Performance data for an axial-flow turbine with passive adaptive blades

Abstract

Passive adaptive blades for axial-flow marine current turbines offer the potential for blade load reductions without introducing failure modes inherent to active pitch mechanisms. To support the development of simulation tools for passive adaptive turbine rotors, an experimental data set from a laboratory-scale axial-flow turbine with passive adaptive blades is provided. The blades were fabricated with unidirectional off-axis carbon fiber, resulting in a coupling between flapwise deflection and spanwise twisting. The 0.45-meter diameter turbine was tested in an open-channel, recirculating flume at three flow speeds over tip-speed ratios 2-8. Blade and rotor loads were measured at 1 kHz using six-axis force/torque sensors at the root of a blade and on the drive shaft in the rotor hub, while deflection and twist at the blade tip were tracked using a high-speed camera. Frequency analysis of the blade loads revealed no evidence of flutter instability, with dominant frequencies identified only at the blade passing frequency and associated harmonics.