TURBINE

摘要

A turbine for extracting energy from a moving fluid (B) such as wind or a river comprises a rotatable frame on which are mounted openable and closeable flaps. The flaps are hinged to the frame so that they open to present minimal frontal area to the fluid as they move upstream and close to present maximum frontal area to fluid moving downstream, thus causing the frame to rotate. In order to minimise shocks as the flaps close, the tip (E) of each flap directed towards the frame rotational axis as the flap moves with the fluid flow has a concave curvature on its downstream face in a cross section normal to the frame rotational axis. The remainder (D) of the flap away from the tip preferably has a concave curvature on its upstream face.