Development of Micro Hydraulic Turbine Applicable to Mountain Torrents and Rivers to Coexist with Natural Ecosystem

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We are under obligation to coexist with natural ecosystem and to cope with warming global environment, for the next leap in hydroelectric power exploitations. In such circumstances, this research proposes a new type hydraulic turbine, named "Gyro-Type Hydraulic Turbine". The rotor is composed of some blades with high aspect ratio and the turbine is suitable for shallow stream with high velocity in mountain torrents and/or rivers. Then, the turbine scarcely disrupts the natural stream and environment, because the rotating plane of the submerged rotor is nearly parallel to the stream without casings and/or penstocks. Moreover, it is not necessary to start the public works on a large scale because the generator connected with the rotor shaft can be easily set on the simple stand over the water level.The rotor of diameter 500 mm, which is composed of three blades with NACA0018 hydrofoil, was prepared to the experiments, and the main knowledge about the turbine characteristics are as follows.(1)The turbine characteristics do not satisfy the similarity laws against the stream velocity, in this investigation.(2)The attack angle to the blade changes in the rotation because the rotating plane is moderately inclined. The output can be bettered with 20% as compared with the two dimensional blade, when the blade is twisted so as to get the best lift-drag ratio.(3)The head between upstream and downstream of the rotor is affected by not only the rotational speed, namely the output, but also the blade profile.(4)The flow pattern and the pressure around the rotating blade can be predicted well with CFD, for instance, the large circulation occurs over the blade suction surface with the large attack angle, owing to the flow separation at the leading and the trailing edges.