Performance and wake characteristics of tidal turbines in an infinitely large array
The efficiency of tidal-stream turbines in a large array depends on the balance between negative effects of turbine-wake interactions and positive effects of bypass-flow acceleration due to local blockage, both of which are functions of the layout of turbines. In this study we investigate the hydrod...
| Main Authors: | , |
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| Formato: | Journal article |
| Idioma: | English |
| Publicado: |
Cambridge University Press
2021
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| _version_ | 1826258369297514496 |
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| author | Ouro, P Nishino, T |
| author_facet | Ouro, P Nishino, T |
| author_sort | Ouro, P |
| collection | OXFORD |
| description | The efficiency of tidal-stream turbines in a large array depends on the balance between
negative effects of turbine-wake interactions and positive effects of bypass-flow acceleration due to local blockage, both of which are functions of the layout of turbines. In
this study we investigate the hydrodynamics of turbines in an infinitely large array with
aligned or staggered layouts for a range of streamwise and lateral turbine spacing. First,
we present a theoretical analysis based on an extension of the Linear Momentum Actuator
Disc Theory (LMADT) for perfectly aligned and staggered layouts, employing a hybrid
inviscid-viscous approach to account for the local blockage effect within each row of
turbines and the viscous (turbulent) wake mixing behind each row in a coupled manner.
We then perform Large-Eddy Simulation (LES) of open-channel flow for 28 layouts of
tidal turbines using an Actuator-Line Method (ALM) with doubly periodic boundary
conditions. Both theoretical and LES results show that the efficiency of turbines (or the
power of turbines for a given bulk velocity) in an aligned array decreases as we reduce
the streamwise turbine spacing, whereas that in a staggered array remains high and may
even increase due to the positive local blockage effect (causing the local flow velocity
upstream of each turbine to exceed the bulk velocity) if the lateral turbine spacing is
sufficiently small. The LES results further reveal that the amplitude of wake meandering
tends to decrease as we reduce the lateral turbine spacing, which leads to a lower wake
recovery rate in the near-wake region. These results will help to understand and improve
the efficiency of tidal turbines in future large arrays, even though the performance of real
tidal arrays may depend not only on turbine-to-turbine interactions within the array but
also on macro-scale interactions between the array and natural tidal currents, the latter
of which are outside the scope of this study. |
| first_indexed | 2024-03-06T18:32:55Z |
| format | Journal article |
| id | oxford-uuid:0a410cbf-8fa3-4661-882c-35361066495b |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T18:32:55Z |
| publishDate | 2021 |
| publisher | Cambridge University Press |
| record_format | dspace |
| spelling | oxford-uuid:0a410cbf-8fa3-4661-882c-35361066495b2022-03-26T09:22:52ZPerformance and wake characteristics of tidal turbines in an infinitely large arrayJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:0a410cbf-8fa3-4661-882c-35361066495bEnglishSymplectic ElementsCambridge University Press2021Ouro, PNishino, TThe efficiency of tidal-stream turbines in a large array depends on the balance between negative effects of turbine-wake interactions and positive effects of bypass-flow acceleration due to local blockage, both of which are functions of the layout of turbines. In this study we investigate the hydrodynamics of turbines in an infinitely large array with aligned or staggered layouts for a range of streamwise and lateral turbine spacing. First, we present a theoretical analysis based on an extension of the Linear Momentum Actuator Disc Theory (LMADT) for perfectly aligned and staggered layouts, employing a hybrid inviscid-viscous approach to account for the local blockage effect within each row of turbines and the viscous (turbulent) wake mixing behind each row in a coupled manner. We then perform Large-Eddy Simulation (LES) of open-channel flow for 28 layouts of tidal turbines using an Actuator-Line Method (ALM) with doubly periodic boundary conditions. Both theoretical and LES results show that the efficiency of turbines (or the power of turbines for a given bulk velocity) in an aligned array decreases as we reduce the streamwise turbine spacing, whereas that in a staggered array remains high and may even increase due to the positive local blockage effect (causing the local flow velocity upstream of each turbine to exceed the bulk velocity) if the lateral turbine spacing is sufficiently small. The LES results further reveal that the amplitude of wake meandering tends to decrease as we reduce the lateral turbine spacing, which leads to a lower wake recovery rate in the near-wake region. These results will help to understand and improve the efficiency of tidal turbines in future large arrays, even though the performance of real tidal arrays may depend not only on turbine-to-turbine interactions within the array but also on macro-scale interactions between the array and natural tidal currents, the latter of which are outside the scope of this study. |
| spellingShingle | Ouro, P Nishino, T Performance and wake characteristics of tidal turbines in an infinitely large array |
| title | Performance and wake characteristics of tidal turbines in an infinitely large array |
| title_full | Performance and wake characteristics of tidal turbines in an infinitely large array |
| title_fullStr | Performance and wake characteristics of tidal turbines in an infinitely large array |
| title_full_unstemmed | Performance and wake characteristics of tidal turbines in an infinitely large array |
| title_short | Performance and wake characteristics of tidal turbines in an infinitely large array |
| title_sort | performance and wake characteristics of tidal turbines in an infinitely large array |
| work_keys_str_mv | AT ourop performanceandwakecharacteristicsoftidalturbinesinaninfinitelylargearray AT nishinot performanceandwakecharacteristicsoftidalturbinesinaninfinitelylargearray |