Effects of Hydrodynamic Modelling in Fully Coupled Simulations of a Semi-submersible Wind Turbine

Kvittem, Marit Irene; Bachynski, Erin Elizabeth; Moan, Torgeir

doi:10.1016/j.egypro.2012.06.118

Cited by 83 publications

(37 citation statements)

References 10 publications

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“…The coupled nonlin ear TD analysis was performed using in Simo-Riflex-AeroDyn [25,26], Tower, blades, pontoons, braces, and mooring lines were modeled as flexible beam elements, and the columns and heave plates were taken as rigid bodies. Wave forces on the braces and pontoons were Morison type forces and forces on the columns were calculated according to potential theory by Wadam and an additional quadratic drag term.…”

Section: D Coupled Time Domain Modelmentioning

confidence: 99%

Frequency Versus Time Domain Fatigue Analysis of a Semisubmersible Wind Turbine Tower

Kvittem

Moan

2014

Journal of Offshore Mechanics and Arctic Engineering

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The current paper deals with a study of a semisubmersible wind turbine (WT), where short-term tower base bending moments and tower fatigue damage were estimated by a frequency domain (FD) method. Both a rigid structure assumption and a generalized degree-of-freedom (DOF) model for including the first flexible mode of the turbine tower were investigated. First, response to wind and wave loads was considered separately, then superposition was used to find the response to combined wind and wave loading. The bending moments and fatigue damage obtained by these methods were compared to results from a fully coupled, nonlinear time domain (TD) analysis. In this study a three column, catenary moored semisubmersible with the NREL 5 MW turbine mounted on one of the columns was modeled. The model was inspired by the WindFloat concept. The TD simulation tool used was Simo-Riflex-AeroDyn from Marintek and CeSOS. The FD method gave a good representation of the tower base bending moment histories for wave-only analyses, for the moderate sea states considered in these analyses. With the assumption that the structure is completely rigid, bending moments were underestimated, but including excitation of the elastic tower and blades, improved the results. The wind-induced low-frequency bending moments were not captured very well, which presumably comes from a combination of nonlinear effects being lost in the linearization of the thrust force and that the aerodynamic damping model was derived for a fixed turbine. Nevertheless, standard deviations of the bending moments were still reasonable. The FD model captured the combined wind and wave analyses quite well when a generalized coordinates model for wind excitation of the first bending mode of the turbine was included. The FD fatigue damage predictions were underestimated by 0–60%, corresponding to discrepancies in standard deviations of stress in the order of 0–20%.

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Section: D Coupled Time Domain Modelmentioning

confidence: 99%

Frequency Versus Time Domain Fatigue Analysis of a Semisubmersible Wind Turbine Tower

Kvittem

Moan

2014

Journal of Offshore Mechanics and Arctic Engineering

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“…Due to the increasing demand for energy and environmental protection concerns of the public, FOWTs have been developed rapidly in recent decades and have emerged as one of the most commercially promising form of clean energy. Worldwide, multiple prominent companies and research institutions have conducted research involving the use of a sequence of numerical simulation tools in OC3 and OC4 projects [1][2][3][4], and many simulation codes have been developed and improved for fully coupled analyses of FOWT systems [5][6][7][8][9]. Among these studies, several have been performed with a focus on spar-type FOWT concepts given their strong hydrodynamic performance.…”

Section: Introductionmentioning

confidence: 99%

Experimental comparisons of dynamic properties of floating wind turbine systems based on two different rotor concepts

Duan

Liu

et al. 2016

Applied Ocean Research

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a b s t r a c tThis article presents research findings on the response characteristic differences between the thrustmatched blade system (TMBS) and the geometry-matched blade system (GMBS), which utilize redesigned thrust-matched and original geometry-matched blades, respectively, both based on the OC3 spar-type floating offshore wind turbine (FOWT). Particulars of this research are to examine the unique dynamic response characteristics of the TMBS, which includes a better performance-matched rotor relative to the GMBS. The response behaviors of the TMBS and GMBS are compared and studied based on a sequence of wind and irregular wave scenarios to reveal the unique roles that the thrust-matched rotor plays in the dynamic response behaviors of the floating wind turbine system. Gyroscopic effects of rotor rotation are found weakened in the TMBS, and yaw oscillation in the TMBS is not solely excited by rotor rotation, unlike in the GMBS. Coupling effects between surge and pitch are found in both the TMBS and GMBS under combined wind-and-wave condition. Furthermore, restraining effects of wind loads on motions in the GMBS and TMBS are both evident at natural frequencies while show distinct behaviors at the wave frequency. It is observed from the experimental measurements that the tower-top bending moment of the TMBS shows similar oscillation characteristics as that of the GMBS but with larger oscillation amplitudes. Furthermore, it is found that tower-top shear force and axial rotor thrust of the TMBS show distinct exciting motivators and much larger oscillation amplitudes relative to those of the GMBS. For both the TMBS and GMBS, the tensions measured in mooring lines are found to be coupled by yaw motion for windonly cases while being clearly influenced by surge and heave couplings under integrated wind-and-wave load condition.

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“…The main focus of research on the production of wind power in deep water has been on horizontal‐axis wind turbines because of their commercial success in onshore applications. Different platforms have been used as the floating substructures to support the wind turbine, including spar, semi‐submersible and TLP types . Research has focused on the design, structural integrity, platform motion and installation of floating horizontal‐axis wind turbines (FHAWTs) to better understand the performance of different concepts and to provide the basis for detailed structural designs.…”

Section: Introductionmentioning

confidence: 99%

“…Research has focused on the design, structural integrity, platform motion and installation of floating horizontal‐axis wind turbines (FHAWTs) to better understand the performance of different concepts and to provide the basis for detailed structural designs. A variety of studies have been conducted on FHAWTs . However, the application of vertical‐axis wind turbines is also of interest in the offshore wind industry, and consequently, different concepts for floating vertical‐axis wind turbines (FVAWTs) have been presented, such as the DeepWind concept, the VertiWind concept and the Aerogenerator X concept, and studies have described their conceptual designs and evaluated their technical feasibility.…”

Section: Introductionmentioning

confidence: 99%

Stochastic dynamic response analysis of a floating vertical-axis wind turbine with a semi-submersible floater

2016

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Floating vertical-axis wind turbines (FVAWTs) provide the potential for utilizing offshore wind resources in moderate and deep water because of their economical installation and maintenance. Therefore, it is important to assess the performance of the FVAWT concept. This paper presents a stochastic dynamic response analysis of a 5 MW FVAWT based on fully coupled nonlinear time domain simulations. The studied FVAWT, which is composed of a Darrieus rotor and a semisubmersible floater, is subjected to various wind and wave conditions. The global motion, structural response and mooring line tension of the FVAWT are calculated using time domain simulations and studied based on statistical analysis and frequency-domain analysis. The response of the FVAWT is compared under steady and turbulent wind conditions to investigate the effects of turbulent wind. The advantage of the FVAWT in reducing the 2P effect on the response is demonstrated by comparing the floating wind turbine with the equivalent land-based wind turbine. Additionally, by comparing the behaviour of FVAWTs with flexible and rigid rotors, the effect of rotor flexibility is evaluated. Furthermore, the FVAWT is also investigated in the parked condition. The global motions and structural responses as a function of the azimuthal angle are studied. Finally, the dynamic response of the FVAWT in selected misaligned wind and wave conditions is analysed to determine the effects of wind-wave misalignment on the dynamic response.

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Effects of Hydrodynamic Modelling in Fully Coupled Simulations of a Semi-submersible Wind Turbine

Cited by 83 publications

References 10 publications

Frequency Versus Time Domain Fatigue Analysis of a Semisubmersible Wind Turbine Tower

Frequency Versus Time Domain Fatigue Analysis of a Semisubmersible Wind Turbine Tower

Experimental comparisons of dynamic properties of floating wind turbine systems based on two different rotor concepts

Stochastic dynamic response analysis of a floating vertical-axis wind turbine with a semi-submersible floater

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