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INTAKE LOSSES, CONCRETE CONDUITS, SHEET 221-1

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HYDRAULIC DESIGN CRITERIA
SHEET 221-1
CONCRETE CONDUITS
INTAKE LOSSES

1. Chart 221-1. The chart presents intake losses determined from model and prototype investigations of single, double, and triple intakes. It is only applicable to conduits flowing full.

2. Theory. For design purposes intake losses include trashrack, entrance, gate-slot, transition, and friction losses throughout the intake section. The total intake loss expressed as a function of the velocity head in the conduit proper is

he = Ke ( v^2 / 2g )

where,
he = intake loss, ft
Ke = loss coefficient
v= average velocity in conduit proper, ft/sec
g= acceleration due to gravity, ft/sec^2

3. Accurate experimental determination of intake losses is dependent upon the conduit being of sufficient length to permit a uniform friction gradient to be established based on fully developed turbulence. The intake loss is the total available head minus the velocity head and the friction loss of the conduit.

4. Basic Data. Chart 221-1, which summarizes the best available data, was developed from results of model and prototype investigations of conduits of sufficient length for turbulence to become fully developed. The data selected from model and prototype investigations for use in determining intake losses for the three types of intakes are described below.

a. Single intake. The Pine Flat Dam(1) data used are prototype pressures observed in a rectangular concrete conduit. Other data(2) were obtained during a laboratory study of the effect of artificial stimulation of the turbulent boundary layer in a rectangular conduit conducted under Corps of Engineers Engineering Studies Item 802, Conduit Intake Model Tests. The laboratory intake section contained no gate slots. Data concerning the effects of gate slots on intake losses were obtained in special tests made during the Bull Shoals Dam(3) model study; the data indicate that these effects are negligible.

b. Double intake. Prototype pressure data were obtained at Denison(4) and Fort Randall Dams.(5) The Denison(6) and Fort Randal1(7) models were built to a scale of 1 to 25. The friction losses in the Fort Randall model appeared normal. Those in the Denison model appeared excessively low. However, the relation between model and prototype intake losses is consistent.

c. Triple intake. The Tionesta model(8) data are the only known data resulting from a study of a triple intake to a conduit of sufficient length to permit turbulence to become fully developed.

5. References.

(1) U. S. Army Engineer Waterways Experiment Station, CE, Vibration, Pressure and Air-Demand Tests in Flood-Control Sluice, Pine Flat Dam, Kings River, California. Miscellaneous Paper No. 2-75, Vicksburg, Miss., February 1954.

(2) _________, The Effect of Artificial Stimulation of the Turbulent Boundary Layer in Rectangular Conduits. Miscellaneous Paper No. 2-160, Vicksburg, Miss., March 1956

(3) _________, Model Studies of Conduits and Stilling Basin, Bull Shoals Dam, White River, Arkansas. Technical Memorandum No. 2-234, Vicksburg, Miss., June 1947.

(4) _________, Pressure and Air Demand Tests in Flood-Control Conduit, Denison Dam, Red River, Oklahoma and Texas. Miscellaneous Paper No. 2-31, Vicksburg, Miss., April 1953.

(5) _________, Flow Characteristics in Flood-Control Tunnel 10, Fort Randall Dan, Missouri River, South Dakota; Hydraulic Prototype Tests. Technical Report No. 2-626, Vicksburg, Miss., June 1963.

(6) _________, Hydraulic Model Studies of the Control Structures for the Denison Dam, Red River. Technical Memorandum No. 161-1, Vicksburg, Miss., April 1940.

(7) _________, Spillway and Outlet Works, Fort Randall Dam, Missouri River, South Dakota; Hydraulic Model Investigation. Technical Report No. 2-528, Vicksburg, Miss., October 1959.

(8) Carnegie Institute of Technology , Report on Hydraulic Model Tests of Spillway and Outlet Works for Tionesta Creek Reservoir Dam, Tionesta, Pennsylvania. Hydraulic Laboratory, Pittsburgh, Pa., September 1938.

*** 참고문헌[References] ***

USACE, Hydraulic Design Criteria, SHEET 221-1, CONCRETE CONDUITS, INTAKE LOSSES

he = Ke * ( v^2 / (2 * g) )

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INTAKE LOSSES, CONCRETE CONDUITS, SHEET 221-1

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