To cope with the warming global environment, the hydropower should occupy the attention of the electric power generation system as clean and cool energy sources. In such a situation, the tidal current has scarcely been utilized for the power generation. The authors have proposed and developed a new type of generator with counter-rotating rotors instead of the usual mechanism. This paper discusses the effects of the blade profiles on the hydraulic performances. As a result, the design materials for the solidity of the axial flow runners suitable for the given water circumstances are induced from above discussions.
To cope with the warming global environment, the hydropower should occupy the attention of the electric power generation system as clean and cool energy sources. In such a situation, the tidal current has scarcely been utilized for the power generation, for instance, the Kanmon Straits in Japan has about 54 MW hydraulic energy. It may be appropriate to apply the high specific speed hydraulic turbine for the tidal power generation. It is also desirable to make the machine compact size and simple composition, but the usual generator may reject such desires. That is, it is necessary, for getting sufficiently the electric power, to make the rotor diameter large or equip with the accelerator such as a gear-box, because the electric power is in proportion to the rotational speed in the magnetic field. Therefore, the authors have proposed and developed a new type of generator with counter-rotating rotors instead of the usual mechanism, which can make the generator diameter small on account of relatively double the rotational speed. Moreover, it is extremely easy to board on the floating buoy moored already in the strait, because the inertia moment of the rotor rotation is counter-balanced successfully (Kanemoto and Tanaka, 2001; Tanaka and Kanemoto, 2004; Kanemoto and Osono, 2004).
