FR2932234A1 - Pipe device for use in open water flow for recuperating kinetic energy from sea current, has pipe whose axisymetric wall defines fluid passage channel, where wall of pipe defines divergent shape along longitudinal direction - Google Patents

Abstract

The device (10) has a pipe (11) whose axisymetric wall (12) defines a fluid passage channel (15). A capturing unit i.e. rotor, captures the part of kinetic energy from fluid i.e. water, traversing the channel. The wall has a leading edge (18) defining a fluid inlet opening (16), and a trailing edge (19) that defines a fluid outlet opening (17). The inlet opening has a section that is smaller than that of the outlet opening. The wall of the pipe defines a divergent shape along a longitudinal direction (X). Independent claims are also included for the following: (1) a kinetic energy capturing system comprising a pipe device (2) a method for locally increasing speed of a fluid flow in an open medium for recuperating the energy.

Description

PIPE DEVICE FOR DISPOSING IN A FLUID FLOW

FIELD OF THE INVENTION The invention relates to a nozzle device intended to be arranged in a fluid flow in order to locally generate an acceleration of the fluid velocity. In particular, the invention relates to a nozzle device for being arranged in an open medium in a fluid flow for recovering energy, comprising: a nozzle whose wall delimits a fluid passage channel; sensing a portion of the fluid energy flowing through the channel, wherein the wall includes a leading edge defining a fluid inlet opening and a trailing edge defining a fluid outlet opening. The invention also relates to an associated system and method. STATE OF THE ART

There are known devices for accelerating the velocity of a fluid in a confined environment, which rely on a venturi effect. For example, in the case of a fluid flowing in a pipe, the speed of this fluid can be accelerated locally by the presence of a bottleneck in application of the Bernouiili principle. Devices of this type are used in many technical fields. In particular, it has been proposed to use this type of device in systems making it possible to generate electrical energy from a naturally moving fluid (such as a marine current for example), in order to accelerate the speed of the device. fluid causing the system. WO 03/029645 A1 thus describes a system comprising turbine units immersed in the sea, each unit including a turbine and a pump coupled to the turbine. The device also includes remote generating means and a conduit for conveying fluid from each turbine unit to the generating means. The transported fluid is seawater taken by the pump. The turbine units are attached to the sea floor and are driven by the ebb and flow of the tide, so that they can not be oriented in the direction of movement of the water. This document provides that each turbine unit comprises a casing including an outer sleeve and an inner sleeve defining a fluid flow channel. The inner sleeve forms a convergent-divergent venturi. According to this document, the inner sleeve would increase the speed of the water flowing in the channel and driving the turbine. In addition, this document also indicates that the housing has a symmetrical shape in the longitudinal direction so that the turbine unit can operate in a flow and reflux situation. Other examples of nozzles intended to be arranged in a fluid flow can also be found in order to locally generate an acceleration of the fluid velocity. The effectiveness of such nozzles is limited when the nozzle is placed in an open environment. It is specified that in this text an open medium is understood to mean a medium in which a fluid (which is to be accelerated by means of a nozzle - in particular to recover its energy) circulates without being forced into the nozzle. An open medium thus corresponds to a marine or aerial flow, in which the possible limits (surface, bottom, walls, etc.) are remote from the nozzle. By far is understood here by convention distant from a distance greater than the diameter of the nozzle.

And the operation of a device venturi type in a confined environment (case of a forced fluid in a pipe) is not transposable in an open environment. It is found that in an open environment, the fluid tends to bypass the casing, so that the desired effect consisting in an acceleration of the flow driving the turbine, does not occur. More specifically, the applicant has carried out tests which have revealed that a venturi of known type for open-ended penstock catches only a stream covering a section corresponding to a fraction of the diameter of the venturi.

SUMMARY OF THE INVENTION

An object of the invention is to provide a device for locally accelerating the speed of a fluid in motion, in the case of a fluid circulating in an open medium. More precisely, the invention aims to propose a device whose performance would be greater than that of known nozzles, in particular of the venturi type. To this end, the invention proposes a nozzle device intended to be disposed in an open medium in a fluid flow for recovering energy, comprising: a nozzle whose wall delimits a fluid passage channel; means for sensing a portion of the energy of the fluid passing through the channel, wherein the wall comprises a leading edge defining a fluid inlet opening and a trailing edge defining a fluid outlet opening, characterized in that that the fluid inlet opening has a section 30 smaller than the section of the fluid outlet opening, the wall of the nozzle defining a divergent and asymmetrical shape in the longitudinal direction.

Preferred, but not limiting, aspects of such a device will be set forth later in this text. They can be improvements associated with particular benefits; The invention also relates to a system for sensing a kinetic energy of a naturally moving fluid, comprising: - a nozzle device as defined above, intended to be arranged in a fluid flow, - conversion means arranged in the channel, adapted to convert the movement of the fluid into a driving movement to drive means for pumping or compression, - pumping or compression means driven by the conversion means, the pumping or compression means being suitable withdrawing said fluid and circulating it for transport to remote storage or conversion means. The invention also relates to a method for locally increasing the speed of a fluid flow in an open medium for recovering energy, comprising: the device: a nozzle whose wall delimits a fluid passage channel; means for capturing a portion of the energy of the fluid passing through the channel, in which the wall comprises a leading edge delimiting a fluid inlet opening and a trailing edge delimiting an opening (fluid outlet, characterized in that the fluid inlet opening has a section 25 smaller than the section of the fluid outlet opening, the wall of the nozzle defining a divergent and asymmetrical shape in the longitudinal direction.

PRESENTATION OF FIGURES

Other features and advantages will become apparent from the description which follows, which is purely illustrative and nonlimiting and should be read with reference to the appended figures, in which: FIG. 1 is a diagrammatic perspective view of a device for nozzle 2 according to a first embodiment of the invention; FIG. 2 schematically shows, in longitudinal section, a nozzle device according to the first embodiment of the invention; FIG. 3 schematically represents , in longitudinal section, a nozzle device according to a second embodiment of the invention, • Figure 4 schematically shows a device for capturing a kinetic energy of a marine current, including a nozzle device, • FIGS. 5 to 7 diagrammatically represent velocity and pressure fields obtained by simulation, for a jump of 20 pressure caused by the presence of a rotor in the 400 Pascals nozzle device (the velocities are normalized to 1 representing the speed of the incident flow, and the pressures are static pressures): o figure 5: axial velocity, 25 o figure 6: radial velocity, o FIG. 7: pressure FIGS. 8 to 10 are representations similar to FIGS. 5 to 8, for a zero pressure drop at the rotor (rotor absent or inactive): FIG. 8: axial velocity, 30.degree. FIG. 9: radial velocity, FIG. 10: pressure. DESCRIPTION OF THE INVENTION

We will in this section expose features of the invention. A following section will detail some embodiments. The applicant has conducted extensive investigations to qualify the performance of various nozzle device configurations that would be placed in an open fluid (eg, water) flow, and which would include energy sensing means such as a rotor. For this purpose, the applicant has notably carried out tests on different configurations. It is recalled that knowledge acquired for forced pipe nozzles can not be transposed for nozzles operating in an open environment, as shown by first tests. These first 15 tests have indeed shown that a conventional venturi convergent-divergent type was open medium a real obstacle to the fluid, and a significant portion of fluid bypassed this obstacle instead of engaging in it. For the tests carried out, the nozzle was modeled by an axisymmetric fairing 20 with symmetry of revolution. Such a configuration is not only practical for modeling and testing - it also corresponds to a solution that can naturally be implemented. It is not required, however. The energy capturing means have in turn been represented by a pressure jump, which corresponds to a pressure drop. This pressure jump has been represented in certain figures by a line orthogonal to the direction of the current, at the location of a rotor. A central hub has also been modeled to include the hub carrying a rotor (which represents the capturing means). The pressure jump line thus joins the central hub to the wall of the nozzle. The tests notably implemented numerical simulations with FLUENT V6.2.16 software. The calculations assumed the stationary flow of a real fluid. Turbulence was modeled by an RNG model (k-epsilon). Based on the observation that the traditional convergent-divergent venturi form produced poor performance in an open environment, the five tests explored various geometrical configurations. For this purpose it was first decided to explore the influence of four shape parameters of the nozzle. These parameters are: - DR (rotor diameter) - DE (nozzle inlet diameter) 10 - DS (nozzle outlet diameter) - L (nozzle length). By varying these parameters the performances of 174 configurations have been characterized - in particular in terms of the operating flow rate and the maximum recoverable power at the rotor. Interestingly, this first phase of testing has identified two trends. Indeed, for an incident fluid flow of given characteristics it appears that: - convergent profiles (DE greater than DS) lead to lower flow rates - probably because their shape slows the fluid, 20 - divergent profiles (DS greater than DE) lead to higher flow rates. This first teaching thus made it possible to demonstrate that for a nozzle device intended to be placed in an open medium in a flow of fluid in order to recover energy from it, the fact that the fluid inlet opening has a section less than the section of the fluid outlet opening, the wall of the nozzle defining a divergent and asymmetrical shape in the longitudinal direction, allows to obtain significant flow rates. An explanation of this surprising result is that the divergent shape of the nozzle makes it possible to suck the fluid; whereas a convergent form tends to repel it. For a nozzle this feature is probably not intuitive - it has proved advantageous for a nozzle in an open environment.

This corresponds to a first aspect of the invention. The applicant then looked for ways to further improve the operation obtained. For this purpose, a configuration has been sought in which the risks of detachment of the fluid from the walls of the nozzle are minimized. For this an advantageous configuration is that the surface of the inner wall of the nozzle has a divergent shape whose angle with the longitudinal direction increases from the inlet of the nozzle to its outlet. And preferably said angle increases continuously from the inlet of the nozzle to its outlet. In this respect, according to one embodiment which has been particularly efficient, the equation of the internal profile of the nozzle for a geometry of 10 meters long for a rotor diameter of 4 m is: Y = 0.0005 X * X * X * X - 0.0072 X * X * X + 0.034 X + 2 X belonging to the interval [-1.5, 8.5] with Y the radial coordinate of the nozzle and x the longitudinal coordinate, the rotor being positioned at x = 0 . The limits of delamination appear moreover pushed back relative to the known operating regimes of the nozzles in a forced environment. In this respect it is generally accepted that a nozzle has a limit opening angle of the order of 8 degrees (this angle is that between the longitudinal direction and the chord of the surface, if any, curve ù of the diverging section of the nozzle). This means that for a nozzle whose diverging portion has an angle greater than this value the fluid may peel away from the walls, thus causing a significant loss of efficiency. In the case of nozzles in an open environment the applicant has shown that this angle was brought to a value of the order of 18 30 degrees. This could be explained by the fact that in open medium fluid flow lines having bypassed the nozzle join lines of fluid stream having passed through the nozzle, helping to keep these last laminar flow lines by sucking them. It is thus possible, and quite advantageous, to provide that the angle between two average slopes of inner surfaces of the nozzle facing each other is between 10 and 18 degrees. In a particularly advantageous configuration the angle between two average slopes of internal surfaces of the nozzle facing each other is 17 degrees. The applicant has also demonstrated another advantageous arrangement which combines with those already mentioned. Starting from divergent configurations, several forms have indeed been tested and characterized. And it has been found that it is particularly advantageous to place the energy-capturing means (typically the rotor) near an upstream edge of the nozzle intended to be placed upstream of the fluid stream. In other words, it is advantageous not to have or have only a few nozzle walls upstream of these means. In particular, it will be possible for the means for capturing a portion of the energy of the fluid passing through the channel to be at most 20% of the length of the nozzle in its longitudinal direction. The nozzle wall portion which may be disposed upstream of these means is not within the scope of the invention as a function of collecting fluid by forcing it into the nozzle, contrary to what is known in the state of the technique. On the other hand, the nozzle may comprise, between its upstream edge and the means for capturing a portion of the energy of the fluid passing through the channel, a part of the wall whose function is to direct the leading edge of the nozzle facing the current lines. of fluid to minimize fluid flow disturbances. This wall portion is thus intended to have a nose facing the current lines that are directed towards the inlet of the nozzle.

The applicant has yet identified another particularly advantageous feature. According to this characteristic, at least one zone of the wall has a bearing profile capable of creating a pressure difference between the fluid flowing along the inner surface of the wall and the fluid flowing along its outer surface, causing a depression of the fluid in the channel, the pressure of the fluid exerted on the inner wall surface being less than the pressure exerted on its outer surface. The features mentioned above can be combined. They make it possible to create particularly powerful nozzles in an open environment. The applicant thus determined that compared to a rotor in open water the performances were increased by 110%. A rotor in open water will indeed capture only 60% of the flow directed towards him (of the current vein of the same diameter as him) while a nozzle according to the invention can capture 130%. And this performance is much greater than what can produce a convergent-divergent or convergent nozzle, which in turn pushes the fluid in open water and thus captures less than 60%. It is also possible to provide two types of architecture that correspond to two types of additional improvements. According to a first type of improvement, the nozzle device comprises at least two nozzles arranged so that a first nozzle prints the fluid a first acceleration before the entry of at least a part of the fluid thus accelerated in the following nozzle. In this case the nozzles can be arranged coaxially around the same longitudinal axis. And the nozzles can in particular be arranged one inside the other, each nozzle that recovers fluid accelerated by another nozzle called first nozzle being disposed within this first nozzle. Still according to this first type of improvement, two nozzles may be arranged so that a fluid inlet opening of the first nozzle is positioned in an area of the second nozzle constituting a zone of maximum acceleration of the fluid flowing in the second nozzle And it can be expected that the device comprises several nozzles connected in series and forming a cascade. According to a second type of additional improvement, which can be combined with the first type, the device comprises, in the channel of a nozzle, elements of internal segmentation of the space whose main function is to avoid the detachment of fluid from the internal walls 10 of the nozzle. These segmentation elements allow to further open the angle of the nozzle, arriving at a limit value of about 18 degrees for each channel portion located between two walls.

EXAMPLES OF EMBODIMENTS

Figures 1 and 2 show a nozzle device 10 according to a first embodiment of the invention. The nozzle device 10 comprises a nozzle 11 formed of a wall 12 having a generally symmetrical shape of revolution, whose axis of symmetry X is intended to be oriented parallel to the direction of flow of a fluid flow. The wall 12 has an inner surface 13 and an outer surface 14. The inner surface 13 defines a channel 15 for fluid passage. The wall of the nozzle has a divergent shape. The angle between this wall and its axis of symmetry X increases continuously from its fluid inlet opening 16 to its fluid outlet opening 17. As is more specifically illustrated in Figure 2, the wall 12 has a bearing profile. In this case, the profile is defined as the contour 30 of the longitudinal section of the wall 12. The outline of the profile is shown in FIG. 2. In other words, the profile is able to create locally, at a zone level. 1 predetermined channel (suction zone), a pressure difference between fluid flowing along the inner surface 13 of the wall and the fluid flowing along the outer surface 14 of the wall. More specifically, the profile has a shape such that, in zone 1 considered, the pressure generated on the inner surface 13 (or extrados) is less than the pressure generated on the outer surface 14 (or intrados). On the one hand, this pressure difference has the effect of creating a lift force exerted on the wall 12 in the zone 1. However, because the wall 12 is symmetrical of revolution, the resultant of all the lift forces exerted on the wall 12 is parallel to the longitudinal direction X of the nozzle 11. This depression in the zone 1 contributes to the suction of the fluid in the channel 15. The channel extends between an opening 16 of the fluid inlet and a fluid outlet opening 17. The wall 12 comprises a leading edge 18 defining the circularly shaped fluid inlet opening 16 and a trailing edge 19 delimiting the circularly shaped fluid outlet opening 17. The wall 12 is oriented so that the fluid inlet opening 16 has a smaller diameter than the diameter of the fluid outlet opening 17.

The wall 12 extends in a general direction inclined relative to the longitudinal axis X of the nozzle 11 which corresponds to the direction of flow of the fluid. The bearing profile is oriented divergently with respect to the X direction in the flow direction of the fluid. This has the effect that when the nozzle device 10 is placed in a fluid stream, the fluid is strongly accelerated in the suction zone 1 of the channel 15 and the fluid flow is important in this zone. FIG. 3 represents a nozzle device 20 according to a second embodiment of the invention. The nozzle device 20 comprises a first nozzle 11 and a second nozzle 21 associated in series. The first nozzle 11 extends partly inside the second nozzle 21. The first nozzle 11 conforms to the nozzle 11 of Figures 1 and 2.

Similar to the first nozzle 11, the second nozzle 21 comprises a wall 22 having an inner surface 23 and an outer surface 24, a channel 25, a fluid inlet opening 26, a fluid outlet opening 27, a leading edge 28 and a trailing edge 29.

The wall 22 has a bearing profile, capable of locally creating, at a predetermined zone 2 of the channel (suction zone), a pressure difference between fluid flowing along the inner surface 23 of the wall and fluid flowing along the outer surface 24 of the wall.

When the nozzle 21 is placed in a stream of fluid, the fluid is greatly accelerated in the zone 2 of the channel 25 and the flow of fluid is important in this zone. As illustrated in FIG. 3, the nozzles 11 and 21 are arranged so that their axes X coincide and so that the leading edge 18 of the first nozzle 11 is positioned in the suction zone 2 of FIG. the second nozzle 21. With such an arrangement, the fluid enters first into the second nozzle 21 and is accelerated under the effect of the suction occurring in the suction zone 2. It is in this zone 2, in which the speed of the fluid is maximum, that the first nozzle 11 takes part of the fluid. The fluid enters secondly into the first nozzle 11 and is again accelerated by the suction occurring in the suction zone 1. A cascade may be formed by thus mounting several nozzles in series. The mounting of the nozzles is cascade can multiply several times the speed of the fluid flowing in the device. Figure 4 schematically shows a system for capturing kinetic energy of a marine current, including a nozzle device according to the invention. The system comprises a first portion 100 immersed in sea water M and a second portion 200 located on the ground S, for example installed on one side, away from the submerged portion. The device also comprises a pressurized fluid transport network 300 extending between the first part 100 and the second part 200. In the embodiment illustrated in FIG. 4, the immersed part 100 comprises two receiving units 110 held in a fixed position relative to each other by mechanical connection means 130. Each unit 110 comprises a propeller 111 rotatably mounted relative to the conversion unit. Each propeller 111 is adapted to be rotated by the movement of the current (whose direction C is symbolized by arrows). The propellers 111 have a pitch inverted relative to each other so that they generate on the pair formed of the two units 110 couples that cancel each other. Each unit 110 also comprises a pump 112, such as a multicellular centrifugal pump, driven by the associated propeller 111.

Each pump 112 has a fluid inlet 113, and a fluid outlet 114. The fluid outlets 114 are connected to the fluid transport network 300. When it is driven by the propeller 111, the pump 112 is able to collect seawater via the fluid inlet 113 and to inject the seawater under pressure into the transport network 300 via the outlet 114. The seawater is injected by the pump at a high pressure, for example up to 100 bar. Seawater is taken directly from the surrounding environment. The pressurized seawater is conveyed via line 300 to the portion 200 of the system located on the ground. Each unit 110 also comprises a respective nozzle device 10 associated with the propeller 111. The nozzle device 10 is disposed in the fluid flow C. Each nozzle device 11 has the function of locally accelerating the speed of the fluid. sea water driving the propeller. For this purpose, the helix 111 is disposed precisely in the suction zone 1 of the nozzle 11 (see FIGS. 1 and 2).

The pressure jump (denoted AP) generated by the presence of the helix 111 must remain low enough not to prevent the fluid from entering the channel 15. In a variant of the system, the nozzle device associated with each propeller is a device comprising a plurality of cascaded nozzles, according to the embodiment of Figure 2. In such a mounting, the propeller 111 is disposed in the suction zone 1 of the first nozzle 11 (see Figure 3). The second part 200 of the system, located on the ground, comprises storage means 210 located in height, conversion means 220 located at a lower altitude, and a connecting conduit 230 extending between the storage means 210 and the means The storage means 210 includes a reservoir 211 disposed in height (at a height h) from sea level. The reservoir 211 comprises a fluid inlet 212 and a fluid outlet 213. The inlet fluid 212 is connected to the transport conduit 230. Thus, the tank 210 receives seawater which has been conveyed by the transport network 300 from the immersed part 100 of the system. The storage at the height of the fluid makes it possible to store the energy recovered by the system in the form of potential energy. The fluid outlet 213 is connected to the connecting pipe 230. The connecting pipe 230 makes it possible to route seawater from the tank 211 to the conversion means 220 on demand. The conversion means 220 comprise a turbine 221 adapted to be rotated by seawater from the reservoir 211 and an electric generator 222 coupled to the turbine 221, able to convert the rotational movement of the turbine 221 into electrical energy to generate an electric current . Appropriate regulation of the turbine 221 makes it possible to obtain a constant speed of rotation of the turbine. Since the electric generator 222 is driven at a constant speed, it produces an electric current of stable frequency (despite the variations in the speed of the current and the rotational speed variations of the helix 121).

The fluid transport network 300 comprises first conduits 311 connected to the fluid outlets 114 of the receiving units 110. The network 300 also comprises a second duct 312 connected to the first ducts 314 and making it possible to convey the fluid under pressure from the units 110 to the 200 part located on the floor of the system. Finally, the network 300 comprises a third duct 313 and a fourth duct 314 connected to the second duct 312. The third duct 313 makes it possible to convey the fluid under pressure to the tank 211. The fourth duct 314 makes it possible to convey the fluid under pressure directly up to the turbine 221. The third conduit 313 and the fourth conduit 314 are connected to the second conduit 312 via a first valve 315. The first valve 315 is able to be controlled to selectively connect the second conduit 312 to the third conduit 313 or fourth conduit 314. In other words, the first valve 315 can convey the fluid under pressure selectively to the reservoir 211 or directly to the turbine 221 without passing through the reservoir. Similarly, the fourth conduit 314 is connected to the connecting conduit 230 via a second valve 316. The second valve 316 is controllable to selectively withdraw fluid from the reservoir 211 or directly from the units 110 without passing through the reservoir, to supply the turbine 221. The pressurized fluid generated by the units 110 is either sent directly to the turbine 221, or stored for later use.

The control of the valves 315 and 316 makes it possible to regulate the flow of fluid supplying the turbine 221, in order to obtain the most stable flow rate possible. The fluid used to feed the turbine 221 is discharged to the sea via a discharge conduit 231.

EXAMPLES OF APPLICATION In FIG. 2, the nozzle device 10 has the following geometric parameters:

DR Diameter of the propeller (rotor)

LN Pump housing length (aerial platform)

DN Diameter of pump housing (nacelle)

L Length of the nozzle

Diameter of inlet of the nozzle

DS Nozzle outlet diameter The output of the nozzle device is defined as follows: Piper II = PBnull 0 Q • AP 1 = 05p U3 n R2 where

where is the efficiency of the tuyere, the pipectuyère is the pressure in the suction zone in an infinite flow, PBenouilli is the pressure that would be obtained in the suction zone in a confined flow,

Q is the flow of fluid in the suction zone, AP is the pressure jump created by the presence of the helix in the suction zone,

P is the density of the fluid, U is the velocity of the fluid (marine current), R is the internal radius of the nozzle in the suction zone. 17 Subsequently, we assume: U = 1 m / s (meter per second), DR = 4 m (meters), LN = 2 m (meters), DN = 0.6 m (meters), p = 1000 kg / m3 (kilograms per cubic meter). The results of calculating the maximum recoverable power obtained by numerical simulation are shown in Table 1. FIGS. 5, 6 and 7 respectively represent diagrammatically axial velocity, radial velocity and pressure fields for a geometry (length L = 10 m, opening angle = 17 degrees), for a jump of energy AP = 400 Pascals. FIGS. 8, 9 and 10 respectively show diagrammatically axial velocity, radial velocity and pressure fields for a geometry (length L = 10 m, opening angle = 17 degrees), for an energy jump AP = O. The use of a suitable nozzle device (in which L = 5x DR) achieves about 210% of the power of a propeller-pump unit without a nozzle. In comparison, on a typical wind turbine study, we arrived at a yield of about 0.477. For the helix-pump unit without nozzle it is 0.600 and with a suitable nozzle it goes to 1.300.

Length Angle Power Fluid velocity Recoverable opening nozzle return flow (meters / seconds) 11 L (degrees) (watts) pressure to the propeller (meters) Op (Pascals) 3.5 15 5750 1.14 400 0.92 17 5700 1.13 400 0.91 18 6490 1.29 400 1.03 19 6720 1.19 450 1.07 20 6640 1.32 400 1.06 5.0 14 6260 1.25 400 1, 00 16 6730 1.34 400 1.07 17 6930 1.23 450 1.10 19 6880 1.37 400 1.10 10.0 11 6260 1.25 400 1.00 13 6700 1.33 400 1.07 15 7410 1.48 400 1.18 17 7530 1.50 400 1.20 19 7520 1.50 400 1.20 20.0 13 8060 1.43 450 1.28 17 8140 1.62 400 1.30 19 8100 1 , 61,400 1.29 50.0 11 8500 1.69 400 1.35 13 8750 1.74 400 1.39 15 8710 1.73 400 1.38 17 8650 1.72 400 1.37 Table 1 - Recoverable Power maximum for different values of nozzle length (L) and nozzle opening angle.

Claims (22)

REVENDICATIONS1. A nozzle device (10, 20) for being arranged in an open medium in a fluid flow (C) for recovering energy, comprising: o a nozzle (11, 21) whose wall (12, 22) delimits a channel (15, 25) for fluid passage o means (111) for sensing a portion of the energy of the fluid passing through the channel, wherein the wall comprises a leading edge (18, 28) defining an opening ( 16, 26) and a trailing edge (19, 29) delimiting a fluid outlet opening (17, 27), characterized in that the fluid inlet opening has a lower section than the section of the fluid outlet opening, the wall of the nozzle defining a divergent shape in the longitudinal direction (X). 2. Device according to the preceding claim characterized in that the surface of the inner wall of the nozzle has a divergent shape whose angle with the longitudinal direction (X) increases from the inlet of the nozzle to its outlet. 3. Device according to the preceding claim characterized in that said angle increases continuously from the inlet of the nozzle to its outlet. 4. Device according to one of the preceding claims characterized in that the angle between two average slopes of inner surfaces of the nozzle facing each other is between 10 and 18 degrees. 5. Device according to the preceding claim characterized in that the angle between two average slopes of internal surfaces of the nozzle facing each other is 17 degrees. 6. Device according to one of the preceding claims characterized in that the wall of the nozzle is axisymmetric. 7. Device according to one of the preceding claims characterized in that the means (111) for capturing a portion of the energy of the fluid passing through the channel comprises a rotor. 8. Device according to one of the preceding claims characterized in that the means (111) for capturing a portion of the energy of the fluid passing through the channel are located near an upstream edge of the nozzle to be placed towards the upstream of the fluid stream. 9. Device according to the preceding claim characterized in that the means (111) for capturing a portion of the energy of the fluid passing through the channel are located at most 20% of the length of the nozzle in its longitudinal direction. 10. Device according to one of the two preceding claims characterized in that the nozzle comprises between its upstream edge and the means (111) for capturing a portion of the energy of the fluid passing through the channel wall portion whose function is to directing the leading edge of the nozzle facing the fluid flow lines to minimize fluid flow disturbances. 11. Device according to one of the two preceding claims characterized in that at least one zone of the wall has a bearing profile capable of creating a pressure difference between the fluid flowing along the inner surface of the wall and the fluid flowing along its outer surface (14, 24), causing apressure of the fluid in the channel, the fluid pressure exerted on the inner wall surface (13, 23) being less than the operating pressure on its outer surface (14, 24). 12. Device according to one of the preceding claims characterized in that it comprises at least two nozzles arranged so that a first nozzle prints the fluid a first acceleration before the entry of at least a portion of the fluid and accelerated in the next nozzle. 13. Device according to the preceding claim characterized in that the nozzles are arranged coaxially around the same longitudinal axis (X). 14. Device according to one of the two preceding claims characterized in that the nozzles are arranged one inside the other, each nozzle which recovers fluid accelerated by another nozzle said first nozzle being disposed at the interior of this first nozzle. 15. Device according to one of the three preceding claims wherein two nozzles are arranged so that a fluid inlet opening (16) of the first nozzle (11) is positioned in an area (2) of the second nozzle (21) constituting a zone of maximum acceleration of the fluid flowing in the second nozzle. 16. Device according to one of the four preceding claims comprising several nozzles connected in series and forming a cascade. 17. Device according to one of the preceding claims characterized in that it comprises in the channel of a nozzle of the internal spacesegmenting elements of the space having the main function of avoiding fluid separation on the inner walls of the nozzle. 18. Device according to one of the preceding claims, wherein the wall (12, 22) has a symmetrical shape of revolution. A system for sensing kinetic energy of a naturally moving fluid, comprising: a nozzle device (10, 20) according to one of the preceding claims, intended to be arranged in a fluid flow (C), • conversion means (111) arranged in the channel (15), able to convert the movement of the fluid into a movement driving means for driving pumping or compression means (112); pumping or compression means (112) driven by the converting means (111), the pumping or compression means (112) being adapted to withdrawing and circulating said fluid for transport to remote storage (210) or conversion (220) means. Method for locally increasing the velocity of a fluid flow (C) in an open medium to recover energy, comprising, the device: - a nozzle (11, 21) whose wall (12, 22) defines a channel (15, 25) for fluid passage - means (111) for sensing a portion of the energy of the fluid passing through the channel, wherein the wall comprises a leading edge (18, 28) delimiting a fluid inlet opening (16, 26) and a trailing edge (19, 29) delimiting a fluid outlet opening (17, 27), characterized in that the fluid inlet opening has a section less than the section of the fluid outlet opening, the nozzle wall defining a divergent and asymmetrical shape in the longitudinal direction (X).