Deflector system for hydraulic dam

Abstract

System for a hydraulic dam (B), comprising: a deflector (1) configured to divert a water flow exiting a spillway (V) of the dam (B), relative to a principal flow direction of the water exiting the spillway (V); a catch basin (3) downstream of the deflector (1) for recovering objects carried by the water flow; and a pit (2) downstream of the deflector (1) and upstream of the catch basin (3), the pit (2) being adapted to dissipate at least some of the 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). Figure for the abstract: Fig. 1

Description

Title of the invention: Deflector system for hydraulic dam FIELD OF INVENTION

[0001] The present invention relates to a system for a hydraulic dam. STATE OF THE ART

[0002] In order to carry out regulatory inspections on the normally submerged parts of a hydraulic dam, or to perform maintenance work, it is necessary to drain the reservoir of such a dam. This draining is accompanied by environmental measures, including the recovery of all the fish present in the reservoir. Some can be recovered by catching them from the reservoir upstream of the dam, but the majority of the fish will be recovered downstream of the dam, once the water volume has passed through the dam's discharge valves.

[0003] To recover fish downstream of a dam during a draining operation, it has been proposed to use a recovery grid. Operators walk along the grid to collect the fish.

[0004] However, a jet of water coming out of a drain valve V of a dam is dangerous (its (speed can reach 25 meters per second). This is why the grid is placed at a sufficient distance from the dam so that operators can work on the grid plan under satisfactory safety conditions.

[0005] However, some sites do not allow for the placement of a recovery grid sufficiently far 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 power lines.

[0006] On these sites, the installation of a recovery grid, access points, and the removal of containers several tens of meters from the structure thus becomes a problem. Description of the invention

[0007] One object of the invention is to overcome the above-mentioned problem.

[0008] This goal is achieved by a system for a hydraulic dam, the system comprising: a deflector configured to divert a water flow out of a dam outlet valve, relative to a main flow direction of the water flow out of the outlet valve; a collector downstream of the deflector to recover 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 some of the kinetic energy of the water flow after the water flow has been diverted by the deflector and before the water flow reaches the recovery grid.

[0009] This system, which is the first subject of this disclosure, may include the following features, taken alone or combined with each other whenever technically possible.

[0010] Optionally, the deflection of the water flow by the deflector includes a downward vertical deflection.

[0011] Optionally, the vertical deviation is at least 90 degrees with respect to the main flow direction.

[0012] Optionally, the vertical deviation is at most 180 degrees with respect to the main flow direction.

[0013] Optionally, the deflection of the water flow by the deflector includes a horizontal deflection.

[0014] Optionally, the horizontal deviation is at most 90 degrees with respect to the main flow direction.

[0015] Optionally, the pit is arranged below the deflector.

[0016] Optionally, the deflector is divergent.

[0017] 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.

[0018] Optionally, the system includes a settling tank downstream of the dissipation tank, to recover sediments carried by the water flow.

[0019] A second object of this 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 discharge valve of a hydraulic dam; and opening the discharge valve. DESCRIPTION OF THE FIGURES

[0020] Other features, objectives and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0021] Fig. 1 is a vertical cross-sectional view of a system according to a first embodiment.

[0022] Figure 2 includes front views of three embodiment variants of a deflector.

[0023] The [Fig.3] is a horizontal cross-sectional view of a system according to a second embodiment.

[0024] Figure 4 is a horizontal cross-sectional view of a system according to a third mode of realization.

[0025] The [Fig.5] is a vertical cross-sectional view of a system according to a third embodiment.

[0026] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0027] A hydraulic dam B is shown in [Fig.1].

[0028] The hydraulic dam B, known in itself and more simply referred to as dam B hereafter, separates an area R upstream of the dam (usually known as the reservoir) and an area A downstream of the dam. In this text, the terms "upstream" and "downstream" implicitly refer to the direction of water flow.

[0029] The main function of dam B is to retain water in reservoir R.

[0030] The dam B includes at least one drain valve V capable of being opened or closed.

[0031] The drain valve V delimits a passage for a flow of water, this passage having an inlet orifice opening into the reservoir and an outlet orifice opening into the area downstream of the dam.

[0032] 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 area A downstream of the dam B via this passage.

[0033] The drain valve V imposes a flow direction on such a water flow. In what follows, we will focus in particular on the principal flow direction of the water flow when this flow is ejected from the drain valve V through its outlet orifice. In the embodiment of [Fig. 1], this flow direction is horizontal, but it could be different in other embodiments. To determine the principal 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.

[0034] When the drain valve V is closed, a shutting 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 [Fig.1], the shutting element is shown as a vertical wall that moves in translation, but it is understood that this representation is only schematic, and that other forms of shutting element are conceivable.

[0035] Figure [1] also shows a system according to a first embodiment, to facilitate the recovery of objects such as fish during a draining of dam B.

[0036] The system comprises a deflector 1 at the outlet of the drain valve V, a pit 2 downstream of the deflector 1, and a recovery unit 3 downstream of the pit. It is therefore understood that a flow of water exiting the drain valve will successively pass through the deflector 1, then through the pit 2, before reaching the recovery unit 3.

[0037] The deflector 1 is configured to deflect a flow of water exiting the drain valve V, from the main flow direction of the water exiting the drain valve V. By deflection, 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.

[0038] In the first embodiment shown in [Fig. 1], the deflection caused by the deflector 1 includes a downward vertical deflection. In other words, the deflector 1 forces the water flow into a downward turn that the water flow would not naturally take in the absence of the deflector 1.

[0039] The vertical deflection provided by the deflector 1 is greater than 90 degrees but less than 180°.

[0040] The deflector 1 comprises a deflecting plate 10 having an internal guiding surface 12 for directing the water flow. The internal guiding surface 12 preferably has a curved profile, which prevents the water flow along this surface 12 from separating.

[0041] The internal guiding surface 12 of the deflector 1 terminates with a free exit edge 14.

[0042] In this first embodiment, the outlet edge 14 is arranged lower than the drain valve V.

[0043] The internal guiding surface may have a width between 1 meter and 6 meters and / or a height between 1 meter and 6 meters.

[0044] 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 water flow velocity vector during the deflection. The component of the water flow velocity vector exiting the drain valve V is oriented in a first direction (to the left), while the horizontal component of the water flow velocity vector exiting the deflector 1, i.e. at its lower free edge, is oriented in a second direction opposite to the first (to the right).

[0045] The vertical deflection provided by the deflector 1 is also at most 180 degrees.

[0046] In the embodiment of [Fig. 1] this vertical deflection 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 the level of its lower free edge 14.

[0047] The deflector 1 further comprises two lateral walls extending transversely to the deflecting sheet, and being mutually opposite.

[0048] Figure 2 shows three variants of the deflector 1, viewed from the front. Preferably, the deflector 1 is divergent, as can be seen in the variants of the middle and right of [Fig. 2]. This divergence is achieved in particular by making the lateral walls of deflector 1 flare outwards from upstream to downstream, that is, as the water flow along the deflector plate approaches the lower free edge 14. The divergent nature of deflector 1 is advantageous because it reduces the velocity of the water flow. Thanks to this reduction in velocity, the water flow has less energy and is less likely to erode pit 2 and the dam toe. In the variant shown on the left of [Fig. 2], deflector 1 is not divergent because the two lateral walls of deflector 1 are parallel.

[0049] The deflector 1 can be fitted onto a rectangular opening. An alternative is to fit it onto a circular conduit. In this case, the deflector 1 resembles an elbow equipped with axial and radial load-bearing devices.

[0050] The pit 2 is arranged below the deflector 1. In particular, the free edge overhangs the pit.

[0051] The pit 2 is adapted to dissipate at least part of the kinetic energy of the water flow after the water flow has been deflected by the deflector 1 and before the water flow reaches the recuperator 3.

[0052] Pit 2 is delimited by a rear wall, which is closest to dam 2 (or even forms part of dam 2), two mutually facing side walls (not visible on [Fig.1]), and a bottom wall.

[0053] The pit 2 can also be delimited by a front wall opposite the rear wall, the front wall being closer to the collector 3 than is the rear wall. The front wall is, however, of a suitable height so as not to impede the flow from reaching the collector 3.

[0054] It will be noted in particular that the deviation of more than 90 degrees imposed by the deflector on the water flow exiting the drain valve V causes a distance between the area where the water flow reaches pit 2 and the collector 3. In particular the water flow is likely to run along the rear wall which delimits pit 2, and which is closest to the dam 2.

[0055] The function of the collector 3 is to collect objects carried by the water flow, such as fish.

[0056] Preferably, the collector 3 includes a recovery grid arranged so that the objects to be recovered remain on the grid while the water flow passes through the grid. A grid has the advantage of being more robust than a recovery net, and allows for the evolution of operators to retrieve the carried objects.

[0057] For example, the retrieval grid comprises a plurality of parallel bars spaced apart by a spacing that is a function of the size of the objects to be retrieved. This spacing is, for example, equal to 25 millimeters.

[0058] The recovery grid is arranged so as to facilitate the arrival of the water flow from pit 2 above the recovery grid. The grid may be slightly inclined with respect to the horizontal.

[0059] The system described above is functional once the deflector 1 is mounted downstream of the drain valve V, the pit 2 is formed, and the recovery unit 3 is installed, along with access to this recovery unit for operators. The drain valve V is opened, for example, to a height equivalent to the design flow rate of the deflector 1. The water flowing from the valve enters the deflector 1 and exits after making a turn of approximately 180°, before falling back into the pit. The flow exits this pit as a free stream and passes through the recovery grid, which retains solid objects. Operators walk along the grid, equipped with tools to collect the retained objects, and store them in containers placed, for example, along the side of the grid. Once full, these containers can then be lifted by crane and removed.

[0060] It should be noted in particular that the recovery of the fish initially present in reservoir R is intended to preserve the fauna or flora downstream of dam B. A sudden arrival of a very large quantity of fish during a draining of the dam would in fact risk disturbing this fauna or flora, and harming biodiversity.

[0061] 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.

[0062] Similar to the constraints imposed by fish populations, sediment constraints exist for certain structures. During draining, the project owner must avoid degrading the downstream environment by allowing a significant volume of sediment to flow from upstream to downstream, which could harm biodiversity. Settling tank 5 allows for the recovery of most of the sediment present in the water flow. The sediment settles by gravity to the bottom of the tanks when water velocities are low. The sediment is discharged when the outflow is zero.

[0063] The settling tank 5 is also upstream of the receiver 3. In other words, the settling tank 5 is located between the dissipation tank 2 and the receiver 3.

[0064] 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 lower free edge at the vertical. The deflector 1 causes a decrease in the horizontal component of the velocity vector of the water flow, but this decrease stops essentially at zero, whereas this component changed direction in the first embodiment discussed above.

[0065] The deflector 1 is arranged with respect to the collector 3 so that the water flow 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.

[0066] Figure 5 shows a fourth embodiment of the system described above, in which the deflector 1 diverts the water flow exiting the drain valve V horizontally. In other words, the water flow "turns" within the deflector 1, without necessarily changing its altitude. In this third embodiment, the deflector plate can extend vertically relative to the ground. This arrangement allows for a reduction in the horizontal component of the water flow velocity vector in the direction of water flow, similar to the second embodiment.

[0067] The horizontal deviation shown in [Fig.5] is 90 degrees, but could be less.

[0068] In practice, the dam B may include several drainage valves V. It is then possible to place deflectors 1 conforming to any of the embodiments described above, at the outlet of several respective drainage valves V of the dam B, or even all the drainage valves V of the 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 (diverging or not) shown in [Fig.2] are applicable to all the system embodiments discussed previously, and not only to the first embodiment.

Claims

Demands

1. System for a hydraulic dam (B), the system comprising: • a diverging deflector (1) configured to deflect a water flow out of a drain valve (V) of the dam (B), relative to a principal flow direction of the water flow out of the drain valve (V), • a recuperator (3) downstream of the deflector (1) for recovering objects carried by the water flow, • a dissipation pit (2) downstream of the deflector (1) and upstream of the recuperator (3), the dissipation pit (2) being adapted to dissipate at least some of the kinetic energy of the water flow after the water flow has been deflected by the deflector (1) and before the water flow reaches the recovery grid (3).

2. System according to the preceding claim, wherein the deflection of the water flow by the deflector (1) includes a downward vertical deflection.

3. System according to the preceding claim, wherein the vertical deviation is at least 90 degrees with respect to the principal flow direction.

4. System according to any one of claims 2 and 3, wherein the vertical deviation is at most 180 degrees with respect to the principal flow direction.

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

6. System according to the preceding claim, wherein the horizontal deviation is at most 90 degrees with respect to the principal flow direction.

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

8. A system according to any one of the preceding claims, wherein the retrieval device (3) comprises a grid arranged so that the objects to be retrieved remain on the grid while the water flow 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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