Investigation of wind speed effect on the dynamics of a typical offshore floating wind turbine

The pitch motion of the Offshore Floating Wind Turbine (OFWT) introduces additional wind speed to the rotor. The additional wind speed distributes linearly along the vertical altitude, which is called as the platform-pitch-induced wind shear effect in this paper. Comparisons between the typical wind shear and the platform-pitch-induced wind shear are conducted with the Free Vortex Method (FVM) for the NREL 5MW baseline wind turbine. It is found that the platform-pitch-induced wind shear is the results of the rotor rotating and platform pitching, and its wind speed profile is time-varying. At the designed point of tip speed ratio of 7, the averaged power output is reduced slightly under the typical wind shear while it is increased by 4% under the platform-pitch-induced wind shear. The aerodynamic loads of the OFWT under the platform pitch-induced wind shear experience much more considerable variations than the typical wind shear, which introduce severer fatigue damages to the OFWT components. For the sake of the safety of the OFWT, advanced control strategy and superior design should be developed to mitigate the platform pitch motion.

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Effects of Surge on Rotor Aerodynamics of Offshore Floating Wind Turbine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1070-1072.177 ◽

2014 ◽

Vol 1070-1072 ◽

pp. 177-182 ◽

Cited By ~ 1

Author(s):

Jin Chao Liu ◽

Ke Sun ◽

Jian Hua Zhang ◽

Yu Na Zhao ◽

Mao Hua Pan

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Linear Correlation ◽

Reference Data ◽

Aerodynamic Loads ◽

Rotor Aerodynamics ◽

Momentum Theory ◽

Floating Wind Turbine ◽

Offshore Floating Wind Turbine ◽

Delay Correction

This paper, using the blade momentum theory combined with dynamic inflow correction and stall delay correction, analyses how periodic surge affect rotor aerodynamics of the NREL 5MW turbine operating at three different regions of its power curve. Results show that surge has the largest effects on rotor aerodynamics in region under rated wind speed while the smallest in region above that. Besides, oscillation amplitudes of rotor aerodynamic loads are in linear correlation with surge frequency and amplitude in most cases, except that rotor power and torque in region above rated wind speed is in linear correlation with the square of surge frequency. Results of this analysis would provide reference data for designs of floating wind turbine systems.

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Dynamic Modeling of an Offshore Floating Wind Turbine for Application in the Mediterranean Sea

Energies ◽

10.3390/en14010248 ◽

2021 ◽

Vol 14 (1) ◽

pp. 248

Author(s):

Lorenzo Cottura ◽

Riccardo Caradonna ◽

Alberto Ghigo ◽

Riccardo Novo ◽

Giovanni Bracco ◽

...

Keyword(s):

Wind Turbine ◽

Mediterranean Sea ◽

Wind Farm ◽

Reference Model ◽

Wide Spectrum ◽

Wind Farms ◽

Offshore Wind ◽

Floating Wind Turbine ◽

The Mediterranean ◽

Offshore Floating Wind Turbine

Wind power is emerging as one of the most sustainable and low-cost options for energy production. Far-offshore floating wind turbines are attractive in view of exploiting high wind availability sites while minimizing environmental and landscape impact. In the last few years, some offshore floating wind farms were deployed in Northern Europe for technology validation, with very promising results. At present time, however, no offshore wind farm installations have been developed in the Mediterranean Sea. The aim of this work is to comprehensively model an offshore floating wind turbine and examine the behavior resulting from a wide spectrum of sea and wind states typical of the Mediterranean Sea. The flexible and accessible in-house model developed for this purpose is compared with the reference model FAST v8.16 for verifying its reliability. Then, a simulation campaign is carried out to estimate the wind turbine LCOE (Levelized Cost of Energy). Based on this, the best substructure is chosen and the convenience of the investment is evaluated.

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Passive and semi-active control of an offshore floating wind turbine using a tuned liquid column damper

IFAC-PapersOnLine ◽

10.1016/j.ifacol.2015.10.287 ◽

2015 ◽

Vol 48 (16) ◽

pp. 241-247 ◽

Cited By ~ 18

Author(s):

Christophe Coudurier ◽

Olivier Lepreux ◽

Nicolas Petit

Keyword(s):

Wind Turbine ◽

Active Control ◽

Liquid Column ◽

Tuned Liquid Column Damper ◽

Floating Wind Turbine ◽

Offshore Floating Wind Turbine ◽

Liquid Column Damper

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On the importance of nonlinear hydrostatic stiffness of offshore floating wind turbine platforms

Applied Ocean Research ◽

10.1016/j.apor.2021.102730 ◽

2021 ◽

Vol 113 ◽

pp. 102730

Author(s):

Zahid Ullah ◽

Naik Muhammad ◽

Dong-Ho Choi

Keyword(s):

Wind Turbine ◽

Floating Wind Turbine ◽

Offshore Floating Wind Turbine

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Comparison of Spar and Semisubmersible Floater Concepts of Offshore Wind Turbines Using Long-Term Analysis

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4031312 ◽

2015 ◽

Vol 137 (6) ◽

Cited By ~ 6

Author(s):

Hasan Bagbanci ◽

D. Karmakar ◽

C. Guedes Soares

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Transfer Functions ◽

Probability Distributions ◽

Offshore Wind ◽

Short Term ◽

Offshore Wind Turbines ◽

Floating Wind Turbine ◽

Offshore Floating Wind Turbine

The long-term probability distributions of a spar-type and a semisubmersible-type offshore floating wind turbine response are calculated for surge, heave, and pitch motions along with the side-to-side, fore–aft, and yaw tower base bending moments. The transfer functions for surge, heave, and pitch motions for both spar-type and semisubmersible-type floaters are obtained using the fast code and the results are also compared with the results obtained in an experimental study. The long-term predictions of the most probable maximum values of motion amplitudes are used for design purposes, so as to guarantee the safety of the floating wind turbines against overturning in high waves and wind speed. The long-term distribution is carried out using North Atlantic wave data and the short-term floating wind turbine responses are represented using Rayleigh distributions. The transfer functions are used in the procedure to calculate the variances of the short-term responses. The results obtained for both spar-type and semisubmersible-type offshore floating wind turbine are compared, and the study will be helpful in the assessments of the long-term availability and economic performance of the spar-type and semisubmersible-type offshore floating wind turbine.

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Investigations of Unsteady Aerodynamics of an Offshore Floating Wind Turbine With Platform Motions Using Dual-Sliding Method

Volume 12: Wind Energy ◽

10.1115/gt2020-14350 ◽

2020 ◽

Author(s):

Xiaodong Wang ◽

Zhaoliang Ye ◽

Ziwen Chen ◽

Yize Guo ◽

Yujun Qiao

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Aerodynamic Performance ◽

Offshore Wind ◽

Sliding Mesh ◽

Unsteady Aerodynamic ◽

Floating Wind Turbine ◽

Mesh Method ◽

Offshore Floating Wind Turbine ◽

Platform Motions

Abstract Offshore wind energy developed rapidly in recent years. Due to the platform motions causing by ocean waves, the aerodynamics of floating offshore wind turbines (FOWT) show strong unsteady characters than onshore wind turbines. The widely used methods to investigate the unsteady aerodynamic performance of wind turbine are Blade Element Momentum (BEM) and Free-Vortex Wake (FVW) methods. The accuracy of these two methods strongly depend on empirical formula or correction models. However, for dynamics motions of wind turbine, there is still a lack of accurate models. CFD simulations using overset or dynamic mesh methods also have been used for FOWT aerodynamic investigations. However, the mesh deforming or reconstruction methods are usually suitable for small movement of wind turbine blade. In this paper, a dual-sliding mesh method is employed to simulate the unsteady aerodynamic characters of an offshore floating wind turbine with supporting platform motions using Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. Both rotor rotation and platform motions are treated as rigid angular motions. The relative motion and data exchange were simulated using sliding mesh method. The NREL 5MW reference wind turbine with platform pitching and rolling motions are considered. The pitching and rolling motions of floating platform are simplified in the form of a prescribed sinusoidal function. Different conditions with two amplitudes and two frequencies of pitching and rolling motions were investigated. URANS were performed with full structured mesh for wind turbine rotor using commercial software FLUENT. The platform motions were set using User Defined Function (UDF). Transitional Shear Stress Turbulence (T-SST) model was employed. The simulation results were compared with BEM method and FVW method results. Both steady status and dynamic pitching processes are investigated. The variations of wind turbine aerodynamic load, as well as the aerodynamic character of airfoils at different spanwise positions, were obtained and analyzed in detail. The simulations results show that the platform pitching introduce remarkable influence on the wind turbine aerodynamic performance. The platform pitching has much larger influence on the wind turbine power and thrust than the platform rolling. The dual-sliding mesh method shows potentials to investigation the dynamic process with multiple rigid motions.

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