scholarly journals A Feasibility Study for Using Fishnet to Protect Offshore Wind Turbine Monopile Foundations from Damage by Scouring

2019 ◽  
Vol 9 (23) ◽  
pp. 5023 ◽  
Author(s):  
Bo Yang ◽  
Kexiang Wei ◽  
Wenxian Yang ◽  
Tieying Li ◽  
Bo Qin ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Wind Turbine ◽  
Laboratory Tests ◽  
Numerical Study ◽  
Experimental Tests ◽  
Cost Effective ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Effective Measure ◽  
Flow Coupling

Offshore wind turbine monopile foundations are subjected to complex wind, wave, and flow coupling effects, which result in seabed scouring around the monopile. The consequent scour pits threaten the reliability, safety, and load-carrying capacity of the monopile. In order to develop a cost-effective measure to mitigate such an issue, a new countermeasure device, named “fishnet”, is studied in this paper using a combined approach of numerical simulations and experimental tests. In the research, the size of the fishnet, diameter of the fishnet thread, and the installation height of the fishnet were optimized in order to achieve the best protection to the monopile foundation. In the paper, both numerical simulations and laboratory tests proved the effectiveness of the proposed “fishnet” in reducing the scour around the wind turbine monopile foundations. Moreover, its contribution to erosion reduction can be further enhanced via optimization. It was found that, after optimization, the maximum shear force on the seabed could be reduced by 14% in the numerical study, and the maximum depth of the scour pit could be reduced by 38.2% in laboratory tests.

Experimental and Numerical Study of the Influence of Drag Coefficient on Snap Loads in Mooring Lines of a Floating Offshore Wind Turbine

2021 ◽  
Author(s):  
Brendan Guillouzouic ◽  
François Pétrié ◽  
Vincent Lafon ◽  
Fabien Fremont
Keyword(s):  
Numerical Simulations ◽  
Drag Coefficient ◽  
Wind Turbine ◽  
Scale Effects ◽  
Numerical Study ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Bodies ◽  
Mooring Lines ◽  
Floating Offshore Wind Turbine

Abstract Mooring is one of the key components of a floating offshore wind turbine since the mooring rupture may lead to the total loss of one or even several turbines in a farm. Even if a large experience in moorings of floating bodies was gained in the oil & gas industry, the renewable energies face new challenges such as reducing the cost as much as possible, reducing the footprint to limit environmental impact or avoid any interference between mooring lines and electrical cables in a farm composed of several tens of turbines. Those constraints may lead to designs suffering snap loads which shall be avoided as far as practicable or addressed with a particular attention, as this quasi-instantaneous stretching of the mooring lines may lead to very high tensions governing the design. This paper presents the results of physical model tests and numerical simulations performed on a typical floating wind turbine concept of semi-submersible type. Both qualitative and quantitative comparisons are performed. The objective is to provide guidelines for FOWT mooring designers regarding the selection of the drag coefficient to consider. A very significant influence of the line’s drag coefficient, on both the probability of occurrence and the magnitude of snap loads, was found. This subject is hereby fully documented on a given case study and general discussions on scale effects, marine growth effects and other parameters are also made. The numerical simulations were performed using the dynamic analysis software ‘OrcaFlex’. The experiments have been carried out by Océanide, in south of France.

Numerical Study for a Catamaran Gripper-Monopile Mechanism of a Novel Offshore Wind Turbine Assembly Installation Procedure

2017 ◽  
Author(s):  
Lars Ivar Hatledal ◽  
Houxiang Zhang ◽  
Karl Henning Halse ◽  
Hans Petter Hildre
Keyword(s):  
Numerical Simulations ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Numerical Study ◽  
Weather Conditions ◽  
Rolling Contact ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Contact Points ◽  
Turbine Installation

Current methods for installation of offshore wind turbines are all sensitive to the weather conditions and the present cost level of offshore wind power is more than twice the cost of land-based units, increasing with water depth. This paper presents numerical simulations of a novel experimental gripper design to reduce the environmental effects applied to a catamaran type of vessel during wind turbine installation. In SFI MOVE project in NTNU Aalesund, our team proposed a novel wind turbine installation process. A new catamaran vessel will carry pre-assembled wind turbines to the installation location. Two new designed grippers on the deck will make a lifting operation to install the wind turbine onto the turbine foundation. Three prismatic grippers with several rolling contact points at the end are attached in an arc at the catamaran’s aft, designed to grasp the turbine foundation in order to make a connection between the two in the horizontal plane. This paper will only emphasize the contact responses between the turbine foundation and the three grippers during the wind turbine installation process. Numerical simulations are carried out using the virtual prototyping framework Vicosim which is developed by NTNU Aalesund. The simulation results show validation of a key part of the proposed new wind turbine installation idea.

scholarly journals Numerical study of various geometries of breakwaters for the installation of floating wind turbines

2016 ◽  
Vol 13 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Keyvan Esmaeelpour ◽  
Rouzbeh Shafaghat ◽  
Rezvan Alamian ◽  
Rasoul Bayani
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Numerical Study ◽  
Energy Resources ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Renewable Energy Resources ◽  
Time Step ◽  
Set Up ◽  
The Right

The everyday growing populations all over the world and the necessity of increase in consumption of fossil energies have made the human to discover new energy resources, which are clean, cheap and renewable. Wind energy is one of the renewable energy resources. Considerable wind speed has made settling of wind turbines at sea beneficial and appealing. For this purpose, choosing the appropriate plates to set up wind turbines on the surface of sea is necessary. Regarding the installation condition, by choosing suitable geometry for floating breakwaters, offshore wind turbine can be mounted on them. Suitable geometry of breakwater for multifunctional usage could be selected with analyzing and comparing pressure, force and moment produced by incoming waves. In this article, we implement boundary element method to solve governing differential equations by assuming potential flow. On the other hand, for promoting free surface in each time step, we employed Euler-Lagrangian method. Finally, to find the appropriate geometry for installing the wind turbine on the breakwater, moment and wave profile next to the right and left side of breakwater body are calculated. Among simulated geometries, breakwater with trapezoid geometry which its larger base is placed in the water has more sustainability and it is the most suitable geometry for wind turbine installation.

Development of Floating Offshore Wind Turbine and the Mooring System

2013 ◽  
Vol 790 ◽  
pp. 634-637
Author(s):  
Xue Liang Zhao ◽  
Wei Ming Gong
Keyword(s):  
Wind Turbine ◽  
Research Work ◽  
Experimental Tests ◽  
Offshore Wind ◽  
Future Research ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Floating Offshore Wind Turbine ◽  
Energy Demands

The offshore wind turbine, especially the floating offshore wind turbine in the deep sea is a perspective technology in the context of increasing energy demands. Mooring system, as an important unit of the floating offshore wind turbine is emphasized. The methods of in-situ test and the laboratory experimental tests are reviewed. Some new testing methods are discussed. The most commonly used anchor systems are explored. The paper aims to present some future research work that is important for the development of the floating offshore wind turbine technology.

scholarly journals Efficient preliminary floating offshore wind turbine design and testing methodologies and application to a concrete spar design

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140350 ◽  
Author(s):  
Denis Matha ◽  
Frank Sandner ◽  
Climent Molins ◽  
Alexis Campos ◽  
Po Wen Cheng
Keyword(s):  
Wind Turbine ◽  
Design Process ◽  
Experimental Tests ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Testing Methodology ◽  
Cost Of Energy ◽  
Turbine Design ◽  
Design And Testing

The current key challenge in the floating offshore wind turbine industry and research is on designing economic floating systems that can compete with fixed-bottom offshore turbines in terms of levelized cost of energy. The preliminary platform design, as well as early experimental design assessments, are critical elements in the overall design process. In this contribution, a brief review of current floating offshore wind turbine platform pre-design and scaled testing methodologies is provided, with a focus on their ability to accommodate the coupled dynamic behaviour of floating offshore wind systems. The exemplary design and testing methodology for a monolithic concrete spar platform as performed within the European KIC AFOSP project is presented. Results from the experimental tests compared to numerical simulations are presented and analysed and show very good agreement for relevant basic dynamic platform properties. Extreme and fatigue loads and cost analysis of the AFOSP system confirm the viability of the presented design process. In summary, the exemplary application of the reduced design and testing methodology for AFOSP confirms that it represents a viable procedure during pre-design of floating offshore wind turbine platforms.

scholarly journals Hydrodynamic Response of the Deep Turbine Installation-Floating Concept

2019 ◽  
Author(s):  
Jordi Serret ◽  
Tim Stratford ◽  
Philipp R. Thies ◽  
Vengatesan Venugopal ◽  
Tahsin Tezdogan
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Mooring Lines ◽  
Scaled Model ◽  
Irregular Wave ◽  
Floating System ◽  
Turbine Installation

Abstract Floating offshore wind turbine (FOWT) installations are progressing from the R&D stage to commercial installation projects. The prospective sites are situated in increasingly deeper water and further away from the shore. This paper presents the Deep Turbine Installation-Floating (DTI-F) concept, an innovative hybrid spar buoy-based FOWT capable of being able to raise and lower the tower and nacelle, which simplifies construction, installation, maintenance and decommissioning. The study is focused on the hydrodynamics of the moored floating system, and it is based on experimental and numerical modelling work. A 1:45 Froude scaled model of the DTI-F wind concept was tested using three different mooring configurations: i) three mooring lines, ii) four mooring lines, and iii) three mooring lines with a delta connection. Free decay and stiffness decay tests were carried out together with regular and irregular wave tests. The numerical study comprises diffraction (ANSYS AQWA) and time-domain modelling (OrcaFlex). The experimental hydrostatic and hydrodynamic results are compared with the numerical simulations based on the as-built scale model. Considering the natural frequencies results obtained for the three mooring configurations, the three lines configuration without delta connection was selected as the most suitable design. The obtained results for the three mooring lines configuration show good agreement between the experiment and numerical simulations. The presented analysis of the design concept indicates a high degree of technical feasibility.

scholarly journals Numerical study of a concept for major repair and replacement of offshore wind turbine blades

Wind Energy ◽  
2020 ◽  
Vol 23 (8) ◽  
pp. 1673-1692
Author(s):  
Wilson Guachamin‐Acero ◽  
Zhiyu Jiang ◽  
Lin Li
Keyword(s):  
Wind Turbine ◽  
Numerical Study ◽  
Turbine Blades ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wind Turbine Blades ◽  
Major Repair
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