Research on hydrodynamic characteristics of a floating horizontal axis tidal turbine considering wave and platform motion

The floating horizontal-axis tidal turbine (FHATT) stands out as the most commercially viable tidal energy device. This paper reviews recent literature on FHATT and summarizes experimental and computational fluid dynamics (CFD) methods employed in FHATT research. Based on this foundation, the coupling effects of wave and platform motion (pitch/roll) on FHATT hydrodynamic performance were investigated through flume experiments and CFD simulations. The variations of the power coefficient (C_P) and thrust coefficient (C_T) are analyzed under different platform motion periods, amplitudes, wave periods, and wave heights. The results demonstrate that under the coupling of waves and pitch motion, C_P, C_T exhibit dual-frequency oscillations based on the pitch period, with oscillation amplitudes increasing with both pitch frequency (wave frequency) and pitch amplitude (wave height). Within the working conditions of this study, the maximum mean output power under the coupling of pitch motion and waves increases by 26.1%. The maximum fluctuation amplitude of C_P reaches 349.8%. When waves and roll motion are coupled, wave parameters dominate, while the influence of roll motion can be ignored. Moreover, the hydrodynamic fluctuations induced by waves and platform motion can couple with each other. This coupling effect not only amplifies the fluctuation amplitude of hydrodynamic coefficients but also has the potential to offset each other. These findings provide insights into the structural design and system control of FHATT, serving as valuable references for FHATT development.