EP3433469A1

EP3433469A1 - Fan assembly, disk and platform

Info

Publication number: EP3433469A1
Application number: EP17716956.2A
Authority: EP
Inventors: Thomas Alain DE GAILLARD; Alexandre Bernard Marie BOISSON
Original assignee: Safran Aircraft Engines SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 2016-03-21
Filing date: 2017-03-20
Publication date: 2019-01-30
Anticipated expiration: 2037-03-20
Also published as: JP2019512639A; RU2728547C2; JP7164435B2; EP3433469B1; BR112018069179A2; RU2018136891A; RU2018136891A3; FR3048997A1; US20190055847A1; US11021973B2; CA3018448A1; FR3048997B1; CN108884720A; WO2017162975A1; CN108884720B

Abstract

The invention relates to a platform (30) to be inserted between two adjacent blades (20) of a fan (2), and comprising a flow passage wall (34), a base wall (36), and axial and radial retaining surfaces. The flow passage wall (34) defines a passage for the flow of air from the fan (2), the base wall (36) includes a main surface (36a) bearing on a fan disk (40), and the axial and radial retaining surfaces are disposed at two axial ends of the platform (30). The radial retaining surface (38), disposed at the upstream axial end of the platform (30), is offset radially in the direction in which the base wall (36) bears on the disk (40), relative to the main surface (36a) of the base wall (36).

Description

PLATFORM, DISK AND BLOWER ASSEMBLY

FIELD OF THE INVENTION

The present invention relates to the general field of aeronautical turbomachines, and more specifically to the field of blade and disk platforms of the blower of an aerospace turbine engine, an assembly comprising the platforms and the disk, and a fan comprising this assembly.

STATE OF THE PRIOR ART

In a turbomachine, the blade platforms of the blower must perform several functions. From an aerodynamic point of view, these platforms have the primary function of defining the flow vein of the air. In addition, they must also be able to withstand significant effort by deforming as little as possible and remaining attached to the disc that carries them.

In order to satisfy these different requirements, certain configurations have been proposed in which the platforms have a first part making it possible to define the air flow vein and to ensure the retention of the platform when the engine is rotating, and a second part to limit the deformations of the first part under the effects of centrifugal forces and maintain the platform in position when the engine is stopped.

In existing solutions, the platform can take the form of a box with a two-dimensional vein wall retained downstream by a drum and upstream by a ferrule, the upstream retention by the ferrule being carried out above the tooth of the fan disk (a flange of the ferrule blocking the axle axially and radially upstream).

Such upstream retention performed above the disk tooth with a ferrule has the disadvantage of imposing a high hub ratio, the hub ratio being the ratio of the radius taken between the axis of rotation and the point of the edge. attacking the dawn flush on the surface of the platform, on the radius between the axis of rotation and the point of the outermost leading edge. Moreover, this upstream retention is likely to generate over-stresses on the tooth and in the cell of the disc, at the level of the connection between the ferrule and the disc.

In order to optimize the performance of the blower, and more generally of the turbomachine, it is desirable to have an assembly of an attached blower blade platform on a blower disc which has the lowest hub ratio. possible, while limiting the constraints at the level of the tooth and the cell of the disc.

PRESENTATION OF THE INVENTION

One embodiment relates to a platform adapted to be interposed between two adjacent blades of a fan, and comprising:

- A vein wall to define a fan air flow vein,

- A bottom wall with a main surface to bear on a fan disk; and

- Axial and radial retention surfaces disposed on two axial ends of the platform, characterized in that the radial retention surface disposed on the upstream axial end of the platform is offset radially, in the bearing direction of the wall of the bottom on the disc, with respect to a main surface of the bottom wall.

By "axial" is understood in the direction of the greater length of the platform, and "radial", one understands the direction perpendicular to the axial direction and the main surface of the bottom wall.

By "upstream", it comprises upstream relative to the direction of flow of air, when the platform is supported on a fan disk.

The platform can take the form of a box formed by the assembly of the vein wall and the bottom wall. The vein wall defines the flow vein of the air entering the blower. The bottom wall makes it possible to maintain the vein wall in position and also to limit its deformations under the effect of centrifugal forces. The bottom wall also has a main surface that can bear on a fan disk.

The axial and radial retention surfaces, arranged on two axial ends of the platform, allow to retain and maintain in position the platform relative to the disk on which it is supported, when the disk is moving.

The radial retention surface disposed on the upstream axial end of the platform is offset radially with respect to a main surface of the bottom wall. By "radially offset" is understood shifted in the direction of support of the bottom wall on the disk. The radial retention surface and the main surface of the bottom wall may be substantially parallel to one another. This offset of the radial retention surface makes it possible to modify the shape of the upstream axial end of the vein wall, and therefore of the platform, with respect to known platforms. For example, the platform may take the form of a plunger, that is to say whose upstream axial end is offset radially relative to the main surface of the bottom wall. This modification of the shape of the platform thus makes it possible to modify the air flow duct when the platform is placed in a blower, is therefore to reduce the hub ratio in order to improve the performance of the blower, and therefore of the turbine engine in which the fan is mounted.

In some embodiments, the bottom wall has a surface inclined with respect to the main surface of the bottom wall, continuously connecting the main surface of the bottom wall and the radial retention surface disposed on the axial end. upstream of the platform.

The radial retention surface disposed on the upstream axial end of the platform being radially offset relative to the main surface of the bottom wall, the inclined surface corresponds to the area of the bottom wall to compensate for the offset between the surface. radial retention and the main surface of the bottom wall. It is therefore understood that the inclined surface bears on the disk. The radial retention surface disposed on the upstream axial end of the platform, the inclined surface and the main surface of the bottom wall, can be in one piece constituting the bottom wall.

The presence of this inclined surface makes it possible to modify the shape of the platform and to optimize it in order to reduce the hub ratio, thereby improving the performance of the fan and the turbomachine. In some embodiments, the inclined surface is a straight wall portion.

Therefore, the straight wall portion linearly connects the radial retention surface with the main surface of the bottom wall, thereby changing the shape of the upstream axial end of the platform to decrease the hub ratio. This rectilinear wall portion has the advantage of having a simple shape and easy to achieve, for example by machining.

In some embodiments, the inclined surface is a curvilinear wall portion.

Therefore, the curvilinear wall portion progressively connects the radial retention surface with the main surface of the bottom wall, thereby changing the shape of the upstream axial end of the platform to decrease the hub ratio. This portion of curvilinear wall has the advantage of softening the change of slope from the main surface of the bottom wall, avoiding the presence of a break at the junction between the inclined surface and the main surface, unlike the rectilinear wall portion, and thus reduce the stresses at this junction.

In some embodiments, the inclined surface and the vein wall are substantially parallel.

Therefore, the upstream axial end of the platform has a plunging shape, the inclined surface and the vein portion being inclined radially in the same way in the support direction of the platform on the disc. This shape of the upstream axial end of the platform makes it possible to reduce the hub ratio.

The present disclosure also relates to a disc adapted to support platforms and vanes of a blower, and comprising:

an outer surface having a succession of grooves for receiving the fan blades and teeth interposed between the grooves to support the fan platforms,

an upstream face of the disk, and

a plurality of axial projections disposed radially around the axis of the disk on the upstream face of the disk, and capable of being fixed to a fan platform retention flange, characterized in that the projections are shifted radially inwardly of the disc relative to the teeth of the disc.

By "upstream face", one understands upstream with respect to the direction of flow of the air, when the disc is arranged in a blower.

By "axial projections" is understood axial in the direction of flow of the air, when the disc is disposed in a blower.

By "radially offset" is understood shifted inwardly of the disk, that is to say towards the axis of rotation of the disk.

The disk can have as many axial projections as teeth. The axial projections may each have an orifice allowing the axial projections to be attached to a fan platform retention flange, for example using a screw or bolt.

The axial projections being offset radially inwardly of the disk relative to the teeth of the disk, when the projections are fixed on a platform retaining flange, the fixing area on the projections is thus offset radially relative to the teeth of the plate. disk. This has the advantage of limiting the stresses at the tooth of the disk, when an external element, for example a platform retention flange, is fixed on the disk.

Moreover, this fixing zone being radially offset relative to the teeth of the disc, this has the advantage of freeing space at the upstream axial end of the disc tooth, allowing for example to machine the tooth of the disc.

In some embodiments, the axial projections are studs machined on the upstream face of the disk.

They may have a cubic shape, and each comprise a fixing orifice machined axially on an upstream face of the projections. The fixing holes may be used to fix an element external to the disk, for example a retention flange or a ferrule, by means of a screw or a bolt, for example. The axial projections may also include an insertion port machined radially on an outer face of the projections. The insertion holes can be used to insert fasteners, through which an outer member can be attached to the disc.

In some embodiments, an upstream axial end of the disc teeth has a beveled surface. The bevelled surface may be in the form of an inclined surface, with respect to a major surface of the disc tooth, towards the interior of the disc. The bevelled surface can be made by machining the upstream axial end of the disc tooth, for example. This machining is possible thanks to the space released by the radial offset of the axial projections on the upstream face of the disc. The presence of this beveled surface has the advantage of being able to adapt the shape of the disc tooth to the shape of a platform coming to bear on the tooth, and thus to reduce the hub ratio to improve the performance of the blower.

The present disclosure also relates to an assembly comprising a disk and at least one platform, and further comprising at least one upstream retention flange to ensure the axial and radial retention of the upstream axial end of the platform, in which the retention flange upstream is fixed on a projection of the upstream face of the disk.

When the retention flange is attached to the disc, the interface between the flange and the disc, corresponding to the area of attachment of the flange to an axial projection of the disc, is radially offset towards the inside of the disc, relative to the tooth of the disc, compared to known systems in which this interface is located at the tooth of the disc. This offset makes it possible to limit the stresses at the upstream axial end of the teeth and the grooves of the disc. In addition, the offset of this interface makes it possible to free up space at the upstream axial end of the tooth of the disc, offering more possibility of machining the tooth and thus of modifying the shape of the platform and thus, the reduction of the hub ratio.

In some embodiments, when the platform is supported on a tooth of the disk, the inclined surface of the bottom wall is in contact with the beveled surface of the tooth of the disk and the inclined surface and the beveled surface are parallel.

The interface between the retention flange and the disc being shifted inwardly of the disc, the disc tooth can be more freely machined. Thus, the upstream axial end of the tooth may have a beveling to adapt to the shape of the platform, the beveled surface being parallel to the inclined surface of the platform. This has the advantage of creating a compact assembly, in which the The platform is held against the tooth of the disc by the retention flange fixed at a protrusion of the disc.

In some embodiments, the upstream retention flange is a ferrule.

The present disclosure also relates to a turbomachine blower comprising an assembly according to any one of the embodiments described herein, and a plurality of vanes mounted in the grooves of the disc.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its advantages will be better understood on reading the detailed description given below of various embodiments of the invention given as non-limiting examples. This description refers to the pages of annexed figures, in which:

FIG. 1 is a schematic sectional view of a turbomachine according to the invention,

FIG. 2 is a schematic view along direction II of the fan of FIG. 1,

FIGS. 3A and 3B are views in longitudinal section of a platform according to the invention,

FIG. 4 is a perspective view of a disk according to the invention,

Figure 5 is a longitudinal sectional view of an assembly comprising a retention flange, a platform and a disc according to the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In this presentation, the term "longitudinal" and its derivatives are defined in relation to the principal direction of the platform in question; the terms "radial", "interior", "exterior" and their derivatives are themselves defined with respect to the main axis of the turbomachine; finally, the terms "upstream" and "downstream" are defined with respect to the flow direction of the fluid passing through the turbomachine. Also, unless otherwise indicated, the same reference characters in different figures denote the same characteristics.

Figure 1 shows a schematic longitudinal sectional view of a turbofan engine 1 centered on the axis A according to the invention. It comprises, from upstream to downstream: a fan 2, a low compressor pressure 3, a high pressure compressor 4, a combustion chamber 5, a high pressure turbine 6, and a low pressure turbine 7.

FIG. 2 shows a schematic view of the fan 2 of FIG. 1 along the direction II. The fan 2 comprises a fan disk 40 in which a plurality of grooves 42 are formed at its outer periphery. These grooves 42 are rectilinear and extend axially from upstream to downstream all along the disc 40. They are also regularly distributed around the axis A of the disc 40. In this way, each groove 42 defines with its neighbor a tooth 44 which also extends axially from upstream to downstream along the disc 40. Equivalently, a groove 42 is delimited between two adjacent teeth 44.

The fan 2 further comprises a plurality of blades 20 of curvilinear profile (only four blades 20 have been shown in Figure 2). Each blade 20 has a foot 20a which is mounted in a respective groove 42 of the fan disk 40. For this purpose, the root 20a of a blade 20 may have a fir or dovetail shape adapted to the geometry of the blades. grooves 42.

Finally, the fan 2 comprises a plurality of reported platforms 30, each platform 30 being mounted in the gap between two adjacent fan blades 20, in the vicinity of the feet 20a thereof, in order to delimit, on the inside, a vein annular air inlet into the blower 2, the vein being delimited on the outer side by a fan casing.

Figures 1 and 2 also show an inner radius RI and an outer radius RE. The internal radius R1 corresponds to the radius between the axis of rotation A and the point of the leading edge of a blade 20 flush with the surface of a platform 30. The outer radius RE corresponds to the radius taken between the rotation axis A and the point of the leading edge of an outermost blade 20. These two radii RI, RE are those used in the calculation of the hub ratio RI / RE that the assembly according to the invention proposes to decrease (in particular reducing the internal radius RI). In other words, the reduction of the hub ratio, in particular by acting on the internal radius RI, amounts to bringing the aerodynamic stream of air intake closer to the fan disk. FIGS. 3A and 3B show views in longitudinal section of the platform 30. The platform 30, object of the present invention, comprises a vein wall 34, a bottom wall 36, and radial and axial retention surfaces 38 and 39 disposed at the two axial ends of the platform 30. The assembly formed by the vein wall 34 and the wall of 36, forms a box 32, forming the platform 30. The bottom wall consists of a main surface 36a and a inclined surface 36b. The inclined surface 36b continuously connects the main surface 36a and the retention surface 38, so that the retention surface 38, located at the upstream axial end of the platform, is radially offset from the main surface 36a. In the example of FIG. 3A, the inclined surface 36b is a rectilinear wall portion. In the example of Figure 3B, the inclined surface 36b is a curvilinear wall portion.

Figure 4 shows a perspective view of a fan disk having an outer surface 40a and an upstream face 40b. The outer surface 40a has a succession of grooves 42 in which can be housed a foot 20a blade 20 blower, and teeth 44 interposed between the grooves 42, capable of supporting the platforms 30 of blower. Each tooth 44 may have a main tooth surface 44a, and a bevelled surface 44b. The beveled surface 44b is made, for example by machining the upstream axial end of the tooth 44, so that the shape of the bevelled surface 44b is identical to the shape of the inclined surface 36b of the platform 30. Therefore when a platform 30 bears on a tooth 44, the main surface 36a of the platform is in contact with the main surface of the tooth 44a, and the inclined surface 36b of the platform is in contact with the bevelled surface 44b of the tooth, as shown in Figure 5.

Furthermore, the disk 40 comprises, on its upstream face 40b, a plurality of axial projections 46, which may have a cubic shape and be arranged circumferentially, at regular intervals, about the axis A. The number of axial projections 46 may be equal to the number of teeth 44, each projection 46 being aligned radially with the corresponding tooth 44. In addition, each axial projection 46 is offset radially inwardly of the disk, that is to say towards the axis A, relative to the corresponding tooth 44. For example, a distance between the axis A and a face outer 46a of a projection 46 may be smaller than the distance between the axis A and a groove 42.

Each axial projection 46 may comprise a fixing orifice 460b on its upstream face 46b, for inserting a fixing means 49, for example a screw or a bolt. Each axial projection 46 may also include an insertion hole 460a on its outer face 46a, for inserting a fastener 47, for example an insert, having a threaded hole. The fixing of an upstream retention flange 50, for example a ferrule, can thus be carried out at an axial projection 46, for example by inserting the fixing means 49 through a flange orifice 52 and the orifice 460b fixing the projection, the fixing element 49 then being fixed, for example screwed, to the fastening element 47 inserted by the insertion hole 460a of the projection. The retention flange 50 being fixed to the disc 40, an upper surface 54 of the flange 50 then makes it possible to ensure the radial retention of the platform 30.

The zone of attachment between the disc 40 and the retention flange 50 being situated at the level of the axial projections 46, this makes it possible to limit the stresses exerted during the operation of the blower at the level of sensitive surfaces such as the upstream axial end of the teeth. 44 and grooves 42 of the disk. Moreover, this interface between the disk 40 and the retention flange 50 being offset radially with respect to the teeth of the disk, in comparison with the known structures, this makes it possible to free up space at the upstream axial end of the teeth of the disk. disk. It is therefore possible to modify more freely the upstream axial end of the teeth 44, and therefore the upstream axial end of the platform 30, and thus, to reduce the hub ratio in order to optimize the performance of the fan, and therefore the turbine engine in which is mounted the fan. FIG. 5 illustrates, for example, a platform 30 whose box 32 has a plunging shape towards the inside of the disc 40, thanks to the beveled surface 44b of the disc 40 and to the inclined surface 36b of the platform 30.

Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual characteristics of various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Platform (30) adapted to be interposed between two adjacent blades (20) of a fan (2), and comprising:

a vein wall (34) for defining a fan air flow vein (2),

- a bottom wall (36) with a main surface (36a) for resting on a disk (40) blower;

the platform (30) having axial and radial retention surfaces disposed on two axial ends of the platform (30), the radial retention surface (38) disposed on the upstream axial end of the platform (30) being radially offset, in the bearing direction of the bottom wall (36) on the disk (40), with respect to the main surface (36a) of the bottom wall (36), characterized in that the bottom wall (36) has an inclined surface (36b) with respect to the main surface (36a) of the bottom wall (36), continuously connecting the main surface (36a) of the bottom wall (36) and the radial retention surface ( 38) disposed on the upstream axial end of the platform (30).

The platform (30) of claim 1 wherein the inclined surface (36b) is a straight wall portion.

The platform (30) of claim 1 wherein the inclined surface (36b) is a curvilinear wall portion.

The platform (30) according to any one of claims 1 to 3 wherein the inclined surface (36b) and the vein wall (34) are substantially parallel.

Disc (40) adapted to support platforms (30) and vanes (20) of a blower (2), and comprising:

an outer surface (40a) having a succession of grooves (42) for receiving the fan blades (20) and teeth (44) interposed between the grooves (42) for supporting the fan platforms (30)

an upstream face (40b) of the disk, and

a plurality of axial projections (46) arranged radially about the axis A of the disk on the upstream face (40b) of the disk (40), and adapted to be fixed to a fan platform retaining flange (50), the projections (46) being radially inwardly disc (40) relative to the teeth (44) of the disc (40), characterized in that an upstream axial end of the teeth (44) of the disc has a bevelled surface (44b).

6. Disk (40) according to claim 5, wherein the axial projections (46) are studs machined on the upstream face (40b) of the disk.

An assembly comprising at least one platform (30) according to any one of claims 1 to 4, and a disc (40) according to claim 5 or 6, and further comprising at least one upstream retention flange (50) for providing axial and radial retention of the upstream axial end of the platform (30), wherein the upstream retention flange (50) is fixed on an axial projection (46) of the upstream face (40b) of the disc (40) .

8. The assembly of claim 7, wherein, when the platform (30) bears on a tooth (44) of the disk (40), the inclined surface (36b) of the bottom wall (36) is in contact with the beveled surface (44b) of the disk tooth (44) and the inclined surface (36b) and the bevelled surface (44b) are parallel.

The assembly of claim 7 or 8, wherein the upstream retention flange (50) is a ferrule.

10. A turbomachine blower (2) comprising an assembly according to any one of claims 7 to 9, and a plurality of vanes (20) mounted in the grooves (42) of the disk (40).