An experimental study of surface wave effects on two interacting tidal turbines

The development of tidal turbine farms desires an understanding of the effects of free-surface waves and turbine interactions. The objective of this paper is to investigate surface wave effects on the performance of two tidal turbines axially aligned with current flows. Scale model experiments with and without regular waves are conducted on two horizontal-axis tidal turbines in a towing tank. Regular waves have no effect on time-averaged performance but induce periodic fluctuations in rotor torque for the upstream turbine that is not impacted by the wake of other turbines. Waves improve downstream turbine performance marginally, and the amplitude of torque fluctuations is frequently lower than that of the upstream turbine. A comparison of five wave situations with varying wave heights and periods is also explored. It is demonstrated that as the wave height and period increased, so did the range of torque variation.