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Assessing the influence of inflow turbulence on noise and performance of a tidal turbine using large eddy simulations

Assessing the influence of inflow turbulence on noise and performance of a tidal turbine using large eddy simulations
Assessing the influence of inflow turbulence on noise and performance of a tidal turbine using large eddy simulations
Large eddy simulations of a model scale tidal turbine encountering inflow turbulence have been performed. This has allowed both unsteady blade loading and hydrodynamic noise radiation to be predicted. The study is motivated by the need to assess environmental impact of tidal devices, in terms of their acoustic impact on marine species.

Inflow turbulence was accounted for using a synthetic turbulence generator, with statistics chosen to represent the gross features of a typical tidal flow. The turbine is resolved in a fully unsteady manner using a sliding interface technique within the OpenFOAM® libraries. Acoustic radiation is estimated using a compact source approximation of the Ffowcs Williams–Hawkings equation.

It is observed that the long streamwise length scale of the inflow turbulence results in characteristic ‘humps’ in the turbine thrust and torque spectra. This effect is also evident in the far-field noise spectra. The acoustic sources on the blades are visualised in terms of sound pressure level and “Powell's source term”. These measures show that the dominant sources are concentrated at the blade leading edges towards the tip. This results from the high loading of the turbine blades, and causes the sound to radiate more akin to a monopole than a dipole.

The full scale source level, obtained from scaling of the simulation results, is found to be lower than comparable measured data reported in the literature; this is attributed to additional sources not included in the present study. Based on the predicted source level, no physical impact on fish is expected.
horizontal axis tidal turbine, large eddy simulation, inflow turbulence generator, acoustics, environmental impact
0960-1481
742-754
Lloyd, Thomas P.
bcc9ab5a-b791-4f5c-9272-64e7624dc720
Turnock, Stephen R.
d6442f5c-d9af-4fdb-8406-7c79a92b26ce
Humphrey, Victor F.
23c9bd0c-7870-428f-b0dd-5ff158d22590
Lloyd, Thomas P.
bcc9ab5a-b791-4f5c-9272-64e7624dc720
Turnock, Stephen R.
d6442f5c-d9af-4fdb-8406-7c79a92b26ce
Humphrey, Victor F.
23c9bd0c-7870-428f-b0dd-5ff158d22590

Lloyd, Thomas P., Turnock, Stephen R. and Humphrey, Victor F. (2014) Assessing the influence of inflow turbulence on noise and performance of a tidal turbine using large eddy simulations. Renewable Energy, 71, 742-754. (doi:10.1016/j.renene.2014.06.011).

Record type: Article

Abstract

Large eddy simulations of a model scale tidal turbine encountering inflow turbulence have been performed. This has allowed both unsteady blade loading and hydrodynamic noise radiation to be predicted. The study is motivated by the need to assess environmental impact of tidal devices, in terms of their acoustic impact on marine species.

Inflow turbulence was accounted for using a synthetic turbulence generator, with statistics chosen to represent the gross features of a typical tidal flow. The turbine is resolved in a fully unsteady manner using a sliding interface technique within the OpenFOAM® libraries. Acoustic radiation is estimated using a compact source approximation of the Ffowcs Williams–Hawkings equation.

It is observed that the long streamwise length scale of the inflow turbulence results in characteristic ‘humps’ in the turbine thrust and torque spectra. This effect is also evident in the far-field noise spectra. The acoustic sources on the blades are visualised in terms of sound pressure level and “Powell's source term”. These measures show that the dominant sources are concentrated at the blade leading edges towards the tip. This results from the high loading of the turbine blades, and causes the sound to radiate more akin to a monopole than a dipole.

The full scale source level, obtained from scaling of the simulation results, is found to be lower than comparable measured data reported in the literature; this is attributed to additional sources not included in the present study. Based on the predicted source level, no physical impact on fish is expected.

Full text not available from this repository.

More information

Accepted/In Press date: 7 June 2014
e-pub ahead of print date: 17 July 2014
Published date: November 2014
Keywords: horizontal axis tidal turbine, large eddy simulation, inflow turbulence generator, acoustics, environmental impact
Organisations: Faculty of Engineering and the Environment

Identifiers

Local EPrints ID: 375770
URI: http://eprints.soton.ac.uk/id/eprint/375770
ISSN: 0960-1481
PURE UUID: e5eda61d-5410-422b-86e2-1532bbc2f5c2
ORCID for Stephen R. Turnock: ORCID iD orcid.org/0000-0001-6288-0400
ORCID for Victor F. Humphrey: ORCID iD orcid.org/0000-0002-3580-5373

Catalogue record

Date deposited: 14 Apr 2015 08:51
Last modified: 10 Dec 2019 01:58

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