Hydrodynamic Analysis of Floating Docks With Alternative Geometries for Floating Wind Turbine Installation

2020 ◽  
Author(s):  
Viktor A. Gran ◽  
Zhiyu Jiang ◽  
Zhiyuan Pan
Keyword(s):  
Wind Turbine ◽  
Spar Platform ◽  
Hydrodynamic Analysis ◽  
Response Characteristics ◽  
Floating Wind Turbine ◽  
Neck Area ◽  
Wave Heights ◽  
Potential Improvement ◽  
Future Work ◽  
Piston Mode

Abstract Installation of spar floating wind turbine offshore is a challenging task. Usually, the spar platform is upended first, and mating of the tower assembly with the spar platform is assisted by a crane vessel. Due to motions of the spar platforms and of the crane vessel, such an operation often takes place in shielded areas with relatively small wave heights and wind speed. The floating dock concept has been recently proposed to expand the weather window for installing spar floating wind turbines. The idea is to use a cylindrical dock to shield the spar platform from wave excitations. However, because of the trapped internal fluid, the cylindrical geometry is subjected to piston mode and sloshing mode excitations, and these modes may fall in the wave periods and cause unfavourable response characteristics. This paper investigates the influence of floating dock geometries on the piston and sloshing modes. We assumed a homogeneous mass distribution of the floating dock and changed the geometry of the cylindrical dock by expanding or reducing the neck area. Then, hydrodynamic analysis of the alternative geometries was carried out using a potential flow code. By comparing the system’s piston modes and sloshing modes, we identified the trend of variation and found that an expanded neck area can lead to increased sloshing period and piston mode. This indicates a potential improvement of the dock responses in operating sea states. The results of this analysis can be used in the shape design optimisation in a future work.

Short-Term Extreme Motions of a Spar Floating Wind Turbine Estimated Through a 1:30 At-Sea Experiment

2018 ◽  
Author(s):  
Carlo Ruzzo ◽  
Nilanjan Saha ◽  
Felice Arena
Keyword(s):  
Wind Turbine ◽  
Degrees Of Freedom ◽  
Extreme Values ◽  
Model Structure ◽  
Ocean Engineering ◽  
Short Term ◽  
Spar Platform ◽  
Six Degrees Of Freedom ◽  
Floating Wind Turbine ◽  
Scale Models

The present paper deals with the estimation of the short-term extreme motions of a spar floating wind turbine in parked rotor conditions, through a 1:30 at-sea experiment, carried out at the Natural Ocean Engineering Laboratory (NOEL) of Reggio Calabria (Italy). Thanks to some favorable local environmental conditions of the site, several wind-generated sea states with relatively low significant wave height (Hs < 0.50 m) have been collected during the experiment. These sea states are scale models of ocean storms, which are relevant hydrodynamic design conditions for the spar platform. The 30-minutes extreme values of the model structure motions have been estimated for all the six degrees of freedom, using the Weibull Tail Method (WTM), and the results obtained are presented in the paper. Such estimations are 1:30 scale models of the 3-hours extreme values of the spar motions in parked rotor conditions and may be directly used for design purposes.

scholarly journals Response Characteristics of the DeepCwind Floating Wind Turbine Moored by a Single-Point Mooring System

2018 ◽  
Vol 8 (11) ◽  
pp. 2306 ◽  
Author(s):  
Yingyi Liu ◽  
Shigeo Yoshida ◽  
Hiroshi Yamamoto ◽  
Akinori Toyofuku ◽  
Guanghua He ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Numerical Study ◽  
Single Point ◽  
Offshore Wind ◽  
Response Characteristics ◽  
Floating Wind Turbine ◽  
Decay Test ◽  
Response Amplitude Operators ◽  
Marine Engineering ◽  
Offshore Oil

In recent years, the SPM (Single-Point Mooring) concept has been widely employed in several branches of the naval architecture and marine engineering field, such as FPSOs (Floating Production, Storage and Offloading units), offshore oil rigs, etc., but not yet popular in the offshore wind energy. To investigate the response characteristics of an SPM-moored FWT (Floating Wind Turbine), in the present work, we perform a numerical study on the DeepCwind semisubmersible wind turbine, using the state-of-the-art open-source tool FAST. The free-decay test results show that the SPM layout affects the natural periods of the wind turbine in rotational modes, as well as the mooring stiffness of the diagonal rotational and crossing rotational-translational terms, especially in relation to the yaw mode. Comparisons of the RAOs (Response Amplitude Operators) elucidate that the presence of wind influences significantly the sway, roll and yaw motions of the SPM layout. Finally, the weathervane test shows that an asymmetry exists in the free-yaw motion response when the semisubmersible wind turbine is moored by an SPM system.

Research on the Influence of Helical Strakes and Its Parameters on Dynamic Response of Platform of Floating Wind Turbine Based on Optimization Method of Orthogonal Design

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Qinwei Ding ◽  
Chun Li ◽  
Binxin Li ◽  
Wenxing Hao ◽  
Zhou Ye
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Orthogonal Design ◽  
Exciting Force ◽  
Design Parameters ◽  
Spar Platform ◽  
Floating Wind Turbine ◽  
Helical Strakes ◽  
Pitch Ratio ◽  
The Impact

The stability of platform is the most fundamental guarantee for the safe operation of floating wind turbine in complex marine environment. The helical strakes used on spar platform in the traditional oil industry are useful and effective. This paper is to investigative the validity of helical strakes when used for offshore wind energy harvesting. The National Renewable Energy Laboratory (NREL) 5 MW wind turbine based on OC3-Hywind spar-buoy platform with the attachment of helical strakes is modeled for the purpose to analysis the impact of helical strakes and its design parameters (number, height, and pitch ratio) on the dynamic response of the floating wind turbine spar platform. The dynamic response of spar platform under wind, wave, and current loads is calculated and analyzed based on the radiation and diffraction theory, the finite element method, and the orthogonal design method. The research result shows that the helical strakes can effectively suppress the dynamic response of the platform but enlarge the wave exciting force, and helical strakes cannot change peak frequency of response amplitude operator (RAO) and wave exciting force of spar in frequency-domain. The best parameter combination is two pieces of helical strakes with height of 15%D and the pitch ratio of 5. Height and pitch ratio of the helical strakes have significant influence on pitch response, while the number and interaction of height and pitch ratio have slight effect.

Effects of heave plate on dynamic response of floating wind turbine Spar platform under the coupling effect of wind and wave

2020 ◽  
Vol 201 ◽  
pp. 107103 ◽  
Author(s):  
Minnan Yue ◽  
Qingsong Liu ◽  
Chun Li ◽  
Qinwei Ding ◽  
Shanshan Cheng ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Coupling Effect ◽  
Spar Platform ◽  
Floating Wind Turbine ◽  
Heave Plate

scholarly journals Design and Installation of a Hybrid-Spar Floating Wind Turbine Platform

2015 ◽  
Author(s):  
Tomoaki Utsunomiya ◽  
Iku Sato ◽  
Osamu Kobayashi ◽  
Takashi Shiraishi ◽  
Takashi Harada
Keyword(s):  
Wind Turbine ◽  
Prestressed Concrete ◽  
Unique Feature ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Spar Platform ◽  
Design Load ◽  
Floating Wind Turbine ◽  
Precast Prestressed Concrete ◽  
Nagasaki Prefecture

A floating offshore wind turbine platform supporting a 2MW downwind-type turbine was successfully installed offshore of Kabashima Island, Goto city, Nagasaki prefecture, Japan on October 18, 2013. It has been operating since October 28, 2013 as the first grid-connected multi-megawatt floating wind turbine in Japan. The spar platform has a unique feature, that is, the upper part of the spar is made of steel (as usual) but the lower part is made of precast prestressed concrete (PC). Such a configuration is referred to as hybrid-spar. In this paper, the design methodology of the hybrid spar is presented — including environmental design conditions, DLCs (Design Load Cases), dynamic analysis, fatigue analysis, etc. Also, the installation procedure is presented briefly.

Fluid-structure interaction and stress analysis of a floating wind turbine

2021 ◽  
Vol 78 ◽  
pp. 102970
Author(s):  
B. Wiegard ◽  
M. König ◽  
J. Lund ◽  
L. Radtke ◽  
S. Netzband ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Stress Analysis ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Floating Wind Turbine
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