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Title: Outlet works for Site 16, Papillion Creek and tributaries, Nebraska : hydraulic model investigation
Authors: United States. Army. Corps of Engineers. Omaha District.
Fletcher, Bobby P.
Keywords: Hydraulic models
Outlet works
Papillion Creek
Hydraulic structures
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; H-73-17.
Description: Technical Report
Abstract: The Site 16 outlet works structure is typical of those that will be utilized for flood control in a series of 20 dams and reservoirs proposed for construction on tributaries of Papillion Creek within Douglas, Sarpy, and Washington Counties, Nebr. The recommended project plan for the Site 16 reservoir includes the construction of an earth dam, an uncontrolled spillway, and an uncontrolled outlet works consisting of an intake structure and conduit through the dam. Although design criteria for two-way drop inlets have been developed by previous St. Anthony Falls Hydraulic Laboratory and Waterways Experiment Station model studies, the model study reported herein was considered warranted since the Site 16 outlet works included structural features that had not been studied in the previous model studies, namely, low- level intakes, an access shaft, a change in both conduit grade and alignment, and an orifice-control device located at the conduit entrance. A 1:7.5-scale model was utilized for specific study of the hydraulic performance to be anticipated with the Site 16 structure. In addition, a 1:10-scale model was utilized to determine generalized conditions required for the existence of flow control at entry to the riser shaft of similar outlet works structures. Results of the study were as follows : (A.) Intermingling and instability of the nappes as flow passed through the low-level intakes were eliminated by extending the divider wall down the riser shaft a distance of 4 ft to provide a barrier between the nappes. (B.) The 6-ft-diam access shaft was reduced to 3 ft, and by repositioning the shaft from the center of the bend to a point 6ft upstream from the upstream end of the bend, turbulence within the access shaft that tended to induce vibration of the shaft was reduced. These measures were also beneficial in permitting the release of air entrained within the flow that created slug flow within the conduit when the conduit flowed full upstream of the access shaft. (C.) A dimensionless equati on was developed for calculating the discharge capacity of roof constrictions to establish orifice control at a conduit entrance. (D.) Equations were developed for calculating the discharge characteristics associated with weir and orifice control at the intake of similar outlet works.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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