A large scale model experimental study of a tidal turbine in uniform steady flow

• A new large scale tidal turbine test facility was designed and constructed.
• An experimental study of a large scale turbine in steady uniform flow is presented.
• Both model performance and wake characteristics are presented.
• Varying the inflow speed yielded little difference in the wake velocity deficit.

An experimental study measuring the performance and wake characteristics of a 1:10th scale horizontal axis turbine in steady uniform flow conditions is presented in this paper.Large scale towing tests conducted in a lake were devised to model the performance of the tidal turbine and measure the wake produced. As a simplification of the marine environment, towing the turbine in a lake provides approximately steady, uniform inflow conditions. A 16 m long×6 m wide catamaran was constructed for the test programme. This doubled as a towing rig and flow measurement platform, providing a fixed frame of reference for measurements in the wake of a horizontal axis tidal turbine. Velocity mapping was conducted using Acoustic Doppler Velocimeters.The results indicate varying the inflow speed yielded little difference in the efficiency of the turbine or the wake velocity deficit characteristics provided the same tip speed ratio is used. Increasing the inflow velocity from 0.9 m/s to 1.2 m/s influenced the turbulent wake characteristics more markedly. The results also demonstrate that the flow field in the wake of a horizontal axis tidal turbine is strongly affected by the turbine support structure.