Abstract
Small hydropower generation is one of important alternative energy, and potential of small hydropower is great. Efficiency of small hydro turbines is lower than that of large one, and these small hydro turbine's common problems are out of operation by foreign materials. Then, there are demands for small hydro turbines to keep high performance and wide flow passage. Therefore, we adopted contra-rotating rotors which can be expected to achieve high performance and low-solidity rotors with wide flow passage in order to accomplish high performance and stable operation. Spokes needs to support rotors, and influence on the performance of the small hydro turbine. The performance of the contra-rotating small hydro turbine is investigated when the spokes shapes are changed. The test small hydro turbine is improved by the spoke shape modification, and the internal flow of it is clarified by the numerical analysis results
