New answers tagged renewable-energy
First, it's not only drag that slows down the air, every force has to be matched by an equal and opposite force including lift. Second, friction is not the sole cause of drag, indeed there's drag on an airfoil in an inviscid fluid due to pressure. So why we need sophisticated airfoil design when traditional windmills can work and how modern wind turbines ...
The answer to this question is very much analogous to the answer to how aeroplanes fly. See Physics SE Question "What Really Allows Airplanes to Fly?" and the best (IMO) answer is this one here. But basically the airfoils, sails or vanes - whatever they may be called - deflect the flow of air. They do this by pushing on the air and changing the latter's ...
Generally a windmill rotates in the clockwise direction. If it rotates anti-clockwise, it will consume energy, so that it does not produce power.
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