scholarly journals Design and Analysis of a Braceless Steel 5-MW Semi-Submersible Wind Turbine

2016 ◽  
Author(s):  
Chenyu Luan ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Numerical Analysis ◽  
Wind Turbine ◽  
Global Analysis ◽  
Limit State ◽  
Dynamic Responses ◽  
Ultimate Limit State ◽  
Horizontal Axis Wind Turbine ◽  
Design Data ◽  
Intact Stability ◽  
Central Column

This paper introduces the design data and numerical analysis of a braceless steel semi-submersible wind turbine. The hull of the semi-submersible wind turbine is designed to support a reference 5-MW horizontal axis wind turbine at a site in the northern North Sea. The hull is composed of a central column, three side columns and three pontoons. The side columns and pontoons are arranged radially outward from the central column which is used to support the wind turbine. The side columns form the corners of a triangle on the horizontal plane and are connected by the pontoons to the central column at the bottom to form an integrated structure. Numerical analysis has been carried out to analyze the intact stability, natural periods and modes and global dynamic responses in winds and waves. Results of the numerical analysis show that the design has very good intact stability, well designed natural periods and modes, moderate rigid-body motions in extreme environmental conditions and a reasonable structural design. This paper emphasizes the structural responses of the hull considering both the global and local load effects. The global forces and moments in the hull are calculated by carrying out time-domain global analysis and used as inputs for simplified ultimate limit state design checks for structural strength of the hull. The design can be used as a reference semi-submersible wind turbine.

scholarly journals Platform for dynamic tests: preliminary studies, design and construction

2013 ◽  
Vol 6 (1) ◽  
pp. 55-74 ◽  
Author(s):  
J. E. Campuzano ◽  
R. de Castro ◽  
S. Ávila ◽  
G. Doz
Keyword(s):  
Natural Frequencies ◽  
Limit State ◽  
Physical Space ◽  
Dynamic Responses ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Dynamic Tests ◽  
Short Columns ◽  
Brazilian Standard ◽  
Design And Construction

This paper is about the design and construction of a platform for dynamic tests especially with people jumping, walking, etc. Initially it was tried to find out projects already implemented in platforms and dynamic tests and to study the loads produced by movement of people on slabs and the structural response to these loads. The limits established by different standards have been also studied for these dynamic responses, taking into account the ultimate limit state, as well as the structure in service, since the human body is very sensitive to structural vibrations. Parametric studies were performed considering various configurations of slabs (different spans, thicknesses and conditions of support) have been done, looking for a configuration that could have natural frequency close to the frequencies of the human loads. The slab should have dimensions compatible with the available physical space, fundamental frequency below 5 Hz and maximum immediate deflection compatible with the indications of the Brazilian standard NBR6118: 2007. Based on these criteria was chosen a rectangular structure consists of a solid reinforced concrete rectangular slab studded in two opposite edges of steel beams with shear connectors type U. The other two edges are free. The steel beams supporting the slab, in turn, are supported on eight metal profiles (two in each corner of the slab) that are supported on two to two short columns of steel profile H. Profiles U in steel are welded to four columns, forming a horizontal frame. Numerical analysis of the dynamic test platform have been performed for free and forced vibration, for obtaining the natural frequencies and corresponding vibration modes, considering the self-weight of the structure and the load that simulates people's weight. After obtaining a structural configuration that fulfilled the stipulated requirements, the design of the slab taking into account the recommendations of the Brazilian standard NBR6118: 2007. The platform was built and has been done a preliminary experimental study to obtain the first natural frequencies.

scholarly journals A comparison between the dynamics of horizontal and vertical axis offshore floating wind turbines

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140076 ◽  
Author(s):  
M. Borg ◽  
M. Collu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Static Stability ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Frequency Range ◽  
Aerodynamic Forces ◽  
Horizontal Axis Wind Turbine ◽  
Support Structure

The need to further exploit offshore wind resources in deeper waters has led to a re-emerging interest in vertical axis wind turbines (VAWTs) for floating foundation applications. However, there has been little effort to systematically compare VAWTs to the more conventional horizontal axis wind turbine (HAWT). This article initiates this comparison based on prime principles, focusing on the turbine aerodynamic forces and their impact on the floating wind turbine static and dynamic responses. VAWTs generate substantially different aerodynamic forces on the support structure, in particular, a potentially lower inclining moment and a substantially higher torque than HAWTs. Considering the static stability requirements, the advantages of a lower inclining moment, a lower wind turbine mass and a lower centre of gravity are illustrated, all of which are exploitable to have a less costly support structure. Floating VAWTs experience increased motion in the frequency range surrounding the turbine [number of blades]×[rotational speed] frequency. For very large VAWTs with slower rotational speeds, this frequency range may significantly overlap with the range of wave excitation forces. Quantitative considerations are undertaken comparing the reference NREL 5 MW HAWT with the NOVA 5 MW VAWT.

Dynamic Responses of Jacket-Type Offshore Wind Turbines Using Decoupled and Coupled Models

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Muk Chen Ong ◽  
Erin E. Bachynski ◽  
Ole David Økland
Keyword(s):  
Wind Turbines ◽  
Limit State ◽  
Coupled Model ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Ultimate Limit State ◽  
Coupled Models ◽  
Offshore Wind Turbines ◽  
Thrust And Torque ◽  
Rotor Model

This paper presents numerical studies of the dynamic responses of two jacket-type offshore wind turbines (OWTs) using both decoupled and coupled models. The investigated structures are the OC4 (Offshore Code Comparison Collaboration Continuation) jacket foundation and a full-lattice support structure presented by Long et al., 2012, “Lattice Towers for Bottom-Fixed Offshore Wind Turbines in the Ultimate Limit State: Variation of Some Geo metric Parameters,” ASME J. Offshore Mech. Arct. Eng., 134(2), p. 021202. Both structures support the NREL 5-MW wind turbine. Different operational wind and wave loadings at an offshore site with relatively high soil stiffness are investigated. In the decoupled (hydroelastic) model, the thrust and torque from an isolated rotor model were used as wind loads on the decoupled model together with a linear aerodynamic damper. The coupled model is a hydro-servo-aero-elastic representation of the system. The objective of this study is to evaluate the applicability of the computationally efficient linear decoupled model by comparing with the results obtained from the nonlinear coupled model. Good agreement was obtained in the eigen-frequency analysis, decay tests, and wave-only simulations. It was also found that, by applying the thrust force from an isolated rotor model in combination with linear damping, reasonable agreement could be obtained between the decoupled and coupled models in combined wind and wave simulations.

scholarly journals Investigating the loads and performance of a model horizontal axis wind turbine under reproducible IEC extreme operational conditions

2021 ◽  
Vol 6 (2) ◽  
pp. 477-489
Author(s):  
Kamran Shirzadeh ◽  
Horia Hangan ◽  
Curran Crawford ◽  
Pooyan Hashemi Tari
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Extreme Event ◽  
Horizontal Axis ◽  
Force Balance ◽  
Dynamic Responses ◽  
Horizontal Shear ◽  
Horizontal Axis Wind Turbine ◽  
Operational Conditions ◽  
Wind Shears

Abstract. The power generation and loading dynamic responses of a 2.2 m diameter horizontal axis wind turbine (HAWT) under some of the IEC 61400-1 transient extreme operational conditions, more specifically extreme wind shears (EWSs) and extreme operational gust (EOG), that were reproduced at the WindEEE Dome at Western University were investigated. The global forces were measured by a multi-axis force balance at the HAWT tower base. The unsteady horizontal shear induced a significant yaw moment on the rotor with a dynamic similar to that of the extreme event without affecting the power generation. The EOG severely affected all the performance parameters of the turbine.

Numerical Investigation of Actuator Disc Thickness Effect on Predicting the Performance and Far Wake of the Horizontal Axis Wind Turbine

2015 ◽  
Author(s):  
Ali Behrouzifar ◽  
Masoud Darbandi ◽  
Gerry E. Schneider
Keyword(s):  
Wind Turbine ◽  
Thickness Distribution ◽  
The Other ◽  
Thickness Effect ◽  
Navier Stokes ◽  
Constant Thickness ◽  
Horizontal Axis Wind Turbine ◽  
Design Data ◽  
Actuator Disc ◽  
Far Wake

In this paper, the actuator disk (AD) method is used to simulate the wind turbine performance and far-wake behavior. In this work, we incorporate the AD method with an axisymmetric full Navier-Stokes solver. In other words, the calculated AD load is suitably distributed on the disc to impose the aerodynamic forces acting on the blade. One important factor among various different factors, which affect the AD modeling prediction considerably, is the utilized grid thickness. In this work, we first choose the grid thickness recommended by the other researches and study the actual thickness of NREL 5MW wind turbine. Next, many other configurations are considered in our AD thickness modeling including a constant thickness and the actual thickness configurations. The latter one has a linear thickness distribution from 3.54 m at the root to 0.7 m at tip. The wind speed is ranged from 3 to 11 m/s consistent with the practical tests performed on the NREL 5MW wind turbine. We calculate the generated power for all the simulated configurations and their percentages of differences. The results show that the lowest difference is about 4.5% for a constant AD thickness of 0.2 m. Therefore, we conclude that the current AD model predicts results very close to the NREL design data. Additionally, this accurate prediction is similarly observed in the other ranges of wind turbine operational speeds.

scholarly journals Mooring System Design and Verification for a Floating Vertical Axis Wind Turbine

2020 ◽  
Vol 11 (03) ◽  
pp. 2050003
Author(s):  
Fausto Raschioni ◽  
Roberto Longo ◽  
Ali Mehmanparast ◽  
Cesare Mario Rizzo
Keyword(s):  
Wind Turbine ◽  
Limit State ◽  
Vertical Axis ◽  
Future Application ◽  
Ultimate Limit State ◽  
Mooring System ◽  
Vertical Axis Wind Turbine ◽  
Floating Wind Turbine ◽  
Crucial Part ◽  
Ultimate Limit

The aim of this study is to investigate the technical feasibility of an innovative vertical axis floating wind turbine concept with the main focus on the design and verification of the mooring system. The study is developed through iterative processes in order to identify the optimum design for the new floating wind turbine concept. The Ultimate Limit State (ULS) criteria have been considered to verify the integrity of the mooring system in the extreme environmental conditions with a 50-year return period. For this purpose, time domain dynamic analysis has been performed using the commercial software OrcaFlex [Orcina website, OrcaFlex software, https://www.orcina.com/ ]. Although the analysis is carried out for a specific site deemed suitable for the project, the results can be used as an input for any future application in other locations. The present study is intended to be a proof of concept with a proposed scientific framework for optimization of the mooring system which is considered to be a crucial part in the design of floating wind turbines due to their complex dynamic behavior.

scholarly journals Bio-Inspired Rotor Design Characterization of a Horizontal Axis Wind Turbine

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3515
Author(s):  
J. Gaitan-Aroca ◽  
Fabio Sierra ◽  
Jose Ulises Castellanos Contreras
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Analysis ◽  
Wind Turbine ◽  
Horizontal Axis ◽  
Experimental Results ◽  
Power Coefficient ◽  
Horizontal Axis Wind Turbine ◽  
Thrust Coefficient ◽  
Rotor Design

In this paper, the performance of a biomimetic wind rotor design inspired by Petrea Volubilis seed is presented. Experimentation for this rotor is configured as a horizontal axis wind turbine (HAWT) and numerical analysis is done in order to obtain performance curves with the open-source computational fluid dynamics (CFD) software OpenFoam®. Numerical analysis and experimental results are compared for power Coefficient (Cp) and thrust coefficient (CT). The biomimetic rotor analysis is also compared with experimental results exposed by Castañeda et al. (2011), who were the first to develop those experimentations with this new rotor design. Computational fluid dynamics simulations were performed using an incompressible large Edyy simulation (LES) turbulence models with a localized sub-grid scale (SGS) dynamic one-equation eddy-viscosity. A dynamic mesh based on an arbitrary mesh interface (AMI) was used to simulate rotation and to evaluate flow around rotor blades in order to accurately capture the flow field behavior and to obtain global variables that allow to determine the power potential of this wind rotor turbine. This study will show the potential of this new rotor design for wind power generation.

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