Dissertation•
Development of Free Vortex Wake Method for Aerodynamic Loads on Rotor Blades
TL;DR: In this article, a free vortex wake method, based on the potential, invisciduity and irrotational flow, is developed to study the aerodynamic load of wind turbines.
Abstract: The aerodynamics of a wind turbine is governed by the flow
around the rotor, where the prediction of air loads on rotor
blades in different operational conditions and its relation to rotor structural dynamics is crucial for design purposes. One of the most important challenges in wind turbine aerodynamics is therefore to accurately predict the forces on the blade, where the blade and wake are modeled by different approaches such as the Blade Element Momentum (BEM) theory, the vortex method and Computational Fluid Dynamics (CFD).
A free vortex wake method, based on the potential, inviscid
and irrotational flow, is developed to study the aerodynamic
loads. The results are compared with the BEM method,
the GENUVP code and CFD.
Citations
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TL;DR: The hybrid RANS-LES method (HRLM) as mentioned in this paper is a technique to bridge the gap between less accurate RANS and more computational costly LES method, which is a remedy to turbine aerodynamics in complex flow conditions.
112 citations
01 Jan 2020
TL;DR: This course material was used in two courses in the Internatio l Master's program of applied mechanics at Chalmers as discussed by the authors, TME225 Mechanics of fluids, and MTF270 Turbulence Modeling.
Abstract: This course material is used in two courses in the Internatio l Master’s programmeApplied Mechanicsat Chalmers. The two courses are TME225 Mechanics of fluids, andMTF270 Turbulence Modeling . MSc students who follow these courses are supposed to have taken one basic course in fluid me chanics. This document can be downloaded at http://www.tfd.chalmers.se/ ̃lada/MoF/lecture notes.html
53 citations
TL;DR: In this paper, the first steps of development and validation of a CFD tool dedicated to realistic tidal turbine farm modelling are presented, together with the actuator disc model used to represent tidal turbines.
20 citations
TL;DR: Some of the necessary adaptations of the nonlinear Lifting Line Free Vortex Wake code are described, which differentiates it from the usual application in HAWT simulations, set on achieving a high robustness and computational efficiency.
Abstract: Recently a new interest in vertical axis wind turbine (VAWT) technology is fueled by research on floating support structures for large scale offshore wind energy application For the application on floating structures at multi megawatt size, the VAWT concept may offer distinct advantages over the conventional horizontal axis wind turbine (HAWT) design As an example VAWT turbines are better suited for upscaling and, at multi megawatt size, the problem of periodic fatigue cycles reduces significantly due to a very low rotational speed Additionally, the possibility to store the transmission and electricity generation system at the bottom, compared to the tower top as in a HAWT, can lead to a considerable reduction of material logistics costs However, as most VAWT research stalled in the mid 90’s, no established and sophisticated tools to investigate this concept further exist today Due to the complex interaction between unsteady aerodynamics and movement of the floating structure fully coupled simulation tools, modelling both aero and structural dynamics are needed A nonlinear Lifting Line Free Vortex Wake code was recently integrated into the open source wind turbine simulation suite QBlade This paper describes some of the necessary adaptations of the algorithm, which differentiates it from the usual application in HAWT simulations A focus is set on achieving a high robustness and computational efficiency A short validation study compares simulation results with those of a U-RANS and a Double Multiple Streamtube (DMS) simulation
18 citations
TL;DR: In this article, a new aerodynamic module, called AeroVIEW (Aerodynamic Vortex fIlament Wake) based on an implementation of the Free Vortex filament Method (FVM) combined with an unsteady Lifting Line (LL), is presented.
11 citations
References
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01 Feb 2009
TL;DR: In this article, a three-bladed, upwind, variable speed, variable blade-pitch-to-feather-controlled multimegawatt wind turbine model developed by NREL to support concept studies aimed at assessing offshore wind technology is described.
Abstract: This report describes a three-bladed, upwind, variable-speed, variable blade-pitch-to-feather-controlled multimegawatt wind turbine model developed by NREL to support concept studies aimed at assessing offshore wind technology.
4,194 citations
Book•
01 Feb 1986
TL;DR: In this article, Navier-Stokes et al. discuss the fundamental principles of Inviscid, Incompressible Flow over airfoils and their application in nonlinear Supersonic Flow.
Abstract: TABLE OF CONTENTS Preface to the Fifth Edition Part 1: Fundamental Principles 1. Aerodynamics: Some Introductory Thoughts 2. Aerodynamics: Some Fundamental Principles and Equations Part 2: Inviscid, Incompressible Flow 3. Fundamentals of Inviscid, Incompressible Flow 4. Incompressible Flow Over Airfoils 5. Incompressible Flow Over Finite Wings 6. Three-Dimensional Incompressible Flow Part 3: Inviscid, Compressible Flow 7. Compressible Flow: Some Preliminary Aspects 8. Normal Shock Waves and Related Topics 9. Oblique Shock and Expansion Waves 10. Compressible Flow Through Nozzles, Diffusers and Wind Tunnels 11. Subsonic Compressible Flow Over Airfoils: Linear Theory 12. Linearized Supersonic Flow 13. Introduction to Numerical Techniques for Nonlinear Supersonic Flow 14. Elements of Hypersonic Flow Part 4: Viscous Flow 15. Introduction to the Fundamental Principles and Equations of Viscous Flow 16. A Special Case: Couette Flow 17. Introduction to Boundary Layers 18. Laminar Boundary Layers 19. Turbulent Boundary Layers 20. Navier-Stokes Solutions: Some Examples Appendix A: Isentropic Flow Properties Appendix B: Normal Shock Properties Appendix C: Prandtl-Meyer Function and Mach Angle Appendix D: Standard Atmosphere Bibliography Index
3,113 citations
"Development of Free Vortex Wake Met..." refers background in this paper
...Theory Vortex flow theory is based on assuming incompressible (∇ ·V = 0) and irrotational ( ∇×V = 0) flow at every point except at the origin of the vortex, where the velocity is infinit e [10]....
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05 Feb 2001
TL;DR: In this article, a modern treatment of the subject, both the theory of inviscid, incompressible, and irrotational aerodynamics and the computational techniques now available to solve complex problems is presented.
Abstract: Low-speed aerodynamics is important in the design and operation of aircraft flying at low Mach number, and ground and marine vehicles. This 2001 book offers a modern treatment of the subject, both the theory of inviscid, incompressible, and irrotational aerodynamics and the computational techniques now available to solve complex problems. A unique feature of the text is that the computational approach (from a single vortex element to a three-dimensional panel formulation) is interwoven throughout. Thus, the reader can learn about classical methods of the past, while also learning how to use numerical methods to solve real-world aerodynamic problems. This second edition has a new chapter on the laminar boundary layer (emphasis on the viscous-inviscid coupling), the latest versions of computational techniques, and additional coverage of interaction problems. It includes a systematic treatment of two-dimensional panel methods and a detailed presentation of computational techniques for three-dimensional and unsteady flows. With extensive illustrations and examples, this book will be useful for senior and beginning graduate-level courses, as well as a helpful reference tool for practising engineers.
1,810 citations
"Development of Free Vortex Wake Met..." refers methods in this paper
...The vortex lattice method (VLM) is based on the thin lifting surface theory of vortex ring elements [16], where the bl ade surface is replaced by vortex panels that are constructed ba sed on the airfoil camber line of each blade section (see fig....
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Book•
01 Jan 2001
TL;DR: In this article, the authors present a detailed review of the aerodynamics of wind turbines with respect to structural dynamics and control, including a new control chapter that includes details on how to design a classical pitch and torque regulator to control rotational speed and power.
Abstract: Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design a classical pitch and torque regulator to control rotational speed and power, while the section on structural dynamics has been extended with a simplified mechanical system explaining the phenomena of forward and backward whirling modes. Readers will also benefit from a new chapter on Vertical Axis Wind Turbines (VAWT).
Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method is also covered, as are eigenmodes and the dynamic behaviour of a turbine.
The book describes the effects of the dynamics and how this can be modelled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Furthermore, it examines how to calculate the vibration of the whole construction, as well as the time varying loads and global case studies.
1,192 citations
"Development of Free Vortex Wake Met..." refers background or methods in this paper
...Compared with the BEM method, the vortex method is able to provide more physical solutions for attached flow cnditions using boundary layer corrections, and it is also valid over a wider range of turbine operating conditions....
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...: BEM, : GENUVP Figure (10) shows the geometric and the effective angle of attack along the blade....
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...The results of the vortex lattice free wake model (VLFW) are compared with the BEM method, GENUVP code and CFD....
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...Since the vortex method (VLFW and GENUVP) is a potential flow (no viscous drag), it predicts more power than the BEM and CFD methods....
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...As we know, : CFD, : VLFW, : BEM, : GENUVP the generated power of a wind turbine is computed on the basisof the tangential force....
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TL;DR: In this article, the aerodynamic properties of wind turbine wakes are studied, focusing on the physics of power extraction by wind turbines, and the main interest is to study how the far wake decays downstream in order to estimate the effect produced in downstream turbines.
1,161 citations
"Development of Free Vortex Wake Met..." refers background in this paper
...A number of empirical and semi-empirical co rrection factors have been added to the BEM in order to increas e its application range, such as yaw misalignment, dynamic in flow, dynamic stall, tower influence, finite number of blades and bl a e cone angle [4], but they are not relevant to all operating con ditions and are often incorrect at high tip speed ratios where w ake distortion is significant [5]....
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