1. Wind Turbine

2. Wind Turbine Size-Power Comparison

3. Wind Turbine Configurations
HAWT
VAWT
Boyle, G., Renewable Energy, 2nd ed., Oxford University Press, 2004

4. Configuration Tradeoffs
Factors
Efficiency
Power produced per unit cost
Directionality
Support configuration
Speed of rotation
Reliability
Cost
Maintainability
Which type is best, HAWT or VAWT?

5. Common HAWT Construction
Rotor
Blades are connected to a hub, which is connected to a shaft
Rotational speed will depend on blade geometry, number of blades, and wind speed (40 to 400 revolutions per minute typical speed range)
Gear box needed to increase speed to RPM for generator

6. Aerodynamics of Wind Turbine Blades
Forces are transmitted from a moving fluid to an object in the flow stream
Lift = the force component perpendicular to the original flow direction
Drag = the force component in line with the original flow direction
Lift
Drag

7. Two Types of Turbine Designs
Drag Designs
Savonius
Lift Designs
VAWT Darrieus
Most HAWT designs

8. Aerodynamics of HAWT Blade
r[L(sinf) - D(cosf)] = Torque
Torque x rotational speed= Power
Boyle, G., Renewable Energy, 2nd ed., Oxford University Press, 2004

9. Aerodynamics of HAWT Blade, cont.
Angle of attack, a (blade angle between chord and relative wind direction)
Has a large effect on the lift and drag
Typical values between 1 and 15 degrees (what is optimum?)

10. Design of HAWT Turbine Blade
Blade size and shape
5-station design as seen from the tip
The blade twists to keep angle of attack constant

11. Design of HAWT Turbine Blade, cont.
Number of blades
Increasing the number of blades tends to increase the aerodynamic efficiency
Increasing the number of blades increases the cost (material and manufacturing
Turbines with fewer blades tend to run most efficiently at lower tip speed ratios (ratio of tip speed to wind speed)