Vertical Axis Air Turbine in Oscillating Water Column Systems.

The present paper deals with a study of an air turbine as power take-off in Oscillating Water Column systems. In Particular, the focus of the study is on the analysis of the air turbine performance in ducted configuration. Savonius type turbines were tested as a function of air flux oscillation frequency. In more details, a turbine with an overlap ratio of 1/6 was used, while three air flux oscillating frequencies are imposed: 0.1, 0.5, 1 and 1.5 Hz. In order to measure turbine performance, a specific experimental setup was built, based on an OWC simulator. The testing tube (operating as power take-off simulator) was built using transparent materials to allow Particle Image Velocimetry measurement. A simple band brake system was used to apply load to turbine shaft and to measure turbine torque. Therefore, turbine torque, rotational speed, pressure drop and input air velocity were registered and turbine power and power coefficient as a function of tip speed ratio were calculated. [ABSTRACT FROM AUTHOR]