The present invention relates to the field of magnetohydrodynamics, especially its use for the recovery of at least part of the residual energy of a turbine working fluid,

turbine is meant a rotary device for utilizing the energy of a working fluid to rotate a rotary shaft. The energy of the working fluid ^ characterized by its speed and its enthalpy is thus partly converted into mechanical energy that can be extracted by the rotary shaft. However, working fluid ie normally keeps downstream of the turbine, a significant residual energy, in the following description the terms "upstream" and "downstream" are defined relative to the normal direction of flow of the working fluid.

In the French patent application FR 2085190 ,, it has been proposed to use a magnetohydrodynamic generator in addition to a turbine to recover the ' energy in the turbine working fluid. In such a magnétohydrodynarnique generator, the flow of ionized fluid, subjected to a magnetic field in a direction perpendicular to the flow of ionized fluid, generates an electrical current between two electrodes spaced relative to each other in a another direction perpendicular to the flow of ionized fluid and the magnetic field.

In practice., However, the integration of such magnétohydrodynarnique generator and a turbine is not without drawbacks, particularly as regards the arrangement of the electrodes and means for generating the magnetic field in a vein of flow of turbine working fluid.

Purpose and Summary of the Invention

The present disclosure aims to overcome these drawbacks by proposing a ,, MHD generator for easier integration in an assembly comprising a turbine to be operated by the same working fluid.

each of the electrodes of each pair being disposed on one side of the channel defined by the pair of arms and said walls, the electrodes of each pair being spaced relative to each other in a direction perpendicular to said magnetic field and the flow of the working fluid in the channel delimited by the pair of arms and said walls. The magnet may be an electromagnet ,, possibly with soiénoïde can be advantageously: conductivity improved through the integration of carbon nanotube in the soul of the driver or be superconducting, but could also be a magnet permanen In one case as in the other, it could include a laminated core. the electrodes of each pair being spaced relative to each other in a direction perpendicular to said magnetic field and to the flow of working fluid in the channel delimited by the pair of arms and said walls. The magnet may be an electromagnet ,, possibly with soiénoïde can be advantageously: conductivity improved through the integration of carbon nanotube in the soul of the driver or be superconducting, but could also be a magnet permanen In one case as in the other, it could include a laminated core. the electrodes of each pair being spaced relative to each other in a direction perpendicular to said magnetic field and to the flow of working fluid in the channel delimited by the pair of arms and said walls. The magnet may be an electromagnet ,, possibly with soiénoïde can be advantageously: conductivity improved through the integration of carbon nanotube in the soul of the driver or be superconducting, but could also be a magnet permanen In one case as in the other, it could include a laminated core.

Thanks to these arrangements, it facilitates the arrangement of the electrodes and the poles of the magnet along two substantially mutually perpendicular axes and relative to the flow of working fluid. Furthermore, it may be limited to generating electricity as from a part of the working fluid of a turbine, which may be desired, for example, if the turbine is intended to provide a mechanical power relatively

important, that I handed magnétohydrodynarnique generator is designed to provide a significantly reduced electrical power, è ancillary "

In particular, each electrode of each pair of ' electrodes may be disposed on one arm of said pair of arms. In this case, for generating a magnetic field perpendicular to the flow of working fluid to the direction in which the electrodes are separated Tune each other, the magnet may comprise a core housed within one of said arms . However, an arrangement Alternative is also conceivable wherein each electrode of each pair is disposed on one of the walls delimiting the flow passage, the magnet then being arranged to generate a magnetic field oriented in the direction in which the arms are separated from one another.

To accelerate the flow of fluid through ie channel delimited by the walls and the arms, so to increase the performance of magnétohydrodynarnique generator, the first and second walls may converge towards one another in a flow direction flue gas to at least a first segment of the flow passage located upstream of said pair of arms. In this case, and in order to avoid a significant thrust reaction, especially when the magnétohydrodynarnique generator is installed in an outlet nozzle of a turbine engine, and particularly a turhomoteur rotary wing aircraft, the first and second walls may diverge from each other in a direction of flow of the working fluid on at least one second segment of the vein of

To enable the effective ionization of the working fluid, particularly a gaseous working fluid, said ionization device may take the form of a plasma torch. Such a plasma torch can in particular comprise a pair of electrodes connected to a generation of a DC electric potential alternative device or between the electrodes of this pair which is equal to or greater than the working fluid of the ionization potential, however, of other types of ionizers are also conceivable, such as an ionization device by injection of microwave, discharge or by héiicon Inducflf coupling, Furthermore, to facilitate ionization of the working fluid, ie generator may comprise an injection deviceionization upstream of said ioniser, as well as ' optionally a filter for recovering the low ionization potential elements downstream of the channel defined by the walls and the arms.

Relatively short distances between electrodes and opposite magnetic poles in the channel delimited by the pair of arms and the walls can be positive for the yield and efficiency of the MHD generator. To increase the amount of working fluid for the magneto hydrodynamic generation, while limiting the dimensions, the generator may comprise a plurality of pairs of arms each connecting the first and second walls downstream of said ioniser and, for each pair of arm, a magnet and a pair of electrodes. By dividing the magnetohydrodynamic generation of electricity between a plurality of channels, it is possible to increase the electrical power while maintaining a restricted flow section for each channel pairs of

In order to adjust more easily the magnetohydrodynamic generator to a turbine, the flow passage may be annular, said first and second walls being concentric about a central axis of the flow passage, and: said arms being radial,

The present disclosure also relates to a omachine tur comprising at least one such magnetohydrodynamic generator ,, and at least one turbine arranged to be actuated by the same working fluid that the magnetohydrodynamic generator. The magnetohydrodynamic generator can thus be used for example to recover at least part of the residual energy of the working fluid can not be operated by the turbine. This turbine engine may include in particular a combustion chamber upstream of the turbine and

magnétohydfOdynamique generator, to produce high enthaipîe combustion gas forming the turbine ia working fluid and downstream magnetohydrodynamic generator e including: ies high temperatures facilitate their ionization. Furthermore, to increase the enthalpy of the combustion gases and their flow boost ,, this can turbomachine comprising at least a compressor upstream of the combustion chamber and a first turbine coupled to said compressor through a first rotary shaft for its actuating It may also include a second turbine. In the latter case, this second turbine ,, which may in particular be located downstream of the first turbine fool upstream of the MHD generator, may be coupled to an output shaft to form a turbine engine,

In order to better exploit the residual energy of the working fluid that can not be operated by the turbine, the magnetohydrodynamic generator may be disposed in an outlet nozzle downstream of the turbine,

The present invention also relates to a method of magnetohydrodynamic power generation wherein a working fluid is at least partially ionized by an ionization device in a flow duct delimited by a first and a second wall, and a portion of the fluid Ionized work through a channel defined in ia flow passage by said walls and a pair of arms each connecting the first and second walls downstream of said ioniser, and is subjected to a magnetic field generated in the channel by a magnet in the direction perpendicular to the flow of working fluid., so as to generate an electric current between the electrodes of at least one pair of electrodes, each electrode of each pair being disposed d 'one side of the channel defined by the pair of arms and said walls, the electrodes of each pair being spaced relative to each other in a direction perpendicular to said magnetic field and to the flow of combustion gases in this channel, this magnetohydrodynamic method of electrical generation can in particular be used to recover residual energy of a working fluid having previously been used to drive at least one turbine. In particular, on board a vehicle powered by a turbine engine, the magnetohydrodynamic process can be used to generate electrical energy for powering auxiliary equipment of the vehicle other than the turbine engine.

The invention will be well understood and its advantages apparaîtron better at reading the following detailed description of embodiments shown by way of non-limiting examples. The description refers to the attached drawings;

- Figure 1 is a schematic perspective view of a rotary wing aircraft with a turbine engine equipped with a magnetohydrodynamic generator according to one embodiment;

- Figure 2 is a schematic longitudinal sectional view of one of turhomoteurs of Figure i;

- Figure 3A is a schematic perspective view of a portion of the magnetohydrodynamic generator turbine engine of Figure 2;

~ Figure 38 shows a detail of Figure 3A;

■■■ · Figure 4 is a schematic perspective view of a magnetohydrodynamic generator following: a second embodiment;

- Figure 5 is a schematic perspective view of a magnetohydrodynamic generator according to a third embodiment;

- Figure 6 is a schematic longitudinal sectional view of a turbine engine according to a fourth embodiment; and:

- Figure 7 is a schematic view of a gas turbine engine according to a fifth embodiment.

Detailed Description of the Invention

1 shows a rotary wing aircraft, specifically a helicopter 100, with a gas turbine engine to 1.0 î; 'Neroent action of its main rotor 102 and tail rotor 103 through a transmission 104. The turbine 101 includes a magnétoliydrodynamique generator 10 according to an embodiment to provide an electric current to various electrical consumers on board the helicopter 1.

As illustrated in greater detail in Figure 2 ia ,. the turbine engine 101 includes a gas generator with, in the direction of flow of the ' air, a compressor 201, a combustion chamber with an igniter 202 and injectors connected to a fuel supply circuit (not shown), and a first turbine 203, coupled to the compressor 201 through a first rotary shaft 204, downstream of the second turbine 203, the turbine engine 101 includes a second turbine coupled to a 2.05 second rotary shaft 206, which in the helicopter 1 is coupiable transmission 104 for driving the rotors 102, 103, Finally, downstream of the second turbine 205, the turbine engine includes a nozzle outlet 207 of the combustion gases.

strong enough electric field to ionize the combustion gases flowing at temperatures and high speeds through the annular passage 11 to create a cold electrically conductive plasma. This strong electric field may be DC or AC, an alternating field to prevent a thermal imbalance of the cold plasma. To facilitate the ionization of flue gas, the turbine engine 101 may also comprise an injection of low ionization potential device components, such as potassium, upstream of dlonisation device, injecting device elements low ionization potential can in particular be integrated into the circuit prevent a thermal imbalance of the cold plasma. To facilitate the ionization of flue gas, the turbine engine 101 may also comprise an injection of low ionization potential device components, such as potassium, upstream of dlonisation device, injecting device elements low ionization potential can in particular be integrated into the circuit prevent a thermal imbalance of the cold plasma. To facilitate the ionization of flue gas, the turbine engine 101 may also comprise an injection of low ionization potential device components, such as potassium, upstream of dlonisation device, injecting device elements low ionization potential can in particular be integrated into the circuit' Fuel supply, so that low ionization potential elements are injected into the combustion chamber 202 with the fuel,

On a first segment IIa of annular section 11 of flow of combustion gases in this magnetohydrodynamic generator 10, the walls 12, 13 converge in the direction of flow of the combustion gases to accelerate their flow, while on a second segment 11b, these walls 12, 13 diverge again in the direction of flow of the combustion gases so as to reduce their speed before they exit the nozzle 207. Between the converging segment IIa and the segment 11b divergent pairs .1.5 radial arms connect your walls 12, 13 so as to form channels 16 in the vein 11, each channel 16 being defined by the walls 12, 13 and the arms 15 of a pair. To avoid that the elements with a low ionization potential injected upstream are then expelled outside,

In the embodiment illustrated in greater detail in Figures 3A, 38, the magnetohydrodynamic generator 10 comprises, for each channel 16, at least one electrode 17 mounted on an inner face of each of the arms 15 bounding the channel 16 so to be exposed to combustion gases irradiated through this channel 16, as well as an electromagnet 18 with poles 18a, 18b opposing in the radial direction, covered respectively by the inner wall 12 and outer wall 13 ia a side to side 16, channel and connected by a ring 18c housed in one of the arms 15, laminated and surrounded by a solenoid 18d, so as to generate a magnetic field B in the channel 16 which is oriented in the radial direction and thus substantially perpendicular to the flow of combustion gas ionized in the channel 16.To generate a particularly strong magnetic field, the solenoid 18d can notably be superconducting.

Thus, in this embodiment, the flow of combustion gas ionized è through each channel 16, subjected to the magnetic field 8 generated by the étectroaimant 18 can generate an electromotive force and therefore an electric current between the electrodes 17, situated each side of the channel 16 and thus Tune opposite to each other in a direction perpendicular to both the direction of flow to the direction of the magnetic field 8.

In an alternative embodiment, illustrated by Figure 4 ia f the arrangement of the walls 12,13, the arms 15 and thus the channels 16 is: identical. However, the electrodes 17 corresponding: to each channel 15 are not mounted on the arm 15, but on the internal faces of walls 12,13 so as to be exposed to the channel 16, opposite maize in the radial direction, while electromagnet 18 is arranged to generate a magnetic field B is oriented in the direction substantially perpendicular to the radial direction and to the direction of flow of ionised combustion gas. Other elements of the magnetohydrodynamic generator 10 are similar to those of the first embodiment and are given the same reference numerals in the drawing,

Although the flow passage: 11 is annular in these two embodiments ,, to facilitate the integration of the magnetohydrodynamic generator 10 in the turbine engine 101, other shapes are also conceivable, for example to integrate the magnetohydrodynamic generator 10 in a flat nozzle. Thus, in another alternative embodiment. Illustrated in Figure 5, the flow passage has a rectangular section 1.1, but the magnetohydrodynamic generator according to this third embodiment is similar to any other point E that of the first embodiment, and equivalent components are given the same marks on this figure.

Although in the first embodiment, the magnetohydrodynamic generator 10 is located downstream of deu turbines 203, 205, 1! is also possible to place it between the two turbines 203, 205, as in the fourth embodiment illustrated in Figure 6, or directly downstream of the combustion chamber 202; upstream of the two turbines 203, 205, as in the fifth embodiment illustrated in Figure 7, in both cases, the elements of the magnetohydrodynamic generator 10 remain similar to those of the first embodiment and are given the same reference numerals in the figures ,

The operation of the magnetohydrodynamic generator 10 following each of these embodiments is also similar. In each case of gas. Resulting combustion of the combustion chamber 202 are at least partially ionized by If device 'Ionization 14, accelerated in the convergent segment IIa of the flow passage 11 before entering the i.6 channels defined by each pair of arms 15, where they are subjected to magnetic fields generated by the 8 éiectroalmants 18 towards substantially perpendicular to that of the flow of combustion gas ionized in each channel 16, for generating an electric current between the electrodes 17, electric current can in particular be used to power various devices on board the helicopter 1. at the outlet channel 18, the ' flow of combustion gas decelerates diverging segment 11b,

Although the present invention has been described with reference to specific embodiments, it is obvious that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by your claims. For example, although in each of the illustrated embodiments each channel 10 is equipped with only a single pair of electrodes 17, it is also possible to place several pairs of electrodes in each channel, these electrode pairs can for example a succession in the direction of flow of the working fluid in addition, these magnétohydrodynamlques generators could be used in other types of turbomachines that the illustrated turbine engines. In addition, individual features of the different embodiments discussed can be combined into additional embodiments. Therefore, the description and drawings should be considered illustrative rather than restrictive sense.

CLAIMS

1 magnétohydrodynarnique generator (10) comprising at least:

a vein (11) of flow of a working fluid delimited by a first wall (1.2) and a second wall (13);

an ionization device (14) of the working fluid;

a pair of arms (15) connecting each of your first and: second walls (12,13) ​​downstream of said ioniser (14) so ​​as to define between said arms (15) and said walls (12,13) ​​a channel (16) in the flow passage (II), said channel (16) being arranged to be traversed by a portion of the working fluid after ionization;

a magnet for generating a magnetic field (B) oriented in the direction perpendicular to the flow of the working fluid in the channel (16) delimited by the pair of arms (15) and said walls (12,13); and

at least one pair of electrodes (17), each of the electrodes (17) of each pair being disposed on one side of the channel (16) delimited by the pair of arms (15) and said walls (12,13), said electrodes (17) of each pair being spaced relative to each other in a direction perpendicular to said magnetic field (B) and to the flow of working fluid in the channel (16) delimited by the pair of arms ( 15) and said walls (12,13),

2, magnetohydrodynamic generator (10) according to claim 1, wherein each electrode (17) of each pair of electrodes (17) is arranged on an arm (15) of said pair of arms (15).

3, magnetohydrodynamic generator (10) according to claim 2, wherein the magnet comprises a core (18c) housed within one of said arms (15).

4, magnetohydrodynamic generator (10) according to any preceding claim, wherein the first and second seem (12,13) ​​converge towards each other in a direction

the flow of working fluid to at least one first segment (IIa) of the flow passage (ii) upstream of said pair of arms (15).

5, magnetohydrodynamic generator (10) according to claim 4, wherein thy first and second walls (12,13) ​​diverging Tune each other in a direction of flow of the working fluid on at least one second segment of the vein flow downstream of said pair of arms.

β. magnetohydrodynamic generator (10) according to any preceding claim wherein said ioniser (14) takes the form of a plasma torch,

7, magnetohydrodynamic generator (10) according to any preceding claim, comprising an injection device of low ionization potential elements upstream of said ioniser (14),

8. magnetohydrodynamic generator (10) according to any preceding claim, comprising a plurality of pairs of arms (15) each connecting the first and second walls. (.12,13) ​​downstream of said ioniser (14) and, for each pair of arms (15) ,, a magnet and at least a pair of electrodes (17),

9. magnetohydrodynamic generator (10) according to any preceding claim, wherein said flow passage (11) is annular, said first and second walls (12,13) ​​being concentric about a central axis (X) of the flow passage (11), and iesdlts arm (15) being radial.

10 A turbomachine comprising at least a magnetohydrodynamic generator (10) according to any preceding claim, and at least one turbine (203.205) arranged to be actuated by the same working fluid that the magnetohydrodynamic generator (10).

11 A turbomachine according to claim .1.0, comprising a combustion chamber (202) upstream of the turbine (203.205) and the magnetohydrodynamic generator (10).

12. The turbomachine according to claim 11, comprising at least one compressor (201) upstream of the combustion chamber (202) and a first turbine (203) coupled to said compressor (201) through a first rotary shaft (204) for actuation

13 A turbomachine according to claim 12 ,, comprising a second turbine (205),

14 A turbomachine according to any preceding claim, wherein the magnetohydrodynamic generator (10) is arranged in an outlet nozzle (207) downstream of the turbine (203).

15. A method MHD power generation wherein;

a working fluid is at least partially ionized by an ionization device (14) in a flow passage (11) delimited by a first and a second wall (12,13);

an ionized portion of the working fluid through a channel (16) delimited in the flow passage (11) through said walls (12,13) ​​and a pair of arms (15) each connecting the first and second walls (12,13 ) downstream of said ioniser (14) and is subjected to a magnetic field (8) generated by a magnet in this channel (16) in a direction perpendicular to the flow of working fluid so as to generate a current power between the electrodes (1?) of at least one pair of electrodes (.17), each of the electrodes (17) of each pair being disposed on one side of the channel (16) delimited by the pair of arms (15 ) and said walls (12,13), said electrodes (17) of each pair being spaced relative to each other in a direction perpendicular to said magnetic field (B) and theflow of combustion gas in the channel (16).