Measurements of Turbulence at Two Tidal Energy Sites in Puget Sound, WA

Thomson, Jim; Polagye, Brian; Durgesh, Vibhav; Richmond, Marshall C.

doi:10.1109/joe.2012.2191656

Cited by 207 publications

(203 citation statements)

References 32 publications

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“…This is assumed to be a consequence of the transition to the upper water column that is identified as a region of poor-quality data. This 10% turbulence intensity value is consistent with many sites studied in the literature concerning quantification of turbulence for ocean current and tidal power [21,22].…”

Section: Turbulence Intensity Metricsupporting

confidence: 89%

Engineering analysis of turbulent flow measurements near Kuchinoshima Island

2018

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Ocean current measurements from near Kuchinoshima Island are analyzed to consider turbulence characteristics with regard to the engineering design of an ocean current turbine. The location of the measurements is offshore of Kuchinoshima in the Tokara Strait within the path of the Kuroshio Current. The measurement campaign was from January 15 to 16, 2016 using the Nortek Signature 500 ADCP and Nortek Vector ADV. Turbulence characteristics of turbulence intensity, integral timescale, and integral length scale are evaluated at 1 m increments above the seabed. Doppler noise removal is performed and power density spectrums are presented. The findings will lead to more accurate loading calculations and simulations for performance evaluation.

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Section: Turbulence Intensity Metricsupporting

confidence: 89%

Engineering analysis of turbulent flow measurements near Kuchinoshima Island

2018

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“…The range of turbulence conditions covers the expected turbulence intensities at tidal sites of approximately 10-15% [8], [9], although the length scales will likely be smaller due to the restrictions imposed by the flume size. However, it is not our intention to recreate the conditions at a specific tidal site, but to generate a range of turbulence intensities and length scales in which the turbine can operate to assess how they affect its performance and blade loads.…”

Section: Discussion and Summary Of Mapping Observationsmentioning

confidence: 96%

“…Turbulence has been identified as requiring further investigation for both single devices [6] and arrays of multiple devices [7]. Tidal flows are highly turbulent with a broad range of length scales, and intensities [8], [9]. Previous investigations have shown how the thrust coefficient, or mean (time averaged) thrust force, of a porous disc rotor simulator can vary by over 20% in turbulent flows with different turbulence characteristics [10].…”

Section: Introductionmentioning

confidence: 99%

Effects of turbulence on tidal turbines: Implications to performance, blade loads, and condition monitoring

Blackmore

Myers

Bahaj

2016

International Journal of Marine Energy

130

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Laboratory scale testing of tidal turbines has generated valuable datasets to support optimised turbine design and numerical model validation. However, tidal sites are highly turbulent with a broad range of length scales and turbulence intensities that are site specific. In this work we describe an experimental campaign using static grids to generate turbulence and investigate its impact on a model tidal turbine in a circulating water flume. Length scales, energy spectra and turbulence dissipation rates are first considered for centre point measurements before full flow characterisation of the ambient conditions across the turbine rotor area. Six different cases were chosen to observe the performance of a 1/20 th scale 0.8m diameter turbine subjected to these flows. The rotor thrust and torque, and flapwise and edgewise blade root bending moments were measured. It was found that the thrust and power coefficients were sensitive to the estimate of ambient velocity. In the most extreme case the Betz limit could be 'exceeded' depending on which estimate of ambient velocity was used. Overall variations in the peak power coefficient of over 10% were observed, demonstrating the significance turbulence has on turbine performance. It was also found that there is a strong correlation between fluctuations in blade root bending moments and the rotor loads. As a result we proposed that fatigue loads acting on the blades may be estimated from the fluctuations in power output of the turbine. Therefore maintenance operations maybe optimised from real-time fatigue monitoring of blade loads without the need to install additional instrumentation on the turbine blades. Under this proposed regime the cost of energy will be reduced due to reductions in turbine costs and following optimisation of the maintenance requirements and operational costs. This could also improve turbine reliability which would have significant implications for large multi turbine arrays.

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“…Despite tremendous effort to observe cavitation and turbulence in real environmental conditions, little has been successfully achieved that can easily be repeated. Today, the common way to measure underwater turbulence is by utilizing Acoustic Doppler Current Profilers (ADCPs) (e.g., [24]) and Phased Array Doppler Sonar (PADS). However, not many studies of underwater turbulence and cavitation have been done using multibeam sonar (MBS) or dual-beam sonar (DBS) systems.…”

Section: Introductionmentioning

confidence: 99%

Use of Multibeam and Dual-Beam Sonar Systems to Observe Cavitating Flow Produced by Ferryboats: In a Marine Renewable Energy Perspective

Francisco

Carpman

Temiz

et al. 2017

JMSE

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Abstract:With the prospect to deploy hydrokinetic energy converters in areas with heavy boat traffic, a study was conducted to observe and assess the depth range of cavitating flow produced by ferryboats in narrow channels. This study was conducted in the vicinity of Finnhamn Island in Stockholm Archipelago. The objectives of the survey were to assess whether the sonar systems were able to observe and measure the depth of what can be cavitating flow (in a form of convected cloud cavitation) produced by one specific type of ferryboats frequently operating in that route, as well as investigate if the cavitating flow within the wake would propagate deep enough to disturb the water column underneath the surface. A multibeam and a dual-beam sonar systems were used as measurement instruments. The hypothesis was that strong and deep wake can disturb the optimal operation of a hydrokinetic energy converter, therefore causing damages to its rotors and hydrofoils. The results showed that both sonar system could detect cavitating flows including its strength, part of the geometrical shape and propagation depth. Moreover, the boat with a propeller thruster produced cavitating flow with an intense core reaching 4 m of depth while lasting approximately 90 s. The ferry with waterjet thruster produced a less intense cavitating flow; the core reached depths of approximately 6 m, and lasted about 90 s. From this study, it was concluded that multibeam and dual-beam sonar systems with operating frequencies higher than 200 kHz were able to detect cavitating flows in real conditions, as long as they are properly deployed and the data properly analyzed.

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Measurements of Turbulence at Two Tidal Energy Sites in Puget Sound, WA

Cited by 207 publications

References 32 publications

Engineering analysis of turbulent flow measurements near Kuchinoshima Island

Engineering analysis of turbulent flow measurements near Kuchinoshima Island

Effects of turbulence on tidal turbines: Implications to performance, blade loads, and condition monitoring

Use of Multibeam and Dual-Beam Sonar Systems to Observe Cavitating Flow Produced by Ferryboats: In a Marine Renewable Energy Perspective

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