Drive arrangement with at least one controlled ventilation device, aircraft with at least one such drive arrangement

Description

[0001] The present application relates to a propulsion assembly comprising at least one ventilation device configured to cool at least one zone of the propulsion assembly as well as to an aircraft comprising at least one such propulsion assembly.

[0002] According to an embodiment visible on the Figure 1 , an aircraft 10 comprises a fuselage 12, wings 14 positioned on either side of the fuselage as well as propulsion units 16 positioned under the wings and connected to the latter by masts 18. Each propulsion unit 16 comprises a motorization 20 as well as a nacelle 22 surrounding the motorization 20 and making it possible in particular to channel an air flow towards the motorization 20.

[0003] The motorization 20 has an axis of rotation A20. For the remainder of the description, a longitudinal direction is a direction parallel to the axis of rotation A20. A longitudinal plane is a plane containing the axis of rotation A20. A transverse plane is a plane perpendicular to the axis of rotation A20. The concepts front / upstream and rear / downstream refer to the direction of flow of the airflow in the motorization 20 in operation, which flows from front / upstream to rear / downstream.

[0004] According to an embodiment visible on the Figure 2 , the propulsion assembly is a dual-flow turbojet. The engine 20 comprises, from front to rear, a fan 20.1, an engine core 20.2, an external wall 20.3 surrounding the engine core 20.2 as well as a first nozzle 20.4 in the extension of the engine core 20.2. The external wall 20.3 is also called the internal fixed structure or IFS (for Inner fixed structure in English).

[0005] The nacelle 22 generally has a tubular structure comprising an air inlet 22.1 upstream of the engine 20, an intermediate part 22.2 intended to surround the fan 20.1, a rear part 22.3 which can integrate thrust reversal means, positioned around the external wall 20.3 and generally terminated by a second nozzle 22.4. The nacelle 22 also has an internal wall 22.5 spaced from the engine 20, in particular from its external wall 20.3.

[0006] In operation, a primary flow circulates in the engine core 20.2 and exits via the first nozzle 20.4. A secondary flow exiting the fan 20.1 circulates in an annular duct 24 delimited by the outer wall 20.3 of the engine 20 and the inner wall 22.5 of the nacelle 22. The primary and secondary flows are ejected via the first and second nozzles 20.4, 22.4. According to one configuration, the outer wall 20.3 of the engine 20 comprises a thermal barrier and separates a hot zone Zc, inside the engine 20, and a cold zone Zf outside the engine 20, in the annular duct 24.

[0007] As illustrated on the Figure 2, the propulsion assembly 16 comprises at least one ventilation device 26 configured to cool certain zones of the propulsion assembly 16, in particular the engine core 20.2 as well as the zone between the external wall 20.3 and the engine core 20.2 (this zone being called Core zone in English) where equipment and systems of the engine 20 are installed. This ventilation device 26 generates flows of cold air 28 in the engine 20 and the nacelle 22.

[0008] This ventilation device 26 comprises, among other things, at least one ventilation hole 26.1, passing through the external wall 20.3 of the engine 20, which has a fixed passage section. The ventilation device 26 is designed for the most important needs, in particular during the takeoff phase of the aircraft with a high temperature on the ground and a high thrust of the engine 20 causing significant heating thereof.

[0009] Therefore, for certain flight phases such as the cruise phase for example, the passage section of the passage hole 26.1 is oversized for the cooling requirements. This oversizing leads to capturing too much air in the secondary flow and to reducing the thrust of the propulsion assembly 16, which results in an increase in energy consumption at identical thrust and flight conditions.

[0010] Document US2018 / 016933 A1 discloses an aircraft propulsion assembly according to the prior art.

[0011] The present invention aims to remedy all or part of the drawbacks of the prior art.

[0012] To this end, the invention relates to an aircraft propulsion assembly comprising a motor, a nacelle positioned around the motor, an annular duct positioned between the motor and the nacelle and configured to channel a flow of cold air as well as at least one ventilation device configured to cool at least one zone to be cooled of the propulsion assembly, the ventilation device comprising at least one ventilation hole which opens into the zone to be cooled.

[0013] According to the invention, the ventilation device is regulated and comprises: at least one flap movable between a closed position in which the flap closes the ventilation hole and an open position in which the flap at least partially clears the ventilation hole, at least one thermoelectric generator configured to generate an electric current by recovering part of the heat produced by the motorization, at least one servo control configured to control the position of the flap using the electric current generated by the thermoelectric generator.

[0014] This solution provides a regulated ventilation system, whereby the cross-section of the ventilation hole fitted with the valve and the flow rate of air drawn can be adjusted according to cooling requirements. The use of a thermoelectric generator makes it possible to use a resource available in the propulsion system to move the valve and / or regulate its position.

[0015] According to another characteristic, the ventilation device comprises at least one electric actuator configured to move the valve in at least a first direction among a direction going from the open position to the closed position and a direction going from the closed position to the open position.

[0016] According to another characteristic, the ventilation device comprises at least one spring configured to push and maintain the valve in the open position, the electric actuator being configured to move the valve from the open position to the closed position against the forces exerted by the spring.

[0017] According to one embodiment, the ventilation device comprises at least one electrical cable connecting the thermoelectric generator and the electric actuator so that the electrical current generated by the thermoelectric generator powers the electric actuator.

[0018] According to another characteristic, the ventilation device comprises at least one converter comprising a function configured to transform the electric current generated by the thermoelectric generator into a supply current to power the electric actuator, a given value of the supply current being a function of a given value of the current generated by the thermoelectric generator and corresponding to a given position of the valve.

[0019] According to another embodiment, the ventilation device comprises at least one relay configured to receive a power current and transmit it to the electric actuator as a supply current depending on a control current generated by the thermoelectric generator.

[0020] According to another characteristic, the relay is configured to occupy an activated state, when the control current has a value lower than a threshold value, in which the relay authorizes the passage of the power current, the supply current having a value equal to that of the power current, as well as a deactivated state, when the control current has a value greater than or equal to the threshold value, in which the relay blocks the power current, the supply current having a zero value.

[0021] According to another characteristic, the ventilation device comprises at least one switch, positioned between a power supply and the relay, configured to occupy a passing state in which the switch transmits the power current to the relay and a blocked state in which the switch blocks the power current.

[0022] According to another feature, the thermoelectric generator is positioned downstream of the ventilation hole so that an air flow passing through the ventilation hole impacts the thermoelectric generator.

[0023] According to another characteristic, the thermoelectric generator comprises a first face in contact with a cold source or with a cold environment cooled by a cold source as well as a second face in contact with a hot source or a hot environment heated by a hot source which has a temperature gradient with the cold source or the cold environment, the thermoelectric generator being positioned so that its second face is in contact with a hot source to be cooled or with a hot environment to be cooled.

[0024] According to one configuration, the motorization comprises a motor core delimited by a casing, an external wall surrounding the motor core, distant from the casing and delimiting the annular duct, as well as an intermediate zone positioned between the casing of the motor core and the external wall, the external wall having an inner face oriented towards the motor core and an outer face opposite the inner face, the zone to be cooled corresponding to the intermediate zone and the ventilation hole passing through the external wall.

[0025] According to one arrangement, the thermoelectric generator is positioned at the outer wall and has a first face located at the outer face of the outer wall and in contact with the flow of cold air as well as a second face in contact with hot air present in the intermediate zone.

[0026] According to another arrangement, the thermoelectric generator is positioned at the level of the casing of the engine core and has a first face in contact with air present in the intermediate zone as well as a second face pressed against the casing of the engine core.

[0027] The invention also relates to an aircraft comprising at least one propulsion assembly according to one of the preceding characteristics.

[0028] Other characteristics and advantages will emerge from the description of the invention which follows, a description given by way of example only, with reference to the appended drawings, among which: There Figure 1 is a perspective view of an aircraft and in detail of a propulsion unit, The Figure 2 is a longitudinal section of a propulsion assembly illustrating an embodiment of the prior art, The Figure 3is a longitudinal section of a part of a propulsion assembly comprising a ventilation device illustrating an embodiment of the invention, The Figure 4 is a schematic representation of a ventilation device comprising a valve in the open position illustrating an embodiment of the invention, The Figure 5 is a schematic representation of the ventilation device visible on the Figure 4 , the valve being in the closed position, The Figure 6 is a longitudinal section of a part of a propulsion assembly comprising a ventilation device illustrating another embodiment of the invention, The Figure 7 is a schematic representation of a ventilation device comprising a valve in the open position illustrating another embodiment of the invention, The figure 8 is a schematic representation of the ventilation device visible on the Figure 7 , the valve being in the closed position.

[0029] According to an embodiment visible on the figures 3 And 6 , a propulsion assembly 30 of an aircraft comprises a motor 32, a nacelle 34 positioned around the motor 32 as well as an annular duct 36 configured to channel a flow of cold air, called secondary flow, between the motor 32 and the nacelle 34.

[0030] The engine 32 comprises, from front to rear, a fan (not shown), an engine core 38 (this zone being called Core zone in English) delimited by a casing 38.1, an external wall 40 surrounding the engine core 38, distant from its casing 38.1, as well as a first nozzle 42 extending the engine core 38. The external wall 40 is also called internal fixed structure or IFS (for Inner fixed structure in English). According to one configuration, the external wall 40 comprises at least one portion spaced from the engine core 38 which has an inner face Fint oriented towards the engine core 38 and an outer face Fext opposite the inner face Fint. According to one embodiment, the external wall 40 comprises a sandwich panel which has at least one honeycomb structure interposed between an outer skin forming the outer face Fext and an inner skin forming the inner face Fint.According to one design, the outer wall 40 includes thermal insulation at the inner face Fint.

[0031] The motorization 32 comprises an intermediate zone 44 positioned between the casing 38.1 of the motor core 38 and the external wall 40.

[0032] The nacelle 34 generally has a tubular structure comprising an air inlet upstream of the engine 32, an intermediate part intended to surround the fan, a rear part 46 which can integrate thrust reversal means, positioned around the external wall 40 and generally terminated by a second nozzle 48. The nacelle 34 also has an internal wall 50 spaced from the engine 32, in particular from its external wall 40.

[0033] In operation, a primary flow circulates in the engine core 38 and exits via the first nozzle 42. A secondary flow exiting the fan circulates in the annular duct 36 delimited by the external wall 40 of the engine 32 and the internal wall 50 of the nacelle 34. The primary and secondary flows are ejected via the first and second nozzles 42, 48. The external wall 40 of the engine 32 separates a hot zone Zc inside the engine 32, in the intermediate zone 44, and a cold zone Zf outside the engine 32, in the annular duct 36.

[0034] The propulsion assembly 30, the motorization 32 and the nacelle 34 are not further described because they may be identical to those of the prior art.

[0035] The propulsion assembly 30 comprises at least one ventilation device 52, configured to cool at least one zone to be cooled of the propulsion assembly 30 and comprising at least one ventilation hole 54 which has a passage section, passing through a first wall in contact with the flow of cold air and opening into the zone to be cooled, the first wall separating hot and cold zones Zc, Zf. According to one configuration, the zone to be cooled corresponds to the intermediate zone 44 and the first wall corresponds to the external wall 40.

[0036] According to embodiments visible on the figures 4, 5 , 7 and 8, the ventilation device 52 is said to be regulated because it allows the regulation of the ventilation. For this purpose, it comprises a valve 56 as well as an articulation 58, connecting the valve 56 and the first wall, configured to allow the valve 56 to occupy a closed position in which the valve 56 closes the ventilation hole 54 and an open position in which the valve 56 at least partially clears the ventilation hole 54.According to one configuration, the valve 56 is configured to occupy a first extreme position corresponding to the closed position in which the passage section of the ventilation hole 54 has a zero value as well as a second extreme position corresponding to a completely open position in which the passage section of the ventilation hole 54 has a maximum value and intermediate positions for each of which the passage section of the ventilation hole 54 has a value between the zero value and the maximum value. According to one embodiment, the articulation 58 comprises a pivoting connection. In the open position, the valve 56 is located in the hot zone Zc.

[0037] The ventilation device 52 comprises at least one electric actuator 60 configured to move the valve 56. The electric actuator 60 is powered by a supply current 60.1 having a given value. According to one arrangement, the electric actuator 60 comprises a first end connected to the first wall and a second end connected to the valve 56.

[0038] According to one configuration, the electric actuator 60 is configured to position the valve 56 in a given position between the closed position and the fully open position depending on the value of the supply current 60.1.

[0039] According to one embodiment, the ventilation device 52 comprises at least one spring 62 configured to move the valve 56 into the open position and maintain it in this position. In addition, the electric actuator 60 is configured to move the valve 56 from the open position to the closed position against the forces exerted by the spring 62. For the present application, the term spring 62 covers any return means.

[0040] More generally, the electric actuator 60 is configured to move the valve 56 in at least a first direction among a direction going from the open position to the closed position and a direction going from the closed position to the open position as well as at least one spring 62 configured to move the valve in a second direction opposite to the first direction. The solution in which the spring 62 pushes the valve 56 into the open position is preferred because the ventilation hole 54 is automatically in the fully open position in the event of a malfunction in particular of the electric actuator 60.

[0041] According to the first and second embodiments visible on the figures 3 to 8, the ventilation device 52 comprises at least one thermoelectric generator 64 called TEG (for Thermo Electrical Generator in English) comprising a first face 66.1 in contact with a cold source or with a cold environment cooled by a cold source as well as a second face 66.2 in contact with a hot source or a hot environment heated by a hot source which has a temperature gradient with the cold source or the cold environment, the thermoelectric generator 64 producing an electric current at a given value as a function of the temperature gradient between the cold and hot sources. The heat transfer between the cold source and the first face 66.1 can be obtained by conduction when the cold source is in direct contact with the first face 66.1 or by convection when the cold source is distant from the first face 66.1. The heat transfer between the hot source and the second face 66.2 can be obtained by conduction when the hot source is in direct contact with the second face 66.2 or by convection when the hot source is distant from the second face 66.2.

[0042] According to one configuration, the thermoelectric generator 64 comprises at least one plate comprising semiconductors and uses the Seebeck effect to produce electricity as a function of the temperature gradient between the first and second faces 66.1, 66.2.

[0043] According to the first embodiment visible on the figures 3 to 5, the electric current generated by the thermoelectric generator 64 is used to power the electric actuator 60. For this purpose, the ventilation device 52 comprises at least one electric cable 68 connecting the thermoelectric generator 64 and the electric actuator 60. According to one configuration, the ventilation device 52 comprises at least one converter 70, the electric cable 68 comprising a first section 68.1 connecting the thermoelectric generator 64 and the converter 70 as well as a second section 68.2 connecting the converter 70 and the electric actuator 60. For the present application, an electric cable is understood to mean a single electric cable or several electric cables grouped into a cable bundle.

[0044] The converter 70 comprises a function configured to transform the low-value electric current generated by the thermoelectric generator 64 into a supply current 60.1 for the electric actuator, a given value of the supply current 60.1 being a function of a given value of the electric current generated by the thermoelectric generator 64 and corresponding to a given position of the valve 56. This function makes it possible to match a fixed position of the electric actuator 60 (therefore an opening angle of the valve 56) with a value of the current produced by the thermoelectric generator 64. This solution makes it possible to obtain fine regulation of the ventilation.

[0045] According to this first embodiment, the ventilation device 52 is autonomous, the position of the valve 56 being adjusted according to the temperature gradient between the cold and hot sources Zf, Zc. The greater the temperature gradient, which corresponds to a significant cooling requirement, the closer the valve 56 occupies a position to the fully open position. Conversely, the less the temperature gradient, which corresponds to a low cooling requirement, the closer the valve 56 occupies a position to the closed position.

[0046] According to one configuration, the function of the converter 70 is configured so as to limit the fixed positions occupied by the electric actuator 60. Thus, a given fixed position of the electric actuator 60 corresponds to at least one range of temperature gradients and not to a temperature gradient.

[0047] According to a second embodiment visible on the figures 6 to 8 , the ventilation device 52 comprises at least one relay 74 configured to receive a high-value power current 74.1, coming from an electrical power supply of the aircraft, and transmit it to the electric actuator 60 as a supply current 60.1 as a function of a control current 74.2.

[0048] The control current 74.2 is generated by the thermoelectric generator 64.

[0049] According to this second embodiment, the aircraft comprises a power supply 76 generating the power current 74.1 intended for the ventilation device 52, more particularly for the relay 74. According to one arrangement, the ventilation device 52 comprises at least one switch, positioned between the power supply 76 and the relay 74, configured to occupy an on state in which the switch transmits the power current 74.1 to the relay 74 and a blocked state in which the switch blocks the power current 74.1. Thus, the ventilation device 52 can be deactivated simply. This switch is positioned in the aircraft so as to be operable by an operator. This solution is more particularly suitable for manual operations on the ground. Thus, the functionality of the ventilation device 52 can be inhibited or tested on the ground.

[0050] According to one configuration, the relay 74 is configured to occupy an activated state, when the control current 74.2 has a value lower than a threshold value, in which the relay 74 authorizes the passage of the power current 74.1, the supply current 60.1 of the electric actuator 60 having a value equal to that of the power current 74.1 (to place the valve 56 in the closed position in the event of cold conditions), as well as a deactivated state, when the control current 74.2 has a value greater than or equal to the threshold value, in which the relay 74 blocks the power current 74.1, the supply current 60.1 of the electric actuator 60 having a zero value (to place the valve 56 in the fully open position in the event of hot conditions or a malfunction). The value of the control current 74.2 being proportional to the temperature gradient between the hot and cold sources Zc, Zf, the threshold value of the control current 74.2 corresponds to a determined value of the temperature gradient between the hot and cold sources, Zc, Zf.

[0051] According to this configuration, as long as the temperature gradient is greater than or equal to the determined value (i.e. in hot conditions), which corresponds to a situation for which cooling is necessary, the control current 74.2 has a value less than or equal to the threshold value. Consequently, the relay 74 is in the deactivated state, the supply current 60.1 has a zero value and the spring 62 maintains the valve 56 in the fully open position.

[0052] As soon as the temperature gradient is less than or equal to the determined value (i.e. in cold conditions), which corresponds to a situation for which cooling is not necessary, the control current 74.2 has a value greater than the threshold value. Consequently, the relay is in the activated state, the supply current 60.1 has a value equal to that of the power current and the valve 56 occupies a given position depending on the value of the power current.

[0053] This configuration simplifies the control of the position of the valve 56.

[0054] According to one operating mode, the power current 74.1 is modulated upstream of the relay according to the desired position for the valve 56.

[0055] According to another mode of operation, the power current 74.1 has a fixed value and the relay 74 comprises a function configured to modify the value of the power current 74.1 into a value for the supply current 60.1 which is a function of the value of the control current 74.2 generated by the thermoelectric generator 64. Alternatively, the electric current produced by the thermoelectric generator 64 is converted by a converter which comprises a conversion function (as for the first embodiment) into a control current 74.2 driving the relay 74.

[0056] Of course, the invention is not limited to these embodiments for the control of the valve 56.

[0057] Regardless of the embodiment, the ventilation device 52 is regulated. For this purpose, it comprises at least one thermoelectric generator 64 as well as at least one servo control 78 configured to control the position of the valve 56 using the electric current generated by the thermoelectric generator 64.

[0058] In the presence of an electric actuator 60, the servo control 78 controls the supply current 60.1 supplied to the electric actuator 60 and therefore the position of the valve 56 from a power current coming from at least one thermoelectric generator 64 of the ventilation device 52 and / or from a source of the aircraft independent of the ventilation device 52. This servo control 78 is configured to modulate the value of the supply current 60.1 from at least one characteristic of a control current, which may be the value of the current supplied by at least one thermoelectric generator 64 of the ventilation device 52.

[0059] According to a first configuration visible on the figures 3 And 6, the thermoelectric generator 64 is positioned at the level of the external wall 40, its first face 66.1 being located at the level of the external face Fext of the external wall 40 and in contact with the cold secondary flow, its second face 66.2 being in contact with the hot air present in the intermediate zone 44. According to this positioning, the maximum temperature gradient is of the order of a hundred degrees in operation. According to this configuration, the electric cable 68 is integrated in the external wall 40. According to this first configuration, the thermoelectric generator 64 is positioned close to a transverse plane passing through the trailing edge of the second nozzle 48.

[0060] According to another configuration, the thermoelectric generator 64 is positioned at the level of the casing 38.1 of the engine core 38 which is very hot, its second face 66.2 being pressed against the casing 38.1, the first face 66.1 being in contact with the less hot air present in the intermediate zone 44. According to this positioning, the maximum temperature gradient can exceed 300°C. Thus, in this second configuration, the current supplied by the thermoelectric generator 64 can have a value significantly higher than that of the current supplied by a thermoelectric generator 64 positioned according to the first configuration. However, the integration of the electric cable 68 in the intermediate zone 44 proves to be more complex.

[0061] According to an arrangement visible on the figures 3 And 6, the thermoelectric generator 64 is positioned downstream of the ventilation hole 54 in a hot zone so that a flow of air passing through the ventilation hole 54 and heating up while circulating in the hot zone towards the rear of the motorization 32 impacts the thermoelectric generator 64, more particularly its second face 66.2.

[0062] According to one configuration, the thermoelectric generator 64 is positioned so that its second face 66.2 is in direct contact with a heat source to be cooled or with a hot environment to be cooled. This configuration makes it possible to obtain a ventilation device which self-regulates according to the cooling requirements.

[0063] Of course, the invention is not limited to the embodiments visible on the figures 3 to 8. Thus, the ventilation device 52 may comprise one or more ventilation holes 54 and one or more thermoelectric generators 64. In the presence of several ventilation holes 54, the valves 56 of these different ventilation holes 54 may all occupy the same position or different positions from one ventilation hole 54 to another. Thus, for at least one ventilation hole 54, the valve 56 may be in the closed position while the valves 56 of the other ventilation holes 54 occupy more or less open positions.

[0064] In addition, the same thermoelectric generator 64 can be used to regulate the passage section of several ventilation holes 54.

[0065] Regardless of the embodiment, the ventilation device is regulated, the passage section of the ventilation hole 54 equipped with the valve 56 not being constant but being able to vary according to the cooling requirements. Thus, the air flow taken from the secondary flow is adjusted according to the actual or estimated cooling requirements and can be automatically reduced during certain flight phases, such as the cruise phase for which the cooling requirements are lower than the maximum cooling requirement. Even if this solution leads to an increase in the on-board mass of the aircraft, the thrust gain is significantly greater, which makes it possible to obtain an overall reduction in the energy consumption of the aircraft.

[0066] Preferably, the ventilation device 52 comprises at least one spring 62 which pushes the valve 56. This solution is preferred because the ventilation hole 54 is automatically in the fully open position in the event of a malfunction of the electric actuator 60 or the power supply 76 coming from the aircraft or the thermoelectric generator 64.

Claims

1. Aircraft propulsion assembly comprising an engine (32), a nacelle (34) positioned around the engine (32), an annular duct (36) positioned between the engine (32) and the nacelle (34) and configured to channel a cold air stream and at least one ventilation device (52) configured to cool at least one zone to be cooled of the propulsion assembly, the ventilation device comprising at least one ventilation hole (54) which emerges in the zone to be cooled, the ventilation device being regulated and comprising at least one valve (56) that is movable between a closed position in which the valve (56) shuts the ventilation hole (54) and an open position in which the valve (56) at least partially frees the ventilation hole (54), and at least one thermoelectric generator (64) configured to generate an electric current; characterized in that the ventilation device also comprises at least one servocontrol mechanism (78) configured to control the position of the valve (56) by using the electrical current generated by the thermoelectric generator (64).

2. Propulsion assembly according to the preceding claim, characterized in that the ventilation device (52) comprises at least one electric actuator (60) configured to displace the valve (56) in at least one first direction out of a direction going from the open position to the closed position and a direction going from the closed position to the open position.

3. Propulsion assembly according to the preceding claim, characterized in that the ventilation device (52) comprises at least one spring (62) configured to push and keep the valve (56) in the open position, the electric actuator (60) being configured to displace the valve (56) from the open position to the closed position against the efforts exerted by the spring (62).

4. Propulsion assembly according to one of Claims 2 and 3, characterized in that the ventilation device (52) comprises at least one electric cable (68) linking the thermoelectric generator (64) and the electric actuator (60) such that the electrical current generated by the thermoelectric generator (64) powers the electric actuator (60).

5. Propulsion assembly according to the preceding claim, characterized in that the ventilation device (52) comprises at least one converter (70) comprising a function configured to transform the electric current generated by the thermoelectric generator (64) into a power supply current (60.1) to power the electric actuator (60), a given value of the power supply current (60.1) being a function of a given value of the current generated by the thermoelectric generator (64) and corresponding to a given position of the valve (56).

6. Propulsion assembly according to one of Claims 2 and 3, characterized in that the ventilation device (52) comprises at least one relay (74) configured to receive a power current (74.1) and transmit it to the electric actuator (60) as power supply current (60.1) as a function of a control current (74.2) generated by the thermoelectric generator (64).

7. Propulsion assembly according to the preceding claim, characterized in that the relay (74) is configured to occupy an activated state, when the control current (74.2) has a value lower than a threshold value, in which the relay (74) allows the passage of the power current (74.1), the power supply current (60.1) having a value equal to that of the power current (74.1), and a deactivated state, when the control current (74.2) has a value greater than or equal to the threshold value, in which the relay (74) blocks the power current (74.1), the power supply current (60.1) having a zero value.

8. Propulsion assembly according to one of Claims 6 and 7, characterized in that the ventilation device (52) comprises at least one switch, positioned between a power supply (76) and the relay (74), configured to occupy an on state in which the switch transmits the power current (74.1) to the relay (74) and an off state in which the switch blocks the power current (74.1).

9. Propulsion assembly according to one of the preceding claims, characterized in that the thermoelectric generator (64) is positioned downstream of the ventilation hole (54) such that an air stream passing through the ventilation hole (54) impacts the thermoelectric generator (64).

10. Propulsion assembly according to one of the preceding claims, characterized in that the thermoelectric generator (64) comprises a first face (66.1) in contact with a cold source or with a cold ambience cooled by a cold source and a second face (66.2) in contact with a hot source or a hot ambience heated by a hot source which exhibits a temperature gradient with the cold source or the cold ambience and in that the thermoelectric generator (64) is positioned such that its second face (66.2) is in contact with a hot source to be cooled or with a hot ambience to be cooled.

11. Propulsion assembly according to one of the preceding claims, characterized in that the engine (32) comprises an engine core (38) delimited by a shroud (38.1), an outer wall (40) surrounding the engine core (38), away from the shroud (38.1) and delimiting the annular duct (36), and an intermediate zone (44) positioned between the shroud (38.1) of the engine core (38) and the outer wall (40), the outer wall (40) having an inner face (Fint) oriented towards the engine core (38) and an outer face (Fext) opposite the inner face (Fint), the zone to be cooled corresponding to the intermediate zone (44) and the ventilation hole (54) passing through the outer wall (40).

12. Propulsion assembly according to the preceding claim, characterized in that the thermoelectric generator (64) is positioned at the outer wall (40) and has a first face (66.1) situated at the outer face (Fext) of the outer wall (40) and in contact with the cold air stream and a second face (66.2) in contact with a hot air present in the intermediate zone (44).

13. Propulsion assembly according to Claim 11, characterized in that the thermoelectric generator (64) is positioned at the shroud (38.1) of the engine core (38) and has a first face (66.1) in contact with air present in the intermediate zone (44) and a second face (66.2) pressed against the shroud (38.1).

14. Aircraft comprising at least one propulsion assembly according to one of the preceding claims.