Proposal of Design Method for Large Tidal Current Turbine Incorporating Cavitation Occurrence

Among renewable energy sources, tidal current power generation systems, which are predictable over long time periods, are attracting attention. One way to achieve high power output from tidal current turbines is to increase the turbine diameter. However, the turbine diameter is limited by cavitation. In this study, a simple large turbine design method was proposed to obtain high power output while suppressing cavitation. The turbine design was based on blade element momentum (BEM) theory, which is widely used in tidal current turbines. A process for the modification of the angle of attack was incorporated into the design method based on BEM theory to suppress cavitation. The blade was NACA 63–415. Lift and drag characteristics of the blade and cavitation inception pressure were calculated numerically. The turbines were designed using a conventional design meth-od and the design method incorporating the angle of attack modification process. The power output of the turbine designed by the proposed method was increased by more than 50%. These results indicate that the proposed design method has the capability to design turbines with high output. In addition, the proposed design method is simple and applicable to a various blade. Therefore, the performance of tidal current turbines could be further improved by using more appropriate blade and the pro-posed design method.