Study on the Unsteady Characteristics of Impulse Turbine for OWC Wave Energy Converter under Sinusoidal Flow

Impulse turbine is widely used device as an energy converter in OWC type wave plant especially in Korea because of the wide operating range. Because the driven torque of blade is extracted form wave energy which is not an infinity force like fossil energy source, study on the unsteady characteristics of turbine such as self-starting performance are important to predict the performance of pilot plant in real sea conditions. The transient calculation method for performance prediction of OWC impulse turbine is proposed in the present paper using commercial CFD code Fluent, which is supposed to provide more valuable unsteady information during self-starting and rotating of the turbine. The rotation of turbine is derived from the angular acceleration, which are obtained from torques integration on rotor blades. The frictions and electricity generator loading are regarded as the counteractive force contributing to the above torque calculations. The experimental study is carried out using wave simulator test rig which can simulate a sinusoidal flow in test section. The RPM of turbine, torque of blade and pressure different induced by turbine are measured to study unsteady characteristics under variable flow and resistance loading conditions.