SMART AERODYNAMIC CONTROL DEVICES DESIGN AND VIBRATION REDUCTION ANALYSIS FOR WIND TURBINE BLADES PDF Download

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Languages : en
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Abstract : This study aims to design several types of aerodynamic control devices using smart material actuators to reduce the vibration fatigue load of wind turbine blades. The concepts of piezo stack actuator based smart external and internal flaps were detailed, including the basic flap layout, the operating range, the settings, etc. The concept of ionic polymer metal composite based microflap was also detailed. In order to compensate the aerodynamic force, centrifugal force and gravitational force acting on the flap under the wind turbine's normal operational conditions, the required energy output from the actuators was calculated. To meet the energy requirements, the configuration of actuator array was determined. Amplification systems were designed to enhance the displacement output at the expense of the force output. In addition, a universal flap control scheme was developed using the multiblade coordinate transformation, the gain scheduling technique and the proportional-integral-derivative controller. A series of aeroelastic-aerodynamic time marching simulations were performed on the NREL 5MW wind turbine with the designed flap systems and control scheme in order to obtain the time responses. The time domain data was analyzed from a fatigue perspective. The result shows there are significant reductions in the vibration fluctuation and the damage equivalent loads, with respect to the blade out-of-plane deflection and the blade root flapwise bending moment. To further investigate the effects of flap on the natural frequency of the wind turbine, the operational modal analysis was used to extract the modal parameters from the operating wind turbine. However, the operational modal analysis cannot be directly applied to the time series, which is because the assumptions are violated for the operating wind turbine and the harmonic frequencies raised from the rotational motion mask quantities of natural frequencies of the structural modes. In order to overcome this problem, a cepstral harmonic removal method was developed based on a mathematic development of a modified notch lifter. After the linearization direct eigenvalue analysis and the operational modal analysis were applied, both results show that the flap system slightly reduces the resonance frequencies.

Author: J. G.Holierhoek
Publisher: Elsevier Inc. Chapters
ISBN: 0128089164
Category : Technology & Engineering
Languages : en
Pages : 30

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Aeroelasticity concerns the interaction between aerodynamics, dynamics and elasticity. This interaction can result in negatively or badly damped wind turbine blade modes, which can have a significant effect on the turbine lifetime. The first aeroelastic problem that occurred on commercial wind turbines concerned a negatively damped edgewise mode. It is important to ensure that there is some out-of-plane deformation in this mode shape to prevent the instability. For larger turbine blades with lower torsional stiffness and the possibility of higher tip speeds for the offshore designs, classical flutter could also become relevant. When designing a wind turbine blade, it is therefore crucial that there is enough damping for the different modes and that there is no coincidence of natural frequencies with excitation frequencies (resonance). An effective aeroelastic analysis is also important, and the tools used for such an analysis must include the necessary detail in the structural model.

Author: Povl Brondsted
Publisher: Woodhead Publishing
ISBN: 0081030088
Category : Technology & Engineering
Languages : en
Pages : 516

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Advances in Wind Turbine Blade Design and Materials, Second Edition, builds on the thorough review of the design and functionality of wind turbine rotor blades and the requirements and challenges for composite materials used in both current and future designs of wind turbine blades. Reviews the design and functionality of wind turbine rotor blades Examines the requirements and challenges for composite materials used in both current and future designs of wind turbine blades Provides an invaluable reference for researchers and innovators in the field of wind

Author: Jin Chen
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 3110383748
Category : Science
Languages : en
Pages : 405

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Wind Turbine Airfoils and Blades introduces new ideas in the design of wind turbine airfoils and blades based on functional integral theory and the finite element method, accompanied by results from wind tunnel testing. The authors also discuss the optimization of wind turbine blades as well as results from aerodynamic analysis. This book is suitable for researchers and engineers in aeronautics and can be used as a textbook for graduate students.

Author: I. Kade Wiratama
Publisher:
ISBN:
Category :
Languages : en
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As a result of the significant growth of wind turbines in size, blade load control has become the main challenge for large wind turbines. Many advanced techniques have been investigated aiming at developing control devices to ease blade loading. Individual pitch control system, adaptive blades, trailing edge microtabs, morphing aerofoils, ailerons, trailing edge flaps, and telescopic blades are among these techniques. Most of the above advanced technologies are currently implemented in, or are under investigation to be utilised, for blade load alleviation. The present study aims at investigating the potential benefits of these advanced techniques in enhancing the energy capture capabilities rather than blade load alleviation. To achieve this goal the research is carried out in three directions: (i) development of a simulation software tool suitable for wind turbines utilising nonconventional control systems, (ii) development of a blade design optimisation tool capable of optimising the topology of blades equipped with nonconventional control systems, and (iii) carrying out design optimisation case studies with the objective of power extraction enhancement towards investigating the feasibility of advanced technologies, initially developed for load alleviation of large blades, for power extraction enhancement. Three nonconventional control systems, namely, microtab, trailing edge flap and telescopic blades are investigated. A software tool, AWTSim, is especially developed for aerodynamic simulation of wind turbines utilising blades equipped with microtabs and trailing edge flap as well as telescopic blades. As part of the aerodynamic simulation of these wind turbines, the control system must be also simulated. The simulation of the control system is carried out via solving an optimisation problem which gives the best value for the controlling parameter at each wind turbine run condition. Developing a genetic algorithm optimisation tool which is especially designed for wind turbine blades and integrating it with AWTSim, a design optimisation tool for blades equipped with nonconventional control system is constructed. The design optimisation tool, AWTSimD, is employed to carry out design case studies. The results of design case studies reveal that for constant speed rotors, optimised telescopic blades are more effective than flaps and microtabs in power enhancement. However, in comparison with flap and microtabs, telescopic blades have two disadvantages: (i) complexity in telescopic mechanism and the added weight and (ii) increased blade loading. It is also shown that flaps are more efficient than microtabs, and that the location and the size of flaps are key parameters in design. It is also shown that optimisation of the blade pretwist has a significant influence on the energy extraction enhancement. That is, to gain the maximum benefit of installing flaps and microtabs on blades, the baseline blades must be redesigned.

Author: Emmanuel Branlard
Publisher: Springer
ISBN: 3319551647
Category : Technology & Engineering
Languages : en
Pages : 632

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Book Description
The book introduces the fundamentals of fluid-mechanics, momentum theories, vortex theories and vortex methods necessary for the study of rotors aerodynamics and wind-turbines aerodynamics in particular. Rotor theories are presented in a great level of details at the beginning of the book. These theories include: the blade element theory, the Kutta-Joukowski theory, the momentum theory and the blade element momentum method. A part of the book is dedicated to the description and implementation of vortex methods. The remaining of the book focuses on the study of wind turbine aerodynamics using vortex-theory analyses or vortex-methods. Examples of vortex-theory applications are: optimal rotor design, tip-loss corrections, yaw-models and dynamic inflow models. Historical derivations and recent extensions of the models are presented. The cylindrical vortex model is another example of a simple analytical vortex model presented in this book. This model leads to the development of different BEM models and it is also used to provide the analytical velocity field upstream of a turbine or a wind farm under aligned or yawed conditions. Different applications of numerical vortex methods are presented. Numerical methods are used for instance to investigate the influence of a wind turbine on the incoming turbulence. Sheared inflows and aero-elastic simulations are investigated using vortex methods for the first time. Many analytical flows are derived in details: vortex rings, vortex cylinders, Hill's vortex, vortex blobs etc. They are used throughout the book to devise simple rotor models or to validate the implementation of numerical methods. Several Matlab programs are provided to ease some of the most complex implementations.

Author: C. Bak
Publisher: Elsevier Inc. Chapters
ISBN: 0128089148
Category : Technology & Engineering
Languages : en
Pages : 58

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Book Description
This chapter describes the process of aerodynamic rotor design for horizontal axis wind turbines. Apart from describing the state-of-the-art, it presents the mathematical models used, explains how airfoil and rotor control choice are decided and lists common design constraints. An example is used to illustrate the rotor design process, covering all the main aspects from choice of rotor size, airfoil types and number of blades to the exact aerodynamic shape of the blades. At the end of the chapter there is a summary of future trends and sources of further information.

Author: Víctor Maldonado
Publisher:
ISBN:
Category : Technology
Languages : en
Pages :

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Active flow control is a technique to improve the fluid dynamics of an aerodynamic body utilizing an active actuator and energy input. Much progress on the application of active flow control techniques for wind turbine blades has been accomplished in the last decade. The main focus has been on regulating unsteady aerodynamic blade loads and vibration by controlling the flow locally along the blade. The trailing edge flap and synthetic jet actuator have emerged among the most effective actuators for wind turbines. This chapter gives an overview of active flow control techniques, with a specific focus on the application and use of the piezoelectric synthetic jet for vibration reduction of small-scale wind turbine blade models tested in a wind tunnel. Using the techniques presented, the global flow field over the blade was altered such that flow separation was mitigated. Consequently, this resulted in a significant decrease in the vibration of the blade. Particle image velocimetry (PIV) was used to quantify the flow field over the blade. Using synthetic jets, the flow over the blade was either fully or partially reattached, depending on the angle of attack. Current and future research in this field has evolved to understanding and controlling realistic 3D vortex flows typical of actual wind turbines utilizing scaled-down rotor platforms. To this end, the author presents the design and operation of a rotor test tower with custom blades embedded with synthetic jet actuators aimed at investigating multi-scale blade tip vortex interaction and breakdown that may lead to blade vibration and noise reduction.

Author: Bryce Bautista Aquino
Publisher:
ISBN:
Category :
Languages : en
Pages : 78

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With wind turbines growing in size, operation and maintenance has become a more important area of research with the goal of making wind energy more profitable. Wind turbine blades are subjected to intense fluctuating loads that can cause significant damage over time. The need for advanced methods of alleviating blade loads to extend the lifespan of wind turbines has become more important as worldwide initiatives have called for a push in renewable energy. An area of research whose goal is to reduce the fatigue damage is smart rotor control. Smart bladed wind turbines have the ability to sense aerodynamic loads and compute an actuator response to manipulate the aerodynamics of the wind turbine. The wind turbine model for this research is equipped with two different smart rotor devices. Independent pitch actuators for each blade and trailing edge flaps (TEFs) on the outer 70 to 90% of the blade span are used to modify aerodynamic loads. Individual Pitch Control (IPC) and Individual Flap Control (IFC) are designed to control these devices and are implemented on the NREL 5 MW wind turbine. The consequences of smart rotor control lie in the wind turbine's power capture in below rated conditions. Manipulating aerodynamic loads on the blades cause the rotor to decelerate, which effectively decreases the rotor speed and power output by 1.5%. Standard Region 2 generator torque control laws do not take into consideration variations in rotor dynamics which occur from the smart rotor controllers. Additionally, this research explores new generator torque control algorithms that optimize power capture in below rated conditions. FAST, an aeroelastic code for the simulation of wind turbines, is utilized to test the capability and efficacy of the controllers. Simulation results for the smart rotor controllers prove that they are successful in decreasing the standard deviation of blade loads by 26.3% in above rated conditions and 12.1% in below rated conditions. As expected, the average power capture decreases by 1.5%. The advanced generator torque controllers for Region 2 power capture have a maximum average power increase of 1.07% while still maintaining load reduction capabilities when coupled with smart rotor controllers. The results of this research show promise for optimizing wind turbine operation and increasing profitability.

Author: Wai Hou (Alan) Lio
Publisher: Springer
ISBN: 3319755323
Category : Technology & Engineering
Languages : en
Pages : 193

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This thesis investigates the use of blade-pitch control and real-time wind measurements to reduce the structural loads on the rotors and blades of wind turbines. The first part of the thesis studies the main similarities between the various classes of current blade-pitch control strategies, which have to date remained overlooked by mainstream literature. It also investigates the feasibility of an estimator design that extracts the turbine tower motion signal from the blade load measurements. In turn, the second part of the thesis proposes a novel model predictive control layer in the control architecture that enables an existing controller to incorporate the upcoming wind information and constraint-handling features. This thesis provides essential clarifications of and systematic design guidelines for these topics, which can benefit the design of wind turbines and, it is hoped, inspire the development of more innovative mechanical load-reduction solutions in the field of wind energy.