Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Design and Verification of Hydraulic Cradle for Three-Floating-Body Wind Turbine Platform
Junlai Li1, Yonghe Xie2*, Yu Wei2, Yu Shu2
School of Transportation, Wuhan University of Technology.
Wuhan, Hubei, ,P.R.China
School of Naval Architecture and Maritime, ZheJiang Ocean University.
Zhoushan, Zhejiang, P.R.China

wind turbines, as a necessary technical means to develop deep offshore
wind energy, have become an important research goal of offshore windenergy utilization. Compared with traditional fixed wind turbine
platforms, floating wind turbines tend to experience harsher external
environment and load, and their motion responses are more difficult topredict. Therefore, the research on the dynamic response of floating
offshore wind turbine platforms is also a hot and difficult issue in thecurrent wind energy field (Yu et al., 2015; Yue et al., 2020). Due to thehuge cost and time of ocean tests, physical model tests and computer
numerical simulations are usually used to study the dynamic response offloating wind turbines before actual ocean tests.
With the rapid development of computer numerical simulation
technology, the dynamic response analysis of floating wind turbines inwaves can get faster and more accurate results. Wang et al. (2012) used
the open source OpenFOAM tool combined with the arbitrary gridinterface (AMI) method to numerically simulate the wind turbine bladetower interaction, and used the AMI method to handle the grid motion.
The detailed numerical results of the vortex structure, thrust time history,and pressure distribution on the blades and towers are obtained. Jeon etal. (2013) used numerical simulation methods to study the dynamic
response of a spar-type hollow cylindrical floating substructure mooredby three catenary cables to irregular wave excitation. The interaction
between the wave floating substructure and the wave-mooring cable issimulated by coupling the boundary element method and the finite
element method in a staggered iterative manner. Muliawan et al. (2013)used numerical simulation methods to study the motion behavior of a
combination of Spar-type floating wind turbines and an axi-symmetrictwo-body Wave energy converters, and estimated the power generation
conditions of floating wind turbine and Wave energy converter underoperation. Verma et al. (2019) used a numerical simulation method tostudy the impact of a lifting blade with its leading edge impacts thetower. Using Abaqus/Explicit, a comprehensive damage assessment of
the blade was conducted, and impact dynamics and energy evolution
were investigated. Sethuraman et al. (2013) used numerical simulation
methods to study the hydrodynamic response of floating wind turbines
under regular and irregular waves. The surge, heave and pitch motionsof floating wind turbines in various wave conditions are obtained .
Physical model testing is a very effective method, which is regarded as

ABSTRACTThe floating wind turbine platform will have violent oscillatory motion
under bad sea conditions, which will affect the aerodynamic
characteristics of the tower, especially the wind turbine blades. How touse the dynamic boundary method to simulate the oscillatory motion of
the floating wind turbine platform in waves is a subject worthy of study.
Firstly, in this paper, the heave, pitch and surge motions of the offshore
floating wind turbine platform are taken as the key points of dynamic
boundary design, and an experimental hydraulic cradle with elastic fixedend and elastic mount was designed. Then, the consistency of motion
characteristics of floating wind turbine blades between hydraulic cradle
and FAST numerical simulation is analyzed and verified. Finally, theresearch results show that the hydraulic cradle composed of elastic fixedend and elastic mount can effectively simulate the oscillatory motion of
the floating wind turbine platform in waves, which laid a foundation forthe subsequent experimental research on the aerodynamic characteristicsof floating wind turbine platform.

KEY WORDS: Floating wind turbine platform; dynamic
boundary theory; hydraulic cradle; dynamic response; design andvalidation.
INTRODUCTIONWind energy is a clean renewable energy, which has become the focusof energy development in the world, and is also an important support for
China to achieve the goal of "carbon neutrality" (Shi et al., 2021; Chenget al., 2021). The available offshore wind energy in the eastern coastal
area of China reaches 750 million KW, which has huge resource
potential and good market environment. At present, the development andutilization of offshore wind energy resources in shallow seas is gradually
becoming saturated. When the water depth is greater than 60m, theconstruction and maintenance costs of fixed offshore wind turbines rise
sharply, and its safety is also difficult to be guaranteed. Therefore,
offshore wind turbines are gradually developing from shallow seas todeep seas (Goupee et al., 2014; Farrugia et al., 2016). Floating offshore

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