Influence of Spoke Geometry on Performance and Internal Flow of Contra-Rotating Small-Sized Hydroturbine

Abstract

Small hydropower generation is one of important alternative energy, and potential of small hydropower is great. Efficiency of small hydroturbines is lower than that of large one, therefore there are demands for small hydroturbines to keep high performance. Then, we adopt contra-rotating rotors, which can be expected to achieve high performance. Efficiency of the contra-rotating small hydroturbine is high in pico-hydroturbine and high efficiency can be kept in wide flow rate range. On the other hand, the relatively large loss occurs at the spokes which should be installed for this small hydroturbine to support the rotors. Then, the new spoke to increase its performance is proposed in this research. In the present paper, the performance of the contra-rotating small hydroturbine using different spoke geometry is shown by the numerical results. Further, internal flow condition between the front and rear rotors are investigated.