Model Tests for Three Floating Wind Turbine Concepts

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.

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

Volume 9A: Ocean Renewable Energy ◽

10.1115/omae2014-23441 ◽

2014 ◽

Cited By ~ 9

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.

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

Volume 9: Ocean Renewable Energy ◽

10.1115/omae2015-42154 ◽

2015 ◽

Cited By ~ 2

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.

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Model Tests for a Floating Wind Turbine on Three Different Floaters

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4024711 ◽

2014 ◽

Vol 136 (2) ◽

Cited By ~ 54

Author(s):

Bonjun J. Koo ◽

Andrew J. Goupee ◽

Richard W. Kimball ◽

Kostas F. Lambrakos

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Wind Farms ◽

Model Tests ◽

Experimental Comparison ◽

Floating Platform ◽

Scaled Model ◽

Advantages And Disadvantages ◽

Floating Wind Turbine ◽

Floating Platforms

Wind energy is a promising alternate energy resource. However, the on-land wind farms are limited by space, noise, and visual pollution and, therefore, many countries build wind farms near the shore. Until now, most offshore wind farms have been built in relatively shallow water (less than 30 m) with fixed tower type wind turbines. Recently, several countries have planned to move wind farms to deep water offshore locations to find stronger and steadier wind fields as compared to near shore locations. For the wind farms in deeper water, floating platforms have been proposed to support the wind turbine. The model tests described in this paper were performed at MARIN (maritime research institute netherlands) with a model setup corresponding to a 1:50 Froude scaling. The wind turbine was a scaled model of the national renewable energy lab (NREL) 5 MW horizontal axis reference wind turbine supported by three different generic floating platforms: a spar, a semisubmersible, and a tension-leg platform (TLP). The wave environment used in the tests is representative of the offshore in the state of Maine. In order to capture coupling between the floating platform and the wind turbine, the 1st bending mode of the turbine tower was also modeled. The main purpose of the model tests was to generate data on coupled motions and loads between the three floating platforms and the same wind turbine for the operational, design, and survival seas states. The data are to be used for the calibration and improvement of the existing design analysis and performance numerical codes. An additional objective of the model tests was to establish the advantages and disadvantages among the three floating platform concepts on the basis of the test data. The paper gives details of the scaled model wind turbine and floating platforms, the setup configurations, and the instrumentation to measure motions, accelerations, and loads along with the wind turbine rpm, torque, and thrust for the three floating wind turbines. The data and data analysis results are discussed in the work of Goupee et al. (2012, “Experimental Comparison of Three Floating Wind Turbine Concepts,” OMAE 2012-83645).

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Model Test Data Correlations With Fully Coupled Hull/Mooring Analysis for a Floating Wind Turbine on a Semi-Submersible Platform

Volume 9B: Ocean Renewable Energy ◽

10.1115/omae2014-24254 ◽

2014 ◽

Cited By ~ 7

Author(s):

Bonjun Koo ◽

Andrew J. Goupee ◽

Kostas Lambrakos ◽

Ho-Joon Lim

Keyword(s):

Wind Turbine ◽

Model Test ◽

Model Tests ◽

Test Results ◽

Scaled Model ◽

Floating Wind Turbine ◽

Mooring Dynamics ◽

Set Up ◽

Fully Coupled ◽

Turbine Model

The DeepCwind floating wind turbine model tests were performed at MARIN (Maritime Research Institute Netherlands) with a model set-up corresponding to a 1:50 Froude scaling. In the model tests, the wind turbine was a scaled model of the National Renewable Energy Lab (NREL) 5MW, horizontal axis reference wind turbine supported by three different generic floating platforms: a spar, a semi-submersible and a tension-leg platform (TLP) (Ref. [1] and [2]). This paper presents validation of the MLTSIM-FAST [3] code with DeepCwind semi-submersible wind turbine model test results. In this integrated program, the turbine tower and rotor dynamics are simulated by the subroutines of FAST [4], and the hydrodynamic loads and mooring system dynamics are simulated by the subroutines of MLTSIM. In this study, fully coupled hull/mooring dynamics and second-order difference-frequency response are included in MLTSIM-FAST. The analysis results are systematically compared with model test results and show good agreement.

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Monitoring blade loads for a floating wind turbine in wave basin model tests using Fiber Bragg Grating sensors: A feasibility study

Marine Structures ◽

10.1016/j.marstruc.2020.102729 ◽

2020 ◽

Vol 71 ◽

pp. 102729 ◽

Cited By ~ 3

Author(s):

Binrong Wen ◽

Xinliang Tian ◽

Zhihao Jiang ◽

Zhanwei Li ◽

Xingjian Dong ◽

...

Keyword(s):

Wind Turbine ◽

Fiber Bragg Grating ◽

Feasibility Study ◽

Model Tests ◽

Bragg Grating ◽

Fiber Bragg Grating Sensors ◽

Floating Wind Turbine ◽

Wave Basin ◽

Blade Loads

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Real-Time Hybrid Model Testing of a Semi-Submersible 10MW Floating Wind Turbine and Advances in the Test Method

ASME 2018 1st International Offshore Wind Technical Conference ◽

10.1115/iowtc2018-1081 ◽

2018 ◽

Cited By ~ 2

Author(s):

Maxime Thys ◽

Valentin Chabaud ◽

Thomas Sauder ◽

Lene Eliassen ◽

Lars O. Sæther ◽

...

Keyword(s):

Wind Turbine ◽

Real Time ◽

Physical Model ◽

Hybrid Model ◽

Parallel Robot ◽

Ocean Basin ◽

Model Tests ◽

Test Method ◽

Load Application ◽

Floating Wind Turbine

This article presents the Real-Time Hybrid Model (ReaTHM®) tests that were performed on a 10-MW semi-submersible floating wind turbine in the Ocean Basin at SINTEF Ocean in March 2018. The ReaTHM test method was used for the model tests to circumvent the limitations encountered when performing model tests with wind and waves. The physical model was subject to physical waves, while the rotor and tower loads were simulated in real-time and applied on the model by use of a cable-driven parallel robot. Recent advances in the ReaTHM test method allowed for extended testing possibilities and load application up to the 3p frequency and the first tower bending frequency.

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Blade loading performance of a floating wind turbine in wave basin model tests

Ocean Engineering ◽

10.1016/j.oceaneng.2020.107061 ◽

2020 ◽

Vol 199 ◽

pp. 107061 ◽

Cited By ~ 1

Author(s):

Binrong Wen ◽

Zhanwei Li ◽

Zhihao Jiang ◽

Xinliang Tian ◽

Xingjian Dong ◽

...

Keyword(s):

Wind Turbine ◽

Model Tests ◽

Blade Loading ◽

Floating Wind Turbine ◽

Wave Basin

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UNAFLOW: a holistic experiment about the aerodynamics of ﬂoating wind turbines under imposed surge motion

10.5194/wes-2021-12 ◽

2021 ◽

Author(s):

Alessandro Fontanella ◽

Ilmas Bayati ◽

Robert Mikkelsen ◽

Marco Belloli ◽

Alberto Zasso

Keyword(s):

Wind Tunnel ◽

Wind Turbine ◽

Wind Turbines ◽

Unsteady Aerodynamics ◽

Model Tests ◽

Tip Vortex ◽

Scale Model ◽

Floating Wind Turbine ◽

Floating Offshore Wind Turbines ◽

Sectional Model

Abstract. Floating offshore wind turbines are subjected to large motions because of the additional degrees of freedom offered by the floating foundation. The rotor operates in highly dynamic inflow conditions and this is deemed to have a significant effect on the aerodynamic loads, as well as on the wind turbine wake. Floating wind turbines and floating farms are designed by means of numerical tools, that have to model these unsteady aerodynamic phenomena to be predictive of reality. Experiments are needed to get a deeper understanding of the unsteady aerodynamics, and hence leverage this knowledge to develop better models, as well as to produce data for the validation and calibration of the existing tools. This paper presents a wind-tunnel scale-model experiment about the unsteady aerodynamics of floating wind turbines that followed a radically different approach than the other existing experiments. The experiment covered any aspect of the problem in a coherent and structured manner, that allowed to produce a low-uncertainty data for the validation of numerical model. The data covers the unsteady aerodynamics of the floating wind turbine in terms of blade forces, rotor forces and wake. 2D sectional model tests were carried to study the aerodynamics of a low-Reynolds blade profile subjected to a harmonic variation of the angle of attack. The lift coefficient shows an hysteresis cycle that extends in the linear region and grows in strength for higher motion frequencies. The knowledge gained in 2D sectional model tests was exploited to design the rotor of a 1/75 scale model of the DTU 10MW that was used to perform imposed surge motion tests in a wind tunnel. The tower-top forces were measured for several combinations of mean wind speed, surge amplitude and frequency to assess the effect of unsteady aerodynamics on the response of the system. The thrust force, that plays a crucial role in the along-wind dynamics of a floating wind turbine mostly follows the quasi-steady theory. The near-wake of the wind turbine was studied by means of hot-wire measurements, and PIV was utilized to visualize the tip vortex. It is seen that the wake energy is increased in correspondence of the motion frequency and this is likely to be associated with the blade-tip vortex, which travel speed is modified in presence of surge motion.

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