Numerical performance analysis of acoustic Doppler velocity profilers in the wake of an axial-flow marine hydrokinetic turbine

Richmond, Marshall C.; Harding, Samuel F.; Romero-Gómez, Pedro

doi:10.1016/j.ijome.2015.05.004

Cited by 15 publications

(7 citation statements)

References 24 publications

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“…When utilising D-ADPs for turbulence analysis, consideration of these varying scales is required [26,27]. Doppler noise is an inherent feature of the acoustic Doppler measurement technique, and correction methods have been employed in this work as described in Section 3.5 [28,29].…”

Section: Summary Of the Acoustic Doppler Profiling Techniquementioning

confidence: 99%

Characterisation of Tidal Flows at the European Marine Energy Centre in the Absence of Ocean Waves

et al. 2018

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Abstract:The data analyses and results presented here are based on the field measurement campaign of the Reliable Data Acquisition Platform for Tidal (ReDAPT) project (Energy Technologies Institute (ETI), U. K. 2010-2015). During ReDAPT, a 1 MW commercial prototype tidal turbine was deployed and operated at the Fall of Warness tidal test site within the European Marine Energy Centre (EMEC), Orkney, U.K. Mean flow speeds and Turbulence Intensity (TI) at multiple positions proximal to the machine are considered. Through the implemented wave identification techniques, the dataset can be filtered into conditions where the effects of waves are present or absent. Due to the volume of results, only flow conditions in the absence of waves are reported here. The analysis shows that TI and mean flows are found to vary considerably between flood and ebb tides whilst exhibiting sensitivity to the tidal phase and to the specification of spatial averaging and velocity binning. The principal measurement technique was acoustic Doppler profiling provided by seabed-mounted Diverging-beam Acoustic Doppler Profilers (D-ADP) together with remotely-operable Single-Beam Acoustic Doppler Profilers (SB-ADP) installed at mid-depth on the tidal turbine. This novel configuration allows inter-instrument comparisons, which were conducted. Turbulence intensity averaged over the rotor extents of the ReDAPT turbine for flood tides vary between 16.7% at flow speeds above 0.3 m/s and 11.7% when considering only flow speeds in the turbine operating speed range, which reduces to 10.9% (6.8% relative reduction) following the implementation of noise correction techniques. Equivalent values for ebb tides are 14.7%, 10.1% and 9.3% (7.9% relative reduction). For flood and ebb tides, TI values resulting from noise correction are reduced in absolute terms by 3% and 2% respectively across a wide velocity range and approximately 1% for turbine operating speeds. Through comparison with SB-ADP-derived mid-depth TI values, this correction is shown to be conservative since uncorrected SB-ADP results remain, in relative terms, between 10% and 21% below corrected D-ADP values depending on tidal direction and the range of velocities considered. Results derived from other regions of the water column, those important to floating turbine devices for example, are reported for comparison.

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Section: Summary Of the Acoustic Doppler Profiling Techniquementioning

confidence: 99%

Characterisation of Tidal Flows at the European Marine Energy Centre in the Absence of Ocean Waves

et al. 2018

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“…The generation of the current data is based on two further standard assumptions [16], which are: Assumption 1: At each depth the current is constant and homogenous. Assumption 2: There is no vertical component to the current velocity.…”

Section: Currentsmentioning

confidence: 99%

“…Another source of error in ADP measurements is the beam misalignment in the instrument [15]. It has been demonstrated that the beam misalignment from its nominal beam angle can cause velocity errors [16], with Woodgate and Holroyd suggesting that the actual beam angle relative to vertical can deviate by 1 • or 2 • [17].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Error of Mean Representative Current Velocity Based on the Method of Bins for Tidal Turbines Using ADP Data

Rathnayake

Folley

Gunawardane

et al. 2020

JMSE

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Representing the velocity at a tidal energy extraction site in a standardized manner is essential for the development of the tidal energy sector. The International Electrotechnical Commission (IEC) have issued a technical specification to determine the mean representative current velocity (MRV) relative to a tidal energy converter (TEC). This method determines the MRV using an acoustic Doppler profiler (ADP). This is used to evaluate the power performance of a TEC and so can have a significant influence on the power performance uncertainties, due to the cubed relationship of the MRV and power. This paper investigates these uncertainties in the MRV by considering four sources of uncertainty in the ADP. These are turbulence intensity, tilt, Doppler noise and beam misalignment of an ADP. A synthetically generated dataset is used to define current velocity and profile using the characteristics of currents and ADP. The generated synthetic dataset is processed to calculate the MRV based on the standard IEC method. An alternative method to calculate the MRV, called the temporal-spatial method (TSM), is proposed and the two methodologies are used to assess the error of the MRV. A sensitivity analysis shows that the errors of the MRV based on the standard IEC method are always higher than the TSM. The biases in the MRV based on the different combinations of the uncertainty are investigated and it is found that the bias for the MRVs based on the TSM method is generally less than that of the IEC method.

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“…The MeyGen project in Scotland [12] is among the pioneering projects in which extracting tidal energy from tidal streams becomes operational and is also connected to the electric grid. In comparison, most other efforts have been largely focused on the earlier stage of tidal energy development, such as characterizing available tidal energy resources using computational models and testing MHK devices in the laboratory and at representative field-testing sites [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

A Tidal Hydrodynamic Model for Cook Inlet, Alaska, to Support Tidal Energy Resource Characterization

Wang

Yang

2020

JMSE

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Cook Inlet in Alaska has been identified as a prime site in the U.S. for potential tidal energy development, because of its enormous tidal power potential that accounts for nearly one-third of the national total. As one important step to facilitate tidal energy development, a tidal hydrodynamic model based on the unstructured-grid, finite-volume community ocean model (FVCOM) was developed for Cook Inlet to characterize the tidal stream energy resource. The model has a grid resolution that varies from about 1000 m at the open boundary to 100–300 m inside the Inlet. Extensive model validation was achieved by comparing model predictions with field observations for tidal elevation and velocity at various locations in Cook Inlet. The error statistics confirmed the model performs reasonably well in capturing the tidal dynamics in the system, e.g., R2 > 0.98 for tidal elevation and generally > 0.9 for velocity. Model results suggest that tides in Cook Inlet evolve from progressive waves at the entrance to standing waves at the upper Inlet, and that semi-diurnal tidal constituents are amplified more rapidly than diurnal constituents. The model output was used to identify hotspots that have high energy potential and warrant additional velocity and turbulence measurements such as East Foreland, where averaged power density exceeds 5 kw/m2. Lastly, a tidal energy extraction simulation was conducted for a hypothetical turbine farm configuration at the Forelands cross section to evaluate tidal energy extraction and resulting changes in far-field hydrodynamics.

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Numerical performance analysis of acoustic Doppler velocity profilers in the wake of an axial-flow marine hydrokinetic turbine

Cited by 15 publications

References 24 publications

Characterisation of Tidal Flows at the European Marine Energy Centre in the Absence of Ocean Waves

Characterisation of Tidal Flows at the European Marine Energy Centre in the Absence of Ocean Waves

Investigation of the Error of Mean Representative Current Velocity Based on the Method of Bins for Tidal Turbines Using ADP Data

A Tidal Hydrodynamic Model for Cook Inlet, Alaska, to Support Tidal Energy Resource Characterization

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