INVESTIGATION OF THE EFFECT OF TURNOUT GEOMETRY ON THE REGISTRATION ACCURACY OF A PROPELLER-TYPE OPEN FLOWMETER,
Abstract
Measurement of the indicated discharge of a 12in. propeller-type open flowmeter in laboratory tests showed that the deviations caused either by the change in outlet geometry or by the change in submergence of the outlet pipe did not exceed the normally specified meter accuracy of + or -2%. The meter was calibrated with the outlet pipe discharging first into an open box (unconfined outlet) and then into a confined outlet, similar to a USBR farm-turnout design. Calibrations were made for 2 water depths in each outlet type to study the effect of submergence on the indicated discharge. Over the rated range of discharges (0.45 to 4.5 cfs) the difference in indicated discharge for the 2 outlets was less than 1.7% with the maximum deviation occurring at the lowest discharge (0.45 cfs). The maximum variation in indicated discharge caused by an increase in submergence of the outlet pipe of 1.3 pipe diameters was less than 0.6% for the open box and less than 2.0% for the farm turnout. The effect of changes in submergence of the outlet on indicated discharge is not significant, as indicated by best-fit calibration curves, provided that the turnout pipe exit remains fully submerged. The farm turnout tested is probably the minimum size that should be used, because any decrease in outlet well size would cause increased turbulence in the canal section and could cause erosion of the downstream embankment. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 28, 1965
- Accession Number
- AD0466569
Entities
People
- C. E. Brockway
Organizations
- United States Bureau of Reclamation