FITTED PLATFORM FOR A TURBINE ENGINE FAN, AND A METHOD OF FABRICATING IT

Abstract

The invention provides a fitted platform (1) for positioning between two adjacent blades of an aviation turbine engine fan, said platform comprising a flow passage wall (10) made of composite material having a central portion (16) and first and second margins (18) each extending in a longitudinal direction of said wall, each margin extending over a determined distance (D) from the central portion (16) in a transverse direction of said wall, said flow passage wall comprising fiber reinforcement densified by a matrix, the platform being characterized in that the fiber reinforcement present in the central portion (16) presents three-dimensional weaving, and in that the fiber reinforcement present in the first and second margins (18) presents two-dimensional weaving, at least in part. The invention also provides a fan module, a turbine engine, and a method of fabricating such a platform.

Claims

1. A fitted platform for positioning between two adjacent blades of an aviation turbine engine fan, said platform comprising a flow passage wall made of composite material having a central portion and first and second margins each extending in a longitudinal direction of said wall, each margin extending over a determined distance from the central portion in a transverse direction of said wall, said flow passage wall comprising fiber reinforcement densified by a matrix, the platform being characterized in that the fiber reinforcement present in the central portion presents three-dimensional weaving, and in that the fiber reinforcement present in the first and second margins presents two-dimensional weaving, at least in part.

2. A platform according to claim 1, characterized in that the weave in the first and second margins is selected from: plain, satin, serge.

3. A platform according to claim 1, characterized in that each margin extends in the transverse direction of the flow passage wall from the central portion over a determined distance D such that a ratio D/L lies in the range 2% to 10%, where L is the width of the flow passage wall in the transverse direction of said wall.

4. A platform according to claim 1, characterized in that each margin presents a thickness e such that a ratio e/D lies in the range 5% to 50%, where D is the determined distance over which each margin extends in the transverse direction of the flow passage wall from the central portion.

5. A platform according to claim 1, characterized in that it has a bottom wall for resting on a fan disk and two side walls extending between the bottom wall and the flow passage wall of said platform.

6. A platform according to claim 1, characterized in that it is made of composite material and comprises fiber reinforcement densified by a matrix, the fiber reinforcement of the flow passage wall constituting a portion of the fiber reinforcement of the platform.

7. An aeroengine turbine engine fan module comprising at least two blades and at least one platform according to claim 1 positioned between two adjacent blades.

8. An aviation turbine engine including a fan module according to claim 7.

9. A method of fabricating a fitted platform according to claim 1, the method comprising the following steps: weaving a fiber preform to form the fiber reinforcement of the flow passage wall of the platform; and forming a matrix in the pores of said fiber preform.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other characteristics and advantages of the present invention appear from the following description made with reference to the accompanying drawings, which show embodiments having no limiting character. In the figures:

[0019] FIG. 1 shows a box-type fitted platform for a turbine engine fan;

[0020] FIG. 2 is a diagrammatic cross-section view of the fitted platform of FIG. 1; and

[0021] FIGS. 3A & 3B and 4A & 4B show respectively two example weaves at a margin of the flow passage wall.

DETAILED DESCRIPTION OF THE INVENTION

[0022] FIG. 1 shows an example of a fitted platform 1 for an aviation turbine engine fan. The platform 1 is positioned between two adjacent blades 2 (only one blade 2 is shown diagrammatically in dashed lines in FIG. 1) and it is mounted on a fan disk 3. The platform 1 shown in FIG. 1 is a platform made entirely out of composite material and it is of the box type, i.e. it presents a flow passage wall 10, a bottom wall 12, and two side walls 14 extending between the bottom wall 12 and the flow passage wall 10. The bottom wall 12 of the platform comes into contact with the fan disk 3 when the engine is stationary. The direction of the air stream entering into the turbine engine is indicated in the figure by arrow F. When the engine is in operation, the flow passage wall 10 of the platform defines the inside (relative to the longitudinal axis of the turbine engine, not shown) of the flow passage for the gas stream entering into the turbine engine.

[0023] The platform 1 may be constituted in full or in part by fiber reinforcement densified by a matrix. The fiber reinforcement may comprise carbon fibers or ceramic fibers. The matrix may be a ceramic matrix, or more often an organic matrix, and it may be obtained from a densification resin, for example.

[0024] FIG. 2 is a diagrammatic section view of the FIG. 1 platform 1. The flow passage wall 10 of the platform 1 has a central portion 16 and two margins 18. The margins 18 extend in the longitudinal direction of the flow passage wall 10, in this example over the entire length of the flow passage wall 10. The longitudinal direction of the flow passage wall 10 extends in the direction given by its long dimension, the transverse direction being perpendicular to the longitudinal direction. The flow passage wall 10 in this example extends transversely between its two margins 18.

[0025] In accordance with the invention, the flow passage wall 10 comprises fiber reinforcement densified by a matrix. In a portion corresponding to the central portion 16, the fiber reinforcement presents three-dimensional weaving. The portions of the fiber reinforcement corresponding to the margins 18 of the flow passage wall 10 present two-dimensional weaving, at least in part. By way of example, in the central portion 16, the fiber reinforcement may present an interlock or multilayer type weave, and in the margins it may present a satin, plain, or serge type weave. It should be observed that it is also possible to provide for mixed weaving in the fiber reinforcement for the margins 18, i.e. weaving that is two-dimensional over a fraction of the thickness of the margin 18 and three-dimensional over the remaining fraction of the thickness of the margin 18.

[0026] Each of the margins 18 may extend in the transverse direction of the flow passage wall 10 from the central portion 16 over a determined distance D. The distance D at a point of the flow passage wall 10 may be such that D/L lies in the range 2% to 10%, e.g. in the range 5% to 10%, where L is the width of the flow passage wall at the point under consideration. Naturally, and as for the platform 1 in FIG. 1, the width L may vary along the flow passage wall 10 so that the distance D may likewise vary along the flow passage wall 10. The thickness e of a margin 18 may be different from the thickness of the remainder of the flow passage wall 10. Under such circumstances, the thickness e of a margin 18 may be such that e/D lies in the range 5% to 50%, and for example in the range 5% to 10%.

[0027] Two examples of weaves in the zone A of the margins 18 as identified in FIG. 2 are described below respectively with reference to FIGS. 3A & 3B and with reference to FIGS. 4A & 4B. In these figures, the weft yarns are visible in section and are shown as being in a staggered configuration, such that a weft yarn layer T comprises two consecutive half-layers of weft yarns t.sub.1 & t.sub.2, t.sub.3 & t.sub.4, etc. The warp yarns are referenced c.sub.1 to c.sub.10. Throughout the specification and in all of the drawings, by convention and for reasons of convenience, it is stated and shown that it is the warp yarns that depart from their path in order to take hold of weft yarns in one or more layers of weft yarns. Nevertheless, these roles may be interchanged between warp and weft.

[0028] FIGS. 3A and 3B show respectively two weave planes of the weaving of the fiber reinforcement in the zone A in the proximity of a margin 18, in a first example. In this example, the fiber reinforcement of the entire central portion 16 presents a three-dimensional weave of interlock type, and the fiber reinforcement of the margins 18 presents a two-dimensional weave of the serge type. Eleven weft yarn layers T of the fiber reinforcement of the central portion 16 are shown, i.e. twenty-two half-layers of weft yarns t.sub.1 to t.sub.22. The fiber reinforcement at the margin 18 has ten weft yarn layers T, i.e. twenty half-layers of weft yarns t.sub.1 to t.sub.20.

[0029] In the example shown, the fiber reinforcement in the central portion 16 presents an interlock weave in which each warp yarn c.sub.1 to c.sub.10 interlinks three weft yarn half-layers. Furthermore, in the margin 18, the fiber reinforcement presents a conventional serge weave in which each warp yarn c.sub.1 to c.sub.10 takes hold of two weft yarns going from one side to the other of a single weft yarn layer T. At the margins 18, the weft yarn layers T are not interlinked by warp yarns c.sub.1 to c.sub.10. Thus, in the margins 18, a stack of two-dimensional fabric strips is obtained, each of which strips is connected to the central portion 16 by weaving. In the event of an impact leading to relative movements of the margins 18 of the platform 1 against the neighboring blades 2, delamination can occur between the fabric plies or strips that present two-dimensional weaving, i.e. the strip of fabric may separate from one another.

[0030] FIGS. 4A and 4B show two respective weave planes of the fiber reinforcement in the zone A in the proximity of a margin 18, in a second example. In this example, the fiber reinforcement of the entire central portion 16 presents an interlock weave, and the fiber reinforcement of the margins 18 presents a mixed weave with two portions 20 and 22 in the thickness of the margin 18 that present a (two-dimensional) serge weave, together with a portion 24 in the thickness of the margin 18 that presents a (three-dimensional) interlock weave.

[0031] As in the first example, the fiber reinforcement in the central portion 16 presents an interlock weave in which each warp yarn c.sub.1 to c.sub.10 interlinks three weft yarn half-layers. Thereafter, at the interface between the central portion 16 and the margin 18, the first two and the last two warp yarns c.sub.1 & c.sub.2 and c.sub.9 & c.sub.10 of the margin 18 follow a serge pattern in which each warp yarn takes hold of two weft yarns, and in which each warp yarn interlinks a single weft yarn layer T. The remaining warp yarns c.sub.3 to c.sub.8 continue their paths without changing pattern in the fiber reinforcement of the margin 18, interlinking three weft yarn half-layers with an interlock weave. In the portion 24, the weft yarn layers T are interlinked by the yarns c.sub.3 to c.sub.8. In the margins 18, the first two and the last two weft yarn layers T are not interlinked, nor are they linked with the portion 24. By using the weave shown herein by way of example, the margins 18 present a two-dimensional weave only in the portions 20 and 22. Thus, in this example, each margin 18 presents two strips of two-dimensional fabric in each portion 20 and 22; together with a strip presenting a three-dimensional weave in the portion 24. The above-mentioned strips in the portions 20, 22, and 24 are all connected to the central portion of the flow passage wall 10 by weaving.

[0032] In order to fabricate a platform 1 of the invention, it is possible to begin by weaving a fiber preform that is to form the fiber reinforcement of the platform. A box platform 1 as shown in FIG. 1 can be obtained from a single fiber preform. In a variant, it is possible to use a plurality of fiber preforms that are subsequently assembled together prior to densification, e.g. a fiber preform for the flow passage wall 10 and a fiber preform for the remainder of the platform. The fiber preform for the flow passage wall 10 is woven in compliance with the above-described weaving characteristics, e.g. using the above-described weave in the margins 18. Naturally, weaves other than those described above could be used without going beyond the ambit of the invention.

[0033] Finally, a matrix may be formed by any known method within the fiber preform of the platform 1, possibly after it has been shaped. For example, the platform 1 may be fabricated by injection molding resin into the fiber preform. This method is known as resin transfer molding (RTM). For this purpose, an injection mold is used having the shape of the platform 1 and in which the dry fiber preform is placed, after which resin under pressure is injected into the inside of the mold, the resin is solidified so as to form a matrix in the pores of the fiber preform, and the platform 1 as fabricated in this way is extracted from the mold.