Development of a Scaled-Down Floating Wind Turbine for Offshore Basin Testing

2014 ◽  
Author(s):  
Erik-Jan de Ridder ◽  
William Otto ◽  
Gert-Jan Zondervan ◽  
Fons Huijs ◽  
Guilherme Vaz
Keyword(s):  
Wind Turbine ◽  
Wind Velocity ◽  
Scaling Laws ◽  
Scale Effects ◽  
Model Testing ◽  
Model Tests ◽  
Full Scale ◽  
Pitch Control ◽  
Model Scale ◽  
Floating Wind Turbine

In the last years MARIN has been involved in an increasing number of projects for the offshore wind industry. New techniques in model testing and numerical simulations have been developed in this field. In this paper the development of a scaled-down wind turbine operating on a floating offshore platform, similar to the well-known 5MW NREL wind turbine is discussed. To simulate the response of a floating wind turbine correctly it is important that the environmental loads due to wind, waves and current are in line with full scale. For dynamic similarity on model scale, Froude scaling laws are used successfully in the Offshore industry for the underwater loads. To be consistent with the underwater loads, the winds loads have to be scaled according to Froude as well. Previous model tests described by Robertson et al [1] showed that a geometrically-scaled turbine generated a lower thrust and power coefficient with a Froude-scaled wind velocity due to the strong Reynolds scale effects on the flow. To improve future model testing, a new scaling method for the wind turbine blades was developed originally by University of Maine, and here improved and applied. In this methodology, the objective is to obtain power and thrust coefficients which are similar to the full-scale turbine in Froude-scaled wind. This is obtained by changing the geometry of the blades in order to provide thrust equality between model and full scale, and can therefore be considered as a “performance scaling”. This method was then used to design and construct a new MARIN Stock Wind Turbine (MSWT) based on the NREL 5MW wind turbine blade, including an active blade pitch control to simulate different blade pitch control systems. MARIN’s high-quality wind setup in combination with the new model scale stock wind turbine was used for testing the GustoMSC Tri-Floater semi-submersible as presented in Figure 1, including an ECN active blade pitch control algorithm. From the model tests it was concluded that the measured thrust versus wind velocity characteristics of the new MSWT were in line with the full scale prediction and with CFD (Computational Fluid Dynamics) results.

Development of a Scaled Rotor Blade for Tank Tests of Floating Wind Turbine Systems

2018 ◽  
Author(s):  
Paul Schünemann ◽  
Timo Zwisele ◽  
Frank Adam ◽  
Uwe Ritschel
Keyword(s):  
Wind Turbine ◽  
Rotor Blade ◽  
Turbine Rotor ◽  
Full Scale ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Model Scale ◽  
Floating Wind Turbine ◽  
Hydrodynamic Effects ◽  
Wind Turbine Rotor

Floating wind turbine systems will play an important role for a sustainable energy supply in the future. The dynamic behavior of such systems is governed by strong couplings of aerodynamic, structural mechanic and hydrodynamic effects. To examine these effects scaled tank tests are an inevitable part of the design process of floating wind turbine systems. Normally Froude scaling is used in tank tests. However, using Froude scaling also for the wind turbine rotor will lead to wrong aerodynamic loads compared to the full-scale turbine. Therefore the paper provides a detailed description of designing a modified scaled rotor blade mitigating this problem. Thereby a focus is set on preserving the tip speed ratio of the full scale turbine, keeping the thrust force behavior of the full scale rotor also in model scale and additionally maintaining the power coefficient between full scale and model scale. This is achieved by completely redesigning the original blade using a different airfoil. All steps of this redesign process are explained using the example of the generic DOWEC 6MW wind turbine. Calculations of aerodynamic coefficients are done with the software tools XFoil and AirfoilPrep and the resulting thrust and power coefficients are obtained by running several simulations with the software AeroDyn.

Methodology for Wind/Wave Basin Testing of Floating Offshore Wind Turbines

2012 ◽  
Author(s):  
Heather R. Martin ◽  
Richard W. Kimball ◽  
Anthony M. Viselli ◽  
Andrew J. Goupee
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Model Testing ◽  
Full Scale ◽  
Scale Model ◽  
Horizontal Axis Wind Turbine ◽  
Wind Turbine Aerodynamics ◽  
Floating Wind Turbine ◽  
Floating Offshore Wind Turbines ◽  
Wave Basin

Scale model wave basin testing is often employed in the development and validation of large scale offshore vessels and structures by the oil and gas, military and marine industries. A basin model test requires less time, resources and risk than a full scale test while providing real and accurate data for model validation. As the development of floating wind turbine technology progresses in order to capture the vast deepwater wind energy resource, it is clear that model testing will be essential for the economical and efficient advancement of this technology. However, the scale model testing of floating wind turbines requires one to accurately simulate the wind and wave environments, structural flexibility and wind turbine aerodynamics, and thus requires a comprehensive scaling methodology. This paper presents a unified methodology for Froude scale testing of floating wind turbines under combined wind and wave loading. First, an overview of the scaling relationships employed for the environment, floater and wind turbine are presented. Afterward, a discussion is presented concerning suggested methods for manufacturing a high-quality, low turbulence Froude scale wind environment in a wave basin to facilitate simultaneous application of wind and waves to the model. Subsequently, the difficulties of scaling the highly Reynolds number-dependent wind turbine aerodynamics is presented in addition to methods for tailoring the turbine and wind characteristics to best emulate the full scale condition. Lastly, the scaling methodology is demonstrated using results from 1/50th scale floating wind turbine testing performed at MARIN’s (Maritime Research Institute Netherlands) Offshore Basin which tested the 126 m rotor diameter NREL (National Renewable Energy Lab) horizontal axis wind turbine atop three floating platforms: a tension-leg platform, a spar-buoy and a semi-submersible. The results demonstrate the methodology’s ability to adequately simulate full scale global response of floating wind turbine systems.

Influence of the Rotor Characterization on the Motion of a Floating Wind Turbine

2015 ◽  
Author(s):  
Sébastien Gueydon ◽  
Guillaume Venet ◽  
Gerson Fernandes
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Rotation Speed ◽  
Model Tests ◽  
Full Scale ◽  
Aerodynamic Damping ◽  
Common Solution ◽  
Floating Wind Turbine ◽  
Wave Basin ◽  
Low Reynolds

It is useful to complement model tests of a floating wind turbine with simulations mimicking the scaled-down turbine. Standard engineering tools have some short-comings to model a rotor at the very low Reynolds that Froude scaled wind and rotor’s rotation speed impose. The flow around an airfoil at the scale of a wave basin brings new distinct challenges than at full scale. The capacity of standard engineering tools for the design of wind turbines to capture this complexity may be questioned. Therefore, work-around solutions need to be proposed. This paper looks at a common solution that consists of optimizing the load coefficients of the rotor to reproduce the measured rotor loads. 3 variants of optimizations are applied to a semisubmersible floating wind turbine at scale 1/50th, the DeepCwind semisubmersible platform. The effects of the differences between these 3 methods on the motions of the floater in waves and wind are analyzed. In the absence of a controller for the rotor, no significant differences related to the induced aerodynamic damping was noticed, but an offset in the motion related to a thrust deficit was observed.

Methodology for Wind/Wave Basin Testing of Floating Offshore Wind Turbines

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Heather R. Martin ◽  
Richard W. Kimball ◽  
Anthony M. Viselli ◽  
Andrew J. Goupee
Keyword(s):  
Wind Turbine ◽  
Model Test ◽  
Wind Turbines ◽  
Model Testing ◽  
Full Scale ◽  
Scale Model ◽  
Horizontal Axis Wind Turbine ◽  
Wind Turbine Aerodynamics ◽  
Floating Wind Turbine ◽  
Wave Basin

Scale-model wave basin testing is often employed in the development and validation of large-scale offshore vessels and structures by the oil and gas, military, and marine industries. A basin-model test requires less time, resources, and risk than a full-scale test, while providing real and accurate data for numerical simulator validation. As the development of floating wind turbine technology progresses in order to capture the vast deep-water wind energy resource, it is clear that model testing will be essential for the economical and efficient advancement of this technology. However, the scale model testing of floating wind turbines requires accurate simulation of the wind and wave environments, structural flexibility, and wind turbine aerodynamics and thus requires a comprehensive scaling methodology. This paper presents a unified methodology for Froude scale model testing of floating wind turbines under combined wind and wave loading. First, an overview of the scaling relationships employed for the environment, floater, and wind turbine are presented. Afterward, a discussion is presented concerning suggested methods for manufacturing a high-quality, low-turbulence Froude scale wind environment in a wave basin to facilitate simultaneous application of wind and waves to the model. Subsequently, the difficulties of scaling the highly Reynolds number–dependent wind turbine aerodynamics is presented in addition to methods for tailoring the turbine and wind characteristics to best emulate the full-scale condition. Lastly, the scaling methodology is demonstrated using results from 1/50th-scale floating wind turbine testing performed at the Maritime Research Institute Netherlands (MARIN) Offshore Basin. The model test campaign investigated the response of the 126 -m rotor diameter National Renewable Energy Lab (NREL) horizontal axis wind turbine atop three floating platforms: a tension-leg platform, a spar-buoy, and a semisubmersible. The results highlight the methodology's strengths and weaknesses for simulating full-scale global response of floating wind turbine systems.

scholarly journals The Triple Spar campaign: Model tests of a 10MW floating wind turbine with waves, wind and pitch control

2017 ◽  
Vol 137 ◽  
pp. 58-76 ◽  
Author(s):  
H. Bredmose ◽  
F. Lemmer ◽  
M. Borg ◽  
A. Pegalajar-Jurado ◽  
R.F. Mikkelsen ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Model Tests ◽  
Pitch Control ◽  
Floating Wind Turbine

Coupled Dynamics of a Vertical Axis Wind Turbine (VAWT) With Active Blade Pitch Control on a Semi-Submersible Floater

2018 ◽  
Author(s):  
Ebert Vlasveld ◽  
Fons Huijs ◽  
Feike Savenije ◽  
Benoît Paillard
Keyword(s):  
Wind Turbine ◽  
Wind Velocity ◽  
Vertical Axis ◽  
Power Production ◽  
Mooring Line ◽  
Vertical Axis Wind Turbine ◽  
Coupled Dynamics ◽  
Low Frequencies ◽  
Pitch Control ◽  
Thrust And Torque

A vertical axis wind turbine (VAWT) typically has a low position of the center of gravity and a large allowable tilt angle, which could allow for a relatively small floating support structure. Normally however, the drawback of large loads on the VAWT rotor during parked survival conditions limits the extent to which the floater size can be reduced. If active blade pitch control is applied to the VAWT, this drawback can be mitigated and the benefits can be fully utilized. The coupled dynamics of a 6 MW VAWT with active blade pitch control supported by a GustoMSC Tri-Floater semi-submersible floater have been simulated using coupled aero-hydro-servo-elastic software. The applied blade pitch control during power production results in a steady-state thrust curve which is more comparable to a HAWT, with the maximum thrust occurring at rated wind velocity. During power production, floater motions occur predominantly at low frequencies. These low frequency motions are caused by variations in the wind velocity and consequently the rotor thrust and torque. For the parked survival condition, it is illustrated that active blade pitch control can be used to effectively reduce dynamic load variations on the rotor and minimize floater motions and mooring line tensions.

Model Tests of a Spar-Type Floating Wind Turbine Under Wind/Wave Loads

2015 ◽  
Author(s):  
Fei Duan ◽  
Zhiqiang Hu ◽  
Jin Wang
Keyword(s):  
Wind Turbine ◽  
Model Test ◽  
Wind Wave ◽  
Wave Model ◽  
Offshore Structures ◽  
Model Tests ◽  
Wave Loads ◽  
Scaled Model ◽  
Floating Wind Turbine ◽  
Wave Effects

Wind power has great potential because of its clean and renewable production compared to the traditional power. Most of the present researches for floating wind turbine rely on the hydro-aero-elastic-servo simulation codes and have not been exhaustively validated yet. Thus, model tests are needed and make sense for its high credibility to master the kinetic characters of floating offshore structures. The characters of kinetic responses of the spar-type wind turbine are investigated through model test research technique. This paper describes the methodology for wind/wave model test that carried out at Deepwater Offshore Basin in Shanghai Jiao Tong University at a scale of 1:50. A Spar-type floater was selected to support the wind turbine in this test and the model blade was geometrically scaled down from the original NREL 5 MW reference wind turbine blade. The detail of the scaled model of wind turbine and the floating supporter, the test set-up configuration, the mooring system, the high-quality wind generator that can create required homogeneous and low turbulence wind, and the instrumentations to capture loads, accelerations and 6 DOF motions are described in detail, respectively. The isolated wind/wave effects and the integrated wind-wave effects on the floating wind turbine are analyzed, according to the test results.

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.

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