Single lift blade alignment for large offshore wind turbines: A critical assessment of the alignment process of next generation wind turbine blades (original) (raw)
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Energy demand from wind greatly increases, as such more remote sites need to be explored in order to find good wind resources. These remote sites are driving the industry further o↵shore and therefore into extreme wind and sea conditions. This push towards extreme conditions requires technological advancements concerning the wind turbine loads, power production and installation. The levelised cost of wind energy is strongly dependent on the capital expenditures and thus on the installation and logistics of erecting a wind turbine o↵shore. Improving the robustness of the installation to higher wind velocity and turbulence will increase the weather window and therefore drastically decrease the levelised cost of energy (LCoE). This thesis will focus on one particular technique of wind turbine installation: Horizontal Single Blade Mounting (HSBM).
Impact assessment of a wind turbine blade root during an offshore mating process
Engineering Structures, 2019
Single-blade installation is a popular method for installing blades on bottom-fixed offshore wind turbines. A jackup crane vessel is often employed, and individual blades with their roots equipped with mechanical joints and bolted connections are lifted to the tower-top height and mated with a pre-assembled hub. The final mating phase is challenging and faces significant risks of impact. Due to relative motions between the blade and the hub, substantial impact forces may arise and lead to severe structural damages at root connections, thereby causing delays in the installation task. The present paper considers a realistic scenario of the mating process and investigates the consequences of such impact loads. Here, a single-blade model with tugger lines and a monopile model were established using a multi-body formulation, and relative velocities under collinear wave and wind conditions were obtained. A three-dimensional finite element model was developed for the blade root with Tbolt connections, and an impact investigation was performed for the case in which a guiding connection impacts the hub. The results show severe bending and plastic deformation of the guide pin bolt together with failure of the adjoining composite laminate at the root connection. Based on the type of damage obtained for the different environmental conditions considered, this paper also discusses its consequence on the installation tasks and suggests onboard decision making in case of an impact incident. The results of this study provide new insights regarding the mating phase and can be utilised to establish response-based operational limits.
Development and application of a simulator for offshore wind turbine blades installation
Ocean Engineering, 2018
In an offshore environment, offshore wind energy resources are more available and stable, but the investment cost is much higher than that of onshore wind. The installation cost is a crucial factor of the investment. With the increasing number of planned and approved offshore wind farms, offshore wind turbine installation and relevant operations have received tremendous attention. Therefore, expediting the turbine-structure mating operations through a higher level of automation in offshore wind turbine installations may provide important economic benefits. To achieve a higher automation level and reduce the weather waiting time during the installation of offshore wind turbines, a flexible simulation-verification framework with high fidelity is needed. However, state-of-the-art wind turbine numerical analysis code is neither convenient nor open enough for applications concerning the design and verification of control algorithms. MATLAB/Simulink is among the most widely utilized numerical platforms by control engineers and researchers. This paper describes the development of a modularized blade installation simulation toolbox for the purpose of control design in MATLAB/Simulink. The toolbox can be used to simulate several blade installation configurations, both onshore and offshore. The paper presents the key features and equations of the different modules, exemplified by a single blade installation operation. Code-to-code verification results are presented and discussed with both quasi-steady wind and three-dimensional turbulent wind field.
DYNAMIC ANALYSIS OF A WIND TURBINE BLADE
ii | P a g e ACKNOWLEDGEMENT I am highly indebted to my mentor Dr. R. K. Behera for providing me the opportunity to work on this project under his able guidance. He has been great as a mentor and has motivated me thorough out my entire work duration. I am thankful to him for being so patient with me and for providing me with the necessary tools, knowledge and help to complete this project.
Aeroelastic coupling analysis of the flexible blade of a wind turbine
a b s t r a c t This paper presents an aeroelastic coupling analysis of the flexible blade of a large scale HAWT (horizontal axis wind turbine). To model the flexibility of the blade more accurately, 'SE' (super-element) is introduced to the blade dynamics model. The flexible blade is discretized into a MBS (multi-body system) using a limited number of SEs. The blade bending vibration and torsional deflection are both considered when calculating the aerodynamic loads; thus, the BEM (blade element momentum) theory used in this study is modified. In addition, the BeL (BeddoeseLeishman) dynamic stall model is integrated into the BEM-modified model to investigate the airfoil dynamic stall characteristics. The nonlinear governing equations of the constrained blade MBS are derived based on the theory of MBS dynamics coupling with the blade aerodynamics model. The time domain aeroelastic responses of the United States NREL (National Renewable Energy Laboratory) offshore 5-MW wind turbine blade are obtained. The simulation results indicate that blade vibration and deformation have significant effects on the aerodynamic loads, and the dynamic stall can cause more violent fluctuation for the blade aerodynamic loads compared with the steady aerodynamic model, which can considerably affect the blade fatigue load spectrum analysis and the fatigue life design. Energy xxx (2015) 1e9 Please cite this article in press as: Mo W, et al., Aeroelastic coupling analysis of the flexible blade of a wind turbine, Energy (2015), http:// dx.
Renewable Energy, 2013
This paper presents a model for the evaluation of aerodynamic and inertial contributions to a verticalaxis wind turbine (VAWT) blade deformation. Through the use of a specially designed coupling code, a solid modeling software, capable of generating the desired blade geometry depending on the design geometric parameters, is linked to a finite volume Computational Fluid Dynamic (CFD) code for the calculation of rotor performance and to a Finite Element Method (FEM) code for the structural design analysis of rotor blades. After describing the computational model and the relative validation procedure, a full RANS unsteady calculation is presented for a three-bladed rotor architecture, characterized by a NACA 0012 profile. Flow field characteristics are investigated for a constant unperturbed free-stream wind velocity of 9 m/s, determining the torque coefficient generated from the three blades as a function of rotor azimuthal coordinate. The emphasis is subsequently placed on obtaining an estimate for both pressure/tangential forces and centrifugal ones to blade structural loadings, thus assessing the influence of aerodynamic and inertial contributions to blade stresses and deformations.
A REVIEW PAPER OF PARAMETRIC ANALYSIS AND RESEARCH DIRECTIONS IN WIND TURBINE BLADES
This review paper describe the problems associated with adverse aerodynamic loads will grow more critical. Electricity production from wind energy has grown at a fast pace over the last few years. The size of individual wind turbines has also increased significantly and it is unclear if this trend can b sustained in the future for structural reasons, especially regarding rotor blade components. A research programme is being undertaken to investigate these issues, and finite element modelling will be extensively used to examine the static and dynamic limitations of wind turbine blades. As an initial step in this research, a flexible full blade model was created and is presented in this paper. The wind energy technical community has begun to seriously consider the potential of aerodynamic control methodologies for mitigating adverse aerodynamic loading. Spatial and temporal attributes of the structures and processes present in these flow fields hold important implications for active aerodynamic control methodologies currently being contemplated for wind turbine applications. The current work uses complementary experimental and computational methodologies, to isolate and characterize key attributes of blade flow fields associated with axisymmetric and yawed turbine operation. During axisymmetric operation, a highly three-dimensional, shear layer dominated flow field yields rotational augmentation of both mean and standard deviation levels of aerodynamic forces. Keywords – Wind Turbine Blades, Process Automation, blade variables
Structural analysis of offshore wind turbine blades using finite element method
Wind Engineering, 2019
Wind energy is one among the most promising renewable energy sources, and hence there is fast growth of wind energy farm implantation over the last decade, which is expected to be even faster in the coming years. Wind turbine blades are complex structures considering the different scientific fields involved in their study. Indeed, the study of blade performance involves fluid mechanics (aerodynamic study), solids mechanics (the nature of materials, the type of solicitations …), and the fluid coupling structure (IFS). The scope of the present work is to investigate the mechanical performances and structural integrity of a large offshore wind turbine blade under critical loads using blade element momentum. The resulting pressure was applied to the blade by the use of a user subroutine “DLOAD” implemented in ABAQUS finite element analysis software. The main objective is to identify and predict the zones which are sensitive to damage and failure as well as to evaluate the potential of c...
Dynamics of Offshore Wind Turbines
2011
The dynamic behavior of offshore wind turbines decides the design of several components, such as bearings, gear boxes, foundation platform and tower. In this paper, an analytical rotordynamic model of offshore wind turbine is developed and effects of several parameters, such as rotor blade size, rotational speed, distribution of mass imbalance, wind loading, wave loading, current speeds, and location of rotor-nacelle assembly are investigated on the dynamic behavior (response and stability) of an offshore wind turbine. It is particularly important to determine the rotor response for minimizing structural resonance and corresponding failure of wind turbine components. The dynamic response prediction is also desirable to address the fatigue design of wind turbine components. The rotordynamic model of the wind turbines is expressed as partial differential equations, with timedependent boundary conditions. These equations of motion are integrated with respect to time for a simple case o...