TY - JOUR T1 - On the spectral behaviour of the turbulence-driven power fluctuations of horizontal-axis turbines A1 - Deskos,Georgios A1 - Payne,Gregory S. A1 - Gaurier,Benoit A1 - Graham,Michael AD - Natl Renewable Energy Lab, Natl Wind Technol Ctr, Golden, CO 80401 USA. AD - Ecole Cent Nantes, Lab Rec Hydrodynam Energet & Environm Atmosper, 1 Rue Noe, F-44300 Nantes, France. AD - IFREMER, Marine Struct Lab, 150 Quai Gambetta,BP 699, F-62321 Boulogne, France. AD - Imperial Coll London, Dept Aeronaut, London SW7 2AZ, England. UR - https://doi.org/10.1017/jfm.2020.681 DO - 10.1017/jfm.2020.681 KW - flow-structure interactions N2 - In this article we consider the spectral behaviour of turbulence-driven power fluctuations for a single horizontal-axis turbine. To this end, a small-scale instrumented axial-flow hydrokinetic turbine model (diameter = 0.724 m) is deployed in the long water flume situated in the laboratory facilities of IFREMER in Boulogne-sur-Mer, France, and synchronous measurements of the upstream velocity and the rotor are collected for different tip-speed ratios. The study confirms previous findings suggesting that the power spectra follow the velocity spectra behaviour in the large scales region and a steeper power law slope behaviour (-11/3) over the inertial frequency sub-range. However, we show that both the amplitude of the power spectra and low-pass filtering effect over the inertial sub-range also depend on the rotor aero/hydrodynamics (e.g. dC(L)/d alpha) and the approaching flow deceleration and not solely on the rotational effects. In addition, we present a novel semi-analytical model to predict the dominant blade-passing frequency harmonics in the high-frequency regime using the rotationally sampled spectra technique. For all calculations, the distortion of incoming turbulence is taken into account. Y1 - 2020/12 PB - Cambridge Univ Press JF - Journal Of Fluid Mechanics SN - 0022-1120 VL - 904 IS - A13 ID - 76710 ER -