Performance of vertical-axis type straight-bladed Darrieus turbine with elastic blades (Performance improvement by deformation of blades)

Abstract

The characteristics of a straight-bladed Darrieus turbine (Gyro-mill turbine) with elastic blades are experimentally studied. The same structured turbine with rigid blades is also studied for comparison. The turbine with elastic blads is shown to have the following characteristics. When the T.S.R. (tip speed ratio) is small, less than 1, it generates very large torque like a drag-type turbine, and it can start by itself. On the other hand, when the T.S.R. is large, it shows the ordinary characteristics of the lift-type turbine, but the T.S.R. is limited less than 2. The deformation of the turbine blades is observed by a high-speed video movie, and it is shown that the torque rises not because of the wind drag but of the lift due to the deformation when the T.S.R. is small.The starting torque is also increased. Operation under too high rotation speed, which is sometimes dangerous, is also avoided by the deformation due to the centrifugal force which becomes significant when the rotation speed is high.

Keywords

• darrieus turbine
• elastic blade
• efficiency
• wind tunnel test
• renewable energy
• fluid dynamics