windmill (redirected from flings cap over the windmills)

windmill, apparatus that harnesses wind power for a variety of uses, e.g., pumping water, grinding corn, driving small sawmills, and driving electrical generators. Windmills were probably not known in Europe before the 12th cent., but thereafter they became familiar landmarks in Holland, England, France, and Germany. The typical Dutch windmill, also called the tower type, has a huge tower of stone, brick, or wood, in contrast to the German, or post, mill, the distinctive feature of which is that the whole building revolves on a central post. At the top of either type there is a revolving apparatus to which four to six arms are attached. The arms, usually 20 to 40 ft (6–12 m) long, bear sails constructed of light wood, or of canvas attached to a frame. A small fan serves as a rudder to keep the wheel facing the wind.

More modern American windmills have high towers of light steel girders; at the top is a wheel with many sheet-metal concave and "warped" vanes (sails) about 4 ft (1.2 m) long. The wheel is kept automatically facing the wind by a broad tail geared to a shaft. They have been widely used for pumping water in rural parts of the United States. Such windmills can also be used to generate about one kilowatt of elecricity.

Larger windmills, such as the modern propellerlike wind turbines, can have rotors (the blade assembly) that span 200 ft (60 m) or more. These wind turbines, often joined together in wind farms, can produce 1.5 MW or more of electricity and can serve as a significant source of electric energy in plains and coastal areas (including offshore locations). Wind turbines have been most extensively used in Europe, where Denmark, for example, is undertaking to generate 50% of its electricty using wind power by 2030. As many as 2,000 small wind turbines are used in Inner Mongolia to provide local electric power to nomadic people.

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windmill

Machine for harnessing the energy of the wind using sails mounted on a rotating shaft. The sails are mounted at an angle or are given a slight twist, so that the force of wind against them has two components, one of which, in the plane of the sails, causes rotation. Like waterwheels, windmills were among the original prime movers that replaced human beings as a source of power. Their most important traditional use was for grinding grain, though in certain areas their use in land drainage and water pumping was equally important. Windmill use became increasingly widespread in Europe (particularly the Netherlands) from the 12th century to the early 19th century, but thereafter slowly declined. Interest in windmills for generating electric power revived in the 1970s. See also wind power.

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windmill

1. a machine for grinding or pumping driven by a set of adjustable vanes or sails that are caused to turn by the force of the wind

2. the set of vanes or sails that drives such a mill

3. Brit a toy consisting of plastic or paper vanes attached to a stick in such a manner that they revolve like the sails of a windmill

4. a small air-driven propeller fitted to a light aircraft to drive auxiliary equipment

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windmill [′win‚mil]

(mechanical engineering)

Any of various mechanisms, such as a mill, pump, or electric generator, operated by the force of wind against vanes or sails radiating about a horizontal shaft.

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windmill

A large machine in which the wind acts on a number of vanes or blades, rotating them about an axis, thereby producing mechanical power; once widely used for grinding grain, sawing timber, and pumping water. The earliest windmills in America (similar to those in the Netherlands) had four very large, slowly moving blades that were cloth-covered, and required the constant attendance of an operator. In 1854, a patent was issued for an entirely new type of windmill, having a large number of small blades, which was self-regulating and could operate without human intervention; this feature greatly increased its practical application, especially for pumping water. In the latter part of the 20th century, large two-bladed windmills have been assembled in large groups called “farms” for the environment-friendly generation of electrical power.