PROPULSION UNIT OF AN AIRCRAFT WITH AN UNDUCTED PROPELLER

Abstract

The propulsion assembly comprises: - a pylon (102) designed to be fixed to a wing of the aircraft; - an unducted propeller (104); - a turbomachine (106) designed to drive the propeller (104) around an axis of rotation (X); - between the pylon (102) and the turbomachine (106): • an upstream suspension (110) designed to perform a force recovery in a direction called the upstream recovery direction (A1), • two thrust recovery suspensions (114) designed to perform a force recovery in two directions having a projection on a vertical plane (P) passing through the engine axis (X) in a direction called the thrust recovery direction (A3), in which the upstream recovery direction (A1) and the thrust recovery direction (A3) intersect at a point called the convergence point (PC).The convergence point (PC) is located in the vertical plane (P), in a zone (Z) extending under the axis of rotation (X) and between a vertical (V1) passing through a center (G) of aerodynamic thrust of the propeller (104) and a vertical (V2) passing through a point of attachment (PF) of the upstream suspension (110) to the turbomachine (106). Figure for the abstract: Fig. 1.

Description

Title of the invention: PROPULSION UNIT OF AN AIRCRAFT WITH AN UNDUCTED PROPELLER Technical field of the invention

[0001] The present invention relates to a propulsion unit for an aircraft with an unducted propeller. Technological background

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those currently in circulation, requiring the implementation of technological solutions to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0003] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of aircraft.

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

[0005] This sustained research and development work covers new generations of aircraft engines, the lightening of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as essential complements to technological progress, aeronautical biofuels.

[0006] A propulsion unit for an aircraft is known from the state of the art, comprising: - a pylon designed to be fixed to a wing of the aircraft; - a shrouded propeller, generally called a fan; - a turbomachine designed to drive the propeller around an axis of rotation; - between the pylon and the turbomachine: • an upstream suspension designed to achieve force recovery in a direction called the upstream recovery direction, • two thrust recovery suspensions designed to achieve force recovery in two directions having a projection onto a vertical plane passing through the engine axis in a direction called the thrust recovery direction, in which the upstream recovery direction and the thrust recovery direction intersect at a point called the convergence point.

[0007] In this case of a ducted propeller (fan), it is known that the point of convergence is located on the axis of rotation, or even in a zone of the vertical plane extending symmetrically above and below the axis of rotation, within a predefined ratio of a propeller height, and, from upstream to downstream, from one end of a propeller nose to a high-pressure compressor.

[0008] However, the case of unducted propellers is not described in the state of the art. However, the forces in the case of an unducted propeller are not distributed in the same way as in the case of a ducted propeller.

[0009] When the turbomachine produces thrust while the aircraft is subjected to maneuvering loads (i.e. aerodynamic forces on the propeller), the turbomachine undergoes significant stresses. In particular, the turbomachine comprises a casing, the part of which between the planes of the upstream and downstream suspensions undergoes significant bending (from the English "back-bone bending") which creates clearance closures, or even wear degrading the performance of the turbomachine.

[0010] For example, as is known per se, the turbomachine generally comprises a high-pressure body (“HP core” in English), a high-pressure compressor, a high-pressure turbine, a low-pressure turbine and an exhaust casing. In the case where the part undergoing the bending includes a casing of the high-pressure body, the latter undergoes forces causing it to bend and increasing the clearances of the high-pressure compressor and the high-pressure turbine, thus increasing its fuel consumption, and its exhaust gas temperature (from the English “Exhaust Gas Temperature” or EGT).

[0011] To this end, the invention is the result of technological research aimed at very significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of aircraft. For this purpose, the invention relates to a propulsion unit of an aircraft for an unducted propeller, which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0012] A propulsion unit for an aircraft is therefore proposed, comprising: - a pylon designed to be attached to a wing of the aircraft; - a turbomachine comprising an unducted propeller designed to be driven around an axis of rotation; - between the pylon and the turbomachine: • an upstream suspension designed to achieve force recovery in a direction called the upstream recovery direction, • two thrust recovery suspensions designed to achieve force recovery in two directions having a projection onto a vertical plane passing through the engine axis in a direction called the thrust recovery direction, in which the upstream recovery direction and the thrust recovery direction intersect at a point called the convergence point; characterized in that the point of convergence is located in the vertical plane, in a zone extending under the axis of rotation and between a vertical passing through an aerodynamic thrust center of the propeller and a vertical passing through a point of attachment of the upstream suspension to the turbomachine.

[0013] Indeed, the thrust of the turbomachine creates a first bending moment in the high-pressure body. This first moment changes sign depending on whether the point of convergence is located above or below the axis of rotation. In parallel, the aerodynamic forces of the propeller create a second moment in the high-pressure body. This second moment changes sign depending on whether the point of convergence is located upstream or downstream of the vertical passing through the center of gravity of the propeller.

[0014] Thus, by placing the point of convergence in the zone defined by the invention, the first and second moments are of opposite signs and compensate each other at least in part, which reduces the bending of the high pressure body.

[0015] It may be noted that, to obtain the same effect, the point of convergence could be placed in a zone extending above the engine axis and upstream of the vertical passing through the center of gravity of the propeller. However, this solution would have the disadvantage of requiring almost horizontal thrust recovery suspensions, which would make their implementation difficult.

[0016] The invention may further comprise one or more of the following optional features, in any technically possible combination.

[0017] Optionally, the propeller being designed to generate a thrust creating a first bending moment in a high pressure body of the turbomachine and the propeller being designed to be subjected to aerodynamic forces creating a second bending moment in the high pressure body of the turbomachine, the zone extends above a first straight line of the vertical plane, this first straight line being included in the area, parallel to the axis of rotation and passing through a point which is the intersection, on the one hand, of a second straight line of the vertical plane where the first and second moments exactly compensate each other and, on the other hand, of the vertical passing through the point of attachment of the upstream suspension to the turbomachine.

[0018] Also optionally, the zone extends downstream of the second straight line, the latter being included in the zone.

[0019] Also optionally, the zone extends downstream of a third straight line starting from the point of attachment of the upstream suspension to the turbomachine, downwards and upstream, and making an angle of 30° relative to the vertical passing through the point of attachment of the upstream suspension to the turbomachine, this third straight line being included in the zone.

[0020] Also optionally, the propulsion assembly further comprises a downstream suspension designed to carry out force recovery in a direction called the downstream recovery direction.

[0021] Also optionally, the downstream suspension is located downstream of the thrust recovery suspensions.

[0022] Also optionally, the downstream suspension is located upstream of the thrust recovery suspensions.

[0023] Also optionally, in which the upstream recovery direction is oblique to the axis of rotation, that is to say that the upstream recovery direction makes an angle of between 50° and 80° with the axis of rotation.

[0024] Also optionally, the upstream recovery direction is substantially perpendicular to the axis of rotation, for example to within 5°.

[0025] An aircraft comprising a propulsion unit according to the invention is also proposed. Brief description of the figures

[0026] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: - [Fig. 1] is a side sectional view of a first propulsion unit of an aircraft according to the invention, in which a zone Z for locating a suspension convergence point is illustrated, - [Fig.2] is a side sectional view of a second propulsion unit of an aircraft according to the invention, in which zone Z is illustrated, - [Fig. 3] is a side sectional view of a third propulsion unit of an aircraft according to the invention, in which zone Z is illustrated, - [Fig.4] is a view similar to that of [Fig.l], with zone Z according to a more restricted definition, and - [Fig.5] is a view similar to that of [Fig.l], with zone Z according to an even more restricted definition. Detailed description of the invention

[0027] With reference to [Fig.l], an example of a propulsion unit 100 of an aircraft according to the invention will now be described.

[0028] The propulsion assembly 100 firstly comprises a pylon 102 (also called a mast) designed to be fixed to a wing (not shown) of the aircraft.

[0029] The propulsion assembly 100 further comprises a turbomachine 106 comprising an unducted propeller 104 designed to be driven around an axis of rotation X and located under the pylon 102. The turbomachine 106 comprises in particular a high-pressure body (not shown).

[0030] The propulsion assembly 100 further comprises a fixed propeller, called stator 108, downstream of the propeller 104.

[0031] To suspend the turbomachine 106, the propulsion assembly 100 further comprises several suspensions.

[0032] In particular, the propulsion assembly 100 comprises an upstream suspension 110 between the pylon 102 and the turbomachine 106. The upstream suspension 110 is designed to carry out a force recovery in a direction called the upstream recovery direction AL.

[0033] The propulsion assembly 100 further comprises a downstream suspension 112 between the pylon 102 and the turbomachine 106. The downstream suspension 112 is designed to carry out a force recovery in a direction called the downstream recovery direction A2.

[0034] The propulsion assembly 100 further comprises two thrust recovery suspensions 114 between the pylon 102 and the turbomachine 106. The thrust recovery suspensions 112 are designed to provide force recovery in two directions respectively having a projection onto a vertical plane P (the plane of [Fig.l]) passing through the engine axis X in a direction called thrust recovery A3.

[0035] For example, as in [Fig.l], the downstream suspension 112 is located downstream of the thrust recovery suspensions 114.

[0036] As can be seen in [Fig.l], the upstream recovery direction A1 and the thrust recovery direction A3 intersect at a point called the convergence point PC, the latter being located in the vertical plane, in a zone Z of the latter. The zone Z extends under the engine axis X (the engine axis X being excluded) and between two verticals VI, V2 (the verticals being included). The first vertical VI passes through a center G of aerodynamic thrust of the propeller 104, this center G being normally located on the axis of rotation X and close to a center of gravity of the propeller 104. The second vertical V2 passes through a point PF of attachment of the upstream suspension 108 to the turbomachine 106.

[0037] The first moment (aerodynamic forces) is zero when the point of convergence PC is on the vertical VI and increases as the convergence point PC is moved downstream. On the other hand, the second moment (thrust forces) is zero when the convergence point PC is on the rotation axis X and increases as the convergence point PC is moved downward.

[0038] Thus, there is a straight line D which is oblique and where the first moment (aerodynamic forces) and the second moment (thrust forces) compensate each other exactly for the flight conditions of takeoff and maximum climb. In different flight conditions, the compensation could occur on a straight line slightly different from the straight line D. However, it is the forces during takeoff and maximum climb which are dimensioning so that it is the straight line D which is used. This straight line D intersects the vertical V2 at a point PD. Preferably, as illustrated in [Fig.l], the zone Z extends above (but not below) a horizontal line, parallel to the axis of rotation X, passing through the point PD. This horizontal line is included in the zone Z.

[0039] Preferably, the convergence point PC is located on the line D, because the first and second moments compensate each other exactly there, thus limiting as much as possible the bending of the high pressure body of the turbomachine 106.

[0040] The upstream recovery direction Al can be vertical, as in [Fig.l], so as to be perpendicular to the axis of rotation X, for example to within 5°. When the upstream recovery direction Al is vertical, the vertical V2 coincides with the upstream recovery direction AL

[0041] In the example of [Fig.l], the convergence point PC is located on the vertical V2.

[0042] [Fig.2] illustrates a case where the upstream recovery direction Al is oblique to the rotation axis X, that is to say that the upstream recovery direction Al makes, with the rotation axis X, an angle of between 50° and 80°.

[0043] In this case, as illustrated in [Fig.2], the convergence point PC is located in zone Z, at a distance from the verticals VI, V2.

[0044] [Fig. 3] illustrates a case where the downstream suspension 112 is located upstream of the thrust recovery suspensions 114.

[0045] [Fig.4] illustrates a more restricted definition of zone Z, according to which zone Z extends downstream (but not upstream) of line D, the latter being included in zone Z.

[0046] [Fig. 5] illustrates an even more restricted definition of zone Z, according to which zone Z extends downstream (but not upstream) of a straight line DF starting from the attachment point PF of the upstream suspension 108 to the turbomachine 106, downwards and upstream, and making an angle a of 30° relative to the vertical V2, this straight line DF being included in zone Z.

[0047] It is indeed difficult to tilt the suspension 110 to place the point of convergence upstream of the straight line DF, because the assembly of the suspension 110 would be too complicated due to the lack of space for the screwing tool of the suspension 110.

[0048] In conclusion, it will be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0049] In particular, the more restricted definitions of zone Z are not limited to the installations of the suspensions illustrated in Figures 4 and 5, but may also apply to the installations of the suspensions illustrated in Figures 2 and 3.

[0050] In the detailed presentation of the invention which is made above, the terms used must not be interpreted as limiting the invention to the embodiments set out in the present description, but must be interpreted to include all equivalents whose prediction is within the reach of those skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Claims

1. Propulsion assembly (100; 200; 300) of an aircraft, comprising: - a pylon (102) designed to be attached to a wing of the aircraft; - a turbomachine (106) comprising an unducted propeller (104) designed to be driven around an axis of rotation (X); - between the pylon (102) and the turbomachine (106): • an upstream suspension (110) designed to carry out force recovery in a direction called the upstream recovery direction (Al), • two thrust recovery suspensions (114) designed to carry out a force recovery in two directions having a projection on a vertical plane (P) passing through the engine axis (X) in a direction called the thrust recovery direction (A3), in which the upstream recovery direction (Al) and the thrust recovery direction (A3) intersect at a point called the convergence point (PC); characterized in that the point of convergence (PC) is located in the vertical plane (P), in a zone (Z) extending under the axis of rotation (X) and between a vertical (VI) passing through a center (G) of aerodynamic thrust of the propeller (104) and a vertical (V2) passing through a point of attachment (PF) of the upstream suspension (110) to the turbomachine (106).

2. Propulsion assembly (100; 200; 300) according to claim 1, wherein, the propeller (104) being designed to generate a thrust creating a first bending moment in a high-pressure body of the turbomachine (106) and the propeller (104) being designed to be subjected to aerodynamic forces creating a second bending moment in the high-pressure body of the turbomachine (106), the zone (Z) extends above a first straight line of the vertical plane (P), this first straight line being included in the zone (Z), parallel to the axis of rotation (X) and passing through a point (PD) which is the intersection, on the one hand, of a second straight line (D) of the vertical plane (P) where the first and second moments exactly compensate each other and, on the other hand, of the vertical (V2) passing through the attachment point (PF) of the upstream suspension (110) to the turbomachine (106).

3. Propulsion assembly (100; 200; 300) according to claim 2, in which the zone (Z) extends downstream of the second straight line (D), the latter being included in the zone (Z).

4. Propulsion assembly (100; 200; 300) according to claim 3, in which the zone (Z) extends downstream of a third straight line (DF) starting from the attachment point (PF) of the upstream suspension (108) to the turbomachine (106), downwards and upstream, and making an angle of 30° relative to the vertical (V2) passing through the attachment point (PF) of the upstream suspension (110) to the turbomachine (106), this third straight line (DF) being included in the zone (Z).

5. Propulsion assembly (100; 200; 300) according to any one of claims 1 to 4, further comprising a downstream suspension (112) designed to carry out a force recovery in a direction called the downstream recovery direction (A2).

6. Propulsion assembly (100; 200) according to claim 5, in which the downstream suspension (112) is located downstream of the thrust recovery suspensions (114).

7. Propulsion assembly (300) according to claim 5, in which the downstream suspension (112) is located upstream of the thrust recovery suspensions (114).

8. Propulsion assembly (200; 300) according to any one of claims 1 to 7, in which the upstream recovery direction (Al) is oblique relative to the axis of rotation (X), that is to say that the upstream recovery direction (Al) makes an angle of between 50° and 80° with the axis of rotation (X).

9. Propulsion assembly (100) according to any one of claims 1 to 8, in which the upstream recovery direction (Al) is substantially perpendicular to the axis of rotation (X), for example to within 5°.

10. Aircraft comprising a propulsion unit (100; 200; 300) according to any one of claims 1 to 9.

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