Turbomachine blade lick, turbomachine and manufacturing process

Abstract

A turbomachine blade (30) intended to be mounted for rotation about a main axis (A) of the turbomachine, the blade having at a radial end a flange (34) comprising: a platform (34b); an upstream sealing flap (34a) and a downstream sealing flap (34a) extending radially outwards from the platform (34b); wherein a radial end of at least one of the upstream sealing flap (34a) and the downstream sealing flap (34a) is oblique with respect to a plane normal to the main axis (A) and passing through said radial end. Figure for the abbreviation: Fig. 2.

Description

Title of the invention: Turbomachine blade wiper, turbomachine and manufacturing method Technical field

[0001] The present disclosure relates to a turbomachine blade, and more particularly to a blade comprising a sealing lip. The present disclosure also relates to a moving wheel comprising the blade, a turbomachine comprising the moving wheel, a method for manufacturing the blade and a foundry mold capable of carrying out the method. Prior art

[0002] Current turbomachine turbines comprise rotating blades inside a stator. In order to minimize the flow of fluid bypassing the blades, i.e. the flow of fluid not exchanging mechanical power with the blades and thus reducing the efficiency of the turbomachine, abradable elements are provided radially opposite the blades so as to minimize clearances without damaging the blades.

[0003] In particular, sealing strips are provided on the blades to reduce these clearances after abrasion of the abradable elements.

[0004] Sealing lip structures are for example described in French patent applications FR3118990 A1 and FR 2967714 A1

[0005] The contact between the sealing lip and an abradable element during the first operating cycles of the turbomachine typically makes it possible to consume the abradable element by cutting so as to minimize the clearances without damaging the blades.

[0006] This contact can however cause unexpected parasitic movements during the first operating cycles of the turbomachine, leading to unforeseen contacts with the stator and thus to undesirable damage to the blade and the stator.

[0007] Furthermore, conventional sealing strips require relatively complicated manufacturing processes to implement.

[0008] There is therefore a need to provide a wiper structure at least partially free from the aforementioned drawbacks. Statement of the invention

[0009] To this end, the present invention relates to a turbomachine blade intended to be mounted in rotation around a main axis of the turbomachine, the blade having at a radial end a heel comprising: a platform; an upstream sealing lip and a downstream sealing lip extending ra- dially outwardly from the platform; wherein a radial end of at least one of the upstream sealing lip and the downstream sealing lip is oblique to a plane normal to the main axis and passing through said radial end. In addition or as a replacement, a radial end of at least one of the upstream sealing lip and the downstream sealing lip is oblique to a circumferential direction around the main axis.

[0010] The upstream and downstream directions are defined relative to the overall direction of circulation of the fluid in the turbomachine when the blade is mounted in the turbomachine.

[0011] By "fluid" is meant the fluid with which the blades are intended to react, typically air or exhaust gases at various temperature and pressure levels depending on the stage in which the blades are intended.

[0012] Typically, the overall direction of circulation of the fluid in the turbomachine is parallel to the main axis of the turbomachine.

[0013] Typically, the main axis of the turbomachine is coincident with the axis of rotation of the turbomachine blade.

[0014] In the present disclosure, the main axis of the turbomachine is the axis of rotation of the blade when the blade is mounted in the turbomachine. The axial direction corresponds to the direction of the axis of rotation of the blade and a radial direction is a direction perpendicular to the axis of rotation of the blade and intersecting this axis. Similarly, an axial plane is a plane containing the axis of rotation of the blade and a radial plane is a plane perpendicular to this axis. A circumference is understood to be a circle belonging to a radial plane and whose center belongs to the axis of rotation of the blade. A tangential or circumferential direction is a direction tangent to a circumference; it is perpendicular to the axis of rotation of the blade but does not pass through this axis. A tangential or circumferential plane is a plane strictly parallel to the axis of rotation of the blade, that is to say not intersecting this axis and not including this axis.An axial or radial section corresponds respectively to a section along an axial plane or along a radial plane. Hereinafter, a substantially radial plane or a substantially circumferential plane will be referred to respectively as a plane slightly inclined relative to a radial plane or a circumferential plane. The terms "internal" and "external" and their derivatives are defined relative to the main axis.

[0015] The obliqueness of the upstream and downstream sealing lips results in the formation of a leading edge of lips that can come into contact with an opposing abradable part of a turbomachine stator. The oblique structure in particular makes it possible to prevent excessive heating linked to the cutting of an abradable element of the stator, and to reduce the occurrence of parasitic movements leading to unwanted and uncontrolled damage to the lips and / or the stator.

[0016] Finally, such a structure is simpler to manufacture, being in particular compatible with a manufacturing process comprising casting and machining steps.

[0017] Typically, the radial end of the at least one of the upstream sealing lip and the downstream sealing lip is traversed right through from a first circumferential end surface to a second circumferential end surface by said plane normal to the main axis and passing through said radial end, the first circumferential end surface and the second circumferential end surface being circumferentially opposite surfaces of the at least one lip.

[0018] Such a structure makes it possible to ensure an overlap of successive blade wipers arranged circumferentially, and thus to prevent the formation of a possible leakage current between the wipers.

[0019] Typically, the radial end of the at least one sealing lip extends in a direction which forms a non-zero angle of less than 10° with the plane normal to the main axis and passing through said radial end, in particular seen in cross-section.

[0020] Typically, viewed in cross-section, the radial end of the at least one sealing lip forms a non-zero angle of less than 10° with the circumferential direction.

[0021] By cross-section of the blade, we mean a section along a plane perpendicular to a radial direction, that is to say along a circumferential plane.

[0022] Typically, the at least one of the upstream sealing lip and the downstream sealing lip has a thin plate shape.

[0023] By thin plate is meant a solid delimited by two parallel planes and of small thickness between the two planes compared to the dimensions of the two planes.

[0024] Typically, the upstream sealing lip and the downstream sealing lip are substantially parallel.

[0025] The at least one of the upstream sealing lip and the downstream sealing lip has a thin plate shape.

[0026] The present invention also relates to a turbomachine mobile wheel comprising a plurality of blades according to the present invention.

[0027] Typically, the impeller comprises a first vane according to the present invention comprising a first lip and a second vane according to the present invention comprising a second lip, the first vane and the second vane being circumferentially adjacent.

[0028] Typically, at least a portion of a circumferential end surface of the first wiper is mounted circumferentially opposite a portion of a circumferential end surface of the second lip.

[0029] Typically, the impeller comprises a disc, and the blades each comprise a root at the end of the blade opposite the heel, each root being mounted in a corresponding cell of the disc.

[0030] Typically, the impeller is a low pressure turbine impeller.

[0031] The present invention also relates to a turbomachine comprising the moving wheel according to the present invention.

[0032] The present invention also relates to a method of manufacturing a turbomachine blade intended to be mounted in rotation around a main axis of the turbomachine and having a heel at a radial end, in which: an upstream sealing lip and a downstream sealing lip extending radially outward from a platform of the blade heel are formed; and at least one of the upstream sealing lip and the downstream sealing lip is given an oblique shape relative to a plane normal to the main axis and passing through said radial end.

[0033] Typically, in the method: the upstream sealing lip, the downstream sealing lip and a casting channel connecting the upstream sealing lip and the downstream sealing lip are formed by casting a liquid material; and the casting channel is removed by machining.

[0034] Typically, the pouring channel extends between the upstream sealing lip and the downstream sealing lip.

[0035] Typically, the pouring of the liquid material is carried out from the pouring channel.

[0036] Typically, the upstream sealing lip and the downstream sealing lip are formed by casting a liquid material into a mold comprising a first cavity and a second cavity so as to form the upstream sealing lip and the downstream sealing lip respectively, and a third cavity intended to form the casting channel.

[0037] Typically, the liquid material comprises a metal, for example a nickel-based metal alloy, for example a nickel-based super alloy.

[0038] Typically, the upstream sealing lip and the downstream sealing lip comprise a metal, for example a nickel-based metal alloy, for example a nickel-based super alloy.

[0039] The present invention also relates to a foundry mold capable of carrying out the manufacturing method of the present invention, comprising: a first cavity and a second cavity respectively intended to receive a casting to form the upstream sealing lip and the downstream sealing lip, a casting channel fluidly connecting the first cavity and the second cavity. Brief description of the drawings

[0040] The object of the present disclosure and its advantages will be better understood upon reading the detailed description given below of various exemplary embodiments given as non-limiting examples. In order to facilitate the readability of the figures, numerical references of similar or identical elements have not been systematically reproduced at each occurrence of these elements. This description refers to the appended pages of figures, on which:

[0041] [Fig-1] [Fig.l] represents a simplified and partial schematic view of a turbo aircraft fan engine in axial section;

[0042] [Fig.2] [Fig.2] represents a schematic sectional view of a turbojet blade according to one embodiment of the invention.

[0043] [Fig.3] [Fig.3] represents a schematic sectional view along section plane III of [Fig.2].

[0044] [Fig.4] [Fig.4] represents a schematic sectional view along section plane IV of [Fig.2],

[0045] [Fig.5] [Fig.5] represents a schematic sectional view along section plane IV of [Fig.2] of a blade during manufacture.

[0046] [Fig.6] [Fig.6] represents a schematic view corresponding to the enlargement of [Fig.2] of the blade during manufacture. Description of the embodiments

[0047] [Fig. 1] shows an example of a mixed-flow turbojet engine 10 having a main axis A shown in dashed lines. The air flow in the turbojet engine 10 is shown in the diagram from left to right. The inlet of the turbojet engine 10 has a fan 11 driving the air inside the turbojet engine 10. The air flow is then divided into a primary air flow and a secondary air flow. The primary air flow is compressed successively by a low-pressure compressor 12 and a high-pressure compressor 13, driven respectively by a low-pressure turbine 16 and a high-pressure turbine 15. Between the compressors 12, 13 and the turbines 15, 16 is a combustion chamber 14 receiving the air compressed by the compressors 12, 13 and into which the fuel is injected in order to carry out combustion.The combustion gases exit the combustion chamber 14, driving the turbines 15 and 16, and join the secondary air flow at the outlet, the latter passing through the turbojet engine 10 on the radial periphery of the primary air flow. The combustion gases exiting the turbines 15, 16 are then ejected from the turbojet engine 10 through the nozzle 17, at the distal end of the turbojet engine 10.

[0048] Blade 30 and blade seal 34a structures will be described below with reference to the view of [Fig. 2] and the sectional views of FIGS. 3 and 4.

[0049] The blade 30 will be described in an orthogonal reference frame formed of a first direction X, a second direction Y and a third direction Z, where the first direction X is a direction of rotation of the blade and where the second direction Y is a circumferential direction.

[0050] In particular, the blade mounted in the low-pressure turbine 16 will be described, i.e. in which the first direction X is parallel to the main axis A, in which the second direction Y is a circumferential direction of the turbine 16, and in which the third direction Z is a radial direction of the blade.

[0051] Typically, the first direction X is oriented from upstream to downstream, so that in Figures 1 and 2, the upstream to downstream direction corresponds to a direction from left to right.

[0052] Typically, [Fig.2] is a schematic view of a blade 30 in section along an axial plane.

[0053] The blade 30 comprises a radially inner blade root 36 by which the blade 30 can be mounted on an inner casing (not shown), as well as a radially outer heel 34 provided to face a casing 20, typically an abradable element 22 of the casing 20.

[0054] The blade 30 also comprises a vane 32, extending between the blade root 36 and the heel 34 and capable of exchanging mechanical power with the fluid.

[0055] The blade 30 typically comprises sealing lips 34a, hereinafter simply referred to as "lips 34a", for example an upstream lip 34a and a downstream lip 34a, the downstream lip 34a being positioned downstream of the upstream lip 34a relative to the direction of circulation of the fluid.

[0056] Typically, the wipers 34a are part of the heel 34 of the blade 30, and extend from a platform 34b of the heel 34.

[0057] The wipers 34a are provided opposite the casing 20, in particular the abradable element 22 of the casing 20, so as to reduce the fluid leakage flow rate bypassing the blade 30 associated with a reduction in the mechanical power extracted from the fluid.

[0058] Typically, the height of the wipers 34a in the radial direction is provided so that during the first operating cycles of the turbomachine, the wipers 34a come into contact with the abradable element 22 of the casing 20 to degrade it by abrasion so that in nominal operation a small clearance is obtained, associated with a low leakage flow rate.

[0059] The wipers 34a are in particular provided to have the characteristics as described in relation to the enlargement of [Fig.2] as well as in the sectional views of Figures 3 and 4.

[0060] The wipers 34a extend in a substantially radial direction, that is to say a direction having a non-zero component in the third direction Z. In other words, the wipers 34a are provided at a radial end of the blade 30, and the wipers 34a themselves have a radial end.

[0061] For example, the platform 34b may extend in a plane comprising a circumferential direction (second direction Y) and slightly oblique with respect to this circumferential direction, so as to conform to the shape of the casing.

[0062] The wipers 34a can then be provided so as to extend substantially perpendicular to the plane of the platform 34b.

[0063] In the views of Figures 3 and 4, wipers 34a of three circumferentially successive blades 30 have been shown, where, for the sake of simplicity of the present description, the curvature effects along the circumference have not been shown. In other words, the sectional views of Figures 3 and 4 have been produced along the second curved circumferential direction Y.

[0064] [Fig. 3] thus represents three wipers 34a of three circumferentially successive blades 30, that is to say aligned in the second direction Y. In this figure, the blades 30 extend radially from the bottom to the top (third direction Z) and the fluid flows in a direction normal to the plane of the figure.

[0065] It will be noted that due to the obliqueness of the platform 34b, the third direction Z is not contained in the plane of [Fig.3], but its projection in the plane of the figure is indicated to simplify the understanding of the figure.

[0066] The wipers 34a may have a beveled end, typically a beveled radial end.

[0067] For example, the wipers 34a may have a beveled end forming a non-zero angle 0, where the angle 0 is the angle formed between a transverse direction of the wiper 34a, shown in dotted lines in [Fig. 3], and a direction of the beveled surface, seen in a plane comprising a height direction of the wiper 34a and a circumferential direction.

[0068] In other words, the lick 34a has a beveled end whose apex has an angle of measurement equal to 90°-0.

[0069] This beveled shape of the radial end causes a height differential on either side of the lip along the second circumferential Y direction.

[0070] The beveled shape is intended to constitute a leading edge of the wiper 34a on the abradable element 22. In other words, the wiper 34a is radially higher in the direction (i.e. the oriented direction) in which the blade moves in rotation.

[0071] For example, in the example of [Fig.3], the blades 30 are designed to move in rotation to the left.

[0072] Such a beveled shape makes it possible to improve the radial cutting of the abradable element 22 of the casing 20.

[0073] Although the wipers 34a of only three blades 30 have been shown, understands that all the licks 34a can have the same structure, so as to form a sawtooth structure.

[0074] [Fig.4] thus represents three pairs of wipers 34a upstream and downstream of three circumferentially successive blades 30, that is to say aligned in the second direction Y. The representation in the second direction Y is common to that of [Fig.3], so that in [Fig.4] the blades 30 are also provided to move in rotation to the left.

[0075] On the other hand, in the representation of [Fig.4], the direction of circulation of the fluid is in a direction from bottom to top.

[0076] A radial end of the wipers 34a, of which [Fig.4] represents a cross-section, may be provided to be oblique with respect to a circumferential direction.

[0077] Such an oblique structure makes it possible to improve the axial cutting of the abradable element 22 of the casing 20.

[0078] In other words, a radial end of the wipers 34a can form an angle α with a circumferential direction (second direction Y), where the angle α has a non-zero measurement less than 10°, for example between 3° and 7°.

[0079] The angle a is typically measured between the second direction Y and a middle fiber of the licks 34a shown in dotted lines in [Fig.4].

[0080] The angle a measured locally along the middle fiber can be variable along the middle fiber, therefore variable according to the circumferential direction; so that the lick 34a can be curved according to the circumferential direction.

[0081] The radial end of the wipers 34a comprises a first circumferential end surface 34a1 and a second circumferential end surface 34a2, the first circumferential end surface 34al and the second circumferential end surface 34a2 being circumferentially opposite.

[0082] As shown in the lips 34a of Figures 2 and 4, the obliqueness of the radial end of a lip 34a may be provided such that a plane P normal to the main axis A (i.e., a radial plane) and passing through the radial end of said lip 34a passes through the radial end of said lip 34a right through between the first circumferential end surface 34al and the second circumferential end surface 34a2. The plane P intersects the plane of [Fig.4] along a circumference C.

[0083] The obliqueness of the radial end of a wiper 34a may be provided so that a circumference C passes through the radial end of said wiper 34a right through between the first circumferential end surface 34a 1 and the second circumferential end surface 34a2.

[0084] For the purposes of representation and without loss of generality, the plane P and the circumference C are not necessarily represented on the same upstream or downstream lip 34a.

[0085] It is understood in fact that the obliquity of the radial end of a wiper 34a can be the obliquity of the radial end of an upstream wiper 34a, a downstream wiper 34a, or even both.

[0086] A circumferential arrangement of the wipers 34a then allows an overlap between the first circumferential end surfaces 34a1 and the second circumferential surfaces 34a2 of circumferentially adjacent wipers 34a, and thus maintains a clearance between the adjacent wipers 34a sufficiently small to prevent the occurrence of significant leakage current between the wipers 34a.

[0087] In other words, a first and a second circumferentially adjacent blades 30 may be provided such that a circumferential end surface 34al, 34a2 of a lip 34a of the first blade and a circumferential end surface 34al, 34a2 of a lip 34a of the second blade are at least partially opposite each other, i.e. at least a portion of a circumferential end surface 34al, 34a2 of the lip of the first blade is mounted circumferentially opposite a portion of a circumferential end surface 34al, 34a2 of the lip of the second blade.

[0088] In particular, the wipers 34a of the two blades may be two wipers 34a of the same nature, that is to say two upstream wipers 34a or two downstream wipers 34a.

[0089] In particular, as shown in the enlargement of [Fig.4], representing an enlargement at a gap between two adjacent wipers 34a, the first circumferential end surface 34al and the second circumferential end surface 34a2 respectively of two wipers 34a of adjacent blades 30 may be arranged so as to obtain an overlap width r, where the overlap width r is the width along which the first circumferential end surface 34al and the second circumferential end surface 34a2 of the adjacent blades are opposite each other, measured along the second direction Y.

[0090] Such dimensions make it possible to ensure sufficient sealing and thus to reduce the occurrence of a leakage current through the wipers 34a.

[0091] The spacing between the radial ends of the upstream and downstream wipers 34a may be constant along the first direction X, typically the spacing between the upstream and downstream wipers 34a. For example, the upstream and downstream wipers 34a may be substantially parallel.

[0092] In particular, the radial ends of the upstream and downstream wipers 34a may be substantially parallel.

[0093] In other words, the radial ends of the upstream and downstream wipers 34a of the same blade 30 can each form an angle with a circumferential direction whose measurements are included among the values ​​of the angle a described above. Typically, the angles formed by the radial ends of the upstream and downstream wipers 34a of a same dawn 30 with circumferential direction can be equal.

[0094] Instead of being parallel, the lips 34a may be provided with opposite obliquenesses. For example, the spacing between two upstream and downstream lips 34a may increase or decrease along the second direction Y.

[0095] It can be provided that only one of the upstream and downstream wipers 34a of the same blade 30 has a radial end forming an angle with a circumferential measurement direction included among the values ​​of the angle α described above. The other of the upstream and downstream wipers 34a of the same blade 30 can then have a radial end forming an angle with a circumferential measurement direction less than the values ​​of the angle α described above, or even zero.

[0096] The wipers 34a have a thickness e of between 0.5 mm and 5 mm, typically between 1 mm and 3 mm.

[0097] Typically, the thickness e is measured in a cross-section of the lip 34a, that is to say in a plane transverse to the height direction of the lip 34a which is substantially radial.

[0098] The wipers 34a may have a thin plate shape. In other words, the thickness e is substantially smaller than the length L of the wipers 34a, for example by a factor greater than 5.

[0099] In order to ensure the covering of the wipers 34a, the thickness e can be provided to be all the greater as the angle a is high.

[0100] The wipers 34a may be provided in a metallic material, for example a nickel-based metallic alloy, for example a nickel-based super alloy.

[0101] The wipers 34a can be produced by casting the wipers 34a upstream and downstream of the same blade 30 as well as a casting channel 34c connecting them.

[0102] For example, the casting channel 34c extends between the upstream and downstream lips 34a, from one lip 34a to the other, as shown in the schematic view of FIGS. 5 and 6 representing schematic views of a blade 30 during manufacture.

[0103] The entire heel 34, or even the entire blade 30, can be formed by a single casting.

[0104] The casting channel 34c may extend to the radial end of the lips 34a, as shown in [Fig.6].

[0105] The casting channel 34c can then be removed by machining.

[0106] The casting channel 34c is all the simpler to remove by machining as the spacing between the licks 34a is constant which allows the removal of the casting channel 34c by one or two passes of a passage tool suitably chosen according to the spacing.

[0107] Casting can be carried out from the casting channel 34c. This makes it possible in particular to reduce the formation of defects compared to casting from the lips 34a, and these defects can then be removed by machining.

[0108] Such a manufacturing method has the advantage of only involving manufacturing steps that are simple to implement.

[0109] Furthermore, the shape of the wipers 43a described above, in particular parallel wipers and / or having a thin plate shape, is highly compatible with such a simplified manufacturing method.

[0110] Although the present invention has been described with reference to specific embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0111] Typically, the characteristics of the wipers 34a described above may apply to the upstream and downstream wipers 34a of all the blades 30 of a turbomachine moving wheel, or may apply only to one of the upstream and downstream wipers 34a.

Claims

Claims

1. A turbomachine blade (30) intended to be mounted in rotation about a main axis (A) of the turbomachine, the blade having at a radial end a heel (34) comprising: a platform (34b); an upstream sealing lip (34a) and a downstream sealing lip (34a) extending radially outward from the platform (34b); wherein a radial end of at least one of the upstream sealing lip (34a) and the downstream sealing lip (34a) is oblique relative to a plane normal to the main axis (A) and passing through said radial end.

2. Blade (30) according to claim 1 wherein the radial end of the at least one of the upstream sealing lip (34a) and the downstream sealing lip (34a) is traversed right through from a first circumferential end surface (34al) to a second circumferential end surface (34a2) by said plane normal to the main axis (A) and passing through said radial end, the first circumferential end surface (34a 1) and the second circumferential end surface (34a2) being circumferentially opposite surfaces of the at least one lip (34a).

3. Blade (30) according to claim 1 or 2 in which the radial end of the at least one sealing lip (34a) extends in a direction which forms a non-zero angle of less than 10° with the plane normal to the main axis (A) and passing through said radial end.

4. A blade (30) according to any one of claims 1 to 3, wherein the at least one of the upstream sealing lip (34a) and the downstream sealing lip (34a) has a thin plate shape.

5. A blade (30) according to any one of claims 1 to 4, wherein the upstream sealing lip (34a) and the downstream sealing lip (34a) are substantially parallel.

6. A turbomachine wheel comprising a plurality of blades (30) according to any one of the preceding claims, wherein a first blade (30) comprises a first lip (34a) and a second blade (30) comprises a second lip (34a), the first and second blades (30) being circumferentially adjacent, and wherein at least a portion of a circumferential end surface- (34al, 34a2) of the first wiper (34a) is mounted circumferentially opposite a portion of a circumferential end surface (34al, 34a2) of the second wiper (34a).

7. Turbomachine (10) comprising a moving wheel according to claim A

8. O. Method for manufacturing a turbomachine blade (30) intended to be mounted in rotation about a main axis (A) of the turbomachine and having at a radial end a heel (34), in which: an upstream sealing lip (34a) and a downstream sealing lip (34a) are formed extending radially outwards from a platform (34b) of the heel (34) of the blade (30); and at least one of the upstream sealing lip (34a) and the downstream sealing lip (34a) is given an oblique shape relative to a plane normal to the main axis (A) and passing through said radial end.

9. The method of claim 8, wherein: the upstream sealing lip (34a), the downstream sealing lip (34a) and a casting channel (34c) connecting the upstream sealing lip (34a) and the downstream sealing lip (34a) are formed by casting a liquid material; and the casting channel (34c) is removed by machining.

10. A method according to claim 9, wherein the pouring of the liquid material is carried out from the pouring channel (34c).

11. Foundry mold capable of carrying out the manufacturing method according to claim 8 or 9, comprising: a first cavity and a second cavity respectively intended to receive a casting to form the upstream sealing lip (34a) and the downstream sealing lip (34a), a casting channel (34c) fluidly connecting the first cavity and the second cavity.

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