Scale reproduction of the flow field for tidal energy converters
Scale reproduction of the flow field for tidal energy converters
Marine current energy conversion technology is presently at the prototype stage where single devices are deployed, or planned for installation, at isolated testing sites. There is little detailed knowledge of the flow field properties at highly energetic tidal energy sites. Often peak flow speeds are measured but the nature of wave and bed-generate turbulence and the potential effects upon tidal energy devices are uncertain. This may lead to prototype devices being installed at sheltered or benign sites where the effects of waves are minimised and bed conditions induce low levels of turbulence. Another solution is for devices to avoid operation in these turbulent regions of flow but both solutions may result in reduced energy capture as rotor swept areas are constrained and potentially higher energy flows are not intercepted.
With little detailed knowledge of flow conditions at tidal energy sites it is difficult to model at smaller scale. However, there are methods of accurately reproducing scale seabed conditions and new lab-based high frequencies velocity measurements equipment can aid in the characterisation of the flow field. This work describes the modelling of sea bed roughness in the 21m tilting flume at the Chilworth hydraulics laboratory, University of Southampton. Mean flow velocity and higher order flow effects have been evaluated at locations upstream and downstream of porous mesh disks in order to quantify the effects of seabed roughness compared to smooth bed conditions upon both the general flow field and the downstream wake region.
Results show that the greater tractive forces close to the roughened bed induce a much more pronounced vertical velocity profile and increased turbulence in the lower region of the water column. However, this does not lead to increased wake mixing downstream of the rotor disk and indeed ensures that rotor disk proximity to the bed is a far more important issue than for smooth bed conditions.
Myers, L.E.
b0462700-3740-4f03-a336-dc5dd1969228
Bahaj, A.S.
a64074cc-2b6e-43df-adac-a8437e7f1b37
2008
Myers, L.E.
b0462700-3740-4f03-a336-dc5dd1969228
Bahaj, A.S.
a64074cc-2b6e-43df-adac-a8437e7f1b37
Myers, L.E. and Bahaj, A.S.
(2008)
Scale reproduction of the flow field for tidal energy converters.
10th World Renewable Energy Congress, Glasgow, July 2008, Glasgow, UK.
21 Jul 2008.
Record type:
Conference or Workshop Item
(Paper)
Abstract
Marine current energy conversion technology is presently at the prototype stage where single devices are deployed, or planned for installation, at isolated testing sites. There is little detailed knowledge of the flow field properties at highly energetic tidal energy sites. Often peak flow speeds are measured but the nature of wave and bed-generate turbulence and the potential effects upon tidal energy devices are uncertain. This may lead to prototype devices being installed at sheltered or benign sites where the effects of waves are minimised and bed conditions induce low levels of turbulence. Another solution is for devices to avoid operation in these turbulent regions of flow but both solutions may result in reduced energy capture as rotor swept areas are constrained and potentially higher energy flows are not intercepted.
With little detailed knowledge of flow conditions at tidal energy sites it is difficult to model at smaller scale. However, there are methods of accurately reproducing scale seabed conditions and new lab-based high frequencies velocity measurements equipment can aid in the characterisation of the flow field. This work describes the modelling of sea bed roughness in the 21m tilting flume at the Chilworth hydraulics laboratory, University of Southampton. Mean flow velocity and higher order flow effects have been evaluated at locations upstream and downstream of porous mesh disks in order to quantify the effects of seabed roughness compared to smooth bed conditions upon both the general flow field and the downstream wake region.
Results show that the greater tractive forces close to the roughened bed induce a much more pronounced vertical velocity profile and increased turbulence in the lower region of the water column. However, this does not lead to increased wake mixing downstream of the rotor disk and indeed ensures that rotor disk proximity to the bed is a far more important issue than for smooth bed conditions.
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Published date: 2008
Venue - Dates:
10th World Renewable Energy Congress, Glasgow, July 2008, Glasgow, UK, 2008-07-21 - 2008-07-21
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Local EPrints ID: 76069
URI: http://eprints.soton.ac.uk/id/eprint/76069
PURE UUID: 74567ddc-5678-44f1-aab9-0d0ae53ff3cf
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Date deposited: 18 Mar 2010
Last modified: 23 Jul 2022 01:49
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