Реферат: Wind Power Essay Research Paper The wind

altitude. In calculating how high a windmill should be the following

equation is used: V1/V2 = (H1/H2)n, Where V1 is the wind speed at the

highest point of the highest blade, V2 is the wind speed at the lowest

point of the lowest blade, H1 is the height of the highest point, and H2

is the height of the lowest point. n is the index location of the site, a

va lue that measures the roughness of the terrain.

The structures, aerofoils (see also vector diagrams, attached)

The support of the windmill is generally made out of steel. The

windshaft is the shaft which carries the windwheel or aerofoils. It is

turned as the aerofoils turn. It is made of steel or wood.

Aerofoils are the blades on a windmill. They can be made out of

any material. They were first made of wood or wood composites. Steel was

used after that. Aluminum is used in the Darrieus windmills because it is

much stronger. Unfortunately, Aluminum fatigues quicker. Some windmills

use fiberglass blades. New materials such as strong alloys are being used

in today’s windmills experimentally. It is important that the blades have

a large lift force and a small drag force. The lift force is the force

needed to bend the flow of the (fluid) air. It is the force perpendicular

to the stream of the air. The drag force is the force parallel to the

stream. The aerofoil must be able to develop a lift force at least 50

times greater than the drag. Torque acts on the aerofoil with a vector

from the center of rotation away. Other forces that act on the blades of

windmills are wind shears, wind gusts, which push on the aerofoils,

gravity, a pull towards the earth, and shifts in the direction of the

wind. Shifts in the direction of the wind are often accounted for by

having a

small blade, called a tailvane, on the backside of a windmill. The wind

blows on a flat side of the tail, which is oriented differently from the

aerofoils. Then, the aerofoils can be rotated to face into the wind. If