Turbmachine fan disc

Abstract

A disc able to support platforms and blades of a fan, and including an external 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 disc, and a plurality of radial protrusions disposed radially around the axis of the disc on the upstream face of the disc, and able to be fastened to a fan platform retaining flange, the protrusions being offset radially toward the interior of the disc relative to the grooves of the disc, and being disposed circumferentially between two teeth of the disc.

Claims

1. A disc configured to support platforms and blades of a fan, and including: an external 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 disc, an annular axial protrusion disposed radially around an axis of the disc on the upstream face of the disc, and a plurality of radial protrusions disposed radially around the axis and extending from an upstream face of the annular axial protrusion towards the center of the disc, and configured to be fastened to a fan platform retaining flange, the protrusions being offset radially toward the interior of the disc relative to the grooves of the disc, and being disposed circumferentially between two successive teeth of the disc, the number of radial protrusions being equal to half the number of grooves of the disc.

2. The disc according to claim 1, wherein the radial protrusions are tabs machined on the upstream face of the disc and folded toward the center of the disc.

3. The disc according to claim 1, wherein each respective face of a respective radial protrusion includes a respective opening with an axis parallel to the axis of the disc.

4. The disc according to claim 3, wherein, in an upstream side view of the disc along the axis of the disc, the center of the opening of each radial protrusion is disposed on a straight line passing through the center of the disc and the bottom of a groove of the disc, the bottom of a groove being the point in the groove, in this view, situated at equal distance from the two teeth between which the groove is located.

5. The disc according to claim 4, wherein, a radius of the disc being a segment between the center of the disc and the bottom of a groove, a distance between the center of the disc and the center of the opening of the radial protrusion is less than 95% of the radius of the disc.

6. The disc according to claim 1, wherein the radial protrusions are disposed on the upstream face of the disc at regular intervals along the circumference of the disc.

7. An assembly comprising the disc according to claim 1, at least one of the platforms, and at least one upstream retaining flange to ensure the axial and radial retention of an upstream axial end of the at least one of the platforms, wherein the at least one upstream retaining flange is fastened to the radial protrusions of the upstream face of the disc.

8. The assembly according to claim 7, wherein the at least one upstream retaining flange is a shroud fastened to each radial protrusion by means of a bolt.

9. A turbomachine fan comprising the assembly according to claim 7, and a plurality of the blades mounted in the grooves of the disc.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its advantages will be better understood upon reading the detailed description made hereafter of different embodiments of the invention, given by way of non-limiting examples. This description refers to the appended pages of figures, in which:

(2) FIG. 1 is a schematic section view of a turbomachine according to the invention,

(3) FIG. 2 is a schematic view in the direction II of the fan of FIG. 1,

(4) FIG. 3 is a perspective view of a disc according to the invention,

(5) FIG. 4 is a longitudinal section view of an assembly comprising a retaining flange, a platform and a disc according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) In the present disclosure, the term “longitudinal” and its derivatives are defined relative to the principal direction of the platform considered; the terms “radial,” “interior” and their derivatives are, for their part, defined relative to the axis of the disc, corresponding to the principal axis of the turbomachine; finally, the terms “upstream” and “downstream” are defined relative to the flow direction of the fluid passing through the turbomachine. Thus, unless otherwise indicated, the same reference symbols designate the same features on different figures.

(7) FIG. 1 shows a schematic view in longitudinal section of a double flow turbojet 1 centered on the axis A according to the invention. It comprises, from upstream to downstream: a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, and a low-pressure turbine 7.

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

(9) The fan 2 also comprises a plurality of blades 20 with a curvilinear profile (only four blades 20 are shown in FIG. 2). Each blade 20 has a root 20a which is mounted in a respective groove 42 of the fan disc 40. To this end, the root 20a of a blade 20 can have a pine tree or a dovetail shape suited to the geometry of the grooves 42.

(10) Finally, the fan 2 comprises a plurality of applied platforms 30, each platform 30 being mounted in the interval between two adjacent fan blades 20, in proximity to their roots 20a, in order to delimit, on the interior side, an annular air entry stream in the fan 2, the stream being delimited on the exterior side by a fan casing.

(11) FIGS. 1 and 2 also show an inner radius RI and an outer radius RE. The inner radius RI corresponds to the radius taken between the axis of rotation and the point in the leading edge of a blade 20 flush with the surface of a platform 30. The external radius RE corresponds, for its part, to the radius taken between the axis of rotation A and the outermost point of the leading edge of a blade 20. These two radii RI, RE, are those used in calculating the hub ratio RI/RE. The fact of reducing the inner radius RI allows reducing this hub ratio. In other words, the reduction of the hub ratio, by acting in particular on the inner radius RI, amounts to causing the aerodynamic air entry stream to approach the fan disc as closely as possible.

(12) FIG. 3 shows a perspective view of a fan disc comprising an external surface 40a and an upstream face 40b. The outer surface 40a has a succession of grooves 42 in which a root 20a of a fan blade 20 can be accommodated, and teeth 44 interposed between the grooves 42, which can support the fan platforms 30. Each tooth 44 can include a main tooth surface 44a, and a tapered surface 44b at its upstream axial end.

(13) Moreover, the disc 40 comprises, on its upstream face 40b, a plurality of radial protrusions 46, having the shape of tongues, and being disposed circumferentially at regular intervals around the axis A. These protrusions can be made for example by machining the upstream face 40b of the disc, for example on the disc stem. The number of radial protrusions 46 can be equal to half the number of grooves 42, each protrusion 46 being aligned radially with the corresponding groove 42. In other words, each protrusion 46 is interposed circumferentially between two teeth 44 of the disc 40. Moreover, each radial protrusion 46 is radially offset toward the interior of the disc, i.e. toward the axis A, relative to the corresponding groove 42.

(14) Each radial protrusion 46 can include a fastening opening 46a on its upstream face 46b, allowing inserting a fastening means 49, for example a screw or a bolt. The attachment of an upstream retaining flange 50, a shroud for example, can thus be carried out at a radial protrusion 46, for example by inserting the fastening means 49 through a flange opening 52 and the fastening opening 46a of the protrusion, the fastening means 49 then being fastened, for example by a bolt, to the radial protrusion 46. The retaining flange 50 being fastened to the disc 40, an upper surface 54 of the flange 50 then allows ensuring the radial retention of a retaining surface 32 situated at the upstream axial end of the platform 30.

(15) The fastening zone between the disc 40 and the retaining flange 50 being situated at the radial protrusions 46, therefore closer to the center of the disc, allows limiting the stresses exerted during the operation of the fan at sensitive surfaces such as the upstream axial end of the teeth 44. Moreover, this interface between the disc 40 and the retaining flange 50 being offset radially relative to the grooves in the disc, in comparison to known structures, the cantilevers 44c, usually allowing the fastening of the shroud to the upstream end of the disc teeth, can be eliminated. This allows liberating space at the upstream axial end of the teeth 44 of the disc. It is also possible to modify more freely the upstream axial end of the teeth 44, and therefore the upstream axial end of the platform 30, for example by providing an inclined wall 34 over the upstream end of the platform 30, the inclined wall 34 coming into contact with the tapered surface 44b of the tooth 44. It is thus possible to reduce the hub ratio in order to optimize the performance of the fan, and therefore of the turbomachine in which the fan is mounted.

(16) Although the present machine has been described by referring to specific embodiments, it is obvious that modifications and changes can be performed on these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the different embodiments illustrated/mentioned can be combined into additional embodiments. Consequently, the description and the drawings can be considered in an illustrative, rather than a restrictive sense.