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.

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.

Installation Vessel and Method for Offshore Wind Turbine in Ultra-Shallow Water

2010 ◽  
Author(s):  
Huiqu Fan ◽  
Jinbao Lin ◽  
Qingsong Shi
Keyword(s):  
Wind Turbine ◽  
Shallow Water ◽  
Wind Turbines ◽  
Wind Farm ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wind Speeds ◽  
Total Investment ◽  
Key Issues ◽  
Turbine Installation

Compared to onshore wind turbines, offshore wind turbines take advantage of wind speeds which are more constant and stronger than those on land. Since many large electricity load centers are located near coastline in China, larger wind turbines can be installed closer to these areas to supply energy in a more economical way. Wind turbine transportation and installation are key issues for offshore wind farm construction, especially for large size turbine installation in ultra-shallow water like intertidal zone with water depth less than 5m. The traditional installation vessels with large design drafts are likely to be trapped in shallow water zones. It is usually impossible to carry out turbine installation in shallow water. This paper presents a set of innovative installation vessel concept and corresponding methods for ultra-shallow water zone include ultra-shallow draft crane vessel and ultra-shallow draft barge. The main purpose is to simplify the installation procedures and reduce total investment.

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.

Offshore Wind Turbine and Substructure Modelling for a Float Over Installation Design

2009 ◽  
Author(s):  
Jean-Marc Cholley ◽  
M. Cahay
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farm ◽  
Oil And Gas ◽  
Cost Effective ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Heavy Lift ◽  
Offshore Oil And Gas ◽  
Turbine Installation

We can learn from the offshore oil and gas experience for the future offshore wind turbine installation. For the offshore ‘wind farm’ developments, the installation of wind turbines onto preinstalled foundations using the heavy lift vessel method or stabilized vessel is now well established, though, for large units, this requires multiple lifts and hence extensive offshore assembling. As demand for lift vessels increases, their availability to match a future large specific project’s schedule cannot be guaranteed. Consequently, an alternative wind turbine installation vessel design has been developed for not only installing simultaneously two wind turbines in a single piece, but also with a high air gap (up to 70 ft). This paper presents this new design. The new vessel design consists of a catamaran shaped vessel with dimensions that permit it to go around variety of substructures (piles foundation, tripod, concrete foundation or floating substructure) for float-over installation of wind turbines. For the float-over operation, a thorough understanding of dynamic behavior and environmental conditions are necessary to allow the design load to be assessed, with the objective to minimize the risk and maximize the operating sea states. This paper gives a description of how the substructure / Wind turbine / transition piece / floating unit can be modeled. This new vessel design greatly extends the geographical range for offshore wind turbine installation using the float-over method and offers a cost effective alternative to relying on crane vessels.

scholarly journals Low-Height Lifting System for Offshore Wind Turbine Installation: Modelling and Hydrodynamic Response Analysis Using the Commercial Simulation Tool SIMA

2020 ◽  
Author(s):  
David Vågnes ◽  
Thiago Gabriel Monteiro ◽  
Karl Henning Halse ◽  
Hans Petter Hildre
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Weather Conditions ◽  
Economic Feasibility ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Offshore Wind Turbines ◽  
Lifting System

Abstract With the increasing demand for renewable energy sources in the past years, the interest in expanding the use of wind energy has grown. The next frontier in this expansion process is the use of floating wind turbines offshore. One of the main factors dictating the economic feasibility of such wind turbines is the complexity of their installation process. The dimensions of modern offshore wind turbines, the distance from the installation sites to the coast and demanding environmental factors all contribute to the difficult of developing an efficient installation concept for this kind of structures. In this work, we present a new concept for a catamaran vessel capable of handling the deployment of offshore wind turbines on floating spar platforms using a low-height lifting system that connects to the lower end of the wind turbine. The low-height lifting system is controlled by an active heave compensation system and constant tension tugger wires attached to the turbine mid-section are used to ensure the balance of the tower during the installation process. We conducted a series of hydrodynamic analysis using the software suit SIMA to study the dynamic response of the proposed system under different weather conditions and different operational layouts. This preliminary concept was proven feasible from a hydrodynamic point of view and can now be pushed forward for further studies regarding other aspects of the operation, such as impact and structural loads and mechanical design of components.

Numerical Study on Aero-Hydrodynamics With Inter-Turbine Spacing Variation for Two Floating Offshore Wind Turbines

2019 ◽  
Author(s):  
Yang Huang ◽  
Decheng Wan
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Numerical Study ◽  
Offshore Wind ◽  
Hydrodynamic Characteristics ◽  
Offshore Wind Turbine ◽  
Analysis Tool ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Spacing Variation

Abstract To investigate the influence of the inter-turbine spacing on the performance of the floating offshore wind turbine (FOWT) in the floating wind farm, coupled aero-hydrodynamic simulations of two spar-type FOWT models with inter-turbine spacing variation under shear wind and regular wave conditions are performed in the present work. An unsteady actuator line model (UALM) is embedded into in-house code naoe-FOAM-SJTU to establish a fully coupled CFD analysis tool for numerical simulations of FOWTs. From the simulation results, the unsteady aerodynamic power and thrust are obtained, and the hydrodynamic responses including the six-degree-of-freedom motions and mooring tensions are available. Detailed flow visualizations of wake velocity profiles and vortex structures are also illustrated. The coupled performance of floating offshore wind turbines with inter-turbine spacing variation are analyzed, and the influences of inter-turbine spacing on aero-hydrodynamic characteristics of coupled wind-wave flow field are discussed. It is found that the power output of downstream wind turbine increases with inter-turbine spacing. Coupled aero-hydrodynamic characteristics of flow filed are significantly affected by inter-turbine spacing.

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.

scholarly journals Improving the Strategy of Maintaining Offshore Wind Turbines through Petri Net Modelling

2021 ◽  
Vol 11 (2) ◽  
pp. 574
Author(s):  
Rundong Yan ◽  
Sarah Dunnett
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Petri Net ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Maintenance Costs ◽  
Offshore Wind Turbines ◽  
Major Repair ◽  
Wind Turbine System ◽  
Periodic Maintenance

In order to improve the operation and maintenance (O&M) of offshore wind turbines, a new Petri net (PN)-based offshore wind turbine maintenance model is developed in this paper to simulate the O&M activities in an offshore wind farm. With the aid of the PN model developed, three new potential wind turbine maintenance strategies are studied. They are (1) carrying out periodic maintenance of the wind turbine components at different frequencies according to their specific reliability features; (2) conducting a full inspection of the entire wind turbine system following a major repair; and (3) equipping the wind turbine with a condition monitoring system (CMS) that has powerful fault detection capability. From the research results, it is found that periodic maintenance is essential, but in order to ensure that the turbine is operated economically, this maintenance needs to be carried out at an optimal frequency. Conducting a full inspection of the entire wind turbine system following a major repair enables efficient utilisation of the maintenance resources. If periodic maintenance is performed infrequently, this measure leads to less unexpected shutdowns, lower downtime, and lower maintenance costs. It has been shown that to install the wind turbine with a CMS is helpful to relieve the burden of periodic maintenance. Moreover, the higher the quality of the CMS, the more the downtime and maintenance costs can be reduced. However, the cost of the CMS needs to be considered, as a high cost may make the operation of the offshore wind turbine uneconomical.

scholarly journals Impact of Typhoons on Floating Offshore Wind Turbines: A Case Study of Typhoon Mangkhut

2021 ◽  
Vol 9 (5) ◽  
pp. 543
Author(s):  
Jiawen Li ◽  
Jingyu Bian ◽  
Yuxiang Ma ◽  
Yichen Jiang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Safety Evaluation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Coupling Motion

A typhoon is a restrictive factor in the development of floating wind power in China. However, the influences of multistage typhoon wind and waves on offshore wind turbines have not yet been studied. Based on Typhoon Mangkhut, in this study, the characteristics of the motion response and structural loads of an offshore wind turbine are investigated during the travel process. For this purpose, a framework is established and verified for investigating the typhoon-induced effects of offshore wind turbines, including a multistage typhoon wave field and a coupled dynamic model of offshore wind turbines. On this basis, the motion response and structural loads of different stages are calculated and analyzed systematically. The results show that the maximum response does not exactly correspond to the maximum wave or wind stage. Considering only the maximum wave height or wind speed may underestimate the motion response during the traveling process of the typhoon, which has problems in guiding the anti-typhoon design of offshore wind turbines. In addition, the coupling motion between the floating foundation and turbine should be considered in the safety evaluation of the floating offshore wind turbine under typhoon conditions.

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