The Role of Active Flow-Control Devices in the Dynamic Aeroelastic Response of Wind Turbine Rotors PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Abstract : The significance of wind as a renewable source of power is growing with the increasing capacity of individual utility-scale wind turbines. Contemporary wind turbines are capable of producing up to 8 MW and consequently, their rotor sizes are rapidly growing in size. This has led to an increased emphasis on studies related to improvements and innovations in load-control methodologies. Most often than not, controlling the loads on an operational turbine is a precarious scenario, especially under high wind loading. The up-scaling of turbine rotors would thus benefit from a rationale change in load control through methodologies such as variable-speed stall, flexo-torsional adaptive blades, and active flow-control devices. This thesis work extends the capabilities of an aeroelastic code to provide a platform to analyze wind turbines with flow-control devices as active load control techniques. It also explores the effectiveness of such devices under rapid load-control scenarios relevant to benchmark turbines. Pre-determined rapid control actions such as pitching and trailing-edge flap actuation are implemented under nominal operating conditions. The benchmark turbine designed by National Renewable Energy Laboratory (NREL), which is an upwind three-bladed rotor rated at 5 MW forms the test bed for the current thesis study. The goal is to obtain an overall understanding of the aeroelastic rotor response of utility-scale wind turbines under rapid control actions, paying special attention to the power of actuation.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Abstract : The significance of wind as a renewable source of power is growing with the increasing capacity of individual utility-scale wind turbines. Contemporary wind turbines are capable of producing up to 8 MW and consequently, their rotor sizes are rapidly growing in size. This has led to an increased emphasis on studies related to improvements and innovations in load-control methodologies. Most often than not, controlling the loads on an operational turbine is a precarious scenario, especially under high wind loading. The up-scaling of turbine rotors would thus benefit from a rationale change in load control through methodologies such as variable-speed stall, flexo-torsional adaptive blades, and active flow-control devices. This thesis work extends the capabilities of an aeroelastic code to provide a platform to analyze wind turbines with flow-control devices as active load control techniques. It also explores the effectiveness of such devices under rapid load-control scenarios relevant to benchmark turbines. Pre-determined rapid control actions such as pitching and trailing-edge flap actuation are implemented under nominal operating conditions. The benchmark turbine designed by National Renewable Energy Laboratory (NREL), which is an upwind three-bladed rotor rated at 5 MW forms the test bed for the current thesis study. The goal is to obtain an overall understanding of the aeroelastic rotor response of utility-scale wind turbines under rapid control actions, paying special attention to the power of actuation.
Author: Fernando D. Bianchi Publisher: Springer Science & Business Media ISBN: 1846284937 Category : Technology & Engineering Languages : en Pages : 219
Book Description
This book emphasizes the application of Linear Parameter Varying (LPV) gain scheduling techniques to the control of wind energy conversion systems. This reformulation of the classical problem of gain scheduling allows straightforward design procedure and simple controller implementation. From an overview of basic wind energy conversion, to analysis of common control strategies, to design details for LPV gain-scheduled controllers for both fixed- and variable-pitch, this is a thorough and informative monograph.
Author: Leonardo Bergami Publisher: Springer ISBN: 3319073656 Category : Technology & Engineering Languages : en Pages : 161
Book Description
A smart rotor is a wind turbine rotor that, through a combination of sensors, control units and actuators actively reduces the variation of the aerodynamic loads it has to withstand. Smart rotors feature promising load alleviation potential and might provide the technological breakthrough required by the next generation of large wind turbine rotors. The book presents the aero-servo-elastic model of a smart rotor with Adaptive Trailing Edge Flaps for active load alleviation and provides an insight on the rotor aerodynamic, structural and control modeling. A novel model for the unsteady aerodynamics of an air foil section with flap is presented and coupled with a multi-body structural representation. A smart rotor configuration is proposed, where the Adaptive Trailing Edge Flaps extend along the outer 20 % of the blade span. Linear Quadratic and Model Predictive algorithms are formulated to control the flap deflection. The potential of the smart rotor is finally confirmed by simulations in a turbulent wind field. A significant reduction of the fatigue loads on the blades is reported: the flaps, which cover no more than 1.5 % of the blade surface, reduce the fatigue load by 15 %; a combination of flap and individual pitch control allows for fatigue reductions up to 30 %.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Abstract : Greater penetration of wind energy demands better utilization of available wind. This has led to a formidable increase in the rotor diameter over the past few years. Bigger rotors call for lighter, more flexible blades to reduce loads and improve fatigue life. As a result, future blades will deform substantially more than the relatively stiff blades of the past. More efficient use of wind power also calls for incorporating advanced active and passive control strategies and increasing the range of velocities over which wind energy is captured. Hence an improvement in the quality of numerical simulations capable of capturing the effects of these deformations is key to innovations in windturbine technology. The code on which this research aims to improve upon is called the Dynamic Rotor Deformation - Blade Element Momentum model (DRD-BEM) introduced by Ponta et al. It combines an advanced structural model with an aerodynamic model implemented in a parallel HPC supercomputer platform. The structural part simulates the response of heterogeneous composite blades, based on a variation of the dimensional reduction technique proposed by Hodges and Yu. This approach reduces the 3-Dimensional complexity of the blade section into a stiffness matrix for an equivalent beam, substantially reducing the computational effort required to model the structural dynamics at every time step. The aerodynamic model is based on an advanced implementation of the Blade Element Momentum (BEM) theory, where all velocities and forces are re-projected into the deformed configuration at that instant. This ensures that the effects of all the complex modes of rotor deformation and subsequent rotation of airfoil sections are accounted for while computing the aerodynamic forces. As a result of the out of plane attitudes of the rotor sections introduced by blade deformations and various control strategies the hitherto small radial component of aerodynamic forces in the hub must now be taken into account. In this research we present a way to extend the capabilities of DRD-BEM by taking into consideration the 3-Dimensional effects of these forces on rotor interference. In this method, called the 3-D DRD-BEM, the coordinate system where the momentum balance is performed in BEM theory is moved, from the hub, to the instantaneous position and alignment of the blade section in its deformed configuration. Another aspect that becomes important as blades become more flexible and control strategies become more complex, is the high axial induction factor regime of turbine operation. This becomes more evident in the instaneous blade section coordinate system of the 3-D DRD-BEM. In most implementations of BEM, this flow regime is modeled using empirical relations based on experimental data with no consensus on which empirical relation to use. This research uses CFD solutions to develop an improved actuator disk model and revisit the above mentioned experiments for a more accurate representation of these operational states.
Author: Emmanuel Branlard Publisher: Springer ISBN: 3319551647 Category : Technology & Engineering Languages : en Pages : 632
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: Publisher: ISBN: Category : Aeronautics Languages : en Pages : 580
Book Description
A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)
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Author: Fernando D. Bianchi
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