Aircraft turbine engine

Abstract

The invention relates to an aircraft turbine engine (1) which comprises a compressor (4, 6). The compressor is preferably a low-pressure compressor, and comprises at least one stator (18a, 18b). The stator comprises an inner casing (15) and an outer casing (16), and a plurality of circumferentially successive assemblies (21). Each assembly is intended to be set at an incidence angle within the compressor stator of an aircraft turbine engine, and comprises a first platform (50) engaging with the inner casing and a second platform (52) engaging with the outer casing (16). Each assembly comprises two stator blades (20) each having a blade root secured to the first platform and a blade tip secured to the second platform. Each assembly comprises a first rotational guide journal (34) secured to the first platform and a second rotational guide journal (36) secured to the second platform. The stator also comprises a control system (22) for setting the incidence angle of these assemblies. The outer casing is made of a composite material.

Description

[0001] 51787 AP

[0002] ASSEMBLY DESIGNED TO BE MOUNTED AT AN INCIDENCE POINT WITHIN AN AIRCRAFT TURBOMACHINE COMPRESSOR RECTIFIER, COMPRISING A PAIR OF VOLTS

[0003] 5 DESCRIPTION

[0004] TECHNICAL FIELD

[0005] The present invention relates to the field of compressor rectifiers for aircraft turbomachinery. It is applicable to all types of turbomachinery, in particular turbojets and turboprops.

[0006] STATE OF PRIOR ART

[0007] Turbomachine compressor rectifiers correspond to stator wheels, including variable pitch vanes also known as VSV vanes (from the English "Variable Stagger Vanes" or "Variable Stator Vanes").

[0008] A control system is provided to regulate the angle of attack of these blades, 15 that is, to simultaneously control the angle of attack of each blade of the same stator, according to the aerodynamic requirements within the compressor. Such a blade angle control system is described, for example, in document EP 1489267 A1, or in document EP 3 290657 A1.

[0009] Within a rectifier, each stator blade is mounted individually on an internal housing and on an external housing of this rectifier, so that it can pivot around an axis of rotation, also called the blade incidence alignment axis.

[0010] To do this, the rectifier housings, also called the inner and outer shells, must have openings for housing the trunnions to guide the rotation of the blades, these openings being able to be made through bosses provided on the housings, in particular on the outer housing of the rectifier.

[0011] In light of the above, the individual mounting of each stator vane on the rectifier housings complicates the rectifier's manufacture. Manufacturing is further complicated by the incidence control system, which requires as many levers as 51787 AP

[0012] The number of stator blades within the rectifier is limited. Furthermore, the maximum number of blades that can be integrated is restricted by the spacing between the trunnion holes and by the spacing between the plates or platforms. Wear on the guide bushings around the rotating trunnions can also be a drawback, caused by the small friction surface and the high bearing pressure.

[0013] Also noted is the presence of a torque to be taken up, resulting from the static and dynamic aerodynamic forces acting on the blade, and from the lever arm between the pivot axis and the center of application of the aerodynamic forces.

[0014] Besides the complex manufacturing process, this conventional design of compressor rectifiers also results in relatively significant maintenance.

[0015] DESCRIPTION OF THE INVENTION

[0016] To address at least partially the problems mentioned above relating to prior art achievements, the invention relates to an aircraft turbomachine comprising the features of claim 1.

[0017] 15 The invention consists of a technological breakthrough, by providing not to control the blades of the rectifier individually in incidence, but to control them by doublet of blades.

[0018] The manufacture and assembly of the rectifier are advantageously simplified, particularly by reducing the number of ports through the rectifier housings, the number of control levers, etc. This also results in a reduction of the rectifier's overall mass. The invention is therefore the result of technological research aimed at significantly improving aircraft performance and, in this respect, contributes to reducing the environmental impact of these aircraft (decarbonization).

[0019] 25 The proposed design also simplifies maintenance operations, mainly due to the reduction in the number of parts forming the compressor rectifier.

[0020] Since each assembly according to the invention comprises a doublet of blades, the mounting holes through the rectifier housings can be spaced further apart.

[0021] Others, where it is possible to increase the number of blades without placing the mounting holes too close together. In addition to simplifying manufacturing, this feature gives the external casing of the straightener a better capacity to deform in axial tension and compression, without the need for local thickenings dedicated to the mechanical strength of the part.

[0022] Finally, the design specific to the invention is particularly well-suited for manufacturing certain composite parts, such as the inner and outer casings, or the synchronized control ring belonging to the pitch control system for blade doublet assemblies. In particular, in the invention, the construction of the outer casing in composite material is advantageously made possible by the geometry of this casing, thanks to the wider circumferential spacing of the mounting holes for the assemblies. This greater spacing between the holes results from the blades being grouped in pairs. It is therefore no longer necessary to provide mechanical reinforcement elements at these holes.

[0023] This design according to the invention is also particularly suitable for the integration of an electrically actuator-driven control system.

[0024] Besides the possibility of using a greater number of blades, thus providing increased strength, the invention also offers the advantage of limiting wear due to the increased bearing surfaces. This significantly reduces maintenance. Furthermore, a self-compensating principle for aerodynamic torque can be observed, thanks to the symmetry of the two blades on either side of the angle of attack axis.

[0025] The invention also preferably has the following optional features, taken individually or in combination.

[0026] Preferably, the first and second platforms each have a general disc shape.

[0027] Preferably, the assembly defines an angle of incidence for the assembly, with the two stator blades preferably arranged on either side of this angle of incidence. 30.51787 AP

[0028] Preferably, the axis of incidence of the assembly is located closer to a leading edge of the two stator blades than to a trailing edge of these two blades. By moving this axis of rotation upstream relative to the blades, the difference in the angle of incidence between the two blades of the doublet is advantageously reduced as the incidence angle increases.

[0029] 5 Moving this axis of rotation as far upstream as possible towards the leading edge of the blades allows us to prioritize the accuracy of the angle at this point.

[0030] Preferably, the second rotational guide trunnion comprises a rotational guide portion, and, at its end, a rotational drive portion.

[0031] Preferably, the assembly is made from a single piece, although other designs, based on attaching several elements together, are also possible. In the preferred one-piece design, where the assembly is also said to be made from a single piece of material, or monobloc, or made in one piece, this assembly can, for example, be machined, cast, or additively manufactured from metal. A composite material is also possible, preferably with an organic matrix. For example, this could be a composite material of the type comprising glass and / or carbon fibers and a thermosetting or thermoplastic matrix. This same type of composite material is preferentially chosen for making the outer casing.

[0032] Preferably, the angle-of-attack control system includes a synchronized control ring made of composite material. One of the advantages of this type of construction, besides the weight reduction, lies in the low coefficient of thermal expansion of composite materials, which is about ten times lower than that of metallic materials. Here again, the same type of composite material as previously mentioned is preferably used.

[0033] 25 Other advantages and features of the invention will appear in the detailed, non-limiting description below.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] This description will be made with reference to the attached drawings, including: 51787 AP

[0036] - Figure 1 represents a schematic axial cross-sectional view of an aircraft turbomachine according to the invention;

[0037] - Figure 2 represents a half-axial cross-sectional view of part of a compressor of the turbomachine shown in the previous figure;

[0038] 5 - Figure 3 represents a perspective view of the part of the compressor shown in the previous figure;

[0039] - Figure 4 represents an enlarged and partial view of a rectifier of the compressor shown in Figures 2 and 3.

[0040] DETAILED EXPLANATION OF PREFERRED METHODS OF IMPLEMENTATION

[0041] With reference first to Figure 1, an aircraft turbomachine 1 is shown, according to a preferred embodiment of the invention. This is a twin-spool, turbofan engine. However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention.

[0042] The turbojet 1 has a central longitudinal axis 2 around which its 15 different components extend. It comprises, from upstream to downstream along a main direction 5 of gas flow through this turbojet, a fan 3, a low-pressure compressor 4, a high-pressure compressor 6, a combustion chamber 11, a high-pressure turbine 7 and a low-pressure turbine 8.

[0043] Conventionally, after passing through the blower, the air splits into a central primary flow 12a and a secondary flow 12b that surrounds the primary flow. The primary flow 12a flows into a main gas circulation channel 14a, passing through the compressors 4, 6, the combustion chamber 11, and the turbines 7, 8. The secondary flow 12b flows into a secondary channel 14b, radially delimited outwards by an engine casing, surrounded by a nacelle 9.

[0044] 25 Compressors 4, 6 and turbines 7, 8 are produced by alternating moving wheels, called rotor wheels, and stationary wheels, called stator wheels. In compressors 4, 6, the stator wheels are conventionally called compressor rectifiers. 51787 AP

[0045] The invention relates to the design of these rectifiers, within any of the compressors 4, 6. Subsequently, a preferred embodiment will be described in which the invention is integrated into the low pressure compressor 4, but the invention is therefore also applicable to the high pressure compressor 6.

[0046] 5. With reference to Figure 2, as mentioned above, the compressor 4 comprises alternating rotating wheels 17 and rectifiers 18a, 18b, in the axial direction of the turbojet. Thus, Figure 2 shows, from left to right, a first rectifier 18a, a rotating wheel 17, and a second rectifier 18b. Hereafter, only the first rectifier 18a will be described, but it is understood that the second rectifier 18b may have an identical or similar design.

[0047] The rectifier 18a can be likened to an annular ring of stator blades 20 mounted on an external housing 16 of this rectifier, preferably in the form of a ferrule centered on the axis 2. These stator blades 20 are intended to be simultaneously set in incidence, according to precise aerodynamic parameters, using a blade control system 22 15.

[0048] One of the features of the invention is that the stator blades 20 are distributed in doublets of blades within assemblies 21 specific to the invention, each intended to be set in incidence within the rectifier, via the control system 22. The assemblies 21 follow each other circumferentially, like the blades within a conventional rectifier 20, with the difference that these blades are here grouped in doublets within the assemblies 21.

[0049] With reference to Figures 2 to 4, each assembly 21 comprises a first platform 50, or radially internal platform, and a second platform 52, or radially external platform. Each of the two platforms 50, 52 has a general disk shape, possibly truncated. The second platform 52 is housed in a recess 53 formed on the inner surface of the outer housing 16, while the first platform 50 is housed in a recess 51 formed on the outer surface of an inner housing 15 of the rectifier 18a, also having the preferred form of a ferrule centered on axis 2. Housing the platforms 50, 52 in the recesses 51, 53 allows these platforms to remain flush or substantially flush with the two AP

[0050] Radial delimitation surfaces of the main vein 14a. Indeed, each of the platforms 50, 52 also participates in the radial delimitation of the main vein 14a. Each assembly 21 also comprises two stator blades 20, arranged adjacently circumferentially and substantially parallel. Each of them has a blade root attached to the first platform 50, and a blade tip attached to the second platform 52.

[0051] Each assembly 21 defines an angle of incidence axis 58 of the assembly, which corresponds to the axis around which the assembly 21 is rotated relative to the two housings 15, 16, so as to achieve the desired angle of incidence for the blade pair 20. The two stator blades 20 of this assembly 21 are then preferentially arranged on either side of this angle of incidence axis 58. Furthermore, the angle of incidence axis 58 is preferably located closer to a leading edge of the two blades than to a trailing edge of these two blades. By moving this rotation axis 58 upstream relative to the blades 20, the difference in angle of incidence between the two blades of the pair 15 is advantageously reduced as the angle of incidence increases. Moving this rotation axis 58 as far upstream as possible, towards the leading edge of the blades, allows for greater precision of the angle at this point.

[0052] Radially inwards, the first platform 50 is extended radially inwards by a first rotating guide journal 34, received in a guide orifice 20 of the assembly 21 made in the inner housing 15. This guide orifice opens radially outwards into the recess 51 receiving the first platform 50. Similarly, the second platform 52 is extended radially outwards by a second rotating guide journal 36, received in a guide orifice of the assembly 21 made in the outer housing 16. This guide orifice opens radially inwards into the recess 53 receiving the second platform 52.

[0053] Bushings can be interposed between the trunnions 34, 36 and their respective guide holes, in order to facilitate rotation during changes in incidence of the blade doublet assemblies 21.

[0054] The second trunnion 36 includes a rotational guide portion 36a, which is received 30 in the guide orifice, and it also includes, at its radially external end, 51787 AP

[0055] a rotating drive portion 36b intended to cooperate with the control system. The two portions 36a, 36b of each second trunnion 36 are centered on the incidence alignment axis 58, and separated from each other by a shoulder.

[0056] Each assembly 21 is preferably made from a single piece, that is to say, from 5 materials. This single piece is for example cast, machined, additively manufactured from one or more metallic materials, or made from composite material, preferably with an organic matrix.

[0057] A composite material fabrication is adopted for the outer casing 16, and possibly also for the inner casing 15. Just as for the assemblies 21, the composite material for the fabrication of the outer casing 16 is preferably of the type comprising glass and / or carbon fibers and a thermosetting or thermoplastic matrix.

[0058] Conventionally, the control system 22 first includes a fixed part consisting essentially of a housing 24, fixedly mounted on the outer surface 15 of the outer casing 16. This housing 24 serves for the articulation of control horns, as will be detailed below.

[0059] The control system 22 also includes levers 28, each of which cooperates with the rotating drive portion 36b of one of the blade doublet assemblies 21. The levers 28 are themselves controlled by a synchronized control ring, allowing the simultaneous adjustment of the assemblies 21 of the same stator. Thus, the first stator 18a is associated with a first control ring 30a centered on the axis 2 and connected to the set of levers 28 controlling the assemblies 21 of the first stator, while the second stator 18b is associated with a second control ring 30b also centered on the axis 2, and connected to the set of levers 28 25 controlling the blades of the second stator.

[0060] The control system 22 also includes a first connecting rod-shaped output member 32a, controlling the rotation of the first ring 30a around the axis 2, while the second connecting rod-shaped output member 32b controls the rotation of the second ring 30b, also around the axis 2.51787 AP 9

[0061] The two connecting rods 32a, 32b are respectively controlled by two puppets 34a, 34b articulated on the housing 24 of the system, in a known manner which will not be further detailed.

[0062] Finally, it is noted that the actuator of the control system 22 can be electric, and that the 5 synchronized control rings 30a, 30b are preferably made of composite material, of the same type as those mentioned previously.

[0063] Of course, various modifications can be made by a person skilled in the art to the invention just described, only as non-limiting examples.

[0064] 10

Claims

51787 AP DEMANDS 1. Aircraft turbomachine (1) comprising a compressor (4, 6), the compressor preferably being a low-pressure compressor, and comprising at least one rectifier 5 (18a, 18b), the rectifier comprising an inner casing (15) and an outer casing (16), as well as a plurality of circumferentially successive assemblies (21), each assembly being intended to be set in angle of incidence within the rectifier (18a, 18b) and comprising a first platform (50) cooperating with the inner casing (15), and a second platform (52) cooperating with the outer casing (16), the rectifier also comprising a control system (22) for setting the angle of incidence of these assemblies (21), characterized in that each assembly also comprises two stator blades (20) each having a blade root integral with the first platform (50), as well as a blade tip integral with the second platform (52),the assembly comprising a first rotational guide trunnion (34) integral with the first platform (50), and a second rotational guide trunnion (36) integral with the second platform (52), and in that the external casing (16) is made of composite material.

2. Turbomachine according to claim 1, characterized in that the first and second platforms (50, 52) of each assembly each have a general disk shape. 20 3. Turbomachine according to claim 1 or 2, characterized in that each assembly defines an angle-of-attack axis (58) of the assembly, the two stator blades (20) being preferably arranged on either side of this angle-of-attack axis (58).

4. Turbomachine according to the preceding claim, characterized in that the angle-of-attack axis (58) of the assembly is located closer to a leading edge of the two stator blades than to a trailing edge of these two blades.

5. Turbomachine according to any one of the preceding claims, characterized in that the second rotation guide trunnion (36) comprises a rotation guide portion (36a), and, at its end, a rotation drive portion (36b).

6. Turbomachine according to any one of the preceding claims, characterized in that each assembly is made of a single piece. 51787 AP 11 7. Turbomachine according to any one of the preceding claims, characterized in that the angle-of-attack control system (22) comprises a synchronized control ring (30a, 30b) made of composite material.

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