FR3137940A1 - Treatment of variable timing casing by co-axial multi-discs - Google Patents

Abstract

The invention relates to an axial compressor of an aeronautical turbomachine comprising at least one rotor wheel adapted to rotate around an axis of rotation (X) and a casing located around the rotor wheel. The casing is provided internally with discs (25) in contact with the fluid, arranged individually perpendicular to the axis of rotation and rotatably mounted relative to each other, around the axis of rotation. Via actuation means (37), slots (31) in the discs can be oriented axially or obliquely relative to the axis of rotation (X). Figure to be published with the abstract: [Fig. 14]

Description

Variable timing crankcase treatment by coaxial multi-discs Technical field of the invention

The invention relates to a casing treatment of an aeronautical turbomachine aimed at controlling the fluid (gas) flow at the tip of blades of a moving wheel, or rotor wheel. More particularly, the invention relates to a compressor casing of this turbomachine and to a compressor of the turbomachine.

In other words, the invention relates to the passive control of the aforementioned gas flow via the technology of “casing treatments”, also called end-wall treatments.

The gaseous fluid flowing generally from upstream to downstream in an aeronautical turbomachine, the "casing treatments" (meaning stator casing) consist of local modifications in the shape of the external envelope of the aerodynamic vein, limited by the casing, around the rotor wheels, and therefore around the axis of rotation of the (each) rotor wheel.

In this text, “axial” has the meaning following, or parallel to, the axis (X hereinafter) of rotation or revolution of a rotor element of the turbomachine, therefore of the aforementioned rotor wheel, and “radial” has the meaning radially (perpendicular) to this axis of rotation which is also the axis of the compressor(s) and the turbine(s). “Axial rotation” designates a rotation around said axis.

State of the prior art

During operation of an aeronautical turbomachine, typically a compressor comprising at least one rotor wheel provided with blades and rotating in a casing forming the outer envelope of the fluid stream to be moved and compressed, a large fluctuation in the fluid flow in the compressor may occur, called compressor surge.

It is known that using “axial slot” type crankcase treatments allows to locally modify the gas flow in the fluid stream and thus influence the appearance of the mechanisms responsible for the compressor starting to surge. An effective crankcase treatment can increase the compressor’s efficient operating range by delaying the appearance of these mechanisms, in particular by reducing aerodynamic blocking at the rotor wheel head.

“Axial slot” type casing treatments typically comprise a series of slots arranged along the radially inner circumference of the casing (in the azimuthal direction) and, radially, around a compressor rotor wheel.

These treatments are non-axisymmetric with respect to the compressor rotation axis. They are therefore frequently called Non-Axisymmetric Crankcase Treatment (or TCNA).

Thus, in this document, a local inner surface, defined by the structural parts that delimit these slots (therefore by the disks which will be discussed below), will be non-axisymmetric, since a section along a plane perpendicular to the axis of rotation will not be circular. More precisely, such a surface will be locally non-axisymmetric since, along the aforementioned radially inner circumference (of each disk), the radius of said surface at the level of the zone considered will vary according to the angle that this radius forms with a vertical axis perpendicular to the X axis of revolution.

The effectiveness of an “axial slot” type crankcase treatment depends on the adequacy between the orientation of the slots and the shape of the flow approaching the pumping zone. Depending on the compressor rotation speed, the shape of the flow changes (classically subsonic at partial speed and supersonic at high speed) and therefore the optimal orientation of the slots is not the same. Also, the optimal orientation of the “upstream” part of the slots is not necessarily the same as the optimal orientation of the “downstream” part of the slots. Simple shapes (straight slots) are therefore not always the best solution for several operating points. A TCNA with “curved” slots, also called “arc” TCNA, has also been proposed where the “upstream” parts of the slots do not have the same timing as the “downstream” parts of the slots.

The respective settings of the upstream and downstream parts of the same slot can be adapted in relation to the flow of the blade head according to the operating regime of the turbomachine. The relative orientation of the flow in relation to the blade in axial rotation is in fact different depending on the regime. The upstream/downstream angles are however usually chosen in relation to the flow at an operating point. Ideally, it would be possible to adapt these slot angles according to each operating regime. However, the constraints of integrating the slots into the casing and controlling the orientation remain major difficulties.

Presentation of the disclosure

The following disclosure aims to overcome such major difficulties and, to this end, applies to an axial compressor of an aeronautical turbomachine comprising:
- at least one rotor wheel adapted to rotate about an axis of rotation of the compressor, in a vein where a fluid can flow, and
- a casing located around the rotor wheel.

More specifically, the present disclosure proposes that this axial compressor comprises a TCNA and is thus such:
- that the casing is provided internally, around the rotor wheel, with a plurality of discs with which the fluid can come into contact and which:
-- are coaxial with the axis of rotation,
-- are arranged individually perpendicular to the axis of rotation,
-- are arranged one after the other along the axis of rotation,
-- are mounted to rotate relative to each other and relative to the housing, around the axis of rotation,
each disc of the plurality of discs defining an internal circumference, around the axis of rotation, and having a plurality of notches distributed around the circumference, and
- that the compressor further comprises means for actuating the disks, adapted to drive together said (i.e. at least some of the) disks around the axis of rotation, the induced rotation of at least one disk relative to the other disks of the plurality of disks making it possible to modify the shape of slots individually created by a series of notches of the plurality of notches located one after the other along the axis of rotation, such that each slot can be presented as:
-- an axial slot, or
-- a slot oriented obliquely to the axis of rotation, in a plane (P1 below) passing through the slot and parallel to the axis of rotation.

This will provide a TCNA crankcase treatment with variable timing slots, this timing being obtained by a coaxial multi-disc solution.

Via such discs attached to the casing, structurally independent of the casing, to their notches, to their capacity for relative movements around the axis of rotation, and to the means of actuating the discs, we have:
- a simple solution for functional integration of the slots “in” the housing,
- a casing that retains its integrity,
- a modular solution offering a wide range of adaptation possibilities with regard to the shape that one wishes to see achieved by the slots, and
- a solution for controlling the orientation of these slots which can therefore be axial or oblique.

Regarding this control of the orientation of the slots, it is proposed:
- that the disks of the plurality of disks are organized successively, along the axis of rotation, from a first disk to a last disk,
- that the disks and the disk actuating means are adapted to drive, in said oblique orientation, all in common, said disks around the axis of rotation, at an angle relative to a parallel to the axis of rotation which is all the more important as one considers said disks, from the first to the last.

This will allow each slot to have a variable, progressive curvature, in one direction or the other, depending on the direction of rotation of the compressor blades.

The aeronautical turbomachine to be considered may be shrouded. But it could also be unshrouded; otherwise of the open-rotor type: Whether the engine is shrouded or not changes nothing in the aerodynamics of the aforementioned axial compressor.

A synonym for the above expression "discs" or "plurality of discs" is "rings" or "plurality of rings". The possibly oblique orientation of the slot is to be understood as including any shape, curved or not, of this slot.

To ensure a functional and practical maneuver to implement, it is proposed that the means of actuating the disks include a connecting rod having:
- a rod passing through said discs and having a first end and a second end, and
- a first articulation and a second articulation, respectively at the first end and at the second end of the rod, the first articulation being in pivot connection with the housing, the second articulation being linked to a piston rod adapted to slide in a piston cylinder in pivot connection with the housing.

So :
- the desired group ordering of disks will be ensured in complete safety and reliability,
- except at the location of the first joint, there will be no interference with the crankcase,
- the crankcase will retain its integrity.

To facilitate ease of maintenance, replacement of all or part of the disks, or even a possible change in the shape that one wishes to see achieved by the slots, it is proposed that the disks of the plurality of disks bear against the housing, without being fixed to it, so that the disks are removable relative to the housing.

In particular, it will be possible to provide peripheral support, via a radially external surface, of the discs against a radially internal surface of the casing then circumferentially surrounding the discs.

For comparable considerations, in particular to facilitate assembly, maintenance, and possible replacement/removal of disks, it is also proposed:
- that the housing (which surrounds the discs) comprises two housing parts joined together, and
- that the discs of the plurality of discs are arranged between the two housing parts.

In connection with such a design of the housing in (at least therefore) two parts, it is also preferably proposed:
- either that, circumferentially around the axis of rotation, the casing comprises two casing sectors joined together, and that the disks of the plurality of disks are, around the axis of rotation, surrounded by a zone of each of said two casing sectors,
- either the housing comprises axially two housing parts joined together, and the discs of the plurality of discs are arranged axially between the two housing parts.

In this way, we will continue on the modular path initiated with the disks, with the concern for ease of assembly/maintenance already expressed.

In any event, surrounding the plurality of discs with a zone (wall) of the casing against which circumferential support of the discs can be achieved will make it possible to combine centering and holding of the discs.

For this purpose, the casing may have, on the radially inner surface, a circumferential groove (in one or more parts) in which the discs will then be engaged, preferably up to the bottom of the groove (radially speaking).

If they do not protrude from the groove, radially inwards (i.e. towards the axis of rotation), the discs will not require modification of the sealing conditions otherwise provided in their environment between the (heads of the) rotor blades and the casing which surrounds them.

And if the notches of the disks are formed in the radially inner circumference of these disks, the resulting slots will then be located in the groove, while being open, radially inward, directly on the gas flow concerned, thus promoting the desired (re)circulation conditions. Indeed, reinjecting, thanks to the slots, gaseous fluid from downstream to upstream, up to upstream of the rotor concerned, makes it possible to re-energize the flow before the rotor, and thus better control the pumping.

Another consideration, compatible with the above, was also to promote the cohesion of the discs, the efficiency of the slots with respect to the gas flow to be obtained, the persistence in the search for simple and reliable solutions, with limited interference with the casing.

It is thus proposed that the axial compressor concerned further comprises spring-effect means for axially stressing the disks, which elastically stress the disks towards each other, parallel to the axis of rotation.

In practice, it will be possible to favor a version in which the spring-effect means for axially stressing the discs will be supported between the casing and the plurality of discs and arranged to stress the discs parallel to the axis of rotation.

Also covered by this disclosure is a shrouded aeronautical turbomachine comprising the compressor which has just been presented, in all or part of its characteristics.

Brief description of the figures

is a half-view in axial section of a ducted aeronautical turbomachine to which the invention can be applied,

is a view of detail II of the ,

is a perspective view of a compressor rotor wheel of the preceding turbomachine surrounded by its casing part equipped with a TCNA with axial slots, according to a first embodiment of the invention;

is a perspective view of one of the disks of the aforementioned TCNA,

corresponds to detail V of the ,

schematizes, locally, a rotor wheel blade head located in front of a series of TCNA disks, while the slots are oriented axially,

schematizes, locally, a rotor wheel blade head located in front of a series of TCNA disks, while the slots are oriented obliquely,

corresponds to detail VIII of the ,

is an axial view of the first two discs of the TCNA, according to arrow IX of the , while the slits are therefore oriented obliquely,

,

, And

illustrate from different angles the proposed TCNA, according to a variant of the housing which surrounds the disks shown compared to the illustrated solution ,

illustrates precisely, to clearly show the difference, the roughly semi-cylindrical half of the crankcase equipped with the TCNA according to the first embodiment of the ,

, And

, illustrate from two different angles a possible embodiment of the means of actuation of the disks of the proposed TCNA, making it possible to drive said disks together around the axis of rotation.

Detailed Description of Disclosure

Before targeting the invention, let us present its environment, which is that of a streamlined aeronautical turbomachine, which can be that of the which illustrates an example of a known axial compression turbojet engine.

The terms upstream (AM) and downstream (AV) are here defined in relation to the direction of circulation of the air or gas flow F. Thus, the air or gas flow F circulating through the turbomachine 1 is directed from upstream to downstream, that is to say from left to right at the .

The turbomachine 1 conventionally comprises, and substantially at the upstream end, a fan 2 downstream of which extends, along the X axis:
- a primary vein 90, annular, in which a primary flow F1 flows, said primary vein passing in particular, in the direction of flow of the primary flow, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6 and a low-pressure turbine 7, the primary vein being delimited externally and along the axis X by a set of fixed casings 8 (stator); and
- a secondary vein referenced 9, in which a secondary flow separate from the primary flow flows, the secondary vein 9 annularly surrounding the primary vein 90.

The secondary vein 9 is itself surrounded by a nacelle 10 forming a fairing for the turbomachine 1.

There illustrates, at the location of reference II of the , in particular the entry zone into the primary vein 90 of said part F1 (primary air) of the air flow F.

There thus schematizes a compressor which, like any compressor, includes at least one compression stage, that is to say a part forming a stator followed by a part forming a rotor.

The low-pressure compressor 3 shown schematically comprises three successive axial compression stages E1, E2, E3, in the example. The illustration could also have shown a high-pressure compressor, such as compressor 4, since the following can also be applied to it.

Each rotor, also called a rotor wheel, comprises a circumferential row of blades 11 extending annularly around the axis X and each radially to it. The rotor blades 11 are connected to a rotor disk (also called a hub) 15 by means of which they rotate around the axis X. Each rotor blade 11 comprises a blade 12, forming the profiled part extending in the primary vein 90.

The stator forming part of each compression stage comprises a row of blades 17 extending annularly around the axis X and each radially to it.

A compression stage is therefore formed by a row of stator blades 17 and the row of rotor blades 11 which is adjacent to it, axially, just downstream.

The blades (typically called “vanes” in English) of each row of stator blades 17 are fixed, at the radially external end 19, to a fixed external shroud 20 belonging to the set of casings 8 and, at the radially internal end 18, to a fixed internal shroud 21. The external shroud 20 and internal shroud 21 are concentric around the axis X.

The external ferrules 20 may be defined by a series of casings 80 of the casing assembly 8.

The blades 11 of each row of rotor blades each have a radially internal end 13 and a free radially external end 16, called a head. Said heads 16 rotate opposite the relevant area of a casing 80.

Thus, the compressor considered includes:
- at least one rotor wheel 23 adapted to rotate around the axis of rotation X, here in the vein 90, and

- a casing 80 of the set of casings 8 located around the rotor wheel.

At its radially internal end 13, each rotor blade 11:
- either has a foot 14 by which the blade 11 is fixed to a rotor disk, by engagement in slots of this disk distributed around its circumference,
- either is monobloc with a disc, in the case of a rotor known under the name “DAM”, monobloc bladed disc, also called “Blisk” (Bladed Disc) or bladed wheel.

The foregoing does not exclude that there may also be a system for variable timing of the blades around their respective radial axes of elongation, such as in particular a system for variable timing of the rectifier vanes 17 (“vanes”) known under the name “Variable Stator Vane (VSV)”. In other words, independently of the manner of connecting the rotor blades 11 to their rotation drive disk 15/15’, FIGS. 3 et seq. make it possible to visualize the solution to the problem that the present disclosure seeks to solve.

So it is illustrated from the :
- at least part of the casing 80, or of the parts which equip it, and facing which the heads 16 of the rotor blades 11 must turn, and
- a compressor with TCNA crankcase treatment of the “axial slots” type.

As explained, the solution of the invention will make it possible to adapt the slot angles according to the operating regimes of the turbomachine, and thus to obtain settings between the upstream and downstream parts of the slots adapted to the flow at the blade head 16, according to the operating regime of the turbomachine. Thus, these upstream/downstream angles will be chosen relative to the flow at an operating point of the turbomachine.

For this, a solution of the invention proposes that, on the compressor part of the aeronautical turbomachine considered, such as therefore at the level of the compressor 3 or 4 of the turbomachine 1, the casing located around the (each) rotor wheel, casing 80 in the example, is provided internally, around the rotor wheel, such as the rotor wheel 23, with a plurality of disks, which can also be called rings, 25 with which the fluid, primary air flow F1 in this case, can come into contact.

All disks, such as 25a, 25b, of the plurality of disks 25:
- are coaxial to the axis of rotation X,
- are arranged individually perpendicular to the axis of rotation X,
- are arranged - grouped - one after the other along the axis of rotation X, and
- are rotatably mounted relative to each other and relative to the casing, casing 80 in the example, around the axis of rotation X.

With respect to the casing, casing 80 in the example, and to the row of rotor blades which they equip, the above disks, such as 25a, 25b, of the plurality of disks 25 are arranged around the heads of the blades 11 of this row of rotor blades.

Hereinafter, reference is made to the same series of such disks. Several compression stages, or several rows of compressor rotor blades may be equipped with the same series of disks 25.

The same plurality of disks 25, and therefore their slots 31, will be advantageously located:
- around the leading edge 110, and the upstream part 111, of the blades 11 to be considered,
- and even around the space 900 of the vein - primary vein 90 here - located just upstream of said blades 11 to be considered.

Each disk, such as 25a, 25b, has a plurality of notches 27 distributed over the circumference C which it defines, around the axis of rotation X.

For ease of handling, each disc, such as 25a, 25b, will preferably be in one piece.

If the disks 25 are maneuvered together in rotation, around the axis of rotation X, by means of disk actuating means 29, the rotation of each disk, such as 25a or 25b, relative to the other disks will make it possible to modify the shape of slots 31 individually created by a series of notches, such as 27a or 27b, of the plurality of notches located one after the other along the axis of rotation, such that each slot 31 can be presented as:
- an axial slot, as shown , Or,
- a slot oblique to the axis of rotation X, as shown .

In other words, circumferentially around the axis of rotation X, each of the disks 25 has a succession of notches 27 which each allow the fluid in question to pass through. And each of these notches 27 is arranged so as to be:
- axially aligned, parallel, to the X axis, with one of the notches 27 of each of the other disks of the plurality of disks 25 (as illustrated ), Or
- angularly offset, around the X axis, relative to one of the notches of at least some of the other disks of the plurality of disks 25 (as illustrated in FIGS. 7 to 9),
such that in any case the flow can pass through all the slots 31 created; see arrows F1 in Figures 6-8, 11 for the slots illustrated.

In the second case, it will be possible in particular, by means of a slot 31, to deflect the flow of fluid by a non-zero angle α such that the slot 31 taken into account extends, relative to a parallel to the X axis, in a biased direction, considered rectilinear like that 31a. . The angle α is defined between a parallel to the X axis at the location of the slot 31 considered (see direction X1 or 10), and the general direction 310 of this slot.

We could also predict that, from one disk 25 to another, this angle α evolves so that the slot 31 considered is arched, or has another shape.

This will allow us to create a non-linear, but curved, slot shape, or even in several successive sections, each linear or not.

In any case, the aforementioned problem of a lack of adaptability of the shape of non-axisymmetric arc-type crankcase treatments according to the operating regime of the turbomachine will thus have been solved. The flow sampling zone, in the F1 flow, of the fluid and the reinjection zone can be optimized to make the crankcase treatment more efficient with respect to the flow, and thus better prevent surges.

Around the axis of rotation X, all the slots 31 of the casing treatment can have, at the same time, the same angle α.

The angle α can typically be between -30° and 30° relative to the X axis, thus covering the two possible directions of rotation of a rotor around the X axis.

The invention makes it possible to adapt the shape of the slots 31 over the entire circumference. The upstream and downstream angles of the slots can be controlled independently using the disks.

The rotation of each disk, considering it in relation to the others, makes it possible to modify the shape of the slots 31 of the crankcase treatment. And the overall setting of these slots 31 is modified by the displacement - the rotation in the azimuthal direction - of all the disks 25.

Let us consider that, in a plane P2 perpendicular to the X axis, we reference β (see ) the angle of deviation, on any one of the disks 25, between:
- a reference frame 29 where the notch concerned belongs to a rectilinear and axial slot 31, and
- the angular position of this notch necessary to obtain an orientation of this slot, and thereby a priori of all the slots, 31 at an angle with respect to a parallel to the X axis, as mentioned above.

On the , the corresponding angle β marks azimuthally the angular variation between a notch 27a of the first disk 25a and the notch 27b of the second disk 25b located just behind it, in the hypothesis where one wishes to obtain a slot 31 oblique with respect to the X axis, as in the .

To obtain an angle α such that the slot 31 taken into account is rectilinear, at an angle, relative to a parallel to the X axis, this angle β will therefore be continuously increasing from the first disk 25a of the plurality of disks - encountered by the flow flowing from upstream to downstream - to the last disk, marked 25f .

Each notch may be formed in the radially inner circumference of the disk 25 considered, which will give the disk a shape with a notched inner circumference and will promote the effect caused on the flow F1 by the passage of the rotor blades.

We can plan:
- between three and one hundred 25 discs (for example 10 discs as in the illustrations); and
- between eight and more than fifty notches on the circumference of each disc 25. An equidistant distribution can be provided; therefore with the same number of slots for the discs considered together.

Increasing the number of discs will reduce the step between two successive disc notches/crenellations, which will improve the surface condition of the slots and therefore the aerodynamic behavior of the crankcase treatment.

A limit to the number of notches, or even to the number of discs, could be the creation of “steps” between successive slotted discs: the resulting crenellated effect deteriorates aerodynamic efficiency.

Each in a plane (such as plane P2) perpendicular to the X axis and arranged axially adjacent to each other, the disks 25 will slide along each other around the X axis.

These disks 25 will preferably each have lateral surfaces, - axially opposed - 250a, 250b, flat, this therefore at the location of their interfaces.

On the radially inner surface 253, and opposite the row of rotor blades 11 considered, the casing has a circumferential groove 35.

The (each) groove 35 is adapted to receive all of the axially adjacent discs 25 of the same series of discs 25.

Correctly engaged in the groove 35, the discs 25 can just be flush with the edges and surfaces, respectively upstream 255a and downstream 255b of the groove 35, which thus define a part of said radially inner surface 253 of the casing. Thus, the general profile defined by the radially inner surface 253 will not be broken by the discs 25.

If each notch 27 is formed in the radially inner circumference of the disk 25 considered, the slots 31 will then be located in the groove 35, while being open, in a radially inner manner, directly onto the flow F1 as shown diagrammatically by way of example. .

To bias the disks towards each other parallel to the axis of rotation X, the compressor may further comprise means 33 which elastically bias the disks 25 towards each other.

In particular, spring-effect means 33 can be provided which press on the discs to hold them.

In order to participate in the common rotational movement of the disks 25 around the axis X, the spring-effect means 33 for axially stressing the disks can be axially active, bearing between the casing, casing 80 in the example, and the first or last disk of the plurality of disks 25, so as therefore to be arranged to stress the disks parallel to the axis of rotation X.

For the same plurality, or series, of disks 25, the spring effect means 33 will then be located in the same groove 35, being circumferentially distributed therein.

As for the disks 25 themselves, it will be useful to connect them physically to the casing, casing 80 in the example, only by pressing against the casing, without them therefore being fixed to the casing, so that the disks 25 can rotate, or even be removable relative to the casing.

The discs 25 will be usefully centered on the axis of rotation X due to the external diameters of the discs 25 which are barely less than the internal diameter of the casing.

In particular, a minimal radial clearance j ( ) which may consist of a quasi-peripheral non-blocking support of the radially external surface 251 of the discs, defined by all of the circumferences of the discs, against a radially internal surface 253 of the casing then circumferentially surrounding the discs.

Around the discs 25, the radially inner surface 253 of the casing will thus itself be advantageously located radially:
- around the leading edge 110, and the upstream part 111, of the blades 11 to be considered,
- and even around the space 900 of the vein - primary vein 90 here - located just upstream of said blades 11 to be considered.

As explained further in this text, one may wish to:
- that the casing, casing 80 in the example, comprises two casing parts 80a, 80b joined together, and
- that the discs of the plurality of discs 25 are arranged between the two parts 80a, 80b of the casing.

Two configurations are then possible, of which figures 10-12 on the one hand and 3.13 on the other hand are possible respective schematic illustrations.

In the first configuration:
- the casing axially comprises said two casing parts 80a, 80b joined together, and
- the discs of the plurality of discs 25 are arranged axially between the two housing parts.

Said two parts 80a, 80b thus form the upstream and downstream parts of the casing respectively.

The discs of the plurality of discs 25 are, around the axis of rotation X, surrounded by a circumferential zone, 820a in the example, of the upstream part 80a of the casing.

A surface of this area defines the bottom 35a of the circumferential groove 35.

The circumferential zone 820a belongs to a circumferential projection 800a towards the downstream side that the upstream part 80a of the casing has and which is axially engaged in an axial recess 800b towards the downstream side that the downstream part 80b of the casing has; the reverse is also possible.

The groove 35 is thus axially defined between two radial walls, respectively of the upstream part 80a and the downstream part 80b of the casing.

In this way, after having engaged the discs 25 axially, one after the other, in the groove part 35 formed by the part of the casing provided with said projection, it will suffice to bring the second part of the casing axially closer to them, until it stops between the projection and the recess.

In the second configuration:
- circumferentially around the axis of rotation X, the casing, casing 80 in the example, comprises at least two casing sectors: two semicircular sectors in section in the example, 810a, 810b, joined together and respectively forming the two aforementioned casing parts, and
- the disks of the plurality of disks 25 are, around the axis of rotation X, surrounded by a circumferential zone, respectively 822a, 822b in the example, of said casing sectors.

Each housing sector will have the corresponding sector of the groove 35, the bottom of which will be formed by the circumferential zones 822a, 822b joined together.

In this way, after having brought the disks 25 axially closer together, one after the other, it will suffice to engage them for example in the sector 810a of the casing, then to arrange the sector 810b around them, until the radial meeting of the casing sectors.

Thus joined together, the casing sectors will be fixed radially to each other by any means, for example screwing; the same for the first configuration in which the meeting is axial.

Arranged as they are, the plurality of disks, 25, must be controlled so that the slots 31 can achieve the desired shape.

To this end, the compressor 3,4 concerned is therefore provided with means 37 for actuating the disks, adapted to drive said disks together around the axis of rotation X; see figures 14, 15, if necessary to be associated with figures 5-11 to visually observe the following.

The rotation of at least one disk, such as 25a, relative to the other disks, such as in particular 25b or 25f, of the plurality of disks, induced by the means 37 for actuating the disks makes it possible to modify the shape of the slots 31 individually created by each series of notches 27 located, one after the other, along the axis of rotation, such that each slot 31 can therefore, as already mentioned, appear in the following manner:
- an axial slot, or
- a slot oriented obliquely (angle α) relative to the axis of rotation X, in a first plane (P1 ):
-- passing through the slot (see section plane IX-IX ), And
-- perpendicular to a second plane (see section plane XX , or plane P2 figures 8,9) radial to the axis of rotation X, which axis X is therefore parallel to the first plane P1.

The disks 25 and the means 37 for actuating these disks are adapted to favorably drive these disks around the axis of rotation X:
- all in common following said oblique orientation, and
- this according to an angle (angle α) relative to a parallel to the axis of rotation which is all the more important as we consider said disks from the first (25a) to the last (25f); this also being true for the angle β with respect to the reference position 29).

To be operational, the means 37 for actuating the disks 25 may include a connecting rod 39 having:
- a rod 41, and
- a first articulation 43a and a second articulation 43b.
The first articulation 43a is in pivot connection with the casing 80. The second articulation is connected to a rod 45a of a piston 45 adapted to slide in a cylinder 45b of the piston. The cylinder 45b of the piston is in pivot connection with the casing 80.

The connecting rod 41 passes through the discs, from the first (25a) to the last (25f), through a common passage 47 provided through each disc in the series.

On either side of the series of discs 25, the first articulation of the connecting rod 39 is located at a first end of the rod 41 and the second articulation 43b at the second end.

Thus, the second articulation 43b connects the rod 41 of the connecting rod 39 and the rod 45a of the piston.

Figures 14 and 15, reference 49 schematizes the shaft by which the cylinder 45b of the piston is in pivot connection with the casing 80.

Claims (11)

Axial compressor of an aeronautical turbomachine comprising:
- at least one rotor wheel (11) adapted to rotate about an axis of rotation (X) of the compressor, in a vein (90) where a fluid can flow,
- a casing (8.80) located around the rotor wheel,
characterized in that:
- the casing is provided internally, around the rotor wheel, with a plurality of discs (25) with which the fluid can come into contact and which:
-- are coaxial to the axis of rotation,
-- are arranged individually perpendicular to the axis of rotation,
-- are arranged one after the other along the axis of rotation,
-- are mounted to rotate relative to each other and relative to the housing (8.80), around the axis of rotation,
each disc of the plurality of discs (25) defining a circumference, around the axis of rotation, and having a plurality of notches (27) distributed over the circumference, and
- the axial compressor (3, 4) further comprises means (37) for actuating the disks, adapted to drive said disks together around the axis of rotation, the induced rotation of at least one disk relative to the other disks of the plurality of disks making it possible to modify the shape of slots (31) individually created by a series of notches of the plurality of notches (27) located one after the other along the axis of rotation, such that each slot can be presented as:
- an axial slot, or
- a slot oriented obliquely (α) relative to the axis of rotation (X), in a plane (P1):
-- passing through the slot (31) and
-- parallel to the axis of rotation (X). Compressor according to claim 1, in which the disks of the plurality of disks (25) are organized successively, along the axis of rotation (X), from a first disk to a last disk, and the disks and the means (37) for actuating the disks are adapted to drive in said oblique orientation, all in common, said disks around the axis of rotation, according to an angle (α) which is all the more important as one considers said disks (25), from the first to the last. Compressor according to claim 1 or 2, in which the means (37) for actuating the disks comprise a connecting rod (39) having:
- a rod (41) passing through said discs and having a first end and a second end, and
- a first articulation (43a) and a second articulation (43b), respectively at the first end and at the second end of the rod, the first articulation being in pivot connection with the casing (8,80), the second articulation being linked to a piston rod (45a) adapted to slide in a piston cylinder (45b) in pivot connection with the casing. Compressor according to one of the preceding claims, in which the discs of the plurality of discs (25) bear against the casing, without being fixed to it, so that they are removable relative to the casing (8, 80). Compressor (12) according to one of the preceding claims, in which the casing (8, 80) has a groove (35) where the discs (25) are engaged without protruding radially. Compressor according to one of the preceding claims, in which:
- the housing comprises two housing parts (80a, 80b; 810a, 810b) joined together, and
- the discs of the plurality of discs (25) are arranged between the two housing parts. Compressor according to one of claims 1 to 5, in which:
- the casing axially comprises two casing parts (80a, 80b) joined together, and
- the discs of the plurality of discs (25) are arranged axially between the two housing parts. Compressor according to one of claims 1 to 5, in which:
- circumferentially around the axis of rotation (X), the casing comprises two casing sectors (810a, 810b) joined together, and
- the discs of the plurality of discs (25) are, around the axis of rotation, surrounded by a zone (822a, 822b) of each of said two casing sectors. Compressor according to one of the preceding claims, which further comprises spring-effect means (33) for axially stressing the discs, which elastically stress the discs (25) towards each other parallel to the axis of rotation (X). Compressor according to claim 9, in which the spring effect means (33) for axially stressing the discs are supported between the casing (80) and the plurality of discs (25) and arranged to stress the discs parallel to the axis of rotation. Aeronautical turbomachine (1) comprising the compressor (12) according to one of the preceding claims.