Patent Application
20050111916
The invention generally belongs to the domain of civil engineering, namely the field of river regulations, or even more to the devices for the dissipation and/or loss of excess kinetic energy.
The present invention is based on the problem, how to achieve, at each required spillway of the hydro power plant weir or similar hydraulic structure, even at relatively small approach energy heads and relatively high discharges, i.e. at very low Froude numbers, and by negligible decrease of interior transversal cross-section of the spillway by the construction of new hydraulic structures or even only on the basis of an economically acceptable modification of an existing structure, the effective dissipation and/or loss of excess kinetic energy and thus prevent the bottom and banks of each required river channel downstream from the spillway against extensive erosion.
Hydraulic structures as hydro power plant weirs and similar structures as usually consist of a certain number of spillways, where each one spillway usually is positioned between vertical or inclined side walls, by which it is bounded transversely considering the water flow direction. In longitudinal direction the spillway is spread all the way from the upstream water surface i.e. the area above the weir and/or above the gate, to the area of the downstream water surface, i.e. behind the end of so-called stilling basin. Due to each time available difference between the upstream and downstream water surface, a portion of the potential approach energy in a spillway is transformed into kinetic energy that one strongly influences on the flow conditions, types of flow profiles and erosion, respectively. For this reason at the hydraulic structures, there always is a need for the loss of the excess kinetic energy, therefore must be dissipated, because the excess energy would cause extensive erosion effects of the downstream river channel bottom and banks, not only to/for immediately behind from the stilling basin, but also on a considerable downstream distance, as well. Loss of the excess kinetic energy, say dissipation, is generated in a hydraulic jump located in the consolidated structure resistant against erosion, namely in a stilling basin.
Those skilled in the art are aware, that by means of appropriate design of the longitudinal section of a spillway, it is possible to establish the hydraulic conditions, that are, in the predicted ranges of the energy heads and flows, preventing or at least minimizing the undesirable effects of erosion due to the kinetic energy portion. Therefore it is important, for instance, the design of the weir that is described for example in EP 0 477 745. The design of stilling basin, which is adequately formed, treated or concreted terminal hydraulic structure, located between the spillway chute of the barrage and above the tailwater, that is available behind/below the hydraulic structure, is also of the key importance. It should be considered, that the longitudinal profile of the spillway is always calculated and built for the defined operating conditions which may vary significantly in practice. The problems arise at an enormous increases of flow discharge, as at so changed conditions (at increased of flow discharge and at increased approach energy head, as well) the portion of the non-dissipated kinetic energy significantly increases and threatens the tailwater river channel behind the hydraulic structure.
To assure the most effective dissipation, i.e. loss of the excess or undesired portion of the kinetic energy of the water flow, a series of solutions are already known. Therefore the author of the invention is familiar with the solution where a concrete blocks, weighting several tones were placed behind the stilling basin area expecting the increased dissipating effect, but in fact by increased water flow due to intensive rain fall these blocks swept away from behind the stilling basin area and carried it out downstream from the hydraulic structure.
It is furthermore known from the U.S. Ser. No. 09/072,836 (WO 99/57377), that the spillway chute above the mentioned stilling basin may be equipped with the series of steps. Such arrangement may be effective to a certain degree at the adequately high difference between upstream and downstream water surface and/or at the adequately high stilling basin depths at the foot of spillway. When the differences in energy heads are present, the other solutions improving the dissipation and/or loss of the excess kinetic energy are available, as well. It is known that the so-called baffle blocks may be located in the stilling basin, namely a kind of vertical or inclined consoles fixed on the stilling basin bottom, or construction compose with parallel bars so-called racks, where the water flows down and/or withdrawal through the openings. The last one is among the others described in U.S. Pat. No. 5,032,038. The water flow over such structures, with which in general may be arrange even at already existing hydraulic structures and that are being up to the certain arrangement supplement in this way, may actually cause certain dissipation, but only in the case of the adequately discharge at the adequately head, what means at large enough Froude numbers. The theoretical calculations as well as the results acquired through practice are showing, that at the small heads or under the lower limit value of the Froude number such solutions have no effect and therefore they are meaningless. Such problematic is described also in the technical literature and in scientific publications, as e.g.:
By water flows with the relatively high discharge and small head (small altitude difference), which are characterized by low Froude number parameter, the necessary dissipation cannot be achieved by means of the above mentioned solutions. The only way in course of achieving required dissipation would be—at least theoretically—increasing the head with the lowering of the stilling basin bottom in artificial manner.
Such a solution is feasible only by the designing of new hydraulic structures. Modification of the existing structures using this approach, requires breaking of the huge quantities of concrete in the stilling basin area, lowering the bottom and repeated concreting, which is not economically feasible and is therefore irrational. It should be mentioned, that even the designing of the new structure with the adequately lowered stilling basin bottom tremendous increases the investment costs of the structure. Such a solution actually demands the preparation of the basement on the significantly larger depths as usually, and at the same time this solution demands considerably higher, more solid and more stable structure of construction.
A further attempt in course of achieving efficient dissipation is described in RU 479848. However, the described structure belongs to the domain of small canal structures, or even more to the domain of the devices for the dissipation the excess energy of storm runoff flows or irrigation or drainage water inflow in the reservoir lakes or the like, where in lakes always enough and to spare tailwater depth, at the chute outlet, exist.
Therein, the canal structure is foreseen, made of several different structural parts which together make up the complete structure. The structure consists of the flume inlet, the inclined chute i.e. drop section, the stilling pool, and the outlet section. The chute is an open rectangular inclined channel. It is rectangular in shape of constant width, the same as the inlet and the pool section.
The necessities in operation functions of the mentioned chute are not only to convey water from a higher to a lower elevation and dissipate excess energy resulting from this drop, but also to prevent reverse surface currents downstream from the outlet at tailwater section, what is the main addition attention i.e. the point of view for mentioned structure in operation. For satisfaction all this necessities in operation, the inclined rectangular chute is moreover equipped with several continuous transverse deflection steps along the inclined bottom, which were as evident from the said document already known before, and in addition also with several continuous transverse beams, which are positioned inside the inclined rectangular chute between the side walls at the fixed distance from the inclined bottom.
The transverse deflection steps together in pairs with transverse beams are generally an impact type energy dissipator. The transverse beams of inclined chute also stills the water after it has reached the lower water elevation and prevent reverse surface currents irrespective of downstream water level in accumulation lake between minimum and maximum. This last happens when the streams of water flow in submerged portion of the inclined section are thrown upwards by the bottom deflection steps, to the neighbouring transversal beams and so deflected streams hits the beams and are then returned by this obstacles back in the main flow. In this sequence of changing the direction, the strong turbulence is occur in water flow in the section between the bottom and under the beams of the inclined part of channel and essentially energy is dissipated simultaneously in the resulting turbulence. By using such transversal beams, the effect of reversible streaming should be essentially reduced regardless to certain variations of the level of the downstream lake and to certain variations of the water discharge in the chute.
At smaller tailwater depth and at smaller flow—discharge thru the chute, in the stilling pool, closed with side vertical and front inclined wall, installed at the lower end of rectangular inclined chute to obtain the required loss of energy between the lower end of the inclined channel and downstream water level.
At larger discharge, e.g. a full flow through the chute, certain amount of water flow passes over the beams. In this case the flow under and between the transversal beams joins the reservoir partly above its level. Because the main amount of excess energy is dissipate in water flow in the section between the bottom and under the beams of the inclined channel, also in this cases formation of reverse currents are prevented.
The use of the such mentioned constructions arrangement, may in fact result in smaller and more economical structure, which requires less riprap or gravel erosion protection at the neighbor earth banks section of reservoir lake.
However, an important disadvantage of the described construction has to be taken into account. The transversal beams unavoidable reduce the effective water cross profile and in fact more-less reduce discharge outflow capacity from the inclined rectangular channel. This is especially problematic, when appreciable amount of debris, trash, bushes, part of trees or tumbleweeds is accompanid to the flow, since these parts may become lodged between the beams and in inclined section under the beams, which leads to essential restricting the flow. In addition, removal of this material is sometimes very difficult.
Consequently, such chute is conditionally useful as a small hydraulic object, so that the size of such structure and its discharge capacity is essentially, in each case several times e.g. ten times or even more, smaller than by the spillway with improved dissipation efficiency in accordance with the present invention.
Accordingly, the present invention relates to a spillway of a hydro power plant weir or similar hydraulic structure, consisting the consolidated stilling basin, which is located—when observed in the flow-direction—directly behind the spillway chute and when desired also concluded with the end sill and on the sides constrained with at least essentially vertical or inclined side walls. When desired, in the area of such spillway, a suitable gate or similar closing structure is proposed. The above mentioned stilling basin with the spillway chute and if/when required with the end sill together with the mentioned side walls represents the uniform, compact structure for the control of the hydraulic forces and other phenomena, between the reservoir area of each river channel, that takes place above/before the mentioned spillway and the downstream river channel with the corresponding banks behind/below the dissipation area.
According to the invention, there is, in the area of at least one of the side-walls of each required spillway, proposed at least one essentially in the flow direction oriented and into the interior cross-section of the spillway from sidely protruding dissipation beam. Preferably, in the area of each side wall of each required spillway, at least one, especially preferable just always at least one, at least essentially in the flow direction oriented and into the interior cross-section of the spillway sidely protruding dissipation beam is available.
According to the invention there are considered as suitable foresee at least two straight or once or even more times broken formed dissipation beams, which are positioned along the area from the spillway chute either horizontally in the flow direction or inclined raising or descending, considering the horizontal section all the way to the lower end of the stilling basin or even to the end of the end sill. This dissipation beams are disposed at least essentially in the flow direction and either parallel between each other or inclined between each other so that they are converge or diverge each other.
Transverse profile of each required beam may be either square profile or at least essentially regular circular profile or also upright or flattened rectangular profile.
Furthermore, each dissipation beam may be shaped as at least rectangular or square cut-off profile in its transversal direction, where the lower and the upper surface of the beam is at least essentially hyperbolically hollowed, while side surface of the beam is flat and smooth and at least essentially vertical.
Furthermore, each dissipation beam may be shaped as at least trapezoidal profile in its transversal direction, where the lower and the upper beam surfaces are flat and smooth and horizontal as well, while side beam surface is flat and smooth, but at the same time inclined outwards and downwards.
Furthermore, each dissipation beam maybe shaped in its transversal direction, where the lower and the upper surfaces are at least hyperbolically widened in the direction against the corresponding side-wall, while the side-surface of the beam is flat, smooth and completely vertical.
Furthermore, each dissipation beam may be shaped as at least trapezoidal profile in its transversal direction, where the lower and the upper beam surfaces are flat and smooth and horizontal as well, while side beam surface is flat and smooth, but at the same time inclined downwards and inwards.
Furthermore, each dissipation beam may be shaped as an rectangular upright profile in its transversal direction, where the lower and the upper surfaces are flat and smooth and parallel, otherwise the flat and vertical side-surface is shaped with the rectangular, longitudinally oriented groove.
Furthermore each dissipation beam may be shaped as an trapezoidal profile in its transversal direction, where the lower and the upper beam surfaces are flat and smooth, but inclined so that they are converge between each other in the direction of the corresponding wall, while the flat and smooth side-surface is at least essentially vertical.
Furthermore, each dissipation beam may be shaped as at least rectangular or square cut-off profile in its transversal profile, where the lower and the upper surface of the beam is at least essentially hyperbolically hollowed, similarly the beam side surface is hollowed, as well.
Furthermore, each dissipation beam may be shaped as at least T-profile in its transversal direction, where the lower and the upper beam surfaces are gradually hollowed in the areas directly next to the wall, while the side surface of the beam is flat, smooth and vertical.
Furthermore, each dissipation beam may be shaped as at least trapezoidal profile in its transversal direction, where the upper surface and the side surfaces of beam are flat and smooth and normal to each other, while the lower surface of beam is flat and smooth, but inclined inwards against the corresponding side wall and upwards.
Furthermore, each dissipation beam may be shaped as at least rectangular upright profile in its transversal direction, where the upper and lower surface are flat and smooth and parallel to each other, while the side flat and smooth surface is equipped with the centrally positioned rectangular, longitudinal groove, inside which another centrally positioned rectangular and longitudinal groove, is available.
Furthermore, each dissipation beam may be shaped as at least trapezoidal profile in its transversal direction, where the lower surface and the side surfaces of beam are flat and smooth and normal between each other, while the upper surface of the beam is in principle flat and smooth but inclined inwards against the side wall and upright.
Furthermore, each dissipation beam may be shaped as at least rhomboidal profile in its transversal direction, where the lower and the upper surfaces are in principle flat and smooth but inclined in the direction downwards against the corresponding side wall, while the side surface is flat, smooth and vertical.
Furthermore, each dissipation beam may be shaped as at least E-profile in its transversal direction, what means rectangular upright profile with the straight, smooth, horizontal and therefore parallel surfaces, with the vertical side surface, that is realized with two parallel along the beam positioned at least required rectangular grooves.
Furthermore, each dissipation beam may be shaped as at least H-profile in its transversal direction, what means rectangular upright profile with horizontal and therefore parallel surfaces, of which one is equipped whit one at least square-profiled groove, and with the flat, smooth and vertical side surface.
Furthermore, each dissipation beam may be shaped as an modified H-profile in its transversal direction, that is an upright rectangular profile with the horizontal and between each other in principle parallel surfaces, where the upper surface is gradually hollowed in the direction against the corresponding side wall, the lower surface is equipped with the rectangular groove in longitudinal direction, while the side-surface is at least essentially flat, smooth and vertical.
Furthermore, each dissipation beam maybe shaped in its transversal direction, where the upper and the lower surfaces are parallel as well as, while the side-surface is gradually inclined downwards and to the corresponding side wall.
Furthermore, each dissipation beam may be shaped as at least L-profile in its transversal direction, namely an upright rectangular profile with the horizontal and between each other in principle parallel upper and lower surface, where the upper surface is gradually hollowed in the direction against the corresponding side wall, the lower surface is flat and smooth, quite so is flat and smooth also the vertical side surface.
Furthermore, each dissipation beam may be shaped as an twisted U-profile in its transversal direction, that is an upright rectangular profile with the horizontal and between each other in principle parallel upper and lower surface, where the upper surface is flat, the lower surface is equipped with the rectangular groove in longitudinal direction, while the side-surface is at least essentially flat, smooth and vertical.
Furthermore, each dissipation beam may be shaped as at least represents letter X in its transversal direction, namely at least upright rectangular or square profile, where the upper surface is gradually inclined in direction downwards and inwards against the corresponding side wall, while the side surface and the lower surfaces of beam are trapezoidal hollowed, so that each of them includes a trapezoidal, longitudinally positioned groove.
Besides, according to the invention, it is proposed that the spillway includes at least one complex dissipation beam, consisting of the one next to another positioned beams, especially from one next to another positioned beams with the significantly flattened rectangular profile in its transversal direction.
Furthermore it is proposed that the spillway includes at least one dissipation beam with the profile in its transversal direction, that is either unalterable along the beam or is alterable, especially steadily, but in general may be discretely alterable.
Now the invention will be further described on the basis of embodiments as shown in the enclosed drawing, wherein
The spillway, e.g. of a hydro power plant weir or similar hydrauic structure with the improved dissipation efficiency according to the invention is presented on the
If needed or depending on the purpose of the spillway, the gate 6 or similar closing device may be positioned in the field of spillway area, that are quite schematically presented in FIGS. 1 to 10, but in a quite understandable manner for those skilled in the art. At the construction of the spillway, presented on
In order to assure the most efficient loss of the excess kinetic energy in the spillway, which means the previously mentioned dissipation, placing of the so-called dissipation beams 5′, 5″ in the area of the side walls 4′, 4″ is proposed according to the invention. In general, according to the present invention, in the area of at least one of the side walls 4′, 4″ of each required spillway at least one dissipation beam 5′, 5″ is foreseen, which extends at least essentially in the flow direction and protrudes from the side into the interior cross-section of the spillway extending dissipation beam 5′, 5″. Preferably there is at least one dissipation beam 5′, 5″ available on each of the side walls 4′, 4″ of each required spillway, but most preferably, each of the side walls 4′, 4″ is equipped by one dissipation beam 5′, 5″ of the appropriate design.
On the left side according to the
There exists a series of possibilities of the dissipation beams 5′, 5″ positioning. In general the straight or broken-shaped design of the 5′, 5″ beams may be used. Further, the 5′, 5″ beams may be positioned horizontally or inclined e.g. so that they are raising in the flow direction or descending considering the horizontal plane. Furthermore there are two, each next to its corresponding side-wall 4′, 4″, positioned dissipation beams 5′, 5″ that maybe parallel or inclined, and this may be realized so, tat they are converging each other in the flow direction or they are diverging. The designs of the in such a manner improved spillways may differentiate along the length dissipation beams 5′, 5″ as well; they may extend from the spillway 1 to the end of the stilling basin 2, or it may be considered to the upper part of end sill 3, or even over the mentioned end sill 3.
With the similar task the spillway of the hydraulic structure is shown on the
Besides number of the arrangements and the designs of the dissipation beams 5′, 5″, therefore straightness, once or more times broken formed, parallel ness or inclined ness and similar characteristics, according to the invention the dissipation beams 5′, 5″ installable to the each required corresponding side walls 4′, 4″ are distinguished by the different transversal profiles. They are schematically presented on FIGS. 13 to 36 as transversal profiles not as transversal sections. For the demands of the present invention, the fact if the dissipation beam 5′, 5″ is solid or hollow is irrelevant as for its efficiency of the achievement of the expected dissipation, the configuration of its circumference or outer circumference perimeter is of the essential importance, that in the longitudinal direction it should not be changed or in general it may vary. On FIGS. 13 to 36 some of the numerous possible transversal profiles are presented, and they may be the same along the whole dissipation beam 5′, 5″ or along the same dissipation beam 5′, 5″ may varying or changing from one (e.g. the one according to
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| P-200100302 | Nov 2001 | SI | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SI02/00026 | 11/25/2002 | WO |
