Vertical Axis Wind Turbine Or VAWT

Wind energy has been used in different forms by us for centuries today. However in this modern age it has emerged as an alternative source of energy for the ever expanding demand for electricity. It can now be even used to produce electricity for households. For this purpose, a Vertical Axis Wind Turbine or VAWT is needed.

Vertical Axis Wind Turbine is a wind power machine. It is designed in such a way that it can be installed on a flat roof. It can even be made to stand on a platform in both a rural or urban environment. The VAWT are an economical alternative for the small scale user. Earlier models had problems like their inability to self-start in light winds as well as the production of noise and vibration levels. These problems have been solved now.

There are various subtypes of a Vertical Axis Wind Turbine. They are Darrieus wind turbine, Gorlov helical turbine, Giromill and Savonius wind turbine.

The Darrieus wind turbine is also known as an 'Eggbeater' turbine. It is known to be efficient however it produces large torque ripple and cyclic stress on the tower. This makes it less reliable. Also, it generally requires an external power source. It also requires an additional Savonius rotor to start turning, because of a low starting torque.

Gorlov helical turbine is an advanced form of the Derrieus model. It is able to self start and has a lower torque ripple. Also the noise and vibration level is a way lower. Also the cyclic stress is very low. The tested or mature designs of this turbine are known to be much reliable.

The Giromill turbine is a subtype of Darrieus turbine. The only difference is that it has straight blades, instead of the curved ones. This type of turbine has a variable pitch that can reduce the torque pulsation. This facilitates a high starting torque; a wide, relatively flat torque curve; a lower blade speed ratio.

Also the coefficient of performance is a way lower. This helps it to operate more efficiently in turbulent winds. The turbine also has a lower blade speed ratio which reduces the blade bending stresses. Also the turbine is self-starting.

Savonius wind turbine is a drag-type device. It has two or more scoops, which are used in anemometers, the Flettner vents and in some highly-reliable low-efficiency power turbines. These turbines are usually self-starting in case there are just three scoops.

A Vertical Axis Wind Turbine is very safe to be used in public spaces, parks, wildlife parks and on buildings or any other populated places. They could provide the users with a low cost and efficient alternative source of energy.