EP3797213B1 - Assembly of two adjacent angular sectors of turbomachine vane shroud and corresponding vane shroud - Google Patents

Description

The invention relates to an assembly of two adjacent angular sectors of a crown of fixed blades of a turbomachine such as a rectifier fitted to a compressor or such as a distributor fitted to a turbine of the turbomachine.

STATE OF PRIOR ART

Gas turbine engines comprise, in a known manner, crowns of fixed internal blades, which are mounted in external casings of a primary flow stream of the engine and which are interposed axially between movable compressor blade wheels or between mobile turbine blade wheels of these engines. Each ring of fixed blades is mounted with dynamic sealing around a compressor or turbine rotor. For this purpose, each crown of fixed blades internally comprises a block of abradable material which is intended to cooperate with lip seals integral in rotation with the associated compressor or turbine rotor to ensure gas tightness.

A part of the gases is nevertheless likely to insinuate itself between the fixed blades and the movable blades of the compressor or turbine rotors, in the opposite direction to the main flow circulating in the primary flow vein.

The fixed internal blade rings constitute rectifiers when they are interposed between compressor wheels, or constitute distributors when they are interposed between turbine wheels.

In order to facilitate their assembly and reduce their manufacturing cost, the fixed blade crowns are often produced in the form of an assembly of angular sectors which are juxtaposed with each other. next to the others until forming an entire crown of fixed blades. These crowns thus reveal an inter-sector play which leaves recirculation passages for the gases, no longer around the feet of the angular sectors, but between them.

Indeed, conventionally, part of the gases which pass through the fixed blades from upstream to downstream tends to recirculate from downstream to upstream through the seal which is produced between the block of abradable material and the wiper seal. according to a leakage flow rate which we seek to keep as minimal as possible, because it affects the performance of the compressor or the corresponding turbine. Another part of the gases which crosses these blades from upstream to downstream tends to recirculate from downstream to upstream by insinuating itself between the sectors passing through the clearance between the sectors, also called inter-sector clearance.

The difficulty in ensuring a satisfactory level of sealing lies in the fact that the angular crown sectors move due to mechanical and thermal deformations occurring during operation of the engine. Thus, the clearance between sectors and the leakage rate vary during engine operation. The hot clearance during engine operation must also never be zero because contact between the platforms of the sectors could cause an ovalization of the casing which is external to the fixed blade and/or a caulking of the surfaces in contact, this which would risk drastically increasing the stresses exerted on the fixed blade, with the consequence in particular of a transfer of these stresses to the external casing of the engine which receives the fixed blade.

A postponement of these constraints can have the consequence of causing an ovalization of the outer casing and of significantly modifying the radial clearances between this casing and the neighboring moving blades, with a very negative impact for the engine in terms of lifespan.

Conventionally, the sealing between two angular sectors of crown of immediately adjacent fixed blades is ensured by sealing systems with tongues interposed between these sectors in order to limit leaks between sectors. These sealing systems can be used to ensure the sealing of crown sectors of fixed blades placed in the primary flow vein, and also, in the case of a dual-flow engine, to ensure the sealing of sectors crown of fixed blades placed in the secondary flow vein.

According to this technology, tabs are housed between two adjacent sectors in housings which have been machined in the sectors. The tabs make it possible to obstruct the flow of gases passing through the inter-sector clearance.

Conventionally, an angular sector of a blade ring comprises, relative to the axis of the ring, a radially outer platform substantially in the shape of an angular section of a cylinder, a radially inner platform in the form of an angular section of a cylinder, at least two blades which extend between said platforms, a foot linked to the inner platform and at least one block of abradable honeycomb material which extends internally to the foot. The tongues interposed between two sectors are embedded in the mass of the two adjacent legs of the two sectors and in housings opposite the adjacent interior and exterior platforms of the two sectors.

However, these tabs are not easy to assemble. In addition, they require the production of housings in the angular sectors of fixed blades, which have a high manufacturing cost.

Concerning the sealing carried out internally to the interior platform, the tongues cannot be arranged along the entire radial thickness of the foot. Consequently, there remain clearances between the sectors through which the gases can circulate.

There is therefore a need for an alternative sealing technology making it possible to dispense with such tabs and to improve the seal between the fixed blade sectors.

The document FR-2.552.159-A1 describes a technology in which the edges of the interior platforms are shaped according to a Z profile. This configuration improves the effectiveness of the sealing but is limited to the platforms and only applies to a distributor whose block of abradable material n is not sectorized. The document EP 0 017 534 A1 describes a removable seal for a turbomachine distributor segment with the technical characteristics of the preamble of claim 1.

STATEMENT OF THE INVENTION

The invention proposes to take advantage of the existing block of abradable material arranged inside the interior platform to ensure sealing directly between transverse end walls of two adjacent angular sectors.

For this purpose, the invention proposes an assembly of two adjacent angular sectors of the crown of fixed turbine blades as indicated in claim 1.

The block of abradable honeycomb material comprises for example a radially inner radial sealing face which is configured to cooperate with lips of a labyrinth seal carried by a rotor of the turbomachine.

In accordance with the invention, this angular sector is characterized in that the block of abradable material comprises at least one transverse end wall which is shaped according to a toothed profile comprising at least one tooth of radial orientation extending along an entire radial thickness of said block.

• le bloc de matériau abradable s'étend jusqu'à la plateforme intérieure,
• chaque au moins une dent fait saillie transversalement à partir dudit bloc et est réalisée dans ledit matériau abradable en nid d'abeilles dudit bloc,
• le profil denté présente, en section dans un plan perpendiculaire à la direction radiale, une forme en dents de scie,
• le profil denté présente, en section dans un plan perpendiculaire à la direction radiale, une forme crénelée,
• le profil denté comporte une unique dent conformée en tenon,
• l'unique dent conformée en tenon s'étend à partir d'une des extrémités axiales du bloc,
• le matériau abradable en nid d'abeilles du bloc comporte des alvéoles tubulaires orientées radialement.

According to other characteristics of the angular sector:

• the block of abradable material extends to the interior platform,
• each at least one tooth projects transversely from said block and is made of said abradable honeycomb material of said block,
• the toothed profile has, in section in a plane perpendicular to the radial direction, a sawtooth shape,
• the toothed profile has, in section in a plane perpendicular to the radial direction, a crenellated shape,
• the toothed profile has a single tooth shaped like a tenon,
• the single tooth shaped like a tenon extends from one of the axial ends of the block,
• the abradable honeycomb material of the block has radially oriented tubular cells.

The invention finally relates to a crown of fixed blades of a turbomachine comprising a plurality of angular sectors of crown of fixed blades, characterized in that it comprises a determined number of sectors whose juxtaposition forms the entire crown of blades fixed, in that each angular sector has two opposite transverse end walls which are shaped according to toothed profiles each comprising at least one tooth of radial orientation and in that each angular sector is assembled with each of the angular sectors which are attached to it adjacent in an assembly of the type described above.

DESCRIPTION OF FIGURES

• la figure 1 est une vue schématique en coupe d'une turbomachine selon l'état de la technique,
• la figure 2 est une vue de détail en coupe d'une turbine de la turbomachine de la figure 1,
• la figure 3 est une vue en de détail en coupe d'un compresseur de la turbomachine de la figure 1,
• la figure 4 est une vue en perspective d'un assemblage de secteurs angulaires d'aubage selon l'invention,
• la figure 5A est une vue en coupe d'un secteur de couronne d'aubages selon l'état de la technique,
• la figure 5B est une vue en coupe d'un secteur de couronne d'aubages selon l'invention,
• la figure 6 est une vue schématique en coupe d'un premier profil denté d'un bloc de matériau abradable d'un secteur de couronne d'aubages selon l'invention,
• la figure 7 est une vue schématique en coupe d'un deuxième profil denté d'un bloc de matériau abradable d'un secteur de couronne d'aubages selon l'invention,
• la figure 8 est une vue schématique en coupe d'un troisième profil denté d'un bloc de matériau abradable d'un secteur de couronne d'aubages selon l'invention,
• la figure 9 est une vue schématique en coupe d'un quatrième profil denté d'un bloc de matériau abradable d'un secteur de couronne d'aubages selon l'invention.

The invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description which follows, given by way of non-limiting example and with reference to the appended drawings, in which:

• there figure 1 is a schematic sectional view of a turbomachine according to the state of the art,
• there figure 2 is a detailed sectional view of a turbine of the turbomachine of the figure 1 ,
• there Figure 3 is a detailed sectional view of a compressor of the turbomachine of the figure 1 ,
• there figure 4 is a perspective view of an assembly of angular blade sectors according to the invention,
• there figure 5A is a sectional view of a blade ring sector according to the state of the art,
• there Figure 5B is a sectional view of a blade ring sector according to the invention,
• there Figure 6 is a schematic sectional view of a first toothed profile of a block of abradable material of a vane ring sector according to the invention,
• there Figure 7 is a schematic sectional view of a second toothed profile of a block of abradable material of a blade ring sector according to the invention,
• there figure 8 is a schematic sectional view of a third toothed profile of a block of abradable material of a vane ring sector according to the invention,
• there Figure 9 is a schematic sectional view of a fourth toothed profile of a block of abradable material of a blade ring sector according to the invention.

DETAILED DESCRIPTION

In the description which follows, identical reference numbers designate identical parts or having similar functions.

By axial direction, we will designate by extension any direction parallel to an axis A of a turbomachine, and by radial direction any direction perpendicular and extending radially with respect to the axial direction.

We represented at the figure 1 a turbomachine 10 of axis A of the double flow type. Such a turbomachine 10, here a turbojet 10, comprises in a known manner a fan 12, a low pressure compressor (LP) 14, a high pressure compressor (HP) 16, a combustion chamber 18, a high pressure turbine (HP) 20 , a low pressure turbine (LP) 22 and an exhaust nozzle 24. The rotor of the HP compressor 16 and the rotor of the HP turbine 20 are connected by a high pressure shaft HP 26 and form with it a high pressure body. The rotor of the compressor BP 14 and the rotor of the low pressure turbine BP 22 are connected by a shaft BP 28 and with it form a low pressure body.

The high and low pressure bodies are crossed by a primary air flow "P" and the fan 12 produces a secondary air flow "S" which circulates in the turbojet 10, between a casing 11 and an external envelope 13 of the turbojet , in a cold flow channel 15. At the outlet of the nozzle 24, the gases from the primary flow "P" are mixed with the secondary flow "S" to produce a propulsion force, the secondary flow "S" providing here the majority of thrust.

The BP 14 and HP 16 compressors and the HP 20 and BP 22 turbines each respectively comprise several compressor or turbine stages. As illustrated, for example, by figure 2 , the LP turbine 22 comprises several movable blade wheels 22a, 22b, 22c, 22d, 22e of turbine including the blades are carried by associated ferrules 30a, 30b, 30c, 30d, 30e which are assembled to each other by bolts 36.

The LP turbine 22 also comprises fixed blade rings 32a, 32b, 32c, 32d of a diffuser 32 which are interposed between the movable blade wheels 22a, 22b, 22c, 22d, 22e of the turbine.

Each crown of fixed blades 32a, 32b, 32c, 32d of diffuser is formed of an assembly of sectors 34a, 34b, 34c, 34d of crown of fixed blades, assembled around the axis A of the turbomachine over 360° so as to constitute a complete crown of fixed blades 32a, 32b, 32c, 32d around the axis A of the turbomachine.

Likewise, as illustrated by Figures 3 to 5B , the HP compressor 16 of the turbomachine 10 may comprise a series of wheels 22a, 22b of movable compressor blades between which are interposed crowns 32a of fixed rectifier blades which are themselves produced in the form of an assembly of angular sectors 34a of fixed blade crowns. It will therefore be understood that the invention applies to any assembly of angular sectors 34a of crown of fixed blades 32a, whether they are angular sectors 34a of a rectifier intended for a compressor or angular sectors 34a d 'a diffuser intended for a turbine.

As illustrated in more detail in Figure 3 , a crown of fixed blades 32a of compressor is made up of an assembly of angular sectors 34a of crown of blades. We see that each crown of fixed blades, and in particular the crown 32a, is placed in the primary flow vein P forming a clearance with the adjacent compressor wheels 22a and 22b, and in particular with ferrules 30a and 30b of these wheels 22a, 22b. Part of the pressurized gases of the primary flow P, which circulates from upstream to downstream, tends to insinuate itself between the ferrules 30a and 30b and the angular sector 34a to recirculate from downstream to upstream according to a recirculation flow rc, represented by the arrows of the Figure 3 , which tends to bypass the angular sector 34a.

The existence of this rc recirculation flow is particularly penalizing. The recirculation flow rc tends to reduce the performance of the compressor, or similarly when it is a turbine, the performance of said turbine. This is the reason why current designs tend to minimize this recirculation flow rc by equipping the angular sector 34a with sealing means with the ferrule which it surrounds.

As illustrated by Figure 3 , each sector 34a extends at a determined angle around the axis of the crown 32a, which corresponds to the axis A of the turbomachine previously illustrated on the figure 1 .

By "lower", we will designate any positioning close to axis A in the radial direction while by "higher", we will designate any positioning further from axis A in the radial direction than the lower positioning. Finally, by "transverse" we will designate any plane or any surface comprising the axis A and parallel to a section plane of a sector 34.

Conventionally, each sector 34a comprises, relative to the axis A of the crown 32a, a radially outer platform 38a, a radially inner platform 40a, at least two blades 42a which extend between said platforms 38a, 40a, a foot 43a which extends radially inwards from the interior platform 40a and at least one block 44a of abradable honeycomb material which therefore also extends internally to the interior platform 40a between ends transverse (not shown) of the angular sector 34a.

A radially interior radial sealing face 46a is configured to cooperate with lips 48a of a labyrinth seal 50a carried by a rotor of the turbomachine, here the shroud 30a.

This configuration makes it possible to significantly reduce the intensity of the recirculation flow rc circulating between the sector 34a and the ferrule 30a. However, it has no influence on the recirculation flow between two adjacent sectors 34a.

Conventionally, the seal between adjacent sectors 34a is achieved by means of tongues (not shown) which are received in housings facing the adjacent sectors 34a and which are arranged between these sectors 34a to form a barrier to the recirculation flow rc between sectors 34a. This configuration is particularly expensive because it requires making accommodations for the tongues, particularly in the feet 43a, and because it imposes particular assembly precautions, particularly with regard to the sectors which are intended to close the entire blade during of its assembly.

As illustrated by Figure 4 , the invention proposes to simplify the sealing between the sectors 34a by taking advantage of the block 44a of abradable material already present radially inside the interior platform 40a so as to ensure sealing directly between transverse end walls of two adjacent angular sectors.

To this end, as illustrated by figure 4 , the invention proposes an angular sector 34a of a crown of fixed turbine blades of the type described above, characterized in that the block 44a of abradable material comprises at least one transverse end wall 52a which is shaped according to a profile toothed 54a1, 54a2 comprising at least one tooth 56a1, 56a2 of radial orientation R, said at least one radial tooth 56a1, 56a2 extending along an entire radial thickness of said block 44a.

Thus, the figure 4 represents an assembly of two angular sectors 34a of crown of fixed blades. Each of these two angular sectors 34a of fixed blade ring comprises a transverse end wall 52a which is turned towards the transverse end wall 52a of the other sector 34a of fixed blade ring.

As illustrated more particularly by Figure 6 , the block 44a of one of the sectors 34a comprises a toothed profile 54a1 comprising at least one tooth 56a1 and the block 44a of the other of the sectors 34a comprises a toothed profile 54a2, complementary to the toothed profile 54a1, which comprises at least a tooth 56a1. Sealing is therefore ensured in the opposite direction to the primary flow P by the cooperation of the transverse end walls 52a and their complementary toothed profiles 54a1 and 54a2.

The crown of fixed blades 32a comprises a determined number of crown sectors 34a whose juxtaposition forms the entire crown of fixed blades 32a and it comprises at least two of these angular sectors of crown of blades 34a comprising toothed profiles supplementary 54a1, 54a2. It will be understood that obviously, all crown sectors 34a preferably include toothed profiles. Thus, each angular sector 34a is assembled with each of the angular sectors 34a which are adjacent to it in an assembly of the type described above, and each block 44a comprises at its two ends opposite transverse end walls 52a which are shaped according to toothed profiles 54a1, 54a2 intended to cooperate with the toothed profiles 54a1, 54a2 with radially oriented teeth of the adjacent blocks 44a.

In the preferred embodiment of the invention, the block of abradable material 44a of sector 34a extends to the interior platform 40a. This configuration was represented in Figure 5B . Compared to a conventional angular sector 34a like that which was represented in figure 5A , the foot 43a has been removed and the block 44a of honeycomb material has been extended radially to the inner platform 40a so as to give a maximum height to the block 44a of honeycomb material, and in doing so , to give it maximum waterproofing. Furthermore, this configuration makes it possible to dispense with the installation of a conventional sealing system with tabs arranged on the foot 43a.

Preferably, as illustrated in Figure 4 , each interior platform 40a has an end edge 58a which is shaped according to a toothed profile 60a1, 60a2 which is superimposed on the toothed profile 54a1, 54a2 of the corresponding block of honeycomb material 44a. Thus, the toothed profiles 60a1, 60a2 are also complementary to each other. This However, this configuration is not limiting to the invention, and the end edges 58a of the interior platforms 40a could be rectilinear.

Each tooth 56a1 or 56a2 of each block 44a can be produced in different ways. For example, teeth 56a1 or 56a2 could be attached to block 44a, provided that they project from block 44a. However, each tooth 56a1 or 56a2 is preferably made directly from the abradable honeycomb material of block 44a.

The toothed profile 54a1, 54a2 of the block of honeycomb material 44a can take different configurations depending on the desired seal. The higher the number of teeth 56a1 or 56a2, the more the profile 54a1, 54a2 is able to provide a labyrinth making it possible to effectively reduce the flow rate of recirculation flow rc between the adjacent angular sectors 44a. In return, the higher the number of teeth 56a1 or 56a2, the more the adjustment tolerances of two adjacent angular sectors 44a are reduced and the more these adjacent sectors 44a are complex to produce. It will therefore be understood that the number of teeth 56a1 or 56a2 will result from a compromise between the effectiveness of reducing the flow rate of the recirculation flow rc and the cost of obtaining the crown 32a formed from the angular sectors 34a, this cost including the production of these sectors 34a and their assembly.

In this configuration, as illustrated by figures 6 and 7 , the toothed profile 54a1, 54a2 may have, in section in a plane perpendicular to a radial direction R, a crenellated shape, that is to say comprising teeth of substantially rectangular or square section.

Alternatively, as illustrated in figure 8 , the toothed profile 54a1, 54a2 may have, in section in the plane perpendicular to the radial direction R, a sawtooth shape.

Alternatively, as illustrated in Figure 9 , the toothed profile 54a1, 54a2 of each sector 44a may include a tenon which constitutes the single tooth 56a1, 56a2. In this case, the single tooth 56a1, 56a2 shaped like a tenon extends from one of the axial ends 62a1 or 62a2 of the block 44a.

Although this configuration is not limiting to the invention, it will be understood that the abradable honeycomb material of the block 44a comprises tubular cells (not shown) which are oriented radially in the radial direction R. This configuration makes it possible to 'offer maximum resistance to the block of material 44a.

In the preferred embodiment of the invention, the honeycomb material of block 44a is obtained by an additive manufacturing process. This configuration allows the formation of regular cells and a regular conformation of the toothed profiles 54a1, 54a2 without risk of deterioration as could be caused by a material removal process.

The invention therefore advantageously makes it possible to ensure sealing between angular sectors 32a of crown of fixed blades in a simple and effective manner, and to limit the flow rate of the recirculation flow rc between these angular sectors 32a, which makes it possible to significantly improve the performance of a compressor or a turbine equipped with such angular sectors of blade ring 32a.

Claims (9)

1. An assembly of two adjacent angular sectors (34a) of a fixed blade ring (32a) of a turbomachine (10), in particular of a stator vane or a turbine stator, each sector (34a) extending at a predetermined angle about an axis A of the fixed blade ring (32a) and comprising, with respect to the axis A of said fixed blade ring (32a), a radially outer platform (38a), a radially inner platform (40a), at least two vanes (42a) extending between said platforms (38a, 40a), and at least one block of honeycomb abradable material (44a) extending inwardly of the inner platform (38a) between transverse ends of the sector (34a), characterized in that the block (44a) of abradable material of each angular sector (34a) comprises at least one transverse end wall (52a) which is shaped according to a toothed profile (54a1, 54a2) comprising at least one tooth (56a1, 56a2) of radial orientation (R), extending along an entire radial thickness of said block (44a), in that said at least one transverse end wall (52a) of said adjacent angular sectors (44a) face one another, and in that said toothed profiles (54a1, 54a2) are complementary.
2. The assembly of two adjacent angular sectors (34a) according to the preceding claim, characterised in that the block of abradable material (44a) of each angular sector (34a) extends as far as the inner platform.
3. The assembly of two adjacent angular sectors (34a) according to one of the preceding claims, characterised in that each at least one tooth (56a1, 56a2) of each angular sector (34a) projects transversely from said block (44a) and is made of said honeycomb abradable material of said block (44a).
4. The assembly of two adjacent angular sectors (34a) according to one of the preceding claims, characterised in that the toothed profile (54a1, 54a2) of each angular sector (34a) has, in section in a plane perpendicular to the radial direction (R), a saw-tooth shape.
5. The assembly of two adjacent angular sectors (34a) according to one of claims 1 to 3, characterised in that the toothed profile (54a1, 54a2) of each angular sector (34a) has, in section in a plane perpendicular to the radial direction (R), a crenellated shape.
6. The assembly of two adjacent angular sectors (34a) according to one of claims 1 to 3, characterised in that the toothed profile (54a1, 54a2) of each angular sector (34a) comprises a single tooth (56a1, 56a2) shaped like a tenon.
7. The assembly of two adjacent angular sectors (34a) according to the preceding claim, characterised in that the single tenon-shaped tooth (56a1, 56a2) extends from one of the axial end walls of the block.
8. The assembly of two adjacent angular sectors (34a) according to one of the preceding claims, characterised in that the honeycomb abradable material of the block (44a) comprises radially oriented tubular cells.
9. A fixed blade ring (32a) of turbomachine comprising a plurality of fixed blade ring angular sectors (34a), characterised in that it comprises a determined number of sectors (34a), the juxtaposition of which forms the whole of the fixed blade ring (32a), in that each angular sector (34a) comprises two walls (52a) of opposite transverse ends which are shaped in the form of toothed profiles (54a1, 54a2) each comprising at least one radially oriented tooth (56a1, 56a2), and in that each angular sector (34a) is assembled with each of the angular sectors (34a) adjacent to it in an assembly according to one of claims 1 to 8.

Images