Deflector system for hydraulic dam

Abstract

The invention relates to a system for a hydraulic dam (B), comprising: a deflector (1) configured to divert a flow of water at the outlet of a drain valve (V) of the dam (B), with respect to a main direction of flow of the water flow at the outlet of the drain valve (V); a recovery device (3) downstream of the deflector (1) for recovering objects carried by the flow of water; and a pit (2) downstream of the deflector (1) and upstream of the recovery device (3), the pit (2) being suitable for at least partially dissipating a kinetic energy of the flow of water after the flow of water has been diverted by the deflector (1) and before the flow of water reaches the recovery grate (3).

Description

[0001] Deflector system for hydraulic dam

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a system for a hydraulic dam.

[0004] STATE OF THE ART

[0005] In order to carry out regulatory examinations on the normally submerged parts of a hydraulic dam, or to carry out works, it is necessary to empty the reservoir of such a dam. Emptying is accompanied by environmental measures consisting in particular of recovering all the fish present in the reservoir. Some can be recovered by fishing them from the reservoir upstream of the dam, but the majority of the fish will be recovered downstream of the dam, once the volume of water has passed through the dam's drainage valves.

[0006] To recover fish downstream from a dam during drainage, it has been proposed to use a recovery grid. Operators walk along the grid to recover the fish.

[0007] However, a jet of water coming out of a dam's discharge valve V is dangerous (its speed can reach 25 meters per second). This is why the grid is placed at a sufficiently great distance from the dam so that operators can intervene on the grid plane in satisfactory safety conditions.

[0008] However, some sites do not allow the placement of a recovery grid far enough away from the dam to allow operators to intervene safely. This may be caused by particularly steep terrain, or by the presence of equipment such as high-voltage lines.

[0009] On these sites, the installation of a recovery grid, access and the evacuation of containers several dozen meters from the structure thus becomes a problem.

[0010] STATEMENT OF THE INVENTION

[0011] An object of the invention is to overcome the above problem.

[0012] This object is achieved by a system for a hydraulic dam, the system comprising: a diverging deflector configured to deflect a water flow leaving a drain valve of the dam, relative to a main flow direction of the water flow leaving the drain valve; a collector downstream of the deflector for recovering objects carried by the water flow; and a pit downstream of the deflector and upstream of the collector, the pit being adapted to dissipate at least in part a kinetic energy of the water flow after the water flow has been deflected by the deflector and before the water flow reaches the recovery grid.

[0013] This system, which constitutes a first object of the present disclosure, may include the following characteristics, taken alone or combined with each other whenever this is technically possible.

[0014] Optionally, the water flow deflection by the deflector includes a vertical downward deflection.

[0015] Optionally, the vertical deviation is at least 90 degrees from the main flow direction.

[0016] Optionally, the vertical deviation is at most 180 degrees from the main flow direction.

[0017] Optionally, the water flow deflection by the deflector includes a horizontal deflection.

[0018] Optionally, the horizontal deviation is at most 90 degrees from the main flow direction.

[0019] Optionally, the pit is arranged below the deflector.

[0020] Optionally, the collector includes a grid arranged so that the objects to be collected remain on the grid while the water flow passes through the grid.

[0021] Optionally, the system includes a settling pit downstream of the dissipation pit, to recover the sediment carried by the water flow.

[0022] A second subject of the present disclosure is a method using the system described above. This method comprises the following steps: arranging the deflector of the system at the outlet of a drain valve of a hydraulic dam; and opening the drain valve.

[0023] DESCRIPTION OF FIGURES

[0024] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0025] Figure 1 is a vertical sectional view of a system according to a first embodiment.

[0026] Figure 2 includes front views of three alternative embodiments of a deflector. Figure 3 is a horizontal sectional view of a system according to a second embodiment.

[0027] Figure 4 is a horizontal sectional view of a system according to a third embodiment.

[0028] Figure 5 is a vertical sectional view of a system according to a third embodiment.

[0029] Throughout the figures, similar elements have identical references.

[0030] DETAILED DESCRIPTION OF THE INVENTION

[0031] Figure 1 shows a hydraulic dam B.

[0032] Hydraulic dam B, known in itself and more simply called dam B in the following, separates a zone R upstream of the dam (usually known as the reservoir) and a zone A downstream of the dam. In this text, the terms "upstream" and "downstream" implicitly refer to a direction of water circulation.

[0033] The main function of dam B is to retain water in reservoir R.

[0034] Dam B includes at least one drain valve V which can be opened or closed.

[0035] The drain valve V delimits a passage for a flow of water, this passage having an inlet opening into the reservoir and an outlet opening into the area downstream of the dam.

[0036] When the drain valve V is open while the reservoir is filled with water, a flow of water flows by gravity from the reservoir R to the zone A downstream of the dam B via this passage.

[0037] The drain valve V imposes a flow direction on such a water flow. In the following, we will focus in particular on the main flow direction of the water flow when this flow is ejected from the drain valve V through its outlet orifice. In the embodiment of Figure 1, this flow direction is horizontal, but it could be different in other embodiments. To determine the main flow direction at the outlet of the valve, a person skilled in the art could, for example, identify a bottom line of the passage delimited by the valve, and determine a tangent to this line at the outlet orifice of the valve. When the drain valve V is closed, a shutter element of the drain valve V closes the aforementioned passage, so that the drain valve V prevents water stored in the reservoir from reaching the area downstream of the dam B.In Figure 1, the shutter element is presented as a vertical wall movable in translation, but it is understood that this representation is only schematic, and that other forms of shutter element are possible.

[0038] Figure 1 also shows a system according to a first embodiment, to facilitate the recovery of objects such as fish during the emptying of dam B.

[0039] The system comprising a deflector 1 at the outlet of the drain valve V, a pit 2 downstream of the deflector 1, and a collector 3 downstream of the pit. It is therefore understood that a flow of water leaving the drain valve will successively pass through the deflector 1, then through the pit 2, before reaching the collector 3.

[0040] The deflector 1 is configured to divert a flow of water leaving the drain valve V, relative to the main flow direction of the flow of water leaving the drain valve V. By diversion, we mean that the deflector 1 imposes a change of direction on the flow of water which would not exist if the deflector 1 were absent.

[0041] In the first embodiment shown in Figure 1, the deflection made by the deflector 1 comprises a vertical downward deflection. In other words, the deflector 1 imposes a downward turn on the water flow that the water flow would not naturally take in the absence of the deflector 1.

[0042] The vertical deflection provided by deflector 1 is greater than 90 degrees but less than 180°.

[0043] The deflector 1 comprises a deflecting plate 10 having an internal guide surface 12 for guiding the deflecting water flow. The internal guide surface 12 preferably has a curved profile, which makes it possible to prevent the water flow along this surface 12 from detaching.

[0044] The internal guide surface 12 of the deflector 1 ends with a free outlet edge 14.

[0045] In this first embodiment, the outlet edge 14 is arranged lower than the drain valve V.

[0046] The internal guide surface may have a width of between 1 meter and 6 meters and / or a height of between 1 meter and 6 meters. In the first embodiment, the deflection provided by the deflector 1 is sufficient to impose a change in direction of a horizontal component of the velocity vector of the water flow during the deflection. The component of the velocity vector of the water flow leaving the drain valve V is oriented in a first direction (towards the left), while the horizontal component of the velocity vector of the water flow leaving the deflector 1, that is to say at its free lower edge, is oriented in a second direction opposite to the first direction (towards the right).

[0047] The vertical deviation provided by the deflector 1 is also at most 180 degrees.

[0048] In the embodiment of Figure 1 this vertical deviation is 180 degrees. Thus, the main flow direction at the outlet of the drain valve V being horizontal, the water flow also has a horizontal flow direction at the outlet of the deflector 1, at its lower free edge 14.

[0049] The deflector 1 further comprises two side walls extending transversely to the deflector plate, and facing each other.

[0050] Figure 2 shows three variants of the deflector 1, seen from the front. The deflector 1 is divergent, as can be seen in the variants in the middle and on the right of Figure 2. This divergence is achieved in particular by making the side walls of the deflector 1 widen from upstream to downstream, that is to say as the flow of water flowing along the deflector plate approaches the free lower edge 14. The divergent nature of the deflector 1 is advantageous, because it causes a reduction in the speed of the water flow. Thanks to this reduction in speed, the water flow has less energy, and is less likely to erode the pit 2 and the dam toe. In the variant shown on the left of Figure 2, the deflector 1 is not divergent, because the two side walls of the deflector 1 are parallel.

[0051] The deflector 1 can be fitted to a rectangular sluice. A variant is to adapt it to a circular duct. In this case, the deflector 1 is similar to an elbow equipped with axial and radial force absorption devices.

[0052] Pit 2 is arranged below deflector 1. In particular, the free edge overhangs the pit.

[0053] Pit 2 is adapted to dissipate at least part of the kinetic energy of the water flow after the water flow has been diverted by deflector 1 and before the water flow reaches collector 3. Pit 2 is delimited by a rear wall, which is closest to dam 2 (or even part of dam 2), two mutually facing side walls (not visible in Figure 1), and a bottom wall.

[0054] Pit 2 may also be delimited by a front wall opposite the rear wall, the front wall being closer to collector 3 than the rear wall. The front wall is, however, of a suitable height so as not to prevent the flow from reaching collector 3.

[0055] It should be noted in particular that the deviation of more than 90 degrees imposed by the deflector on the flow of water leaving the drain valve V causes the area where the flow of water reaches pit 2 to move away from the collector 3. In particular, the flow of water is likely to follow the rear wall which delimits pit 2, and which is closest to the dam 2.

[0056] The function of the collector 3 is to recover objects carried by the flow of water, such as fish.

[0057] Preferably, the collector 3 comprises a collection grid arranged so that the objects to be collected remain on the grid while the water flow passes through the grid. A grid has the advantage of being stronger than a collection net, and allows the evolution of operators to recover the carried objects.

[0058] For example, the recovery grid comprises a plurality of parallel bars spaced apart from each other by a spacing depending on the size of the objects to be recovered. This spacing is, for example, equal to 25 millimeters.

[0059] The recovery grid is arranged so as to encourage the flow of water from pit 2 to flow above the recovery grid. The grid can be slightly inclined relative to the horizontal.

[0060] The system described above is functional from the moment the deflector 1 is mounted downstream of the drain valve V, the pit 2 is formed, and the collector 3 is installed, as well as access to this collector for operators. The drain valve V is opened, for example by a height equivalent to the design flow rate of the deflector 1. The flow of water leaving the valve rushes into the deflector 1 and comes out after making a turn here of approximately 180°, before falling back into the pit. The flow leaves this pit in free flow and passes through the recovery grid, which retains solid bodies. Operators walk on the grid, equipped with tools to collect the retained objects, and store them in containers placed for example along the grid laterally. Once full, these containers can then be handled by crane and evacuated.

[0061] It should be noted in particular that the recovery of the fish initially present in reservoir R aims to preserve the fauna or flora downstream of dam B. A sudden arrival of a very large quantity of fish when the dam is emptied would in fact risk disturbing this fauna or flora, and harming biodiversity.

[0062] Figure 3 shows a second embodiment of the system described above, which differs from the first embodiment by the addition of a settling pit 5 downstream of the dissipation pit 3.

[0063] On the same principle as the fish constraint, sediment constraints exist on certain structures. During emptying, the project owner must not degrade the downstream environment by allowing a significant volume of sediment to pass from upstream to downstream, which could harm biodiversity. Settling pit 5 allows the recovery of most of the sediment present in the water flow. The sediments are deposited by gravity at the bottom of the pits, as soon as the water velocities are low. The sediments are evacuated when the outgoing flow is zero.

[0064] The settling pit 5 is also upstream of the collector 3. In other words, the settling pit 5 is located between the dissipation pit 2 and the collector 3.

[0065] Figure 4 shows a third embodiment of the system described above, in which the vertical deflection provided by the deflector 1 is 90 degrees. Thus, the water flow leaves the deflector 1 at the free edge below the vertical. The deflector 1 causes a decrease in the horizontal component of the velocity vector of the water flow, but this decrease stops substantially at zero, where this component changed direction in the first embodiment discussed above.

[0066] The deflector 1 is arranged relative to the collector 3 so that the flow of water necessarily reaches the pit 2 before reaching the collector 3. In particular, the free edge 14 of the deflector 1 does not overhang the collector 3, but overhangs the pit 2.

[0067] Figure 5 shows a fourth embodiment of the system described above, in which the deflector 1 deflects the water flow leaving the drain valve V horizontally. In other words, the water flow “turns” in the deflector 1, without necessarily changing altitude. In this third embodiment, the deflector plate can extend vertically relative to the ground. This arrangement makes it possible to obtain a reduction in the horizontal component of the velocity vector of the water flow in the direction of water flow, in the same way as the second embodiment.

[0068] The horizontal deflection shown in Figure 5 is 90 degrees, but could be less. In practice, dam B may comprise several drain valves V. It is then possible to place deflectors 1 conforming to any of the embodiments described above, at the outlet of several respective drain valves V of dam B, or even all the drain valves V of dam B.

[0069] Other embodiments of the system may include a deflector 1 arranged to deflect the water flow vertically and horizontally, sequentially or simultaneously.

[0070] It is further understood that the deflector configurations (divergent or not) shown in Figure 2 are applicable to all system embodiments discussed previously, and not just the first embodiment.

Claims

CLAIMS 1. System for a hydraulic dam (B), the system comprising: • a diverging deflector (1) configured to divert a flow of water leaving a drain valve (V) of the dam (B), relative to a main flow direction of the flow of water leaving the drain valve (V), • a collector (3) downstream of the deflector (1) to recover objects carried by the flow of water, • a dissipation pit (2) downstream of the deflector (1) and upstream of the collector (3), the dissipation pit (2) being adapted to dissipate at least in part a kinetic energy of the water flow after the water flow has been diverted by the deflector (1) and before the water flow reaches the recovery grid (3).

2. System according to the preceding claim, in which the deflection of the water flow by the deflector (1) comprises a vertical downward deviation.

3. System according to the preceding claim, in which the vertical deviation is at least 90 degrees relative to the main flow direction.

4. A system according to any one of claims 2 and 3, wherein the vertical deviation is at most 180 degrees from the main flow direction.

5. System according to any one of the preceding claims, wherein the deflection of the water flow by the deflector (1) comprises a horizontal deflection.

6. System according to the preceding claim, in which the horizontal deviation is at most 90 degrees relative to the main flow direction.

7. System according to any one of the preceding claims, in which the dissipation pit (2) is arranged below the deflector (1).

8. A system according to any preceding claim, wherein the collector (3) comprises a grid arranged so that the objects to be collected remain on the grid while the flow of water passes through the grid.

9. System according to any one of the preceding claims, comprising a settling pit (5) downstream of the dissipation pit (2) for recovering sediments carried by the water flow.

10. Method comprising the following steps: • arrange the deflector (1) of a system according to any one of the preceding claims at the outlet of a drain valve (V) of a hydraulic dam (B), • open the drain valve (V).

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