10-05-2012, 04:17 PM
Wind Power and Wind Turbines
WindPowerWindTurbines.ppt (Size: 2.78 MB / Downloads: 251)
Wind – what causes it?
Pressure maps
Contours of constant pressure (usually 4 mb between contours
Close spacing means stronger winds
In N.H., winds circulate around a low pressure region in CCW direction
Atmospheric pressure differences accelerate and impart kinetic energy into the air
Wind energy conversion machines (WEC) convert wind energy into electrical or mechanical forms
How much power can we extract?
Common HAWT Construction
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 1200-1800 RPM for generator
Design of HAWT Turbine Blade
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 efficientlyat lower tip speed ratios(ratio of tip speed to wind speed)