1-MW class tidal stream turbine is proposed and the performance is studied numerically by the both of blade element theory (BEMT) and computational fluid dynamics (CFD). The power coefficient according to the TSR(Tip Speed Ratio) is mainly focused for the evaluation of the performance of turbine. The computed results of the both methods are compared and analyzed in the present study. Additionally the cavitation inception is also treated and quantified by the minimum allowable immersion depth for cavitation free according to the variation of TSR. The comparison with experimental data is expected to be carried out in near future.
According to the increase of the consumption of the carbon-based energy, the global warming becomes a hot issue nowadays. Among many reusable energy resources wind and tidal stream energies are conceptually simple to adopt and the kinetic energy of the stream can be easily absorbed for the rotation of the electric power generators. The tidal current has its own superb advantages over the wind, such as the higher energy density and the consistent energy supply while there is somewhat difficult installation in harsh environmental condition. Tidal current power plant can be categorized mainly into two types according to the direction of its turbine axis relative to the incoming flow. One is the horizontal axis type (HAT) which is basically a reverse concept of the marine propellers and the other is the vertical axis type (VAT) which has vertical foils rotating around the shaft normal to the current stream which is similar to the configuration of Voith-Schneider propeller. While the VATs' main advantage is its directional independency to the incoming flow, the HATs are conceptually simple and known to have higher efficiency with a better cut-in characteristic (Fergal, et al., 2010).