Hydrodynamic Responses of a Spar-Type Floating Wind Turbine in High Waves

2014 ◽  
Vol 31 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Y-J. Lee ◽  
C.-Y. Ho ◽  
Z.-Z. Huang
Keyword(s):  
International Energy Agency ◽  
Computer Code ◽  
Experimental Results ◽  
Offshore Wind ◽  
Scale Model ◽  
Tropical Storms ◽  
Energy Agency ◽  
Deep Waters ◽  
Floating Offshore Wind Turbines ◽  
The Time Domain

AbstractFloating offshore wind turbines (FOWTs) can be used to exploit the enormous wind energy present over deep waters. Numerous studies have examined the dynamics of FOWTs, but few have focused on validating numerical results with experimental results, particularly for a deep draught FOWT in regions with frequent tropical storms. For this study, we developed a computer code and conducted experiments with a scale model to validate the simulation results. The computer code was first verified by comparing the results with those of the International Energy Agency Wind Task 23. Numerical simulations were implemented in both the frequency domain and the time domain. A comparison of the numerical and experimental results of the scale model in high waves showed good agreement. The flexibility of blades and the tower did not observably affect the motion of the deep draft spar-type FOWT. Therefore, it can be ignored in the preliminary design. The pitch motion of the scale model was within 1°. Therefore, the spar-type FOWT may be an effective power source for regions with frequent tropical storms.

scholarly journals Response of the IEA Wind 15 MW – WindCrete and Activefloat floating wind turbines to wind and second-order waves

2021 ◽  
Author(s):  
Mohammad Youssef Mahfouz ◽  
Climent Molins ◽  
Pau Trubat ◽  
Sergio Hernández ◽  
Fernando Vigara ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Reference Model ◽  
Numerical Models ◽  
International Energy Agency ◽  
Second Order ◽  
Offshore Wind ◽  
Wave Forces ◽  
Energy Agency ◽  
Floating Offshore Wind Turbines ◽  
Floating Platforms

Abstract. The EU Horizon 2020 project COREWIND has developed two floating platforms for the new International Energy Agency (IEA) Wind 15 MW reference model. One design – WindCrete – is a spar floater, and the other – Activefloat – is a semi-submersible floater. In this work the design of the floaters is introduced with their aero-hydro-servo-elastic numerical models, and the responses of both floaters in both static and dynamic simulations are verified against the operational and survival design limits. The static displacements and natural frequencies are simulated and discussed. Additionally, the effects of the mean wave drift forces, and difference second order wave forces on the systems' responses are presented. The increase in the turbine's power capacity to 15MW in IEA Wind model, leads to an increase in inertial forces and aerodynamic thrust force when compared to similar floating platforms coupled to the Danish Technical University (DTU) 10MW reference model. The goal of this work is to investigate the floaters responses at different load cases. The results in this paper suggest that at mild wave loads the motion responses of the 15MW Floating Offshore Wind Turbines (FOWT) are dominated by low frequency forces. Therefore, motions are dominated by the wind forces, and second order wave forces rather than the first order wave forces. After verifying and understanding the models' responses, the two 15MW FOWT reference numerical models are publicly available to be used in the research and development of floating wind energy.

scholarly journals Response of the International Energy Agency (IEA) Wind 15 MW WindCrete and Activefloat floating wind turbines to wind and second-order waves

2021 ◽  
Vol 6 (3) ◽  
pp. 867-883
Author(s):  
Mohammad Youssef Mahfouz ◽  
Climent Molins ◽  
Pau Trubat ◽  
Sergio Hernández ◽  
Fernando Vigara ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Numerical Models ◽  
International Energy Agency ◽  
Second Order ◽  
Offshore Wind ◽  
Wave Forces ◽  
Energy Agency ◽  
Frequency Wave ◽  
Floating Offshore Wind Turbines ◽  
Floating Platforms

Abstract. The EU Horizon 2020 project COREWIND (COst REduction and increase performance of floating WIND technology) has developed two floating platforms for the new International Energy Agency (IEA) Wind 15 MW reference wind turbine. One design – “WindCrete” – is a spar floater, and the other – “Activefloat” – is a semi-submersible floater; both designs are made of concrete. In this work the design of the floaters is introduced with their aero–hydro–servo-elastic numerical models, and the responses of both floaters in both static and dynamic simulations are investigated. The static displacements and natural frequencies are simulated and discussed. Additionally, the effects of the mean wave drift forces and second-order difference-frequency wave forces on the systems' responses are presented. The increase in the turbine's power capacity to 15 MW in IEA Wind model leads to an increase in inertial forces and aerodynamic thrust force when compared to similar floating platforms coupled to the Technical University of Denmark (DTU) 10 MW reference model. The goal of this work is to investigate the floaters' responses for different load cases. The results in this paper suggest that at mild wave loads the motion responses of the 15 MW floating offshore wind turbines (FOWTs) are dominated by low-frequency forces. Therefore, motions are dominated by the wind forces and second-order wave forces rather than the first-order wave forces. After assessing and understanding the models' responses, the two 15 MW FOWT numerical reference models are publicly available to be used in the research and development of floating wind energy.

Physical Model Testing of the TetraSpar Demo Floating Wind Turbine Prototype

2019 ◽  
Author(s):  
Michael Borg ◽  
Anthony Viselli ◽  
Christopher K. Allen ◽  
Matthew Fowler ◽  
Christoffer Sigshøj ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Numerical Models ◽  
Model Testing ◽  
Offshore Wind ◽  
Scale Model ◽  
Test Facility ◽  
Hydrodynamic Characteristics ◽  
Ocean Engineering ◽  
Floating Wind Turbine ◽  
Floating Offshore Wind Turbines

Abstract As part of the process of deploying new floating offshore wind turbines, scale model testing is carried out to de-risk and verify the design of novel foundation concepts. This paper describes the testing of a 1:43 Froude-scaled model of the TetraSpar Demo floating wind turbine prototype that shall be installed at the Metcentre test facility, Norway. The TetraSpar floating foundation concept consists of a floater tetrahedral structure comprising of braces connected together through pinned connections, and a triangular keel structure suspended below the floater by six suspension lines. A description of the experimental setup and program at the Alfond W2 Ocean Engineering Lab at University of Maine is given. The objective of the test campaign was to validate the initial design, and contribute to the development of the final demonstrator design and numerical models. The nonlinear hydrodynamic characteristics of the design are illustrated experimentally and the keel suspension system is shown to satisfy design criteria.

Aero-Elastic-Control-Floater-Mooring Coupled Dynamic Analysis of Floating Offshore Wind Turbine in Maximum Operation and Survival Conditions

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Y. H. Bae ◽  
M. H. Kim
Keyword(s):  
Dynamic Analysis ◽  
Clean Energy ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Coupled Dynamic Analysis ◽  
Floating Offshore Wind Turbines ◽  
Mooring Dynamics ◽  
Dynamics And Control ◽  
The Time Domain

Increasing numbers of floating offshore wind turbines (FOWTs) are planned in the coming years due to their high potential in the massive generation of clean energy from ocean wind. In the present study, a numerical prediction tool has been developed for the fully coupled dynamic analysis of an FOWT system in the time domain including aero-loading, tower/blade elasticity, blade-rotor dynamics and control, mooring dynamics, and platform motions so that the influence of aero-elastic-control dynamics on the hull-mooring performance and vice versa can be assessed. The Hywind spar design with a 5 MW National Renewable Energy Laboratory (NREL) turbine is selected as an example and two different collinear wind-wave-current environmental conditions, maximum operational and survival conditions, are applied for this study. The maximum operational condition means the maximum environmental condition with normal blade-turbine operation and the survival condition represents the extreme situation without any blade-turbine operation. Through this study, it is seen that the ultimate-loading environments for different structural components of the FOWT can be different. The developed technology and numerical tool are readily applicable to the design of any type of future FOWTs in any combinations of irregular waves, dynamic winds, and steady currents.

scholarly journals Nonlinear Wave Loads on Offshore Wind Turbines: Extreme Statistics and Fatigue

2019 ◽  
Author(s):  
Yu Zhang ◽  
Paul D. Sclavounos
Keyword(s):  
Nonlinear Wave ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Wave Loads ◽  
Extreme Statistics ◽  
Support Structure ◽  
Nonlinear Load ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
The Time Domain

Abstract The development is presented of an analytical model for the prediction of the stochastic nonlinear wave loads on the support structure of bottom mounted and floating offshore wind turbines. Explicit expressions are derived for the time-domain and frequency-domain nonlinear exciting forces in a seastate with significant wave height comparable to the diameter of the support structure based on the fluid impulse theory. The higher order moments of the nonlinear load are evaluated from simulated force records and the derivation of analytical expressions for the nonlinear load statistics for their efficient use in design is addressed.

Experimental Study on Flow-Induced Motions (FIM) of a Floating Offshore Wind Turbine Semi-Submersible Type (OC4 Phase II Floater)

2019 ◽  
Author(s):  
Rodolfo T. Gonçalves ◽  
Maria E. F. Chame ◽  
Leandro S. P. Silva ◽  
Arjen Koop ◽  
Shinichiro Hirabayashi ◽  
...  
Keyword(s):  
Phase Ii ◽  
Transverse Direction ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Deep Waters ◽  
New Concepts ◽  
Floating Offshore Wind Turbines ◽  
Floating System ◽  
Cable Systems

Abstract Flow-Induced Motions (FIM) is an issue for multi-column platforms, and the phenomenon can decrease the fatigue life of the mooring, riser, and cable systems. In the past, FIM was studied mainly for platforms installed in deep waters. The new concepts of Floating Offshore Wind Turbines (FOWT) have multi-column design and may therefore observe FIM. However, FOWTs have been installed in shallow water and, in this case, the FIM remains insufficiently investigated. To address this issue, FIM model tests were performed for the – Semisubmersible (SS) Floating System design developed for the DeepCwind project (OC4 Phase II). The goal of this paper is to investigate the presence of FIM for this type of system to show the importance of FIM in the design of FOWT. Three different incidence angles of the current were tested, namely 0, 90 and 180 degrees. For each heading, thirty reduced velocities were tested. The results showed amplitudes in the transverse direction of around 70% of the diameter of the platform column, which is similar to the ones observed for the deep-draft (DD) SS with circular columns and larger than for the platforms with square columns. The results showed that FIM was present for this specific FOWT SS investigated and that it may thus be essential to consider when designing the mooring system, as an increment in the total cost of the platform may make the system economically unfeasible. When extrapolating the results for the full-scale configuration, the FIM synchronization occurred for current velocities from 0.5m/s up to 1.2m/s, and the maximum nondimensional nominal amplitudes for the motions in the transverse direction reached 70% of the external column diameter.

Offshore wind energy generation has huge potential

2019 ◽  
Keyword(s):  
Wind Energy ◽  
International Energy Agency ◽  
Offshore Wind ◽  
Offshore Wind Energy ◽  
Chinese Firms ◽  
Energy Agency ◽  
Content Type ◽  
Wind Energy Generation ◽  
Cost Reductions ◽  
Order Books

Subject Offshore wind costs and potential. Significance The International Energy Agency (IEA) released a report on October 25 estimating that offshore wind capacity will rise 15-fold over the next two decades. Costs have been falling ahead of expectations and further cost reductions will help the sector to build more momentum. Impacts North European turbine producers and wind project developers see huge export potential, but Chinese firms will provide stiff competition. Offshore construction vessels will support rising offshore wind deployment and help to bolster currently weak shipyard order books. Governments and regulators will create supportive policies for offshore wind, but this will occur gradually and differently across regions.

scholarly journals Numerical Analysis of a Catenary Mooring System Attached by Clump Masses for Improving the Wave-Resistance Ability of a Spar Buoy-Type Floating Offshore Wind Turbine

2019 ◽  
Vol 9 (6) ◽  
pp. 1075 ◽  
Author(s):  
Zhenqing Liu ◽  
Yuangang Tu ◽  
Wei Wang ◽  
Guowei Qian
Keyword(s):  
Wind Turbine ◽  
International Energy Agency ◽  
Wave Resistance ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Induced Response ◽  
Mooring Lines ◽  
Energy Agency

The International Energy Agency (IEA), under the auspices of their Offshore Code Comparison Collaboration (OC3) initiative, has completed high-level design OC-3 Hywind system. In this system the wind turbine is supported by a spar buoy platform, showing good wave-resistance performance. However, there are still large values in the motion of surge degree of freedom (DOF). Addition of clump masses on the mooring lines is an effective way of reducing the surge motion. However, the optimization of the locations where the clump masses are added is still not clear. In this study, therefore, an in-house developed code is verified by comparing the results of the original OC3 model with those by FAST. The improvement of the performance of this modified platform as a function of the location of the clump masses has been examined under three regular waves and three irregular waves. In the findings of these examination, it was apparent that attaching clump masses with only one-tenth of the mass of the total mooring-line effectively reduces the wave-induced response. Moreover, there is an obvious improvement as the depth of the location where the clump masses mounted is increased.

Design and Validation of a Multi-Scale Model Floating Offshore Test Wind Turbine

2018 ◽  
Author(s):  
Jacob C. Ward ◽  
Matthew J. Fowler ◽  
Anthony M. Viselli ◽  
Andrew J. Goupee ◽  
Habib J. Dagher
Keyword(s):  
Wind Turbine ◽  
Froude Number ◽  
Wind Turbines ◽  
Complex Loading ◽  
Reynolds Numbers ◽  
Offshore Wind ◽  
Scale Model ◽  
Speed Ratio ◽  
Multi Scale ◽  
Floating Offshore Wind Turbines

A variable-scale model wind turbine has been developed by the Advanced Structures and Composites Center for testing scale-model floating offshore wind turbines. This model has been designed to be lightweight with a robust individual blade pitch mechanism. Froude number similitude is used to develop scaling relationships, while specialized blades have been designed to produce representative aerodynamic forces despite mismatched Reynolds numbers. Numerical simulations show that the model turbine is able to match the scaled aerodynamic thrust of commercial wind turbines by altering blade pitch and maintaining Froude number and tip-speed-ratio similitude. This turbine has the capability to accurately simulate commercial turbines of varying sizes in complex loading conditions with the additional capability to implement and test new control algorithms.

scholarly journals Development and Verification of an Aero-Hydro-Servo-Elastic Coupled Model of Dynamics for FOWT, Based on the MoWiT Library

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1974
Author(s):  
Mareike Leimeister ◽  
Athanasios Kolios ◽  
Maurizio Collu
Keyword(s):  
Wind Turbine ◽  
International Energy Agency ◽  
Coupled Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
System Behavior ◽  
Energy Agency ◽  
Realistic Representation ◽  
Non Linear System ◽  
Fully Coupled

The complexity of floating offshore wind turbine (FOWT) systems, with their coupled motions, aero-hydro-servo-elastic dynamics, as well as non-linear system behavior and components, makes modeling and simulation indispensable. To ensure the correct implementation of the multi-physics, the engineering models and codes have to be verified and, subsequently, validated for proving the realistic representation of the real system behavior. Within the IEA (International Energy Agency) Wind Task 23 Subtask 2 offshore code-to-code comparisons have been performed. Based on these studies, using the OC3 phase IV spar-buoy FOWT system, the Modelica for Wind Turbines (MoWiT) library, developed at Fraunhofer IWES, is verified. MoWiT is capable of fully-coupled aero-hydro-servo-elastic simulations of wind turbine systems, onshore, offshore bottom-fixed, or even offshore floating. The hierarchical programing and multibody approach in the object-oriented and equation-based modeling language Modelica have the advantage (over some other simulation tools) of component-based modeling and, hence, easily modifying the implemented system model. The code-to-code comparisons with the results from the OC3 studies show, apart from expected differences due to required assumptions in consequence of missing data and incomplete information, good agreement and, consequently, substantiate the capability of MoWiT for fully-coupled aero-hydro-servo-elastic simulations of FOWT systems.

Sign in / Sign up

Export Citation Format

Share Document