Propeller for an aircraft propulsion system, propulsion system, aircraft and associated methods

Abstract

A propeller (2) for a propulsion device (1) configured to be driven in rotation by at least one electric motor (3), the propeller (2) comprising a central hub (20) in which are mounted blades (21) extending radially with respect to said axis X, a propeller cone (22) extending along the axis X upstream of the central hub (20), each blade (21) having a foot (211) opposite the propeller cone (22) and a body (212) offset radially with respect to the propeller cone (22), at least one blade (21) having at least one cooling channel (5) comprising at least one inlet opening (51) formed in the body (212) and at least one outlet opening (52) formed in the foot (211) so as to guide a flow of cooling air (Fr) downstream of the propeller cone (22) to the electric motor (3). Figure from the summary: Figure 3

Description

Title of the invention: Propeller for an aircraft propulsion device, propulsion device, aircraft and associated method technical field

[0001] The present invention relates to the field of aircraft propulsion devices, in particular, a propulsion device comprising an electric motor for driving a propeller to provide electric propulsion for an aircraft.

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, in particular through the materials used and lighter on-board equipment, the development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aviation biofuels.

[0006] In order to reduce the use of fossil energy, it has been proposed to use a propulsion device comprising an electric motor to drive a propeller in rotation.

[0007] With reference to [Fig. 1], a propulsion device 100 for an aircraft comprising a propeller 102 driven in rotation about an axis of Rotation X by an electric motor 103 accelerates an external airflow F from upstream to downstream. The propeller 102 traditionally has a central hub 120 from which a plurality of blades 121 extend along a radial axis R. In practice, the central hub 120 of a propeller 102 generates significant drag and a resisting torque that produces no thrust. The same is true of the blade roots 121, which are mounted in the central hub 120. Therefore, as illustrated in [Fig. 1], a propeller 102 traditionally includes a propeller cone 122, also called a "spinner" or "spinner," mounted upstream of the central hub 120 to avoid such drag. The presence of such a propeller cone 122 advantageously allows for the accommodation of a variable pitch device 104 for the blades 121 of the propeller 102. Such a propeller cone 122 nevertheless deprives the propulsion device 100 of an external airflow F allowing for the direct cooling of the electric motor 103.Also, it is necessary to provide a cooling system (not shown) dedicated to the electric motor 103, which increases the cost and size of the propulsion device 100.

[0008] The invention thus aims to eliminate at least some of these drawbacks. PRESENTATION OF THE INVENTION

[0009] The invention relates to a propeller for an aircraft propulsion device extending longitudinally along an axis X oriented upstream to downstream, the propeller being configured to be driven in rotation by at least one electric motor along the axis X in order to accelerate an external airflow F upstream to downstream, the propeller comprising a central hub in which are mounted blades extending radially with respect to said axis X and a propeller cone extending along the axis X upstream of the central hub.

[0010] The invention is remarkable in that, each blade having a foot opposite the propeller cone and a body offset radially with respect to the propeller cone, at least one blade has at least one cooling channel comprising at least one inlet opening formed in the body and at least one outlet opening formed in the foot so as to guide a flow of cooling air downstream of the propeller cone to the electric motor.

[0011] Thanks to the invention, the root of a blade, which does not participate in propulsion, is advantageously used to optimally direct a flow of cooling air to the electric motor located downstream of the blade roots. Furthermore, the lower part of the blade body, generally "non-working" for propulsion, is advantageously used to capture an airflow. This effectively cools the electric motor. It is no longer necessary to use a bulky and heavy cooling system. The blade thus fulfills both a propulsion function and a cooling function, which is advantageous.

[0012] According to one aspect, the propeller cone has a closed outer surface so as to guide the airflow towards the blade body, in particular, towards the inlet opening. Thus, the propeller does not experience significant drag, which improves propulsion efficiency.

[0013] According to one aspect, the blade comprises at least one shuttering element mounted movable relative to the inlet opening so as to modify the quantity of cooling airflow in the cooling channel. This advantageously allows the quantity of cooling airflow to be adjusted according to requirements and / or flight conditions.

[0014] According to one aspect, the inlet opening is formed in a leading edge of the blade body. This allows for optimal capture while maintaining a small inlet opening size so as not to affect mechanical strength.

[0015] According to one aspect, the outlet opening extends in a longitudinal direction in the foot relative to the X axis. This allows the electric motor to be directly supplied with a cooling airflow.

[0016] According to another aspect, the outlet opening extends in a radial direction in the foot with respect to the X axis. This advantageously reduces the pressure loss during collection.

[0017] The invention also relates to a propulsion device for an aircraft extending longitudinally along an X-axis oriented from downstream to upstream, comprising a propeller, as previously presented, positioned upstream, and an electric motor, positioned downstream, configured to drive the propeller in rotation along the X-axis so as to cool the electric motor with the cooling airflow.

[0018] According to one aspect, the propulsion device includes rectifier vanes mounted upstream of the electric motor so as to straighten the cooling airflow. The straightened cooling airflow allows for optimal heat collection in a cooling device specific to the electric motor.

[0019] The invention also relates to an aircraft comprising at least one propulsion device as previously described.

[0020] According to one aspect, the aircraft comprises at least one wing, the propulsion device being mounted on the wing.

[0021] According to another aspect, the aircraft comprising at least one nacelle, the propulsion device is mounted in said nacelle, for example, in a nose of the aircraft.

[0022] The invention also relates to a method of using a propulsion device as described above, the method comprising steps consisting of: • Drive the propeller with the electric motor so that the blades provide propulsion by accelerating an external airflow, and • Capture a cooling airflow from the outside airflow via the inlet opening of the cooling channel formed in the body of the blade to the outlet opening of the cooling channel formed in the foot of the blade so as to guide the flow of cooling air downstream of the propeller cone to cool the electric motor.

[0023] According to one aspect, the method of use includes a step of controlling the movement of a movable-mounted obturator relative to the inlet opening so as to modify the quantity of the cooling airflow in the cooling channel. PRESENTATION OF THE FIGURES

[0024] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0025] Fig. 1 is a schematic representation in axial half-section of a propulsion device according to the prior art, here, by way of example, with a variable blade pitching device.

[0026] The [Fig.2] is a schematic representation of an aircraft according to one embodiment of the invention.

[0027] The [Fig.3] is a schematic representation in axial half-section of a propulsion device according to a first embodiment of the invention.

[0028] The [Fig.4] is a schematic representation in axial half-section of a propulsion device according to a second embodiment of the invention.

[0029] Fig. 5 is a schematic representation in axial half-section of a propulsion device according to a third embodiment of the invention with the obturating member in a first position.

[0030] Fig. 6 is a schematic representation in axial half-section of a propulsion device according to a third embodiment of the invention with the obturating member in a second position.

[0031] It should be noted that the figures set out the invention in detail to implement the invention, said figures being of course able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0032] With reference to [Fig. 2], the invention will be presented for an aircraft A comprising two wings W on which several propulsion devices 1 according to the invention are mounted. A propulsion device 1 is also mounted in a nacelle, for example, in the nose of the aircraft A. The propulsion devices 1 advantageously allow for electric propulsion. A propulsion device 1 according to a first One embodiment of the invention will be described in detail with reference to [Fig. 3].

[0033] The propulsion device 1 extends longitudinally along an upstream-to-downstream axis X. The propulsion device 1 comprises a propeller 2, positioned upstream, and an electric motor 3, positioned downstream, configured to drive the propeller 2 in rotation about the X axis so as to accelerate an external airflow F from upstream to downstream. According to the invention, the propeller 2 is also configured to draw a cooling airflow Fr from the external airflow F so as to cool the electric motor 3.

[0034] The invention is presented for a propeller 2 without an outer casing, but the invention also applies to a propeller 2 mounted in a peripheral outer casing.

[0035] The invention applies equally to a propeller 2 providing traction as to a propeller 2 providing propulsion, in particular, a propeller 2 placed upstream or downstream of the electric motor 3.

[0036] With reference to [Fig. 3], the propeller 2 comprises a central hub 20 in which blades 21 are mounted, extending along a radial axis R defined with respect to said axis X. Preferably, as illustrated in [Fig. 2], there are three blades 21, but their number could be different. The blades 21 are preferably arranged angularly. The propeller 2 further comprises a propeller cone 22 extending along the axis X upstream of the central hub 20. The propeller cone 22 is closed and prevents any airflow through it.

[0037] In this example, the central hub 20 is fixed to a rotating shaft of the electric motor 3. The central hub 20 could directly form the rotating shaft of the electric motor 3.

[0038] As illustrated in [Fig. 3], each blade 21 comprises a foot 211 opposite the propeller cone 22 and a body 212 offset radially with respect to the propeller cone 22. In practice, the propeller cone 22 has a maximum radius R22 with respect to the X-axis, and the foot 211 extends to a radial distance less than said maximum radius R22. Conversely, the body 212 extends to a radial distance greater than said maximum radius R22.

[0039] In order to reduce drag, the propeller cone 22 has an aerodynamic shape so as to guide the external airflow F from upstream to downstream, in a radial direction oriented outwards, i.e., towards the body 212 of the blades 21. Thus, the propeller cone 22 prevents the circulation of the external airflow F in an axial direction for a radius less than the maximum radius R22. In other words, the airflow F does not enter the cavity under the cone 22.

[0040] In this example, the propulsion device 1 further comprises a variable pitch device 4 for the blades 21 of the propeller 2, which is housed in the propeller cone 22, by Specifically, upstream of the central hub 20. With reference to [Fig. 3], each central hub 20 defines a housing in which a foot 211 of a blade 21 is configured to rotate about a radial axis R, i.e., to change the pitch angle of a blade 21. For this purpose, each housing may include bearings to allow rotational guidance. The variable pitch device 4 is connected to the feet 211 of the blades 21 to adjust the pitch angle. Such a variable pitch device 4 is known to those skilled in the art and will not be described in further detail. Such a variable pitch device 4 is optional. The invention also applies to blades 21 having a fixed pitch.

[0041] The invention is remarkable in that at least one blade 21 has at least one cooling channel 5 comprising at least one inlet opening 51 formed in the body 212 of the blade 21 and at least one outlet opening 52 formed in the root 211 of the blade 21 so as to guide a cooling airflow Fr downstream of the propeller cone 22 to the electric motor 3. Preferably, in order to allow optimal cooling, each blade 21 has a cooling channel 5. The blade 21 has a span and a chord.

[0042] In practice, under the combined effect of the speed of the outside airflow F and the rotation of the propeller 2, a dynamic pressure is generated in the inlet opening 51, which generates a flow of outside air Fr which is directed towards the electric motor 3.

[0043] With reference to [Fig. 3], the cooling channel 5 extends within the blade 21, specifically from the blade body 212 to the blade root 211, so as to cool the electric motor 3 by bypassing the propeller cone 22. In this example, the body 212 defines a first internal cavity 5a which forms an upper part of the cooling channel 5. The root 211 defines a second internal cavity 5b which forms a lower part of the cooling channel 5. The first internal cavity 5a has a height, defined along the radial axis R, which is between 5% and 20% of the span of the blade 21. The first internal cavity 5a has a length, defined along the radial axis X, which is between 50% and 75% of the chord of the airfoil of the blade root 211.

[0044] In this example, the inlet opening 51 extends to a radial distance greater than the maximum radius of the cone R22. The inlet opening 51 preferably extends in a radial direction so as to reduce the mechanical stresses applied to the blade 21. Preferably, the inlet opening 51 is of the Pitot type. Preferably, the inlet opening 51 is formed at the root of the blade 21, that is, as close as possible to the guide cone 22 in order to achieve optimal air capture. Preferably, the blade 21 has a leading edge and an opposing trailing edge; the inlet opening 51 is formed at the leading edge to improve the recording for all phases of flight.

[0045] Preferably, the inlet opening 51 has a height, defined along the radial axis R, which is between 5% and 15% of the blade span. Preferably, the first internal cavity 5a and the inlet opening 51 have similar heights.

[0046] The base of the body 212 of the blade 21 may have a bulge so as to ensure a compromise between mechanical resistance, propulsion efficiency and cooling performance.

[0047] According to the first embodiment shown in [Fig. 3], the outlet opening 52 extends longitudinally with respect to the X-axis in the foot 211. In particular, the outlet opening 52 extends longitudinally with respect to the X-axis through the central hub housing 20 in which the foot 211 of the blade 21 is mounted. This allows for direct cooling of the electric motor 3, which extends downstream of the central hub 20. The cooling channel 5 thus has a reduced length, which limits pressure losses and improves cooling. The foot 211 of the blade 21 has a bottom wall 23 that closes the foot 211.

[0048] According to a second embodiment shown in [Fig.4], the foot 211 of the blade 21 is open (outlet opening 52) and the cooling airflow Fr fills the cavity downstream of the cone 22. The central hub 20 includes a guide channel formed directly in the central hub 20.

[0049] Preferably, the electric motor 3 includes components requiring cooling, for example, electrical components, power components, magnetic windings, and others. Preferably, the electric motor 3 has a plurality of fins projecting from its outer surface, configured to be cooled by the circulation of the cooling airflow Fr. In this example, the electric motor 3 is mounted in a housing 7, also called a nacelle, which preferably extends downstream of the propeller cone 22. The housing 7 has a radius in this example that is substantially equal to the maximum radius of the cone R22. The cooling channel 5 is configured to inject the cooling airflow Fr into the housing 7. To allow optimal cooling in both configurations, it is preferable to ensure a seal between the propeller cone 22 and the housing 7.

[0050] According to one aspect, with reference to Figures 3 and 4, the propulsion device 1 comprises rectifier blades 6 mounted at the outlet of the cooling channel 5 so as to straighten the cooling airflow Fr in order to allow optimal cooling of the electric motor 3. Preferably, the rectifier blades 6 are mounted internally within the housing 7. Preferably, the rectifier blades 6 extend radially. As illustrated in Figures 3 and 4, the rectifier blades 6 are located upstream of electric motor 3.

[0051] The set of rectifier blades 6 forms an axial or conical rectifier. The rectifier blades 6 can be fixed or have adjustable / variable pitch. Such rectifier blades 6 reduce pressure losses by aligning the airflow with the electric motor 3 for a wide operating range. The rectifier blades 6 can be made of various materials meeting thermomechanical resistance requirements and can be produced by different methods, in particular, by additive manufacturing.

[0052] According to a third embodiment shown in Figures 5 and 6, the blade 21 includes at least one shuttering element 8 mounted movable relative to the inlet opening 51 so as to modify the quantity of cooling air Fr circulating in the cooling channel 5. The shuttering element 8 makes it possible to modify the area of ​​capture of the cooling air flow Fr by the inlet opening 51. The flow rate of the cooling air flow Fr can thus be modulated according to the desired cooling, the performance sought or the flight conditions.

[0053] In this example, the shuttering element 8 is in the form of a movable flap, but it is understood that other technologies could be suitable, for example, a flap. The shuttering element 8 extends in the radial direction and is capable of moving in the axial direction. In one aspect, the shuttering element 8 has a height and length that are similar to those of the inlet opening 51.

[0054] According to one variant, the shutter member 8 is controllable so as to move between an open position and a closed position of the inlet opening 51. Preferably, the blade 21 includes at least one displacement device (not shown) of the shutter member 8 configured to determine the position of the shutter member 8 according to parameters from the propulsion device 1, for example, cooling requirements, the speed of the electric motor 3, the flight phase of the aircraft, etc. Preferably, the displacement device includes an actuator such as a cylinder or similar device connected to the shutter 8 and receives a command from a computer in the propulsion system 1 or aircraft A. With reference to [Fig. 5], the shutter 8 is in a first position Pa in which it closes less than 50% of the inlet opening 51 so as to provide a significant flow rate of cooling air Fr. With reference to [Fig.6], the obturating organ 8 is in a second position Pb in which it obturates more than 50% of the inlet opening 51 so as to provide a low flow rate of cooling air Fr. .

[0055] According to another embodiment, the sealing element 8 is passively movable, in particular, depending on the pressure exerted by the cooling airflow Fr in the cooling channel 5 or depending on the positioning of the blade 21 (indexing relative to the hub 20). By way of example, a system is provided for An autonomous control system comprising an actuator to move the shutter 8 according to the temperature of the electric motor 3. For example, the electric motor 3 includes a temperature sensor which, when the temperature rises, acts on the actuator, specifically on a control cylinder. Movement by pivoting about the radial axis R can also be considered.

[0056] It should be noted that such a sealing member 8 is independent of the outlet opening 52. The sealing member 8 is thus compatible with the longitudinal outlet opening (first embodiment of [Fig.3]) or radial (second embodiment of [Fig.4]).

[0057] Alternatively, a sealing member may also be in an outlet opening 52.

[0058] Method of use

[0059] The invention also relates to a method of using a propulsion device 1, as described above. In this example, the propeller 2 has three blades 21 having a diameter of approximately 150 cm. Each blade 21 has an inlet opening 51 having a length, defined along the radial axis X, of approximately 30 mm and a height, defined along the radial axis R, of approximately 150 mm.

[0060] The method includes a step of driving the propeller 2 by the electric motor 3 so that the blades 21 provide a propulsion force by accelerating an external airflow F.

[0061] The method includes a step of capturing a cooling airflow Fr in the outside airflow F via the inlet opening 51 of the cooling channel 5 formed in the body 212 of the blade 21 to the outlet opening 52 of the cooling channel 5 formed in the foot 211 of the blade 21 so as to guide the cooling airflow Fr downstream of the propeller cone 22 to cool the electric motor 3.

[0062] By simulation, a cooling airflow volume Fr of between 300g / s and 900g / s is captured by the inlet openings 51. Such a volume is important and allows optimal cooling of the electric motor 3 for any phase of flight.

[0063] Advantageously, as soon as the electric motor 3 is rotating, a cooling airflow Fr is captured by the blade 21 to cool the electric motor 3. This prevents any risk of overheating of the electric motor 3. The overall size of the propeller 2 remains limited, which is advantageous. Furthermore, it is possible to modify or eliminate the cooling system dedicated to the electric motor 3 found in the prior art.

[0064] According to one aspect, the method includes a step of controlling the movement of a movable shuttering element 8 relative to the inlet opening 51 so as to modify the quantity of the cooling airflow Fr in the channel 5 cooling units depending on requirements.

Claims

Demands

1. Propeller (2) for an aircraft propulsion device (1) (A) extending longitudinally along an upstream-to-downstream axis X, the propeller (2) being configured to be driven in rotation by at least one electric motor (3) along the X axis in order to accelerate an upstream-to-downstream external airflow (F), the propeller (2) comprising: • a central hub (20) in which blades (21) are mounted, extending radially with respect to said X axis, • a propeller cone (22) extending along the X axis upstream of the central hub (20), • propeller (2) characterized in that each blade (21) has a root (211) opposite the propeller cone (22) and a body (212) offset radially with respect to the propeller cone (22),at least one blade (21) has at least one cooling channel (5) comprising at least one inlet opening (51) formed in a leading edge of the body (212) of the blade (21) and at least one outlet opening (52) formed in the root (211) so as to guide a flow of cooling air (Fr) downstream of the propeller cone (22) to the electric motor (3).

2. Propeller (2) according to claim 1, wherein the propeller cone (22) has an outer surface closed so as to guide the airflow towards the body (212) of the blades (21).

3. Propeller (2) according to any one of claims 1 to 2, wherein the blade (21) has at least one obturating member (8) mounted movable relative to the inlet opening (51) so as to modify the quantity of the cooling airflow (Fr) in the cooling channel (5).

4. Propeller (2) according to any one of claims 1 to 3, wherein the outlet opening (52) extends along a longitudinal direction in the foot (211) with respect to the X axis.

5. Propulsion device (1) for an aircraft (A) extending longitudinally along an X-axis oriented from downstream to upstream, comprising: • a propeller (2), according to any one of claims 1 to 4, positioned upstream, and • an electric motor (3), positioned downstream, configured to drive the propeller (2) in rotation around the X axis so as to cool the electric motor (3) with the cooling airflow (Fr).

6. Propulsion device according to claim 5, comprising straightener vanes (6) mounted upstream of the electric motor (3) so as to straighten the cooling airflow (Fr).

7. Aircraft (A) comprising at least one propulsion device (1) according to any one of claims 5 to 6.

8. A method of using a propulsion device (1) according to any one of claims 5 to 6, a method comprising steps of: • driving the propeller (2) by the electric motor (3) so that the blades (12) provide a propulsion force by accelerating an external airflow (F), and • capturing a cooling airflow (Fr) from the external airflow (F) via the inlet opening (51) of the cooling channel (5) formed in the body (212) of the blade (21) to the outlet opening (52) of the cooling channel (5) formed in the root (211) of the blade (21) so as to guide the cooling airflow (Fr) downstream of the propeller cone (22) to cool the electric motor (3).

9. A method of use according to claim 8 comprising a step of: • controlling the movement of a shuttering member (8) mounted movable relative to the inlet opening (51) so as to modify the quantity of the cooling airflow (Fr) in the cooling channel (5).