EP3235719A1 - Lift generator device, corresponding wind-powered propeller, and corresponding propulsion installation. - Google Patents

Abstract

The invention relates to a lift-generating device comprising a hollow body (1) having two opposite walls (11, 12) with an intrados and an extrados, said extrados and intrados walls being shaped so that the body has a camber line in cross-section. whose arrow is at least 20% of the rope. Said upper wall (12) has openings (121) communicating inside said body. The device also comprises a system (3) for limiting boundary layer separation cooperating with said openings. The invention also relates to a propulsion installation comprising such a propellant.

Description

FIELD OF THE INVENTION

The present invention generally relates to thrusters for placement in a moving fluid to provide lift.

PRIOR ART

The regulation requires manufacturers of large merchant ships to reduce their CO2 emissions by 30% by 2025. As a result, partial alternatives to the diesel engines of these vessels are sought, particularly on the side of wind engines.

The document FR2847009 discloses a wind propulsion unit which comprises an elongate hollow body, suction zones provided along the peripheral wall of the hollow body and associated suction means. The suction at the peripheral wall of the thruster limits the detachment of the flow relative to the wall of the propellant.

However, it can be seen that with such a wind thruster known from the state of the art, the energy required for suction is large compared to the propulsion energy which is restored by the propellant.

The French patent application filed under the number FR1500931 , and not yet published, proposes a wind thruster whose performance is improved compared to that proposed in the document FR2847009 . Nevertheless, the wind propulsion proposed in the French patent application filed under the number FR15 00931 remains complex. Indeed, in order to be able to produce a lift force directed to one side or the other of the boat, the wind thruster uses a complex system of movable flap and movable suction chamber, so as to be able to modify the shape of the Wind thruster and change suction area depending on which side the fluid comes from. This complex system is expensive and requires maintenance.

The object of the present invention is to propose a new wind thruster and / or a new lift-generating device from which said thruster is formed, making it possible to overcome all or some of the problems described above.

SUMMARY OF THE INVENTION

• configuré pour aspirer de l'air sélectivement à travers la première ou la deuxième chambre, par, respectivement, la première ou la deuxième ouverture, et/ou
• configuré pour souffler de l'air sélectivement depuis la première ou la deuxième chambre à travers la première ou la deuxième ouverture, tangentiellement à ladite paroi extrados en direction d'un bord de liaison entre les parois intrados et extrados,

caractérisé en ce que le corps creux est sensiblement symétrique selon un plan de symétrie qui est perpendiculaire à la ligne de corde joignant les bords de liaison entre lesdites parois intrados et extrados, et qui coupe ladite corde sensiblement en son milieu,
et en ce que les deux ouvertures sont positionnées sensiblement symétriquement par rapport audit plan de symétrie.For this purpose, the subject of the invention is a device, called a lift generator device, intended to be placed in a moving fluid, such as air, in order to produce a lift force,
the device comprising a hollow body elongate along an axis, said body having two opposite walls, called respectively intrados and extrados,
said extrados and intrados walls being shaped so that the body has in cross section a camber line whose deflection is at least equal to 20% of the length of the rope joining the connecting edges between said intrados and extrados walls,
the extrados wall having an opening adapted to communicate with a first chamber located within said body and an opening communicating with a second chamber located within said body, the device comprising a boundary layer detachment limitation system:

• configured to suck air selectively through the first or second chamber, respectively, by the first or second opening, and / or
• configured to blow air selectively from the first or second chamber through the first or second opening, tangentially to said extrados wall toward a connecting edge between the intrados and extrados walls,

characterized in that the hollow body is substantially symmetrical about a plane of symmetry which is perpendicular to the line of rope joining the connecting edges between said intrados and extrados walls, and which cuts said rope substantially in its middle,
and in that the two openings are positioned substantially symmetrically with respect to said plane of symmetry.

The line of curvature ("mean line" in English) is defined as being the curve joining the leading edge to the trailing edge which is equidistant from the extrados and the intrados. The leading edge and the trailing edge correspond to the edges farthest from the plane of symmetry, or to the lateral extremities of greater curvature. The arrow of the line of camber is also called camber. The arrow of the camber line is defined by the distance between the top (S) of the camber line (LCBR1) (as shown in the example of Figures 5 and 6 ), and the line (LC1) which connects the ends of the line of camber. This line corresponds here to the rope.

The curvature of the extrados wall is greater than that of the intrados wall.

As stated above, the arrow of the camber line is at least 20% of the length of the rope and perhaps for example of the order of 50% of the length of the rope.

According to a particular embodiment, said upper and lower walls are respectively convex and concave. The convexity of the extrados wall is defined by reference to a person located outside the body and looking directly at said extrados wall. Similarly the concavity of the wall intrados is defined by reference to a person located outside the body and looking directly at said intrados wall.

The openings are formed on the wall of greater camber (extrados wall), but additional openings could also be made on the wall of less strong arch (intrados)

Thanks to the plane of symmetry of said body as defined above, the flow around the profile and the lift are substantially identical depending on whether one or the other of the connecting edges is used as a leading edge or edge leak.

Such a design of the device according to the invention makes it possible to invert the trailing edge and leading edge functions of the opposite connecting edges of the hollow body, without this altering the aerodynamic performance of the device. The device thus makes it possible to be exempt from a complex mechanical system that makes it possible to reverse the camber.

Further, such a configuration of the two apertures and the boundary layer detachment limitation system selectively suck and / or blow selectively at the apertures, thereby creating substantially the same delamination limiting effect as one or the other of the connecting edges is the leading edge.

In other words, the thruster comprises a body extending along an axis and having in cross section a generally arched shape whose opposite ends are tapered.

Preferably, said openings forming suction and / or blowing zones are arranged symmetrically with respect to said plane of symmetry. The distribution of the openings on either side of the plane of symmetry allows suction on one side or the other of the body depending on whether the flow of fluid is incident on one side or the other of the axis of symmetry, in order to obtain the desired thrust and limit the detachment of the fluid relative to the wall of the thruster.

The device is intended to be placed in a moving fluid (or conversely) of direction transverse to the longitudinal axis of the hollow body.

The strong camber of the profile associated with the suction of one of the zones of the extrados wall makes it possible to produce a very high lift per unit area by preventing delamination of the boundary layer of the wall of said body.

Such a profile of the body of the device allows compared to the known devices of the state of the art can be presented to the fluid, indifferently, one or the other of its ends which then acts as a leading edge, while that the other end of the profile of the body forms trailing edge, while obtaining a significant lift force.

The device has the advantage of being able, by simple rotation about the longitudinal axis of the body, to be oriented relative to the incident fluid to produce a transverse force with respect to the direction of said fluid. Said lift force can then be oriented on one side or the other of the direction of the fluid, without it being necessary to modify the aerodynamic shape of the device by actuating moving parts, such as a flap like that. is the case of certain devices known from the state of the art.

Thus, as detailed below, in the case of a wind propulsion unit, such a design of the device makes it possible to create a force transverse to the direction of the wind that the moving object receives, for example a boat, and oriented in one direction. which depends on the side by which said moving object takes the wind.

The fact of being able to produce a transverse force with respect to the direction of the fluid in which the device is placed, oriented optionally on one side or the other of said direction of the fluid is particularly advantageous for certain applications such as propulsion by the wind of a ship.

As explained below, it is possible according to one embodiment to separate into two parts, or compartments, the interior of the device with a transverse bulkhead, preferably perpendicular to the string line, and substantially parallel to the body axis. It is then possible to set up a suction and / or blowing means for each compartment. Advantageously, said wall is positioned equidistant from both ends of the profile.

Such profiles have the advantage of possessing their naturally arched shape and their reduced thickness of better aerodynamic performance than the thick shutter profile of known devices, which makes it possible to reduce the suction power required to reach a lift or lift. given strength.

According to an advantageous characteristic of the invention, the intrados and extrados walls being connected to one another, the connecting edges between said walls are rounded to form a leading edge and a trailing edge in the direction of the fluid. moving.

• un premier système d'aspiration et/ou de soufflage communiquant avec la première ouverture et agencé pour mettre en dépression la première chambre ou pour souffler de l'air depuis la première chambre à travers ladite première ouverture, tangentiellement à ladite paroi extrados en direction de la zone de liaison entre les parois intrados et extrados qui est située du côté opposé à la première ouverture,
• un deuxième système d'aspiration et/ou de soufflage communiquant avec la deuxième ouverture et agencé pour mettre en dépression la deuxième chambre ou pour souffler de l'air depuis la deuxième chambre à travers ladite deuxième ouverture, tangentiellement à ladite paroi extrados en direction de la zone de liaison entre les parois intrados et extrados qui est située du côté opposé à la deuxième ouverture,

le premier et le deuxième systèmes d'aspiration et/ou de soufflage pouvant être distincts ou communs en tout ou partie.According to an advantageous characteristic of the invention, said boundary layer detachment limiting system comprises:

• a first suction and / or blowing system communicating with the first opening and arranged to depressurize the first chamber or to blow air from the first chamber through said first opening, tangentially to said extrados wall in the direction of the zone of connection between the intrados and extrados walls which is situated on the opposite side to the first opening,
• a second suction and / or blowing system communicating with the second opening and arranged to depressurize the second chamber or to blow air from the second chamber through said second opening, tangentially to said extrados wall in the direction of the zone of connection between the intrados and extrados walls which is located on the opposite side to the second opening,

the first and second suction systems and / or blowing may be separate or common in whole or in part.

According to an advantageous characteristic of the invention, said boundary layer detachment limiting system comprises at least a portion located outside the body and connected to the openings by conduits.

According to an advantageous characteristic of the invention, said body having a separation wall which separates the interior of the body so as to delimit said first and second chambers, said separation wall extends substantially transversely, preferably orthogonally, to said line. of rope.

According to an advantageous characteristic of the invention, said boundary layer detachment limiting system being configured to suck air selectively through the first or second chamber, respectively, by the first or second opening, said limiting boundary layer delamination comprises a discharge outlet oriented in a direction tangential to the extrados wall, and preferably orthogonal to the axis of the hollow body, to the connecting edge located downstream of the direction of the moving fluid in which the device is placed.

According to an advantageous characteristic of the invention, said device comprises profiled elements extending parallel to the axis of the body of the device and positioned in a fixed manner near the wall of the body of the device.

These shaped members are configured to improve flow by reducing peeling at the ends of the profile.

According to an advantageous characteristic of the invention, the boundary layer delamination limitation system comprises at least one centrifugal fan, preferably a centrifugal fan for each opening. According to different embodiments, the fan can operate in suction or blowing.

The invention also relates to an installation comprising a device as described above, characterized in that the installation comprises means for orienting the device for moving the device from a first position to a second distinct position by pivoting. the device about an axis parallel, preferably coincidental, with the axis of said body of the device.

Advantageously, the orientation means are configured to be able to rotate the device in an angular range of [- 90 °; + 90 °] in relation to the horizontal direction perpendicular to the longitudinal axis of the boat.

In other words, the orientation means can be configured to be able to rotate the device in an angular range such that the angle that the mediator of the rope of the profile with the longitudinal axis of the boat can vary from -90 ° to + 90 °.

The invention also relates to a preferably Aeolian thruster comprising several devices as described above, characterized in that said devices are superimposed. The superimposed devices thus form the different stages of the wind thruster.

Advantageously, the suction and / or blowing means of the different stages are distinct from each other so that they are capable of sucking and / or blowing on one stage without sucking and / or blowing on the others.

The separation of the suction and / or blowing zones along the thruster makes it possible to homogenize the suction along the body of the thruster.

In addition, such a separation of the thruster into different superposed modules with independent operation makes it possible to activate the suction and / or blowing means of only a part of the modules, for example of the lowest module, according to the power of the wind .

Of course it is also possible to make a thruster comprising a single lift generator device.

The invention also relates to a boat which comprises an installation as described above, characterized in that said installation is mounted on the deck or a superstructure of said boat.

A wind propeller mounted on the deck of a boat (or ship) achieves a greater aerodynamic thrust per unit area than a rigid sail or wing, while occupying limited space on the deck of the ship.

The thruster can thus be oriented according to the direction of the wind to obtain a suitable thrust.

Advantageously, said boat comprises a system for articulating the device relative to the base, said articulation system being configured to allow the device to be moved between an erected position, in which, in the fixed state from the base to the deck of the ship, it extends perpendicular to the deck of the boat, and a tilted position, in which, at the fixed state of the base at deck of the boat, the device extends substantially parallel to the deck of the boat.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 est une vue de dessus d'un bateau équipé d'un propulseur selon un mode de réalisation de l'invention, dans une configuration selon laquelle ledit bateau reçoit le vent par tribord ;
• la figure 2 est une vue de dessus d'un bateau équipé d'un propulseur selon un mode de réalisation de l'invention, dans une configuration selon laquelle ledit bateau reçoit le vent par bâbord ;
• la figure 3 est une vue en perspective avant d'un dispositif de génération de portance selon l'invention, utilisé par exemple pour former le propulseur de la figure 1 ou 2 ;
• la figure 4 est une vue en perspective arrière d'un propulseur éolien comprenant plusieurs dispositifs, encore appelés modules, superposés, par exemple conformes ou similaires au dispositif illustré à la figure 3 ;
• la figure 5 est une vue en coupe transversale du corps creux du dispositif selon un mode de réalisation donné, dans une configuration selon laquelle ledit corps reçoit le vent d'un côté, et selon laquelle le fluide est aspiré par la deuxième chambre d'aspiration, l'écoulement de fluide étant schématisé ;
• la figure 6 est une vue en coupe transversale du corps creux du dispositif selon un mode de réalisation donné, dans une configuration selon laquelle ledit corps reçoit le vent de l'autre côté par rapport à la figure 5, et selon laquelle le fluide est aspiré par la première chambre d'aspiration, l'écoulement de fluide étant schématisé.

Other features and advantages of the invention will become apparent from the description which follows, which is purely illustrative and nonlimiting and should be read with reference to the accompanying drawings, in which:

• the figure 1 is a top view of a boat equipped with a thruster according to one embodiment of the invention, in a configuration according to which said boat receives the wind from the starboard side;
• the figure 2 is a top view of a boat equipped with a thruster according to one embodiment of the invention, in a configuration according to which said boat receives the wind on the port side;
• the figure 3 is a front perspective view of a lift generation device according to the invention, used for example to form the propellant of the figure 1 or 2 ;
• the figure 4 is a rear perspective view of a wind propulsion unit comprising several devices, also called modules, superimposed, for example conforming or similar to the device illustrated in FIG. figure 3 ;
• the figure 5 is a cross-sectional view of the hollow body of the device according to a given embodiment, in a configuration according to which said body receives the wind on one side, and according to which the fluid is sucked by the second suction chamber; fluid flow being schematized;
• the figure 6 is a cross-sectional view of the hollow body of the device according to a given embodiment, in a configuration according to which said body receives the wind on the other side relative to the figure 5 and wherein the fluid is sucked by the first suction chamber, the fluid flow being schematized.

DETAILED DESCRIPTION

Referring to the figures and as recalled above, the invention relates to a lift generator device, also called a propulsion device, and a corresponding preferably aeolian propellant intended to be placed in a fluid flow in motion to produce lift. It can be provided that the thruster comprises a single lift generating device or a plurality of superposed lift generating devices as illustrated in FIG. figure 4 .

The lift force can be used to propel a moving body such as a boat. Thus, according to a preferred use, the thruster is of the aeolian type and is mounted on a boat so that the flow of air flows around said wind thruster to generate a propulsive force.

The principle of lift, well known to those skilled in the art, is described in particular in the document EP0055638 .

In the example illustrated in the figures, the wind propulsion unit comprises several propulsion devices that are superimposed. Thus, as illustrated more particularly in figure 4 , the wind propulsion unit comprises a propulsion device 102 high, an intermediate propulsion device 101 and a propulsion device 100 low.

In operation, the longitudinal axis A1 of the thruster is substantially vertical.

Each propulsion device, also called module, comprises an elongate hollow body. As illustrated in figure 1 , the hollow body comprises a peripheral wall whose profile, corresponding to a section of the hollow body in a plane transverse to the longitudinal axis A1 of said hollow body, has a plane of symmetry P1.

In other words, the body has a plane of symmetry perpendicular to the line LC1 rope that joins the two ends 111, 112 of the profile and cut it in the middle. The plane of symmetry P1 passes through said axis A1. Thus the flow of the fluid and the lift are substantially identical depending on whether one or other of the ends formed by the connecting zones 111, 112 form the leading edge or the trailing edge of the profile.

When the thruster comprises a plurality of superposed devices as illustrated in FIG. figure 4 these devices are of identical design or similar to each other so that they are called modules thereafter. Naturally, the characteristics described below for the modules also apply to a single lift-generating device in the case where the wind propulsion unit comprises a single device generating a lift.

The modules are superimposed along their longitudinal axis so that the longitudinal axis of the thruster is parallel or coincident with the longitudinal axis of each module. In other words, the longitudinal axis of the thruster corresponds to the axis in which the modules are superimposed. In addition, the modules are superimposed coaxially. In other words, the longitudinal axis of the thruster corresponds to the longitudinal axis of each module.

The body of each module has two opposite walls 11, 12, respectively called intrados and extrados. The extrados and intrados walls are assembled to one another. In operation, with reference to the direction of movement of the propelled object, the wall 12 is oriented on the front side of the propelled object and the wall 11 is oriented on the rear side of said propelled object.

Said extrados and intrados walls are shaped so that the body has in cross section a camber line whose arrow is at least equal to 20% of the length of the rope joining the connecting edges between said intrados and extrados walls.

In the example illustrated in the figures, said extrados and intrados walls are respectively concave (hollow) and convex (convex) by reference to a person located outside the thruster which looks directly at these walls. The curvature of the extrados wall is greater than that of the intrados wall. The most curved wall (arched) has the function of extrados and the wall the least curved (arched) the function of intrados. The two walls meet at both ends 111, 112 of the profile. The line of curvature LCBR1 is schematized on the Figures 5 and 6 .

The intrados 11 and extrados 12 walls are connected to each other. The connecting edges 111, 112 corresponding between said walls are rounded to form a leading edge and a trailing edge in the direction of the fluid in motion. In other words, the connecting edges 111, 112 are profiled to act as leading edge or trailing edge in the direction V. The leading edge is the edge that receives the fluid and the trailing edge is the edge where the fluid leaves the body.

In particular, the two ends 111, 112 of the profile have the same tapered shape which allows, in the direction V of the fluid relative to the profile, that one or other of the ends act as trailing edge ensuring the function separation of the fluid flows between the intrados wall and the extrados wall. The opposite end of the profile then acts as a leading edge with respect to the fluid.

Said upper wall 12 has, on one side of the plane of symmetry P1, an opening 121 adapted to communicate with a first chamber 21 of said body and, on the other side of the plane of symmetry P1, an opening 122 communicating with a second chamber 22 of said body. Preferably, the two openings 121, 122 are provided with grids formed in the wall 12 of each module.

In the example illustrated in the figures, said body has a separation wall 13 which separates the interior of the body so as to delimit said first and second chambers 21, 22. Said partition wall 13 extends substantially transversely, preferably orthogonally, to the average plane of each of the walls 11, 12 intrados and extrados.

Said partition wall 13 may be formed by a watertight partition extending parallel to the plane P1, that is to say transversely to the line of rope joining the ends of the body.

Said chambers can be put under vacuum or overpressure independently of one another so as to be able to suck or blow selectively by one or the other of the openings.

The thruster comprises a system 3 for limiting boundary layer separation.

According to one embodiment, said boundary layer detachment limiting system 3 is configured to suck air selectively through first or second chamber 21, 22, respectively, by the first or second opening 121, 122 Advantageously and as illustrated in the figure 5 or at figure 6 , it is planned to suck by the fan further downstream of the wind direction V. Thus, the system makes it possible to draw the fluid at the surface of the body on the extrados side of the profile in order to limit the separation of the boundary layer of flow with respect to said body wall.

According to an embodiment that is combinable with the or alternatively of the embodiment relating to suction, said boundary layer separation limitation system 3 can be configured to blow air selectively from the first or second chamber 21, 22, through the first or second opening 121, 122, tangentially to said extrados wall 12. Advantageously, the blowing is performed towards the connecting edge 111 or 112 which is the most downstream of the wind direction V.

According to a combined configuration of said embodiments presented above, it is then possible to suck through an opening and blow through the other opening. In particular, it can be expected to suck through the fan further downstream of the wind direction and blow through the fan upstream, towards the connecting edge most downstream of the wind direction V.

According to the embodiments of the Figures 1 to 3 said boundary layer detachment limiting system 3 comprises first and second suction systems 31, 32. In other words, as illustrated in the figures, each chamber 121, 122 is provided with its own system 31, 32 suction. Each suction system 31, 32 preferably comprises a centrifugal fan with a vertical axis. The axis of rotation of the fan is parallel to the longitudinal axis of the hollow body.

It can be provided that the discharge outlet of each suction system 31, 32 is oriented in a direction tangential to the extrados wall and to the end of the profile closest to said suction system.

According to the embodiment illustrated in figure 4 for which the thruster comprises several superposed modules, the chambers of the modules are devoid of fluid communication means between them. Thus each floor formed by a module includes its own rooms that do not communicate with the rooms of other modules.

Advantageously, said thruster also comprises a control unit configured to control the systems 31, 32 for suction and / or blowing depending on the direction and wind speed. It can be provided that the thruster is equipped with wind data detection means, in particular its direction and its speed, said detection means then being configured to communicate these data to the control unit.

The control unit comprises electronic processing means and / or computer which include for example a microcontroller or a microprocessor.

When it is specified that the control unit is configured to perform a given operation, it means that the corresponding electronic processing means and / or computer comprises computer instructions and corresponding means of execution that make it possible to perform said operation.

Advantageously, the control unit is also configured to control said systems 31, 32 for suction and / or blowing each of the modules 100, 101, 102, for example as a function of data relating to the air flow V incident on the thruster 1.

According to an aspect not illustrated in the figures, the wind propulsion unit is equipped with a support base of said thruster which is fixable on the deck of a boat 9.

The figures 1 and 2 illustrate two different positions of the booster mounted on the deck of a boat 9. Said installation thus comprises means for orientation or pivoting drive means (not shown) of the thruster about an axis of rotation parallel to its longitudinal axis A1. The thruster can thus be oriented according to the direction of the wind to vary the direction of the thrust force according to the direction of the wind.

In the example illustrated in the figures, said orientation means enable the device to be oriented on a given angular sector at least so that the line of rope LC1 can form with the direction of the wind V a given angle, preferably approximately 25 °, and that the intrados wall 11 (the least arched) is oriented towards the left (port) of the propelled object when the direction of the wind V comes from the right (starboard) and vice versa.

Thus, as illustrated in figure 1 , in the case where the direction of the wind V is incident on the starboard thruster, the device is positioned so as to orient the intrados wall towards the port side and the rear of the boat, and to form an angle ALPHA, preferably of the order of 25 ° between the line of rope LC1 and the direction of the wind V. One thus obtains a force F the forward and the starboard side of the boat.

Conversely, as illustrated in figure 2 in the case where the direction of the wind V is incident on the thruster on the port side, the device is positioned so as to orient the intrados wall towards the starboard side and the rear of the boat and to form an ALPHA angle, preferably order of -25 ° between the line of rope LC1 and the direction of the wind V. This gives a force F of lift directed forward and the port side of the boat.

The underside is oriented towards the rear of the powered mobile.

It can be provided that the or each device is equipped with profiled elements extending parallel to the axis A1 of the body of the device and positioned in a fixed manner near the body of the device. These elements are used to deflect flow to limit delamination. They can be installed to the leading edge and the trailing edge of the device.

According to a non-illustrated embodiment, the thruster is also equipped with a propellant articulation system relative to said base. The articulation system makes it possible to move the thruster between a position erected perpendicular to the base, that is to say substantially vertical, and a position substantially parallel to the base, that is to say substantially horizontal, along from the deck of the boat. The system thus makes it possible to tilt the thruster on the deck in the case where the wind is too strong compared to the windward grip of the thruster and with respect to the stability of the boat. It is also possible to switch the thruster in the case where it is desired to reduce windholding in case of non-use, or to facilitate operations on the deck of the ship, such as loading or unloading, when it proves necessary.

The invention is not limited to the embodiments illustrated in the drawings. Accordingly, it should be understood that when the features mentioned in the appended claims are followed by reference signs, these signs are included solely for the purpose of improving the intelligibility of the claims and are in no way limiting to the scope of the claims. claims.

In addition, features or steps that have been described with reference to one of the embodiments set forth above may also be used in combination with other features or steps of other embodiments set forth above.

Claims (13)

A device, called a lift-generating device, intended to be placed in a moving fluid, such as air, in order to produce a lift force,
the device comprising a hollow body (1) elongated along an axis (A1), said body having two opposite walls (11, 12), said respectively intrados and extrados, said extrados and intrados walls being shaped so that the body presents in section transverse a camber line whose arrow is at least equal to 20% of the length of the rope (LC1) joining the connecting edges between said intrados and extrados walls,
said upper wall (12) having an opening (121) adapted to communicate with a first chamber (21) located inside said body and an opening (122) communicating with a second chamber (22) located inside said body ,
the device comprising a system (3) for limiting boundary layer separation: Configured to suck air selectively through the first or second chamber (21, 22) by, respectively, the first or second opening (121, 122), and / or Configured to blow air selectively from the first or second chamber (21, 22) through the first or second opening (121, 122), tangentially to said extrados wall (12) towards an edge of connection (111 or 112) between the walls (11, 12) intrados and extrados, characterized in that the body is substantially symmetrical about a plane of symmetry (P1) which is perpendicular to the line of rope (LC1) joining the connecting edges (111, 112) between said intrados and extrados walls, and which intersects said rope substantially in the middle,
and in that the two openings are positioned substantially symmetrically with respect to said plane of symmetry. Device according to claim 1, characterized in that , the intrados (11) and extrados (12) walls being connected to each other, the connecting edges (111, 112) between said walls are rounded to form an edge of attack and a trailing edge in the direction of the fluid in motion. Device according to one of the preceding claims, characterized in that said system (3) for limiting boundary layer separation comprises: A first suction and / or blowing system (31) communicating with the first opening (121) and arranged to depressurize the first chamber (21) or to blow air from the first chamber (21) to through said first opening (121), tangentially to said extrados wall in the direction of the connecting zone (112) between the intrados and extrados walls which is situated on the opposite side to the first opening (121), A second suction and / or blowing system (32) communicating with the second opening (122) and arranged to depressurize the second chamber or to blow air from the second chamber (22) through said second chamber; opening (122), tangential to said extrados wall in the direction of the connecting zone (111) between the intrados and extrados walls which is situated on the opposite side to the second opening (122), the first and second systems (31, 32) for suction and / or blowing may be separate or common in whole or in part. Device according to one of the preceding claims, characterized in that said system (3) for limiting boundary layer separation comprises at least a portion located outside the body and connected to the openings (121, 122) by conduits. Device according to one of the preceding claims, characterized in that said body having a partition wall (13) which separates the interior of the body so as to delimit said first and second chambers (21, 22), said partition wall (13) extending substantially transversely, preferably orthogonally, to said rope line (LC1). Device according to one of the preceding claims, characterized in that said boundary layer detachment limiting system (3) is configured to suck air selectively through the first or second chamber (21, 22) by , respectively, the first or the second opening (121, 122), said boundary layer detachment limiting system (3) comprises a discharge outlet oriented in a direction tangential to the extrados wall, and preferably orthogonal to the axis (A1) of the hollow body, to the connecting edge located downstream of the direction (V) of the moving fluid in which the device is placed. Device according to one of the preceding claims, characterized in that said device comprises profiled elements extending parallel to the axis (A1) of the body of the device and positioned in a fixed manner near the wall of the body of the device. Device according to one of the preceding claims, characterized in that said system (3) for limiting boundary layer separation comprises at least one centrifugal fan, preferably a centrifugal fan for each opening. Device according to one of the preceding claims, characterized in that said upper and lower walls are respectively convex and concave. Installation comprising a device according to one of the preceding claims, characterized in that the installation comprises means for directing the device for moving the device from a first position to a second distinct position, by pivoting the device around the device. an axis parallel, preferably coincidental, with the axis (A1) of said body of the device. Propellant, preferably aeolian, comprising several devices according to one of claims 1 to 9, characterized in that said devices are superimposed. Boat comprising an installation according to claim 10, characterized in that said installation is mounted (e) on the deck or on a superstructure of said boat. Boat according to claim 12, characterized in that said boat comprises a system of articulation of the device relative to the base, said articulation system being configured to allow the device to be moved in an upright position, in which, at the fixed state of the base to the deck of the boat, it extends perpendicularly to the deck of the boat, and a tilted position, in which, in the state fixed from the base to the deck of the boat, the device extends substantially parallel to the deck Of the boat.

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