INTER-BLADE PLATFORM FOR AN AIRCRAFT TURBOMACHINE PROPELLER

Abstract

The invention relates to an inter-blade platform (102) for a propeller (100) of an aircraft turbomachine, this platform, of generally elongated shape, comprises: a wall (200) and at least one fixing element (204, 206) of this wall; two longitudinal edges (2081, 2082) on which sealing joints (300) are respectively fixed, each of the joints having a generally elongated shape and extending along the corresponding edge; each of the joints comprises a longitudinal base (300a) fixed on a first longitudinal surface (208a, 208d) of the edge and an elastically deformable longitudinal lip (300b) connected to the base (300a), the base further comprising at least one longitudinal rim (300c, 300d) which is fixed on a second longitudinal surface (208b) of the edge and / or on a third longitudinal surface (208c) of said edge, the second surface (208b) and / or the third surface (208c) not being aligned with the first surface (208a, 208d).Figure for abstract: Figure 4A.

Description

Title of the invention: INTER-BLADE PLATFORM FOR AN AIRCRAFT TURBOMACHINE PROPELLER Technical field of the invention

[0001] The present invention relates to an inter-blade platform for an aircraft turbomachine propeller and a propeller comprising such a platform. Technological background

[0002] A turbojet engine, for example, and in a non-limiting manner, with a double flow comprises a gas turbine engine traversed by a gas flow designated the primary flow driving a propeller or a fan delivering an air flow, designated the secondary flow. When the propeller is arranged at the front of the engine, it discharges the sucked air which is separated into two concentric flows: one the primary flow and the other the secondary flow. The air of the primary flow is compressed again then mixed with a fuel in a combustion chamber to produce a high-energy gas flow which sets in motion the turbines arranged downstream. One of the turbines is connected by a shaft to the rotor of the propeller which it drives. The secondary flow in civil engines provides the majority of the engine's thrust and the diameter of the propeller is consequently very large.

[0003] The propeller rotor comprises a wheel whose hub is secured to the drive shaft and the rim comprises cells oriented substantially axially. The axial direction is that of the drive shaft. The blades are engaged by their root in the individual cells, and form the fan rotor. A propeller blade comprises a root, an aerodynamic profile blade and a stilt between the root and the blade. To constitute the boundary surface between the rotor rim and the air stream and to ensure the continuity of the primary stream, intermediate platforms are arranged between the blades. Different from the upper compression stages and due to the large dimensions of the blades, the platforms of the propeller rotor are not an integral part of the blades but are separate parts. It should be noted that the internal radius of the air stream increases significantly between the inlet and the outlet of the propeller rotor.

[0004] Each platform must ensure an aerodynamic function which is its main function and a definition of the air flow vein.

[0005] In addition, each platform must satisfy all operating conditions, namely ensuring performance for the entire operating envelope, for example a flight for an aircraft, ensuring safety requirements and ensuring the availability of the rotor as part of the engine for commercial use.

[0006] With regard to safety, each platform must be capable of absorbing a significant amount of energy by crushing its lateral edges which run respectively along a lower surface of a blade and an upper surface of an adjacent blade.

[0007] A clearance is provided between the platforms and the blades to allow the latter limited movement during the various phases of engine operation. This clearance is filled by a seal made of elastomeric material fixed along the lateral edges of the platform and bearing against the adjacent blade.

[0008] The seal is for example, according to the prior art, of elongated shape with a constant profile from one end to the other. Transversely, it can be composed of three parts: a part for attachment to the platform, a flexible part and a swollen part shaped so as to ensure contact with the surface of the adjacent part. The flexible part allows the seal to be adapted to the distance separating the edge of the platform from the surface of the facing blade.

[0009] It is noted that after a certain duration of operation of the turbomachine on which they are mounted, they present areas of wear and rupture. This results in a loss of sealing at the fan blade root. Poor sealing has an impact on the flow and efficiency of the compressor stages directly downstream of the propeller or fan. It also has an impact on the pumping margin.

[0010] The seals are therefore wearing parts which should be replaced regularly during the life of the turbomachine to ensure optimal operation of the latter.

[0011] It may thus be desirable to provide a platform which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0012] There is therefore proposed an inter-blade platform for an aircraft turbomachine propeller, this platform comprising a wall and at least one element for fixing this wall, the platform having a generally elongated shape and comprising two longitudinal edges which respectively have shapes complementary to a lower surface of a blade and to an upper surface of an adjacent blade, the platform comprising a first aerodynamic face and a second face opposite the first face and on which said at least one fixing element is connected, sealing joints being fixed respectively on the two longitudinal edges of the platform, each of the joints having a generally elongated shape and extending along the corresponding edge, characterized in that each of the joints comprises a longitudinal base fixed on a first longitudinal surface of the edge and an elastically deformable longitudinal lip connected to the base,the base further comprising at least one longitudinal rim which is fixed on a second longitudinal surface of the edge and / or on a, third longitudinal surface of said second face, the second surface and / or the third surface not being aligned with the first surface.

[0013] Advantageously, there is an increase in the contact surfaces between the edge of the platform and the seal. This increase in contact surfaces, and therefore in the bonding of the seal to the edge of the platform, has the effect of improving the attachment of the seal to the platform.

[0014] Thus, thanks to the invention, it is possible to prevent detachment or wear (by erosion or contact with the platform) of the seal.

[0015] This reduction in the risk of detachment or wear also makes it possible to improve the sealing in the area of ​​the edge of the platform (reducing the risk of loss of sealing in the area).

[0016] The invention may further comprise one or more of the following optional features, in any technically possible combination: - the second surface is parallel to the first surface; - the third surface is perpendicular to the first surface; - the lip and the base have a general V-shape in cross-section; - said at least one rim is formed by an extension of one end of the lip connected to the base; - said base comprises an end connected to the lip and an opposite free end at which said at least one rim is located; - the first surface is located in a longitudinal recess of the corresponding edge, and said second surface and / or said third surface are located outside this recess; - the joints are fixed by gluing to the wall; - the seals are made of elastomer.

[0017] The invention also relates to a propeller for an aircraft turbomachine, comprising a hub carrying blades as well as platforms identical to that described above, each of the platforms being fixed by said at least one element on the hub and being interposed between two adjacent blades, the lips of the sealing joints bearing respectively on the intrados of one of these blades and on the extrados of the other of these blades. Brief description of the figures

[0018] 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.lA] is an exploded view of a part of a propeller for an aircraft turbomachine to which the invention can be applied; - [Fig.lB] is a partial perspective view of the propeller of fig. 1 assembled; - [Fig.2A] is a schematic perspective view of a composite platform, seen from above or from the outside and which does not form part of the invention, - [Fig.2B] is a schematic sectional view along line IV-IV of [Fig.2A], - [Fig.2C] is a schematic sectional view along line VI-VI of [Fig.2A]; - [Fig.3A] is a perspective view of a platform with joints according to the prior art; - [Fig.3B] is a schematic sectional view of the edge of a platform with a joint according to the prior art; - [Fig.3C] is a schematic view in partial section of a blade inserted between two platforms with seals at their edge according to the prior art; - [Fig.4A] is a sectional view of the edge of the platform according to the invention; - [Fig.4B] is a sectional view of a first variant of the edge of the platform according to the invention; and - [Fig.4C] is a sectional view of a second variant of the edge of the platform according to the invention. Detailed description of the invention

[0019] [Fig.1A] represents an exploded view of a propeller or a fan for an aircraft turbomachine, to which the invention can be applied.

[0020] The propeller 106 comprises at least one hub or disc 106 having a longitudinal axis XX or motor axis, the hub carrying blades 104 as well as platforms 102.

[0021] The hub comprises at least one rim 106a which comprises cells Ei04, oriented substantially axially relative to the longitudinal axis XX.

[0022] The cells have longitudinal edges facing the axis XX. The blades are slid into the cells by an open end. In [Fig.lA], a single blade 104 is shown in position for its introduction into the cell Ei04. The blade 104 comprises a root 104a, a stilt 104b and a blade 104c. The root 104a is shaped so as to be housed in a cell E104, with lateral bulges by which it bears, in a radial direction towards the outside, against the longitudinal edges of the cell facing the axis XX. The root is held in support by shims 108 which are slid during assembly, under the root 104a, along the bottom of the cell Ei04. The device for holding the blades on the disc further comprises means of axial locking 110, 112, 114 of the blades 104 individually relative to the hub or disc 106.

[0023] The fan blades do not have an integrated platform, unlike the other compressor blades on the turbomachine. The function is provided by the inter-blade platforms 102, which are partly free to move relative to the blades 104.

[0024] The platforms 102 are arranged in a housing E102 located between two cells E104. The platforms 102 are therefore interposed between the blades 104 of the propeller or fan 100 and fixed to the periphery of the hub 106. Each platform 102 can therefore be interposed between two consecutive fan blades. They are arranged between two adjacent blades.

[0025] [Fig. 1B] illustrates for example a partial perspective view of an assembled propeller, with two blades 104i 2 and three platforms 102i 3. In this example, the platform 1022 is interposed between the blades 104i and 1042.

[0026] Figures 2A to 3C describe exemplary embodiments of platforms which are not part of the invention.

[0027] The inter-blade platform 102 of FIGS. 2A to 3C comprises a wall 200 of elongated shape and configured to extend between two fan blades.

[0028] With reference to [Fig.2A], this wall 200 comprises an aerodynamic external face 200a and an internal face 200b, as illustrated in [Fig.2B] (sectional view of the platform in plane IV-IV), the internal face 200b of the wall making it possible to delimit the primary air stream guided between two adjacent blades.

[0029] Each platform 102 comprises at least one fixing element 204, 206 to the hub 106 or disc of the propeller 100. Thus, there may be provided on the internal surface 200b of each platform 102, as illustrated in [Fig.2B], a fixing lug 206 configured to be fixed to the hub 106 or disc of the propeller 100 or fan by means of screws 204.

[0030] In another variant, not shown, the fixing means may be at least one screw 204.

[0031] In another variant, not shown, each platform may comprise several means of attachment to the hub such as, for example, and in a non-limiting manner, several attachment tabs 206 and / or several screws 204.

[0032] With reference to [Fig. 2C], which illustrates a cross-sectional view of platform 102 of [Fig. 2A] in the VLVI plane, the platform further comprises a hollow body 210 configured to reinforce the platform 102. The hollow body 210 comprises a first end on which the wall 200 of the platform 102 rests, side walls 210a, 210b which extend along the platform and a second end 210c opposite the first end, the second end being closed so that the side walls 210a, 210b of the body 210, the wall 200 of the platform and the second end 210c delimit a volume of the hollow body 210.

[0033] The platform 102 may also comprise stiffeners (not shown) fixed on its internal face 200b.

[0034] Still with reference to [Fig.2C], the wall 200 of the platform 102 comprises longitudinal edges 208i, 2082 configured to receive at least one seal 300 capable of ensuring sealing between the platform 102 and the blades 104 of the propeller or the fan 100.

[0035] Thus, the edges 208, 208i, 2082 of the wall 200 of the platform 102 may, for example, and in a non-limiting manner, comprise a groove or a housing provided along the lateral edges of the wall 200 forming the platform 102, in order to receive the sealing joints 300, 300i, 3002.

[0036] The sealing joints are fixed, for example by gluing, respectively on the two longitudinal edges of the platform, each of the joints having a generally elongated shape and extending along the corresponding edge as illustrated, for example, in [Fig.3A]. In this example, the platform comprises three fixing lugs 2061, 2062, 2063.

[0037] With reference to [Fig.3B], each of the seals comprises a longitudinal base 300a fixed on a first longitudinal surface 208a, 208d of the edge and an elastically deformable longitudinal lip 300b connected to a first end of the base 300a.

[0038] The lips 300b are configured to come into contact with the neighboring part, that is to say the blade 104 of the propeller 104 or of the fan as illustrated for example in [Fig.3C].

[0039] The technology of the composite platforms described above is not entirely satisfactory because it has drawbacks such as, for example, the turning over of the joints, their detachment, their tearing in fatigue, their wear by erosion or by contact (fretting).

[0040] All these drawbacks can lead to local losses of sealing. This can result, for example and in a non-limiting manner, in the accumulation of frost and thus the creation of an unbalance (mass not perfectly distributed on the rotor) leading to an imbalance and therefore a drop in performance of the propeller 100 or the fan.

[0041] With reference to Figures 4A to 4C, a platform according to the invention will now be described. Preferably, the platform is made of 3D woven composite material.

[0042] The inter-blade platform 102 comprises at least the elements mentioned above.

[0043] In particular, the platform 102 comprises a wall 200 and at least one element 204, 206 for fixing this wall to the hub 106 (or disc) of the rotor. The platform 102 has a generally elongated shape and comprises two longitudinal edges 208 b 2082 which respectively have shapes complementary to a lower surface of a blade 104 and to an upper surface of an adjacent blade 104.

[0044] The platform comprises a first aerodynamic face 202a and a second face 202b opposite the first face 202a and on which the fixing elements 204, 206 are connected.

[0045] The platform 102 comprises sealing gaskets 300 fixed respectively on the two longitudinal edges 208i, 2082 of the platform 102, each of the gaskets 300 having a generally elongated shape and extending along the corresponding edge.

[0046] With reference to Figures 4A-4C, each seal 300 comprises a longitudinal base 300a fixed on a first longitudinal surface 208a, 208d of the edge and an elastically deformable longitudinal lip 300b connected to the base.

[0047] The lips of the sealing gaskets are configured to bear on the intrados or on the extrados of the blades of a propeller 106 or fan.

[0048] The lip 300b and the base 300a have a general V-shape in cross-section.

[0049] The seals 300 are fixed by gluing. Preferably, the seals 300 are made of elastomer and preferably of ethylene propylene elastomer (EPDM).

[0050] With reference to [Fig.4A], illustrating a sectional view of the edge 208i, 2082 of a platform 102 according to the invention, the base 300a of the seal 300 of the platform 102 further comprises a longitudinal rim 300c which is fixed on a second longitudinal surface 208b of the edge 208. The longitudinal rim 300d is located at a free end of the base 300a, the free end of the base 300a being opposite the end of the base 300a which is connected to the lip 300b.

[0051] In this configuration, the second surface 208b is parallel (or perpendicular) to the first surface 208a (208d). The first surface 208a, 208d is located in a longitudinal recess of the corresponding edge 208b 2082 and the second surface 208b is located outside this recess.

[0052] Advantageously, there is an increase in the contact surfaces between the edge 208i, 2082 of the platform 102 and the seal 300, capable of ensuring sealing between the platform 102 and the blades 104 of the propeller 100.

[0053] Thus, advantageously, those skilled in the art will understand that by having a greater number of contact surfaces, and therefore of bonding of the seal 300, the risk of detachment or wear (by erosion or contact with the platform) of the seal is reduced. Reducing the risk of detachment or wear also improves the seal in the platform edge area (reducing the risk of loss of seal in the area).

[0054] In the examples of Figures 3B and 3C, for example, there are fewer contact surfaces between the seal 300 and the platform 102, which may increase the risk of detachment or wear of the seal unlike the platform 102 of the present invention.

[0055] In a second variant, illustrated in [Fig.4B], the base 300a comprises a longitudinal rim 300d which is fixed on a third longitudinal surface 208c of the edge 208. In this variant, the rim 300d is formed by an extension of the end of the lip 300b connected to the base 300a.

[0056] In this configuration, the third surface 208c is perpendicular (or parallel) to the first surface 208a (208d).

[0057] With reference to [Fig.4C], a third variant will now be described.

[0058] In this configuration, the base comprises a first longitudinal rim 300c which is fixed on the second longitudinal surface 208b of the edge 208 and a second rim 300d fixed on the third longitudinal surface 208c of the edge 208.

[0059] In this configuration, the first 300c and second 300d edges correspond respectively to the edges of [Fig.4A] and 4B.

Claims

Claims

1. Inter-blade platform (102) for a propeller (100) of an aircraft turbomachine, this platform (102) comprising a wall (200) and at least one fixing element (204, 206) of this wall (200), the platform (102) having a generally elongated shape and comprising two longitudinal edges (208 b 2082) which respectively have shapes complementary to a lower surface of a blade and to an upper surface of an adjacent blade (104), the platform (102) comprising a first aerodynamic face (202a) and a second face (202b) opposite the first face (202a) and on which said at least one fixing element (204, 206) is connected, seals (300) being fixed respectively on the two longitudinal edges (208 b 2082) of the platform (102), each of the seals (300) having a generally elongated shape and extending along the corresponding edge,characterized in that each of the joints (300) comprises a longitudinal base (300a) fixed on a first longitudinal surface (208a, 208d) of the edge and an elastically deformable longitudinal lip (300b) connected to the base (300a), the base (300a) further comprising at least one longitudinal rim (300c, 300d) which is fixed on a second longitudinal surface (208b) of the edge and / or on a third longitudinal surface (208c) of said edge, the second surface (208b) and / or the third surface (208c) not being aligned with the first surface (208a, 208d).,

2. The platform of claim 1, wherein the second surface is (208b) parallel to the first surface (208a).

3. A platform according to claim 1 or 2, wherein the third surface (208c) is perpendicular to the first surface (208a).

4. Platform according to one of the preceding claims, in which the lip (300b) and the base (300a) have a general V-shape in cross section.

5. Platform according to one of the preceding claims, in which said at least one rim (300d) is formed by an extension of one end of the lip (300b) connected to the base (300a).

6. Platform according to one of the preceding claims, in which said base (300a) comprises an end connected to the lip (300b) and an opposite free end at which said at least one rim (300c) is located.

7. Platform according to one of the preceding claims, wherein the first surface (208a) is located in a longitudinal recess of the corresponding edge (2081, 2082), and said second surface (208b) and / or said third surface (208c) are located outside this recess.

8. Platform according to one of the preceding claims, in which the joints (300) are fixed by gluing to the wall (200).

9. Platform according to one of the preceding claims, in which the seals are made of elastomer.

10. Propeller (100) for an aircraft turbomachine, comprising a hub (106) carrying blades (104) as well as platforms (102) according to one of the preceding claims, each of the platforms (102) being fixed by said at least one element (204, 206) on the hub (106) and being interposed between two adjacent blades (104), the lips (300b) of the sealing joints (300) bearing respectively on the intrados of one of these blades (104) and on the extrados of the other of these blades (104).

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