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Title: High-resolution velocimetry in energetic tidal currents using a convergent-beam acoustic Doppler profiler

An array of convergent acoustic Doppler velocimeters has been developed and tested for the high resolution measurement of three-dimensional tidal flow velocities in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use diverging acoustic beams emanating from a single instrument. This is achieved using converging acoustic beams with a sample volume at the focal point of 0.03 m3. The array is also able to simultaneously measure three-dimensional velocity components in a profile throughout the water column, and as such is referred to herein as a converging-beam acoustic Doppler profiler (CADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational Alstom 1MW DeepGen-IV Tidal Turbine. This proof-of-concept paper outlines system configuration and comparison to measurements provided by co-installed reference instrumentation. Comparison of CADP to standard ADP velocity measurements reveals a mean difference of 8 mm/s, standard deviation of 18 mm/s, and order-of-magnitude reduction in realizable length-scale. CADP focal point measurements compared to a proximal single-beam reference show peak cross-correlation coefficient of 0.96 over 4.0 s averaging period and a 47% reduction in Doppler noise. The dual functionality of themore » CADP as a profiling instrument with a high resolution focal point make this configuration a unique and valuable advancement in underwater velocimetry enabling improved turbulence, resource and structural loading quantification and validation of numerical simulations. Alternative modes of operation have been implemented including noise-reducing bi-static sampling. Since waves are simultaneously measured it is expected that derivatives of this system will be a powerful tool in wave-current interaction studies.« less
 [1] ;  [2] ;  [2]
  1. Univ. of Edinburgh, Scotland (United Kingdom)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0957-0233; WC0100000
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Measurement Science and Technology; Journal Volume: 26; Journal Issue: 08
IOP Publishing
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
58 GEOSCIENCES; 47 OTHER INSTRUMENTATION Acoustic Doppler Velocimetry; Tidal Currents; Turbulence; ADP