Study on High Pressure Design of Contra-Rotating Small Hydroturbine

Abstract

It is requested that the hydroturbine be a small size and have high performance. Therefore, we adopted contra-rotating rotors, which can be expected to achieve radial compactification and high performance. However, when the rotors become smaller, the output power of conventional contra-rotating rotors, which are composed of axial flow rotors, is low. In order to achieve small size, high performance and high output power simultaneously, we propose a new type of contra-rotating rotors, which are composed of a hybrid rotor and a centrifugal rotor. In the present paper, we focus on deflection angle of the hydroturbine composed of these rotors as a first step of this research, and investigate performance by the numerical analysis. As a result, we clarified that there is a possibility that even a negative deflection angle functions as a hydroturbine unlike the conventional contra-rotating rotors and leads to best performance.