Experimental Investigation on the Performance of Savonius Rotors for Wave Energy Conversion

Oscillating water column (OWC) devices employing Savonius rotors were experimentally tested at varying wave conditions, rotor geometry, water depth and relative submergence depth. In addition to this, the rotor orientation, OWC orientation and blockage ratio were varied. Furthermore, a novel double OWC was tested. The results indicate that the best rotor configuration was d = 40 mm and α=30°. The performance of the rotor was better at a water depth of 280 mm at all the frequencies. Maximum rotational speed was recorded at relative submergence depth of 0.46. For the normal OWC the counter clockwise rotating rotor performed better at all the frequencies and the rpm increased with increasing frequency. On the other hand for the opposite OWC the clockwise rotating rotor performed better at all the frequencies and the rotor performance peaked at 0.8 Hz and 0.85 Hz. Increasing the blockage ratio did not improve the rotor performance. Finally, for the double OWC, the combined performance of the front OWC rotor and rear OWC rotor was the best at 0.8 Hz and 0.85 Hz.