Head-discharge Relationship Research Articles

Rating of Z-Section, Steel-Sheet Piling Drop Structures

ABSTRACT THE free-flow and submerged head-discharge re-lationships for a Z-section, steel-sheet metal piling, water-level control structure were determined using a physical model. A head-discharge relationship, developed using rectangular weir flow data, did not ade-quately predict the discharge for the sinuous weir formed by the Z-section pilings. Use of the sinuous length as the crest length may be adequate for low flow computations, and the weir opening width as the crest length may be adequate for high flow computations. In the transition range, where the effective crest length changes from the sinuous length to the weir opening width, the discharge cannot be adequately predicted. This change in crest length is not instantaneous, and cannot be predicted with present data. An equation developed by Villemonte from a series of tests on submerged sharp-crested weirs adequately predicted the submerged discharge.

The Performance of a Modified Coshocton-Type Runoff Sampler

ABSTRACT THIS paper presents the procedure, analysis, and re-sults of tests with a modified N-2 Coshocton-type runoff sampler under different approach conditions. The sampler performance is compared to the standard design sampler performance, and the observed head-discharge relationships are compared with the standard rating tat/le and a rating developed by Gwinn and Parsons (1976). The effects of the modification on the sampler performance are discussed.

Prototype Spillway Performance Verification

The flow performance of a prototype closed conduit spillway which could not be explained analytically was verified by a physical model. During the falling stage of the outflow from the reservoir, full conduit flow was observed in the Marsh Creek spillway even though the pool level was below the spillway crest. Engineers inspecting the spillway could not agreeably explain the flow performance. A physical model of the prototype was built and tested to verify the prototype performance. Tested with open and closed air vents, the model demonstrated the hysteresis shown in the falling limb of the prototype head-discharge relationship and the siphon-regulated flow observed in the prototype. Model observations indicate that the prototype flow control problem is the result of inadequate venting of the covered-top drop inlet.

Performance Characteristics of Manure Slurry Pumps

ABSTRACT TWO suction lift helical rotor pumps, one submerged and one suction lift centrifugal pump both with a chopper and agitator, and one suction life centrifugal pump were tested using dairy cattle manure at low (0,5 percent), medium (4 percent) and high (7 percent) solids content. Performance curves for each pump illus-trate the head-discharge relationship, power consump-tion, and pump efficiency. Based on these results, recom-mendations are made on their suitability for various applications.

Quadrant-Plate Weir

The simple weir flow equation was numerically integrated for a quadrant-plate weir to show that the head-discharge relationship for this weir is approximately linear. The approximation to linearity can be greatly improved by a judicious choice of the parameters that determine the weir geometry. The results of experiments on selected weirs were in agreement with the predicted relationships. The coefficient of discharge for the quadrant-plate weir is a function of the approach channel Froude number. For very low Froude numbers (F d asymptotically approaches a value of 0.61.

The use of long-throated flumes to measure flows in irrigation and drainage canals

Presented in this paper is a set of easy-to-use formulae that give an accurate head-discharge relationship for long-throated flumes with a prismatic throat cross-section. The method by which the formulae have been derived is the same for all long-throated flumes, regardless of the shape of their throat cross-sections. As a result the value of the discharge coefficient is independent of this shape and is a function of the ratio of the upstream energy head over the flume to the flow-wise length of the throat. The formulae and coefficient values in this paper also apply to broad-crested weirs with rounded upstream nose.

Water Line Transmission of Control Information

The hydrodynamic relations of flow and pressure are used to transmit information over a ten mile long, small diameter transmission main. The system includes an inlet rate of flow controller on the terminal reservoir, so designed that the rate of inflow into the reservoir is dependent only on the level of the water in the reservoir, and will not normally be affected by the pressure in the transmission main. Selection of the well pump being used is determined by the rate of flow of the water into the reservoir. The output pressure of the pump is regulated by varying the speed of the engine driving the pump. The engine speed is controlled by a preselected head-discharge relationship of the transmission main, and is controlled in such a manner that the pressure on the control valve at the reservoir inlet will be between 20 and 40 psi. The entire system operates with only an occasional checking or mechanical service call.