Abstract: Energy capture device is the key component of the horizontal axis tidal current energy conversion system. Based on blade element momentum theory, a three bladed tidal current turbine is designed and tested. The blade geometry is determined by using the optimal blade design method for variable-speed operation. A hydrodynamic performance prediction model including necessary modifications is established, with which the turbine performance for various blade pitch angles is predicted. The prediction results suggest that the hydrodynamic design of the turbine is valid. Then the turbine is constructed and tested under real offshore conditions. Experimental results show that the turbine functions well and the power coefficient around the design point reaches 0.341, thus validating the effectiveness of the turbine design method. A comparison is made between experimental results and theoretical predictions. Although the experimental data is slightly lower, it is generally consistent with those derived from the model. Hence, the correctness and validity of the numerical prediction model are proven.

Key words: Blade element momentum theory, Energy capture device, Horizontal axis, Tidal current energy, Cyclone separator Filter Separation efficiency Numerical simulation