FIELD: windmills for driving electric generators, propellers of water transport, etc. SUBSTANCE: air stream used by windmill is shaped by force in wind tunnel so that speed of air stream running on propeller in narrow section of tunnel increases many times compared to its speed at inlet of wind tunnel. For obtaining maximal possible power from air stream, inlet and outlet sectional areas of wind tunnel should be equal and definite geometric relation should be maintained between diameters of air and water propellers. EFFECT: improved power taken off air stream. 10 cl, 2 dwg
