This paper deals with the characteristics of wave energy conversion system combined with breakwater including an air-driven wells turbine and cross-flow water turbine. The wave energy converter with Oscillating Water Column(OWC) has mostly been studied to raise energy conversion efficiency. The aim of this research is to verify the effectiveness of curved seawater entrance section of OWC chamber through both numerical simulation using LabVIEW and scale model experiment in the 2-D wave tank.
Incident wave was assumed as sinusoidal, and other minor losses except for entrance loss were ignored, and also cavity resonance wasn't considered in the simulation. The simulation was conducted at 2.0sec in wave period and 0.13m in wave height. And 5 different entrance loss coefficients were used as parameters:0.01,0.02,0.1,0.5. The simulation result which contains the velocity of free-water surface, the vertical displacement of water and the available energy to the turbine shows that the effect of entrance loss coefficient is not significant under the assumptions as mentioned above.
Scale model with 4 different types of entrance section was used in the experiment. The model contains a cross-flow water turbine and a wells turbine. Experimental conditions were almost same as numerical simulation at 2.0sec in wave period, 0.13m in wave height, 0.7m in depth of water. Turbine RPM, output voltage from DC generator, water level in the OWC chamber and air pressure under the wells turbine were measured by CompactRIO system based on LabVIEW. The most obvious difference found in the experimental results depending on the geometry was a hydrodynamic performance from cross-flow water turbine: it was about 25%. Through the model experiment, it can be inferred that an elliptic curved surface whose horizontal distance is longer than vertical distance can improve wave energy conversion efficiency by reducing head loss in the fixed OWC chamber. The experimental results provide a blueprint for the inlet geometry design of wave energy conversion system combined with breakwater.