Optimization of the Rear Propeller Profile of a Counter-Rotating Type Tidal Stream Power Unit Based on CFD Simulation

In order to convert the kinetic energy of tidal stream, the authors have invented a novel counter-rotating type tidal-stream power unit, which is composed of the tandem propellers and the double rotational armature type peculiar generator without the traditional stator. The commercial code (GH-Tidal Bladed) and academic in-house code (SERG-Tidal) based on blade element momentum theory have been proven well applied to performance prediction for the traditional wind turbine and tidal turbine. However, for the counter-rotating type tidal turbine, it is very difficult to simulate the mutual effect between the tandem propellers using blade element momentum. This paper sets up a CFD model for the counter-rotating type tidal turbine and optimizes the chord and pitch distribution of the rear propeller. The predicted results are compared between the original turbine and optimized turbine, which show great improvement in power efficient after optimization.