On the spectral behaviour of the turbulence-driven power fluctuations of horizontal-axis turbines

Type Article
Date 2020-12
Language English
Author(s) Deskos Georgios1, Payne Gregory S.2, Gaurier BenoitORCID3, Graham Michael4
Affiliation(s) 1 : Natl Renewable Energy Lab, Natl Wind Technol Ctr, Golden, CO 80401 USA.
2 : Ecole Cent Nantes, Lab Rec Hydrodynam Energet & Environm Atmosper, 1 Rue Noe, F-44300 Nantes, France.
3 : IFREMER, Marine Struct Lab, 150 Quai Gambetta,BP 699, F-62321 Boulogne, France.
4 : Imperial Coll London, Dept Aeronaut, London SW7 2AZ, England.
Source Journal Of Fluid Mechanics (0022-1120) (Cambridge Univ Press), 2020-12 , Vol. 904 , N. A13 , P. 27p.
DOI 10.1017/jfm.2020.681
WOS© Times Cited 18
Keyword(s) flow-structure interactions

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.

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