Homebuilt Wind Turbine Explained

 

 

 

 

Wind Vane

A wind vane a.k.a weather vane is used to measure wind direction. The wind vane is attached to the controller and communicates the wind direction via a small sensor to the wind turbine controller. A wind vane is always positioned according to the direction of wind. A weather vane always positions itself according to the wind direction. A wind vane can be notifying the wind direction to some attached instrument, like a wind turbine ,or it can be a standalone version that is read off by the naked eye.

In the case of when a weather vane is attached to a wind turbine, it notifies the controller about wind speed and direction. The controller in turn tells the yaw motor to turn the nacelle so that the rotor faces the wind. The photo to the left shows an anemometer in combination with a wind vane. This type is called cup-anemometer.

Anemometers

The anemometer is what makes it possible for the wind vane to measure both wind speed and direction Anemometer comes from the word anemos and is Greek for wind. Nowadays the anemometer is an electrical device that calculates the wind velocity but that hasn't always been the case, they used to be of the mechanical kind.

The first mechanical anemometer was invented in 1450 by a man named Leon Battista Alberti. It consisted of a disk that rotated by the force of the wind. Later on an Englishman by the name of Robert Hooke re-invented the anemometer and is often mistakenly believed to be the inventor of this instrument.

Anemometers can be divided in two classes, there are those that measure the velocity of the wind and there are those that measure the pressure of the wind. A high quality and modern anemometer will give information about both of these quantities. Down below there is a list of anemometers that reaches the same goal by using different technologies.

Velocity anemometers:

• Cup anemometers
  The simplest kind of them all and invented in 1846 by John Thomas Romney Robinson of Armagh Observatory
• Hot-wire anemometers
  This type uses a fine wire heated up to some temperature above the ambient. When the wind flows past the wire and cools the wire down a relationship can be obtained and a calculation produces correct data.
• Laser Doppler anemometers
  Uses a laser beam to measaure the wind speed and direction.
• Sonic anemometers
  Uses sound waves to measure wind speed and direction.
• Windmill anemometers
  These are the kind that is attached to a wind mills.

Pressure anemometers:

• Plate anemometers
  This is the simplest type of pressure anemometers and consists of a circular or square faced into the wind. This kind of instrument is not the most accurate.
• Tube anemometers

Anemometer