Recently, small hydropower attracts attention because of its clean, renewable and abundant energy resources to develop. However, suitable turbine type is not determined yet in the range of small hydropower and it is necessary to study for the effective turbine type. Moreover, relatively high manufacturing cost by the complex structure of the turbine is the highest barrier for developing the small hydropower turbine. Therefore, a cross-flow turbine is adopted because of its simple structure and high possibility of applying to small hydropower.
The result are summarized as follows 1) Air layer in the runner is very important factor to improve the turbine performance. Because of air layer , recirculation flow loss decreases from 14% to 1% in occasion of 1kW class hydro turbine.
2) In 80kW class hydro turbine, the region of Stage 1 produces almost 70% of output power from total output power.
3) Pressure and velocity at the runner blade around gives considerable effects on the performance of cross-flow hydraulic turbine simultaneously. Therefore, cross-flow turbine has the characteristics of both impulse turbine and reaction turbine.