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Dynamic Wake Studies Of A Flatback Airfoil
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Book Synopsis Dynamic Wake Studies of a Flatback Airfoil by : Christopher E. Mertes
Download or read book Dynamic Wake Studies of a Flatback Airfoil written by Christopher E. Mertes and published by . This book was released on 2012 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was conducted to characterize the effects of pitching motion on vortex shedding behavior in the wake of a flatback airfoil. Experiments were conducted on a static, rigidly mounted airfoil as well as an oscillating airfoil in a wind tunnel facility at the University of Wyoming. Particle image velocimetry was used in conjunction with proper orthogonal decomposition to show that the vortex shedding does behave differently depending on the dynamic configuration of the airfoil. The results show that fundamental vortex shedding from the blunt trailing edge is present in both the static and dynamic case whenever the flow is attached. In a case where the flow separates under dynamic stall conditions, the flow physics are dominated by the dynamic pitching motion, and trailing edge vortex shedding is only present during the attached portion of the pitching cycle. In another case, it was shown that the organization of the vortex shedding changes depending on the point in the oscillation cycle. This dynamic behavior has an impact on the aerodynamic characteristics of the blade.An experimental study was conducted to characterize the effects of pitching motion on vortex shedding behavior in the wake of a flatback airfoil. Experiments were conducted on a static, rigidly mounted airfoil as well as an oscillating airfoil in a wind tunnel facility at the University of Wyoming. Particle image velocimetry was used in conjunction with proper orthogonal decomposition to show that the vortex shedding does behave differently depending on the dynamic configuration of the airfoil. The results show that fundamental vortex shedding from the blunt trailing edge is present in both the static and dynamic case whenever the flow is attached. In a case where the flow separates under dynamic stall conditions, the flow physics are dominated by the dynamic pitching motion, and trailing edge vortex shedding is only present during the attached portion of the pitching cycle. In another case, it was shown that the organization of the vortex shedding changes depending on the point in the oscillation cycle. This dynamic behavior has an impact on the aerodynamic characteristics of the blade.
Book Synopsis Investigation of Transition and Vortex Systems of a Dynamically Pitching Airfoil Under the Free-stream Turbulence Conditions by : Anurag Gandhi
Download or read book Investigation of Transition and Vortex Systems of a Dynamically Pitching Airfoil Under the Free-stream Turbulence Conditions written by Anurag Gandhi and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of reduced frequency on dynamic stall behavior of a pitching NACA0012 airfoil in a turbulent wake using Direct Numerical Simulations is presented in the current study. Upstream turbulence with dynamically oscillating blades and airfoils is associated with ambient flow unsteadiness and is encountered in many operating conditions. Wake turbulence, a more realistic scenario for airfoils in operation, is generated using a small solid cylinder placed upstream, the vortices shed from which interact with the pitching airfoil affecting dynamic stall behavior. A recently developed moving overlapping grid approach is used using a high-order Spectral Element Method (SEM) for spatial discretization combined with a dynamic time-stepping procedure allowing for up to third order temporal discretization. Two cases of reduced frequency (k = 0:16 and 0:25) for airfoil oscillation are investigated and the change in dynamic stall behavior with change in reduced frequency is studied and documented using flow-fields and aerodynamic coefficients (Drag, Lift and Pitching Moment) with a focus on understanding vortex system dynamics (including formation of secondary vortices) for different reduced frequencies and it's affect on airfoil aerodynamic characteristics and fatigue life. Transition of the flow over the surface of an airfoil for both undisturbed and disturbed flow cases will also be discussed using Pressure coefficient and Skin Friction coefficient data for a given cycle combined with a wavelet analysis using Morse wavelets in MATLAB.
Book Synopsis Optimization of Wind Turbine Airfoils/blades and Wind Farm Layouts by : Xiaomin Chen (Mechanical engineer)
Download or read book Optimization of Wind Turbine Airfoils/blades and Wind Farm Layouts written by Xiaomin Chen (Mechanical engineer) and published by . This book was released on 2014 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shape optimization is widely used in the design of wind turbine blades. In this dissertation, a numerical optimization method called Genetic Algorithm (GA) is applied to address the shape optimization of wind turbine airfoils and blades. In recent years, the airfoil sections with blunt trailing edge (called flatback airfoils) have been proposed for the inboard regions of large wind-turbine blades because they provide several structural and aerodynamic performance advantages. The FX, DU and NACA 64 series airfoils are thick airfoils widely used for wind turbine blade application. They have several advantages in meeting the intrinsic requirements for wind turbines in terms of design point, off-design capabilities and structural properties. This research employ both single- and multi-objective genetic algorithms (SOGA and MOGA) for shape optimization of Flatback, FX, DU and NACA 64 series airfoils to achieve maximum lift and/or maximum lift to drag ratio. The commercially available software FLUENT is employed for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a two-equation Shear Stress Transport (SST) turbulence model and a three equation k-kl-[omega] turbulence model. The optimization methodology is validated by an optimization study of subsonic and transonic airfoils (NACA0012 and RAE 2822 airfoils). All the optimization results have demonstrated that the GA technique can be employed efficiently and accurately to produce globally optimal airfoils with excellent aerodynamic properties using a desired objective value (minimum Cd and/or maximum Cl /Cd). It is also shown that the multi-objective genetic algorithm based optimization can generate superior airfoils compared to those obtained by using the single objective genetic algorithm. The applications of thick airfoils are extended to the assessment of wind turbine performance. It is well established that the power generated by a Horizontal-Axis Wind Turbine (HAWT) is a function of the number of blades B, the tip speed ratio [lambda] (blade tip speed/wind free stream velocity) and the lift to drag ratio (Cl /Cd) of the airfoil sections of the blade. The airfoil sections used in HAWT are generally thick airfoils such as the S, DU, FX, Flat-back and NACA 6-series of airfoils. These airfoils vary in (Cl /Cd) for a given B and [lambda], and therefore the power generated by HAWT for different blade airfoil sections will vary. Another goal of this study is to evaluate the effect of different airfoil sections on HAWT performance using the Blade Element Momentum (BEM) theory. In this dissertation, we employ DU 91-W2-250, FX 66-S196-V1, NACA 64421, and Flat-back series of airfoils (FB-3500-0050, FB-3500-0875, and FB-3500-1750) and compare their performance with S809 airfoil used in NREL Phase II and III wind turbines; the lift and drag coefficient data for these airfoils sections are available. The output power of the turbine is calculated using these airfoil section blades for a given B and [lambda] and is compared with the original NREL Phase II and Phase III turbines using S809 airfoil section. It is shown that by a suitable choice of airfoil section of HAWT blade, the power generated by the turbine can be significantly increased. Parametric studies are also conducted by varying the turbine diameter. In addition, a simplified dynamic inflow model is integrated into the BEM theory. It is shown that the improved BEM theory has superior performance in capturing the instantaneous behavior of wind turbines due to the existence of wind turbine wake or temporal variations in wind velocity. The dissertation also considers the Wind Farm layout optimization problem using a genetic algorithm. Both the Horizontal -Axis Wind Turbines (HAWT) and Vertical-Axis Wind Turbines (VAWT) are considered. The goal of the optimization problem is to optimally position the turbines within the wind farm such that the wake effects are minimized and the power production is maximized. The reasonably accurate modeling of the turbine wake is critical in determination of the optimal layout of the turbines and the power generated. For HAWT, two wake models are considered; both are found to give similar answers. For VAWT, a very simple wake model is employed. Finally, some preliminary investigation of shape optimization of 3D wind turbine blades at low Reynolds numbers is conducted. The optimization employs a 3D straight untapered wind turbine blade with cross section of NACA 0012 airfoils as the geometry of baseline blade. The optimization objective is to achieve maximum Cl /Cd as well as maximum Cl. The multi-objective genetic algorithm is employed together with the commercially available software FLUENT for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a one-equation Sparlart-Allmaras turbulence model. The results show excellent performance of the optimized wind turbine blade and indicate the feasibility of optimization on real wind turbine blades with more complex shapes in the future.
Book Synopsis Study on the Vortex Wake of an Airfoil Equipped with Flexible Trailing Edge Fringes by : Zhengkai He
Download or read book Study on the Vortex Wake of an Airfoil Equipped with Flexible Trailing Edge Fringes written by Zhengkai He and published by . This book was released on 2014 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the inspiration of owl's silent flight, a traditional airfoil S833 equipped with flexible fringes on the trailing edge is investigated through numerical simulation and experiments in a wind tunnel. The newly constructed airfoil is modeled and numerically investigated. An incompressible, 2D and viscous flow solver in the Computational Fluid Dynamics (CFD) software FLUENT is utilized to conduct the numerical simulation on the vortex flow feature in the wake of the airfoil. A User Defined Function code was applied to generate the defined motion of flexible fringes. The effects of the flapping frequency of the fringe and the deformation pattern of the fringe are investigated in the parametric study. On the other hand, the airfoil model with the flexible fringe is manufactured for the experimental study. A digital Particle Image Velocimetry (PIV) system is employed to investigate the flow structure in the wake and the deformation of the flexible fringes. The motion of the trailing edge fringes is extracted from the experimental measurements as the input for CFD simulation. It has been found that the addition of the flexible fringe has a significant effect on the flow characteristics in the vortex wake downstream of the airfoil as well as the aerodynamic performance of the airfoil.
Download or read book Trusts written by and published by . This book was released on 19?? with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ephemera collection contains documents of everyday life generally covering publications of fewer than five pages. These may include: advertising material, area guides, booklets, brochures, samples of merchandise postcards, posters, programs, stickers and tickets.
Book Synopsis Experimental Studies of Transonic Airfoil Trailing Edge and Wake Flowfield Properties by : Deems Shelton Emmer
Download or read book Experimental Studies of Transonic Airfoil Trailing Edge and Wake Flowfield Properties written by Deems Shelton Emmer and published by . This book was released on 1984 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Low-Speed Wind Tunnel Testing by : Jewel B. Barlow
Download or read book Low-Speed Wind Tunnel Testing written by Jewel B. Barlow and published by John Wiley & Sons. This book was released on 1999-02-22 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt: A brand-new edition of the classic guide on low-speed wind tunnel testing While great advances in theoretical and computational methods have been made in recent years, low-speed wind tunnel testing remains essential for obtaining the full range of data needed to guide detailed design decisions for many practical engineering problems. This long-awaited Third Edition of William H. Rae, Jr.'s landmark reference brings together essential information on all aspects of low-speed wind tunnel design, analysis, testing, and instrumentation in one easy-to-use resource. Written by authors who are among the most respected wind tunnel engineers in the world, this edition has been updated to address current topics and applications, and includes coverage of digital electronics, new instrumentation, video and photographic methods, pressure-sensitive paint, and liquid crystal-based measurement methods. The book is organized for quick access to topics of interest, and examines basic test techniques and objectives of modeling and testing aircraft designs in low-speed wind tunnels, as well as applications to fluid motion analysis, automobiles, marine vessels, buildings, bridges, and other structures subject to wind loading. Supplemented with real-world examples throughout, Low-Speed Wind Tunnel Testing, Third Edition is an indispensable resource for aerospace engineering students and professionals, engineers and researchers in the automotive industries, wind tunnel designers, architects, and others who need to get the most from low-speed wind tunnel technology and experiments in their work.
Book Synopsis Direct Numerical Simulations, Resolvent Analysis, and Flow Control of Laminar Post-stall Wakes Around Finite Tapered Swept Wings by : Jean Helder Marques Ribeiro
Download or read book Direct Numerical Simulations, Resolvent Analysis, and Flow Control of Laminar Post-stall Wakes Around Finite Tapered Swept Wings written by Jean Helder Marques Ribeiro and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: External flows over wings is a traditional flow of interest in aerodynamics. Over the last century, research efforts were dedicated to studying the wake patterns that form in the flows around finite wings. Among others, we can pinpoint the wing tip vortex, the separation region that develops under adverse pressure gradient, and the coherent vortical structures. Thanks to these past efforts, we were able to significantly extend our knowledge in aerodynamics, which paved the way for an impressive evolution of aircraft designs in the last century. Over the years, commercial flight became an ordinary asset in our society. More recently, small and micro air vehicles have also reached the market, being operated by individuals who hold no necessary knowledge of the complexity of the Navier-Stokes equations. The advanced knowledge currently held on flight physics has played a fundamental role in the development of aircraft designs, however, there is still room for improvement. In post-stall flow conditions, the aerodynamic performance of the wing decays considerably, making it challenging to sustain flight at high incidence angles. To enable flight in such flow conditions, it is important to develop physics-based flow control strategies capable of improving the overall aerodynamic performance of the wing and its flight stability. The main implications are reduced fuel (and energy) consumption during flight, increased aircraft range, improvements in safety and productivity of air travel, attenuation of the acoustic signature, as well as enabled capability of aircraft to fly in challenging external environments. Towards this goal, many studies have been performed to analyze and control flows over airfoils in spanwise periodic configurations. These may also be called infinite-span wings. These studies were fundamental to revealing important aspects of flow physics. However, in reality, the flows around wings are three-dimensional (3-D). In addition, modern aircraft wings are usually tapered and swept. The 3-D vortex dynamics of flows over wings has a significant influence on aircraft design, by reducing the overall lift, generating induced drag, and increasing flow unsteadiness. Thus, it is important to develop strategies to control the vortex dynamics that encompass the knowledge of the 3-D characteristics of the flow over finite, swept, and tapered wings. Especially for post-stall flow conditions, the wake dynamics around tapered swept wings is largely unexplored. It is still a challenge to understand how the wing geometry relates to the vortex formation for different aspect and taper ratios, as well as angles of attack and sweep. To design control strategies to improve aerodynamic performance for finite, swept, and tapered wings, we must go beyond the sole characterization of flow structures. In fact, the identification of perturbation dynamics is called for to modify the flow field. Three-dimensional flow control is challenging due to the high-dimensional and nonlinear nature of the flow dynamics of the wakes. Thus, it is necessary to find an appropriate actuation setup for the problem that can alter the base flow behavior. This effort can be guided by modal analysis methods. In our work, we have used resolvent analysis, a method based on the singular value decomposition (SVD) of the resolvent, which is a linear operator constructed using the Navier-Stokes equations linearized with respect to the base flow. For unsteady flows, the statistically converged time-averaged flow field is used as a base flow to construct the resolvent operator. The strength of the resolvent operator through this approach is the capability to find optimal forcing modes which amplify outputs in the flow field and give insights into the perturbed flow through the spatial response modes. The challenge within resolvent analysis is the SVD computation for large-scale resolvent operators that are generated for high-dimensional flow fields, such as three-dimensional and turbulent flows. By taking advantage of low-rank approximation of the resolvent operator, recent developments using randomized numerical linear algebra have accelerated the computation of the dominant resolvent modes. With reduced computational costs, these efforts have enabled the use of resolvent analysis in turbulent flows over spanwise periodic airfoils and expanded its applicability to triglobal problems and higher Reynolds number flows. With the randomized algorithm, we can use resolvent analysis to uncover the dynamics of 3-D flows over finite, swept, and tapered wings, supporting flow control efforts to improve their overall aerodynamic performance. The present study has shown how to develop a 3-D resolvent-based flow control over finite wings. We initiate by studying flows over finite wings and the effects of wing sweep and taper on the post-stall wake dynamics through direct numerical simulations (DNS). We consider laminar flows at chord-based Reynolds numbers of 400 and 600 with weak compressible effects at a freestream Mach number 0.1. The flows are studied around wings at angles of attack between 14 and 30 degrees with semi aspect ratios ranging from 1 to 4, sweep angles up to 50 degrees, and taper ratios from 0.27 to 1. Following a comprehensive characterization of the wake dynamics through DNS results, we extend our knowledge of the dynamics of flow perturbations by analyzing the triglobal resolvent modes. Through the identification of the optimal harmonic perturbations that can be amplified in the flow field, we develop 3-D active flow control that is shown to significantly modify the wake structures around the wings. This comprehensive investigation provides novel and unique insights that reveal the flow structures that can be amplified in the wake and modify their dynamics in post-stall flow conditions.
Book Synopsis Handbook of Wind Energy Aerodynamics by : Bernhard Stoevesandt
Download or read book Handbook of Wind Energy Aerodynamics written by Bernhard Stoevesandt and published by Springer Nature. This book was released on 2022-08-04 with total page 1495 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook provides both a comprehensive overview and deep insights on the state-of-the-art methods used in wind turbine aerodynamics, as well as their advantages and limits. The focus of this work is specifically on wind turbines, where the aerodynamics are different from that of other fields due to the turbulent wind fields they face and the resultant differences in structural requirements. It gives a complete picture of research in the field, taking into account the different approaches which are applied. This book would be useful to professionals, academics, researchers and students working in the field.
Book Synopsis Flow Visualization Studies of the Mach Number Effects on the Dynamic Stall of an Oscillating Airfoil by : M. Chandrasekhara
Download or read book Flow Visualization Studies of the Mach Number Effects on the Dynamic Stall of an Oscillating Airfoil written by M. Chandrasekhara and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Three-Dimensional Flow in the Root Region of Wind Turbine Rotors by : Galih Bangga
Download or read book Three-Dimensional Flow in the Root Region of Wind Turbine Rotors written by Galih Bangga and published by kassel university press GmbH. This book was released on 2018-06-20 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the state of the art in the analyses of three-dimensional flow over rotating wind turbine blades. Systematic studies for wind turbine rotors with different sizes were carried out numerically employing three different simulation approaches, namely the Euler, URANS and DDES methods. The main mechanisms of the lift augmentation in the blade inboard region are described in detail. The physical relations between the inviscid and viscous effects are presented and evaluated, emphasizing the influence of the flow curvature on the resulting pressure distributions. Detailed studies concerning the lift augmentation for large wind turbine rotors are considered as thick inboard airfoils characterized by massive separation are desired to stronger contribute to power production. Special attention is given to the analyses of wind turbine loads and flow field that can be helpful for the interpretation of the occurring physical phenomena. The book is aimed at students, researchers, engineers and physicists dealing with wind engineering problems, but also for a wider audience involved in flow computations.
Book Synopsis Wind Energy Explained by : James F. Manwell
Download or read book Wind Energy Explained written by James F. Manwell and published by John Wiley & Sons. This book was released on 2010-09-14 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind energy’s bestselling textbook- fully revised. This must-have second edition includes up-to-date data, diagrams, illustrations and thorough new material on: the fundamentals of wind turbine aerodynamics; wind turbine testing and modelling; wind turbine design standards; offshore wind energy; special purpose applications, such as energy storage and fuel production. Fifty additional homework problems and a new appendix on data processing make this comprehensive edition perfect for engineering students. This book offers a complete examination of one of the most promising sources of renewable energy and is a great introduction to this cross-disciplinary field for practising engineers. “provides a wealth of information and is an excellent reference book for people interested in the subject of wind energy.” (IEEE Power & Energy Magazine, November/December 2003) “deserves a place in the library of every university and college where renewable energy is taught.” (The International Journal of Electrical Engineering Education, Vol.41, No.2 April 2004) “a very comprehensive and well-organized treatment of the current status of wind power.” (Choice, Vol. 40, No. 4, December 2002)
Book Synopsis Wind Energy in the 21st Century by : R. Redlinger
Download or read book Wind Energy in the 21st Century written by R. Redlinger and published by Springer. This book was released on 2016-01-22 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind energy is the great success story of modern renewable energy. Since the industry's rebirth following the energy crisis of the 1970s, thousands of wind energy projects have been installed around the world. The technology today is competitive with traditional fossil-fuelled electricity generation. Wind Energy in the 21st Century explores the current economic, financial, technical, environmental, competitive, and policy considerations facing the wind energy industry. With discussions of the latest electricity industry trends including deregulation, green markets, and tradable renewable credits, this book is a must-read for energy policymakers, researchers, and energy industry professionals.
Book Synopsis The Effect of Trailing Vortices on the Production of Lift on an Airfoil Undergoing a Constant Rate of Change of Angle of Attack by : K. W. Tupper
Download or read book The Effect of Trailing Vortices on the Production of Lift on an Airfoil Undergoing a Constant Rate of Change of Angle of Attack written by K. W. Tupper and published by . This book was released on 1983 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study was to investigate the effect a trailing vortex wake has on an airfoil undergoing a constant rate of change of angle of attack, alpha, in two-dimensional, incompressible, irrotational flow. Potential flow theory, conformal mapping by the Joukowski transformation, and numerical integration and differentiation techniques were used to develop a computer algorithm to model the problem. Once the program was formulated, it was used to solve the impulsive-start problem of airfoil motion. The results were found to be in excellent agreement with the results obtained by others. When applied to the constant rate-of-change of angle-of-attack problem, the results showed that a trailing vortex wake has a measurable and predictable effect on the production of lift on an airfoil undergoing a constant alpha. While results of this work, taken alone, are helpful in understanding the phenomena known as dynamic stall, coupled with existing boundary-layer studies the results may lead to additional understanding of the phenomena. More specifically, the computer program develop here could be used to predict more realistically the inviscid flow about a pitching airfoil as it approaches the dynamic-stall conditions.
Book Synopsis Low Reynolds Number by : Mustafa Serdar Genç
Download or read book Low Reynolds Number written by Mustafa Serdar Genç and published by BoD – Books on Demand. This book was released on 2012-04-04 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports the latest development and trends in the low Re number aerodynamics, transition from laminar to turbulence, unsteady low Reynolds number flows, experimental studies, numerical transition modelling, control of low Re number flows, and MAV wing aerodynamics. The contributors to each chapter are fluid mechanics and aerodynamics scientists and engineers with strong expertise in their respective fields. As a whole, the studies presented here reveal important new directions toward the realization of applications of MAV and wind turbine blades.
Book Synopsis Investigation of Airfoil Boundary Layer and Turbulent Wake Development at Low Reynolds Numbers by : Serhiy Yarusevych
Download or read book Investigation of Airfoil Boundary Layer and Turbulent Wake Development at Low Reynolds Numbers written by Serhiy Yarusevych and published by . This book was released on 2006 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boundary layer and wake development on a NACA 0025 airfoil at low Reynolds numbers was studied experimentally via surface pressure measurements, hot-wire velocity measurements, and flow visualization. Wind tunnel experiments were carried out for a range of Reynolds numbers and three angles of attack. In addition, flow control with periodic excitations was investigated and a shear layer stability analysis was performed. Two boundary layer flow regimes were identified: (1) boundary layer separation without reattachment and (2) separation bubble formation. The results have demonstrated that transition to turbulence, which occurs due to the amplification of disturbances in the separated shear layer, plays a key role in boundary layer reattachment. Once disturbances reach sufficient amplitude, shear layer roll-up occurs and the resulting vortices are shed at a fundamental frequency. The roll-up process is attributed to the Kelvin-Helmholtz instability, and the salient characteristics of the roll-up vortices can be adequately estimated by means of inviscid linear stability analysis. The final stage of transition is associated with the growth of a sub-harmonic component in the velocity spectrum, which can be attributed to the merging of the roll-up vortices. Wake vortices form in the near-wake region and are shed alternatively on the upper and lower sides of the turbulent wake. Each of the two identified flow regimes is associated with distinctly different characteristics of both the roll-up and wake vortices. It has been established that the fundamental frequency of the shear-layer disturbances exhibits a power law dependency on the Reynolds number, whereas the wake vortex shedding frequency displays a linear dependency on the Reynolds number. A universal scaling for the wake vortex shedding frequency has been determined, which has a universal Strouhal number of 0.17. The results provide added insight into flow control with external acoustic excitation. It is concluded that matching the excitation frequency with the frequency of the most amplified disturbance in the separated shear layer is the optimum method for controlling airfoil performance. Two threshold levels for excitation amplitude have been identified: (i) a minimum effective amplitude that is linked to the background noise level and (ii) a maximum efficient amplitude.
Book Synopsis Advances in Wind Turbine Blade Design and Materials by : Povl Brondsted
Download or read book Advances in Wind Turbine Blade Design and Materials written by Povl Brondsted and published by Elsevier. This book was released on 2013-10-31 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind energy is gaining critical ground in the area of renewable energy, with wind energy being predicted to provide up to 8% of the world’s consumption of electricity by 2021. Advances in wind turbine blade design and materials reviews the design and functionality of wind turbine rotor blades as well as the requirements and challenges for composite materials used in both current and future designs of wind turbine blades. Part one outlines the challenges and developments in wind turbine blade design, including aerodynamic and aeroelastic design features, fatigue loads on wind turbine blades, and characteristics of wind turbine blade airfoils. Part two discusses the fatigue behavior of composite wind turbine blades, including the micromechanical modelling and fatigue life prediction of wind turbine blade composite materials, and the effects of resin and reinforcement variations on the fatigue resistance of wind turbine blades. The final part of the book describes advances in wind turbine blade materials, development and testing, including biobased composites, surface protection and coatings, structural performance testing and the design, manufacture and testing of small wind turbine blades. Advances in wind turbine blade design and materials offers a comprehensive review of the recent advances and challenges encountered in wind turbine blade materials and design, and will provide an invaluable reference for researchers and innovators in the field of wind energy production, including materials scientists and engineers, wind turbine blade manufacturers and maintenance technicians, scientists, researchers and academics. 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 energy production
