Rotor disc assembly for a gas turbine engine
The gas turbine engine assembly addresses the issue of rear sealing plate lift-off and leakage by using a rear sealing plate with a radially outward sealing surface and segmented blade retaining plates, ensuring a secure and sealed connection, thus reducing leakage and stress on the rotor disk.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROLLS ROYCE DEUT LTD & CO KG
- Filing Date
- 2025-12-12
- Publication Date
- 2026-06-25
AI Technical Summary
Existing gas turbine engine assemblies face issues with the rear sealing plate lifting off the rotor disk under reduced thrust conditions, leading to increased leakage and stress on the rotor disk, and the need for a reliable seal is not adequately addressed.
An assembly comprising a rear sealing plate with a radially outwardly positioned sealing surface and segmented blade retaining plates that fix the rotor blades, ensuring a secure and sealed connection by utilizing anti-rotation structures and sealing wires to prevent leakage and maintain the position of the rear sealing plate.
The solution effectively reduces leakage and stress on the rotor disk by ensuring a secure seal, preventing the rear sealing plate from lifting off and enhancing the connection between the rotor blades and rotor disk, thereby improving the engine's operational stability and efficiency.
Smart Images
Figure EP2025086817_25062026_PF_FP_ABST
Abstract
Description
[0001] Rolls-Royce Deutschland Ltd & Co KG Eschenweg 11 , OT Dahlewitz 15827 Blankenfelde-Mahlow
[0002] RLL369WO
[0003] Assembly for a gas turbine engine
[0004] Description
[0005] The invention relates to an assembly for a gas turbine engine and a gas turbine engine with such an assembly.
[0006] It is known to connect rotor blades to a rotor disk using fir-tree base fixings. A rear sealing plate designed as a ring and blade retaining plates designed as segments serve to axially fix and seal the rotor blades, which are inserted into the fir-tree grooves with their bases.
[0007] The problem is that under reduced thrust conditions, when the rear sealing plate is exposed to cooler air, it can lift off the rotor disk. It reattaches to the rotor disk when the engine thrust increases again. This lifting creates additional leakage. Furthermore, the blade's center of gravity can shift rearward, leading to increased stress on the rotor disk. Another issue is ensuring a reliable seal with the rear sealing plate.
[0008] 2024P00144 WO RLL369WO Page 2
[0009] The present invention is based on the objective of providing an assembly comprising a rear sealing plate, blade retaining plates and a rotor disk, which provides a secure and reliably sealing connection between the blades and the rotor disk.
[0010] This problem is solved by an assembly in a gas turbine engine having the features of claim 1 and a gas turbine engine having the features of claim 21. Embodiments of the invention are specified in the dependent claims.
[0011] In a first aspect of the invention, the invention relates to an assembly in a gas turbine engine comprising a rotor disk, rotor blades, a rear sealing plate, and blade retaining plates. The rotor disk has an axially front side, an axially rear side, and a radially outer side, the radially outer side having axially extending grooves that extend radially from a radially inner end to a radially outer end. Each rotor blade comprises a blade root, the blade roots being positively engaged in the grooves. The sealing plate is annular and abuts the axially rear side of the rotor disk.It comprises an axially front side, an axially rear side, a radially outer region which, with a sealing surface formed on the axially front side, abuts the axially rear side of the rotor disk and the blade roots of the rotor blades inserted into the grooves, thus axially fixing them, and a radially inner region which is fixed to the axially rear side of the rotor disk. The blade retaining plates are segmented circumferentially. They are mounted on the radially outer region of the rear sealing plate at its axially rear side and are designed to protect the radially outer region of the rear sealing plate from hot gas.
[0012] It is further provided that the sealing surface of the rear sealing plate, which serves to axially fix the blade feet, is formed in a radial position on the axially front side of the rear sealing plate, which is closer to the radially outer end than to the radially inner end of the grooves.
[0013] The invention is based on the idea of shifting the position of the sealing surface of the rear sealing plate, which is a sealing contact surface, radially outwards in such a way that blade slot air, which flows into the slots of the rotor disk due to the pressure gradient between the front and back of the rotor disk,
[0014] 2024P00144 WO RLL369WO Page 3 is designed to be sealed as completely as possible by the rear sealing plate, i.e., across the entire radial height of the grooves, so that ideally even cooling air from the blade cooling system is directed axially forward and exits on an axially front side of the rotor disk, thereby reducing the temperature of the rotor disk base. Simultaneously, the rear sealing plate is covered on its axially rear side by the blade retaining plates and thus protected from hot gas, for example, from an adjacent cavity (Jenkinson cavity).
[0015] The present invention thus overcomes the shortcomings of existing axial support systems for blades by preventing or at least reducing the leakage of blade groove air at the rear sealing plate. This, along with the blade support plates covering the rear sealing plate, also reduces the risk of the rear sealing plate lifting off the rotor disk under reduced thrust conditions.
[0016] The axial direction is defined by the engine axis of the gas turbine engine in which the assembly according to the invention is located, with the axial direction pointing from the engine inlet towards the engine outlet. The terms "axial front" and "axial rear" or "front" and "rear" are to be understood in relation to the axial direction, which coincides with the flow direction in the engine. The term "axial front" thus means "upstream" and the term "axial rear" means "downstream". Terms such as "outer" or "inner" refer to the radial direction. Starting from the axial direction, the radial direction points radially outwards.
[0017] According to the purpose of the present invention, which is to displace the position of the sealing surface of the rear sealing plate radially outwards such that blade slot air flowing in the slots of the rotor disk is sealed as completely as possible by the rear sealing plate, the sealing surface of the rear sealing plate is formed in a radial position on the axially front side of the rear sealing plate, which lies at the radially outer end or radially outside the radially outer end of the slots. In this way, it is ensured that blade slot air cannot escape axially to the rear via the rear sealing plate.
[0018] In a further embodiment, the sealing surface of the rear sealing plate is formed on the radially outer boundary edge of the rear sealing plate, i.e., on the radially outermost edge of the rear sealing plate or adjacent to it, so that the sealing surface can assume a maximum radius.
[0019] 2024P00144 WO RLL369WO Page 4
[0020] A further embodiment of the invention provides that the blade retaining plates are fixed radially outwards in structures of the rotor blades and radially inwards in structures of the rear sealing plate. The radially outer structures of the rotor blades, which serve to fix the blade retaining plate, are formed radially inwards on the axially rear region of a blade platform of the rotor blade. By fixing the blade retaining plate in structures of the rotor blades, a feedback effect of forces acting on the blade retaining plate is transmitted back into the rotor blades, which can lead to self-locking and reinforces the desired axial fixation of the blade roots provided by the rear sealing plate.
[0021] The rotor blade structures may be designed to have a first, radially inwardly open groove for fixing the blade retaining plates. This groove is formed at the axially rear end of the rotor blades (or the blade platform), with the radially outer end of each blade retaining plate projecting into this first groove. Furthermore, the blade retaining plates and the rear sealing plate may be arranged with radial clearance such that, when a centrifugal force acts on the blade retaining plates, they move radially outward relative to the rear sealing plate and are pressed into the first groove with their radially outer end. This ensures an optimal seal between the blade retaining plate and the adjacent Jenkinson cavity, thus preventing cooling air flowing through the slots of the turbine disk from escaping into the Jenkinson cavity.
[0022] Another embodiment provides that a sealing wire is additionally arranged in the first, radially inwardly open groove. This sealing wire lies axially in front of the radially outer end of the blade retaining plate and is designed to prevent axial forward movement of the radially outer end of the blade retaining plate. Furthermore, the first groove may have an axially front groove wall and an axially rear groove wall. The axially front groove wall is chamfered and designed to press the sealing wire into the first groove as the rotor disk rotates, thereby pressing the radially outer end of the blade retaining plate against the axially rear groove wall.This optimally seals the blade retaining plate at its radially outer end against the adjacent Jenkinson cavity, thus preventing or reducing the escape of cooling air flowing through the cavities between the outer edge of the turbine disk and the blade platforms into the Jenkinson cavity.
[0023] 2024P00144 WO RLL369WO Page 5
[0024] The sealing wire itself is located in its own cavity, which extends between the axially rear side of the rotor disk and the blade retaining plates, so that it cannot be lost.
[0025] Radially on the inside, the blade retaining plates are fixed to structures of the rear sealing plate. These structures include, for example, a second, radially outwardly open groove formed on the axially rear side of the rear sealing plate, into which the radially inner end of the blade retaining plates projects.
[0026] A further embodiment of the invention provides that the blade retaining plate and the rear sealing plate are in direct contact in axially and radially offset contact areas. Such contact areas are provided, for example, by a first contact area between the axially front side of the blade retaining plate and the axially rear side of the rear retaining plate, located at the radial height of the sealing surface, and a second contact area in the region of the second groove between the axially rear side of the blade retaining plate and an axially rear groove wall of the second groove. The two axially and radially offset contact areas improve the stiffness of the connection between the blade retaining plates and the rear sealing plate.
[0027] According to a further embodiment of the invention, the rear sealing plate forms anti-rotation structures on its axially forward side, which are positively connected to corresponding structures of the rotor disk or rotor blades. These structures prevent unwanted rotation of the rear sealing plate relative to the rotor disk and rotor blades. One embodiment provides that the anti-rotation structures have at least three axially forward-facing projections distributed around the circumference of the rear sealing plate, each of which is fixed in a corresponding recess of a rotor blade root. This ensures circumferential fixation between the rear sealing plate and the rotor blade.
[0028] A further embodiment of the invention provides that the blade retaining plates form anti-rotation structures in their radially outer region, which are positively connected to corresponding structures of the rotor blades. Anti-rotation structures can thus be formed on both the rear sealing plate and the blade retaining plates. One exemplary embodiment provides that the anti-rotation structures have axially rearward-facing projections that are fixed in corresponding recesses of the rotor blades.
[0029] 2024P00144 WO RLL369WO Page 6
[0030] A further embodiment of the invention provides that the rear sealing plate has a stop on its axially front side, radially inward to the sealing surface and opposite each blade root, which limits axial movement of the blade roots. The stop can be designed to press the rear sealing plate against the blade retaining plates and these plates into the structures of the rotor blades and the rear sealing plate to fix the blade retaining plate when a blade root is displaced axially backward. If the rotor blade root displaces axially—unintentionally—it collides with the stop and its axial movement is stopped by it. This is relevant if the force acting on the blade roots via the sealing surface is insufficient to fix the blade roots axially. Upon contact with the stop, further movement is self-locked.
[0031] According to one embodiment of the invention, the blade feet are designed as fir tree feet, which are inserted into correspondingly shaped grooves in the rotor disk. This is a common design for the blade feet.
[0032] A further embodiment of the invention provides that the sealing surface, which rests against the axially rear side of the rotor disk and the feet of the rotor blades inserted into the grooves, extends continuously in the circumferential direction.
[0033] A further embodiment of the invention provides that a radially extending gap is formed in certain areas between the rear sealing plate and the blade retaining plates covering it. This gap reduces heat transfer from the blade retaining plates to the rear sealing plate, thus providing improved protection for the rear sealing plate against high temperatures in the Jenkinson cavity.
[0034] A further embodiment of the invention provides that the blade retaining plates form at least one sealing fin extending axially rearward on their axially rearward side. This is, however, optional.
[0035] The blade retaining plates are segmented circumferentially. They can be designed to abut each other circumferentially, with only a minimal gap or overlapping gap between them to minimize leakage. They extend circumferentially, for example, over two blade roots each.
[0036] 2024P00144 WO RLL369WO Page 7
[0037] Another embodiment provides that a cooling air channel formed in the rotor disk terminates in the slots and is designed and configured to blow cooling air into a gap between the slots and the blade roots. In this way, cooling secondary air, which is taken, for example, from a compressor stage of the gas turbine engine, can be supplied effectively.
[0038] The rotor disk of the assembly according to the invention is, for example, the turbine disk of the rotor of a turbine stage, in particular a high-pressure turbine stage of a gas turbine engine, wherein the principles of the present invention can in principle be implemented on any rotor in a gas turbine engine.
[0039] According to a further aspect of the invention, the present invention relates to a gas turbine engine with an assembly according to one of the preceding claims.
[0040] The invention is explained in more detail below with reference to the figures in the drawing, using several exemplary embodiments. The figures show:
[0041] Figure 1 shows a side section view of a gas turbine engine in which the present invention can be implemented;
[0042] Figure 2 shows a component assembly not relating to the invention for a
[0043] Gas turbine engine comprising a rotor disk, rotor blades attached to it, a rear sealing plate and blade retaining plates;
[0044] Figure 3 shows a top view axially from behind of the assembly of Figure 2;
[0045] Figure 4 shows an embodiment of an assembly for a gas turbine engine comprising a rotor disk, rotor blades attached thereto, a rear sealing plate and blade retaining plates, wherein a sealing surface of the rear sealing plate, which serves to fix the rotor blade feet, is formed on the radially outer boundary edge of the rear sealing plate;
[0046] Figure 5 shows an enlarged view of the assembly of Figure 4, which shows the radially outer area of the rear sealing plate;
[0047] 2024P00144 WO RLL369WO Page 8
[0048] Figure 6 shows a top view axially from behind of the assembly of Figures 4 and 5;
[0049] Figure 7 shows a further embodiment corresponding to the embodiment of Figures 4-6, wherein the blade retaining plates are designed without sealing fins;
[0050] Figure 8 shows a further embodiment of an assembly for a gas turbine engine, comprising a rotor disk, rotor blades attached thereto, a rear sealing plate and blade retaining plates, wherein a sealing surface of the rear sealing plate, which serves to fix the rotor blade roots, is formed on the radially outer boundary edge of the rear sealing plate, and wherein a sealing wire is additionally arranged in a groove which fixes and seals the radially outer end of the blade retaining plates; and
[0051] Figure 9 shows a further embodiment corresponding to the embodiment of Figure 8, wherein the blade retaining plates are designed without sealing fins.
[0052] Figure 1 depicts a gas turbine engine 10 with a main axis of rotation 9, which defines an axial direction of the gas turbine engine. The engine 10 comprises an air inlet 12 and a thrust blower or fan 23, which generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 includes a core 11, which receives the core airflow A. The engine core 11 comprises, in axial flow order, a low-pressure compressor 14, a high-pressure compressor 15, a combustion unit 16, a high-pressure turbine 17, a low-pressure turbine 19, and a core thrust nozzle 20. An engine nacelle 21 surrounds the gas turbine engine 10 and defines a bypass channel 22 and a bypass thrust nozzle 18. The bypass airflow B flows through the bypass channel 22. The fan 23 is attached to the low-pressure turbine 19 via a shaft 26 and an epicycloidal gear 30 and is driven by it.
[0053] In operation, the core airflow A is accelerated and compressed by the low-pressure compressor 14 and directed into the high-pressure compressor 15, where further compression takes place. The compressed air expelled from the high-pressure compressor 15 is directed into the combustion unit 16, where it is mixed with fuel and the mixture is ignited.
[0054] 2024P00144 WO RLL369WO Page 9 is burned. The resulting hot combustion products then spread through and drive the high-pressure and low-pressure turbines 17, 19, before being expelled through the nozzle 20 to provide a certain thrust. The high-pressure turbine 17 drives the high-pressure compressor 15 via a suitable connecting shaft 27. The blower 23 generally provides the main part of the thrust. The epicycloidal gear 30 is a reduction gear.
[0055] It is noted that the terms “low-pressure turbine” and “low-pressure compressor,” as used herein, may be understood to mean the lowest-pressure turbine stage and the lowest-pressure compressor stage, respectively (i.e., excluding the blower 23), and / or the turbine and compressor stages connected by the lowest-rotating connecting shaft 26 in the engine (i.e., excluding the gearbox output shaft driving the blower 23). In some publications, the “low-pressure turbine” and “low-pressure compressor” referred to herein may alternatively be known as the “intermediate-pressure turbine” and “intermediate-pressure compressor.” When using such alternative nomenclature, the blower 23 may be described as a first compression stage or the lowest-pressure compression stage.
[0056] Other gas turbine engines to which the present disclosure may apply may have alternative configurations. For example, such engines may have an alternative number of compressors and / or turbines and / or an alternative number of connecting shafts. As another example, the gas turbine engine shown in Figure 1 has a split-flow nozzle 20, 22, which means that the flow through the bypass channel 22 has its own nozzle, separate from and radially outside the engine core nozzle 20. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass channel 22 and the flow through the core 11 are mixed or combined upstream of (or before) a single nozzle, which may be referred to as a mixing-flow nozzle.One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Although the described example relates to a turbofan engine, the disclosure may be applied, for example, to any type of gas turbine engine, such as an open-rotor engine (where the fan stage is not surrounded by an engine nacelle) or a turboprop engine. In some assemblies, the gas turbine engine 10 may not include a gearbox 30.
[0057] 2024P00144 WO RLL369WO Page 10
[0058] The geometry of the gas turbine engine 10 and its components is / are defined by a conventional axis system comprising an axial direction (aligned with the axis of rotation 9), a radial direction (in the bottom-to-top direction in Figure 1), and a circumferential direction (perpendicular to the view in Figure 1). The axial, radial, and circumferential directions are perpendicular to each other.
[0059] In the context of the present invention, an assembly is important which is implemented in the high-pressure turbine 17 and / or the low-pressure turbine 19 and comprises a rotor of at least one stage of the high-pressure turbine 17 and / or the low-pressure turbine 19. The assembly according to the invention can, in principle, be implemented in at least one turbine stage of any gas turbine engine, with the gas turbine engine 10 of Figure 1 being merely an example.
[0060] For a better understanding of the present invention, before exemplary embodiments of the assemblies according to the invention are explained with reference to Figures 4-9, an assembly which is not designed according to the present invention is first considered with reference to Figures 2 and 3.
[0061] Figure 2 shows an assembly comprising a rotor disk 4, which can also be referred to as a turbine disk. The rotor disk 4 has an axially front side 41 and an axially rear side 42. It further comprises a radially outer side 43 in which axially extending grooves 44 with a fir-tree profile or another profile suitable for a positive-locking connection are formed.
[0062] The assembly further comprises a plurality of rotor blades 3, which are connected to the rotor disk 4 and are circumferentially connected to one another. Each rotor blade 3 has a blade 31, a platform 32, and a root 33. The blades 31 extend in the main flow path of the gas turbine engine. The platforms 32 of the rotor blades 3 together form a radially inner flow path boundary of the main flow path. The root 33 are inserted into the grooves 44 of the rotor disk 4 and thus connect the rotor blades 3 to the rotor disk 4.
[0063] The assembly further comprises a rear sealing plate 5. The rear sealing plate 5 is annular and thus extends only over a defined radial area. The rear sealing plate 5 is attached to the axially rear side 42 of the rotor disk 4. It comprises a radially outer area 51 and
[0064] 2024P00144 WO RLL369WO Page 1 1 a radially inner region 52. On the radially inner region 52, it forms a structure 59 which engages in a recess 45 on the axially rear side 42 of the rotor disk 4 and is fixed therein in the radial and axial directions. The exact manner of fastening the radially inner region 52 with the structure 59 in the recess 45 of the rotor disk 4 is not relevant to the present invention.
[0065] At the radially outer area 51, the rear sealing plate 5 forms a sealing surface 55 which rests against the axially rear side 42 of the rotor disk or the blade feet 33 of the rotor blades 3 inserted into the grooves 44 and is designed and intended to fix these axially.
[0066] The assembly further comprises circumferentially segmented blade retaining plates 6, which are held axially and radially on the radially outer region 51 of the rear sealing plate 5 and are fixed at their radially outer end in a groove 71 on the radially inner side of the platform 32 (where the groove 71 is continuous and formed in the plurality of circumferentially adjacent platforms 32 of the individual rotor blades 3).
[0067] The assembly also includes a stop 49, which prevents or limits axial movement of the blade roots 33 backwards in the respective grooves 44. The stop 49 is part of the rotor disk 4.
[0068] Figure 3 shows the assembly of Figure 2 in a top view from the axial rear to the axial front. The grooves 44 formed in the radially outer region 43 of the rotor disk and the blade roots 33 arranged therein are visible. The blade roots 33 are designed as fir tree roots and are inserted into the correspondingly shaped grooves 44 of the rotor disk 4. It is clearly visible that the axially extending grooves 44 run from a radially inner end 441 to a radially outer end 442. The radially outer end 442 is determined by the radial height at which the fir tree structure of the blade roots 33 terminates. Small gaps 90 and 91 are located between the grooves 44 and the blade roots 33, through which air can flow.
[0069] Figure 3 also shows the rear sealing plate 5, which has a radially outer limiting edge or outer edge 56. The sealing surface 55 is formed radially offset inwards from this edge. A blade retaining plate 6 is also shown, with further blade retaining plates (not shown) extending circumferentially to the one shown.
[0070] 2024P00144 WO RLL369WO Page 12
[0071] Connect the blade retaining plate 6, ensuring that only the smallest possible gap, with or without overlap, exists between the blade retaining plate 6 to minimize leakage. It should be noted that in Figure 3, the sealing plate 5 and the blade retaining plate 6 are shown transparently, i.e., only their outer contours are visible.
[0072] Referring again to Figure 2, arrow B schematically indicates cooling secondary air, which is taken, for example, from a compressor stage of the gas turbine engine, guided through a channel 46 in the rotor disk 4 and blown into the gap 90 between the slots 44 and the blade roots 33 in the area of the slots 44. This air serves to cool the rotor blades 3. However, it is important that the blown-in cooling air – hereinafter also referred to as blade slot air – does not flow unused into the cavity 95 behind the sealing plate. In the assembly shown in Figure 2, this is achieved by the sealing surface 55. However, air can flow from the front of the rotor disk through the gap 91 in the fir tree toothing (above the sealing surface 55) into the cavity 95, as indicated by arrow C, because the sealing plate 5 and the blade retaining plate 6 do not provide sufficient sealing at the axially rear end of the grooves 44.
[0073] Another disadvantage associated with the design shown in Figure 2 is that, under reduced thrust conditions, when the rear sealing plate 5 is exposed to cooler air, it can lift off the rotor disk 4. It reattaches to the rotor disk when the engine thrust is increased again. This lifting action creates additional leakage.
[0074] The assemblies described below with reference to Figures 4-9 avoid or at least reduce the aforementioned disadvantages.
[0075] Figure 4 shows an assembly which, except for the design of the rear sealing plate 5 and the blade retaining plates 6, corresponds to the assembly of Figures 2 and 3. Therefore, with regard to the design of the rotor disk 4 and the rotor blades 5, reference is made to the description of Figures 2 and 3 (although the rotor disk 5 does not form a stop). Figure 5 shows the assembly of Figure 4 in an enlarged view, with the radially outer region 51 of the rear sealing plate 5 and the blade retaining plate 6 shown enlarged. The following description refers to Figures 4 and 5.
[0076] 2024P00144 WO RLL369WO Page 13
[0077] The annular rear sealing plate 5 then abuts the axially rear side 42 of the rotor disk. The rear sealing plate 5 has an axially front side 53 and an axially rear side 54. It further comprises a radially outer region 51 and a radially inner region 52. The radially inner region 52, which is shown only in Figure 4, can be attached to the rotor disk 4 in various ways, for example, by a structure 59 (e.g., a retaining ring) as shown in Figure 2 in a recess 45, or in some other way. The method of attaching the radially inner region 52 of the rear sealing plate 5 to the rotor disk 4 is not relevant to the present invention.
[0078] The radially outer region 51 of the rear sealing plate 5 comprises a circumferential sealing surface 55. The sealing surface 55 is formed on the axially front side 53 of the rear sealing plate 5. It rests against the axially rear side 42 of the rotor disk, or, in the area where the blade roots 33 are inserted into the grooves 44, against the blade roots 33. The sealing surface 55 forms a sealing contact surface. Since it is formed on the radially outer boundary edge 56 of the rear sealing plate 5, and since the radial extent of the rear sealing plate 5 is increased compared to the assembly in Figure 2, the sealing surface 55 now covers the entire radial area in which the blade roots 33 are inserted into the grooves 44. This prevents blade groove air from escaping axially to the rear over the rear sealing plate 55. Rather, it prevents or largely prevents its escape.In contrast, the cooling air for the turbine blade can now enter the cavities 91 via cavity 90 and exit with an axial forward flow direction at the axially forward side 41 of the rotor disk 4. This provides improved cooling of the fir-tree toothing of the rotor disk 4 and the rotor blades 3.
[0079] This is illustrated in Figure 6, which shows the assembly of Figures 4 and 5 in a top view from axial rear to axial front, corresponding to the representation in Figure 3. The sealing plate 5 and the blade retaining plate 6 are transparent, i.e., only their outer contours are shown. The blade roots 33 are designed as fir tree roots and are inserted into the correspondingly shaped grooves 44 of the rotor disk 4. The axially extending grooves 44 run radially from a radially inner end 441 to a radially outer end 442. The radially outer end 442 is determined by the radial height at which the fir tree structure of the blade roots 33 terminates. Small gaps 90 and 91 are located between the grooves 44 and the blade roots 33, through which cooling air can flow.
[0080] 2024P00144 WO RLL369WO Page 14
[0081] As shown in Figure 6, the sealing surface 55 extends directly adjacent to the radially outer boundary edge 56 of the rear sealing plate 5 and is located in a radial position at the radially outer end 442 of the grooves 44. The area in which blade groove air can flow in the region 90 and 91 is thus completely covered by the rear sealing plate 5.
[0082] It should be noted that complete coverage of the overlap area where the blade roots 33 are inserted into the grooves 44 of the rotor disk 4 does not necessarily require the sealing surface 55 to be directly adjacent to the radially outer boundary edge 56. For example, if the radial extent of the rear sealing plate 5 were further increased, the sealing surface 55 could be positioned at a distance from the radially outer boundary edge 56 and still cover the entire overlap area. Generally, the sealing surface is formed in a radial position on the axially forward side of the rear sealing plate 5, which is closer to the radially outer end 442 than to the radially inner end 441 of the grooves 44.
[0083] Referring again to Figures 4 and 5, the blade retaining plates 6 will be discussed in more detail below. These are segmented circumferentially and essentially abut each other directly in the circumferential direction, with only a minimal or overlapping gap provided to minimize leakage. However, the radial extent of these gaps is reduced by the outermost contact surface 55, which contributes to reducing the leakage area. Figure 6 shows such a blade retaining plate 6. The blade retaining plates 6 are mounted on the radially outer region 51 of the rear sealing plate 5 at its axially rear side 54, thus protecting the radially outer region 51 of the rear sealing plate 5 from hot gas.Such hot gas can be present, in particular, in the cavity 95 between the rotor disk 4 and the adjacent structure, also known as the Jenkinson cavity, and, without protection from the blade retaining plates 6, thermally stress the rear sealing plate 5. The blade retaining plates 6 themselves are made of a high-temperature alloy also used for turbine blades. However, this material is not suitable for the sealing plate 5.
[0084] The blade retaining plates 6 are fixed radially outward in structures 71 of the rotor blades 3 and radially inward in structures 72 of the rear sealing plate 5. Thus, a first, radially
[0085] 2024P00144 WO RLL369WO Page 15, an internally open groove 71 is formed. The first groove 71 is formed at the axially rear end of the platform 32. The respective blade retaining plate 6 has a radially outer end 61 and a radially inner end 62. It is inserted into the first groove 71 with its radially outer end 61.
[0086] The blade retaining plates 6 and the rear sealing plate 5 are arranged with radial clearance relative to each other, such that when a centrifugal force acts on the blade retaining plates 6 (when the rotor disk 4 rotates), they move radially outwards relative to the rear sealing plate 5 and their radially outer end 61 is pressed into the first groove 71. The pressure gradient from front to back causes the blade retaining plates to be pressed axially backwards in their outer area 63 against the rear groove surface 712, thus creating a seal.
[0087] The groove 71 has an axially front groove wall 711 and an axially rear groove wall 712. The axially rear groove wall 712 can be seen from its axially rear side in the top view of Figure 6.
[0088] To fix the radially inner end 62 of the blade retaining plate 6, a second groove 72, open radially outwards, is formed in the rear sealing plate 5 on its axially rear side 54, wherein the radially inner end 62 of the blade retaining plate 6 projects into the second groove 72.
[0089] The assembly shown in Figures 4-6 also incorporates anti-rotation structures. Firstly, an anti-rotation structure is provided that prevents the rear sealing plate 5 from twisting relative to the rotor blades 3 and thus also relative to the rotor disk 4. For this purpose, the rear sealing plate has several (at least three) axially forward-facing projections 57 distributed around its circumference, each of which projects into a corresponding recess 36 of a rotor blade root 33. Corresponding structures 57, 36 are shown in Figures 4 and 5 as well as in Figure 6.
[0090] On the other hand, the blade retaining plates 6 can also be provided with anti-rotation structures that prevent twisting relative to the rotor blades 3 or relative to the rear sealing plate 5. Such anti-rotation structures are not shown in Figures 4 and 5, but are shown by way of example in Figure 6. According to this figure, the radially outer end 61 of the blade plate forms an axially rearward-facing projection 67, which is formed in a recess 7120 in the axially rear groove wall 712 of the first groove 71. This, however, is only to be understood as an example. Alternatively, the following could be considered:
[0091] 2024P00144 WO RLL369WO Page 16
[0092] For example, an anti-rotation structure may be provided with an axially forward-facing projection that engages in a corresponding recess in the rotor blades.
[0093] On its axially forward side 53, the rear sealing plate 5 further comprises a stop 58. The stop 58 is located radially inside the sealing surface 55. One stop 58 is arranged opposite each of the blade roots 33. The stop 58 can also be designed as a continuous strip to limit the cooling airflow through cavity 90. The stop 58 serves to stop axial movement of the blade root 33 if the preload provided by the sealing surface 55 is insufficient to prevent axial movement of the blade root 33 in the associated groove 44.
[0094] The stop 58 is designed to press the rear sealing plate 5 against the blade retaining plates 6 and these into the structures 71, 72 of the rotor blades and the rear sealing plate 5 to fix the blade retaining plates 6, thereby fixing the axial position. An additional effect is self-locking against further axial movement, since the radially outer end 61 of the blade retaining plate 6 is again arranged in a structure (the first groove 71) of the rotor blade 3.
[0095] The stop stop 58 is positioned at a slight distance from the radially rear side of the blade feet 33 inserted into the grooves 44 when the blade feet 33 are positioned by the sealing surface 55. Only after a slight displacement of the blade feet 33 in the grooves 44 does a stop against the stop stop 58 occur.
[0096] It is further noted that, as can be seen particularly in Figure 5, a radially extending gap 73 is formed between the rear sealing plate 5 and the blade retaining plates 6 covering it, which reduces heat transfer between the blade retaining plates 6 and the sealing plate 5. The gap 73 extends radially inwards from a contact area 68 in which the blade retaining plate 6 rests flat against the rear sealing plate 5. In the contact area 68, the blade retaining plate 6 on its axially front side 63 and the rear sealing plate 5 on its axially rear side 54 form axially opposing contact surfaces. The contact area 68 is located approximately at the radial height of the sealing surface 55 (which is formed on the axially front side 53 of the front retaining plate 5 opposite the contact area 68).
[0097] 2024P00144 WO RLL369WO Page 17
[0098] The formation of a contact area 68 with opposing contact surfaces of blade retaining plate 6 and sealing plate 5 is relevant in an embodiment in combination with a further contact area 69, in which the axially rear end 64 of the blade retaining plate 6 and an axially rear groove wall 722 of the second groove 72 lie flat against each other, wherein in the contact area 69 the blade retaining plate 6 on the one hand and the axially rear groove wall 722 on the other hand form axially opposing contact surfaces.
[0099] The two contact areas 68, 69 are offset both radially and axially from each other. This leads to an increase and improvement in the stiffness of the connection between the blade retaining plate 6 and the rear sealing plate 5, since, due to the two offset contact surfaces 68, 69, the blade retaining plate 6 and the rear sealing plate 5 cannot tilt relative to each other when the blade retaining plate 6 rests against the axially rear groove wall 722 in the area of the groove 72.
[0100] It should also be noted that in the embodiment shown in Figures 4-6, the blade retaining plate 6 forms one or more sealing fins 65 on its axially rear side 64. However, this is only optional.
[0101] Figure 7 shows an embodiment that corresponds to the embodiment shown in Figures 4-6 except that the blade retaining plate 6 does not form a sealing fin. Accordingly, the axially rear side 64 of the blade retaining plate 6 extends radially. For further details, please refer to the description of Figures 4-6.
[0102] Figure 8 shows an embodiment that essentially corresponds to the embodiment shown in Figures 4-6, but additionally incorporates a sealing wire 8. Specifically, a sealing wire 8 is arranged in the first groove 71, which opens radially inwards (see the explanation of the groove 71 with reference to Figures 4-6). This sealing wire 8 is continuous and circumferential. It is positioned such that it lies axially in front of the radially outer end 61 of the blade retaining plate 6 in the first groove 71, thereby preventing axial forward movement of the radially outer end 61 of the blade retaining plate 6. This ensures that the blade retaining plate is pressed against the rear groove surface 712 to prevent the movement caused by the
[0103] 2024P00144 WO RLL369WO Page 18
[0104] The sealing fin 65 counteracts the resulting forward force at the outer end 61 of the blade retaining plate.
[0105] To enhance this effect, the axially front groove wall 71 1 is chamfered. This causes the sealing wire 8 to be pressed into the first groove 71 along the chamfered front groove wall 71 1 as the rotor disk 4 rotates. This, in turn, causes the radially outer end 61 of the blade retaining plate to be pressed against the axially rear groove wall 712. This further improves the radially outer seal of the blade retaining plate 6. The improved seal towards the axial rear improves the sealing of the air flowing between the outer edge of the rotor disk 4 and the blade platforms.
[0106] Figure 9 shows an embodiment that corresponds to the embodiment of Figure 8 except that the blade retaining plate 6 does not form a sealing fin. Accordingly, the axially rear side 64 of the blade retaining plate 6 extends radially. For further details, please refer to the description of Figure 8.
[0107] It is understood that the invention is not limited to the embodiments described above and that various modifications and improvements can be made without deviating from the concepts described herein. It is further noted that any of the described features can be used separately or in combination with any other features, provided they are not mutually exclusive. The disclosure extends to and includes all combinations and subcombinations of one or more features described herein. Where ranges are defined, these include all values within those ranges as well as all sub-ranges that fall within a range.
[0108] 2024P00144 WO
Claims
RLL369WO Page 19 Patent claims 1. Assembly for a gas turbine engine, comprising: a rotor disk (4) with an axially front side (41), an axially rear side (42) and a radially outer side (43), wherein axially extending grooves (44) are formed in the radially outer side (43) extending radially from a radially inner end (441) to a radially outer end (442), rotor blades (3) each having a blade root (33), wherein the blade roots (33) are positively inserted into the grooves (44), - an annular rear sealing plate (5) which adjoins the axially rear side (42) of the rotor disk (4) and which has: o an axially front side (53) and an axially rear side (54), o a radially outer region (51) which, with a sealing surface (55) formed on the axially front side (53), abuts the axially rear side (42) of the rotor disk (4) and the blade roots (33) of the rotor blades (3) inserted into the grooves (44) and fixes them axially, o a radially inner region (52) which is fixed to the axially rear side (42) of the rotor disk (4), - circumferentially segmented blade retaining plates (6) which are placed on the radially outer area (51) of the rear sealing plate (5) on its axially rear side (54) and are designed to protect the radially outer area (51) of the rear sealing plate (5) from hot gas, - wherein the sealing surface (55) of the rear sealing plate (5) is formed in a radial position on the axially front side (53) of the rear sealing plate (5), which is closer to the radially outer end (442) than to the radially inner end (441) of the grooves (44).
2. Assembly according to claim 1, characterized in that the sealing surface (55) of the rear sealing plate (5) is formed in a radial position on the axially front side (53) of the rear sealing plate (5), which is located at the radially outer end (442) or radially outside the radially outer end (442) of the grooves (44).
3. Assembly according to claim 1 or 2, characterized in that the sealing surface (55) of the rear sealing plate (5) is formed on the radially outer boundary edge (56) of the rear sealing plate (5). 2024P00144 WO RLL369WO Page 20 4. Assembly according to one of the preceding claims, characterized in that the blade retaining plates (6) are fixed radially outside in structures (71) of the rotor blades (3) and radially inside in structures (72) of the rear sealing plate (5).
5. Assembly according to claim 4, characterized in that the structures of the rotor blades (3) for fixing the blade retaining plates (6) have a first radially inwardly open groove (71 ) which is formed at the axially rear end of the rotor blades (3), wherein the radially outer end (61 ) of the respective blade retaining plate (6) projects into the first groove (71 ).
6. Assembly according to claim 5, characterized in that the blade retaining plates (6) and the rear sealing plate (5) rest on each other with a radial clearance such that, when a centrifugal force acts on the blade retaining plates (6), they move radially outwards relative to the rear sealing plate (5) and are pressed into the first groove (71) with their radially outer end (61).
7. Assembly according to claim 5 or 6, characterized in that the first groove (71 ) has an axially front groove wall (71 1 ) and an axially rear groove wall (712), wherein the axially front groove wall (711 ) is chamfered and designed to press a sealing wire (8) into the first groove (71 ) when the rotor disk (4) is rotated, thereby pressing the radially outer end (61 ) of the blade retaining plate (6) against the axially rear groove wall (712).
8. Assembly according to one of claims 4 to 7, characterized in that the structures of the rear sealing plate (5) for fixing the blade retaining plates (6) have a second, radially outwardly open groove (72) which is formed on the axially rear side (54) of the rear sealing plate (5), wherein the radially inner end (62) of the respective blade retaining plate (6) projects into the second groove (72).
9. Assembly according to one of the preceding claims, characterized in that the blade retaining plate (6) and the rear sealing plate (5) are in direct contact in axially and radially offset contact areas (68, 69).
10. Assembly according to claim 9, insofar as it relates back to claim 8, characterized in that a first contact area (68) between the blade retaining plate (6) and the rear sealing plate (5) at radial height of the sealing surface (55) between the axially front side (63) of the blade retaining plate (6) and the axially rear side (54) of the rear retaining plate (5) and a second contact area 2024P00144 WO RLL369WO Page 21 (69) between the blade retaining plate (6) and the rear sealing plate (5) in the area of the second groove (72) between the axially rear side (64) of the blade retaining plate (6) and an axially rear groove wall (722) of the second groove (72). 1 1. Assembly according to one of the preceding claims, characterized in that the rear sealing plate (5) forms anti-rotation structures (57) on its axially front side (53) which are positively connected to corresponding structures (36) of the rotor disk (4) or the rotor blades (3).
12. Assembly according to one of the preceding claims, characterized in that the blade retaining plates (6) form anti-rotation structures (67) in their radially outer region which are positively connected to corresponding structures (7120) of the rotor blades (3).
13. Assembly according to claim 12, characterized in that the anti-rotation structures (67) have axially directed projections.
14. Assembly according to one of the preceding claims, characterized in that the rear sealing plate (5) has a stop stop (58) on its axially front side (53) radially inside to the sealing surface (55) and opposite each blade root (33), which limits an axial movement of the blade roots (33).
15. Assembly according to claim 14, insofar as related backwards to claim 4, characterized in that the stop stop (58) is designed to press the rear sealing plate (5) against the blade retaining plates (6) and these into the structures (71 , 72) of the rotor blades (3) and the rear sealing plate (5) to fix the blade retaining plates (6) when stops of an axially rearward displaced blade root (33).
16. Assembly according to one of the preceding claims, characterized in that the sealing surface (55), which abuts the axially rear side (42) of the rotor disk (4) and the blade feet (33) of the rotor blades (3) inserted into the grooves (44), extends continuously in the circumferential direction.
17. Assembly according to one of the preceding claims, characterized in that a radially extending gap (73) is formed between the rear sealing plate (5) and the blade retaining plates (6) covering it. 2024P00144 WO RLL369WO Page 22 18. Assembly according to one of the preceding claims, characterized in that the blade retaining plates (6) each form an axially rearward extending sealing fin (65) on their axially rearward side (64).
19. Assembly according to one of the preceding claims, characterized in that the blade retaining plates (6) adjoin or overlap each other in the circumferential direction.
20. Assembly according to one of the preceding claims, characterized in that a cooling air channel (46) formed in the rotor disk (4) terminates in the grooves (44) and is designed and configured to blow cooling air into a gap (90) between the grooves (44) and the blade roots (33).
21. Gas turbine engine with an assembly according to one of the preceding claims. Claims. 2024P00144 WO