Flow Rate Sensitivity Due to Parshall Flumes Staff Gauge Locations and Entrance Wingwall Configuration

Document Type

Article

Journal/Book Title/Conference

Journal of Irrigation and Drainage Engineering

Volume

137

Issue

2

Publisher

American Society of Civil Engineers

Publication Date

1-14-2011

First Page

94

Last Page

101

Abstract

Parshall flume tests were conducted to determine the sensitivity on indicated flow rate resulting from improperly located staff gauges and differing entrance conditions to the flume. An acrylic 2 ft (61 cm) Parshall flume was constructed to specified design dimensions and installed level in an 8 ft (243.8 cm) wide testing flume at the Utah Water Research Laboratory. Multiple stilling wells and two sliding point gauges were used to determine the head measurements from stilling well ports and water surface elevations along the wall and down the center of the converging approach section of the flume for multiple flow rates. The recommended radius wingwall, a 45° wingwall and no wingwall were also tested with and without offsets at the entrance to the flume. The laboratory tests indicated that head measurements taken at locations other than the location specified by Parshall (2/3A) can produce up to 60% errors in the flow measurement. Additionally, the lack of wingwalls and the incorrect design and installation of wingwalls cause standing waves to form in the throat of the flume which also affects flow measurement accuracies.

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