Study on High Power Design of Contra-Rotating Small Hydroturbine with Centrifugal Force

Abstract

Contra-rotating rotors have high performance in internal flow conditions, so they are suitable as rotors for in-line small hydroturbines. However, a conventional contra-rotating rotor was composed of two axial flow rotors, so it had a specification suitable for high flow rate and low head. In order to achieve small hydroturbine suitable for low flow rate and high head, we propose a new type of contra-rotating rotors, which are composed of a hybrid rotor and a centrifugal rotor. We designed an in-line small hydroturbine using the new contra-rotating rotor and conducted power generation tests. Then, in order to achieve further improvements in power and head of the small hydroturbine, we investigated the performance and internal flow conditions of a small hydroturbine with shrouds installed on the contra-rotating rotors.