A5102750814- Wave and Wind Energy Systems
- Wind and Air Flow Studies
- Fluid Dynamics and Vibration Analysis
- Wind Energy Research and Development
- Structural Engineering and Vibration Analysis
- Vibration and Dynamic Analysis
- Structural Health Monitoring Techniques
- Structural Behavior of Reinforced Concrete
- Fluid Dynamics and Turbulent Flows
- Concrete Corrosion and Durability
- Meteorological Phenomena and Simulations
- Fluid Dynamics Simulations and Interactions
- Dynamics and Control of Mechanical Systems
- Real-time simulation and control systems
- Vehicle Noise and Vibration Control
- Aeolian processes and effects
- Mechanical Failure Analysis and Simulation
- Structural Analysis and Optimization
- Modeling and Simulation Systems
- Mechanical Engineering and Vibrations Research
- Metallurgy and Material Forming
- Mechanical stress and fatigue analysis
- Ship Hydrodynamics and Maneuverability
- Magnetic Bearings and Levitation Dynamics
- Electric Motor Design and Analysis
DNV (Norway)
2024
ClassNK
2016-2023
The University of Tokyo
2011-2017
Renewable Energy Systems (United States)
2017
This paper summarizes the findings from Phase II of Offshore Code Comparison, Collaboration, Continued, with Correlation project. The project is run under International Energy Agency Wind Research Task 30, and focused on validating tools used for modeling offshore wind systems through comparison simulated responses select system designs to physical test data. Validation activities such as these lead improvement tools, which will enable development more innovative cost-effective designs. For...
Abstract Phase I of the OC6 project is focused on examining why offshore wind design tools underpredict response (loads/motion) OC5-DeepCwind semisubmersible at its surge and pitch natural frequencies. Previous investigations showed that underprediction was primarily related to nonlinear hydrodynamic loading, so two new validation campaigns were performed separately examine different load components. In this paper, we validate a variety against test data, focusing ability accurately model...
Currently, the design of floating offshore wind systems is primarily based on mid-fidelity models with empirical drag forces. The tuning model coefficients requires data from either experiments or high-fidelity simulations. As part OC6 (Offshore Code Comparison Collaboration, Continued, Correlation, and unCertainty (OC6) a project under International Energy Agency Wind Task 30 framework) project, present investigation explores latter option. A verification validation study computational...
The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project, is validation aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison simulated results to response data physical systems. Phase III OC5 project analyzes Senvion 5M turbine supported by OWEC Quattropod from alpha ventus farm. This paper shows verification OWT models (code-to-code comparison). A subsequent publication will focus on their...
Three models with different footing types were used to clarify the effect of heave plates on hydrodynamic behavior elastic response a flexible multicolumn floating offshore wind turbine (FOWT). The tested under regular waves, whose added mass, damping, and motion results compared numerical simulations by NK-UTWind WAMIT codes. As whole, attachment was responsible for increasing mass damping levels, consequently modifying RAO models. Regarding in sea condition, decrease 33% 66% significant...
Abstract While the structural damping is an important parameter in seismic resistant design, several problems exist current design codes such as that recommended values vary largely between codes, and second mode ratio which required usually not described. In order to evaluate ratios for both first modes of MW‐size wind turbines, a series excitation tests using active mass damper were performed this study on 2.4 MW offshore turbine. First, sinusoidal test, gives accurate reliable results...
A tank experiment using a flexible multi-column floating offshore wind turbine (FOWT) model in regular waves was carried out to clarify the floater elastic response and its influence on motion. The motion from compared with numerical simulations by NK-UTWind WAMIT codes. dynamic deformation of also between NK-UTWind. observed significant for decks columns around wave period corresponding natural structural vibration. Furthermore, comparing heave amplitude operator (RAO) experiments...
Abstract The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project is validation aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison simulated results to response data physical systems. Phase III OC5 validates OWT models against measurements recorded on a Senvion 5M turbine supported by OWEC Quattropod from alpha ventus farm. following operating conditions were chosen validation: (1) Idling below...
Floating Offshore Wind Turbines (FOWTs) are subject to combined wind and wave loads. The response is not given as a simple sum of the wind-only wave-only due nonlinear coupling effects, which makes structural analysis more complex time-consuming. When spectral approach for fatigue considered, it necessary accurately estimate variance stress taking account effect. In this study, firstly characteristics investigated. It found out effects two-fold; one aerodynamic exciting load increase forced...
Abstract In the design of supporting platforms floating offshore wind turbines, global response analysis is essential to predict under various loads from wave, wind, moorings and turbines. However, literature turbines combining flexible modelling platform potential flow theory for hydrodynamic evaluation limited. this study, framework implementing hydrodynamics time-domain three-dimensional frame model was developed using modal decomposition evaluations. The method utilized assumption that...
Abstract Prestressed concrete is gaining growing interests as an alternative to steels for the construction material floating platforms of wind turbines due its low costs. Investigation characteristics structure under fluctuating loadings are necessary ensure structural integrity, where a reference model both platform and accompanying design highly useful. In this study, prestressed-concrete spar-type floater 10 MW designed together with structure. Frequency-domain analysis showed that...
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Adequate design methods for concrete offshore wind turbines need to be determined through investigations on the characteristics of dynamic responses and structural behavior. For these future studies, a reference semi-submersible floater 10 MW turbine was designed in this study along with associated cross-sections members. A assessment carried out ultimate, fatigue, serviceability limit states. Six cases combinations loading conditions requirements were assumed watertightness, as required...
Abstract Prestressed concrete floaters are gaining growing interest for floating wind turbines, while different material properties can affect the characteristics of floater motions and range suitable geometries. In this study, a basic geometry semi-submersible 10MW is designed, based on which sensitivity study property design conducted. It was found that minimum pitch angles achieved by selecting optimum geometries were similar three types material, larger values geometrical variables...
Coupled aero-hydro-servo-elastic simulation tools play an important role in the design of offshore floating wind turbines. For rational system, accuracy numerical tool is predicting system responses. While load cases where and wave are aligned sometimes largest contributor to design, evaluation a misaligned condition also required codes. In this study, first series water tank tests performed for 1/50 scale semisubmersible floater results irregular with were analysed. Then, in-house tool,...
The dynamic loadings of the wind turbine main shafts are important for drivetrain components as external excitation force, and evaluation their dependence on characteristics is necessary both understanding bahavior extrapolation at different sites. In this study, load measurements were performed along with field measurement. Next multivariate regression analysis was utilized to identify influential parameters that affect statistics shaft. Finally, identified evaluated qualitatively using...
Accurate prediction of the secondary moment three-dimensional turbulent wind field is important for structure dynamic analysis, while literatures on turbulence scales offshore are limited. In this study, an measurement campaign carried out by meteorological mast using ultrasonic anemometers at 40, 60 and 80m heights, from which integral length used in von Karman model evaluated. It found that these heights can be expressed well model. The evaluated fitting auto-spectrum spatial coherence....
Floating cranes are often used for the installation and maintenance operations offshore wind turbines when they located in deep waters. As motions of vessel being easily affected by external environments, accurate prediction motion system is important. In this study, first a numerical based on basic multibody dynamics developed estimation behaviour lifting using floating cranes. Next, on-site measurements carried out operation caisson crane. Two models were built with flexible fixed...
The effect of watertightness criteria on structural assessment was investigated in this study through the design a semi-submersible floater for 10 MW wind turbine. A carried out ultimate, fatigue, and serviceability limit states, where six cases combinations loading conditions requirements were assumed watertightness. different resulted designs prestressing tension, which also caused differences margins ultimate states as well SN diagram used fatigue states. maximum stress acting member...
Accurate estimation of structural parameters such as the natural frequencies, modal shapes and damping ratios is important for both numerical modelling health monitoring, ambient vibration analysis usually used estimation. Although Eigensystem Realization Algorithm (ERA) widely used, results are known to depend on selection calculation parameters. In this study, first sensitivity NExT-ERA method full-scale measurement data a 2,4MW wind turbine studied provide reference practical application...
浮体式洋上風車は安全性の向上とコスト低減のため動的応答解析の精度向上が必要である．本論文では 流体力モデルとしてポテンシャル論およびモリソン式を使用して弾性体としてモデル化したセミサブ型浮 体の解析を行い得られた動的応答について両モデルの比較を行った．モリソン式，ポテンシャル論で計算