmersible Floating Offshore Wind Turbines Considering Mooring Redundancy at Each Azimuth Angle
title_sort mooring failure analysis of semisubmersible floating offshore wind turbines considering mooring redundancy at each azimuth angle
topic mooring failure
semisubmersible FOWT
mooring redundancy
transient dynamic response
aero-elastic structural response
aero-hydro floating-body mooring coupled analysis
url https://www.mdpi.com/2077-1312/13/2/360
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