Measurement of Service Strains of the Blade of "Wind-Lens"(Mechanical Systems)

Abstract

Measurement of service strains of the blade of Wind-lens turbine was conducted by using wireless strain measurement system in a wind tunnel apparatus. Wind-lens turbine has demonsrated power augmentation by a factor about 2-5 compared with a bare wind turbine, for a given turbine diameter and wind speed. Mean strain and vibrational strain variation range at the root of the blade was increased with the increase of uniform flow velocity of the wind tunnel. The phenomenon of vibration of the blades of Wind-lens turbine was due to a flutter or flow-induced vibration, self-excited oscillation induced by vortices around the blades, in a certain range of flow velocity. The increase of strain variation range at the root of the blades in the case of intense variation of wind direction was caused by a gyro-moment due to a yawing movement of the Wind-lens turbine. The intense variation of wind velocity, in addition to that of wind direction, caused extreme large vibration amplitude, or strain variation.