Low-pressure turbine disc assembly equipped with a notched sealing ring
Patent Information
- Application Number
- FR2023001361
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-02-14
- Publication Date
- 2025-02-21
- Estimated Expiration
- 2043-02-14
Smart Images
Figure 00000012_0000 
Figure 00000012_0001 
Figure 00000013_0000
Abstract
Description
Title of the invention: Disc assembly for low pressure turbine equipped with a notched sealing ring TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a disk assembly for a turbomachine turbine, equipped with a notched sealing ring ensuring the plating of the disks and the movable ring, between two bolted connections, to prevent air leaks between the internal cavity of the turbine and the air circulation vein.
[0002] The invention finds applications in the field of aircraft turbomachines and, in particular, in the field of inter-disc connections of low pressure turbines of turbomachines. TECHNOLOGICAL BACKGROUND OF THE INVENTION
[0003] A turbomachine 10, an example of which is shown in [Fig.l], generally comprises several stages including a fan 11, a low-pressure compressor 12, a high-pressure compressor 13, a combustion chamber 14, a high-pressure turbine 15, a low-pressure turbine 16 and a nozzle 17. The turbomachine 10 is crossed by a primary air flow Fp circulating in a primary vein Vp and a secondary air flow Fs circulating in a secondary vein Vs, outside the primary vein.
[0004] [Fig. 2] represents an example of a low pressure turbine (called LP turbine) of the turbomachine 10. This LP turbine 16 extends around the axis of rotation XX of the turbomachine and comprises a distributor formed of a plurality of fixed blades 166 and a plurality of moving blades 165, mounted by their roots in cells 167 of disks 161 centered on the axis XX. The turbine disks 161 have the main functions of transmitting the torque of the turbine blades to the shaft of the LP turbine (not shown in the figure), of positioning the blades in the secondary flow path Vs and of ensuring the support of sealing parts such as the moving rings 162. An example of a turbine disk 161 is represented in [Fig. 3]. This disc 161, like all turbine discs, has an upstream shell 161a and a downstream shell 161b.The downstream ferrule 161b of a disc 161 is fixed to the upstream ferrule 161a of the consecutive disc 161 (i.e. of the following disc in the direction of flow of the air flow Fp) by means of a bolted connection 163. In particular, the end of each of the ferrules 161a, 161b forms a flange 161c crossed by the bolted connection 163, the flanges and the bolted connection ensuring the holding of two neighboring discs together.
[0005] A connecting ring 162, or movable ring, is disposed between the flanges 161c of the upstream 161a and downstream 161b ferrules. An example of a movable ring 162 is shown on [Fig.4]. This movable ring 162 has the main functions of ensuring the seal between the discs 161 thanks to coated lips 162a, in interface with the abradable fixed on the distributors opposite, of participating in the ventilation of the turbine 16 thanks to ventilation holes 162b and / or lunules 162c. This movable ring 162 comprises a flange 162d housed between the flanges 161c of the upstream 161a and downstream 161b shells and crossed by the bolted connection 163.
[0006] An example of a bolted connection 163 is shown in [Fig. 5]. This bolted connection 163 comprises a nut 163a and a screw 163b passing through a hole 163c formed in the flanges 161c of the upstream 161a and downstream 161b ferrules as well as a hole 163d formed in the flange 162d of the movable ring 162. Thus, each of the upstream 161a and downstream 161b ferrules comprises a ring of holes 163c and the movable ring 162 comprises a ring of holes 163d, these holes 163c, 163d being designed to be opposite each other and passed through by the screws 163b of the bolted connections 163.
[0007] When the turbine 16 is in operation, the bolted connections 163 are exposed to a high centrifugal load and the shells 161a, 161b of the discs 161 are exposed to significant bending stresses. In this configuration, plating defects of the shell flanges 161c and the movable ring flange 162d may appear, generating air leaks. To counter these plating defects, additional tightening operations of the bolted connections 163 have been implemented. However, these tightening operations require approximately 1.5 hours of additional labor in the assembly and maintenance phases, per engine, which results in a significant increase in the assembly cost and the maintenance cost. Furthermore, despite these additional tightening operations, leaks are not completely avoided, which has the effect of significantly reducing the service life of the turbine parts.
[0008] Indeed, to ensure proper operation of the turbine 16, it is essential that the turbine be sealed and that there is a balance between the so-called "fresh" air from the internal cavity Ci of the turbine (also called the upstream purge cavity) and the so-called "hot" air circulating in the primary vein Vp. As shown in [Fig.6], "fresh" air (whose temperature is of the order of 400 to 500°C) is generally taken from the HP compressor 13 in order to cool the disks 161 of the LP turbine and improve their service life. On the contrary, "hot" air (whose temperature is around 1000°C) circulates in the primary vein Vp. A purge of the internal cavity Ci is carried out by rejecting fresh air from the internal cavity Ci towards the primary vein Vp with an air flow, called the purge flow.
[0009] To allow this purging and prevent hot air from entering the internal cavity, the pressure of the “fresh” air in the internal cavity and the purge flow rate must be sufficiently high. However, if due to a plating defect, fresh air escapes from the cavity internal cavity Ci by the bolted connections 163, then the fresh air pressure inside the internal cavity Ci decreases, allowing the hot air from the primary stream Vp to rush into said internal cavity. By entering the internal cavity Ci, the hot air has the effect of heating the discs 161, which has a direct impact on their service life and can even cause the discs to rupture. A diagram shows, in [Fig.7], examples of air leak sections caused by a plating defect in a bolted connection, depending on the different flight phases of the turbomachine. Indeed, the more the turbine is stressed, for example with a high rotation speed, the more noticeable the plating defect is and the larger the air leak section.For example, during the aircraft take-off phase (phase 1), the leakage section can reach 12 mm2; during the aircraft climb phase (phase 2), the leakage section decreases compared to the take-off phase, while remaining high; during the cruise phase (phase 3), the leakage section decreases until it becomes almost zero; and during the aircraft descent or landing phase (phase 4), the leakage section increases again, for example to approximately 4 mm2, until the turbine stops.
[0010] There is therefore a real need for a device making it possible to overcome plating defects in the ferrule and movable ring flanges in order to significantly reduce the leakage section and even eliminate it. Summary of the invention
[0011] To address the above-mentioned problems of air leaks caused by plating defects, the applicant proposes installing a notched sealing ring at the ends of the ferrule and movable ring flanges to envelop the inter-festoon areas between the bolted connections.
[0012] In the description, the term “exterior” designates the surfaces or parts of parts located furthest from the axis of rotation XX of the turbomachine, as opposed to the term “interior” which designates the surfaces and parts of parts closest to said axis XX.
[0013] Furthermore, the terms “upstream” and “downstream” are understood according to the direction of air flow, from the fan of the turbomachine towards the nozzle.
[0014] According to a first aspect, the invention relates to a disk assembly for a turbomachine turbine, comprising: • a first disc comprising a first upstream ferrule and a first downstream ferrule, • a second disc comprising a second upstream ferrule and a second downstream ferrule, • a movable ring mounted between the first downstream shell and the second upstream shell, and • several bolted connections mounted circumferentially at an internal end of the movable ring to hold said movable ring with the first downstream shell and the second upstream shell, characterized in that it further comprises a notched sealing ring, enveloping inter-festoon zones extending between two bolted connections at the junction of the first downstream shell, the second upstream shell and the movable ring.
[0015] The notched sealing ring makes it possible to guarantee sealing in the areas located between two festoons, or two bolted connections, despite plating defects and, thus, to limit air leaks and maintain the purge flow rate sufficiently high.
[0016] The term "notched" in the expression "notched sealing ring" should be interpreted as partially hollowed out or pierced with notches, a notch being an opening creating an empty space between two crosspieces.
[0017] In addition to the characteristics which have just been mentioned in the preceding paragraph, the assembly of discs according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations: • the sealing ring comprises a first and a second circular wall between which crosspieces extend alternating with notches. • the first wall extends circularly along the first downstream shell, the second wall extends circularly along the second upstream shell, each notch is positioned around a scallop zone and each crosspiece is positioned opposite an inter-scallop zone. • the notched sealing ring is hollow and has a U-shaped section at the crosspieces. • the notched sealing ring is fixed around the first downstream shell, the second upstream shell and the movable ring by the bolted connections. • the notched sealing ring is split at the location of a notch. • the notched sealing ring is made from folded and machined sheet metal. • the notched sealing ring has at least one hole positioned in look of a lunula of the mobile ring.
[0018] A second aspect of the invention relates to a low-pressure turbine of a turbomachine, comprising several discs and several movable rings, each movable ring being mounted between two consecutive discs and fixed to said consecutive discs by means of bolted connections. The turbine comprises several disc assemblies according to the first aspect of the invention, the number of disc assemblies being equal to the number of movable rings.
[0019] A third aspect of the invention relates to a turbomachine comprising a low pressure turbine equipped with several disc assemblies according to the first aspect of the invention BRIEF DESCRIPTION OF THE FIGURES
[0020] Other advantages and characteristics of the invention will appear on reading the following description, illustrated by the figures in which:
[0021] [Fig.l], already described, represents a schematic view in longitudinal section of a turbomachine according to the state of the art;
[0022] [Fig. 2], already described, represents a schematic view in longitudinal section of a part of a LP turbine according to the state of the art;
[0023] [Fig. 3], already described, represents a schematic perspective view of a part of a turbine disc according to the state of the art;
[0024] [Fig. 4], already described, represents a schematic perspective view of a part of a moving ring of a turbine according to the state of the art;
[0025] [Fig. 5], already described, represents a schematic view in longitudinal section of a bolted connection of a turbine disk according to the state of the art;
[0026] [Fig. 6], already described, represents a schematic view in longitudinal section of the internal cavity of a LP turbine according to the state of the art;
[0027] [Fig. 7], already described, represents a diagram showing, as a function of the flight phase of a turbomachine, the leakage section generated by a plating defect of a bolted connection according to the state of the art;
[0028] [Fig.8] represents a schematic view in longitudinal section of a bolted connection equipped with a notched sealing ring according to the invention;
[0029] [Fig.9] represents a perspective view of a notched sealing ring according to the invention;
[0030] [Fig. 10] represents a schematic sectional view of a part of a notched sealing ring according to the invention and a diagram of the leakage sections generated by a plating defect as a function of the location considered on the disc assembly for a conventional assembly without the notched sealing ring of the invention; and
[0031] [Fig. 11] represents a partial perspective view of two discs and a movable ring assembled by means of a bolted connection equipped with a sealing fishplate according to the invention.
[0032] In the figures, identical elements are identified by identical references. For reasons of readability of the figures, the size scales between elements represented are not respected. DETAILED DESCRIPTION
[0033] An exemplary embodiment of an LP turbine disk assembly equipped with a notched sealing ring according to the invention is described in detail below, with reference to the accompanying drawings. This example illustrates the characteristics and advantages of the invention. It is however recalled that the invention is not limited to this example.
[0034] An example of a bolted connection of an LP turbine equipped with a notched sealing ring according to the invention is shown in [Fig. 8]. An assembly of discs 164 of an LP turbine 16 comprises several identical bolted connections 163 distributed over the circumference of the assembly 164 and in particular the circumference of the discs 161. The number of bolted connections may, for example, be 54.
[0035] Each bolted connection 163 comprises a screw 163b passing through a hole 163c formed in the flanges 161c of the disc ferrules and a hole 163d formed in the flange 162d of the movable ring 162. The hole 163d of the movable ring flange is positioned between the two holes 163c of the downstream ferrule 161b and the upstream ferrule 161a. The holes 163c of the disc ferrule flanges 161c and the hole 163d of the movable ring flange are called "festoons". The screw 163b therefore passes through the festoon of each of the flanges. The areas of the assembly 164 where the scallops 163c of the ferrules and the scallops 163d of the movable ring are called "scallop areas" and referenced 164c.
[0036] Each bolted connection 163 also comprises a nut 163a screwed to the end of the screw 163b and ensuring, for example by its rectangular shape, the anti-rotation of the screw 163b. Thus the screw 163b is positioned, for example, upstream of the disk assembly 164, that is to say in the vicinity of the downstream shell 161b of a first disk, while the nut 163a is positioned downstream of the disk assembly 164, that is to say in the vicinity of the upstream shell of a second disk, consecutive to the first disk and positioned downstream of the first disk according to the direction of circulation of the air in the turbine. Of course, the positions of the screw 163b and the nut 163a can be reversed, with the screw downstream of the disc assembly 164 and the nut upstream of said assembly 164.
[0037] The bolted connection 163 of [Fig. 8] is equipped with a notched sealing ring 180 according to the invention. An example of a notched sealing ring according to the invention is shown in perspective in [Fig. 9]. This notched sealing ring 180 is a circular part extending over the entire circumference of the disc assembly 164, at the inner end of the ferrules 161a, 161b of the discs 161 and of the flange 162d of the movable ring 162. The notched sealing ring 180 is hollow; it comprises two circular walls 181 which extend parallel to each other. One of these walls 181 extends circularly along the first downstream shell 161b and the other of these walls extends circularly along the second upstream shell 161a. The notched sealing ring 180 also comprises several crosspieces 182 connecting the two walls 181. The crosspieces 182 extend perpendicular to the two walls 181, alternating with notches 183.In other words, the . notched sealing ring 180 is formed of an alternation of crosspieces 182 and notches 183 extending transversely between the two walls 181.
[0038] The notched sealing ring 180 has, at the location of the crosspieces, a U-shaped section designed to fit the discs 161 and the movable ring 162 in their joint end zone 164a, that is to say the zone where the flanges 161c of the disc ferrules and the flange 162d of the movable ring are positioned against each other. The notched sealing ring 180 is designed, in particular, to partially follow the contour of the disc assembly 164 in its internal end zone. Indeed, the notched sealing ring 180 only envelops the inter-festoon zones 164b, the festoon zones 164c being housed in the notches 183 of said sealing ring.More precisely, each crosspiece 182 forms, with the corresponding parts of the walls 181 (i.e. the parts of the walls located on either side of the crosspiece), a U-shaped envelope which can fit around the joint end zone 164a of the disc shells 161a, 161b and the movable ring 162. This U-shaped envelope ensures sealing around the disc shells 161a, 161b and the flange 162d of the movable ring when the plating between said disc shells and the flange of the movable ring is faulty. On the contrary, each of the notches 183 forms an orifice which can receive a scallop zone 164c, i.e. an orifice through which the scallop zone can pass. Thus, the notched sealing ring 180 envelops all of the inter-scalloped areas 164b of the disc assembly 164 and only the inter-scalloped areas.
[0039] According to certain embodiments of the invention, the notched sealing ring 180 is metallic, for example made of sheet metal. It can be produced by bending a metal plate and machining the notches 183, the crosspieces 182 being formed by the metal plate itself after machining the notches. The notches 183 are dimensioned so as to each receive a scalloped area 164c. Each notch 183 has, for example, a circular length L corresponding to the dimensions of a scalloped area 164c. The dimensions of the notch 183 are determined so that the height of the scalloped area 164c emerging from the notch does not interfere with the screw 163b, when mounting the disc assembly 164. The crosspieces 182 are dimensioned so as to each cover an inter-scalloped area 164b.The crosspieces have a circular length D adapted to the dimensions determined for the notches 183 and maximized to generate a maximum plating length on the circumference of the disc assembly 164.
[0040] [Fig. 10] shows a portion of the notched sealing ring 180 mounted on a disc assembly 164. It shows, in particular, two notches 183 crossed by two scalloped areas 164c and a crosspiece 182 enveloping an inter-scalloped area 164b. The inter-scalloped area 164b is positioned between two scalloped areas 164c; similarly, a scallop area 164c is positioned between two inter-scallop areas 164b.
[0041] [Fig. 10] also shows a diagram indicating the sections in mm of the air leaks generated by a plating defect, in a conventional assembly not comprising a notched sealing ring, as a function of the location in the disk assembly 164. This diagram shows in particular that the leak sections depend on the flight phases of the turbomachine. Indeed, the more the turbine is stressed, for example with a high rotation speed, the more noticeable the plating defect is and the larger the air leak section is. The diagram in [Fig. 10] also shows that the largest leak sections are at the inter-festoon zones 164b of the disk assembly 164.Indeed, it can be seen that, in the scalloped areas 164c, that is to say at the locations of the bolted connections 163, the air leaks are relatively low; the plating defects therefore essentially have a consequence in the areas between two bolted connections, that is to say the inter-scalloped areas. The person skilled in the art therefore understands that the notched sealing ring 180 of the invention makes it possible to significantly reduce these leakage sections by ensuring the plating of the disc flanges 161c with the flange 162d of the movable ring between two bolted connections, and therefore by ensuring sealing around these flanges, between two bolted connections.
[0042] The notched sealing ring 180 as described above is secured to the disc assembly 164 by the bolted connections 163. Indeed, the notched sealing ring 180 can be positioned over the entire joint end area 164a of the disc assembly 164 before tightening the bolted connections 163. Once the notched sealing ring 180 is in place, the bolted connections 163 are installed in each scallop area 164c and then tightened in a conventional manner. The notched sealing ring 180 is then held in place by the bolted connections themselves.
[0043] To facilitate the mounting of the notched sealing ring 180 on the joint end zone 164a of the disc assembly 164, said ring may be split over its entire width, preferably at the location of a notch 183. An example of a slot 184 is shown in [Fig.9]. This slot 184 allows the insertion of the notched sealing ring 180 into the disc assembly 164, by means of a twisting of said notched sealing ring. Once the notched sealing ring is inserted into the disc assembly 164, an elastic return of the notched sealing ring allows the positioning of said ring around the scalloped zones 164c, against the inter-scalloped zones 164b. Once the notched sealing ring 180 is mounted in the disc assembly, the centrifugal forces generated by the rotation of the LP turbine ensure that said ring is pressed against the end zone joint 164a.
[0044] In certain LP turbines, the movable ring 162 may be provided with lunules 162e participating in the cooling of the disks of the LP turbine. The lunules are grooves, or windows, made in the flange 162d of the movable ring 162 to allow fresh air to pass through and ensure the cooling of a portion of the disks 161. An example of lunules 162c is shown in [Fig. 4] of the prior art, the lunules of the disk assembly 164 according to the invention being similar to the lunules 162c of [Fig. 4],
[0045] When the movable ring 162 comprises lunules, the notched sealing ring 180 may comprise one or more holes 185 each positioned in the vicinity of a lunule. [Fig. 10] represents an example of a part of a notched sealing ring 180 equipped with such a hole 185. The hole 185 may be produced by machining the walls 181 of the notched sealing ring. The number and location of the holes 185 are directly dependent on the number and location of the lunules in the movable ring; since the holes 185 must not hinder the passage of air through the lunules, they are preferably offset radially relative to the lunules.
[0046] An example of a disc assembly 164 equipped with a notched sealing ring 180 according to the invention is shown in drawing B of [Fig.l 1], in comparison with a disc assembly according to the state of the art shown in drawing A of [Fig.l 1]. This comparison of the two disc assemblies makes it possible to understand that the notched sealing ring 180 is easily inserted onto a conventional disc assembly, without any modification of the discs 161, the movable ring 162 or the bolted connections 163. The notched sealing ring 180 is simply mounted around the joint end areas of the discs and the movable ring and fixed using the original bolted connections.
[0047] Whatever the embodiment (with or without a hole), the notched sealing ring 180 makes it possible to limit the inter-flange leakage sections of the disc assembly 164 and to very significantly reduce the leaks caused by plating defects, which also makes it possible to improve the performance of the LP turbine. The notched sealing ring also makes it possible to save time during assembly and maintenance by avoiding additional tightening operations and / or plating defect checks.
[0048] Although described through a number of examples, variations and embodiments, the LP turbine disc assembly includes various variations, modifications and improvements which will be apparent to those skilled in the art, it being understood that these variations, modifications and improvements are within the scope of the invention.
Claims
Claims
1. Disk assembly (164) for a low-pressure turbine (16) of a turbomachine, comprising: - a first disk comprising a first upstream shell (161a) and a first downstream shell (161b), - a second disk comprising a second upstream shell (161a) and a second downstream shell (161b), - a movable ring (162) mounted between the first downstream shell and the second upstream shell, and - several bolted connections (163) mounted circumferentially at an inner end of the movable ring (162) to hold said movable ring with the first downstream shell (161b) and the second upstream shell (161a), characterized in that it further comprises a notched sealing ring (180), enveloping inter-festoon zones (164b) extending between two bolted connections (163) at the junction of the first downstream shell (161b), the second upstream shell (161a) and the movable ring (162).
2. Assembly according to claim 1, characterized in that the notched sealing ring (180) comprises a first and a second circular wall (181) between which crosspieces (182) extend alternating with notches (183).
3. Assembly according to claim 2, characterized in that the first wall (181) extends circularly along the first downstream ferrule (161b), the second wall (181) extends circularly along the second upstream ferrule (161b), each notch (183) is positioned around a festoon zone (164c) and each crosspiece (182) is positioned opposite an inter-festoon zone (164b).
4. Assembly according to any one of claims 1 to 3, characterized in that the notched sealing ring (180) is hollow and has, at the location of the crosspieces (182), a U-shaped section.
5. Assembly according to any one of claims 1 to 4, characterized in that the notched sealing ring (180) is fixed around the first downstream ferrule, the second upstream ferrule and the movable ring by the bolted connections (163).
6. Assembly according to any one of claims 1 to 5, characterized in that the notched sealing ring (180) is split at the location of a notch (183).
7. Assembly according to any one of claims 1 to 6, characterized in that the notched sealing ring (180) is manufactured from folded and machined sheet metal.
8. Assembly according to any one of claims 1 to 7, characterized in that the notched sealing ring (180) comprises at least one hole (185) positioned opposite a lunule of the movable ring.
9. Low pressure turbine (16) of a turbomachine, comprising several discs (161) and several movable rings (162), each movable ring being mounted between two consecutive discs and fixed to said consecutive discs by means of bolted connections (163), characterized in that it comprises several disc assemblies (164) according to any one of claims 1 to 8, the number of disc assemblies (164) being equal to the number of movable rings (162).
10. A turbomachine comprising a low pressure turbine (16) equipped with several disc assemblies (164) according to any one of claims 1 to 8.