Single-Beam Acoustic Doppler Profiler and Co-Located Acoustic Doppler Velocimeter Flow Velocity Data

Abstract

Acoustic Doppler Profilers (ADPs) are routinely used to measure flow velocity in the ocean, enabling multi-points measurement along a profile while Acoustic Doppler Velocimeters (ADVs) are laboratory instruments that provide very precise point velocity measurement. The experimental set-up allows laboratory comparison of measurement from these two instruments. Simultaneous multi-point measurements of velocity along the horizontal tank profile from Single-Beam Acoustic Doppler Profiler (SB-ADP) were compared against multiple co-located point measurements from an ADV. Measurements were performed in the FloWave Ocean Energy Research Facility at the University of Edinburgh at flow velocities between 0.6 ms − 1 and 1.2 ms − 1 . This paper describes the data; the analysis of the inter-instrument comparison is presented in an associated Sensors paper by the same authors. This data-set contains (a) time series of raw SB-ADP uni-directional velocity measurements along a 10 m tank profile binned into 54 measurements cells and (b) ADV point measurements of three-directional velocity time series recorded in beam coordinates at selected locations along the profile. Associated with the data are instrument generated quality data, metadata and user-derived quality flags. An analysis of the quality of SB-ADP data along the profile is presented. This data-set provides multiple contemporaneous velocity measurements along the tank profile, relevant for correlation statistics, length-scale calculations and validation of numerical models simulating flow hydrodynamics in circular test facilities.

On the Use of a Single Beam Acoustic Current Profiler for Multi-Point Velocity Measurement in a Wave and Current Basin

“…Section 3.1 presents the results from the inter-instrument comparison at the co-located measurements points from Table 3 for a nominal tank flow velocity of 0.8 ms −1 . The ADV data used from the comparison at 0.8 m/s were collected during the SuperGen Marine tidal array project [ 8 , 29 ], the remaining ADV data and all the SB-ADP data were collected specifically for this work and are presented in detail in [ 35 ]. Twenty-seven co-located measurements were analysed along an 8 m profile, with three SB-ADP measurement cells subsequently removed after further analysis [ 35 ].…”

“…The ADV data used from the comparison at 0.8 m/s were collected during the SuperGen Marine tidal array project [ 8 , 29 ], the remaining ADV data and all the SB-ADP data were collected specifically for this work and are presented in detail in [ 35 ]. Twenty-seven co-located measurements were analysed along an 8 m profile, with three SB-ADP measurement cells subsequently removed after further analysis [ 35 ]. Section 3.2 presents the results from the inter-instrument comparison across a range of tank nominal flow velocities at four locations distributed across the profile.…”

“…Figure 4 shows for a nominal tank flow velocity of 0.8 ms -1 , the mean and standard deviation of the co-located measurements of velocity from the ADV and SB-ADP along the profile in ( a ) and the difference between mean measurements along the profile in ( b ). The gap between 2.7 m and 3.9 m is caused by the additional analysis, as presented in [ 35 ]. The first co-located measurement indicates a higher bias than that observed on the rest of the profile (4.5% of the ADV velocity).…”

“…There were 24 co-located ADV/SB-ADP measurement locations along an 8.3 m profile. SB-ADP data and additional details are contained within [ 34 , 35 ].…”

“…Inter-instrument comparison was conducted at three further nominal tank current velocities of 0.6 ms −1 , 1.0 ms −1 , and 1.2 ms −1 , at four target locations distributed along the x-axis of the horizontal profile, in order to assess the agreement over a range of flow speeds at which the facility operates. Further details about both ADV and SB-ADP data can be found in [ 35 ]. However, following test completion and after correspondence with the instrument manufacturer, SB-ADP cell centres were found to be offset by half a cell length relative to original positioning.…”