Abstract
The spiral water turbine (screw-type turbine, spiral water mill) has a runner whose shape is same as that of Archimedes pump. As this turbine can run on the very low head situation, and it can be very easily set to open water channels, it is suitable to for the very small hydraulic power generating. In this study, the internal flow and its relation to the generated power is analyzed both by model experiment and by CFD. When the whole turbine sinks, the power can be estimated by angular momentum formula. On the other hand, when only a part of the turbine sinks, the internal flow changes largely, and the turbine works as the displacement type of turbine. In both cases, the axial flow velocity is almost same as the axial moving speed of the spiral blade.
