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Giromill Darrieus Wind Turbines
What is a Giromill wind turbine - Darrieus (VAWT)
A Giromill is a Darrieus (1) type vertical axis wind turbine (2) (VAWT) generator. Unlike the more common Savonius (3) VAWT, the Giromill wind turbine uses lift forces generated by vertical aerofoils to convert wind energy into rotational mechanical energy.
The giromill was included in Darrieus's 1927 patent for vertical aerofoil powered vertical axis wind turbines, however development is now starting again on new giromills which take advantage of modern ultra strong light materials to produce turbine blades robust enough to cope with the stresses they are put under.
The giromill is typically powered by two or three vertical aerofoils attached to the central mast by horizontal supports. While it is cheaper and easier to build than a standard Darrieus turbine, it is less efficient, also requires strong winds (or a motor) to start, and can sometimes struggle to maintain a steady rate of rotation. However, they work well in turbulent wind conditions and are an affordable option where a standard horizontal axis windmill type turbine is unsuitable.
Buy a Giromill Wind Turbine
This Italian made 500 Watt 24 Volt giromill (4) is available for sale through eBay for around £800.
The Cycloturbine
A variant of the Giromill is the Cycloturbine (pictured above) which uses a vane to mechanically orient the pitch of the blades for maximum efficiency. This gives the cycloturbine the advantage over other Darrieus wind turbines of self-starting. In low winds the blades are pitched flat against the wind generating drag forces and starting the turbine turning. As the rotational speed increases the blades are pitched so that the wind flows across the aerofoils generating lift forces and accelerating the turbine.
Web Link References
(1) http://www.reuk.co.uk/Darrieus-Wind-Turbines.htm(2) http://www.reuk.co.uk/VAWT-Vertical-Axis-Wind-Turbine.htm
(3) http://www.reuk.co.uk/Savonius-Wind-Turbines.htm
(4) http://www.reuk.co.uk/Buy-a-VAWT-Vertical-Wind-Turbine.htm
Article from REUK.co.uk:
http://www.reuk.co.uk/Giromill-Darrieus-Wind-Turbines.htm
Published: 30th January 2007
© REUK 2009