Subcritical Contraction for Improved Open-Channel Flow Measurement Accuracy with an Upward-Looking ADVM
Copyright © 2010 American Society of Civil Engineers. The definitive version is available at http://dx.doi.org/10.1061/(ASCE)IR.1943-4774.0000224.
Acoustic Doppler velocity meters (ADVMs) provide an alternative to more traditional flow measurement devices and procedures such as flumes, weirs, and stage rating for irrigation and drainage canals. However, the requirements for correct calibration are extensive and complex. A three-dimensional computational fluid dynamics (CFD) model was used to design a subcritical rapidly varied flow contraction that provides a consistent linear relationship between the upward-looking ADVM sample velocity and the cross-sectional average velocity in order to improve ADVM accuracy without the need for in situ calibration. CFD simulations validated the subcritical contraction in a rectangular and trapezoidal cross section by showing errors within +1.8 and -2.2%. Physical testing of the subcritical contraction coupled with an upward-looking ADVM in a large rectangular flume provided laboratory validation with measurement errors within +-4% without calibration.
Daniel Howes, Charles M. Burt, and Brett F. Sanders. "Subcritical Contraction for Improved Open-Channel Flow Measurement Accuracy with an Upward-Looking ADVM" Journal of Irrigation and Drainage Engineering 136.9 (2010): 617-626.
Available at: http://works.bepress.com/djhowes/6