EP3259470A1

EP3259470A1 - System for generating waves in a pool

Info

Publication number: EP3259470A1
Application number: EP16707677.7A
Authority: EP
Inventors: Aurélien BABARIT; Simon DELVOYE
Original assignee: Centre National de la Recherche Scientifique CNRS; Ecole Centrale de Nantes
Current assignee: Centre National de la Recherche Scientifique CNRS; Ecole Centrale de Nantes
Priority date: 2015-02-20
Filing date: 2016-02-22
Publication date: 2017-12-27
Also published as: FR3033003B1; US20180135322A1; FR3033003A1; WO2016131992A1

Abstract

The invention relates to a system for generating waves in a pool (1000), said system comprises, in the region of at least one wall of said pool, at least one water intake mouth which is connected to a supply source (4001) by means of a network of pipes (3004), said network of pipes (3004) comprising at least one pump (5003) which is capable of alternately transferring water from the supply source (4001) to the pool (1000) and vice versa, said pump (5003) being controlled so as to generate, in the region of the water intake mouth, an oscillating flow which is alternately oriented towards the pool (1000) and then towards the supply source (4001).

Description

SYSTEM FOR GENERATING WAVES IN A BASIN

The invention relates to a system for generating waves in a pool. The invention also relates to a system for recovering wave energy.

Wave generation in a basin is usually done using oscillating mechanical devices, such as floats or vertical flap drummers. These devices oscillate vertically or horizontally by moving a volume of water, which generates waves.

Current generation is also possible by means of pumps usually placed on the edges or at the bottom of the basin. In this case, a closed-loop operation is possible thanks to a recirculation pipe placed under the basin.

Such wave generation systems generally have problems related to their mechanical complexity. This complexity is due in particular to the presence of many moving parts, and, in the case of drummers with vertical shutters of "dry-back" type, the need to compensate for the hydrostatic thrust applied to the wet side of the drummer.

Another problem of such wave generation systems is that they require end stops to be provided which limit the maximum amplitudes of the movements. This limitation of the amplitude of the movement also limits the amplitude of the waves generated.

Another problem with such systems is that the Combined generation of waves and current requires the implementation of two types of devices: floats, for example, for wave generation and pumps for current generation. This is additional source of complexity.

Concerning wave energy recovery, also called wave energy, energy recovery systems using turbines exist, nevertheless these systems are:

- Either simple and inexpensive, but also inefficient such as breaking systems or oscillating water columns;

- Efficient, but complex and expensive such as oscillating systems with active control. As a result, in both cases the cost of energy is too high compared to the market.

An object of the invention is to solve the problems of wave generation systems in a pool known in the state of the art. The invention aims in particular to provide a system for generating waves in a basin that is simple and effective, and is not limited mechanically for the amplitude of the waves generated. The invention also aims to propose a system for simultaneous generation of waves and current that is simple and easy to implement.

Another objective of the invention is to propose a wave energy recovery system that is at the same time simple, inexpensive and efficient.

The invention relates to a system for generating waves in a basin, characterized in that it comprises, at least one wall of said basin, at least one water inlet mouth connected to a source of supply by a network of pipes, said network of pipes comprising at least one pump adapted to exchange water alternately from the supply source to said basin and vice versa, said pump being controlled so as to generate at the water inlet mouth an oscillating flow oriented alternately to the basin and then to the source of supply.

Thus, the system according to the invention uses pumps for wave generation. These generate an oscillating flow that locally creates a vertical variation in the surface elevation of the water, this variation propagates and thus effectively generates waves.

In more technical terms, the oscillating flow creates a boundary condition in the fluid that locally mimics wave kinematics. The propagation of this boundary condition generates waves.

In addition, the use of pumps eliminates end stops that limit the maximum range of motion. Thus, the amplitude of the waves generated is also not limited by these stops.

Oscillating flow rate means a flow whose quantity of water per second oscillates between a minimum value and a maximum value. The pump used in this system can be any type of pump capable of pumping water from the tank to the basin and vice versa. It is possible, for example, to use any type of motor pump, in particular a propeller pump. According to one embodiment of the invention, the oscillating flow rate generated has a non-zero average. Imposing a non-zero average flow oscillating flow makes it possible to generate a current in addition to waves. Thus, the same device for generating waves is also used to generate a current. In this way, waves and current can be generated simultaneously without any need to add additional devices.

According to another embodiment of the invention, the system also comprises a convergent having inclined walls, placed at the outlet of the water inlet mouth. Such a convergent makes it possible to diffuse the jet generated by the pump to prevent it being concentrated in a reduced zone. This makes it possible to optimize the profile of the flow created so as to get as close as possible to a conventional profile of a wave. Thus, the performance of the device is further improved.

According to another embodiment of the invention, the inlet mouth of water is inclined at an angle alpha relative to the bottom of the basin.

Advantageously, the outlet of the water inlet mouth is provided with a structure in the form of a honeycomb. Such a structure in the form of a honeycomb makes it possible to break any swirling structures that would be generated by the pump. According to one embodiment of the invention, the supply of water pump is from a reservoir located upstream of the water inlet mouth. This tank is, for example in the open air. Advantageously, the basin has an end opposite to the wall comprising the inlet water mouth, and the reservoir is connected to the opposite end by a second pipe network. For example, these pipes pass under the bottom of the basin. According to one embodiment of the invention, the tank in the open air consists of a second basin, which may be, for example, identical to the initial pool.

According to a variant, the supply of the water pump is directly in the basin, the pipe network connecting the water inlet mouth to at least one opening at the bottom of the basin. Preferably the pipe network connects the inlet mouth of water to several openings at the bottom of the basin. Such a supply directly to the bottom of the basin has the advantage of not requiring an additional tank.

Advantageously, the opening (s) at the bottom of the pool is (are) located at an end opposite to that comprising the wave generating pipe. This makes it possible not to disturb the wave generation. Advantageously, the opening at the bottom of the basin has a flared shape. Such a shape also makes it possible to limit disturbances to wave generation.

According to another embodiment, the mouth water inlet is integrated with a structure maintained floating by sliding along a vertical guide column. The fact that the water inlet is integrated in a floating structure optimizes wave generation. Indeed, in this case the oscillating flow is generated near the surface of the water while avoiding the intake of air when the pump operates in suction.

Advantageously, the pump is placed upstream of the water inlet mouth on a support located above the water level. This configuration notably makes it easier to access the pump for maintenance.

According to one variant, the wave generation system comprises several water inlet mouths placed one above the other.

The invention also relates to a system for recovering energy from waves at sea, characterized in that it comprises a sealed support structure comprising at least one water inlet mouth connected to a network of exhaust pipes d. water, said network of water discharge pipes comprising,

at least one pump controlled so as to generate a pressure drop proportional to the acceleration of the water flow in order to reduce the effects of inertia related to the mass of water contained in the pipe network, and

- At least one turbine driven by the flow of water to produce electrical energy. Thus, the energy recovery system proposed by the invention is simple and inexpensive since it relies on the use of pumps for the generation of a flow and turbines for the production of electrical energy. In addition, the control of the flow makes it possible to reduce the apparent inertia of the system. As a result, the efficiency of the turbine during energy recovery cycles is improved. Thus, the overall efficiency of the system is also improved.

By reducing the apparent inertia, it is meant that, without control, the system behaves as a mass-damper assembly subjected to an excitation force. To maximize overall efficiency, the flow velocity must be in phase with the excitation force. Without piloting, the term mass is dominant. The flow velocity is then 90 ° out of phase with the excitation force. The overall yield is low. With the control of the flow by the pump, the apparent mass is reduced so that the damping term is dominant. The flow velocity is then in phase with the excitation force and the overall efficiency is considerably improved.

It should be noted that the water discharge network also serves as a supply network for the water pump when it is in discharge mode.

The pump used in this energy recovery system can also be any type of pump capable of pumping water from the tank to the basin and vice versa. It is possible, for example, to use any type of motor pump, in particular a propeller pump. In a variant, the pump and the turbine are coupled. Coupling means that the pump and the turbine belong to the same device or form the same device. For example, the turbine can be replaced by the propellers of a propeller pump.

According to one application, the speed of the flow is measured by a sensor positioned in the driving network. Such a sensor is for example a flow meter.

According to one embodiment of the invention, the waterproof support structure is a wall of a dike. Thus, one can install this system in shallow water on the wall of a dike, for example. In this way we share the protection of the coastline and the production of energy.

According to another embodiment, the water inlet mouth is mounted floating on a float held in position by anchoring lines. This structure allows the installation of the system at great depth.

According to one embodiment of the invention, the discharge of water is directly in the sea, a vertical pipe being emerged at a determined depth. In the case where the system is positioned at great depth, the pipe is emerged directly into the water at a determined depth considered sufficient. Such a depth must be at least half the wavelength of the dominant wave on site. Such a pipe can be held in position by a solid structure. On the other hand, in the case of a system positioned at shallow depth, it is preferable that the pipe crosses the wall of the dam and opens out. Dominant wave on site is the most common wave in an area.

According to another embodiment of the invention, the outlet of the water inlet mouth is provided with a convergent inclined walls. These inclined walls have the advantage of concentrating the flow of water at the inlet of this water inlet mouth.

Other characteristics and advantages will appear more clearly on reading the following description, of preferred embodiments, given by way of non-limiting examples, in relation to the appended drawings in which:

FIG. 1 represents a system for generating waves in a basin according to the invention without which the pump is supplied with water by a reservoir located upstream of the water inlet mouth;

FIG. 2 represents a variant of the system of FIG. 1 in which the supply of the pump with water is done directly in the basin;

- Figure 3 shows a variant of the system of Figure 2 in which the water inlet is floating;

FIGS. 4 and 5 represent two variants of a wave energy recovery system that can be used at low depth;

FIG. 6 represents a wave energy recovery system that can be used at great depth;

Figure 7 shows a system of wave generation similar to the system of Figure 1 wherein the inlet water mouth is inclined at an angle;

Figure 8 shows a system of Figure 7 wherein the basin communicates further with the reservoir by a pipe arranged in the bottom of the basin;

Figure 9 the system of Figure 8 which comprises wherein the water inlet mouth further comprises a honeycomb;

FIG. 10 represents a system similar to the system of FIG. 8 which comprises two superimposed water inlet mouths;

- Figure 11 shows a system similar to the system of Figures 1 and 7 wherein the reservoir is a second basin.

Generation of waves An example of a wave generation system in a basin 1 is shown in FIG. 1. This system comprises a water inlet 2 comprising a pipe 3 through which the basin 1 communicates with a tank 4. A pump 5 positioned in the pipe 3 is controlled so as to generate a flow of water having an oscillating flow oriented alternately towards the basin 1 and then to the reservoir 4. The oscillating flow flow thus created makes it possible to generate waves 6 in the basin 1. In the example of Figure 1, the water inlet mouth 2 comprises a convergent having inclined walls 7. This convergent allows to diffuse the flow generated by the pump to avoid that it is concentrated in a reduced zone. Diffusion of the generated flow allows to have waves with a better profile, that is to say approaching the profile of the waves at sea.

The water inlet mouth 2 is also equipped at its outlet with a structure in the form of a honeycomb 7. This structure 8 makes it possible to break any swirling structures that would be generated by the pump.

The wave generation system of FIG. 1 also makes it possible to generate a current without the need to add other devices. For this, a non-zero average flow rate is imposed on the oscillating flow generated at the outlet of the water inlet mouth.

Positive flow designates the flow rate generated by the pump when it is oriented in a preferred direction, for example towards the basin. When the pump is oriented in the opposite direction of the preferred direction, the flow is considered negative. By non-zero average flow rate it is meant that the oscillatory flow generated by the pump is oriented more in one direction than in the other. Thus, to generate a current in the basin, the pump is oriented more in the direction of the basin than in the opposite direction. A variant of the wave generation system of FIG. 1 is represented by FIG.

This system comprises a basin 1000 comprising a wall 2000 forming a water inlet and a pipe 3000 through which the pool 1000 communicates with a reservoir 4000. A pump 5000 positioned in the pipe 3000 is controlled so as to generate a flow of water having an oscillating flow oriented alternately to the basin 1000 and then to the reservoir 4000, to generate waves 6000 in the basin 1000. This system comprises, with respect to the system of FIG. 1, the following particularities:

- the bottom of the tank is lower than the bottom of the basin. This has the advantage of allowing a tilt of the pipe.

the pipe 3000 is inclined at an angle to the bottom of the basin 7000. The advantage of such inclination is to optimize the profile of the current generated in the basin in the case of wave generation and current.

- Basin has a range of 8000 damping waves, whose interest is to dampen the waves generated when they arrive at the opposite end of 2001 of the wall 2000 of the pool 1000. The reservoir 4000 is for example a reservoir to the open air.

The angle a is for example between 0 and 15 degrees, preferably 5 degrees.

FIG. 8 represents a variant of the embodiment of FIG. 7, in which the tank 1000 has under bottom 7000, a pipe or pipe network 9000 allowing communication between the bottom 7000 of the basin 1000 and the tank 4000. 8, the pipe 9000 opens into the bottom 7000 of the basin 1000 at an opening 1001 at the level of the opposite end 2001 of the wall 2000 forming the water inlet mouth.

The pipe 9000 has the advantage of allowing the flow of a current generated by the pump when a non-zero flow is imposed. The circulation of the current generated is from the basin to the tank, as shown by the arrows.

FIG. 9 represents a system similar to the system of FIG. 8, but therefore which the inlet water inlet 2000 comprises a honeycomb-shaped structure 10000.

FIG. 10 represents a system similar to the system of FIG. 9, but therefore which inlet mouth 2000 comprises the honeycomb structure 10000 and two superimposed conduits 3001, 3002 respectively provided 5001, 5002. According to a variant this system does not include a honeycomb.

FIG. 11 represents a system similar to the system of FIGS. 1 and 7 in which the reservoir is in the shape of a second basin 4001.

This second basin 4001 may be identical to or different from the initial basin 1000.

The advantage of this embodiment is to allow to generate waves and / or current in the two basins. In addition, in this embodiment the pipe 3004 comprises a pump 5003 and honeycomb structures 10001, 10002 respectively on the side of the initial basin 1000 and on the side of the second basin 4001. Nevertheless, these structures in the form of Honeycomb 10001, 10002 are optional.

In the same way, we can have several pipes each provided with a pump and which are arranged next to each other and / or superimposed.

It is also possible that the pipe or pipes, inclined (s) to one of two basins 1000, 4001. Of course for all embodiments presented, it is possible to generate power in addition to the generation waves.

A second embodiment of a wave generation system according to the invention is shown in FIG. 2. This system is identical to the preceding system except with regard to the supply source of the pump. Instead of having a reservoir, the supply of the pump 15 is directly in the basin 10. This supply is through a pipe 19 via an opening 11 which is at the bottom of the basin. In order not to disturb the generation of waves in the basin, it is preferable that this opening be as far as possible from the inlet water mouth 12. It is also preferable that this opening has a flared shape. This opening 11 can also be replaced by several small openings at the bottom of the basin 10 connected to the pipe 19.

FIG. 3 represents a variant of the embodiment of FIG. 2. In this case, the water inlet mouth 22 is floatably mounted along a vertical guide column 31. This arrangement makes it possible to generate a flow. oscillating close to the surface of the water. This arrangement also makes it possible to avoid the intake of air when the pump is operating in suction since the water inlet mouth 22 follows the drop and the rise of the wave level, that is to say the passage from a peak to a hollow. To further improve the wave generation system, the pump 25 is mounted upstream of the water inlet mouth on a support 32 located above the water level. The pump 25 is connected to the water inlet mouth 22 by a flexible pipe 30. The other elements of this wave generation system are unchanged with respect to the system of FIG. 2. The operation of the pump also remains the same to the two previous examples. Wave energy recovery

An example of a system for recovering energy from waves 100 at sea is represented in FIG. 4. This system comprises a water inlet port 101 comprising a pipe 102 connected to a tank 103. This pipe 102 comprises a couple pump / turbine 104 controlled so as to efficiently generate electrical energy from the kinetic energy of the waves. The water inlet mouth is positioned in a sealed structure 105, for example the wall of a dike. A convergent 106 having inclined walls is positioned on this watertight structure 105 at the inlet of the water inlet mouth so as to converge the flow of water towards the inlet of this inlet water mouth, which has the effect of accelerating the flow. To optimize the efficiency of the turbine, the pump is controlled to produce a pressure drop proportional to the acceleration in order to reduce the apparent inertia of the water contained in the pipe network. To do this, a sensor 107 positioned in the pipe measures the speed of the flow continuously. FIG. 5 represents a second embodiment of a wave energy recovery system according to the invention. This system is identical to the system of Figure 4, except for the discharge of water and the supply of the pump. Instead of having a tank, the evacuation of water when the pump is suctioning and the supply of the pump when it is in discharge mode, this is through a pipe 108 via an opening 109 in the sealed structure 105. It is preferable that this opening 109 be as deep as possible in order to avoid disturbing the measurements of the sensor 107. It is also preferable to open this pipe further out, that is to say, as far as possible from the sensor. FIG. 6 represents a wave energy recovery system according to the invention that can be used at great depth. In this system, the water inlet mouth 200 is mounted on a float 201 held in position by anchor lines 202. The inlet water inlet 200 is connected to a pipe

203 emerged into the water at a sufficient depth, for example 50m below the water level. This ends with a convergent opening 204. A solid structure 205, integral with the structure 201, serves to maintain the pipe 203. In the same way as for the embodiments described with reference to FIGS. 5, the pump / turbine pair 206 cooperates with a sensor 207 positioned upstream of the inlet water inlet 200. The control of this system also remains identical to the systems of FIGS. 4 and 5. Optionally this system also comprises a convergent positioned at the inlet of the water inlet mouth to concentrate the flow of water at the inlet of the water inlet mouth 200.

Claims

1. System for generating waves in a basin, comprising, at the level of at least one wall of said basin, at least one inlet mouth connected to a source of supply via a network of conduits, said network of pipes comprising at least one pump capable of exchanging water alternately from the supply source to the basin and vice versa, said pump being controlled so as to generate at the water inlet mouth an oscillating flow oriented alternately towards the basin and then to the source of supply, characterized in that the pump is supplied with water from a reservoir in the open air located upstream of said water inlet.

2. Wave generating system according to claim 1, characterized in that said oscillating flow rate has a non-zero average.

3. System according to one of claims 1 or 2, characterized in that it also comprises a convergent having inclined walls, placed at the outlet of the water inlet mouth.

4. Wave generation system according to one of the preceding claims, characterized in that the inlet water mouth is inclined at an angle alpha relative to the bottom of the basin.

Wave generating system according to one of the preceding claims, characterized in that the outlet of the inlet water outlet is provided with a structure in the shape of a honeycomb.

6. Wave generating system according to one of the preceding claims, characterized in that the basin has an end opposite to the wall comprising the water inlet mouth, and in that the tank in the open air is connected to the opposite end by a second pipe network.

7. Wave generating system according to one of the preceding claims, characterized in that the tank in the open air consists of a second basin.

8. Wave generating system according to one of the preceding claims, characterized in that it comprises a plurality of water inlet mouths placed one above the other.