Basics of A Wind Power Turbine

Amongst the various alternative energy sources that are available to us today, wind energy figures as one of the most widely harnessed resource, thanks to the availability of wind power turbines. Essentially a wind power turbine is a rotary devise, which converts the kinetic energy of the wind into mechanical energy. This mechanical energy can be further used to generate electricity, which can then be used for a variety of purposes, be it agricultural, industrial or domestic.

A wind power turbine can alternatively be referred to as a wind generator, wind power unit (WPU), wind energy converter (WEC) or an aerogenerator. Normally wind power turbines are classified under two broad categories: -

Horizontal Axis Wind Turbines – These turbines rotate around a given horizontal axis and are commonly used. They comprise of a rotor shaft and an electrical generator placed near the top of the tower pointing into the wind. A wind vane can be used for smaller turbines while some large turbines involve the use of a wind sensor joined to a servomotor.

The turbine blades are made rigid in order to prevent them from colliding with the tower during strong wind conditions. The blades are also placed at a suitable distance from the tower and sometimes tilted in the upward direction. Turbulence is a big problem thus most horizontal axis wind turbines are built as upwind machines.

Wind turbines have been in existence from centuries and some popular types of horizontal axis wind turbine machines are listed below for your reference:

• Windmills from the early 12th century are a typical example, which consisted of four blades and were directed into the wind manually or through tail fans and were generally used for grinding grains.
• Windmill from late 19th century had many blades and were coupled with DC generators to power small batteries, provide lighting or can power a standard radio receiver. These windmills are still operational in places where setting up commercial power stations is not feasible.
• Modern wind power turbines, usually consisting of 3 blades are directed into the wind by computerized motors. They have significantly high tip speeds, are more efficient with a low torque ripple and are extremely reliable. They can automatically shut down to avoid damage during high wind speeds.

Vertical Axis Wind Turbines (VAWT) – These turbines have a vertically aligned main rotor shaft and there biggest advantage is that they don’t need to be pointed in the direction of the wind to be effective. This enables them to work well in areas with variable wind directions.

Here the generator and the gearbox can be placed near the ground thereby making maintenance easier. Some of p

There are a few particular types of VAWT machines:

• Darrieus wind turbines are shaped in the form of an eggbeater with two curved blades and have good efficiency. They create a large ripple torque and require an additional motor to run, as their starting torque is very low. Newer turbines are typically equipped with 3 or more blades for greater solidity of the rotor.
• The Giromill has straight blades and can self-startup easily. Its cycloturbine subtype has variable pitch which leads to high startup torque, good coefficient of performance, better resistance to turbulent winds and a lower blade speed ratio.
• Savonius wind turbines are drag type devices and are always self-starting; provided there are three scoops.

There are other unconventional designs also such as Ducted Rotor, Maglev wind turbine, Co-axial, multi rotor horizontal axis turbines and furling tail-twisted blade turbines.