Showing papers on "Weir published in 1987"

Flow Over Sharp‐Crested Plate Weirs

Abstract: For flow past a two‐dimensional sharp‐crested weir located at the end of a horizontal rectangular channel, experimental results related to velocity and pressure distributions in the region of the nappe close to the weir crest section and the pressure distribution on the weir face were obtained. Based on experimental results and simplified theoretical considerations, a general relationship between the weir discharge coefficient Cd and the parameter H/W (or W/H) is determined using the momentum principle. The present experimental results corroborate the proposed relationship for the weir discharge coefficient.

Channel degradation in the middle Arve river, France

Abstract: Man-induced channel changes within Alpine alluvial rivers are investigated. For the middle Arve river, a series of long profiles surveyed between 1856 and 1981 show deep and rapid degradation since the beginning of the 1950s. This tendency is related to gravel extraction, weir construction, and embankment, and is shown to characterize Alpine rivers.

Gas extraction outlet for wastewater settling tank

Abstract: An outlet for extracting noxious gases generated in a settling tank containing a pool of wastewater, the outlet including an effluent trough supported at a raised position in the pool against the tank wall. The trough is provided with a side wall parallel to the tank wall and lying somewhat below the surface of the pool, a weir being supported on this side wall and extending upwardly therefrom to permit clarified water from the surface region of the pool to spill over into the trough. Overlying the trough and the weir is a flat walk plate that extends horizontally from the tank to the upper edge of a vertical sidewall which extends downwardly into the pool, the sidewall together with the walk plate acting to confine noxious gases emitted into the region above the trough and the weir to prevent their discharge into the atmosphere. The walk plate includes a hatch cover section providing access to the weir when it becomes necessary to scrub and clean the weir.

Swimming pool water skimming and vacuuming apparatus

Abstract: An automatic pool vacuum unit is connected to a skimmer housing by a vacuum housing fitted in an inverted U-shaped opening in the skimmer weir, open to the bottom of the weir. In order to avoid interfering with normal pivoting of the buoyant weir by the vacuum housing, the housing in planes at right angles to the pivotal axis of the weir has upper outlines that are arcuate about that axis, and the vacuum housing has an outline matching the outline of the inverted U-shaped opening in planes through the weir pivotal axis, so that the vacuum housing substantially fits and substantially seals the weir opening as the weir pivots. A removable cover over the debris-collecting basket in the skimmer housing has an opening connecting with the vacuum housing and an adjustable opening for skimmer water spilling over the top of the weir. The vacuum housing is removably secured to the cover to facilitate removal of the debris collecting basket.

Apparatus for the melting of metals

Abstract: An apparatus for melting metals in a vacuum chamber has a weir box (1), electron beam generators disposed above the weir box, and a crucible for the withdrawal of the melt flowing out of the weir box. A weir or sill is disposed in the trough athwart the length thereof, and it divides the trough into two basins and is situated underneath the one electron-beam source. The melt flowing from the one basin into the other runs in a thin film over the top of the weir or notch while the titanium nitrite in the melt is dissolved.

Effects of Semi-Impoundment on Fish and Crustacean Nursery Use: Evaluation of a Solution

Abstract: Semi-impoundment of the marsh is one of the primary 'solutions' currently recommended to combat coastal marsh erosion, and also to improve habitat for waterfowl, alligators and furbearers. A 70-hectare marsh pond was leveed to create two nearly identical 35-hectare ponds. A fixed-crest weir was placed in the outlet of only one of the ponds. All fishes and crustaceans emigrating from the two ponds were trapped continuously and the traps were emptied daily. The trapping continued for 2 years, with the weir being switched to the outlet of the other pond after the first year. Comparisons of catches from the weired and non-weired ponds showed that the weir caused substantial reductions in both the number and total weight of most of the important estuarine-dependent fishes and crustaceans migrating back toward the Gulf. A subsequent test indicated semi-impoundment by a vertically slotted weir would allow more fisheries export.

Furrow Irrigation Using Canal Side Weirs

Abstract: The potential of canal side weirs for uniform water delivery to irrigation furrows and system flexibility is assessed. Weir discharge uniformity is affected by: (1) Canal velocity and weir entrance conditions; (2) variations in weir crest construction elevations; and (3) variations in water surface elevations along the distribution canal. For sharp-entranced weirs, model studies showed that the decrease in canal flow velocity down a typical distribution reach can result in an increase in weir discharge up to 15%. This velocity effect is significantly dampened by using a streamlined entrance to the weir. Field data on weir crest elevations have a standard deviation of about 3 mm, which translates into 6–8% weir discharge variation at normal discharge settings. A computer model of distribution canal flows indicates weir discharge uniformity is improved by shortening the length of the reach, reducing the required weir discharge setting, and increasing canal size. A design guideline is developed for the system.

Apparatus for measuring weir height of flexible film weir

Abstract: PURPOSE:To accurately measure the height of a rubber weir within a short time, by detecting a cross-sectional shape on the basis of the height of the rubber weir at each specific point in the rubber weir by utilizing an output signal obtained by electrically converting the paid out length of a long object provided to the main body of a measuring instrument. CONSTITUTION:With respect to one measuring instrument main body A1 of one set of measuring instrument main bodies 11, the other one A2 is arranged so as to leave a definite distance l0 in the flow direction of a river and long objects 16 are paid out from A1, A2 of one set of the measuring instrument main bodies 11 in such a state that the leading ends thereof are united at one specific point P on the inner wall surface of a rubber weir 1. In this case, the paid out length I of the long object 16 reaching the specific point P from A1 is set to l1 and the paid out length of the long object 16 reaching the specific point from A2 is set to l2 and both lengths are read by the electrical detectors mounted in the measuring instrument main bodies 11 to make it possible to calculate the height of the point P. In this case, because the calculated result is stored in a computer 18 or recorded on a printer, the height of the weir can be determined with high accuracy within a short time.

Flexible thin film elevating and falling weir

Abstract: This invention is a flexible thin film elevating and falling weir located at the top of a concret structure in the water. The discharging pipe has an opening located in the lowest place of the inner part of the enclosing layer for the facility of the perfect falling of the weir to let the water flow freely.

Long Crested Weirs

Abstract: A method has been developed to integrate and evaluate the head relationship between canal weirs and turnouts. The objective is to minimize flow variations through the turnout and at the same time permit the canal flow to vary to meet the changing needs of the system. A step-by-step procedure is presented for the computations of the required length of a long crested weir. Using the long crested weir results in a more stable flow rate through the turnout with less labor. The benefit to the water user is that less labor is required to manage or control the water.

Weir level measuring device for flexible diaphragm weir

Abstract: PURPOSE:To exactly measure the level of a weir without being influenced by the change in water level and without worrying about the damage of the weir, by setting the generator and the receiver of laser, and by computing the level of the weir in triangulation system from a receiving state determined by the receiver. CONSTITUTION:On a river concrete unit 5 between the lower half section edge 2 and the upper half section edge 3 of a rubber weir 1, a rectangular concave section 10 is formed, and a base 11 is inserted. Then, on the one end section of a supporting member 15, a semiconductor laser 21 is mounted with a laser beam exit directed upwards, and on the other end section, a receiving lens 22 and a semiconductor position detecting element 23 are mounted. Then, laser beam is emitted from the semiconductor laser 21, and the semiconductor position is read through the picture element signal of the detecting element 23, and the level of a point P is computed. As a result, even if the form of the cross section of the weir is changed along with the change of water level, the level of the weir can be exactly measured.

Seepage barrages underneath

Abstract: A subsidiary weir with a sloping middle apron may be constructed downstream from each of the existing barrages on the River Nile in Egypt to secure its stability against the increase in effective heads. The problem is mathematically solved by a conformal mapping technique. Formulas are obtained to calculate the uplift pressures acting on the existing barrage and the subsidiary weir. Also formulas are derived to calculate the exit gradients along the intermediate filter and the downstream bed. We calculate the seepage characteristics for a wide range of boundary conditions, plot the results in the form of curves, and analyze them. Keywords: Egypt; barrages; subsidiary weirs; seepage; uplift pressures