ROTOR DISC FOR AN AIRCRAFT TURBOMACHINE
The rotor disk design with inclined flanks addresses premature failure by reducing mechanical stresses, enhancing reliability and structural integrity under normal and failure conditions.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2021-10-01
- Publication Date
- 2026-06-05
AI Technical Summary
Existing rotor disk recesses in aircraft turbomachines experience premature failure due to thermomechanical stresses, particularly at the necks of the intermediate housing, leading to wear and potential loss of mechanical integrity under normal operation or failure conditions.
The rotor disk design features recesses with inclined flanks having a negative angle of inclination, reducing the clearance between the blade root and the disk, thereby minimizing mechanical stresses and enhancing the mechanical strength of the intermediate housing.
The optimized rotor disk design reduces mechanical stresses by approximately 80 MPa, improving reliability and maintaining structural integrity under severe operating conditions without significant cost or size penalties.
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Abstract
Description
Title of the invention: ROTOR DISC FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention
[0001] The present application relates to the general field of attachments for movable rotor disc blades of an aircraft turbomachine, and more particularly, an optimized profile of a cavity receiving the root of the rotor blade. Technical background
[0002] With reference to [Fig. 1], a rotor 10 of an aircraft turbomachine 100 conventionally comprises a disk or hub 1 having an axis of rotation (which is not visible in the figures). The disk 1 comprises a plurality of blades 2 on its outer periphery. Each blade 2 comprises a blade 20 having an aerodynamic profile. The blade 20 comprises a leading edge 22, a trailing edge 24, an intrados, and an extrados. Each blade 2 extends along an axis B of extension, and an axial end of the blade 20 is connected by a platform 3 to a foot 4.
[0003] The rotor disk includes at its periphery a series of recesses for receiving the blade roots. The blade roots are generally single-lobed (or dovetailed) or multi-lobed. The shape of the blade roots is complementary to that of the recesses provided at the outer periphery of the disk. The roots are fitted into the recesses so that the platforms are arranged circumferentially (with respect to the axis of the disk) next to each other and around the disk, and define by their upper surfaces (or radially external surfaces with respect to the axis of the disk) the inner periphery of an annular flow channel for an airflow in the turbomachine.
[0004] Fig. 2 schematically illustrates an example of a rotor disc 1 of the two-bearing type to be fixed to a two-lobe rotor blade foot 4 2. The disk 1 has cavities 5 on its outer periphery. The blade feet 4 are mounted in the cavities 5. Each of the cavities 5 includes an opening 52 through which the blade foot 4 is fitted, and a base 54 located radially opposite the opening 52. Each of the cavities 5 includes a main housing 6, called the lower housing, which is located radially towards the inside of an axis A of the disk 1, and an intermediate housing 7 which is located radially towards the outside of the axis A. The intermediate housing 7 can be divided into two sub-housings or half-cavities 70, 70' with respect to a median plane of symmetry PA passing through the axis A. The half-cavities 70, 70' are therefore located on either side of the plane PA.These half-cavities 70, 70' each comprise a second lateral support surface 72, 72', a flank 76, 76' and a neck 74, 74' connecting the second lateral surface. The main lobe 6 includes first lateral support surfaces 62, 62' extending radially outwards from axis A and thus oriented towards blade 2. The sides 76, 76' are inclined at an angle of inclination a0, a0', referred to as positive, with a plane T that is substantially perpendicular to axis A. The lateral support surfaces 62, 62', 72, 72' each have an angle of inclination, referred to as negative, with plane T.A "positive angle" with respect to a horizontal plane or axis is defined as an angle that rotates counterclockwise from the horizontal plane (i.e., from the horizontal T-plane towards the blade), while a "negative angle" with respect to the same horizontal plane is an angle that rotates clockwise from the horizontal plane (i.e., from the horizontal T-plane towards the blade root and then the blade). The first lateral bearing surfaces 62, 62' form a first span, and the second lateral bearing surfaces 72, 72' form a second span for each of the cells 5. The term "span" refers to the interface and contact areas between the root of the moving blade and the rotor disk.
[0005] During the rotation of the blades 2 in the rotor 10, the blades 2 are mobile relative to the disk 1. The blades 2 are subjected to radial outward stresses due to centrifugal forces. More specifically, the lateral bearing surfaces 62, 62', 72, 72' of the recesses 5 in the rotor disk come into contact with complementary bearing faces of the lobes of the rotor blade root. The blade roots thus cooperate by bearing against the recesses of the disk to maintain the attachment between the blade and the rotor disk.
[0006] Although the multi-lobe rotor disk recesses retain the movable rotor blade, they nevertheless present some problems. In particular, the rotor disk recesses in the prior art configuration can subject the part to thermomechanical stresses during normal operation (such as during an aircraft mission) or in the event of a failure (such as an overspeed start) of the turbine. For example, the contact and friction of the blade roots on the rotor disk can cause wear, or even premature failure, of the contacting parts. Indeed, during operation, the centrifugal force exerted by the blade on the disk generates stresses, primarily tensile (notably radial forces / loads at the blade's axis of rotation), on the necks of the intermediate lobe of the rotor disk recesses.For a two-span cavity (i.e., with two housings), the radial load is finely distributed over the two necks of the intermediate housing. In the event of failure of the neck of the intermediate housing (particularly through cracks initiating and propagating from this neck until the loss of the intermediate housing), the radial load is distributed evenly across the two necks of the intermediate housing. (medial), the radial load is then borne solely by the neck of the lower housing. This can lead to premature failure of the rotor disc.
[0007] Thus, there is a need to optimize the rotor disk provided with housing cells for the blade feet of an aircraft turbomachine, in particular by reducing the mechanical stresses to which the cells in contact with the blade feet are subjected during the operation of the rotor. Summary of the invention
[0008] The present invention aims to overcome one or more of the aforementioned drawbacks by proposing a solution that is simple, effective and economical.
[0009] The invention thus proposes a rotor disk for an aircraft turbomachine, the disk having an axis of elongation A and comprising on its outer periphery recesses each intended for the insertion of a rotor blade root, each of the recesses having a median plane of symmetry PA passing through said axis A and being of the type with at least two bearing surfaces, each of the recesses comprising: - a lower main housing comprising two initial lateral support surfaces located on either side of plane PA, oriented towards the outer periphery of the disc, and forming a first bearing surface of the cavity, - at least one intermediate housing comprising two second lateral support surfaces which are located on either side of the PA plane and which are oriented towards the outer periphery of the disc and form a second bearing surface of the cavity, each of these second surfaces being connected by a neck to a flank oriented towards the bottom of the cavity and located substantially opposite one of the first lateral support surfaces of the main housing.
[0010] According to the invention, said flanks are inclined with respect to a plane T7 perpendicular to said axis A so that the flanks move away from the outer periphery of the disk as they move away from the plane PA.
[0011] The flanks of at least one intermediate housing of the rotor disk cells according to the invention have a reversed configuration compared to that of conventional prior art flanks. Specifically, the flanks have a negative angle of inclination (i.e., an angle inclined clockwise or along a direction radially internal to axis A) with respect to a plane T7 perpendicular to axis A. This reduces the clearance between the flanks of the blade root and the rotor disk during operation to a maximum permissible clearance (which is, for example, on the order of 0.25 mm). In this way, the mechanical stresses applied to the flanks of the intermediate housing are reduced. Thus, the mechanical strength of the neck of the intermediate housing of the cells is significantly improved during normal operation of the turbomachine or in the event of a failure (for example, in the event of an overspeed start).
[0012] Furthermore, under severe operating conditions of the rotor disc of the invention (in particular with maximum rotation speed and temperature), the Applicant estimated a reduction in mechanical stresses of approximately 80 MPa due to the optimized profile of the present invention.
[0013] The invention therefore has the advantage of offering a simple design, providing very high reliability, and little penalizing in terms of cost and size of the blade in the turbomachine rotor.
[0014] The rotor disc according to the invention may comprise one or more of the following features, taken individually or in combination with each other:
[0015] - said flanks are inclined with respect to the plane at an angle a, a' between 1 and 20°, preferably between 2 and 10°, and for example around 5°;
[0016] - said sides are substantially flat;
[0017] - each of said flanks is connected to one of the first bearing surfaces of the lobe principal by a flat face which moves away from the outer periphery of the disk as it approaches the PA plane;
[0018] - each of said collars has a generally rounded convex shape or comprises a panel cut.
[0019] The present invention also relates to a turbomachine rotor, in particular for aircraft, comprising: - a rotor disc according to one of the features of the invention, - a plurality of rotor blades having a main axis B and comprising a blade connected at one of its longitudinal ends to a foot which is intended to be fitted into one of the recesses of the rotor disc.
[0020] The turbomachine rotor according to the invention may comprise one or more of the following features, taken individually or in combination with each other:
[0021] - each of said flanks of the foot and the disc are separated by a maximum clearance J' between 0.10 and 0.50 mm, preferably 0.25 mm;
[0022] — the rotor is a turbine, for example a high-pressure turbine and / or a turbine low pressure, from the turbomachine;
[0023] — the rotor is a rotor of a blower or a rotor of a turbine compressor bomachine.
[0024] The present invention also relates to a turbomachine, particularly for aircraft, comprising at least one blade according to one of the features of the invention or at least one rotor according to one of the features of the invention. The turbomachine may be a turbojet or a turboprop. Brief description of the figures
[0025] Other features, objectives and advantages of the present invention will become apparent from the following detailed description and from the accompanying drawings, which are given by way of non-limiting examples and on which:
[0026] - [Fig. 1] is a partial schematic cross-sectional view of a turbomachine rotor,
[0027] - [Fig. 2] is a schematic cross-sectional view of a cavity in a rotor disk according to prior art,
[0028] - [Fig. 3] is a schematic cross-sectional view of a cavity in a rotor disk of turbomachine according to the invention, and
[0029] - [Fig. 4] is a partial schematic cross-section of a rotor blade foot according to the invention,
[0030] - [Fig. 5] is a partial schematic cross-section of a turbomachine rotor according to the invention comprising the blade foot of the [Fig.4] fixed in a cavity of the rotor disc of the [Fig.3]. Detailed description of the invention
[0031] An aircraft turbomachine generally comprises, from upstream to downstream, a blower, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine.
[0032] By convention, in the present application, the terms "internal" and "external" are defined radially with respect to a longitudinal axis, in particular of the turbomachine, which is generally an axis of rotation of these rotors.
[0033] Figures 1 and 2, illustrating a rotor disc 1 for a rotor blade 2 according to the prior art, have been described above.
[0034] An embodiment of a disk 1 and a blade 2 of a rotor 10 for a turbomachine 100, in particular for aircraft, are schematically represented in at least one of the figures 3 to 5.
[0035] With reference to [Fig. 3], the rotor disc 1 (also referred to as the "attachment profile" or "cell profile" of the rotating rotor blade) according to the invention extends along an elongation axis A. The disc 1 therefore comprises a plurality of cells 5 on the outer periphery of the disc. Each of these cells 5 is intended to be fitted with a rotor blade foot 4. Each cell 5 comprises an opening 52 located at the outer periphery of the cell, and a bottom 54 located radially opposite the opening 52. Each of the cells 5 has a median plane of symmetry PA passing through the axis A.
[0036] The disc 1 according to the invention is of the type with at least two bearing surfaces. In the example, the disc 1 has two bearing surfaces allowing contact or abutment between the blade foot 4 and the disc 1 during operation.
[0037] Each of the recesses 5 of the disk 1 comprises a lower principal housing 6 located radially internally (with respect to axis A) and at least one intermediate housing 7 located radially externally (with respect to axis A). In the example shown in the figures, the intermediate housing 7 is open towards the outer periphery of the disk (in particular through the opening 52) and also on a side opposite the outer periphery of the disk to open into the principal housing 6. The principal housing 6 is, on the one hand, closed on one side opposite the outer periphery of the disk (in particular by the bottom 54), and on the other hand, open on the other side to open into the intermediate housing 7.
[0038] The main housing 6 comprises two first lateral bearing surfaces 62, 62' oriented towards the opening 52 or the outer periphery of the cavity 5. These first lateral bearing surfaces 62, 62' form a first bearing surface of the cavity 5. The first lateral bearing surfaces 62, 62' may be substantially flat. Each of the first lateral bearing surfaces 62, 62' is inclined at an angle (called a negative angle) with respect to a plane T6 substantially perpendicular to the axis A, such that these first lateral bearing surfaces 62, 62' move away from the opening 52 (or the outer periphery of the cavity 5) as they move away from the plane PA. Each of these first lateral bearing surfaces 62, 62' is connected to the intermediate housing 7 by a flat face 67, 67'.This flat face 67, 67' is inclined with respect to a plane T7 such that this flat face 67, 67' moves away from the opening 52 (or the external periphery of the alveolus 5) as it approaches the plane PA. The plane T7 is substantially parallel to the plane T6.
[0039] The intermediate housing 7 can be separated into two sub-housings or half-cavities 70, 70' with respect to the median plane of symmetry PA. The half-cavities 70, 70' are therefore located on either side of the plane PA. These half-cavities 70, 70' (and consequently the intermediate housing 7) each comprise a second lateral support surface 72, 72', a flank 76, 76' and a neck 74, 74' connecting the second lateral support surface 72, 72' to the flank 76, 76'.
[0040] The collars 74, 74' may have a generally rounded convex shape ([Fig. 3]) or a chamfered shape ([Fig. 5]). The collars 74, 74' may have a maximum height h between 5 and 15 cm, this height h being measured with respect to an axis perpendicular to axis A or plane T7. Preferably, the height h is on the order of 7 cm.
[0041] The second lateral support surfaces 72, 72' and the flanks 76, 76' can be substantially flat.
[0042] The second lateral support surfaces 72, 72' are oriented towards the opening 52 (or the outer periphery of the socket 5) and form a second bearing surface of the socket 5. The second lateral support surfaces 72, 72' are each inclined at an angle of inclination [3, [3'] with respect to a plane Tr such that these The second surfaces 72, 72' move away from the opening 52 (or the outer periphery of the alveolus 5) as they move away from the plane PA. The plane Tr is substantially parallel to the planes T6 and T7. The angles [3, [3'] can be between 40 and 70°. Preferably, the angles [3, [3'] are on the order of 50° as illustrated in [Fig. 3].
[0043] The sides 76, 76' are oriented towards the bottom 54 (or on a side opposite the external periphery of the cell 5) and are located opposite one of the first lateral support surfaces 62, 62' of the main lobe 6. In particular, the sides 76, 76' are each connected to one of the first lateral support surfaces 62, 62' of the main housing 6 by one of the flat faces 67, 67'.
[0044] One of the features of the invention is that the flanks 76, 76' are each inclined at an angle of inclination α, α' with respect to the plane T7 such that each of the flanks 76, 76' moves away from the opening 52 (or the outer periphery of the cavity 5) as it moves away from the plane PA. The angles of inclination α, α' are said to be negative (unlike the configuration in [Fig. 2]). The angles of inclination α, α' can each be between 1 and 20°. Preferably, the angle α, α' is between 2 and 10°. Advantageously, the angles α, α' are on the order of 5° as illustrated in [Fig. 3].
[0045] As described previously, a blade foot 4 is configured to be fitted into one of the recesses 5 of the rotor disc 1.
[0046] Fig. 4 schematically illustrates an example of a rotor blade foot 4 adapted to the cavity 5 of the disk 1 of the invention.
[0047] The blade 2 has an axis of elongation B (corresponding substantially to the axis A of the disk 1 in the turbomachine 100). The blade 2 comprises an aerodynamic blade 20, one of whose longitudinal ends is connected to a foot 4 by a platform 3 (visible in [Fig. 1]). The blade 2 is formed in one piece. The blade 20 comprises an intrados face, an extrados face, as well as a leading edge 22 and a trailing edge 24. The foot 4 has a median plane of symmetry PA which passes through the axis A.
[0048] The blade foot 4 according to the invention is also of the type with at least two lobes. In the example, foot 4 has two lobes.
[0049] The blade foot 4 is substantially the same shape as the cavity 5 of the disc 1. In particular, the blade foot 4 includes mounting lobes 8, 9 in the housings 6, 7 of the cavities 5. The lobes 8, 9 may be projecting portions having the shape of the housings 6, 7.
[0050] In the example of [Fig.4], the blade foot 4 comprises a first lobe 8 configured to receive the intermediate housing 7, and a second lobe 9 configured to receive the main housing 6 of the cell 5. The first lobe 8 is connected, on the one hand, radially outwards to the platform 3, and on the other hand, radially inwards to the second lobe 9.
[0051] The first lobe 8 comprises two initial support faces 82, 82', two flanks 86, 86', and two necks 84, 84'. Each of the necks 84, 84' connects the first support face 82, 82' to the flank 86, 86'. The first two support faces 85, 82' are located on either side of the plane PB. Similarly, the two flanks 86, 86' and the two necks 84, 84' are each located respectively on either side of the plane PB.
[0052] The first bearing faces 82, 82' are oriented towards the blade 20 and form a third span of the blade 2. These first bearing faces 82, 82' are each inclined in a similar way to the second lateral bearing surfaces 72, 72' of the intermediate housing 7. Indeed, these first bearing faces 82, 82' are inclined with respect to a plane passing through these lateral faces and perpendicular to the axis B, so that these first faces 82, 82' move away from the blade 20 as they move away from the plane PB.
[0053] The sides 86, 86' are oriented on the side opposite the blade 20. These sides 86, 86' are connected to one of the second bearing faces 92, 92' of the second lobe 9 by a flat face. This flat face is inclined with respect to a plane T8, such that this flat face moves away from the blade 2 as it approaches the plane PB. The plane T8 is substantially parallel to the plane T5. The sides 86, 86' are preferably inclined at an angle 0, 0' between 2 and 10°. Advantageously, the angles 0, 0' are on the order of 5° as illustrated in [Fig. 4].
[0054] The second lobe also includes two second bearing faces 92, 92' located on either side of the plane PB. The second bearing faces 92, 92' are oriented towards the blade 20 and form a fourth bearing surface of the blade root. These second bearing faces 92, 92' are each inclined similarly to the first lateral bearing surfaces 62, 62' of the main housing 6. In fact, these second bearing faces 92, 92' are inclined with respect to a plane passing through these lateral faces, so that these second faces 92, 92' move away from the blade 20 as they move away from the plane PB.
[0055] The first and second bearing faces 82, 82', 92, 92' and the flanks 86, 86' can be substantially flat.
[0056] With reference to [Fig.5], we will now describe the rotor 10 of turbomachine 100 comprising at least one blade 2 fitted into one of the recesses 5 of the disk 1 of the invention.
[0057] As described previously with reference to [Fig. 1], the rotor 10 comprises a disk 1 having an axis of rotation which is not visible in the figure. The disk 1 comprises on its outer periphery a plurality of recesses 5 for mounting feet 4 of blades 2. Preferably, the recesses 5 are formed by pinning.
[0058] In particular, during operation in the turbomachine, each of the flanks 76, 76' of the intermediate housing 7 of the cells 5 is distant from one of the flanks 86, 86' of the disk 1, and at least one of the first and second bearing surfaces 62, 62', 72, 72' of the housings 6, 7 of the cells 5 are in contact and abutted with one of the corresponding first and second bearing faces 82, 82', 92, 92' of the blade foot 4. In particular, the first bearing surface of the cell 5 of the rotor disk is abutted against the fourth bearing surface of the blade foot 4 and the second bearing surface of the cell 5 of the disk 1 is abutted against the third bearing surface of the foot 4. In the example of [Fig. 5], all the first and second bearing surfaces 62, 62', 72, 72' of the cells are in contact with the corresponding first and second bearing faces 82, 82', 92, 92' of the blade foot 4. The sides 86, 86', 76, 76' of foot 4 and disc 1 are separated by a maximum clearance J' between 0.10 and 0.50 mm. Preferably, the clearance J' is on the order of 0.25 mm.
[0059] The invention further relates to a turbomachine 100, in particular for aircraft, comprising at least one blade 1 of the invention or at least one rotor 10 of the invention.
Claims
Demands
1. Rotor disk (1) for an aircraft turbomachine (100), the disk (1) having an axis of elongation (A) and comprising on its outer periphery recesses (5) each intended for the insertion of a foot (4) of a rotor blade (2), each of the recesses (5) having a median plane of symmetry (PA) passing through said axis (A) and being of the type with at least two bearing surfaces, each of the recesses (5) comprising: - a lower principal housing (6) having two first lateral bearing surfaces (62, 62') which are located on either side of the plane (PA) and which are oriented towards the outer periphery of the disk and form a first bearing surface of the recess (5), - at least one intermediate housing (7) having two second lateral bearing surfaces (72, 72') which are located on either side of the plane (PA) and which are oriented towards the outer periphery of the disc and form a second span of the alveolus, each of these second surfaces (72,72') being connected by a collar (74, 74') to a flank (76, 76') oriented on the opposite side to the outer periphery of the disc and located substantially opposite one of the first lateral support surfaces (62, 62') of the main housing (6), characterized in that said flanks (76, 76') are inclined with respect to a plane (T7) perpendicular to said axis (A) such that the flanks (76, 76') move away from the outer periphery as they move away from the plane (PA).
2. Rotor disc (1) according to claim 1, characterized in that said flanks (76, 76') are inclined with respect to the plane (T7) by an angle (a, a') between 1 and 20°, preferably between 2 and 10°, and for example of the order of 5°.
3. Rotor disc (1) according to claim 1 or 2, characterized in that said flanks (76, 76') are substantially flat.
4. Rotor disc (1) according to any one of the preceding claims, characterized in that each of said flanks (76, 76') is connected to one of the first bearing surfaces (62, 62') of the main housing (6) by a flat face (67, 67') which moves away from the outer periphery of the disc as it approaches the plane (PA).
5. Rotor disc (1) according to any one of the preceding claims, characterized in that each of said necks (74, 74') has a generally rounded convex shape or comprises a cut face.
6. Turbomachine rotor (10), in particular aircraft rotor, comprising: - a rotor disc (1) according to any one of the preceding claims, - a plurality of rotor blades (2) having a main axis (B) and comprising a blade (20) connected at one of its longitudinal ends to a foot (4) which is intended to be fitted into one of the recesses (5) of the rotor disc (1).
7. Turbomachine rotor (10) according to claim 6, characterized in that each of the blade feet (4) has a median plane of symmetry (PB) passing through said axis (B) and includes mounting lobes (8, 9) inside said housings (6, 7), these lobes (8, 9) include first (82, 82') and second (92, 92') bearing faces opposite, respectively, the first (72, 72') and second (62, 62') lateral bearing surfaces of the housings (6, 7) and bearing on said first (72, 72') and second (62, 62') lateral surfaces, and flanks (86, 86') opposite one of the second bearing faces (92, 92') and at a distance from one of the flanks (76, 76') intermediate housing (7).
8. Turbomachine rotor (10) according to claim 7, characterized in that each of said flanks (76, 76', 86, 86') of the blade foot (4) and of the rotor disc (1) are separated by a maximum clearance (J') of between 0.10 and 0.50mm, preferably 0.25mm.
9. Turbomachine (100), in particular aircraft, comprising at least one disc (1) according to any one of claims 1 to 5 or at least one rotor (10) according to any one of claims 6 to 8.