éolienne lente

CONT: A partir de 1870, l'éolienne lente à pales multiples fait son apparition en Amérique puis en Europe. Les pales dont le nombre varie de 12 à 24 couvrent toute la surface de la roue ou la presque totalité.

CONT: Windmills therefore fall into different classes according to the value of tip speed ratio (TSR) at which they operate. Slow running windmills, like the common farm air turbine, may operate at TSR = 1 or 2, and with the fastest running windmills, perhaps up to TSR = 6 or 7. (...) In the case of horizontal shaft windmills, it [the fast running windmill] resembles an ordinary propeller with rather wide blades, whereas a slow running windmill must be fitted with a large number of blades.