Cowling for an aircraft turbomachine compressor rotor

Abstract

The invention relates to a cover (40) for a turbomachine compressor disc (24), comprising a body (42) having a symmetrical shape about a central axis (Y) and comprising: - a bottom wall, the bottom wall being annular in shape and extending radially around the central axis (Y), and having through holes for screws (34); - at least one internal wall (422), extending from the bottom wall and defining an annular cavity for containing all the screw heads of the screws (34); - a closing wall (428) closing the annular cavity formed by the body (42), the closing wall (428) having a screw hole (428a) opposite each through hole in the bottom wall for the passage of a screwing tool; the cover (40) having plugs (44) obstructing the screw holes (428a). 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 first radial wall, or bottom wall, the bottom wall being annular in shape and extending radially around the central axis, the bottom wall having 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; - a closing wall intended to close the annular cavity formed by the body when the hood is mounted on a compressor disc, the closing wall having a screw hole opposite each through hole in the bottom wall for the passage of a screwing tool; the hood having, in operating configuration, plugs obstructing the screw holes of the closing wall.

[0007] Thus, by providing a closing wall in which each screw hole is plugged, the hood according to the invention has an external surface free of holes. The hood according to the invention therefore has a predominantly 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, each plug is configured to be inserted at least partially into the respective screw hole.

[0010] According to one feature, each plug is flush with the external surface of the closing wall.

[0011] According to one feature, each plug is fixed to the body by shrink fitting.

[0012] According to one feature, each cap is fixed to the body by screwing.

[0013] 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.

[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, each screw hole in the closing wall being blocked by a respective plug.

[0015] The invention also relates to an assembly of a compressor disc and a hood 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 hood, the annular cavity, the hood being fixed to the disc by means of a plurality of fixing screws, each screw hole of the closing wall being obstructed by a respective plug.

[0016] The invention also relates to an aircraft turbomachine, comprising at least one cowling conforming to that defined above, or an assembly of a compressor disc and a cowling conforming to that defined above.

[0017] The invention also relates to an aircraft turbomachine, comprising at least one compressor disc equipped with a hood 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 cover conforming 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 view cut off from a compressor disc equipped with a cover according to the invention.

[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 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.

[0027] [Fig.9] The [Fig.9] is a detail view of the [Fig.8]. Detailed description

[0028] Figure 2 represents an aircraft turbomachine 1 according to the invention, in this example 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).

[0029] Each compressor 7, 8 comprises several stages, each stage having a row of moving blades and a row of fixed blades. The fixed blades are fixed to compressor housings, the moving blades being fixed 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.

[0030] 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 includes 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.

[0031] In the example of [Fig. 3], the disc 24 located in the center of the figure is without a ferrule. The discs 24 located axially upstream and downstream of the central disc 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.

[0032] 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.

[0033] The fixing screws 34 pass through openings provided in the flanges 30 and in the disc 24.

[0034] 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.

[0035] The hood 40 of [Fig.3] is shown in more detail in figures 4 to 7.

[0036] 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.

[0037] As can be seen in particular in figures 4 to 7, the hood 40 has a body 42, intended to be fixed to a compressor disc 24 by means of fixing screws 34.

[0038] 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.

[0039] 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 closed in the example by a second radial wall 428, or closing wall 428, connected to the two circumferential walls 422, 424. The closing wall 428 is annular in shape and extends radially around the central Y axis.

[0040] 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.

[0041] 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.

[0042] As shown in Figures 4 to 7, the closing wall 428 has openings 428a, or screw holes 428a, allowing access to the heads 34a of the fixing screws 34 during the assembly and disassembly of the cover 40. The screw holes 428a allow an operator, when tightening or loosening the fastening screws, to successively insert a fastening screw 34 and / or the end of a suitable screw-driving tool into each screw hole 428a. Each screw hole 428a has a diameter that allows the passage of a fastening screw 34, as well as the passage of a screw-driving tool.

[0043] According to the invention, the cover 40 has, for each screw hole 428a, a plug 44 for blocking the corresponding screw hole. Thus, when all the fixing screws 34 have been correctly installed and tightened, each screw hole is blocked by a respective plug 44. The closing wall 428, equipped with the plugs 44, therefore closes the annular cavity 426 of the body 42, presenting the smoothest possible outer surface, thus preventing the viscous heating observed with the cover known in [Fig. 1]. The plugs 44 are preferably removable, so that they can be taken off when it is necessary to access the fixing screws 34 later, for example, to remove the disc 24.

[0044] In the example shown in the figures, each plug 44 is shrink-fitted onto the body 42. This can be a cold shrink-fit, in which the plug 44 is cooled while the body 42 is at ambient temperature, or a hot shrink-fit, in which the body 42 is heated while the plug 44 is at ambient temperature. A combination of these two types of shrink-fitting can also be considered, with the plug 44 being cooled while the body 42 is heated. Shrink-fitting provides a robust attachment of the plugs 44 to the body 42, thus preventing any relative movement of a plug 44 with respect to the body under operating conditions, i.e., when the cowl 40 is mounted on a disk 24 of a turbomachine in operation. In particular, any spontaneous removal of a plug is prevented.

[0045] In the example shown in the figures, and as can be seen in particular in [Fig. 6], the plugs 44 are fixed to the body 42 by being at least partially inserted into the corresponding screw hole 428a. Preferably, each plug 44 is flush with the outer surface of the closing wall 128. Thus, the cover 40 has a completely smooth outer surface.

[0046] In an embodiment not shown, each plug 44 is fixed to the body 42 by screwing. For this purpose, each screw hole is a tapped hole, preferably with a thread whose direction is opposite to the direction of rotation of the compressor disc. To facilitate screwing and unscrewing the plugs 44, each plug 44 may have a recess allowing the plug 44 to be rotated by means of a tool.

[0047] Figures 8 and 9 show an example of an embodiment of the hood according to the invention, when adapted to be fixed to a compressor disc having a ferrule.

[0048] As shown in Figures 8 and 9, the compressor disc 24 has a ferrule 28 for attaching it to an adjacent compressor disc. In the example shown in Figures 8 and 9, the ferrule 28 replaces the outer circumferential wall 424 of the cover 40 in Figures 4 to 7. Thus, the annular cavity 426 is formed by the bottom wall 420 and the inner circumferential wall 422 of the cover on the one hand, and by the ferrule 28 of the compressor disc 24 on the other. The annular cavity 426 is, as with the cover in Figures 4 to 7, closed by the closing wall 428 fitted with plugs 44. The free end of the closing wall 428 rests against the ferrule 28 in this example.

[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 first radial wall, or bottom wall (420), the bottom wall (420) being annular in shape and extending radially around the central axis (Y), the bottom wall (420) 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);- a closing wall (428) intended to close the annular cavity (426) formed by the body (42) when the hood (40) is mounted on a compressor disc (8), the closing wall (428) having a screw hole (428a) opposite each through hole (420a) in the bottom wall (420) for the passage of a screwing tool; the hood (40) having, in operating configuration, plugs (44) obstructing the screw holes (428a) in the closing wall (428).

2. Hood (40) according to claim 1, wherein each plug (44) is configured to be inserted at least partially into the respective screw hole (428a).

3. Hood (40) according to the preceding claim, wherein each plug (44) is flush with the external surface of the closing wall (428a).

4. Hood (40) according to any one of the preceding claims, wherein each cap (44) is fixed to the body (42) by shrink fitting.

5. Hood (40) according to any one of claims 1 to 3, wherein each cap (44) is fixed to the body (42) by screwing.

6. Hood (40) according to claim 1, wherein the body (42) comprises an external circumferential wall (424) extending from the bottom wall (420), the bottom wall (420) delimiting with the internal (422) and external (424) circumferential walls the annular cavity (426).

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), each screw hole in the closing wall being blocked by a respective plug.

8. Assembly of a compressor disc (24) and a hood (40) according to any one of claims 1 to 5, 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 hood (40), the annular cavity (426), the hood (40) being fixed to the disc by means of a plurality of fixing screws (34), each screw hole of the closing wall being blocked by a respective plug.

9. 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 and 8.

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