Patent Application
20240229669
The present invention relates to the field of platforms for bladed wheels.
In a known manner, as shown schematically in
In a known manner, the platform is an integral part of the bladed wheel for the fan constituting the first moving wheel stage. It must ensure the following functions:
More precisely, the performance and integration requirements are manifest by good sealing of the blade close to its root retained in the disc. This sealing is directly controlled by the capacity of the platform to be associated with the blade close to its root, and to do so at all operating points. Up to a certain clearance, it can be filled by using a seal. Above a certain clearance, it is difficult to ensure sealing.
Moreover, the performance and integration requirements are also manifest by a capacity to reduce the hub ratio. The lower this ratio, the more the flow rate increases and the better the performance of the fan will be. The reduction of this hub ratio prevents the integration of a so-called “box” platform known from the prior art. Indeed, these platforms have a box which provides the necessary stiffness for the platform in order to support acceptable levels of movement and mechanical stresses. The platform is retained upstream and downstream, for example, in correspondence with shrouds and for example an upstream end of the platform can comprise a substantially radial tab which is attached by bolts (for the principle, refer for example to the teaching of document FR-2 992 676) on the disc or an intermediate part connected to the disc. Document FR-3 029 563 proposes a key for locking the box with respect to the disc. This mode of attachment is very stable but makes the platform particularly bulky, which leads to a high hub ratio.
Thus, many documents of the prior art seek to solve the problem of the conflict between optimal attachment of the platform and obtaining a low hub ratio. For example, reference can be made to document US 20140186187 which describes a platform having a refined upstream attachment, so as to maintain a low hub ratio.
However, currently, two main solutions are distinguished for attaching a platform to the disc while maintaining a low hub ratio. According to a first solution, the platform is screwed on radial extensions of the disc (as is the case for the platform described in document US 20140186187). According to another provision, the platform is retained by a plurality of hooks carried by the disc.
These known solutions are particularly restrictive. More specifically, the multiplicity of screws or hooks imposes a certain assembly kinematics often involving swivelling the platform around the axis of rotation, then axial movement in order to engage the platform in the hooks. However, this axial movement can have an impact on the clearance previously described, creating gaps that are difficult to fill with a seal.
In this context, it is necessary to provide a platform that can be attached to a disc in a simple manner, having a low hub ratio while guaranteeing sufficient clearance to the blade and enabling the sealing of the connection with the blade root to be managed.
According to a first aspect, the invention proposes a bladed wheel platform, comprising a flow passage wall extending in an axial direction and having an upstream end and a downstream end, and comprising two axial stiffeners. The platform comprises radial retention means positioned at the upstream end and the downstream end of the flow passage wall, the radial retention means being suitable for each defining a sliding connection with a corresponding shroud of the bladed wheel and in that it comprises tangential retention means suitable for defining a sliding pivot connection between the platform and a disc of the bladed wheel.
The tangential retention means can comprise a pin and a tab having a drilled hole suitable for receiving the pin, such that the assembly comprising the tab and the pin forms a sliding pivot connection.
The tab can be attached to the flow passage and the pin can be suitable for being attached to the disc of the bladed wheel.
The radial retention means comprise an upstream circumferential land and a downstream circumferential land, which are suitable for being respectively engaged in a corresponding upstream shroud and downstream shroud of the bladed wheel.
The flow passage and the stiffeners can be made of composite materials.
According to a second aspect, the invention relates to an assembly of a bladed wheel disc and a platform, wherein the disc receives the platform and has a fitting in which is attached the pin suitable for being engaged in sliding pivot connection in the tab of the platform.
The disc can receive the platform and can comprise at least one downstream shroud suitable for receiving the downstream circumferential land and at least one upstream shroud suitable for receiving the upstream circumferential land.
According to another aspect, the invention relates to a turbomachine comprising at least one assembly according to the invention.
According to another aspect, the invention relates to an aircraft comprising at least one turbomachine according to the invention.
Other features, aims and advantages of the invention will emerge from the following description, which is given purely by way of illustration and not being limiting and which should be read with reference to the attached drawings, in which:
The invention is positioned in a bladed wheel 1 of a fan. Typically, this is a low-pressure compressor fan.
The bladed wheel 1 comprises a disc 2 on which blades 4 are attached. Platforms 6 are at the interface between the blades 4 and the disc 2 in order in particular to create, by an upper face of the platform, a flow inside the flow passage between the blades close to their root which is held in the disc in a conventional socket of the disc.
As will be described, the invention relates to the platforms 6 and the disc 2, and more particularly to the connection between the platforms 6 and the disc 2.
According to a first aspect, the invention proposes a platform 6 of a bladed wheel 1.
With reference, in particular, to
In a particularly advantageous manner, the flow passage wall 8 is made of composite material. This choice of material makes it possible to have a flow passage wall 8 having optimum curvature. Indeed, the choice of a flow passage wall 8 made of composite material makes it possible to shape the flow passage 8 according to a desired surface geometry (as opposed to a sheet-metal which is more difficult to shape). Furthermore, in the case of a blade made of composite material, the flow passage wall made of composite material promotes less aggressiveness of this wall with regard to the blades in the event of significant impact on said blades.
In addition, the platform 6 comprises two axial stiffeners 10. The stiffeners 10 are positioned under the wall of the flow passage 8 in order to stiffen it. The term bottom face means that when the platform 6 is attached to a disc 2, the stiffeners 10 are located between the disc 2 and the flow passage wall 8. Hence the air flow can flow over the flow passage wall 8 without being disturbed by the stiffeners 10. In other words, the architecture of the platform 6 with a flow passage 8 stiffened by axial stiffeners 10 makes it very advantageously possible to have a mechanically resistant structure which offers an optimum surface for the flow of the air flow.
The stiffeners 10 can preferably be made of composite material.
In a particularly advantageous manner, the platform 6 comprises both radial retention means, as well as tangential retention means.
As shown, in particular, in
Typically, the platform 6 comprises both radial retention means disposed upstream 12, as well as radial retention means disposed downstream 14.
As shown in
It is specified that the term circumferential land means a circumferential rib, i.e. in the shape of a circular arc.
As can be seen in
As is shown in
It is specified that the term circumferential land means a circumferential rib, i.e. in the shape of a circular arc.
As can be seen in
The assembly by the circumferential lands, combined with the production of a flow passage wall made of composite material, make it possible to have a very low hub ratio while minimising the mass of the bladed wheel.
The platform 6 also comprises tangential retention means.
The tangential retention means are preferably suitable for defining a sliding pivot connection between the platform 6 and the disc 2 of the bladed wheel 1.
With reference to
The tab 26 is preferably attached to the flow passage wall 8 and the pin 28 is attached to the disc 2.
The tab 26 can be made of metal and be screwed to the bottom face of the flow passage wall 8.
The tab 26 has an attachment portion 26a to the flow passage wall 8 of the platform 6 and a connection portion to the disc 26b having the drilled hole 30, this portion being intended to be connected with a fitting 36. The attachment portion and the portion having the drilled hole 30 are intersecting. More precisely, with reference to
As will be detailed below, the sliding pivot connection is a particularly advantageous provision of the invention which can ensure blocking in the tangential direction while allowing movements in the axial direction. As will be explained below, this provision is particularly interesting in the case, for example, of an impact (such as by a bird) on the bladed wheel 1.
According to another aspect, the invention proposes a disc 2 for a bladed wheel 1, suitable for cooperating with a platform 6 according to the invention.
The disc 2 according to the invention has a plurality of brackets 36, each suitable for receiving a pin 28, the brackets 36 being radial protrusions. The term fitting 36 is intended to mean a metal tab or tongue extending in a radial direction and having a drilled hole 30 suitable for receiving a pin 28.
The fitting 36 has an abutment face connected with the connection portion 26b of the tab 26.
According to a first embodiment shown in
According to a second embodiment, shown in
In addition, whatever the embodiment, the pin 28 is attached to the fitting 36. It is preferably connected to the fitting by an interlocking connection, i.e. all the degrees of freedom of the pin 28 are blocked.
The pin 28 is preferably screwed to the fitting 36, as shown in
The use of a single pin 28 in sliding pivot connection, in combination with the circumferential lands, has the advantage of facilitating the assembly compared with a multi-pin system, while maintaining a robust system for absorbing mechanical forces and positioning the platform.
Moreover, in the case of a bird ingestion type shock, the system coupled by a single pin 28 in sliding pivot connection and circumferential lands releases degrees of freedom with respect to a multi-pin system and simplifies the arrangements of platforms 6, in order to avoid the risk of damage to the platform 6 during assembly and operation.
The installation of the platform 6 is therefore made easier by releasing these degrees of freedom while maintaining the main function of the pin 28 which is to absorb the centrifugal forces.
More specifically, on the one hand, the longitudinal positioning of the fitting 36, substantially at mid-length of the disc, and the longitudinal positioning of the tab 26 substantially at mid-length of the platform, reduces the risk of deformation of the platform 6 under the effect of the centrifugal forces that the platform 6 is subject to during operation.
In addition, the installation of the platform 6 according to the invention involves shorter assembly kinematics than for the platforms of the prior art, which reduces the necessary clearances, and therefore reinforces the mechanical structure of the connection between the platform 6 and the disc 2. It is specified that the necessary clearances are directly correlated to the displacement necessary during assembly and disassembly. In the case of the invention, the assembly/disassembly kinematics are reduced, the clearances are therefore reduced accordingly.
Finally, the use of a single pin 28 per platform 6 makes possible a lighter system (i.e. lighter than the multi-pin systems of the prior art), which is particularly advantageous in an aeronautical context in which weight management is an important issue.
In addition, as shown schematically in
According to another aspect, the invention relates to an assembly comprising a disc 2 for a bladed wheel 1 according to the invention and a platform 6 according to the invention, in which the disc 2 receives the platform 6.
According to another aspect, the invention relates to a turbomachine comprising at least one assembly according to the invention.
According to another aspect, the invention relates to an aircraft comprising at least one turbomachine according to the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2105184 | May 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2022/050921 | 5/13/2022 | WO |
