Page 9 - Fluid Power Engineering

Contents

Preface .............................. xiii
Acknowledgments ....................... xvii
1 Overview of Wind Energy Business .......... 1
Introduction .......................... 1
Worldwide Business of Wind Energy .......... 1
Cost of Wind Energy ..................... 4
Benefits of Wind Energy .................. 4
Wind Energy Is Not a Panacea .............. 6

2 Basics of Wind Energy and Power ............ 9
Introduction .......................... 9
Kinetic Energy of Wind ................... 9
Sensitivity of Power to Rotor Radius
and Wind Speed ...................... 11
Basic Concepts/Equations ................. 12
Conservation of Mass .................... 12
Conservation of Energy ................... 13
Conservation of Momentum ................ 14
Derivation of Betz Limit .................. 16
The Meaning of Betz Limit ................. 20
Wind versus Water ...................... 22
3 Properties of Wind ..................... 25
Introduction .......................... 25
How Is Wind Generated? .................. 25
Statistical Distribution of Wind Speed .......... 26
Mean and Mode of Weibull Distribution
for Wind Speed .................... 29
Power Density ........................ 30
Wind Classes ......................... 31
Wind Shear ........................... 33
Understanding Wind Shear .............. 36
Density of Air as a Function of Elevation ........ 37
Density of Air as a Function of Humidity ..... 39
4 Aerodynamics of Wind Turbine Blades ........ 41
Introduction .......................... 41
Airfoils ............................. 41

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