Compressor module for turbomachine

Abstract

The invention relates to a turbomachine compressor module (47) comprising an annular row of struts (46) provided with pivotable flaps (60). The struts (46) can define an inter-strut space (56) between two circumferentially adjacent struts (46, 48), in which inter-strut space (56) stator vanes (39) with variable orientation are at least partially arranged. The invention also relates to a turbomachine provided with such a module (47) and a row of rotor blades (40) directly downstream of the module.

Description

TECHNICAL FIELD

[0001] The present invention relates to an assembly for a turbomachine. More particularly, the present invention relates to a compressor casing module comprising radial struts and stator vanes. BACKGROUND

[0002] An axial turbomachine compressor casing can comprise a structural part essentially consisting of an outer ring, a central hub and structural arms, usually called "struts", extending mainly radially between the hub and the ring. The structural casing forms the support structure of the turbomachine. It is usually in the form of a single piece casting and it can define a swan neck shaped airflow passage.

[0003] The upstream and downstream of the swan neck passage are usually positioned with two rows of annular stator vanes.

[0004] An example of such a structural casing is described in FR 3 027 053 Al.

[0005] A large gap is left between the struts and the row of stator vanes directly downstream of the struts. This gap is a source of pressure drop because the flow in the strut wake is not ideally controlled to properly meet the leading edge of the stator vanes. There is therefore an opportunity to improve the performance of the compressor. SUMMARY

[0006] The object of the present invention is to eliminate any pressure drop at the interface between the structural struts and the row of stator vanes directly downstream of these struts, thereby improving the performance of the compressor.

[0007] The present invention relates to a turbomachine compressor module comprising: a substantially axisymmetric central hub; an outer ring coaxial with the central hub; and a row of annular struts extending from the central hub to the outer ring, notably each strut having a fixed upstream portion and a pivotable downstream flap.

[0008] The integration (in the sense of "positioning") of the deflection flow vanes in the struts makes it possible to avoid the above-mentioned pressure losses in the known compressors. In addition, these losses are also affected by the size of the struts, which usually receive services such as oil or fuel pipes or electrical cables or possibly radial drive shafts.

[0009] According to the invention, the module comprises a row of annular variable orientation stator vanes extending from the central hub to the outer ring, the struts defining, between two circumferentially adjacent struts, an inter-strut space, and the stator vanes being at least partially disposed in the inter-strut space. The incorporation of axially overlapping stator vanes between the struts further allows the entire row of stator vanes to advance and thus reduce the overall length of the turbomachine. This makes the turbomachine more compact and lighter.

[0010] According to an advantageous embodiment of the application, the upstream portion has a cavity open towards the downstream side, the cavity forming part of a cylinder, the flap being received in said cavity. This arrangement allows continuity of the air guiding surface, thus limiting the pressure loss at the fixed portion / flap interface.

[0011] According to an advantageous embodiment of the application, the annular row of stator vanes is a first row and the module further comprises a second annular row of stator vanes arranged in the inter-pier space and axially distant from the first row of vanes. The positioning of the rows of vanes initially upstream and downstream of the piers in the inter-pier space further improves the compactness and the weight of the turbomachine.

[0012] According to an advantageous embodiment of the application, the upstream portion of each pier is symmetrical with respect to an axis parallel to the hub axis. The advantage of this geometry is that it is neutral for the flow upstream of the pier without tangential component.

[0013] According to an advantageous embodiment of the application, the vanes and the flap have respective trailing edges sharing one common axial position. In other words, the flap and the stator vanes, or at least their downstream ends, are axially aligned. This arrangement allows a circumferentially uniform flow.

[0014] According to an advantageous embodiment of the application, the central hub comprises a radially outer air flow guiding surface, the air flow guiding surface being oriented in line with the flap at an angle of between 0° and 10° with the axis of symmetry of the central hub. This inclination of the air guiding surface is small enough to limit the loss of load on the inner portion of the vanes and flap, which can deviate from the guiding surface at some angular positions thereof.

[0015] According to an advantageous embodiment of the application, the flap has a respective cross section substantially identical to that of the vanes. By "cross section" is meant here the profile in a cross section, for example the profile in a plane perpendicular to the trailing edge at a given point of the trailing edge. Thus, at the outlet of the module, the flow is more uniform.

[0016] According to an advantageous embodiment of the application, a common actuation mechanism controls the orientation of the vanes and the pivoting movement of the flap. This solution simplifies the driving of the flap and the vanes. Alternatively, two independent mechanisms can be provided to orient the stator vanes or some vanes in one orientation and the flap in another orientation.

[0017] The application also relates to a turbomachine comprising a low-pressure compressor and / or a high-pressure compressor, provided with a module according to one of the above embodiments, the turbomachine comprising a row of rotor blades directly downstream of the module.

[0018] Thus, the pressure drop between the structural piers and the row of stator vanes directly downstream of the piers is eliminated. Attached Figure Description

[0019] Figure 1 A turbine according to the prior art is shown;

[0020] Figure 2 An axial-flow turbine according to the present invention is shown;

[0021] Figure 3 The compressor module according to the invention is depicted in a section perpendicular to the turbine axis;

[0022] Figure 4 A partial view of the module according to the invention, viewed radially from the outside, is shown;

[0023] Figures 5A-6B Two alternatives for the structural support are shown;

[0024] Figure 7 A partial view of a module according to another embodiment of the present invention, viewed radially from the outside, is shown;

[0025] Figure 8 A partial view of the module as seen from the side is shown, with its radial extent shown in a longitudinal section. Detailed Implementation

[0026] In the following description, the terms "internal" and "external" refer to positions relative to the axis of rotation of the turbine. The axial direction is along the axis of rotation of the turbine, which coincides with the axis of symmetry of the hub of the housing module. The radial direction is perpendicular to the axis of rotation. Upstream and downstream refer to the primary flow directions of the fluid within the turbine. The term "whole" should be understood as the entirety in rotation.

[0027] Figure 1 This is a simplified representation of an existing axial-flow turbine. This is a dual-flow turbojet engine.

[0028] The turbine 2 has a rotation axis 4. An annular inlet 6 is divided into a main flow path 8 and a secondary flow path 10 by a circular separating nozzle 12. The main flow 14 and the secondary flow 16 pass through these flows 8 and 10 respectively and meet at the outlet of the turbine 2. The main flow 14 and the secondary flow 16 are coaxial annular flows and cooperate with each other. They are guided by the inner and outer walls of the turbine 2.

[0029] The secondary flow 16 is accelerated by a fan 18 located at inlet 6 to generate thrust for the aircraft's flight. A straightening guide vane 20 can be arranged in the secondary flow path 10 and can be configured to increase the axial component of the secondary flow velocity vector. The fan 18 is located upstream of the main duct 8 and the secondary duct 10.

[0030] The turbomachine 2 comprises a compression zone formed by two compressors 24, 26, a combustion chamber 22 and expansion zones 28, 32. The compressors 24, 26 consist of a low pressure compressor 24 and a high pressure compressor 26.

[0031] The high pressure compressor 26 can be located at the inlet of the combustor 22.

[0032] Downstream of the combustor 22, the turbomachine 2 can have a high pressure turbine 28 coupled to the high pressure shaft 30, and a low pressure turbine 32 coupled to the low pressure shaft 34. The latter can rotate independently of the high pressure shaft 30. These turbines 28, 32 can form the expansion zones of the main flow 14.

[0033] In operation, the mechanical power received by the turbines 28, 32 is transmitted to the shafts 30, 34 which set the compressors 24, 26 in motion. The compressors have a plurality of rows of rotor blades associated with a plurality of rows of stator vanes. The rotor blades are driven by the shafts 30, 34 around the rotation axis 4 to produce a flow of air and progressively compress it to the inlet of the combustion chamber 22.

[0034] The turbomachine can comprise a gear device, for example a gearbox 36, which drives the fan 18 at a lower speed than the rotor blades. The low pressure compressor 24 or booster is referred to here as "fast". With the gearbox 36, only two turbomachines are needed to drive the compressors and the fan at three different speeds.

[0035] In this example, the low pressure compressor 24 comprises two rows of rotor blades 40, 42 connected to the shaft 34 by a rotor 44.

[0036] The compressor 24 comprises stator vanes 39, 41 interposed between the rotor blades 40, 42.

[0037] The compressor 24 can comprise alternating stator vanes and rotor blades, or, as in the example shown, two rows of consecutive stator vanes 43, 45 in its downstream part. This set of stator vanes 39, 41, 43, 45 forms the rectifier 35 of the compressor 24.

[0038] The stator of the turbomachine 2 can comprise a plurality of support casing modules, including an upstream module 47 and a downstream module 49 arranged on either side of the compressor 24. These modules 47, 49 can comprise annular sleeves forming part of the main duct 8, and can have struts 46, 48 extending radially through the duct 8. The annular sleeves can have a gooseneck profile. They can mark a significant reduction in the diameter of the main duct 8.

[0039] The upstream module 47 and its struts 46 can support the gearbox 36.

[0040] Upstream of the struts 46 is a row of stator vanes 37 close to the nozzle 12. Downstream of the struts 48 is the high pressure compressor 26 with stator vanes 50 and rotor blades 52. The latter are driven in rotation by the shaft 30.

[0041] Typically, multiple rows of stator vanes are arranged directly upstream and downstream of the struts 46, 48 such that the air flows through the inter-strut space with a velocity vector that has no tangential component. These rows can or can not be variable stator vane rows, i.e. their orientation around a substantially radial axis is adjustable. These vanes are supported by external and internal shrouds downstream or upstream of the structural casings 47, 49.

[0042] Figure 1 The upper right side of Fig. 1 shows an enlarged view of the inlet of the high pressure compressor 26. In particular, it shows a series of rows of annular struts 48 in the direction of air flow, followed by a row of annular stator vanes 50, the orientation of which is variable by means of a device 51. A row of rotor blades 52 is also shown downstream of the variable stator vanes 50 and is the most upstream row of rotor of the high pressure compressor 26.

[0043] Figure 2 A turbomachine according to the invention is shown.

[0044] The design differs from turbomachines known in the prior art mainly in the design of the modules 47 and 49. Either or both of the structural modules 47, 49 can comprise structural struts 46, 48 with a fixed upstream portion 58 and a pivoted downstream portion or flap 60.

[0045] Optionally, as shown in Figure 2 at least one row of stator vanes 37, 39, 45, 50 is arranged in axial overlap with the structural struts 46, 48.

[0046] Thus, as can be seen from a comparison between the length of the turbomachine in Figure 2 and Figure 1 (see the mixing lines in the lower right and Figure 1 upper right), the integration of stator vanes into the modules increases the overall length of the turbomachine. Figure 2

[0047] Figure 2 The vanes 37 are shown partially overlapping the struts 46 and the vanes 39 are fully integrated between the struts 46. Alternatively, the vanes 39 can only partially be in axial flush with the struts 46 and / or the vanes 37 can be upstream of the struts 46.

[0048] ​In addition or alternatively to this, the struts 48 of the module 49 can be modified in the same way. The inset in the enlarged view shows the variable stator vanes 50 at the inlet of the high pressure compressor 26 (which are hidden by the struts 48). The rotor blades 52 can thus be placed directly downstream of the struts 48.

[0049] Figure 3 A cross-sectional view of the module 47 or 49 perpendicular to the axis 4 is shown. The module 47, 49 consists of the struts 46 or 48, the vanes 37, 39 or 45, the hub 53 and the outer ring 55. In the following description, reference will be made to the reference numerals relating to the module 47. The skilled person will understand that the same teaching can be applied to the module 49, alternatively or in combination.

[0050] The struts 46 define a strut-to-strut space 56 circumferentially between two adjacent struts 46.

[0051] For the sake of clarity, Figure 3 Only three vanes 39 in a strut-to-strut space 56 are shown. Several and preferably all strut-to-strut spaces 56 accommodate the same or different number of vanes 39, preferably distributed evenly circumferentially.

[0052] The central hub 53 has an outer surface 53.1 which can be substantially conical. The outer surface 53.1 can also be curved or even have an inflection point, so that the gas flow through the module 47 resembles a "gooseneck". The upstream diameter of the hub 53 is greater than its downstream diameter.

[0053] The struts 46 are preferably evenly distributed angularly around the central hub 53. Alternatively, more struts 46 or struts of greater circumferential thickness can be provided at key locations, in particular for accommodating fluid lines.

[0054] The various parts of the module 47 can be connected together by welding, for example laser or electron beam welding.

[0055] The vanes, in particular the vanes 39, integrated in the module 47 can be rotated around an axis A corresponding to each vane, which is shown here as a radial axis. An actuation mechanism (not shown) common to all vanes, for example a ring and a series of connecting rods, allows the vanes to be rotated around their axis A.

[0056] The vane orientation actuation mechanism can be of the kind shown in EP 3 361 058 A1, for example. Several actuation mechanisms in the form of independent coaxial synchronous rings allow the vanes to be rotated to different angles.

[0057] The struts 46, 48 generally extend along a B axis corresponding to each strut 46, 48. The B axis is shown here as radial and perpendicular to the axis 4.

[0058] Figure 4 A partial view of the module 47 along the axis B is shown from an external radial view. The outer surface 53.1 of the hub and the inter strut space 56 between two circumferentially adjacent struts 46 can be seen. The arrow 14 indicates the direction of flow, which is generally axial (parallel to the axis 4) into or out of the compressor.

[0059] Figure 4 The right-hand side shows a portion of the rotor with vanes 40, the arrow indicating the direction of rotation of the rotor.

[0060] The strut 46 has a leading edge 46.1 and a trailing edge 46.2.

[0061] In the inter strut space 56 a guide vane 39 is arranged. In this example, the guide vane 39 is completely enclosed in this space 56. More specifically, the trailing edge 46.2 of the strut is axially aligned with the trailing edge 39.2 of the guide vane 39. The trailing edges 39.2 and 46.2 are preferably identical.

[0062] Alternatively or in combination, the guide vane can be arranged opposite the upstream portion 58 and can have a leading edge aligned with the leading edge 46.1 of the strut (see Figure 7 the guide vane 37 in).

[0063] Due to the integration of the guide vane 39 in the inter strut space, the gas flow 14 can encounter the rotor vanes (see 40 or 52 in ) directly downstream of the module 47. Figure 1

[0064] The strut 46 consists of a fixed upstream portion 58 and a pivotable downstream portion or flap 60. The flap 60 pivots around an axis B which is radial and passes through the strut 46. The pivoting movement of the flap 60 can be controlled by the same actuation mechanism as the mechanism orienting the guide vane 39.

[0065] The B axis can be located at an axial position between 60% and 90% of the chord of the strut.

[0066] The upstream portion 58 can be substantially symmetrical about an axis C which is parallel to the axis 4 of the turbomachine 2.

[0067] In a cross-sectional view perpendicular to the B axis, the flap 60 can have the same profile (cross-section) as the guide vane 39. Alternatively, the profiles can be different.

[0068] The flap 60 extends no more than one third of the axial length of the strut 46.

[0069] The circumferential thickness of the guide vane 39 is such that the guide vane 39 occupies less than 20% of the circumferential span of the inter strut space 56.

[0070] Figure 5A and 5BThe fixed part 58 and the flap 60 in the first embodiment are shown. The fixed part 58 has a cavity 58.1 which has a shape similar to a portion of a cylinder. The flap 60 has a complementary shape and is received in the cavity 58.1. The axis of the cylindrical portion of the cavity 58.1 can coincide with the pivot axis B of the flap 60.

[0071] This arrangement provides continuity of the air guiding surface between the fixed part 58 and the flap 60.

[0072] Figure 6A and 6B A second variant is shown. In this example, the hinge 46.3 is used to connect the flap 60 to the fixed part 58.

[0073] Figure 7 Another example of the housing module 47 is shown.

[0074] A portion of the strut 46.4 is symmetrical with respect to the C axis, the upstream portion 46.5 is symmetrical with respect to the C axis. In this example, the upstream portion 46.6 has a profile corresponding to that of the guide vanes 37, and thus has a lower surface and an upper surface. Here, the guide vanes 37 are entirely arranged in the inter-strut space 56.

[0075] If two rows of stator guide vanes 37, 39 are arranged in the inter-strut space 56, then in this illustration only one row 39 is variable in orientation.

[0076] Figure 8 A partial longitudinal section of the module 47 is shown. The hub 53 comprises a radially outer surface 53.1 which internally delimits the air flow Figure 2 The number 8 in this figure). This surface 53.1 tends to approach the axis 4 in the downstream direction. The flap 60 is shown schematically in dotted line, in a position in which it forms a small angle with the axis 4 (the flow is not deflected or only slightly deflected in tangential direction). The solid line shows the flap 60' in another position, with a greater angle of orientation, thus deflecting the air flow.

[0077] In the position with a large angle, the radially inner point of the trailing edge 46.2 becomes far from the surface 53.1. This gap creates an aerodynamic loss. The same problem occurs with the guide vanes 39, which at certain angular positions are also detached from the surface 53.1.

[0078] It is therefore necessary to provide an arrangement of the surface 53.1, the flap 60 and the guide vanes 39 such that, in unison with the trailing edges 39.2, 46.2 (at all orientation positions of the flap 60 and of the guide vanes 39), the surface 53.1 is inclined with respect to the axis 4 of the turbomachine by no more than 10°. This angular limitation is achieved by Figure 8 the angle a in this figure.

[0079] Alternatively, the hub 53 can have an outer surface 53.1 which is non-axially symmetric and has a substantially flat portion which "follows" the trajectory of the inner edge of the flap 60. In this way, for all orientations of the flap 60, either a constant gap or permanent contact between the flap 60 and the surface 53.1 can be achieved. The same design can be applied to the vanes 39 (in addition to or as an alternative to the flaps).

[0080] It can also be seen from Figure 8 that the axis B is not necessarily exactly radial, for example it can be normal to the surface 53.1. The same applies to the axis A which pivots the vanes 39.

[0081] In fact, in the example shown in the preceding figures, the axes A and B are represented as radial in order to facilitate the representation and understanding of the concept of the present invention. However, the present invention is not limited to purely radial axes A and B, in particular it is possible for the axes A and / or B to be inclined (as Figure 8 shown) or offset (the axes A and / or B do not pass through the axis 4 in Figure 3 ).

[0082] The person skilled in the art will recognize that the different embodiments given here can be combined and the teachings of one embodiment can be applied to all other embodiments.

[0083] Furthermore, the examples shown here show three vanes between two adjacent struts. Other numbers of vanes can be provided, in particular when the struts are irregularly angularly spaced. Advantageously, between 3 and 10 vanes are chosen in each inter-strut space.

Claims

1. A compressor module (47, 49) for a turbomachine (2), comprising: - a substantially axisymmetric central hub (53); - an outer ring (55) coaxial with the central hub (53); - an annular row of struts (46, 48) extending from the central hub (53) to the outer ring (55), each strut (46, 48) of the annular row of struts (46, 48) having a fixed upstream portion (58) and a pivotable downstream flap (60), the struts (46, 48) of the annular row of struts (46, 48) defining an inter-strut space (56) between two circumferentially adjacent struts (46, 48) of the annular row of struts (46, 48); and - an annular row of variable stator vanes (37, 39, 45) extending from the central hub (53) to the outer ring (55), the variable stator vanes (37, 39, 45) of the row being at least partially disposed in the inter-strut space (56).

2. The compressor module (47, 49) according to claim 1, characterized in that Said fixed upstream portion (58) has a cavity (58.1) which opens towards a downstream side and which has the shape of a portion of a cylinder, said downstream flap (60) being received in said cavity (58.1).

3. The compressor module (47, 49) of claim 1, characterized by The annular row of variable stator vanes (37) is a first row of variable stator vanes, and the module (47, 49) further comprises an annular second row of variable stator vanes (39) arranged in the inter-strut space (56) and axially distanced from the first row of variable stator vanes.

4. The compressor module (47, 49) of claim 1, characterized by Said central hub (53) has a symmetry axis (4), the fixed upstream portion (58) of each strut (46, 48) of the annular row of struts (46, 48) being symmetrical about an axis (C) parallel to the symmetry axis of the central hub (53).

5. The compressor module (47, 49) of claim 3, characterized by Said second row of variable stator vanes (39) and said downstream flap (60) have respective trailing edges (39.2, 46.2) which share a common axial position.

6. The compressor module (47, 49) of claim 1, characterized by Said central hub (53) comprises a radially outer flow guiding surface (53.1) which, at said downstream flap (60), is oriented at an angle (a) of between 0° and 10° to the symmetry axis (4) of the central hub (53).

7. The compressor module (47, 49) according to claim 3, characterized in that Said downstream flap (60) has a respective cross-section which is substantially identical to the cross-section of said second row of variable stator vanes (39).

8. The compressor module (47, 49) of claim 3, characterized by A common actuation mechanism (51) controls the orientation of the second row of variable stator vanes (39) and the pivoting movement of the downstream flap (60).

9. A turbomachine (2) comprising a compressor (24) provided with a compressor module (47, 49) according to any one of claims 1 to 8, the turbomachine further comprising a row of rotor blades (40, 52) directly downstream of the module (47, 49).

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