Wednesday, 10 October 2012

What exactly is vertical-axis wind turbine

By Diane Levey


History

The vertical axis wind turbines (VAWTs) happen to be in use for a lot more than 1300 years. It was traditionally made use of to pump water and grind grains. It can be one of the varieties of wind turbine, the other becoming the horizontal axis wind turbines (HAWTs). These VAWTs are cost-effective, reputable and sensible approach of power generation.

Why is it called as Vertical Axis Wind Turbine?

This name was given to it, as it has a vertically set main rotor shaft. The base of the wind turbine is where the main components are present. In this turbine, the gearboxes and generators can be located close to the ground making it easier to repair and do service to these components. These turbines need not be pointed towards the wind.

Main advantages of vertical axis wind turbines

Omni-directional - This turbine can create energy even when it is not positioned towards the wind's direction. They also have very much less moving parts producing it cost-effective and more trustworthy.

Significant amount of torque production - This can be potential because of the greater surface area with the blades.

Slow speed spinning - Spinning at lower speed offers the advantage of the turbines to function efficiently even in higher wind speed, which reduces the vibrations and noise making it safer for birds.

Other Positive aspects

More variety of turbines can be set up in any offered space of wind farms as they can be crammed closer together when in comparison with the horizontal axis wind turbines that need a lot more spacing (ten instances their width).

Wind farms set up with VAWTs can produce power output ten times over the horizontal axis wind turbines utilized in the wind farm from the same size.

Disadvantages of vertical axis wind turbines

The VAWTs have low dynamic stability and starting torque problems and also will easily stop when the wind blows very hard

These turbines are very sensitive to conditions related to off-design. They can be operated only in environments with lower wind speed, as they have to be installed at lower heights.

The central axis is exactly where the blade spins about and hence can effortlessly develop into weak, which causes the blades to crack, flex and break major to terrible failure. Thanks to this drawback, this turbine is regarded as much less reliable than the HAWTs (Horizontal axis wind turbines).

Other disadvantage

In the course of the early period the design of this turbine had the pulsatory torque, which was produced in the course of the blade's big bending moments and each revolution, but this was considered a major drawback. Later this dilemma was solved by using a new style that had the helical twist of blades.

Vertical axis wind turbine - Varieties

Lift-based VAWT - Operates at higher tipspeed ratios for example, Cycloturbines and Darrieus rotors

Drag-type VAWT - Operates at a somewhat lower tipspeed ratios for instance, Savonius rotors

Recently a different type of VAWT has been developed. This is a unique mix of both the Savonius and Darrieus VAWTs. This has been developed in order to improve the performance at a lower r.p.m and lower wind speed. Silent turbine is the output of higher wind speeds and is suitable for residential purposes.




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