Experimental investigation into downstream field of a horizontal axis tidal stream turbine supported by a mono pile

Abstract A deep insight into wake of a tidal stream turbine can be essential to make tidal stream energy commercially viable. This study is to experimentally investigate downstream field of a horizontal axis tidal stream turbine supported by a mono pile. Two scenarios with and without a rotor are considered and compared with each other in this study. An advanced Acoustic Doppler Velocimeteris employed to measure the time-varying velocities up to eight rotor diameter downstream. Analyses of results show that the flow field within three rotor diameter downstream is strongly influenced by the supporting structures, which lead to asymmetric recovery trend for velocity, turbulence and Reynolds shear stress. Besides, flow characteristics within various lateral distances away from the rotating axis tend to recover in different rates. Both the rotor rotation and supporting structures result in highly anisotropic turbulence in the downstream field. Bed shear stress in the downstream field nearly doubles due to the rotating rotor, although its distribution pattern does not change.