American Society of Civil Engineers


Subcritical Contraction for Improved Open-Channel Flow Measurement Accuracy with an Upward-Looking ADVM


by Daniel J. Howes, (corresponding author), M.ASCE, (Senior Irrigation Engineer, Irrigation Training and Research Center, California Polytechnic State Univ., San Luis Obispo, CA 93407 E-mail: djhowes@calpoly.edu), Charles M. Burt, M.ASCE, (Professor, Dept. of BioResource and Agricultural Engineering, and Chair, Irrigation Training and Research Center, California Polytechnic State Univ., San Luis Obispo, CA 93407. E-mail: cburt@calpoly.edu), and Brett F. Sanders, M.ASCE, (Professor, Dept. of Civil and Environmental Engineering, Univ. of California, Irvine, CA 92697. E-mail: bsanders@uci.edu)

Journal of Irrigation and Drainage Engineering, Vol. 136, No. 9, September 2010, pp. 617-626, (doi:  http://dx.doi.org/10.1061/(ASCE)IR.1943-4774.0000224)

     Access full text
     Purchase Subscription
     Permissions for Reuse  

Document type: Journal Paper
Abstract: 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.


ASCE Subject Headings:
Critical flow
Open channel flow
Flow measurement
Acoustic techniques
Doppler systems
Laboratory tests
Hydraulics

Author Keywords:
Open channel flow
Subcritical flow
Flow measurement
Acoustic techniques
Doppler systems
Laboratory tests
Hydraulics