US2966777A - Dam - Google Patents

Description

Jan. 3, 1961 Filed May 8, 1956 F. s. R. DE BRITO FlLHO DAM 5 Sheets-Sheet 1 FIG.\

F. s. R DE BRITO FlLHO Jan. 3, 1961 DAM Filed May 8, 1956 3 Sheets-Sheet 2 Jan. 3, 1961 F. s. R. DE BRlTO FILHO 2,966,777

DAM

Filed May 8, 1956 3 sheets sheet 3 Flcticious F4 Dampers Disturbmg Forces nited States Patent DAM Francisco Saturnino Rodrigues de Brito Filho, Riode Janeiro, Brazil, assignor to 'Escritorio Saturnino de Brito, Rio de Janeiro, Brazil ,FiledjMay 8, 1956, Ser. No. 583,559 Claims priority, application Brazil May 10, 1955 11 Claims. (Cl. 6126) The present invention relates to the type of movable or rotating panel dams which operate automatically at certain predetermined discharges.

A review of the literature pertaining to the-subject, such as Aubert Barrages et Canalisations, 1949, page 182 et alia; Dehnert Wehr und Stauanlage, 1952, page 97; Press Wehre, "1954, page 140 et alia, will show that all conventional types, such as those devised by Thenard, Chanoine, Pasqueau, Girard, Carro, Bebout, Aubert, Dortmund- Union, Man, and the so-called double-trestle, fish-belly and rigid torsional cylinder types, operate automatically and mechanically. But these dams, when they collapse, have to lie on the river bottom at places provided therefor. The drawbacks of such an arrangement are well known, particularly in cases where there is a great deal of solid discharge, which is frequent in so many rivers.

Another drawback inherent in dams of said ypes is'the vibratory action of the panels, as mentioned by Dehnert and Press who have given thought to the matter and have suggested means for the elimination of the deleterious efiects.

The dam herein described and claimed embodies various technological improvements as regards, shape, arrangement, installation, automaticity and other operational features. Ihisapplication therefore pertains to a combination ,of .elements which provides extraordinary technical results, especially in that it eliminates several disada s f conven io a dams o th s me ype, r ver the more recentone no in Jti also mor easi y constructed.

.In ,the present application all the said faults of conn icnat dams have be n du y x in andhave best; eliminated .by the provision of a novel automatic glam which; has the following characteristics:

.A small resistance :t th :flo o wa r. in :th open position, in order to facilitate the passage of large flood discharges;

(2) Continuity of the discharge of solids during the whole-.cycle .of. operation of; the dam;

.(=3.-') iGreat vruggedness of profile and technical perfection of 2831116;

(4.) Sufficient slownessof movement in .opening and closing :in order better todampen the solitary positive ornegative wavescaused .by said movements;

.t(=5) Utmost reductionof panel vibration, in ,the ppm positionof the da a;

(6) Ease of pivoting on ,the bearings which should be placed as far away as possible from the solids discharge, to function as perfectly as possible;

(7) .Ease of construction and .maintenance. On examination of the problem, the applicant early ascertained the convemenceof adopting a panel profile of less hydraulic resistance, derivedfrom the Joukovsky profile.

One ofthe initial objectives was to reduce an excessive loss of head at very greatdischarges, with a type of dam devised-not to lie down on the river bed. However, laboratory tests led the applicant to introduce in the profile some modifications designed to render the'novel darn better suited for its purposes.

To begin with the applicant found out that profile inertia was a basic factor but when the dam was in the open position vibrational phenomena became very serious. In order to eliminate the said effects, the" applicant devised a series of internal troughs joining the upstream panel surface to the downstream surface, to -reduce the zone of influence of negative pressures on the downstream surface of the panel, when the panel is open, and also to promote, in the open panel, a reaction designed to generate a stabilizing tendency to combat the said vibrations. The model initially used and observed was made of concrete. In order to maintain the influence of inertia and the preponderance of weight the applicant altered the panel structure, building the lower part of concrete still, but using metal for the upper part, while still providing for the troughs (or channels). Enperiments showed furthermore that the troughs or channels should be continuous all along the rotating panel, in the direction of the dam, as distinguished from isolated troughs or channels between the upstream and downstream surfaces.

This form was further modified by introducing in the upper part of the panel rudders or baflles designed to combat the vibrations and to stabilize the dam when it is opened. The baffles are attached to the upper part of the panel, i.e., to the metal part thereof. The bafiles operate in connection with the crest which is formed of two diverging parts which start from the base of the baffles.

The arrangement of the crest is designed to subdivide and ventilatethe sheet of water flowing over the weir in the closed position of the dam. 7' The applicant also experimented with the installation of baffles or stops in-the sill structure of the dam foundation for securing the dam in the closed position, in order to provide for a continuous or discontinuous discharge below the dam under operating conditions. In order better to stabilize the darn, a metal counterweight--a metal cylinder--was also installed along the lower part of .the panel, bearing on the stops.

It was thus found that at the lower part of the dam, in the vicinity of the stops, elements could be provided, designed-to promote expansion of the liquid flow and then later a concentration of same, when necessary, under the lower panel face, in order to equalize the hydraulic actioniexerted on said panel. l

Experiments also showed that the control of solidsdischarge required placing, at the start of the counterslope, a grid designed to collect and retain large-sized materials carried by the mass of water.

*lnshort, a series of novel elements and arrangements had to be added to the Joukovsky profile, in accordance with laboratory experiments and the profile had to be adjusted for full compliance with the technical requirements.

Thus, it is the firsttime that the Ioukovsky profile has been used for a movable panel darn, with due adaptation to local conditions after technical study of the matter and technological researches.

Theme of said dam as a water level regulating device upstream from the point of installation is thus recommended in the following cases: i i i (a) For navigation purposes: in order to maintain upstream a minimnmdepth of water to accommodate the draught of standard vessels; V

(b) For navigation purposes: in order to control the height of falljn canal or river locks; i i

"(0) For;irrigation purposes: in order to maintain the upstream water level at an elevation that will not inter fere with the required underground water level of the surrounding country;

(d) For sanitation and landscaping purposes: in order to create in the dry season a lake from rivers flowing through cities;

(e) For water collection purposes: in rivers draining collection pools in order to control the level of water in the upper pools;

(1) Finally, for use on the crest of fixed dams in order to control the water level in the upper pool.

After examining the conventional types already cited above, it must be concluded that in all of them the panel is plane and that in none of them were steps taken for the introduction of a novel configuration more in line with the technical progress of hydrodynamics. Not even in the more modern types cited by Dehnert and Press is there such an objective to be found. Similarly, the question of the solids discharge seems only to have been thought of in the belly-shape dams. All of this tends to point out the large technological progress embodied in the idea of condensing in a single part, all the elements required for the operation of the dam. No machines or external power are necessary for moving the dam and thus the original objective of Chanoine is attained without the drawbacks of the latters pioneer darn.

Description of dam Figure 1 is a transverse section through the dam, taken on a plane indicated by line 1-1 on Figure 2 looking in the direction of the arrows. Figure 2 is an elevation view of the dam as seen from the rear, or downstream side. Figure 3 is a schematic analysis of hydraulic forces which are exerted upon the panel.

It will be seen that the dam comprises the following elements illustrated in the drawings, each of which has its definite function.

Referring to Figures 1 and 2, 1 indicates the rudder or bafiles made of structural steel aflixed to the uppermost metallic portion of the dam, and which by the water pressure exerted against them cause the dam to rotate in a counterclockwise direction and thereby to open to permit passage of water. The dam crest, which is also made of metal, is indicated at 2 and, as shown, is concave in form toward the center of the dam and axis 7. The sub-crests 3, also metal structures, and concave toward the center of the dam, project below the level of crests 2. It will be noted by reference to Figure 2 that crests 2 are located between the several bafiles 1, while sub-crests 3 are located subjacent to the baffles. The curved upstream surface of the dam, also made of metal, is shown at 4 and serves as a mounting for the baffles 1. Mounted opposite plate 4 is downstream plate 4 which is secured to upstream plate 4- and the general dam structure by means of the several bracing members 6. It will be noted that bracing members 6 project through downstream plate 4 to secure upstream plate 4. Formed between the two plates 4 and 4' is a trough or channel 5 (subdivided into sections by members 6) for the flow of water within the dam itself when the dam is in the open position, as will be described hereinafter. The dam in its entirety is supported on axles 7 which extend outwardly into bearings or pillow blocks 7'.

Axles 7 are firmly secured to concrete block 8, which acts as a counterbalance in the operation of the dam to return the panel to the closed position. The bearings 7' are secured to the concrete foundation shown in the drawings. Near the bottommost edge of concrete block 8, there is secured by means of the metallic attachment members W a cylindrically-shaped metal counterweight 9. Both block 8 and weight 9 are centered below axis 7. At is shown a grate or screen which is secured to the upstream face of plate 4 and extends down, over, and substantially covering the open upstream end of channel 5, so as to prevent solid objects from blocking or otherwise interfering with the flow of water therethrough. A

reversely-bent endwise portion 21 of grate 20 abuts against a stop 23 secured to the concrete foundation when the dam is in a closed position.

On the sill of the dam there is provided continuous or discontinuous stops 10 which have a concrete backing guarded by a gasket or facing of resilient material 24. The metallic counterweight 9, when the dam is in the closed position, bears against gasket 24. As suggested, the stops 10 may be either continuous, extending the entire width of the dam, or may be intermittent, providing intervening spaces between segments as shown in Figure 2.

Below the dam there may be provided a certain space 11, to permit continuity of solids discharge, or discharge of water for that matter, through the dam where necessary or expedient. This space 11 is provided by so mounting the darn as to allow a small clearance so that water may pass through the space shown and between the intermittently arranged and spaced stops 10. It will be noted that the approach to the dam is sloped at 12 to provide the proper access and clearance space 11, and a contraction zone for the water approaching the dam. The lower surface of the liquid vein or conduit feeding water to the dam is indicated at 13 and has a downward slope constituting part of an expansion Zone for the stream of water. Pillars for supporting the grids intended for removal of large solid objects is shown at 14. At 16 there is shown a stop mechanism for limiting the maximum rotation of the dam in the open position.

Operation of the dam- All the elements mentioned above have been determined by means of experiments carried out until the final type shown in Figures 1 and 2 was developed, said type constituting the novel movable panel dam which is the subject matter of the present application.

According to the classical ideas on the subject, the theory controlling the operation of such dams is based on the static effect of the pressures exerted on the panels. Whenever the resultant pressures act above the rotational axis of the panel, the latter rotates and the dam starts to operate. However, this classical theory does not take into account the dynamic action exerted on the panel.

The laboratory experiments carried out for the choice of the final panel profile proved that the dynamic action has a very great influence on the operation of the dam. Thus, the dam operates truly subject to static and dynamic forces, in a manner quite different from that supposed by the classical theories. Dynamic effects have their influence, together with the static forces, in the collapsing of the dam and in the return of same to its raised position.

The applicant will now describe what has really occurred in the laboratory test canal. In the discharge of a mass of water, the automatic movable dam may be in one of the three operating conditions: (a) raised dam; (b) transition phase; (c) closed dam.

For discharges up to a certain volume, the dam will remain closed and the continuity of flow across the structure will take place over a weir-acting part of the dam or through a part of same, 11, acting as a lower gate. In this condition of operation, the forces due to static and dynamic pressures derived from the flow will produce a rotating torque or couple with regard to bearing 7, said couple being smaller in value than the stabilizing couple due chiefly to counterweights 8 and 9.

The downstream darn surface is subject to atmospheric pressure because bafiles 1, placed on the dam crest, break up the overflowing sheet of water, allowingair to penetrate along crest 3 into the space between the dam and the overflowing sheet of water.

As the discharge begins to rise and to reach a certain value, the dam begins to open slightly, and the following phenomena may be observed in the order cited:

, (a) A pocket of air is formed at a point immediately d wn eam f om t am. as the disch r e start to grow:

(b) Said pocket then disappears, simultaneously with a somewhat quicker opening of the panels, thus'reducing the upstream water level because of greater flowcapacity;

(c) A pocket of air is then formed at .a point immediately downstream from the baflles; as the discharge increases said air pocket also disappears completely and at the same time the dam panel opens somewhat more, thereby rendering the flow easier. 7

During this transition phase, it is observed that the panel oscillates a little, although it does not have sharp movements. This is a favorable feature, in view-of the lubrication required by the supporting bearings 7.

At very high discharges the movable dam panels will be completely under water. No air pockets are formed in this operating phase and it is seen that the-structure slopes gradually as the discharge increases.

The fact that the panels do not open all ,of a sudden provides the darn with certain upstream water level control features at least up .to a discharge corresponding to a completely overflooded dam. That is, where the frictional resistance of the panel form becomes appreciable, the loss of head begins to increase withthe discharge to a point where the upstream water level rises.

For all dam positions and therefore for all-water discharge rates, the movable panel remains perfectly-stable. If, because of some external cause, the panel should be moved away from its dynamically compensated position, it will be immediately returned to the same position after some damped vibrations. This damping effect on the vibrations, which is so important for the operation .of the structure, may be explained as follows:

As the discharge increases, so does the dynamic action of the sheet of water overflowing the dam crest, ;this action being exerted on the baflles 1 and thus promoting opening of the dam. At the same time the liquid mass overflowing the darn tends to expel the air accumulated along .the downstream surface of the structure and this, together with the dynamic action of the flow of .water through trough will operate dynamically on the under faces :2 and 3 of the curved metal plate constituting the dam crest, thus damping the collapsing movement of the movable panels.

The greater the discharge of the watercourse, the flatter the slope of the dam and greater the action of the concrete shields provided on the structure slab, which deflect upwards the liquid mass flowing along the lower part of the dam. The said upwardly deflected liquid mass will then act upon the downstream dam face, opposing the dynamic thrust directly exerted by the flow of water upon the upstream face of the opened dam.

The dynamic actions exerted upon the opened panels are always opposed and balanced, this being the reason why the panels always tend to be in equilibrium in some sloping position of the dam. Therefore, for each and every instantaneous discharge of the watercourse, these dynamic actions correspond to a definite angular position of the movable panels. The greater the discharge, the flatter the inclination of the structure. The greater the discharge, the greater will be the restraining action on the movable panels, and this proves that said dynamic actions do constitute indeed the damping and retaining means for the movable panels. Therein lies the difference in regard to conventional systems.

Figure 3 illustrates diagrammatically said dynamic actions which are as follows:

F dynamic action of flow over the dam, exerted upon the baflies placed above the dam crest;

F dynamic action of the liquid flow from the trough and of water flowing under the panel, exerted upon the curved part provided in the crest of said panel;

F direct action of flow upon the upstream face of the panel;

F --dynamic action of said flow upon the lower downstream face of the opened panel, due to deflection of flow under the dam caused by thesrnall concrete stops 10 placed above :the bottom slab or sill.

Dynamic actions F F and F F are always opposed andbalanced, and thus the panels always tend to reach an equilibrium at a position defining the inclination :of the dam.

Thus, as already mentioned herein, for each :and every instantaneous discharge these dynamic .actions determine a certain angle at which the panel will come to rest and the greater the discharge, .the greater the inclination of the structure.

From .a diagrammatic point of view, such .a panel may be considered similar .to' a plate retained at its ends by damping or .snubbing means and subject .to ,external steady forces which would be responsible for the inclination of the plate. These are the theoretical foundations for the operation of the automatic movable .,dam herein described and claimed.

In the present application the basic ideas areembodied in Figures 1 and 2; however, the shape, the arrangement and the details of .thedifferent parts may vary as regards form and position, within the basic concept ofminimum hydraulic resistance and with .the use of shock and vibration damping means. Said hydrodynamically compensated geometrical form this is now rendered susceptible of practical .use in movable dams, with the alterations herein suggested and hereinafter claimed.

I claim:

1. An automatically adjustable dam comprising at leastone generallyplanar panel rotatable on a horizontal axis located .near the center of the panel, a stationary foundation and a conduit for conveying water to the panel, said panel having two bearings on said axis and secured to the foundation, about which said panel is adapted to rotate, one at each of the opposite endsof the dam, said panel having a substantially vertical closed position and a substantially horizontal open position, a sill in the foundation disposed adjacent the bottom edge of said panel in the closed position and adapted to co operate with said panel to obstruct the flow .of water when thedam is .in the closed position, means tending -to maintain said panel in the closed position, at. least one baflle secured to said panel, projecting out of the plane of said panel on the upstream side of said panel formed so as to be acted upon by water flowing around the panel to produce a turning torque to turn the panel toward the open position, an interior channel for the flow of water through the panel itself and formed so as to be acted upon by water flowing around and through the panel to compensate said turning'torque with a counter torque thereby to stabilize the panel and minimize vibration when water is flowing through the dam.

2. An automatically adjustable dam comprising at least one generally planar panel rotatable on a horizontal axis located near the center of the panel, a stationary foundation and a conduit for conveying water toward the panel, said panel having two bearings on said axis and secured to the foundation about which said panel is adapted to rotate, one at each of the opposite ends of the dam, said panel having a substantially vertical closed position and a substantially horizontal open position, means tending to maintain said panel in the closed position, at least one baflle secured to said panel, projecting out of the plane of said panel on the upstream side of said panel in position to be acted upon by water flowing around the panel to produce a turning torque to turn the panel toward the open position, an interior channel in the panel for the flow of water through the panel itself and formed so as to be acted upon by water flowing around and through the panel to compensate said tuming torque with a counter torque thereby to stabilize the panel and minimize vibration when water is flowing through the dam.

3. A dam according to claim 2 in which said closing means is a weight extending substantially lengthwise of the panel forming an integral part of said panel and having a center of gravity below said axis.

4. A dam according to claim 3 in which said Weight comprises a concrete member and a metal member, each of which has a center of gravity below said axis, the metal member being. adjacent the bottom edge of said panel and adjacent said seat in the closed position and extending for substantially the entire length of said bottom edge.

5. A dam according to claim 2 in which stop mechanisms are provided adjacent the bearings and secured to the foundation for contacting the panel and thereby limiting its rotation toward the open position.

6. An automatically adjustable dam comprising at least one generally planar panel rotatable on a horizontal axis located near the center of the panel, said panel having an upstream plate exposed directly to the water flowing toward the dam, a stationary foundation and a conduit for conveying water toward the panel, said panel having tWo bearings on said axis and secured to the foundation about which said panel is adapted to rotate, one at each of the opposite ends of the dam, said panel having a substantially vertical closed position and a substantially horizontal open position, means tending to maintain said panel in the closed position, at least one baflle secured to said upstream plate projecting out of the plane of said panel on the upstream side of said panel in position to be acted upon by water flowing around the panel to produce a turning torque to turn the panel toward the open position, a downstream plate backwardly spaced from and rotatably movable with said upstream plate to provide therebetween a channel through which occurs a dynamic flow of water following a flow path under and contiguous to said upstream plate, said downstream plate being adapted throughout rotation from closed position of said panel to direct said dynamic flow against the downstream side of said upstream plate at a region thereof above said axis, said directed flow producing at such region a dynamic action which serves to compensate said turning torque with a dynamic counter torque thereby to positionally stabilize the panel throughout a range 8 of rotational positions thereof and to minimize vibration when water is flowing through the dam.

7. A dam according to claim 2 in which the cross section of the panel in a plane perpendicular to said axis has a geometrical form ofiering a minimum resistance to the flow of water.

8. A dam according to claim 7 in which the upper part of said panel is of sheet metal forming a channel which extends for substantially the entire length of said axis connecting the lower part of said panel with the upper part of said panel and being disposed on the upstream side of said axis and of said weight when the panel is in the closed position.

9. A dam according to claim 8 in which the upper edge of said panel curves to form a surface which is concave toward said axis and adapted to be acted upon by water flowing around and through the dam panel to supply said counter torque.

10. A dam according to claim 9 in which said upper edge is formed to produce two types of curved surfaces, one type lying directly downstream from said baffles and the other type occupying the remainder of the top edge of said panel.

11. A dam according to claim 7 having a plurality of baflles, and a plurality of partitions dividing said interior channel into a plurality of sections, so as to divide the flow of water into a plurality of streams.

References Cited in the file of this patent UNITED STATES PATENTS 46,883 Colton Mar. 21, 1865 2,598,389 Jermar May 27, 1952 FOREIGN PATENTS 4,107 Sweden Feb. 15, 1893 517,315 Germany of 1931 557,592 Germany of 1932 696,614 Germany Sept. 25, 1940 718,942 Germany of 1942 728,714 Germany Dec. 2, 1942 758,796 Germany of 1952

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