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2020 | Buch

Kapitel lesen Erstes Kapitel lesen

Introduction to Wind Turbine Aerodynamics

verfasst von: Prof. Dr. A. P. Schaffarczyk

Verlag: Springer International Publishing

Buchreihe : Green Energy and Technology

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

This book offers an introduction to the topic for professionals and students with a diverse range of backgrounds. Wind Turbine Aerodynamics is a self-contained textbook that shows how to progress from the basics of fluid mechanics to modern wind turbine blade design. It presents the fundamentals of fluid dynamics and inflow conditions, as well as extensive information on theories describing the aerodynamics of wind turbines. After examining a number of related experiments, the book applies the lessons learned to blade design.

The text of the 2nd edition has been thoroughly revised, with a focus on improved readability. The examples and solutions have been extended to explain each problem in much greater detail.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

Wind energy has been used for a long time. Chap. 1 of [2] gives a short account of this history and describes the first scientific approaches. It is immediately seen that even this applied branch of fluid mechanics suffers from a general malady: Prior to the twentieth century, mathematical descriptions and practical needs were far removed from one another.

A. P. Schaffarczyk

Chapter 2. Types of Wind Turbines

Abstract

Equation (1.5) from Chap. 1 may also be used to define an efficiency or power coefficient $0 \le c_P \le 1$:

$$\begin{aligned} c_P = \frac{P}{\frac{\rho }{2} A_r \cdot v^3} \; . \end{aligned}$$

Wind turbine aerodynamic analysis frequently involves the derivation of useful equations and numbers for this quantity.

A. P. Schaffarczyk

Chapter 3. Basic Fluid Mechanics

Abstract

Air regarded as an ideal gas may be described by its mass–density $\rho = dm/dV$. To adjust its standard value of $\rho _0 = 1.225\;\mathrm{kg/m}^3$ to other temperatures ($\vartheta $) and elevations (H) we may use $ \rho (p,T) = \frac{p}{R_i \cdot T} T = 273.15 + \vartheta R_i = 287 p(z) = p_0 \cdot e^{-z/z_{ref}} p_0 = 1015 \;\mathrm{hPa} z_{ref} = 8400 \;\mathrm{m}.$

A. P. Schaffarczyk

Chapter 4. Inflow Conditions to Wind Turbines

Abstract

In Chap. 3 some of the necessary fluid mechanics background was introduced. Now looking closer at the wind turbine, we may ask which details of the turbulent wind field are generally more important and in which order the properties of this field should be discussed. Certainly one may start with the easiest flow field: a spatially and temporally constant one. This model is used in most analytical studies.

A. P. Schaffarczyk

Chapter 5. Momentum Theories

Abstract

In the meantime, several relevant textbooks have been published:

Reference [38] summarizes advances in momentum theory with special emphasis on connection to vortex theory and compares Joukovskie’s and Betz’ Vortex model.
Reference [5] starts from vorticity-based methods and gives a very detailed compilation of applications to wind turbine aerodynamics.
Reference [20] discusses the path from basic (Euler’s) differential equations to the Actuator Disk model.
Reference [8] in Chap. 1 this most recent book gives a self-contained basis for design. Special emphasis is given to various approaches to aerodynamical design.

A. P. Schaffarczyk

Chapter 6. Application of Vortex Theory

Abstract

It was already mentioned in Chap. 3 that Saffman (Vortex dynamics, 1992, [27]) quoted Küchemann, who said that

vortices are the sinews and muscles of fluid motion.

A. P. Schaffarczyk

Chapter 7. Application of Computational Fluid Mechanics

Abstract

As we have seen in the previous chapters, due the nonlinear behavior it is very difficult—if not impossible—to get simple analytical solutions of the basic fluid dynamic equations in a systematic way. Therefore, it has become normal to use (massive) numerical methods for solving them. In an ideal situation this would mean that only the Eqs. (3.37) from Chap. 3 are used (of course adapted to a suitable form for computers) together with a geometrical description of the problem (a wind turbine wing, for example) and a surrounding control volume for setting the boundary conditions for the unknown fields (pressure and velocity).

A. P. Schaffarczyk

Chapter 8. Experiments

Abstract

As we have explained extensively in the previous chapters the blade-element-momentum method describes blades—aerodynamically—as a set of independent 2D airfoils. Therefore, wind tunnel measurement of 2D sections is the basis of all aerodynamical experiments for wind turbines. Fortunately, a lot of experience has been gained for airfoils of airplanes which could be used when special airfoils started to be designed [33] in Chap. 9.

A. P. Schaffarczyk

Chapter 9. Impact of Aerodynamics on Blade Design

Abstract

Now having introduced all knowledge from fluid mechanics, it is high time to try to give an overview on what is really used in practical wind turbine blade design. Referring to Chap. 10 and especially Fig. 10.1 we see that with the development of huge offshore wind turbines up to 170 m rotor diameter, a period of exponential growth has started again after some years of dormancy.

A. P. Schaffarczyk

Chapter 10. Concluding Remarks on Further Developments

Abstract

In this book, we have tried to give an overview of aerodynamics of wind turbines and its application to blade design. During the last few decades rotor size (see Fig. 10.1) increased more than one order of magnitude (exponentially). After a five-year period of stagnation, starting in 2010 there seems to be exponential rotor size growth occurring again culminating so far with design and construction of 2220 m diameter 12 MW offshore wind turbine.

A. P. Schaffarczyk

Backmatter

Titel: Introduction to Wind Turbine Aerodynamics
verfasst von: Prof. Dr. A. P. Schaffarczyk
Verlag: Springer International Publishing
Electronic ISBN: 978-3-030-41028-5
Print ISBN: 978-3-030-41027-8
DOI: https://doi.org/10.1007/978-3-030-41028-5