Page 10 - Fluid Power Engineering
P. 10
viii Contents
Relative Velocity of Wind .................. 44
Rotor Disk Theory ...................... 47
Lift Force ............................ 51
Equal Transit Time Fallacy .............. 51
Rotation Fluid Flow, Circulation, and Vortices .. 51
Real Fluids ........................ 55
Flow of Fluid over an Airfoil ............. 56
Effect of Reynolds Number on Lift and Drag
Coefficients ...................... 58
Drag-Based Turbines .................... 59
5 Advanced Aerodynamics of Wind Turbine Blades . 63
Introduction .......................... 63
Blade Element Model .................... 63
Constant-Speed Turbines, Stall-versus
Pitch-Regulated ...................... 68
Variable-Speed Turbines .................. 70
Power Curves ......................... 70
Vertical Axis Wind Turbine (VAWT) ........... 72
6 Wind Measurement ..................... 75
Introduction .......................... 75
Definition of Wind Speed .................. 75
Configurations to Measure Wind ............. 76
Anemometer ....................... 77
Calibration of Anemometers ............. 81
Wind Vane ........................ 81
Placement of Sensors .................. 82
Impact of Inflow Angle ................ 85
Impact of Temperature ................. 85
Uncertainty in Wind Speed Measurement
with Anemometers ................. 85
Example of Error Estimate .............. 88
Other Sensors ...................... 89
Data Logger and Communication Device ..... 89
Designing a Wind Measurement Campaign ...... 90
Installation of Met-Towers ................. 93
Example of Met-Tower Installation ............ 94
Data Management ...................... 94
Data Processing ........................ 96
Computed Quantities .................... 101
Turbulence ........................ 101
Wind Shear ........................ 103
Air Density ........................ 104
Power Density ...................... 105
