FR3098743A1 - MANUFACTURING PROCESS OF A STATORIC STRUCTURE WITH ABRADABLE INSTRUMENT - Google Patents

Abstract

The invention relates to a method of manufacturing a stator structure for a turbomachine, the method comprising the steps of: a) providing a stator part delimited by a proximal surface intended to extend opposite a rotor part of a turbomachine, this stator part comprising a housing which opens onto the proximal surface; b) fixing on the stator part, within the housing, at least one measuring instrument; and c) filling the housing by depositing and agglomerating a powder to form a block of abradable material. The invention also relates to a turbomachine including: an assembly comprising a rotor part and a stator structure which includes a stator part delimited by a proximal surface extending vis-à-vis the rotor part, this stator part being provided with 'a housing opening onto the proximal surface, the stator structure comprising at least one measuring instrument arranged in the housing by being fixed to the stator part, and a block of abradable material filling the housing by trapping said at least one measuring instrument, this block of abradable material consisting of an agglomeration of powder; and - a computer configured to receive and process acquisition data from said at least one measuring instrument.

Description

METHOD FOR MANUFACTURING AN INSTRUMENTED ABRADABLE STATOR STRUCTURE

The present invention relates to a method for manufacturing a turbomachine stator structure comprising a block of abradable material, this type of material being used as a seal facing a rotor part. Furthermore, the invention relates to a turbomachine comprising such a stator structure.

In order to meet the increased performance needs of turbomachines, engine manufacturers tend to limit losses by leaks, these leaks designating fractions of flow passing through narrow passages, between rotating parts, called rotor parts, and fixed or stator parts facing each other. screw. These losses alter the energy exchanges with the circulating flow, ie minimize the compression ratios through the compressors and the useful mechanical work in the turbines. Concretely, these losses limit the thrust generated by the turbomachine while increasing its fuel consumption per kilogram transported. In particular, within turbomachine compressors, significant leaks cause pressure instability, which can in the most critical case lead to a shutdown of the turbomachine by reversal of the conventional direction of the flow, called the "pumping" phenomenon.

This problem of reducing losses by leaks is complex because the turbomachine is the seat of significant variations in flow temperatures depending on the operating regimes, which leads to a dimensional variation by expansion of the rotor and stator parts. The expansion being a function of the temperature, of the coefficient of expansion intrinsic to the materials used, and of the initial dimensions of the components, the clearance measured between the associated stator and rotor parts is generally not athermal, in other words is not constant in all the temperature range under the effect of differential rotor/stator expansion. It follows that a clearance initially optimized to reduce leakage to an acceptable level for a given temperature, can be reduced to the point of becoming zero and generating friction, or even negative, resulting in the blocking of the rotor, from English “rotor lock”. In particular, in the case of a bladed rotor part, the elastic elongation of the blades, under the action of the centrifugal forces to which they are subjected at high rotational speeds, exacerbates this problem of interaction with the stator.

To satisfy this dual condition, namely to minimize the rotor/stator operating clearances without leading to a destructive effect, motorists mainly adopt the use of so-called “contactless” dynamic seals. In the case of a rotor/stator pair formed by a bladed wheel surrounded by a fixed casing, this seal takes the form of a soft coating placed on the casing and in line with the blades. Formed of an abradable material, that is to say with dislocation capacity, this coating is a sacrificial consumable intended to be hollowed out by the ends of the blades without damaging them, while forming an interface which protects the casing from friction. and/or impacts with these blades.

Ideally, the blades act as cutting tools that machine the coating until optimal clearance is stabilized from the first turns of the rotor break-in under different operating regimes, leaving a smooth coating surface ensuring good aerodynamic performance.

Nevertheless, it happens that certain operating hazards of the turbomachine lead to undesirable blade/coating interactions due to transient variations in geometry. Among the various events identified, stand out in particular the imbalance of the rotor induced by certain piloting maneuvers or turbulence in flight, the aspiration of foreign bodies, the ovalization of the casing by rapid and significant variation in the altitude of the aircraft , or the rotor/stator resonance phenomenon. The multiplication of these interactions creates excessive wear of the coating, which leads to the loss of control of the tightness by amplification of the operating clearances and, consequently, to a drop in the instantaneous efficiency of the turbomachine.

Also, the mechanical and physico-chemical performances of the coating are likely to be altered by friction and repeated heating: the said coating becomes more sensitive to the mechanisms of wear by erosion and corrosion leading quickly to ruin, and loses in degree of abradability, ie becomes denser, to the point of damaging the blades.

Knowing that the operating conditions differ from one turbomachine to another, the same applies to the occurrence of these interaction phenomena. It follows that the estimated average lifetime of the coating is subject to large variations. This situation leads to a multiplication of maintenance operations aimed at checking the wear and material health of the coating and the blades. These maintenance operations are long and systematically lead to the removal of the turbine engine, i.e. additional costs of immobilization of the aircraft which is equipped with it.

The object of the invention is to provide a solution making it possible to remedy this drawback.

To this end, the subject of the invention is a method for manufacturing a turbomachine stator structure, the method comprising the steps of:
a) supply of a stator part delimited by a proximal surface intended to extend opposite a turbomachine rotor part, this stator part comprising a housing which opens onto the proximal surface;
b) fixing on the stator part, within the housing, of at least one measuring instrument; And
c) filling the housing by deposition and agglomeration of a powder to form a block of abradable material.

With this solution, the measuring instrument is able to collect in situ data allowing faithful control of the material health of the abradable material. The lifespan of the block of abradable material can be assessed in real time and maintenance steps can be reduced as needed.

The invention also relates to the method thus defined, in which step b) comprises gluing or a mechanically welded assembly of the measuring instrument or of each measuring instrument to the stator part.

The invention also relates to the method thus defined, in which in which the housing of the stator part provided in step a) is blind, and the measuring instrument or each measuring instrument can be used wirelessly.

The invention also relates to the method thus defined, in which the measuring instrument or at least one of the measuring instruments is wired, and the housing of the stator part provided in step a) comprises a conduit which guides the cable from the measuring instrument or said at least one of the measuring instruments outside the stator part.

The invention also relates to the method thus defined, in which step c) comprises vacuum filling of the housing with the powder, then agglomeration of the powder by sintering.

The invention also relates to the method thus defined, in which step c) is implemented by additive manufacturing. In this respect, the invention advantageously provides for using the technique of laser fusion by powder spraying, or the technique of cold spraying at supersonic speed.

The invention also relates to a turbomachine assembly comprising a rotor part and a stator structure which includes a stator part delimited by a proximal surface extending opposite the rotor part, this stator part being provided with a housing leading to the proximal surface,

the stator structure comprising at least one measuring instrument arranged in the housing while being fixed to the stator part, and a block of abradable material filling the housing by trapping said at least one measuring instrument, this block of abradable material being made up of an agglomeration of powder.

The invention also relates to an aircraft turbine engine comprising an assembly thus defined, and a computer configured to receive and process acquisition data from said at least one measuring instrument.

The invention also relates to an aircraft turbine engine thus defined, comprising an on-board computer configured to automatically regulate the operation of the turbine engine as a function of a result of processing the acquisition data of said at least one measuring instrument by the computer .

With this solution, the turbomachine performs a function of controlling and regulating its operation according to the acquisition data of said at least one measuring instrument.

The invention also relates to a turbomachine thus defined, in which the stator part is a turbine or compressor casing, and the rotor part is a rotating blade.

is a diagram in axial section of a turbomachine with a function of controlling and regulating its operation according to acquisition data from measuring instruments trapped in a block of abradable material with a stator structure;

is a schematic view in axial section of a turbine or a compressor of the turbomachine of FIG. 1;

shows a sectional view of a stator part, along a plane passing through the axis of rotation of a facing rotor part, including a housing provided to contain a block of abradable material instrumented in accordance with the method according to invention;

illustrates a step for installing measuring instruments in the housing of FIG. 3 in accordance with the method according to the invention;

illustrates a step of filling the housing of FIG. 4 equipped with measuring instruments with powder provided to constitute the block of abradable material in accordance with the method according to the invention;

illustrates a step of isostatic compression of the powder filling the housing of FIG. 5A to form the block of abradable material in accordance with the method according to the invention;

illustrates a step of forming the block of abradable material by additive manufacturing within the housing of FIG. 4 equipped with measuring instruments in accordance with the method according to the invention.

DETAILED EXPLANATION OF PARTICULAR EMBODIMENTS

Turbomachinery

Referring to Figure 1, there is shown an aircraft turbine engine 1, according to a preferred embodiment of the invention. This is a dual-spool turbofan engine. Nevertheless, it could be a turbine engine of another type, for example a turboprop or a turbine engine, without departing from the scope of the invention.

The turbomachine 1 has a central axis AX around which its various components extend. Throughout this description, the longitudinal direction is the direction of the AX axis. The radial direction, defined by the axis AY, is at all points a direction orthogonal to the axis AX and passing through this axis, and the circumferential direction marked by AZ is at all points a direction orthogonal to the radial and longitudinal directions. Also, the terms “upstream” AM and “downstream” AV are to be considered according to the longitudinal direction and in particular the main direction of gas flow within the turbomachine, denoted S. Finally, the terms “internal” and “external” refer respectively to a relative proximity, and a relative remoteness, of an element with respect to the axis AX in the radial direction.

The turbomachine conventionally comprises a gas generator 2. This gas generator 2 comprises a combustion chamber 3 on either side of which are arranged low-pressure 4 and high-pressure 6 compressors upstream AM, and high-pressure turbines pressure 7 and low pressure 8 downstream AV along the axis AX.

It comprises, upstream of the gas generator 2, a fan 9 which comprises a series of fan blades 10 of large dimensions, spaced apart circumferentially and extending in the radial direction. The fan 9 is surrounded radially by a fixed fan casing 11 centered on the axis AX. Close downstream of the fan 9, the turbomachine defines a primary stream 12 and a secondary stream 13 between which extends an engine compartment 14, commonly called the “core” compartment. The secondary stream 13 radially surrounds the primary stream 12 while also being delimited on the outside in part by a shroud 16 extending the fan casing 11 downstream. The air propelled by the fan is thus divided into a primary flow Fp which crosses the primary vein 12 to supply the gas generator 2, and a secondary flow Fs which is ejected directly downstream by traveling in the secondary vein 13.

Referring to Figure 2, which generically illustrates the architecture of the compressors 4, 6 and turbines 7, 8, the compression and expansion steps are ensured by the cooperation of a rotor, including a rotating shaft centered on the axis AX carrying rotor blades 17, with a stator comprising a casing 15 carrying stator vanes 18. In particular, the casing 15 comprises an internal surface 15a which delimits the primary vein 12 radially outwards, and an external surface 15b which delimits the engine compartment 14. As it is understood, the casing 15 denotes either a turbine casing or a compressor casing, separating the primary stream 12 from the engine compartment 14.

In practice, these compressors 4, 6 and turbines 7, 8 can be perceived as a succession of stages, each stage of which comprises a circumferential row of rotor blades 17 and a circumferential row of stator blades 18 designated by the terms " rectifier" or "distributor". In this example, the rotor blades 17 each comprise a blade 19, a root 21 which engages in a disc 22 extending radially from the shaft, and a platform 23 which connects the root 21 to the blade 19. This platform 23 in particular delimits the primary vein 12 radially inward. As regards the stator vanes 18, they each comprise a blade 24 extended on either side of its radial ends by a radially inner platform 26 and a radially outer platform 27 which jointly delimit the primary stream 12. In particular, these stator vanes 18 are held in position both by bulbs 28 which protrude from the radially outer platform 27 to be anchored in the casing 15, and by an inner shroud 29 which supports the radially inner platform 26.

Certain stator parts of the turbomachine 1 are equipped with a block of abradable material H positioned opposite the rotor parts marked by a small rotor-stator clearance and therefore susceptible to interactions. According to the invention, a block of abradable material H incorporates a housing which extends circumferentially in the fan casing 11 and which opens onto its internal surface 11a, namely facing the fan 9, and in line with the blades 10. Similarly, the turbines and compressor are equipped with blocks of abradable material H provided in housings which are formed circumferentially in the corresponding casing 15 and which open onto the internal surface 15a, in line with the rows of rotor blades 17. Additionally, the inner shroud 29 is equipped with a block of abradable material H against which wipers 30 carried by the rotor slide.

The basic idea of the invention is to provide the turbomachine 1 with a function for controlling the health of the material and the behavior of the abradable material H and the rotor parts facing each other, from the English "Structural Health Monitoring”. In this respect, the major particularity of the invention resides in a method of manufacturing a stator structure with an instrumented abradable.

Manufacturing process

Subsequently, the manufacturing process will be described generically on the basis of a stator part S intended to extend opposite a rotor part R. It is understood that this stator part can equally well designate the casing 15 at the level of the turbines and compressors, the fan casing 11, the inner shroud 29, or any other so-called stator part intended to be equipped with a block of abradable material facing a rotor part that the person skilled in the art could consider . Additionally, the rotor part can designate, without limitation, a rotor blade 19, a fan blade 10, a rotor blade or a wiper 30 carried by the rotor.

Referring to Figure 3, the arrangement of the method according to the invention requires a step consisting in forming a housing 31 in the stator part S. This housing 31, provided to contain the block of abradable material, is intended to extend in the extension of the rotor part R capable of engaging inside in operation, as illustrated in dotted lines in FIG. 3. By way of example, this housing 31 is provided to extend circumferentially when the stator part designates a casing 15 of the turbine/compressor or fan casing 11.

This housing 31 is a hollow volume which opens onto a so-called proximal surface S1 of the stator part S, defined as its surface facing the rotor part R. In other words, the volume of the housing is defined between the resulting wall of the recess of the stator part and a plane P1 corresponding to the proximal surface S1 before the recess. In the case of the turbine/compressor casing 15 or of the fan casing 11, this surface S1 denotes their respective internal surface 15a and 11a.

Once the housing 31 has been made, the method according to the invention provides for the integration within it of the measuring instruments. These instruments designate any type of sensors/detectors whose acquisition data makes it possible in particular to identify and quantify a rotor/stator interaction, to evaluate the physico-chemical properties of the abradable material, and thus also to control the integrity of the rotor part. The instruments can also inform certain operating conditions of the turbomachine at their destination location.

By way of non-limiting example, it may be desired to place:

- stress/deformation gauges making it possible to highlight a deterioration in the mechanical strength of the abradable material;

- thermometers making it possible to identify an interaction via a significant rise in the temperature of the abradable material, and to warn of a possible alteration of its physico-chemical properties which could lead to damage to the rotor part, in particular if the temperature exceeds a plastification threshold of the abradable material;

- pizeoelectric sensors making it possible to control in particular the depth of incursion of the rotor part within the abradable material, namely to measure the rotor-stator operating clearance;

As visible in Figure 4, these instruments, denoted 32, are rigidly fixed on the stator part S, at the level of the periphery of the housing 31. They are placed and oriented at specific angles so as to extend fairly close to the part. rotor to faithfully deliver data as close as possible to the true value, without encountering the opposite rotor part, which otherwise would lead to damage. In the example of the figures, the housing 31 has for this purpose an extent which increases locally from the proximal surface S1 along the axis of rotation of the rotor part R in operation, namely by moving away from the rotor part. The surface favorable to the placement of instruments is increased. In the case of the turbine/compressor casing 15, the axis of rotation of the rotor part R, consisting of a blade 19 of rotor blade 17, corresponds to the axis AX of the turbomachine 1.

In the example of FIG. 4, these instruments are anchored to the stator structure by gluing 33, or even by mechanically welded fixing 34. However, the invention is not limited to this particular arrangement and allows the use of other fastening means that the person skilled in the art could consider.

In general, the measuring instruments are divided into two categories: the wired instruments whose data they emit are conveyed by cables 36, and the non-wired instruments of the radio-transmitter type which transmit the information by Hertzian way. In the context of the use of at least one wired instrument, the invention provides for forming the housing 31 passing through the stator part, with at least one portion which forms a duct 37 for guiding the cables 36 outside the stator part S. In a non-limiting way, the duct 37 is advantageously provided to emerge at the level of a so-called distal surface, identified by S2, delimiting the stator part S opposite the proximal surface S1. By way of example, in the case of the turbine/compressor casing 15, this duct opens onto the external surface 15b, namely into the engine compartment 14, so as not to disturb the flow of the air flow in the vein primary 12.

As regards the non-wired instruments, said to be usable wirelessly, they make it possible to dispense with the formation of such a duct 37, i.e. make it possible to limit the formation of a blind housing 31. Also, these non-wired instruments generally include an antenna to be oriented towards the stator part, in other words away from the rotor part R, so as to guarantee its integrity.

Wireless sensors are particularly well suited in the case where the stator part S designates the inner shroud 29 which supports the radially inner platform 26 of the stator vanes 18. Nevertheless, the use of wired sensors can be retained by routing the cables 36 from the housing 31, provided in the inner shroud 29 to receive the abradable material, into the engine compartment 14 passing in particular within the stator vanes 18 so as not to disturb the flow of the air flow in the primary stream 12.

In this regard, the invention advantageously provides that:

- all or part of the stator vanes define within them an internal passage which extends along the stator vane, between two mouths each formed at one of the two radially inner and outer platforms 26, 27;

- the housing 31 of the inner shroud 39 comprises ducts 37 each provided to be located in the radial extension of the mouth located at the level of the radially inner platform 26; and additionally

- the turbine/compressor casing is drilled in the radial extension of the mouth located at the level of the radially outer platform 27 to ensure communication with the engine compartment 14.

With this arrangement, the routing of the cables 36 to the engine compartment 14 is made possible while isolating them from the primary flow Fp, passing successively through the ducts 37, the stator vanes 18 defining an internal passage and the holes formed in the casing 15 .

After having arranged and fixed the instruments 32, the next step of the method consists in adding the abradable material within the housing 31, thus resulting in a stator structure comprising the stator part including the housing, the measuring instruments and the block of abradable material H. In this respect, a major feature of the invention is based on the formation of the block of abradable material H by deposition and agglomeration of a powder within the housing 31. The term agglomeration designates a state of cohesion in which the all or most of the particles of the powder are joined together to form the block of abradable material.

With reference to FIG. 5A, according to a first embodiment of the abradable material H, the method according to the invention provides for filling the housing with powder by establishing a vacuum within it. For this purpose, a sheath 38 is fixed in leaktight manner on the proximal surface S1, so as to cover the housing 31. The fixing of the sheath is for example carried out by welding. This sheath 38 comprises a filling orifice 39 at the level of which the powder is admitted within the housing 31, and a vacuum orifice 41 at the level of which the sampling of the air V, initially encapsulated during the fixing of the sheath, is carried out. In order to limit the time associated with this step, the powder filling is carried out simultaneously with the creation of the vacuum. Nevertheless, the vacuum can alternatively be carried out post-filling.

It being understood that the filling and vacuum orifices 39, 41 must constitute the only possible communication channels for establishing the vacuum, a plate 42 is fixed in a leaktight manner, for example by welding, on the stator part to obstruct the conduit 37 if necessary. sample. In particular, this plate 42, preferably metallic, is provided with passages each provided with a hermetic seal, identified by 43, in order to allow the passage of the cables 36 without hindering the establishment of the vacuum.

Once the filling has been carried out, the filling and vacuum orifices 39 are then closed in a sealed manner. The 32 instruments are bathed in the powder which fills the available volume, this volume including the housing removed from the volume taken up by the instruments and cables, as well as the space defined between the housing and the sheath.

According to this first embodiment, the next step then consists in agglomerating the powder. The method provides, without limitation, two variant embodiments following filling by vacuum.

A first variant, illustrated in FIG. 5B, consists in subjecting the powder to hot isostatic or unidirectional compression, after sealing the filling and vacuum orifices 39, 41. This involves simultaneously heating the powder and exert on the sheath a pressure directed towards the housing 31, illustrated by arrows. Preferably, the rise in temperature of the powder takes place by heating the sheath 38, the heat of which is diffused in the powder. This sheath, provided with deformation capacity, deforms under the effect of the pressure applied and limits the volume defined between it and the housing. Under the effect of compression and heat, the particles are compressed together and sinter, i.e. weld together superficially. Then, the temperature and the pressure are lowered to atmospheric value to freeze the material as it is and thus form the block of abradable material H. The sheath 38 is then removed.

Also, in the case where the sheath 38 is not superimposed on the plane P1 at the end of the hot isostatic or unidirectional compression step, it is understood that the block of abradable material forms a bulge which protrudes from the surface proximal S1. In practice, it may be desirable to keep this bulge as it is or to machine it according to the rotor/stator clearance desired for assembly in the turbomachine 1.

In a second variant, the formation of the abradable material is established by hot sintering, controlling only the temperature. To this end, the method according to the invention provides for heating the powder, below an overheating or burning value, and maintaining the powder at this temperature until the sintering is effective. By way of non-limiting example, the rise in temperature of the powder takes place by heating the sheath 38, after sealing the filling and vacuum orifices. It is understood that in the absence of overpressure within the housing 31, the heating of the powder must take place over a longer time to result in the agglomeration of the powder at iso-temperature and iso-material compared to with hot isostatic or unidirectional compression.

Referring to Figure 6, according to a second embodiment of the abradable material H, the method according to the invention provides for the use of additive manufacturing. The invention provides for the preferential use of the technique of cold spraying at supersonic speed, from the English “cold-spray”, or laser sintering by powder spraying, illustrated schematically in FIG. 6. These two techniques allow to directly construct the block of abradable material H by successive stacks of layers of agglomerated powder within the housing.

Laser sintering by powder projection consists first of all in initially melting the surface of the stator part delimiting the housing, and the surface of the metal plate oriented towards the housing in the case of the use of a wired instrument, to using a laser. Simultaneously, a jet of powder is projected via a nozzle 46 onto the molten surface. The projected powder binds to the molten surface and thus forms an extra thickness of abradable material. Once this extra thickness of abradable material has been established, it becomes the new substrate on which the new layer of abradable material is formed, and so on cyclically until the housing 31 is completely filled.

With regard to cold spraying at supersonic speed, this technique consists of injecting the powder into a flow of supersonic speed gas projected by a nozzle 47. The particles impact the surface to be coated with sufficient kinetic energy to deform plastically and bond with each other. Analogously to laser sintering by projection, the first layer of abradable material produced directly on the surface of the stator part delimiting the housing, and the surface of the plate 42 if necessary, forms the substrate for the next pass.

According to one of the variants defined in this second embodiment, the method advantageously provides for installing the nozzle, and the laser in the case of laser sintering by powder spraying, on a 5-axis device so as to be able to follow the contour housing in any form.

Also, the use of an additive manufacturing process according to the second embodiment makes it possible to directly form the block of abradable material H during the filling of the housing. It is nevertheless possible to additionally subject it either to hot sintering, or to hot isostatic-unidirectional compression in accordance with the first embodiment, with a view to giving it different properties (porosity, density, etc.) and/or operate a thermal relaxation of the residual stresses accumulated during its additive manufacturing.

Whatever the embodiment of the block of abradable material H considered, it may be desirable to protect all or part of the instruments and/or the cables liable to be damaged during the manufacture of the abradable material. In practice, the instruments can be equipped when they are placed in the housing 31, namely upstream of the manufacture of the block of abradable material H, with thermal and/or confinement barriers, identified by 44, to prevent their overheating and their compression damage. In particular, these barriers form substrates allowing the passage of the laser at the level of the instruments in the case of laser sintering by powder projection.

The formation of the block of abradable material H has been described through the use of powder metallurgy and additive manufacturing techniques. The choice of the technique used depends in particular on its compatibility with the powder constituting the abradable material, and on the expected physico-chemical properties. It is understood that the invention is not limited to the embodiments presented, and allows the use of other methods as long as their implementation involves the deposit and the agglomeration of powder within the housing to form the block of abradable material.

As it is understood, this particularity of manufacture by deposition and agglomeration of powder makes it possible to imprison and protect the measuring instruments within the block of abradable material, thus allowing them to collect data in situ, as close as possible to the seat of the interactions. rotor/stator and the most dimensioning reactions.

In addition, the manufacture of the block of abradable material directly on the wall of the stator part S delimiting the housing, ensures increased mechanical anchoring and overall cohesion. In other words, the method according to the invention has the advantage of not weakening the stator structure under the operating stresses, despite the presence of the instruments 32. Concretely, the risk of air leaks, passing through the abradable material as well as at the interface between the stator part and the abradable material, is significantly reduced. The method according to the invention is therefore particularly well suited for an application on the base of the casing 15, given that this problem of leakage is all the more essential to control at the level of turbines and compressors where any leakage can lead to a burst under the pressure of the primary vein 12.

Control and regulation

The use within the turbomachine of the data collected by the measuring instruments of the stator structures formed in accordance with the method according to the invention is now explained with reference to FIG. 1. This figure illustrates a case for which the fan casing is equipped of a block of abradable material in line with the fan blades 10 and measuring instruments, but it is understood that the approach is applicable regardless of the assembly, formed of a stator structure and a screw-type rotor part. opposite, considered.

The turbomachine 1 comprises in known manner an on-board computer, identified by 48. This on-board computer 48 is provided to enter certain flight data, namely information related to the environment and to the operation of the turbomachine, and to control the engine speed. of the turbomachine. In the context of the invention, the turbomachine is equipped with a computer 49 configured to receive and process the data provided by the measuring instruments 32. The measuring instruments 32 are connected to this computer 49 located in a protected and suitable area , by Hertzian way or by the cables which are conveyed to him. Depending on the cable routing conditions, it may be desirable to place them in ventilated trunking in order to protect them, or even to leave them bare.

In practice, this computer 49 can analyze the raw information or else interact with the on-board computer 48 to correlate it with the flight data.

These analysis results are sent to the on-board computer which becomes capable of alerting the appropriate case of wear of the abradable material, which is revealed by a deviation of the analyzed response of the measuring instruments. Similarly, the on-board computer becomes capable of alerting of an undesirable rotor-stator interaction as well as the state of play in real time, according to the index measured by the measuring instruments 32. It is understood that this arrangement makes it possible to limit the maintenance steps to the exact need, namely when the system alerts the need.

Also, the analyzed data can provide rich information to simplify these maintenance steps. By way of example, piezoelectric sensors placed at regular intervals along housing 31 are each capable of recording an impulse response reflecting a rotor/stator interaction. This pulse being recorded at different times depending on the positioning of the sensors, it follows that the localization of the impacted zone of the block of abradable material is made possible by triangularization. The duration of a maintenance step can thus be significantly reduced by focusing directly on the areas identified as defective.

Generally, engine manufacturers define the abradable material used on the basis of data collected experimentally, with margins or limitations. These tests, whose conditions are partially representative of those encountered in flight (air flow, speeds, temperatures), make it possible to study certain damage mechanisms in isolation. In this respect, it is usually impossible to establish a predictive model of the behavior of the abradable material according to all the operating hazards of the turbomachine, and consequently of the rotor part opposite.

In the context of the invention, the measuring instruments 32 are placed in situ and make it possible to acquire results representative of reality. All the physical phenomena, and their couplings, can be apprehended and lead to the formulation of a phenomenological law of behavior of the block of abradable material and the rotor part opposite. In practice, such a law results from an iterative process by comparing experimental results on test benches and results of in situ analyzes by measuring instruments. This results in a rise in maturity of the technology of abradable materials applied to rotor-stator interfaces: the abradable material can be defined in an optimal way.

As a corollary, it becomes possible to identify in real time the existence of operating hazards according to the acquisition data of the measuring instruments. In this respect, the invention advantageously provides for the on-board computer 48 to be configured to automatically regulate the instantaneous flight conditions, in particular the operation of the turbomachine according to the acquisition data, and to avoid unwanted rotor-stator interaction.

Also, the temperature of the primary stream 12 can be adjusted in real time to reduce the local stresses in the block of abradable material or even to keep the rotor-stator clearance, now assessable, at its minimum allowable value. The compression ratios through the compressors 4, 6 and the useful mechanical work in the turbines 7, 8 are thereby optimized.

Claims (10)

A method of manufacturing a turbomachine stator structure, the method comprising the steps of:
a) supply of a stator part (S) delimited by a proximal surface (S1) intended to extend opposite a rotor part (R) of the turbomachine, this stator part (S) comprising a housing (31) which opens onto the proximal surface (S1);
b) fixing on the stator part (S), within the housing (31), of at least one measuring instrument (32); And
c) filling the housing (31) by deposition and agglomeration of a powder (P) to form a block of abradable material (H). Method according to claim 1, in which step b) comprises gluing (33) or a mechanically welded assembly (34) of the measuring instrument or of each measuring instrument (32) to the stator part (S) . Method according to claim 1 or 2, in which the housing (31) of the stator part (S) provided in step a) is blind, and the measuring instrument or each measuring instrument (32) can be used wirelessly . Method according to claim 1 or 2, in which the measuring instrument or at least one of the measuring instruments (32) is wired, and the housing (31) of the stator part (S) provided in step a) comprises a conduit (37) which guides the cable of the measuring instrument or of said at least one of the measuring instruments (32) outside the stator part (S). Method according to one of the preceding claims, in which step c) comprises vacuum filling of the housing (31) with the powder (P), then agglomeration of the powder (P) by sintering. Method according to one of Claims 1 to 4, in which step c) is implemented by additive manufacturing. Turbomachine assembly comprising a rotor part (R) and a stator structure which includes a stator part (S) delimited by a proximal surface (S1) extending opposite the rotor part (R), this stator part (S) being provided with a housing opening onto the proximal surface (S1),
the stator structure comprising at least one measuring instrument (32) placed in the housing (31) by being fixed on the stator part (S), and a block of abradable material (H) filling the housing (31) by trapping said least one measuring instrument, this block of abradable material (H) consisting of an agglomeration of powder (P). Aircraft turbomachine (1) comprising an assembly according to claim 7, and a computer configured to receive and process acquisition data from said at least one measuring instrument. Turbomachine according to claim 8, comprising an on-board computer (48) configured to automatically regulate the operation of the turbomachine (1) as a function of a result of processing of the acquisition data of said at least one measuring instrument by the computer. Turbomachine according to claim 8 or 9, in which the stator part is a turbine or compressor casing (15), and the rotor part is a rotating vane (17).