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Optimum Wind-Energy Conversion Systems

1977; Annual Reviews; Volume: 9; Issue: 1 Linguagem: Inglês

10.1146/annurev.fl.09.010177.002151

1545-4479

Ulrich Hütter,

Fluid dynamics and aerodynamics studies

The history of energy-converting machines is the story of consistently increasing specific speed. This is also true for wind-energy converters jf we neglect the step backwards between 1868 and approximately 1910, when comparatively small low­ speed multiblade steel windmills were introduced, as a temporary help mainly for farming in semiarid areas. It was several centuries ago, during the first severe confrontation between Occident and Orient after the decline of the Roman Empire, that the European knights, aside from candied fruits and decimal figures, discerned the importance of those strange windmills, most probably with sail-wing rotors. At all events there does exist a document of 1105, six years after the end of the first crusade, which granted to the Benedictine monastery of Savigny a windmill privilegium ( Bilau 1933 and Golding 1955). From then on up to the end of the eighteenth century a consistently empirical development led finally to those well-known Dutch windmills with four-bladed rotors of from 18 up to 26 m diameter, optimum tangential tip-speed ratios 1.8 � Aw.RTR � 2.4, and maximum speed ratios when idling at zero output of up to 3.2 times the wind velocity VFFL in free flow. We define (1)