Assembly for a turbine engine

Abstract

The invention relates to an assembly (4; 4 ') for a turbomachine (1). 40), comprising a wall (6) and a row of stator blades (10; 100) having a guide surface (8) for guiding an air flow (F1), a row of stator blades extending from the wall and arranged annularly about an axis (A), said surface being inclined with respect to the axis wherein the row of blades comprises a first blade (12) and a second blade (14), the first blade extending substantially perpendicular to the axis and the second blade extending substantially perpendicular to the guide surface. The invention also relates to an axial turbomachine comprising a low-pressure compressor, a high-pressure compressor and a gooseneck-shaped flow channel, the gooseneck-shaped flow channel being arranged axially between the low-pressure compressor and the high-pressure compressor, where the flow channel contains the assembly as described above.

Description

Technical Field

[0001] The present invention relates to the field of turbomachines, and more particularly to the field of axial flow turbomachine compressors. Background Art

[0002] An axial-flow turbomachine generally includes two compressors, a low-pressure compressor and a high-pressure compressor, arranged upstream of a combustion chamber and configured to inhale and compress air to a velocity, pressure and temperature suitable for good combustion.

[0003] In this respect, each compressor comprises a series of compression stages, each compression stage being formed by at least one annular row of rotor blades and at least one annular row of stator blades.

[0004] Directly downstream of the last row of stator blades (which may generally be referred to as "Outlet Guide Vanes (OGVs)") are structural arms (or "struts") that pass through the air flow path of the axial flow turbine.

[0005] The structural arms are usually arranged in ramped ducts (or in gooseneck between compressors), ie the direction of the air flow circulating in the duct is inclined relative to the longitudinal axis of the axial turbine. Document FR 3 027 053 describes an example of a structural arm of this type.

[0006] The OGV vanes typically have an orientation substantially perpendicular to the direction of flow to limit aerodynamic disturbances that would make the flow unstable at the OGV.

[0007] With this orientation of the OGV blades, the few blades circumferentially directly in front of the structural arm have radially outer portions close to the structural arm. The proximity between the trailing edge of the OGV and the leading edge of the arm results in static pressure distortion at the trailing edge of the OGV, resulting in efficiency loss of the turbine.

[0008] To overcome the problem of hydrostatic distortion, there is a solution which consists in moving the OGV axially away from the structural arm. This solution is not justifiable because it increases the axial length of the turbine and therefore the overall weight of the turbine.

[0009] Therefore, there is room for improvement in improving the performance of compressors without affecting the size of the compressor. Summary of the invention

[0010] Technical issues

[0011] The present invention aims to solve the drawbacks of the designs of turbomachine compressors of the prior art. In particular, the present invention aims to propose a solution that makes it possible to limit the aerodynamic disturbances at the stator blades located upstream of the structural arms and, at the same time, to limit the static pressure distortion phenomena, in particular in the ramp flow channel, without complicating the compressor of the turbomachine and / or adding additional weight to the compressor of the turbomachine.

[0012] Technical Solution

[0013] The invention relates to a component for a turbomachine, comprising a wall and a row of stator blades, the wall having a guide surface for guiding an air flow, the row of stator blades extending from the wall and being arranged annularly around an axis, the surface being inclined relative to the axis, wherein the row of blades comprises a first blade and a second blade, the first blade extending substantially perpendicularly to the axis and the second blade extending substantially perpendicularly to the guide surface.

[0014] Preferably, the inclination of the guide surface relative to the axis results in the air flow having the same inclination.In this configuration, the wall of the turbine has a curved profile in longitudinal section and the wall of the turbine forms an oblique angle with the longitudinal axis of the turbine.

[0015] The term "annularly extending row of blades" refers to individual rings of blades which are arranged circumferentially one behind the other and which define inter-blade spaces through which the air flows.

[0016] According to an advantageous embodiment of the invention, the assembly further comprises a structural arm arranged axially just downstream of the row of blades, an inter-arm space being defined between two circumferentially adjacent structural arms, the first blade circumferentially overlapping the structural arm and the second blade circumferentially overlapping the inter-arm space.

[0017] According to an advantageous embodiment of the invention, the row of blades is formed by a first set of blades and a second set of blades, the first set of blades and the second set of blades alternating circumferentially.

[0018] Advantageously, the circumferential alternation of the first and second sets of blades makes it possible to minimize aerodynamic disturbances by promoting the guidance of the air flow other than through the trailing edges of the row of blades.

[0019] Furthermore, the manufacture of the row of blades and the assembly of the row of blades (in particular the assembly of the row of blades to an angular sector of the turbine) are simplified.

[0020] According to an advantageous embodiment of the invention, each first blade set comprises between 3 and 8 blades, preferably 4 blades.

[0021] According to an advantageous embodiment of the invention, each second blade set comprises between 4 and 10 blades, preferably 5 blades.

[0022] According to a preferred embodiment of the invention, the row of blades further comprises a plurality of third blades which are regularly arranged circumferentially between the first blade and the second blade, the third blades having a corresponding orientation ranging from an orientation perpendicular to the axis of the first blade to an orientation perpendicular to the guide surface of the second blade, but excluding an orientation perpendicular to the axis of the first blade and an orientation perpendicular to the guide surface of the second blade.

[0023] Advantageously, the third blade makes it possible to further smooth the air flow at the trailing edge of the row of blades, thus promoting the regularity and progression of the air flow in the flow channel.

[0024] According to a preferred embodiment of the present invention, the corresponding orientation of the third blade gradually changes according to the circumferential position of the third blade relative to the first blade and the second blade. The closer the third blade is to the first blade in the circumferential direction, the closer the orientation of the third blade is to the orientation of the first blade. The closer the third blade is to the second blade in the circumferential direction, the closer the orientation of the third blade is to the orientation of the second blade.

[0025] According to an advantageous embodiment of the invention, the third blades have respective orientation angles which gradually vary by at least 0.5°.

[0026] According to an advantageous embodiment of the invention, the progression of the orientation of the third blade, seen in radial cross section, has a triangular profile.

[0027] According to an advantageous embodiment of the invention, the progression of the orientation of the third blade, seen in radial cross section, has a sinusoidal profile.

[0028] According to an advantageous embodiment of the invention, the trailing edge of the first blade is at a first distance from the leading edge of the structural arm in the direction of the air flow, and the trailing edge of the second blade is at a second distance from the leading edge of the structural arm in the direction of the air flow, wherein the first distance is greater than the second distance.

[0029] According to an advantageous embodiment of the invention, all blades have the same chord length. Preferably, the blades have the same average chord over the entire span of the blade. This makes it possible to facilitate the control of any distortion of the static pressure, in particular by limiting the static pressure to the level of the entire span of the leading edge of the structural arm.

[0030] According to an advantageous embodiment of the invention, the guide surface for guiding the air flow forms an angle of inclination with the axis of between 10° and 60°.

[0031] The invention further relates to an axial flow turbomachine comprising a low-pressure compressor, a high-pressure compressor and a gooseneck flow passage arranged axially between the low-pressure compressor and the high-pressure compressor, wherein the flow passage contains the assembly according to the invention.

[0032] Advantages of the present invention

[0033] The invention is particularly advantageous in that it makes it possible to limit aerodynamic disturbances of the stator blades in a ramped air flow channel, in particular due to their radial orientation or orientation perpendicular to the turbine axis, thus improving the overall stability of an annular row of stator blades.

[0034] Furthermore, the hydrostatic distortion phenomenon is reduced by moving the radial stator blades away from the leading edge of the structural arm without changing the axial position of the row of stator blades in the air flow path.

[0035] Thus, a good compromise is obtained to improve the flow downstream of the radial blades and downstream of the inclined blades.

[0036] In this configuration, pressure losses are limited and compressor operability is increased, which advantageously improves compressor performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A simplified partial view of an axial flow turbine is shown;

[0038] Figure 2 is a schematic diagram of a longitudinal cross-sectional view of a flow channel of an axial turbine including an assembly according to the invention;

[0039] Figure 3 The first embodiment and Figure 1 A radial cross-sectional view of an assembly of;

[0040] Figure 4 The second embodiment and Figure 2 A radial cross-sectional view of an assembly. DETAILED DESCRIPTION

[0041] In the following description, the terms "inboard", "inner", "outer side" and "outer" refer to positioning relative to the longitudinal rotation axis of the turbomachine. The axial direction corresponds to the direction along the longitudinal rotation axis of the turbomachine. The radial direction is perpendicular to the longitudinal axis. The annular or circumferential direction is generally a circular direction around the longitudinal axis. Upstream and downstream refer to the flow direction of the axial air flow in the main flow channel of the turbomachine.

[0042] The drawings schematically show the elements and are not drawn to scale. In fact, the drawings have been intentionally simplified to facilitate understanding, and some dimensions have been exaggerated to facilitate reading.

[0043] Figure 1A simplified partial view of an axial turbomachine 1 is shown. In this particular case, the axial turbomachine 1 is a twin-flow turbojet, but it may also be a turbojet, a turbofan, a turboprop, a turbine engine or any other turbomachine. A person skilled in the art will understand that the invention may also be applied to a turbomachine having a centrifugal compressor.

[0044] The turbomachine 1 comprises a first compression stage, known as the low-pressure compressor 3 , a second compression stage, known as the high-pressure compressor 5 (partially shown), as well as a combustion chamber and one or more turbine stages (not shown).

[0045] In operation, the mechanical power of one or more turbines transmitted to the rotors via a central shaft moves the rotors of the two compressors 3 and 5. Thus, the rotation of the rotors about their longitudinal axis of rotation A enables the generation and progressive compression of an air flow up to the inlet of the combustion chamber.

[0046] An intake fan, usually referred to as a fan or blower, is coupled to the rotor and generates an incoming air flow F. The blower is arranged upstream of a separation nozzle 11, which is capable of dividing the incoming air flow F into a radially inner air flow (referred to as air flow F1 or mainstream F1) and a radially outer air flow (referred to as secondary flow F2), the air flow F1 or mainstream F1 circulates in the main flow channel 2 and passes through each of the aforementioned stages of the turbine 1, and the secondary flow F2 passes through an annular duct along the turbine and then merges with the mainstream F1 at the turbine outlet. The secondary flow F2 can be accelerated to generate the reverse thrust required for the flight of the aircraft.

[0047] Preferably, the flow passage 2 has a gooseneck shape, commonly known as a ramp flow passage, and preferably, the low-pressure compressor 3 comprises, in its downstream half, an assembly 4, 40, which will be described in full detail in this specification.

[0048] Figure 2 is a schematic diagram of a longitudinal cross-sectional view of an axial turbine flow channel 2 including the components 4 , 40 .

[0049] refer to Figure 2 The flow channel 2 enables the main flow F1 to be guided between an outer wall 6 having an outer air guiding surface 8 and an inner wall 9 having an inner guiding surface 7 .

[0050] The assembly 4 , 40 comprises a row of stator blades 10 , 100 (also called stator cascade or OGV) extending from the outer wall 6 to the inner wall 9 and extending annularly around the longitudinal axis A of the axial turbine. The second guide wall 9 may be an inner shroud 9 , for example.

[0051] Preferably, the height of the flow channel 2 (ie the radial distance between the guide surface 8 and the inner shroud 9) is constant, rather than the height of the assembly 4, 40.

[0052] The wall 6, in particular the guide surface 8, is inclined relative to the axis A. In this respect, a straight line tangent to the guide surface 8 on the right side of the row of stator blades 10, 100 has an inclination angle α of between 5° and 80°, preferably between 10° and 60°, relative to the axis A. The inclination along the angle α results in the air being directed along the inclination of the downward slope, resulting in an overall inclination of the direction of the main flow F1 relative to the axis A on the right side of the assembly 4, 40.

[0053] This row of stator blades 10, 100 may belong to a low-pressure compressor of an axial turbine, for example, and may consist of the following components:

[0054] a blade referenced 12 and subsequently called “first blade”, the first blade extending substantially perpendicularly to the axis A; and

[0055] A blade referenced 14 and called “second blade” hereinafter, which extends substantially perpendicularly to the guide surface 8 .

[0056] Preferably, the first blade 12 and the second blade 14 have the same chord length and / or average profile chord length, particularly where the chord varies over the overall extent of each blade.

[0057] The second blade 14 has an inclination angle relative to the axis A corresponding to an angle α+90°.

[0058] The assembly 4 , 40 also comprises a structural arm 16 arranged axially just downstream of the row of stator blades 10 , 100 .

[0059] Along the direction of the air flow F1 and preferably along the projection on the guide surface 8, the trailing edge 13 of the first blade 12 is at a first distance D from the leading edge 17 of the structural arm 16, and the trailing edge 15 of the second blade 14 is at a second distance d from said leading edge 17. Here, "distance" is given its usual definition, i.e. the shortest distance between two bodies.

[0060] Preferably, the trailing edge 13 of the first blade 12 is axially at the same level as the trailing edge 15 of the second blade 14, at the level of the inner shroud 9, and more precisely at Figure 2 At the level of the indicated point P. To this end, the trailing edge 15 of the second blade 14 does not extend axially beyond the trailing edge 13 of the first blade 12 in the flow direction of the air flow F1 .

[0061] The first distance D is greater than the second distance d. Advantageously, this makes it possible to avoid axial separation of the entire row of blades 10, 100 relative to the leading edge 17 of the structural arm 16, while preventing the radially outer portion of the first blade from being too close to the arm. The distortion of the flow can be limited by avoiding static pressure loss phenomena at the structural arm 16.

[0062] Figure 3 The first embodiment and Figure 2 A radial cross-sectional view of component 4.

[0063] refer to Figure 3 The structural arms 16 define an inter-arm space 18 between every two circumferentially adjacent structural arms 16 .

[0064] In this configuration, a group 12 ′ formed by a plurality of first blades 12 (referred to as a first group 12 ′) circumferentially overlaps the structural arm 16 , while a second group 14 ′ formed by the second blades 14 circumferentially overlaps the inter-arm space 18 , which is partially covered by the second blades 14 .

[0065] In this respect, the row of stator blades 10 is formed by a first group 12' and a second group 14' which are arranged circumferentially around the axis of the turbine (ie according to Figure 3 horizontal orientation) alternately.

[0066] Preferably, in order to replace the blades of the stator blade row 10 and maximize stability, the first group 12' comprises 2 to 10 blades, preferably 3 to 8 blades, even more preferably 4 blades, and the second group 14' comprises 2 to 12 blades, preferably 4 to 10 blades, even more preferably 5 blades.

[0067] In particular, Figure 3 As can be seen in FIG. 1 , the second blade 14 can be axially (in Figure 3 ) is closer to arm 16.

[0068] Figure 4 The second embodiment and Figure 2 A radial cross-sectional view of assembly 40 .

[0069] In fact, Figure 4 In particular, it shows Figure 2 Schematic diagram of the progression of the orientation of the stator blade 100 .

[0070] refer to Figure 4 The row of stator blades 40 includes, in addition to the first blades 12 and the second blades 14 , a plurality of third blades 30 , which are circumferentially arranged between the first blades 12 and the second blades 14 .

[0071] It should be noted that the third blade 30 is not visible and therefore not shown in FIG. Figure 2 Shown in.

[0072] The third blade 30 has a corresponding orientation that is between the orientation of the first blade 12 and the orientation of the second blade 14 , but does not include the orientation of the first blade 12 and the orientation of the second blade 14 .

[0073] The respective orientations of the third blades 30 change gradually and regularly according to the circumferential positions of the third blades 30 relative to the first blades 12 and the second blades 14 .

[0074] In this configuration, the progressive orientation of the stator blades 100 is primarily due to the progression of the orientation of the third blade 30 between the extreme ends (ie, the first blade 12 and the second blade 14 ).

[0075] In this regard, the closer the third blade 30 is circumferentially to the first blade 12, the closer the orientation of the third blade 30 will be to the orientation of the first blade 12. In fact, the closer the third blade 30 is annularly to the first blade 12, the closer the orientation of the third blade 30 will be to the inclination of the first blade 12.

[0076] Similarly, the closer the third blade 30 is to the second blade 14 in the circumferential direction, the closer the orientation of the third blade 30 is to the orientation of the second blade 14 .

[0077] Preferably, the third blades 30 have respective orientation angles that gradually vary by at least 0.5°, and / or the variation in the angle of the third blades 30 is preferably less than 20°.

[0078] The variation of the orientation of the third blades is regular and thus correlated with the number of third blades.

[0079] The progression of the orientation of the third blade 30 with a triangular profile 22 and / or a sinusoidal profile 20 makes it possible to further smooth the air flow and avoid aerodynamic disturbances (eg due to angular effects or sudden changes in the flow guiding surface).

[0080] In summary, the difference between the first and second embodiments of the invention results in a circumferential evolution of the inclination of the blades forming the stator cascade.

[0081] All blades according to the first and second embodiments of the invention, in particular those blades circumferentially adjacent to the structural arm, can have a setting or orientation also called "tilt", which makes it possible to have different blade profiles at the stator blade cascade in order to homogenize the pressure values ​​at the leading edges of the blades forming the stator blade cascade as much as possible. The "tilt" can be adjusted independently for each blade.

[0082] Furthermore, the elimination of the static pressure distortion phenomenon at the leading edges of the blades of the stator cascade can also be achieved by spacing the blades located annularly adjacent to the structural arm more circumferentially, said spacing involving all blades of the first or second embodiment.

[0083] It should be noted that the present invention is not limited to the examples described in the figures. The teachings of the present invention may be particularly applicable to another type of turbine, and each technical feature of each of the examples shown is applicable to other examples. For example, a row of stator blades may consist of Figure 3 Part of row 10 with Figure 4 A combination of a portion of the row 100 is produced.

Claims

1. A component (4; 40) for a turbine (1), comprising a wall (6) and a row of stator blades (10; 100), the wall having a guide surface (8) for guiding an air flow (F1), the row of stator blades extending from the wall (6) and arranged annularly around an axis (A), the surface (8) being inclined relative to the axis (A), the component (4; 40) being characterized in that the row of blades (10; 100) comprises a first blade (12) and a second blade (14), the first blade extending substantially perpendicularly to the axis (A) and the second blade extending substantially perpendicularly to the guide surface (8).

2. The assembly (4; 40) according to claim 1, characterized in that The assembly further comprises a structural arm (16) which is axially arranged just downstream of the row of blades (10; 100), an inter-arm space (18) being defined between two circumferentially adjacent structural arms (16), the first blade (12) circumferentially overlapping the structural arm (16), and the second blade (14) circumferentially overlapping the inter-arm space (18).

3. The assembly (4) according to claim 1 or 2, characterized in that The row of blades (10) is formed by a first blade group (12') and a second blade group (14'), the first blade group (12') and the second blade group (14') alternating circumferentially.

4. The assembly (4) according to claim 3, characterized in that Each first blade group (12') comprises between 3 and 8 blades (12), preferably 4 blades (12).

5. Assembly (4) according to claim 3 or 4, characterized in that Each second blade group (14') comprises between 4 and 10 blades (14), preferably 5 blades (14).

6. The assembly (40) according to claim 1 or 2, characterized in that The row of blades (100) further comprises a plurality of third blades (30), the third blades being regularly arranged circumferentially between the first blade (12) and the second blade (14), the third blades (30) having a corresponding orientation, the corresponding orientation being between an orientation perpendicular to the axis (A) of the first blade (12) and an orientation perpendicular to the guide surface (8) of the second blade (14), but excluding an orientation perpendicular to the axis of the first blade and an orientation perpendicular to the guide surface of the second blade.

7. The assembly (40) according to claim 6, characterized in that The corresponding orientation of the third blade (30) gradually changes according to the circumferential position of the third blade (30) relative to the first blade (12) and the second blade (14); the closer the third blade is to the first blade in the circumferential direction, the closer the orientation of the third blade (30) is to the orientation of the first blade (12); and the closer the third blade is to the second blade in the circumferential direction, the closer the orientation of the third blade (30) is to the orientation of the second blade (14).

8. The assembly (40) according to claim 7, characterized in that The third blades (30) have respective orientation angles that gradually change by at least 0.5°.

9. The assembly (40) according to claim 8, characterized in that The progression of the orientation of the third blade (30) has a triangular profile (22) as seen in radial cross section.

10. The assembly (40) according to claim 7, characterized in that The progression of the orientation of the third blade (30) has a sinusoidal profile (20) seen in radial cross section.

11. Assembly (4; 40) according to any one of claims 2 to 10, characterized in that The trailing edge (13) of the first blade (12) is at a first distance (D) from the leading edge (17) of the structural arm (16) along the direction of the air flow (F1), and the structural arm is axially arranged directly downstream of the row of blades (10; 100); the trailing edge (15) of the second blade (14) is at a second distance (d) from the leading edge (17) of the structural arm (16) along the direction of the air flow (F1), and the first distance (D) is greater than the second distance (d).

12. Assembly (4; 40) according to any one of claims 1 to 11, characterized in that All blades (12, 14, 30) have the same chord length.

13. Assembly (4; 40) according to any one of claims 1 to 12, characterized in that The guide surface (8) for the air flow (F1) forms an inclination angle (α) with the axis (A) comprised between 10° and 60°.

14. An axial-flow turbine (1), comprising a low-pressure compressor (3), a high-pressure compressor (5) and a gooseneck flow channel (2), wherein the gooseneck flow channel is axially arranged between the low-pressure compressor (3) and the high-pressure compressor (5), the turbine being characterized in that the flow channel (2) includes a component (4; 40) according to any one of claims 1 to 13.

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