Cowling for an aircraft turbomachine compressor rotor

Abstract

The invention relates to a hood (40) for a compressor disc (24) (8) for an aircraft turbomachine (1), the hood comprising a body (42), intended to be fixed to a compressor disc (24) by means of fixing screws (34), the body (42) having a generally symmetrical shape of revolution about a central axis (Y) and comprising: - a radial wall, or bottom wall, the bottom wall being annular in shape and extending radially around the central axis (Y), the bottom wall having through holes for fixing screws (34); - at least one internal circumferential wall (422), extending from the bottom wall and configured to delimit, when the hood (40) is mounted on a compressor disc (24), an annular cavity intended to contain all the screw heads of the fixing screws (34);the hood (40) having a cover (44), the cover (44) being configured to be removably fixed at least to the body (42), so as to close the annular cavity formed by the body (42) when the hood (40) is mounted on a compressor disc. Figure 4.;

Description

Title of the invention: Hood for an aircraft turbomachine compressor rotor. Technical field

[0001] The present invention relates to the field of aeronautics. It relates more particularly to a cover for a compressor disc of an aircraft turbomachine, as well as to an assembly of a compressor disc and such a cover. State of the art

[0002] Turbomachinery used for aircraft propulsion includes a gas generator. The gas generator includes, in particular, from upstream to downstream with respect to the direction of gas flow, a rectifier, a low-pressure compressor, and a high-pressure compressor.

[0003] Certain components of an aircraft turbomachine operate in a hostile environment and are exposed to high temperatures. This is the case, for example, with high-pressure compressor rotors, which are rotating elements. These high temperatures induce thermal stresses that can affect the service life of these components.

[0004] To prevent excessive heating, it is known to ensure ventilation of the compressor discs by circulating an airflow near these elements. However, certain protruding elements present on the discs, such as screw heads, are likely to generate viscous heating of the ventilation air when it encounters these elements. To remedy this problem, it is known to provide a cover to protect all the screws securing a compressor disc. Such a cover is shown in [Fig. 1], which shows a perspective cross-sectional view of a cover C attached to a compressor disc D. The cover C is in the form of a hollow, annular piece, having a first wall PI and a second wall P2, each wall having a series of opposite holes T1, T2. As shown in [Fig.[l] The holes T1 in the first wall P1 allow the cover C to be attached to a compressor disc D via the disc's mounting screws V, while the holes T2 in the second wall P2 provide access to the heads of the mounting screws V and allow the passage of a screwing tool. By covering the protrusions formed by the screw heads of the disc D, the cover in [Fig. 1] drastically reduces the viscous heating mentioned above. However, its effectiveness can be further improved. Indeed, the holes T2 in the second wall P2, although not protrusions, . They still generate viscous heating when they encounter ventilation air.

[0005] The objective of the present invention is to provide a cover for a rotating turbomachine disc which makes it possible to overcome the disadvantages of the prior art, and in particular those set out above. Description of the invention

[0006] To this end, the invention relates to a cover for a compressor disc for an aircraft turbomachine, the cover comprising a body intended to be fixed to a compressor disc by means of fixing screws, the body having a generally symmetrical shape of revolution about a central axis and comprising: - a radial wall, or bottom wall, the bottom wall being annular in shape and extending radially around the central axis, the bottom wall having through holes for fixing screws; - at least one internal circumferential wall, extending from the bottom wall and configured to delimit, when the hood is mounted on a compressor disc, an annular cavity intended to contain all the screw heads of the fixing screws; the hood comprising a cover, the cover being configured to be removably fixed at least to the body, so as to close the annular cavity formed by the body when the hood is mounted on a compressor disc.

[0007] Thus, thanks to the cover that completely seals the annular cavity intended to hold the fixing screws, the hood according to the invention has an external surface free of holes. The hood according to the invention therefore has a completely smooth external surface, thereby drastically limiting the viscous heating observed on known hoods.

[0008] The hood according to the invention may include one or more of the following optional features, considered alone or according to all possible combinations.

[0009] According to one feature, the cover is a solid element and has a general annular shape with its axis coinciding with the central axis.

[0010] According to one feature, the cover is fixed to the body by shrink fitting.

[0011] According to one feature, the cover is fixed to the body by screwing.

[0012] According to one feature, the body comprises an external circumferential wall extending from the bottom wall, the bottom wall delimiting the annular cavity with the internal and external circumferential walls.

[0013] According to one feature, the cover is at least partially inserted between the inner circumferential wall and the outer circumferential wall.

[0014] The invention also relates to an assembly of a compressor disc and a hood as defined above, the hood being fixed to the disc by means of a plurality of fixing screws.

[0015] The invention also relates to an assembly of a compressor disc and a cover as defined above, the disc comprising a ferrule, the ferrule of the disc delimiting, with the bottom wall and the internal circumferential wall of the cover, the annular cavity, the cover being fixed to the disc by means of a plurality of fixing screws, the cover being fixed to the internal circumferential wall of the body on one side and to the ferrule on the other.

[0016] According to a feature of this assembly, the cover is fixed by screwing or by shrink fitting.

[0017] The invention also relates to an aircraft turbomachine, comprising at least one conforming cowl as defined above, or an assembly of a compressor disc and a cowl as defined above.

[0018] The invention also relates to an aircraft comprising at least one propulsion assembly comprising a turbomachine as defined above. Brief description of the drawings

[0019] [Fig-1] The [Fig. 1], already described, is a partial perspective view of a known compressor disc cover.

[0020] [Fig.2] Fig.2 is a schematic cross-sectional view of a turbomachine comprising a high-pressure compressor, at least one disc of which is equipped with a hood according to the invention.

[0021] [Fig.3] The [Fig.3] is a detail view of the high-pressure compressor of the turbomachine of the [Fig.2], showing a compressor disc equipped with a hood according to the invention.

[0022] [Fig.4] The [Fig.4] is a partial schematic perspective cutaway view of a compressor disc equipped with a hood according to the invention, in which the cover is screwed onto the hood body.

[0023] [Fig.5] The [Fig.5] is a view of the whole of the [Fig.4] seen in section.

[0024] [Fig.6] The [Fig.6] is a detail view of the [Fig.5].

[0025] [Fig.7] The [Fig.7] is a half view of the whole of the [Fig.4] seen from the front.

[0026] [Fig.8] Fig.8 is a detail view similar to Fig.6, showing a hood in accordance with the invention in which the cover is fixed to the body of the hood by shrink fitting.

[0027] [Fig.9] Fig.8 is a cross-sectional view similar to that of Fig.4, showing a compressor disc comprising a ferrule, the compressor being equipped with a second example of a hood according to the invention, the cover being fixed to the compressor ferrule and to the hood body by screwing.

[0028] [Fig. 10] The [Fig. 10] is a view analogous to that of the [Fig. 10], the cover being fixed to the compressor ferrule and to the hood body by shrink fitting. Detailed description

[0029] Figure 2 represents an aircraft turbomachine 1 according to the invention, in The example is a turbofan engine (shown without the normally associated nacelle). The turbomachine 1 has an air inlet 2 through which a gas flow enters the turbomachine. The gas flow is accelerated by a fan 3. Downstream of the fan 3, the gas flow is split into a primary flow entering an internal annular channel 4, or primary channel 4, and a secondary flow entering an external annular channel 5 surrounding the internal annular channel 4, or secondary channel 5. In the primary channel 4, the primary flow successively passes through an inlet straightener 6 and a gas generator.In the example, the gas generator comprises, from upstream to downstream (with respect to the direction of gas flow), a low-pressure compressor 7, a high-pressure compressor 8, a combustion chamber 9, a high-pressure turbine 10 and a low-pressure turbine 11, and a gas exhaust casing 12 to which an exhaust nozzle (not shown) is connected. The secondary flow 5 is defined in part by a fan casing 13 surrounding the fan 3 and by a nacelle surrounding the turbomachine (not shown).

[0030] Each compressor 7, 8 comprises several stages, each stage comprising a row of moving blades and a row of fixed blades. The fixed blades are attached to compressor housings, the moving blades being attached to rotating discs. The fixed blades and housings together form the stator 20 of the compressor, and the moving blades and rotating discs together form the rotor 22 of the compressor.

[0031] As can be seen in [Fig. 3], which partially shows the rotor 22 of the high-pressure compressor 8, the rotor 22 comprises annular discs 24 that rotate about the central axis X of the turbomachine and are axially separated from each other. Each disc 24 includes a radially external portion 24a for mounting blades 26, which are regularly distributed around the circumference of the corresponding disc 24. Each disc 24 further comprises a rim 24b connecting the radially external portion 24a to a radially internal balancing portion 24c. The discs 24 are connected to each other by ferrules 28. The ferrules 28 can be integrally formed with some of the discs 24 and bolted to other discs 24.

[0032] In the example of [Fig. 3], the disk 24 located in the center of the figure is without a ferrule. The disks 24 located axially upstream and downstream of the central disk 24 comprise ferrules 28 having radial flanges 30 bearing on upstream faces 24d and downstream faces 24e of the central disc 24, and fixed to the central disc 24 by means of bolts 32.

[0033] Each bolt 32 has a fixing screw 34 comprising a head 34a bearing on a flange 30. Each bolt 32 further has a nut 36 cooperating with the threaded part of the corresponding fixing screw 34, the nut 36 bearing on the opposite flange 30.

[0034] The fixing screw 34 passes through openings provided in the flanges 30 and in the disc 24.

[0035] As seen in [Fig.3], the central disc 24 is equipped with a cover 40 according to the invention, allowing to cover all the fixing screws 34.

[0036] The hood 40 of [Fig.3] is shown in more detail in figures 4 to 7.

[0037] Figures 4 to 7 schematically represent a compressor disc, such as the compressor disc 24 of [Fig.3], equipped with a hood 40 according to the invention.

[0038] As can be seen in particular in figures 4 to 7, the hood 40 comprises a body 42, intended to be fixed to a compressor disc 24 by means of fixing screws 34, and a removable cover 44.

[0039] The body 42 has a general symmetrical shape of revolution around a central axis Y coinciding with the axis of rotation of the disk 24 to which it is assembled, and coinciding with the central axis X of the turbomachine 1 in operating configuration.

[0040] In the example, the body 42 comprises a first radial wall 420, or bottom wall 420, annular in shape and extending radially around the central axis Y. The bottom wall 420 is connected to two radially spaced circumferential walls 422, 424 extending circumferentially around the central axis Y, namely an inner circumferential wall 422 and an outer circumferential wall 424. The assembly formed by the bottom wall 420 and the inner 422 and outer 424 walls defines an annular cavity 426 extending 360° around the axis Y. This annular cavity 426 is, in its operating configuration, closed by the cover 44, which is removably attached to the body 42, near the ends of the circumferential walls 422, 424 opposite the wall base 420.

[0041] The bottom wall 420 is intended to rest on a surface of the disc 24, and to be clamped against the disc 24 by means of the fixing screws 34.

[0042] As can be seen in particular in [Fig.6], which is a detail view of [Fig.5], the bottom wall 420 has a plurality of through holes 420a for the passage of the fixing screws 34. The annular cavity 426 of the body 42 has dimensions enabling it to contain all the heads 34a of the fixing screws 34 when they are in their tightening position.

[0043] As can be seen in Figures 4 to 7, the cover 44 closes the annular cavity 426 of the body 42 by presenting a smooth outer surface 440 which prevents the viscous heating observed with the known cover of [Fig. 1]. In the example, the cover 44 has a generally annular shape.

[0044] In order to allow access to the heads of the fixing screws 34 during the mounting and dismounting of the disc 24, the cover 44 is removable.

[0045] In the example shown in Figures 4 to 7, the cover 44 is screwed to the body 42 of the hood 40. For this purpose, the cover 44 has an external thread and an internal thread, which cooperate respectively with an internal thread 424b formed on the radially internal surface 424a of the external circumferential wall 424 and an external thread 422b formed on the radially external surface 422a of the internal circumferential wall 422. To facilitate screwing and unscrewing the cover 44, one or more recesses may be provided on it, so as to allow the cover 44 to be rotated with a tool cooperating with this recess or these recesses (not shown). Alternatively, as shown in [Fig. 8], the cover 44 may be fixed to the body 42 of the hood 40 by shrink fitting.This can be a cold shrink-fit, in which the cover 44 is cooled while the body 42 is at room temperature, or a hot shrink-fit, in which the body 42 is heated while the cover 44 is at room temperature. A combination of these two shrink-fit methods is also possible, with the cover 44 being cooled while the body 42 is heated. To ensure the fixing of the cover 44 by shrink fitting, a shoulder 424c is provided on the radially internal surface 424a of the external circumferential wall 424, and a shoulder 422c is provided on the radially external surface 422a of the internal circumferential wall 422. The shrink fitting allows a robust fixing of the cover 44 on the body 42, thus preventing any relative movement of the cover 44 with respect to the body in operating condition, i.e. when the hood 40 is mounted on a disk 24 of a turbomachine in operating condition.In particular, spontaneous separation of the cover 44 and the body 42 is prevented.

[0046] Advantageously, regardless of the method of fixing the cover 44, in the operating configuration it is inserted into the annular cavity 426 so that the cover 44 is flush with the ends of the circumferential walls 422, 424.

[0047] Figures 9 and 10 show an example of an embodiment of the hood according to the invention, adapted to be fixed to a compressor disc comprising a ferrule 28.

[0048] As can be seen in Figures 9 and 10, the compressor disc has a ferrule 28 allowing this disc 24 to be fixed to an adjacent compressor disc. In the example in Figures 9 and 10, the ferrule 28 is substituted for the circumferential wall. external 424 of the hood 40 of Figures 4 to 7. Thus, the annular cavity 426 is formed by the bottom wall 420 and the internal circumferential wall 422 of the hood on one side, and by the ferrule 28 of the compressor disc 24 on the other. The annular cavity 426 is, as with the hood of Figures 4 to 7, closed by the cover 44. The cover 44 is fixed both to the body 42 of the hood 40 (and more precisely to the internal circumferential wall 420) and to the ferrule 28, either by screwing ([Fig. 9]) or by shrink fitting ([Fig. 10]).

[0049] The elements of the hood 40 will preferably be made of a metallic alloy, for example a titanium-based alloy.

Claims

Demands

1. Hood (40) for compressor disc (24) (8) for aircraft turbomachine (1), the hood comprising a body (42), intended to be fixed to a compressor disc (24) by means of fixing screws (34), the body (42) having a generally symmetrical shape of revolution about a central axis (Y) and comprising: - a radial wall, or bottom wall (420), the bottom wall being annular in shape and extending radially around the central axis (Y), the bottom wall having through holes (420a) for fixing screws (34); - at least one internal circumferential wall (422), extending from the bottom wall and configured to delimit, when the hood (40) is mounted on a compressor disc (24) (8), an annular cavity (426) intended to contain all the screw heads of the fixing screws (34);the hood (40) comprising a cover (44), the cover (44) being configured to be removably fixed at least to the body (42), so as to close the annular cavity formed by the body (42) when the hood (40) is mounted on a compressor disc (8).;

2. Hood (40) according to claim 1, wherein the cover is a solid element and has a general annular shape with axis coinciding with the central axis (Y).

3. Hood (40) according to any one of the preceding claims, wherein the cover is fixed to the body (42) by shrink fitting.

4. Hood (40) according to any one of the preceding claims, wherein the cover is fixed to the body (42) by screwing.

5. Hood (40) according to any one of the preceding claims, wherein the body (42) comprises an external circumferential wall (424) extending from the bottom wall, the bottom wall (420) delimiting with the internal circumferential walls (422) and external (424) the annular cavity (426).

6. Hood (40) according to the preceding claim, in which the cover (44) is at least partially inserted between the inner circumferential wall (424) and the outer circumferential wall (424).

7. Assembly of a compressor disc (24) and a hood (40) according to any one of the preceding claims, the hood (40) being fixed to the disc by means of a plurality of fixing screws (34).

8. Assembly of a compressor disc (24) and a cover (40) according to any one of claims 1 to 4, the disc comprising a ferrule (28), the ferrule (28) of the disc (24) delimiting, with the bottom wall (42) and the internal circumferential wall (422) of the cover (40), the annular cavity (426), the cover (40) being fixed to the disc by means of a plurality of fixing screws (34), the cover (44) being fixed to the internal circumferential wall (422) of the body (42) on one side and to the ferrule (28) on the other.

9. Assembly according to the preceding claim, wherein the cover (44) is fixed by screwing or by shrink fitting.

10. Aircraft turbomachine (1), comprising at least one cowling (40) according to any one of claims 1 to 6, or an assembly of a compressor disc (24) and a cowling (40) according to any one of claims 7 to 9.

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