Variable-speed stator of an aircraft turbomachine compressor and its method of use

Abstract

A variable-pitch stator (12) of an aircraft turbomachine compressor (1), said stator (12) comprising an outer casing (2A) extending radially around the longitudinal axis (X) of the compressor (1) and externally defining an airflow channel (2C), at least one stator blade (3) extending in the channel (2C) along a radial axis (Z) and comprising a head (31) pivotally mounted in a housing (21) of the outer casing (2A), the housing (21) of the outer casing (2A) comprising an internal cylindrical surface surrounding an external cylindrical surface of the head (31) of the stator blade (3), at least one of the internal cylindrical surfaces of the housing (21) and of the external cylindrical surface of the head (31) of the stator blade (3) comprising at least one hollow portion (22) defining at least one fluidic chamber (23), the stator (12) comprising a forced fluidic supply conduit opening into the fluidic chamber (23).Figure from the summary: Figure 2.

Description

Title of the invention: Variable timing stator for an aircraft turbomachine compressor and method of using it Technical field

[0001] The present invention relates to the field of aircraft turbomachines, and more specifically relates to a variable-pitch stator for an aircraft turbomachine compressor.

[0002] In a known manner, an aircraft turbomachine extends along a longitudinal axis oriented from upstream to downstream and comprises, from upstream to downstream in the direction of gas flow, an air inlet, one or more compressors, a combustion chamber, one or more turbines and a nozzle. The compressor comprises an inner casing and an outer casing extending radially around the longitudinal axis and together delimiting an air stream, in which the air flow admitted into the air inlet circulates. The compressor comprises, from upstream to downstream, one or more stages each comprising a rotor and a stator. The rotor comprises a set of rotor blades driven in rotation in the stream in order to accelerate the air flow. The stator comprises a set of stator blades making it possible to straighten the air flow and increase its pressure.Each stator vane comprises a blade extending radially in the vein, a root mounted in a housing secured to the inner casing, and a head mounted in a housing secured to the outer casing.

[0003] A variable pitch type stator is known, in which the head of the stator blades is mounted to pivot radially about its axis in the housing in order to adapt the angle of attack of the stator blades during flight, known as the "pitch angle". The head of the stator blades is connected to a lever, typically a connecting rod, which is rotated by a hydraulic or electric transmission.

[0004] In practice, the pivoting of the head of the stator blades in the housing generates friction inducing significant forces when adjusting the pitch angle. Friction also causes wear, eventually requiring replacement of the parts, which is costly and complex.

[0005] To reduce friction, it is known to mount the blade head with clearance in the housing. However, such clearance generates air leaks from the air stream to the outside of the compressor which reduce the performance of the aircraft turbomachine. The air leaks and friction are further amplified by the high temperatures generated by the increase in pressure of the air flow in the compressor. Such temperatures can reach several hundred degrees Celsius and cause different thermal expansion between the materials of the blade head and the housing.

[0006] To minimize both air leakage and friction, one solution would be to apply an oil or grease type lubricant to the interface between the blade head and the housing. Such a lubricant would, however, evaporate under the effect of the high temperatures present and volatilize via the air leakage.

[0007] It has also been proposed to add an abradable element between the blade head and the housing. In addition to a very limited lifespan, such an abradable element has the disadvantage of generating, as it wears, a volatile powder likely to be deposited in the air stream and reduce the performance of the turbomachine.

[0008] Finally, future compressors in the industry tend to evolve towards higher compression ratios, leading to a higher temperature with increased friction and air leaks between the blade head and the housing.

[0009] The invention thus aims to reduce the friction present at the level of the head of the blades of a variable-pitch stator of an aircraft turbomachine compressor while controlling air leaks to the outside. PRESENTATION OF THE INVENTION

[0010] The invention relates to a variable-pitch stator for an aircraft turbomachine compressor extending along a longitudinal axis oriented from upstream to downstream in the direction of circulation of an air flow, said variable-pitch stator comprising: • An outer casing extending radially around the longitudinal axis and externally delimiting an air flow circulation vein, • At least one stator vane comprising a blade extending in the vein along a radial axis and a head pivotally mounted in a housing of the outer casing along the radial axis, • The outer casing housing comprising an inner cylindrical surface surrounding an outer cylindrical surface of the stator blade head.

[0011] The invention is remarkable in that at least one of the internal cylindrical surface of the housing and the external cylindrical surface of the head of the stator blade comprises at least one hollowed-out portion extending between an external projecting portion and an internal projecting portion relative to the radial axis, the hollowed-out portion extending longitudinally back so as to define at least one fluid chamber, the variable-pitch stator comprising at least one forced fluid supply duct formed in the housing of the external casing and opening into the fluid chamber, so as to reduce friction between the head of the stator blade and the housing.

[0012] By means of the invention, a pressurized fluid is conveyed between the housing and the head of the stator blade. The recessed portion allows the pressurized fluid to be confined in the fluid chamber, thus generating an air cushion between the housing and the head of the stator blade. This reduces dynamic contact between the cylindrical surface internal surface of the housing and the external cylindrical surface of the stator blade head, and therefore friction. Wear of the blade head is thus minimized, avoiding costly and complex replacement.

[0013] According to a preferred aspect, the pressurized fluid conveyed between the housing and the head of the stator blade is air, preferably taken from the outlet of the compressor, preferably cooled. This advantageously makes it possible to limit friction between the head of the stator blade and the housing at high temperatures.

[0014] According to one aspect of the invention, the internal cylindrical surface of the housing is spaced from the external cylindrical surface of the head of the stator blade by: • An outside clearance distance at the level of the outside protruding portion and • An interior clearance distance at the level of the interior protruding portion.

[0015] This advantageously makes it possible to limit friction without generating air leaks to the outside coming from the vein. Indeed, the fluid chamber supplied with pressurized air has a pressure higher than that in the vein, so that the fluid exchanges are directed from the fluid chamber towards the vein.

[0016] According to one aspect, the internal clearance distance is greater than the external clearance distance. This advantageously makes it possible to limit fluid exchanges with the exterior of the compressor and thus to reduce performance losses linked to air leaks.

[0017] According to one aspect, the fluid chamber comprises a radial thickness, defined between the internal cylindrical surface of the housing and the external cylindrical surface of the head of the stator blade, which is at least ten times greater than the internal clearance distance, and preferably at most one hundred times greater. The radial thickness of the fluid chamber respects a compatible proportion of the supply orifice(s) as well as the guide clearances of the axis with controlled leakage towards the inside of the vein. The possible leakage towards the outside of the casing will be controlled by the combination of suitable tolerances and sealing devices not described here. The application of a proportionate fluid chamber advantageously makes it possible to have a balanced and damped guide capacity leading to an effective reduction in friction between the housing and the head of the stator blade.

[0018] According to a preferred aspect, the fluidic chamber has a height along the radial axis which is greater than 50% of the height of the housing, for effective damping of friction.

[0019] According to one aspect, the forced fluid supply conduit(s) have a diameter, preferably between 0.5 mm and 2 mm. It is recognized that a forced fluid supply conduit advantageously contributes to generating and maintaining an overpressure in the fluid chamber. This advantageously makes it possible to avoid the need for a valve. According to one aspect, a non-controlled non-return system upstream of the power supply is installed, advantageously ensuring redundancy in the air supply.

[0020] According to another aspect of the invention: • said at least one hollowed-out portion is in the form of a plurality of hollowed-out portions defining a plurality of fluid chambers distributed circumferentially around the radial axis, • said at least one forced fluid supply conduit is in the form of a plurality of forced fluid supply conduits opening into each fluid chamber, preferably having a section whose proportions promote capillary flow to prevent a pressure drop in a single chamber from spreading to the other chambers.

[0021] This advantageously makes it possible to recenter the head of the stator blade in the housing and to limit friction in the presence of a force normal to the axis of the blade exerted on the blade. Indeed, the portion of the blade head moving in the available clearance of the bore generates a pressure difference between the different facing fluid chambers which reduces dynamic contact and tends to recenter the blade in its original position.Capillary-type forced fluid supply conduits advantageously make it possible, in the case of several fluid chambers, to make the pressure in each chamber independent of that in the other chambers.

[0022] According to one aspect, the stator blade head comprises a support and a ring fixed on the support, the ring comprising an external surface defining the external cylindrical surface of the stator blade head. This advantageously allows simple mounting of the ring on the stator blade head. In addition, advantageously, the ring does not require a forced fluid supply conduit.

[0023] According to another aspect, the housing comprises a frame and a ring fixed to the frame, the ring comprising an inner surface defining the inner cylindrical surface of the housing. This advantageously allows simple mounting of the stator blade head in the housing.

[0024] According to one aspect, the ring is made of a porous material comprising a plurality of interstices, at least one of which defines the forced fluid supply duct. This advantageously makes it possible to convey the air uniformly into the fluid chamber, which makes it possible to uniformly limit the friction between the head of the stator blade and the housing.

[0025] According to one aspect, the ring is made by sintering metal powder. This advantageously ensures the strength of the ring and reduces wear while ensuring porosity allowing air to be conveyed uniformly into the fluid chamber.

[0026] According to one aspect, the ring is fixed by shrink fitting. This allows simple and durable mounting of the ring in the variable-timing stator.

[0027] The invention also relates to an assembly of a variable-timing stator as presented previously and a forced fluid supply system connected to the forced fluid supply conduit of the variable-timing stator.

[0028] The invention also relates to an aircraft turbomachine compressor comprising a variable-pitch stator as presented previously.

[0029] The invention also relates to an aircraft turbomachine comprising a compressor as described above.

[0030] The invention also relates to a method of using a variable-timing stator as presented previously comprising a step of forced fluid supply of the fluid chamber. PRESENTATION OF FIGURES

[0031] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0032] [Fig.l] is a schematic representation of an aircraft turbomachine according to one embodiment of the invention.

[0033] [Fig. 2] is a schematic representation in longitudinal half-section of a part of an aircraft turbomachine compressor comprising a variable-pitch stator according to one embodiment of the invention.

[0034] [Fig. 3] is a schematic representation in longitudinal half-section of a variable-pitch stator blade head mounted in a housing provided with a ring according to a first embodiment of the invention.

[0035] [Fig.4] is a close-up schematic representation of [Fig.3].

[0036] [Fig.5] is a schematic representation of the ring of [Fig.3] comprising a circumferential hollowed-out portion.

[0037] [Fig.6] is a schematic representation of a variant of the ring of [Fig.3] comprising several hollow portions distributed angularly.

[0038] [Fig.7] is a schematic representation in longitudinal half-section of a variable-pitch stator blade head provided with a ring mounted in a housing according to a second embodiment of the invention.

[0039] [Fig.8] is a schematic representation of the ring of [Fig.7] including a circumferential recessed portion.

[0040] [Fig. 9] is a schematic representation in longitudinal half-section of a variable-pitch stator blade head mounted in a housing according to a third form of carrying out the invention.

[0041] [Fig. 10] is a schematic representation in longitudinal half-section of a variable-pitch stator blade head without a ring mounted in a housing according to a fourth embodiment of the invention.

[0042] [Fig. 11] is a schematic representation in longitudinal half-section of a ring-free variable-pitch stator blade head mounted in a housing according to a fifth embodiment of the invention.

[0043] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0044] With reference to [Fig.l], the invention relates to an aircraft turbomachine 100 extending along a longitudinal axis X oriented from upstream to downstream and comprising, from upstream to downstream in the direction of gas flow, an air inlet 111, one or more compressors 1, a combustion chamber 113, one or more turbines 114 and a nozzle 115.

[0045] With reference to [Fig. 2], the compressor 1 comprises a casing 2 comprising an inner casing 2B and an outer casing 2A extending radially around the longitudinal axis X and together delimiting an air stream 2C, in which circulates the air flow admitted into the air inlet 111. The compressor 1 comprises from upstream to downstream one or more stages 11 each comprising a rotor 13 and a stator 12. The rotor 13 comprises a set of rotor blades 14 driven in rotation in the stream 2C in order to accelerate the air flow. The stator 12 comprises a set of stator blades 3 making it possible to straighten the air flow and increase its pressure. Each stator vane 3 comprises a blade 33 extending radially in the vein 2C, a root 32 mounted in a housing secured to the inner casing 2B, and a head 31 mounted in a housing 21 secured to the outer casing 2A.

[0046] With reference to Figures 2 and 3, the stator 12 is of the variable pitch type, in which the head 31 of the stator blades 3 is mounted to pivot radially about a radial axis Z in the housing 21 of the outer casing 2A. The housing 21 of the outer casing 2A comprises an internal cylindrical surface 21A surrounding an external cylindrical surface 31E of the head 31 of the stator blade 3. This makes it possible to adapt the angle of attack of the stator blades 3 during flight, known to those skilled in the art under the term “pitch angle”. The head 31 of the stator blades 3 is preferably connected to a lever, typically a connecting rod, which is rotated by a hydraulic or electric transmission, such as a jack or an electric motor.

[0047] According to the invention, with reference to figures 3 and 4, the variable-timing stator 12 is such that : • A recessed portion 22 is formed on the inner cylindrical surface 21A of the housing 21 (see figures 3, 4, 9 and 11) and / or the outer cylindrical surface 31E of the head 31 of the stator blade 3 (see figures 7 and 10). The recessed portion 22 extends between an outer projecting portion 51 and an inner projecting portion 52 relative to the radial axis Z. The recessed portion 22 extends longitudinally set back relative to the longitudinal axis X so as to define a fluid chamber 23. • A forced fluid supply conduit 24 is formed in the housing 21 of the outer casing 2A and opens into the fluid chamber 23, so as to reduce the friction between the head 31 of the stator blade 3 and the housing 21.

[0048] According to one aspect of the invention illustrated in Figures 3 to 9, the variable-pitch stator 12 comprises a ring 4, integral with the housing 21 or the blade head 31, which defines the hollowed-out portion 22 and the inner and outer projecting portions 51, 52. The ring 4 forms an added element which is fixed to the housing 21 or the blade head 31, preferably by shrink-fitting. Alternatively, with reference to Figures 10 and 11, the hollowed-out portion 22 and the inner and outer projecting portions 51, 52 are defined by the wall of the housing 21 and / or the blade head 31 which form a single-piece element.

[0049] Thanks to the invention, a pressurized fluid, typically air, is conveyed between the housing 21 and the head 31 of the stator blade 3. The hollowed-out portion 22 makes it possible to confine the pressurized air in the fluid chamber 23, thus generating an air cushion between the housing 21 and the head 31 of the stator blade 3. This reduces the dynamic contacts between the internal cylindrical surface 21A of the housing 21 and the external cylindrical surface 31E of the head 31 of the stator blade 3, and consequently reduces friction. The wear of the blade head 31 is thus minimized, which avoids costly and complex replacement.

[0050] According to a first embodiment of the invention illustrated in Figures 3 and 4, the hollowed-out portion 22 is formed on the internal surface 4A of a ring 4 secured to the housing 21. The housing 21 comprises a frame 211 on which the ring 4 is fixed so as to extend opposite the blade head 31. As illustrated in [Fig. 4], the ring 4 comprises an internal surface 4A defining the internal cylindrical surface 21A of the housing 21 and an external surface 4B fixed to the frame 211. The forced fluid supply conduit 24 extends through the frame 211 and the ring 4 so as to open into the fluid chamber 23.

[0051] As illustrated in [Fig.4], the internal cylindrical surface 21A of the housing 21 is separated from the external cylindrical surface 31E of the head 31 of the stator blade 3 by an external clearance distance 61, at the level of the external projecting portion 51, and an internal clearance distance 62, at the level of the internal projecting portion 52. Such clearance distances 61, 62 participate with the fluid chamber 23 in limiting friction and advantageously do not generate air leaks to the outside coming from the vein 2C. Indeed, the fluid chamber 23 supplied with pressurized air has a pressure higher than that in the vein 2C, so that the fluid exchanges are directed from the fluid chamber 23 towards the vein 2C. Preferably, the internal clearance distance 62 is greater than the external clearance distance 61 to limit the fluid exchanges with the outside.

[0052] Still with reference to [Fig. 4], the fluid chamber 23 has a radial thickness L23, defined between the internal cylindrical surface 21A of the housing 21 and the external cylindrical surface 31E of the head 31 of the stator blade 3, which is preferably at least ten times greater than the internal clearance distance 62, and preferably at most one hundred times greater. According to a preferred aspect, the ring 4 extends over the entire height of the housing 21. Preferably, the hollowed-out portion 22 extends longitudinally back from the internal projecting portion 52 by at least 0.5 mm and at most 2 mm. This advantageously makes it possible to have a sufficient volume of fluid chamber 23 to ensure a reduction in friction between the housing 21 and the head 31 of the stator blade 3.

[0053] According to a preferred aspect, the forced fluid supply conduit 24 has a capillary-type diameter D24, namely between 0.5 mm and 2 mm. A small diameter advantageously contributes to generating and maintaining an overpressure in the fluid chamber 23. This advantageously makes it possible to avoid the need for a valve. According to one aspect, a non-controlled non-return system upstream of the supply is installed, advantageously making it possible to ensure redundancy in the air routing. The forced fluid supply conduit 24 is preferably supplied with air taken from the outlet of the compressor 1, at high pressure. The taken air is preferably filtered and cooled using an exchanger.

[0054] According to a first variant illustrated in [Fig.5], the hollowed-out portion 22 is unique and preferably extends circumferentially around the radial axis Z.

[0055] According to a second variant illustrated in [Fig.6], the stator 12, and in this example the ring 4, comprises several hollow portions 22 distributed circumferentially around the radial axis Z. Each hollow portion 22 defines a fluid chamber 23 and is supplied by a forced fluid supply conduit 24. The fluid chambers 23 are independent of each other.

[0056] In the presence of a force tangential to the longitudinal axis X exerted on the stator blade 3, the blade head 31 tends to move upstream or downstream relative to the housing 21, which causes a pressure drop in the fluid chambers 23 from which the head 31 of the stator blade 3 moves away, and an increase in pressure in the fluid chambers 23 to which the head 31 of the stator blade 3 approaches. The increase in pressure in the fluid chambers 23 to which the blade head 31 approaches makes it possible to form a compact air cushion limiting the friction between the blade head 31 and the housing 21. This also contributes to recentering the head 31 of the stator blade 3 in the housing 21 of the outer casing 2A.

[0057] Preferably for the two variants of figures 5 and 6, several forced fluid supply conduits 24 open into a given fluid chamber 23 to ensure a redundant and robust supply, for example tolerating a failure of one of the forced fluid supply conduits 24.

[0058] With reference to [Fig. 7], a second embodiment is shown differing from the first embodiment in that the ring 4 is mounted on the blade head 31. In this example, the blade head 31 comprises a support 311 on which the ring 4 is fixed so as to extend opposite the housing 21. Still in this example, the ring 4 comprises an external surface 4B (see [Fig. 8]) defining the external cylindrical surface 31E of the blade head 31 and an internal surface 4A (see [Fig. 8]) fixed on the support 311. The forced fluid supply conduit 24 extends through the frame 211 and the ring 4 so as to open into the fluid chamber 23. Such an embodiment has the advantage of not requiring the ring 4 to be pierced to produce the forced fluid supply conduit 24.

[0059] In the example of [Fig.8], the ring 4 comprises a single circumferential hollow portion 22. Alternatively, the ring 4 could comprise several hollow portions 22 distributed circumferentially around the radial axis Z as in [Fig.6].

[0060] With reference to [Fig. 9], a third embodiment is shown differing from the second embodiment in that the ring 4 is integral with the housing 21 and the hollowed-out portion 22 is formed directly in the wall of the blade head 31, namely the support 311. In a manner similar to the first embodiment, the housing 21 comprises a frame 211 on which the ring 4 is fixed, both traversed by the forced fluid supply conduit 24. The blade head 31 comprises a single circumferential hollowed-out portion 22 or one or more hollowed-out portions 22 distributed angularly.

[0061] According to another variant of this embodiment, the ring 4 is made of a more porous material than the material of the outer casing 2A, preferably a sintered metal powder advantageously adapted to be hooped. One or more interstices of the material of the ring 4 define the forced fluid supply conduit 24. Preferably, the porosity of the material of the ring 4 is between 10% and 30%, so as to advantageously contain the fluid in the fluid chamber 23 while allowing a sufficient supply of fluid.

[0062] With reference to [Fig. 10], a fourth embodiment is shown differing from the third embodiment in that the stator 12 is free of a ring 4. As in the example of [Fig. 9], the hollowed-out portion 22 is formed directly in the wall of the blade head 31, namely the support 311. Such an embodiment has the advantage of not requiring a ring 4 and thus of saving space and mass in the outer casing 2A.

[0063] With reference to [Fig. 11], a fifth embodiment is shown without ring 4 as in the example of [Fig. 10]. In this embodiment, the recessed portion 22 is formed directly in the wall of the housing 21, namely the frame 211. Such an embodiment has the advantage of not requiring a ring 4 and thus saving space and mass in the outer casing 2A.

[0064] The invention also relates to a method of using a variable-pitch stator 12 of an aircraft turbomachine 60, as illustrated in FIGS. 3 to 11, which comprises a step of forced fluid supply of the fluid chamber 23. The fluid is preferably in the form of high-pressure air taken from the outlet of the compressor 1. This advantageously makes it possible to form a cushion of pressurized air between the blade head 21 and the housing 21, which limits friction and minimizes air leaks from the vein 2C.

Claims

Claims

1. Variable-pitch stator (12) of a compressor (1) of an aircraft turbomachine (100) extending along a longitudinal axis (X) oriented from upstream to downstream in the direction of circulation of an air flow, said variable-pitch stator (12) comprising: • An outer casing (2A) extending radially around the longitudinal axis (X) and externally delimiting a flow path (2C) for circulation of the air flow, • At least one stator blade (3) comprising a blade (33) extending in the flow path (2C) along a radial axis (Z) and a head (31) pivotally mounted in a housing (21) of the outer casing (2A) along the radial axis (Z), • The housing (21) of the outer casing (2A) comprising an internal cylindrical surface (21A) surrounding an external cylindrical surface (31E) of the head (31) of the blade stator (3),• Said variable-pitch stator (12) being characterized in that at least one of the internal cylindrical surface (21A) of the housing (21) and the external cylindrical surface (31E) of the head (31) of the stator blade (3) comprises at least one hollow portion (22) extending between an external projecting portion (51) and an internal projecting portion (52) relative to the radial axis (Z), the hollow portion (22) extending longitudinally set back so as to define at least one fluid chamber (23), the variable-pitch stator (12) comprising at least one forced fluid supply duct (24) formed in the housing (21) of the external casing (2A) and opening into the fluid chamber (23), so as to reduce friction between the head (31) of the stator blade (3) and the housing (21).,

2. Variable-pitch stator (12) according to claim 1, in which the internal cylindrical surface (21A) of the housing (21) is spaced from the external cylindrical surface (31E) of the head (31) of the stator blade (3) by: • An external clearance distance (61) at the external projecting portion (51) and • An interior clearance distance (62) at the level of the interior protruding portion (52).

3. A variable-time stator (12) according to claim 2, wherein the inner clearance distance (62) is greater than the outer clearance distance (61).

4. Variable-pitch stator (12) according to one of claims 2 and 3, in which the fluid chamber (23) has a radial thickness (L23), defined between the internal cylindrical surface (21A) of the housing (21) and the external cylindrical surface (31E) of the head (31) of the stator blade (3), which is at least ten times greater than the internal clearance distance (62), preferably at most one hundred times greater.

5. Variable timing stator (12) according to one of claims 1 to 4, in which the forced fluid supply conduit (24) has a diameter (D24) of between 0.5 mm and 2 mm.

6. A variable-timing stator (12) according to one of claims 1 to 5, wherein the recessed portion (22) extends circumferentially around the radial axis (Z).

7. Variable-timing stator (12) according to one of claims 1 to 5, in which: • Said at least one hollow portion (22) is in the form of a plurality of hollow portions (22) defining a plurality of fluid chambers (23) distributed circumferentially around the radial axis (Z), • Said at least one forced fluid supply conduit (24) is in the form of a plurality of forced fluid supply conduits (24) opening into each fluid chamber (23).

8. Variable-pitch stator (12) according to one of claims 1 to 7, wherein the head (31) of the stator blade (3) comprises a support (311) and a ring (4) fixed on the support (311), the ring (4) comprising an external surface (4B) defining the external cylindrical surface (31E) of the head (31) of the stator blade (3).

9. A variable-timing stator (12) according to one of claims 1 to 7, wherein the housing (21) comprises a frame (211) and a ring (4) fixed thereto on the frame (211), the ring (4) comprising an internal surface (4A) defining the internal cylindrical surface (21A) of the housing.

10. A variable-timing stator (12) according to claim 9, wherein the ring (4) is made of a porous material comprising a plurality of interstices, at least one of which defines the forced fluid supply conduit (24).

11. Variable timing stator (12) according to one of claims 8 to 10, in which the ring (4) is produced by sintering metal powder.

12. Variable timing stator (12) according to one of claims 8 to 11, in which the ring (4) is fixed by shrink fitting.

13. An assembly of a variable-timing stator (12) according to one of claims 1 to 12 and a forced fluid supply system connected to the forced fluid supply conduit (24) of the variable-timing stator (12).

14. Compressor (1) of an aircraft turbomachine (100) comprising a variable-pitch stator (12) according to one of claims 1 to 12.

15. Method of using a variable-timing stator (12) according to one of claims 1 to 12 comprising a step of forced fluid supply to the fluid chamber (23).

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