On utilizing the orbital motion in water waves to drive a Savonius rotor

In wave motion, the water particles are known to follow orbital paths. This orbital motion was studied and a five bladed Savonius rotor was built to extract energy from the orbiting particles. Experiments were performed on a rotor placed parallel to the incoming waves in a two-dimensional wave channel by varying the frequency of the wave generator, which produced sinusoidal waves. The rotor submergence below the mean level was varied. The flow around the rotor was studied with particle image velocimetry (PIV) measurements. It was found that the rpm of the rotor (Nn) increases with an increase in wave frequency. An increase in wave height also increases the Nn values, as the kinetic energy of the particles' orbital motion increases. The optimum Nn values are obtained when the rotor is placed close to the water surface at the minimum submergence of 1.06d where ‘d’ is the rotor diameter.