FR3102492A1 - Device for the attenuation of an oceanic gravity wave - Google Patents

Abstract

The invention relates to a device (1) for the attenuation of an oceanic gravity wave, installed in a marine environment and comprising, - at least one movable member (6) in rotation about an axis (A), capable of be moved 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 movable member (6) around its axis (A), - at least one porous member (16) located downstream of said movable member (6) relative to the general direction of propagation (D) of the gravity wave, said porous member (16) allowing circulation seawater through said porous member (16). Figure to be published with the abstract: Figure 1.

Description

Device for the attenuation of an oceanic gravity wave

Technical field of the invention

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

State of the prior art

In fluid mechanics, by gravity wave is meant a wave moving on the free surface of a fluid subjected to gravity. In the marine environment, waves or swells are examples of gravity waves.

The coastal strip is a highly urbanized area and has many 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 phenomena that erode the coastline and damage the facilities there, especially in port areas.

Many structures are designed to provide protection against swells, such as breakwaters and dikes. The realization of such massive structures is expensive. It also requires neutralization of the port areas concerned for long periods of time and modifies the landscape of the coastline.

Documents FR 2 731 725 and GB 992 216 disclose porous box structures making it possible to dissipate or attenuate the swell.

It is also known to use a device comprising a movable shutter rotating about an axis and at least partially submerged, the shutter being moved by the movement of the swell. The kinetic energy transmitted to the shutter is transformed into electrical energy via a generator.

Such energy conversion devices are known in particular from documents EP 3 175 111, EP 1 861 618, EP 2 817 509, US 9 902 467 and US 10 132 289.

The invention aims to propose a device making it possible to attenuate an oceanic gravity wave with increased efficiency compared to the devices of the prior art and which can be installed in a marine environment, in particular in a port area, or more generally. from the coast, in a simple and inexpensive way.

Presentation of the invention

To this end, the invention relates to a device for the attenuation of an oceanic gravity wave, installed in a marine environment and comprising,
- at least one movable member in rotation about an axis, capable of being displaced in rotation and alternately in two opposite directions of rotation, under the effect of said gravity wave,
- attenuation means capable of slowing down the rotation of the movable member around its axis,
- at least one damping member located downstream of said movable member relative to the general direction of propagation of the gravity wave.

The means of attenuation make it possible to attenuate the wave of gravity, in particular the swell, in contact with the moving part. The damping member further improves the attenuation downstream of the movable member. It has in particular been observed that the presence of a damping member makes it possible, in certain cases which depend in particular on the shape and dimensions of said damping member, to reduce by a factor greater than 2, the amplitude of the oceanic gravity wave downstream of the device, by comparison with the same device without the damping member.

The damping member may be in the form of at least one wall.

Said wall can also be referred to as the damping range.

Such a wall can extend along a first dimension forming its length, along a second dimension forming its width and a third dimension forming its thickness. The length of the wall is greater than or equal to the width of the wall. The wall thickness 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 said width.

The wall may have a general planar, concave, convex, or S-shaped shape, that is to say having an inflection point. In the case where the wall is not planar, the length and the width of the wall are the largest dimensions of said wall when it is developed on a plane. The wall thickness is the dimension perpendicular to said plane.

The damping member may be porous and may allow the circulation of sea water through said damping member.

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

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

The porous damping member may include a set of openings distributed evenly or irregularly along the wall, said openings allowing the passage of water through the wall.

The damping member may be non-porous and thus be devoid of openings passing through said damping member.

The movable member can be a shutter.

The shutter may extend in a plane oscillating around a substantially vertical mid-plane.

The axis of rotation can be horizontal.

The axis of rotation may be located at the upper end of the movable member.

Alternatively, the axis of rotation can be located at the lower end of the movable member.

According to yet another variant, the axis of rotation can be vertical. In this case, the axis of rotation may be located at or at a lateral end of the movable member.

The upper end of the movable member may be located above a determined maximum level of the water surface.

The maximum level can be calculated according to the level of the highest tide in the geographical area where the device is installed and a determined level of swell amplitude. In other words, said maximum level can be determined so that, in the event of high tide and heavy swell, the upper end of the movable member is located above the surface of the water. Of course, in an exceptional storm, water can pass over the upper end of the movable member.

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

The lower end of the movable member may be located at a distance of between 0.5 and 2 meters from a seabed or an artificial surface.

In this way, a marine flow can circulate under the movable member, so as to drive away sediments and / or sand in particular and thus prevent their accumulation on the seabed or on the artificial surface. Such an accumulation can in particular cause a blockage or malfunction of the movable member and require expensive dredging operations.

The marine flow can be a natural flow and / or be caused by the reciprocating movement of the mobile member creating local disturbances causing a hunting effect.

The artificial surface can be formed, for example, by a frame on which the movable member is mounted. The damping member can be attached to the frame.

The lower end of the damping member may be located at a distance of between 1 and 5 meters from a seabed or an artificial surface.

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

The damping member may have a lower end located near the movable member and an upper end located opposite the movable member.

The axis of rotation of the movable member may be integral with a frame fixed to a natural ground or seabed, or a floating or submerged frame anchored to said natural ground.

The frame may include a raft fixed to the natural ground or seabed, and poles or uprights extend upward from the raft, the axis of rotation being integral with the uprights or poles.

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

The attenuation means may include an electric generator capable of transforming the rotational movement of the movable member around its axis into electrical energy.

The electric generator is thus able to generate a resistive torque tending to slow down the rotational movement of the movable member, regardless of the direction of rotation of the movable member.

The mobile organ thus participates both in the function of attenuating the gravity wave and in the function of energy conversion.

It has been observed that the presence of a damping member downstream of the movable member can, depending in particular on the shape of said damping member and the resistive torque created, generate a more or less significant phenomenon of resonance favoring energy recovery using the electric generator.

The generator can be of the hydraulic and / or electric type. In this case, the rotation of the movable member causes the translational movement of a piston connected to a regulating valve which regulates the flow of hydraulic fluid moved by the piston to high pressure and low pressure reservoirs, generating a flow entraining a generator by pressure difference.

A hydroelectric generator is known in particular from document US Pat. No. 4,490,621.

As a variant, the device may be devoid of an electric generator, the attenuation means comprising at least one elastic member capable of exerting a resistive torque tending to oppose the movement of the movable member, regardless of the direction of rotation of the movable organ.

The device may include regulating means capable of regulating the electric power or the voltage generated by the electric generator as a function of the kinetic energy transmitted to the mobile organ by the wave of gravity. The regulating means may be able to regulate the resistive torque opposing the movement of the movable member.

The device may include means for adjusting the vertical position of the upper end of the movable member.

Said adjustment means may be able to adjust the vertical position of the axis of rotation.

The device may include several movable members whose axes of rotation are parallel and vertically offset with respect to each other.

Brief description of the figures

is a schematic view of a device according to a first embodiment of the invention,

is a front view of the device,

is a top view of the device,

is a schematic view of the device illustrating in particular the means allowing the conversion of energy,

is a front view of a device according to a second embodiment of the invention,

is a top view of the device,

is a side view of the device,

is a schematic view of a device according to a third embodiment,

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illustrate different embodiments of the porous wall,

is a schematic perspective view of a set of adjacent devices,

is a detail view from above of part of the assembly of figure 19,

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

is a top view of the installation illustrated in figure 21.

Detailed description of the invention

Figures 1 to 4 illustrate a device 1 for attenuating an oceanic gravity wave, for example swell, according to one 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 comprising a base 3 formed for example by a raft, and uprights 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 flap 6 movable in rotation around a shaft 7, the ends of which are connected to the uprights 4. The shaft 7 extends along a horizontal axis A. The shaft 7 is located at the level of the upper end of the shutter 6. The shutter 6 can thus be moved in rotation under the effect of the swell, on either side of a vertical median plane.

The shutter 6 is positioned vertically so that the upper end of the shutter 6 is located above a determined maximum level of the water surface.

The maximum level can be calculated according to the level of the highest tide in the geographical area where device 1 is installed and a determined amplitude level of the swell. In other words, said maximum level can be determined so that, in the event of high tide and heavy swell, the upper end of flap 6 is located above the surface of the water. Of course, in an exceptional storm, water and spray can pass over the upper end of shutter 6.

Furthermore, the lower end 8 of the flap 6 is located at a distance d (Figure 2) of between 0.5 and 2 meters from the seabed or from the base 3.

In this way, a marine flow can circulate under the shutter 6, so as to drive away in particular the sediments and / or the sand and thus avoid their accumulation on the seabed or on the base 3. The marine flow can be a natural flow and / or be caused by the reciprocating movement of the shutter 6 creating local disturbances causing a hunting effect.

The device 1 also comprises means 20 for attenuating the swell capable of slowing down the rotation of the shutter 6 around its axis A.

As illustrated in FIG. 4, the attenuation means 20 comprise a piston 9 driven in rotation by the rotation of the flap 6, for example by means of a connecting rod 10, the piston 9 being associated with a regulating valve 10 which regulates the flow of hydraulic fluid moved by the piston to high pressure and low pressure reservoirs 11, 12, generating a flow driving a hydroelectric generator 13 by pressure difference. The electrical current produced by the generator is then sent to an electrical network 14.

The actuation of the piston 9 and of the generator 13 drives a resistive torque at the level of the shaft 7 so as to slow down the rotational movement of the shutter 6.

The device 1 further comprises regulating means 15 capable of regulating the electric power or the voltage generated by the generator 13 as a function of the kinetic energy transmitted to the shutter 6 by the gravity wave. The regulating means 15 may be able to regulate the resistive torque opposing the movement of the shutter, through the valve 10, so as to brake the shutter, regardless of the direction of rotation of the shutter 6.

Component 6 thus participates in both the gravity wave attenuation function and the energy conversion function.

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

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

The porous wall 16 is fixed to the frame 2 and here has a general S-shape with an inflection zone. The wall 16 has a lower end 18 located near the shutter 6 and an upper end 19 located opposite the shutter 6.

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

The lower end 18 of the porous wall 16 is located at a distance of between 1 and 5 meters from the seabed or from the base 3.

The porous wall 16 further improves the attenuation of the swell downstream of the shutter 6.

Figures 5 to 7 illustrate an embodiment which differs from that explained above in that the device 1 comprises several movable shutters 6 offset vertically with respect to each other, whose axes A of rotation are parallel and vertically offset one by one. compared to others. The axes A of rotation are here located on the same vertical plane.

Each component 6 can be associated with attenuation means 20 of the aforementioned type.

FIG. 8 illustrates a third embodiment, which differs from that exposed with reference to FIGS. 1 to 4 in that the device 1 comprises several porous walls 16 adjacent. The walls 16 are here located one above the other. The lower upstream ends 18 of the porous walls 16 are located at the same zone while the upper downstream ends 19 of the walls 16 are vertically offset and are here located on the same vertical plane.

Such an embodiment makes it possible to further improve the attenuation of the swell downstream of the porous walls 16.

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

FIG. 9 illustrates a porous wall 16 of general S shape, similar to that of the preceding figures.

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

FIG. 11 illustrates a convex porous wall 16, the convexity of which faces upwards.

FIG. 12 illustrates a concave porous wall 16, the concavity of which faces upwards.

Figure 13 illustrates a concave porous wall 16, the concavity of which faces upstream.

FIG. 14 illustrates an embodiment comprising several superimposed porous convex walls 16, spaced vertically from one another. The convexities of the walls 16 face upwards.

FIG. 15 illustrates an embodiment comprising several porous walls 16 superimposed concave, vertically spaced from each other. The concavities of the walls 16 face upwards.

FIG. 16 illustrates an embodiment comprising a convex upper porous wall 16, the convexity of which is turned upwards and a concave lower porous wall 16, the concavity of which faces upwards, said walls being connected by their lower upstream edges18, on the one hand, and by their upper downstream edges 19, on the other hand.

FIG. 17 illustrates an embodiment comprising at least two sets of porous walls 16, namely an upper assembly 25 and a lower assembly 26.

The upper assembly 25 comprises a convex upper porous wall 16, the convexity of which faces upwards and a concave lower porous wall 16, the concavity of which faces upwards, said walls being connected by their lower upstream edges18, with a on the one hand, and by their upper downstream edges 19, on the other hand.

The lower assembly 26 comprises a convex upper porous wall 16, the convexity of which faces upwards and a concave lower porous wall 16, the concavity of which faces upwards, said walls being connected by their upper upstream edges, with a on the one hand, and by their lower downstream edges 19, on the other hand.

Of course, the number of sets 25, 26 can vary as needed.

FIG. 16 illustrates an embodiment comprising several porous vertical walls 16 spaced apart from each other in the direction of propagation of the swell.

Figures 19 and 20 illustrate an embodiment in which several devices 1 are arranged adjacent and on the same row. Of course, several devices 1 can also be arranged in several different rows, for example staggered.

In the embodiment, the upstream edges 21 of the uprights 4 are profiled so as to reduce the force exerted by the swell or the currents on said uprights 4.

Figures 21 and 22 illustrate an embodiment in which the frame 2 is floating and is kept submerged by anchoring 22 to the seabed 23 so that the upper end of the flap 6 of each device 1 is held above the maximum determined water level.

The anchorage 22 can be achieved by means of cables, for example. The frame 2 can be formed by a ship or a barge fitted out to receive at least device 1.

This then has a base surface 24 from which uprights 4 extend vertically upwards. The porous walls 16 are formed by vertical walls, the openings 17 of which are formed in the lower part of said vertical walls 16. The vertical walls 16 can be pre-existing on the ship or the barge 3, the openings 17 being made during the operation. fitting out of the ship or barge 3.

As before, a distance d of between 0.5 and 2 meters is maintained between the base surface 24 and the lower end 8 of each shutter 6.

As illustrated in FIG. 22, several flaps 6 can be mounted in line and adjacent to the same floating frame 3, the axes A of rotation of the flaps 6 being coaxial.

Claims (12)

Device (1) for the attenuation of an oceanic gravity wave, installed in a marine environment and comprising:
- at least one movable member (6) in rotation about an axis (A), capable of being moved 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 movable member (6) around its axis (A),
- at least one damping member (16) located downstream of said movable member (6) relative to the general direction of propagation (D) of the gravity wave. Device (1) according to claim 1, characterized in that the damping member (16) is in the form of at least one wall. Device according to claim 2, characterized in that the damping member is porous and allows the circulation of sea water through said damping member (16). Device (1) according to one of claims 1 to 3, characterized in that the movable member (6) is a shutter. Device (1) according to one of claims 1 to 4, characterized in that the axis (A) of rotation is horizontal. Device (1) according to Claim 5, characterized in that the axis (A) of rotation is located at the level of the upper end of the movable member (6). Device (1) according to one of claims 1 to 6, characterized in that the upper end of the movable member (6) is located above a determined maximum level of the water surface. Device (1) according to one of claims 1 to 7, characterized in that the lower end (8) of the movable member (6) is located at a distance of between 0.5 m and 2 m from a seabed (23) or an artificial surface (3). Device (1) according to one of claims 1 to 8, characterized in that the axis (A) of rotation of the movable member (6) is integral with a frame (3) fixed to a natural ground or bottom marine, or a frame (3) floating or submerged anchored to said natural ground (23). Device (1) according to one of claims 1 to 8, characterized in that the attenuation means (20) comprise an electric generator (13) capable of transforming the rotational movement of the movable member (6) around its axis (A) in electrical energy. Device (1) according to claim 9 or 10, characterized in that it comprises means for adjusting the vertical position of the upper end of the movable member (6). Device (1) according to one of claims 1 to 11, characterized in that it comprises several movable members (6) whose axes (A) of rotation are parallel and offset vertically with respect to each other.