ES1293019U - Device for attenuating an ocean gravity wave - Google Patents

Abstract

The invention relates to a device (1) for attenuating an ocean gravity wave, the device being installed in a marine environment and comprising - at least one member (6) which is rotatably movable about an axis (A) and capable of being alternately rotated in two opposite directions of rotation by the effect of the gravity wave, attenuation means (20) capable of slowing down the rotation of the movable member (6) about the axis thereof (A), at least one porous member (16) located downstream of the movable member (6) in the general direction of propagation (D) of the gravity wave, the porous member (16) allowing seawater to be circulated through the porous member (16).

Description

description

DEVICE TO ATTENUATE AN OCEAN GRAVITY WAVE

Technical sector

The invention relates to a device for attenuating an oceanic gravity wave, installed in a marine environment.

State of the art

In fluid mechanics, a wave that travels on the free surface of a fluid subjected to gravity is called a gravity wave. In the marine environment, waves or swells are examples of gravity waves.

The coastal strip is a highly urbanized area, and has numerous facilities to meet the needs of socio-economic activities linked to urbanization. At the same time, global warming implies an amplification and multiplication of extreme weather events that erode the coastline and damage the facilities located on it, especially at the level of port areas.

Many structures are designed to provide wave protection, such as breakwaters and seawalls. The construction of such massive structures is expensive. It also requires the neutralization of affected port areas for long periods of time and changes the coastal landscape.

Documents FR 2 731 725 and GB 992 216 disclose porous box structures that allow waves to be dissipated or attenuated.

It is also known to use a device that consists of a fin that is mobile in rotation about an axis and that is at least partially submerged, the fin being moved by the movement of the waves. The kinetic energy transmitted to the fin is transformed into electrical energy by means of a generator.

Such energy conversion devices are known, in particular, from documents EP 3175111, EP 1861618, EP 2817509, US 9902467 and US 10132289.

The object of the invention is to propose a device that makes it possible to attenuate an oceanic gravity wave with greater efficiency compared to prior art devices and that can be installed in a marine environment, in particular at the level of a port area, or more generally from the coast, in a simple and inexpensive way.

Object of the invention

To this end, the invention relates to a device for attenuating an oceanic gravity wave, installed in a marine environment and comprising, - at least one element that is mobile in rotation around an axis, capable of rotating and alternately moving in two directions of opposite rotation, under the effect of said gravity wave - attenuation means capable of slowing down the rotation of the mobile element around its axis - at least one damping element located downstream of said mobile element with respect to the general direction of propagation of the gravity wave.

The attenuation means make it possible to attenuate the gravity wave, in particular the waves, in contact with the mobile element. The damping element makes it possible to further improve the attenuation downstream of the moving element. In particular, it has been found that the presence of a damping element allows, in certain cases depending in particular on the shape and dimensions of said damping element, to reduce the amplitude of the oceanic gravity wave downstream by a factor greater than 2 of the device, compared to the same device without the damping element.

The gravity wave attenuation means can be controlled by an adapted and adjustable energy extraction.

The efficiency of the mobile element is multiplied by ten thanks to the placement downstream of a damping element, by the generation of a resonant water column between these two elements. This column of water creates a very important dispersion due to its operation in resonance, which allows much more energy to be transmitted to the moving element. The more energy the mobile element receives and can recover, the better the damping of the gravity wave and, therefore, the less residual waves behind the damping element. The damping element can be in the form of at least a wall.

According to the invention, the wall is a porous wall. Such a wall can also be called a buffer zone.

The device may be designed to allow the passage of water from upstream to downstream through at least part of the device, in particular through the area of the device with the moving element and/or through the area of the device that It consists of the damping element. In particular, the device is not necessarily arranged in the form of a box consisting of an internal volume delimited by a bottom wall placed upstream or downstream of the mobile element or the damping element, and watertight side walls or that prevent the passage of water. , as is generally the case in the prior art.

Said wall can extend according to a first dimension constituting its length, according to a second dimension constituting its width and a third dimension constituting its thickness. The length of the wall is greater than or equal to the width of the wall. The thickness of the wall is less than the length of the wall and the width of the wall, for example, at least 20 times less than said length or than said width.

The wall may be generally flat, concave, convex, generally J-shaped, or generally S-shaped, ie presenting an inflection point. In the event that the wall is not flat, the length and width of the wall are the greatest dimensions of the wall when it is developed in a plane. The wall thickness is the dimension perpendicular to said plane.

The porous damping element allows the circulation of sea water through said damping element.

The pores can be formed by openings or holes, or by any other type of pores that allow the circulation of sea water through the damping element. The size of the pores is, for example, between 10 cm and 50 cm.

Each opening can have a circular or oval section, or a polygonal section, for example rectangular. Of course, any kind of shape can be considered.

The porous damping element can consist of a set of openings regularly or irregularly distributed along the wall, said openings allowing the passage of water through the wall.

The mobile element can be a fin.

The fin may extend in a plane oscillating about a substantially vertical median plane.

The axis of rotation may be horizontal.

The axis of rotation can be located at the level of the upper end of the mobile element.

As a variant, the axis of rotation can be located at the level of the lower end of the mobile element.

According to yet another variant, the axis of rotation may be vertical. In this case, the axis of rotation can be located at the level of a lateral end of the mobile element.

The upper end of the mobile element can be located above a certain maximum level of the water surface.

The maximum level can be calculated based on the highest tide level in the geographical area in which the device is installed and on a given wave amplitude level. In other words, said maximum level can be determined in such a way that, in case of high tide and large waves, the upper end of the mobile element is located above the surface of the water. Of course, in the event of an exceptional storm, the water can pass over the upper end of the mobile element.

The upper end of the damping element may be located above said determined maximum level of the water surface.

The lower end of the mobile element can be located at a distance between 0.5 and 2 meters from a seabed or an artificial surface.

In this way, a sea flow can circulate under the mobile element, in particular to raise the sediments and/or the sand and prevent their accumulation on the seabed or on the artificial surface. In particular, said accumulation can cause a blockage or a malfunction of the mobile element and require costly dredging operations.

The marine flow can be a natural flow and/or be caused by the alternating movement of the mobile element that creates local disturbances that cause an uplift effect.

The artificial surface can be formed, for example, by a frame on which the mobile element is mounted. The damping element can be fixed to the frame.

The lower end of the damping element can be located at a distance of less than 5 meters, for example between 0.2 and 5 meters from a seabed or an artificial surface.

The device may consist of several adjacent walls. The walls can be located on top of each other and/or offset from each other with respect to the direction of propagation of the gravity wave.

The damping element can have a lower end located close to the mobile element and an upper end located opposite the mobile element.

The axis of rotation of the mobile element can be integral with a frame fixed to a natural ground or seabed, or with a floating or submerged frame anchored to said natural ground.

The frame may consist of a base platform fixed to the natural ground or seabed, and posts or struts extending upwardly from the base platform, the axis of rotation being integral with the posts or spars.

The floating or submerged frame can be formed by a ship or a barge fitted out to receive the device.

The attenuation means may consist of a generator, for example electric or hydraulic, capable of converting the rotational movement of the mobile element around its axis into energy, for example electrical or hydraulic.

The generator is thus capable of generating a torque of resistance that tends to slow down the rotational movement of the mobile element, whatever the direction of rotation of the mobile element.

Thus, the mobile element participates both in the gravity wave attenuation function and in the energy conversion function.

It has been found that the presence of a damping element downstream of the mobile element can, depending in particular on the shape of said damping element and the resistance torque created, generate a more or less important resonance phenomenon that favors recovery. of energy with the help of the generator.

The generator can be hydraulic and/or electric. In this case, the rotation of the mobile element causes the translational movement of at least one piston connected to a control valve that regulates the flow of hydraulic fluid displaced by the piston towards high and low pressure reservoirs, generating a flow that drives a pressure difference generator.

A hydroelectric generator is known, in particular, from US 4490621.

As a variant, the device may lack a generator, the attenuation means consisting of at least one elastic element capable of exerting a torque of resistance that tends to oppose the movement of the mobile element, whatever the direction of rotation of the mobile element.

The device may consist of regulation means capable of regulating the electrical power or the voltage generated by the generator, when it is an electrical generator, based on the kinetic energy transmitted to the mobile element by the gravity wave. The adjustment means may be capable of regulating the resistance torque that opposes the movement of the mobile element.

The device may consist of means for adjusting the vertical position of the upper end of the mobile element.

Said adjustment means may be capable of adjusting the vertical position of the axis of rotation.

The device may consist of several moving elements whose axes of rotation are parallel and vertically offset relative to each other.

Description of the figures

Figure 1 is a schematic view of a device according to a first embodiment of the invention.

Figure 2 is a front view of the device.

Figure 3 is a top view of the device.

Figure 4 is a schematic view of the device illustrating in particular the means for energy conversion.

Figure 5 is a front view of a device according to a second embodiment of the invention.

Figure 6 is a top view of the device.

Figure 7 is a side view of the device.

Fig. 8 is a schematic view of a device according to a third embodiment.

Figures 9 to 19 illustrate different embodiments of the porous wall.

Figure 20 is a schematic perspective view of a set of adjacent devices.

Figure 21 is a detail and top view of part of the assembly of Figure 20.

Figure 22 is a schematic view of a set of devices according to the invention, mounted on a submerged frame and anchored to the ground.

Figure 23 is a top view of the installation illustrated in Figure 22.

Detailed description of the invention

Figures 1 to 4 illustrate a device 1 for attenuating an oceanic gravitational wave, for example waves, according to an embodiment of the invention. The device 1 is installed in a marine environment, near the coast, for example in a port area.

The device comprises a frame 2 including a base 3 formed, for example, by a raft, and posts 4 extending vertically from the base 3. The base 3 is fixed to a natural ground formed by a seabed.

The uprights 4 support a fin 6 which can rotate about an axis 7 whose ends are connected to the uprights 4. The axis 7 extends along a horizontal axis A. The axis 7 is located at the upper end of the fin 6. In this way, the fin 6 can rotate under the effect of waves, on both sides of a vertical median plane.

The fin 6 is positioned vertically such that the upper end of the fin 6 is located above a predetermined maximum level of the water surface.

The maximum level can be calculated based on the highest level of the tide in the geographical area where the device 1 is installed and on a determined wave amplitude level. In other words, said maximum level can be determined in such a way that, in case of high tide and large waves, the upper end of the fin 6 is located above the surface of the water. Of course, in the event of an exceptional storm, the water and the spray can pass over the upper end of the flap 6.

In addition, the lower end 8 of the fin 6 is located at a distance d (figure 2) of between 0.5 and 2 meters from the seabed or base 3.

In this way, a marine flow can circulate below the fin 6, in order to expel in particular the sediments and/or the sand and thus prevent their accumulation on the seabed or in the base 3. The marine flow can be a natural flow and/or be caused by the reciprocal movement of the fin 6 which creates local disturbances causing a washing effect.

The device 1 also includes wave attenuation means 20 capable of slowing down the rotation of the fin 6 around its axis A.

As illustrated in figure 4, the attenuation means 20 comprise at least one piston 9 driven in rotation by the rotation of the fin 6, for example by means of a connecting rod 10, the piston 9 being associated with a regulation valve 10 which regulates the flow of hydraulic fluid displaced by the piston towards the high and low pressure tanks 11, 12, generating a flow that drives a hydroelectric generator 13 by pressure difference. The electrical current produced by the generator is sent to an electrical network 14.

The actuation of piston 9 and generator 13 causes a resistance torque on shaft 7 to slow down the rotational movement of fin 6.

The device 1 also comprises regulation means 15 capable of regulating the electrical power or the voltage generated by the generator 13 as a function of the kinetic energy transmitted to the fin 6 by the gravity wave. The adjustment means 15 may be capable of regulating the resistance torque that opposes the movement of the flap, through the valve 10, to brake the flap, whatever the direction of rotation of the flap 6.

Fin 6 thus participates both in the gravitational wave attenuation function and in the energy conversion function.

The device 1 also comprises a member, here porous, in the form of a porous wall 16 and located downstream of the fin 6 with respect to the general direction of propagation of the gravity wave, illustrated in the figures by arrow D. The wall porous wall 16 comprises openings 17 that allow the circulation of sea water through said porous wall 16.

Each opening 17 may have a circular or oval cross section, or a polygonal cross section, for example rectangular. Of course, any form can be considered.

The porous wall 16 is attached to the frame 2 and here has a general S-shape with a zone

1

of inflection. Wall 16 has a lower end 18 located near flap 6 and an upper end 19 located opposite flap 6.

The upper end 19 of the porous wall 16 is located above said maximum determined water surface level.

The lower end 18 of the porous wall 16 is located at a distance of between 0.2 and 5 meters from the seabed or base 3.

The porous wall 16 further improves the attenuation of waves downstream of the fin 6.

Figures 5 to 7 illustrate an embodiment that differs from the one discussed above in that the device 1 comprises a plurality of movable fins 6 that are vertically displaced relative to each other, whose axes of rotation A are parallel and vertically displaced relative to each other. The axes of rotation A are located in the same vertical plane.

Each fin 6 can be associated with attenuation means 20 of the type mentioned above.

Figure 8 illustrates a third embodiment, which differs from that discussed with reference to Figures 1 to 4 in that the device 1 has a plurality of adjacent porous walls 16. The walls 16 are here located one above the other. The lower upstream ends 18 of the porous walls 16 are located in the same area while the upper downstream ends 19 of the walls 16 are staggered vertically and lie here in the same vertical plane.

Said embodiment further improves the attenuation of the waves downstream of the porous walls 16.

Figures 9 to 16 illustrate different embodiments of the porous walls 16.

Figure 9 illustrates an S-shaped porous wall 16, similar to that of the previous figures.

Figure 10 illustrates an oblique planar porous wall 16, having a lower upstream end 18 and an upper downstream end 19.

Figure 11 illustrates a convex porous wall 16 with an upward convexity.

Figure 12 illustrates a concave porous wall 16 with the concavity facing up.

Figure 13 illustrates a concave porous wall 16 with the concavity facing upwards.

Figure 14 illustrates an embodiment having a plurality of superimposed convex porous walls 16 spaced vertically apart. The convexities of the walls 16 are oriented upwards.

Figure 15 illustrates an embodiment comprising a plurality of superimposed concave porous walls 16 spaced vertically apart from each other. The concavities of the walls 16 are directed upwards.

Figure 16 illustrates an embodiment having a plurality of vertical porous walls 16 spaced apart in the direction of wave propagation.

Figure 17 illustrates an embodiment comprising an upper convex porous wall 16, whose convexity is oriented upwards, and a lower concave porous wall 16, whose concavity is upwards, said walls being joined by their lower upstream edges 18, by one side, and by its upper downstream edges 19, on the other.

Figure 18 illustrates a wall, of the non-porous type 16, with the general shape of a J. Said wall therefore does not allow the flow of water through it. In an alternative embodiment not shown, said J-shaped wall may also be porous.

Figure 19 illustrates an embodiment having at least two sets of porous walls 16, namely an upper set 25 and a lower set 26.

The upper assembly 25 comprises an upper convex porous wall 16, the convexity of which is oriented upwards, and a lower concave porous wall 16, the concavity of which is upwards, said walls being joined by their lower upstream edges 18, on one side, and by its upper edges downstream 19, by another.

The lower assembly 26 comprises an upper convex porous wall, the convexity of which is oriented upwards, and a lower concave porous wall, the concavity of which is oriented upwards, said walls being joined by their upper upstream edges, on one side, and by their lower downstream edges 19, on the other.

Of course, the number of sets 25, 26 can vary according to the needs.

Figures 20 and 21 illustrate an embodiment in which several devices 1 are arranged side by side and in the same row. Of course, several devices 1 can also be arranged in several different rows, for example staggered.

In the embodiment, the rising edges 21 of the uprights 4 are profiled to reduce the force exerted by waves or currents on said uprights 4.

Figures 22 and 23 illustrate an embodiment in which the frame 2 is buoyant and is kept submerged by means of the anchor 22 to the seabed 23, so that the upper end of the fin 6 of each device 1 is kept above the maximum level of determined water.

The anchor 22 can be made, for example, by means of cables. The rack 2 can be formed by a ship or a barge equipped to receive at least one device 1.

The frame 2 can be formed by a ship or barge conditioned to receive at least one device 1, having a base surface 24 from which the uprights 4 extend vertically. The porous walls 16 are formed by vertical walls with openings 17 in the lower part of said vertical walls 16. The vertical walls 16 can be pre-existing in the ship or barge 3, and the openings 17 are made when the ship or barge 3 is fitted out.

As in the previous case, a distance d of between 0.5 and 2 meters is maintained between the surface of the base 24 and the lower end 8 of each fin 6.

As illustrated in Figure 22, several fins 6 can be mounted in line and adjacent to each other on the same floating frame 3, the axes of rotation A of the fins 6 being coaxial.

1

Claims (10)

1. Device (1) to attenuate an oceanic gravity wave, installed in a marine environment and comprising: - at least one mobile element (6) in rotation around an axis (A), capable of moving in rotation and alternately in two opposite directions of rotation, under the effect of said gravity wave, - attenuation means (20) capable of slowing down the rotation of the mobile element (6) around its axis (A), - at least one damping element (16) located downstream of said mobile element (6) with respect to the general direction of propagation (D) of the gravity wave, the damping element (16) being in the form of at least one wall porous and allowing the circulation of sea water through said damping element (16). Device (1) according to claim 1, characterized in that the mobile element (6) is a fin. Device (1) according to one of the preceding claims, characterized in that the axis of rotation (A) is horizontal. Device (1) according to claim 3, characterized in that the axis of rotation (A) is located at the level of the upper end of the mobile element (6). Device (1) according to one of the preceding claims, characterized in that the upper end of the mobile element (6) is located above a determined maximum level of the water surface. Device (1) according to one of the preceding claims, characterized in that the lower end (8) of the mobile element (6) is located at a distance of less than 5 m from a seabed (23) or from an artificial surface ( 3). Device (1) according to one of the preceding claims, characterized in that the axis (A) of rotation of the mobile element (6) is integral with a frame (3) fixed to a natural ground or to the seabed, or with a floating or submerged frame (3) anchored to said natural ground (23). Device (1) according to one of the preceding claims, characterized in that the attenuation means (20) consist of a generator (13) capable of transforming the rotational movement of the mobile element (6) around its axis (A) in energy. Device (1) according to claim 7 or 8, characterized in that it consists of means for adjusting the vertical position of the upper end of the mobile element (6). Device (1) according to one of the preceding claims, characterized in that it consists of several mobile elements (6) whose rotation axes (A) are parallel and vertically offset relative to each other. 1