Tidal current is a promising renewable energy source. Previous studies have investigated the influence of surface waves on tidal turbines in many aspects. However, the turbine wake development in a surface wave environment, which is crucial for power extraction in a turbine array, remains elusive. In this study, we focus on the wake evolution behind a single turbine and its interaction with surface waves. A numerical solver is developed to study the effects of surface waves on an industrial-size turbine. A case without surface wave and two cases with waves and different rotor depths are investigated. We obtain three-dimensional flow field descriptions near the free surface, around the rotor, and in the near- A nd far-wake. In a comparative analysis, the time-averaged and instantaneous flow fields are examined for various flow characteristics, including momentum restoration, power output, free surface elevation and vorticity dynamics. A model reduction technique is employed to identify the coherent flow structures and investigate the spatial and temporal characteristics of the wave-wake interactions. The results indicate the effect of surface waves in augmenting wake restoration and reveal the interactions between the surface waves and the wake structure, through a series of dynamic processes and the Kelvin-Helmholtz instability.
|Original language||English (US)|
|Journal||Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences|
|State||Published - Feb 3 2021|
Bibliographical noteFunding Information:
Data accessibility. A video file (animation.mp4) is uploaded with the revised manuscript as electronic supplementary material data to the readers. Authors’ contributions. Z.L. carried out the study conceiving, solver coding, data processing, manuscript drafting and revising, and Latex editing. K.G. initiated the project and provided academic guidance in the early stage of this research and helped prepare drafts of the paper. Y.L. coordinated the study, advised and helped to revise the manuscript. Z.F. participated in drawing some of the schematic figures and contributed to writing the paper. L.S. advised in the study and helped to revise the manuscript. All authors gave final approval for publication and agree to be held accountable for the work performed therein. Competing interests. We declare we have no competing interests. Funding. Y.L. and Z.F. are supported by National Natural Science Foundation of China (grant nos 51761135012 and 11872248) and Ministry of Science and Technology of China (grant no. 2017YFE0132000).
© 2021 The Author(s).
- coherent structure
- free surface
- reduced order modelling
- tidal turbine
- wake flow