EP2783079A1

EP2783079A1 - Aircraft engine air flow straightening vane and associated flow straightening structure

Info

Publication number: EP2783079A1
Application number: EP12795536.7A
Authority: EP
Inventors: Arnaud OUDIN; Bertrand Desjoyeaux; Nicolas Dezeustre; Olivier Kerbler
Original assignee: Aircelle SA
Current assignee: Safran Nacelles SAS
Priority date: 2011-11-24
Filing date: 2012-11-13
Publication date: 2014-10-01
Also published as: RU2014124910A; FR2983261B1; CA2856232A1; FR2983261A1; WO2013093258A1; US20140255178A1; CN103987924A; US9915157B2; BR112014012131A2

Abstract

This flow straightening vane (23) made of composite materials comprises a core made up of three-dimensional woven textile rods (36) which core is surrounded by a textile covering (39), this core and this covering being consolidated using a thermoset resin.

Description

Airflow rectification blade for an aircraft engine, and associated flow straightening structure

The present invention relates generally to the field of turbofan engines for aircraft and more particularly to the secondary flow recovery vanes, and to an associated flow recovery structure.

As is known per se, and shown in Figure 1 attached, a propulsion unit of a turbofan engine typically comprises an external structure 1 having an upstream portion 3 forming an air inlet, an intermediate portion 5 whose internal skin 6 housing form for the blower 7 of the engine, and a downstream portion 9 may incorporate thrust reversal means.

This nacelle also has an internal structure 11 comprising a fairing 13 of the engine 15.

The volume delimited in particular by the internal skin 6 of the external structure 1 and the fairing 13 of the internal structure 11, defines an annular air stream 17, often referred to as a "cold air vein", as opposed to the hot air generated by the engine 15.

The fan 7 consists essentially of a helix provided with blades 19, rotatably mounted on a rotating shaft connected and centered on a bearing 21. The bearing 21 is connected to the fan casing 6 by a transverse structure assembly marked 25 in FIG. extending radially in the cold air duct 17, such as structural arms can be distributed at 90 or 120 degrees for example.

In this same cold air stream 17 is a flow rectification structure comprising flow straightening vanes 23, also called OGV ("Outlet Guide Vanes"), for rearward straightening the flow of cold air generated by the blower 7.

Concepts are also known in which the paddle wheel

OGV replaces the structural arms, thus ensuring the two functions of flow rectification and connection of the bearing 21 with the fan casing 6.

So-called structural OGV wheels are known in which the OGVs are metallic.

Non-structural composite OGV wheels are also known, associated with metallic structural arms. The design of composite and structural OGVs, thus making it possible to overcome completely or partially the structural arms, poses an important difficulty to design and make the fasteners of these blades at their ends and the structural continuity of these fasteners with the body of the blades.

The present invention aims to provide composite material vanes for structuring flow straightening structure, which have an increased strength / weight ratio.

This object of the invention is achieved, as well as others which will become apparent in the light of the description which follows, with a flow straightening blade made of composite materials, comprising a core formed of three-dimensional woven textile bars, surrounded by of a textile envelope, this core and this envelope being consolidated by a thermosetting resin.

By virtue of these features, a flow straightening blade is obtained in which the three-dimensional woven fiber core provides high strength, and the textile wrap provides the desired shape as well as resistance to eventual impacts. all to run very advantageous weight.

According to other optional characteristics of the flow straightening blade according to the invention:

said textile bars have connection ends of the blade to the wheels of a flow straightening structure;

said ends have a shape included in the group comprising T-shaped, L-shaped, dovetailed, parallel to the blade plane, transverse to the blade plane, inclined with respect to the blade plane, folded or twisted;

the adhesive and the envelope are formed of fibers selected from the group consisting of carbon fibers, glass fibers and aramid fibers;

said resin is a compatible resin of an injection process selected from the group of thermosetting resins such as epoxy resins and polyimide resins or from the group of thermoplastic resins such as PEEK, PPS;

said textile is chosen from the group comprising woven, sewn or braided two-dimensional textiles and three-dimensional textiles; the core and the shell are interconnected by transverse fibers or transverse wires;

said blade comprises reinforcing elements chosen from the group comprising counterplates, inserts, a rigid element forming a leading edge and an anti-erosion coating;

said blade comprises one or more hollow zones;

said blade comprises one or more lightened nuclei;

- The soul ad presents a form e cho isie d s sleg rou pe including the shapes in parallel bars, H, H to several bars, O, W, M, X parallel bars, X, in K, inverted K, N, inverted N.

The present invention also relates to a flow straightening structure, comprising a smaller diameter wheel, a fan bearing mounted within this wheel, a larger diameter wheel, and a plurality of blades according to the present invention. the above, cooperating by their endings with these two wheels.

According to optional features of this flow straightening structure:

the envelopes of said vanes are joined;

said blades are interposed between the positions of the structural connecting arms between said bearing and said wheel of larger diameter.

Other characteristics and advantages of the present invention will emerge in the light of the description which follows, and on examining the appended figures, in which:

- Figure 1 is a longitudinal half-sectional view of a set of nacelle and engine of the prior art, commented in the preamble of the present description;

FIGS. 2, 3, 4, 5 are views respectively in perspective, from the side, in section along the line VV and in section along the line VI-VI of an embodiment of a flow straightening blade. according to the invention;

FIGS. 5a and 5b illustrate the manner in which a T-end web is produced;

FIG. 5c illustrates the manner in which a clevis end web is rotated about 90 ° with respect to the plane of the blade; FIGS. 6a, 6b, 6c are partial views in perspective of other embodiments of a flow straightening blade according to the invention;

FIGS. 6d, 6e, 6f are cross-sectional views analogous to the view of FIG. 5 of various possible structures of red fl ow blades according to the invention, and in particular of different ends of textile bars allowing the bonding these vanes with the wheels of a flow straightening structure;

FIG. 7 is a diagrammatic side view of the dawn of the figures

2 to 5, showing the preferred directions of recovery efforts, and

- Figures 8 to 18 are views similar to that of Figure 7 other embodiments of a flow straightening blade according to the invention.

In all of these figures, identical or similar references denote identical or similar organs or sets of members.

Note also that we have taken care to represent in these figures a reference to three axes X, Y, Z, these three axes being respectively representative of the longitudinal, transverse and vertical directions of the engine when it is installed on an aircraft .

For the sake of simplification in what follows, it will be assumed that the average plane of each blade is substantially parallel to the XZ plane, which is of course not the case in reality since precisely these vanes must have a certain angle of incidence. to allow flow recovery.

Referring now to Figures 2 to 5 and 7, which shows a flow rectification blade according to a first embodiment of the invention.

As can be seen in these figures, this blade 23 comprises a core 36 formed of two "textile bars" 37a and 37b, themselves obtained by fibers of glass or carbon or aramid woven in three dimensions.

According to a first variant, such "textile bars" can be obtained by three-dimensional weaving.

For example, such "textile bars" can be obtained from the company BITEAM (www.biteam.com), specialist in this kind of products. Three-dimensional weaving can be achieved by means of a chain and one or two fields respectively arranged in two or three substantially perpendicular directions of space (ie the same weft thread is conducted between the strings to cover the intertwining in all the directions of the plane transverse to the chains, that is to say son of frames d istincts realize interlacing, in the plane transverse to the chains, in two main directions, substantially perpendicular to each other).

According to a second variant, such "textile bars" can be obtained using a matrix braiding machine.

The two bars 37a and 37b are surrounded by a textile envelope 39, which can be formed from at least one layer of two-dimensional textile fibers woven or braided, stitched, or three-dimensional textile.

The woven two-dimensional textiles are obtained by weaving warp fibers and weft fibers substantially perpendicular to one another in the mean plane of the fold. These textiles are commonly called fabrics, canvas, taffeta, twill or satin by the skilled person according to the weaving pattern chosen.

The braided two-dimensional textiles are obtained by braiding fibers, grown according to their di ertion by a method of braiding and optionally fibers in a third longitudinal direction in the braiding direction, all the fibers being substantially in the plane. the fold.

The sewn two-dimensional textiles are obtained by superposition of two or more layers of fibers in different directions, the layers being linked by more or less spaced stitching points.

The three-dimensional textiles are formed of a superposition of layers of fibers interconnected by transverse fibers interweaving some of the fibers between the layers. These textiles are commonly referred to as 3D fabrics or 3D interlock fabrics, or layered interlock fabrics by those skilled in the art.

The fibers forming the aforementioned textile may be carbon, glass or aramid fibers, for example.

The envelope 39 is constituted by a stack of at least one of the aforementioned texti l es. When multiple layers are stacked, the orientation of each of them can be chosen different from the others.

The stack of folds constituting the envelope can also be linked together by additional wires transverse to the thickness such that by a so-called stitching process (or stitching including the family of stitches chain-type) or tufting or needling known elsewhere.

It is also possible to incorporate additional elements, such as inserts, plates, plywoods, leading edge elements, all of which may be, for example, metal alloys into the mold or subsequently to the flow straightening vane. or ceramic.

It is also possible to envisage placing on the leading edge of the flow straightening blade 23 an anti-erosion coating.

As can be seen in the various sketches the use of the principle of weaving or three-dimensional web braiding makes it possible to modify the geometries of the textile bars, and in particular the endings of the core, to obtain different forms of ends facilitating assembly.

This particularity of weaving or three-dimensional braiding provides multiple possibilities of shapes, with the advantage of providing continuity of the fibers from one part to another, and in particular string fibers substantially parallel to the longer length of the bars.

In a first configuration shown in FIGS. 2, 3 and 4, the bars 37a and 37b of the core 36 may be shaped so that they have, at their respective ends, T-shaped shapes 41a, 41b, or shapes. clevis 43a, 43b, respectively oriented tangentially and radially with respect to the axis A of the turbojet, that is to say in this case in two different directions XY and YZ but both transverse to the plane XZ, and provided with orifices allowing the connection of these terminations respectively to the large and small wheels 29, 27 of the flow rectification assembly.

More precisely, and as can be seen in FIGS. 5a and 5b, this T-shape of the ends of the textile bars 37 can be obtained by producing a three-dimensional weave with a two-branched untied zone 42a, 42b, forming a kind of Y (Figure 5a), which is then removed by a forming operation (Figure 5b) to obtain the T-ends 41a, 41b.

The three-dimensional weaving and braiding techniques make it possible, in the same way, to change the distribution of the warp fibers of the textile bar while maintaining the orientation thereof substantially parallel to the direction of greater length of the bar. This is illustrated in FIG. 5c, on which a textile bar can be seen comprising two rectangular sections 42c, 42d, and rotated by 90 degrees with respect to each other: such a configuration may correspond, for example, to the ends 43a, 43b of the bars of the blade shown in Figures 2 to 5.

The transition from section 42c to section 42d is effected by a substantially square intermediate zone 42e, the distribution of chain fibers 42f being arranged to allow this transition.

It can also be seen in Figures 2 and 4 that the envelope 39 may comprise tangential rolled portions 45a, 45b and 47a, 47b, which may extend over a circumferential length sufficiently large to be joined from one blade to the other .

These envelopes can thus participate in the consolidation of large 29 and small 27 wheels and / or in the constitution of the aerodynamic shape of the inner and / or outer shell.

It will also be noted in FIG. 5 that the flow straightening vane may comprise, between the bars 37a and 37b, an area 49 which may be either hollow or filled with a lightened material such as rigid cell foam. closed, such as low density foams and compatible material of the consolidation resin and operating temperatures.

For example, it is possible to use foams with densities of between 40 kg / m 3 and preferably less than 250 kg / m 3 of polyurethanes, polyvinyl chloride or polymethacrylic imide, etc.

The presence of such a slack is allowed perm and avoid filling the cavity 49 with resin during the manufacture of the flow straightening blade, thus leading to a great saving in weight: a such foam is indeed 4 to 20 times lighter than the resin.

The blade 23, consisting of the entire core 36, the casing 39, any lightened nuclei, is consolidated by impregnation resin and hardening, giving the dawn all its rigidity, strength and shape.

The various elements prepared are placed inside a mold in which resin is injected. An RTM injection process can be used in a rigid closed mold to obtain all of the surfaces with precise dimensions. It will also be possible to use a method of vacuum infusion type, with a flexible tooling part, or any alternative infusion molding environment.

In a mode of realization, one can realize a hollow zone in the dawn, either by introduction of a tooling element by one end, and extraction during demolding, or by a core inserted between the two faces of the envelope, and removal of the core after demolding by melting or dissolution thereof.

The resin will be chosen as a function of the blade utilization temperature, in the families of thermosetting epoxy resins, polyimide resins, polyester resins, vinylester resins, cyanate ester resins or those derived from these families, or else in families of thermoplastic resins such as PPS PEEK. PEKK, PEI.

Finally, to enable the blades to be connected to the inner and outer wheels 29 and with tight geometrical tolerances, it will be possible to machine all or part of the end zones in order, for example, to cut off the contour of the screeds, surface the flanks of screeds, and pierce the fastener passages.

As can be understood in the light of the foregoing, the flow straightening blade according to the invention comprises a structural part strictly speaking formed by the core 36, which is extremely resistant due to its 3D weaving characteristics. with carbon fiber, glass or aramid, and very light.

The flow straightening blade according to the invention also comprises a part defining its aerodynamic profile, obtained by a two-dimensional or three-dimensional textile envelope.

The cooperation of this soul 36 and of this envelope 39, secured together by the resin, provides a flow recovery blade which is both light and very strong, which is perfectly suitable for use in the flow stream. cold air 17, to connect the engine to the suspension mast of the nacelle.

Figures 6a, 6b, 6c show possible variants for the ends of the straightening vanes.

In Figure 6a, one can see substantially radial clevises 43a, 43b, having an inclination of several degrees with respect to a plane passing through the axis A of the nacelle, and with respect to the XZ plane.

In FIG. 6b, we can see terminations 41a, 41b at L, both extending on the same side with respect to the blade, in one direction substantially tangential, that is, in a direction substantially parallel to the XY plane.

In Figure 6c, there can be seen enlarged terminations 41a, 41b, substantially having a dovetail shape.

These variants are of course not limiting, and can be combined with each other.

Figures 6d, 6e, 6f show alternative structures for the straightening vanes.

In FIG. 6d the envelope 39 consists of tubular braids which encapsulate the textile bars 37a, 37b and a foam core 51.

In FIG. 6e, the envelope 39 is made from an open fabric folded around the blade, for example at the leading edge 53.

In Fig ure 6f, the envelope 39 consists of two subsets 39a, 39b each constituting one of the two faces of the blade.

According to a variant of the association of the bars 36 and the envelope 39, the envelope can be connected to at least one of the bars, by additional connections, through the thickness.

Thus, according to a first variant, carbon fibers or aramid or glass, are inserted transversely through the casing 39 and penetrate into at least a portion of the bars 36 for example with a tufting method, or needling, or crossing the bars completely with the same method or a stitching process.

According to a second variant, thin rigid elements are inserted transversely to the plane of the envelope 39, these thin rigid elements possibly being pultruded fiberglass, aramid or carbon composite needles, these rigid elements may also be metal wires in the form of fine nails or staples. These rigid elements may be inserted in a nailing or Z-pinning process or the like.

In all of Figures 8 to 18, there is shown various possible variants of the core 36, the arrows in these figures indicating the preferred directions of the efforts taken by the bars forming the core.

Specifically, straight arrows indicate force transmissions, and curved arrows indicate moment transmissions.

We can thus see: - In Figure 8: an H-shaped core structure, to resist the axial forces (X direction) and radial (Z), giving the blade a special resistance to shocks objects likely to flow into the vein d 'cold air,

- In Figure 9: a H-bar structure, further allowing to resist tangential moments (moments around the Y axis),

in FIG. 10: a structure in O, making it possible to withstand radial (Z) and axial (X) forces, as well as a tangential moment (around the Y axis),

- In Figure 1 1: a structure in W, for resisting radial and axial forces, as well as a tangential moment on the small wheel side 27,

- In Figure 12: a structure in M, for resisting radial and axial forces, and a tangential moment on the ferris wheel side 29,

in FIG. 13: an X-shaped structure with parallel bars, making it possible to withstand radial and axial forces, as well as a tangential moment on the small side 27 and the large 29 wheel,

- In Figure 14: an X-shaped structure, to resist radial forces and a tangential moment small side 27 and large 29 wheel,

- In Figures 15 and 16: a structure respectively in K and inverted K, for resisting radial and axial forces, as well as a tangential moment,

- In Figure 17: a structure in M, for resisting radial forces and a tangential moment on the downstream side of the small wheel 27 and upstream side of the ferris wheel 29, and

- In Figure 18: an inverted N structure, for resisting radial forces and a tangential moment upstream side of the small wheel 27 and downstream side of the ferris wheel 29.

Of course, the present invention is not limited to the embodiments described and shown, provided as simple examples.

Claims

1. A flow straightening vane (23) of composite materials, comprising a core formed of textile bars (37a, 37b) woven in three dimensions (36), surrounded by a textile envelope (39), this core and this envelope being consolidated by a cured resin.

2. blade (23) according to claim 1, wherein said textile bars (37a, 37b) have ends (41a, 41b, 43a, 43b) connecting the blade (23) to the wheels (27, 29) d a flow recovery structure.

3. blade (23) according to claim 2, wherein said ends have a shape included in the group consisting of T-shaped, L-shaped, dovetail, parallel to the blade plane, transverse to the blade plane , inclined to the plane of dawn, folded or twisted.

The blade (23) according to any one of the preceding claims, wherein said core (36) and said casing (39) are formed of fibers selected from the group consisting of carbon fibers, glass fibers, and fiber fibers. aramid.

A blade (23) according to any one of the preceding claims, wherein said resin is a compatible resin of an injection process selected from the group of thermosetting resins such as epoxy resins and polyimide resins or in the group thermoplastic resins such as PEEK, PPS.

The blade (23) according to any one of the preceding claims, wherein said textile is selected from the group consisting of woven, sewn or braided two-dimensional textiles, and three-dimensional textiles.

7. blade (23) according to any one of the preceding claims, wherein the core (36) and the casing (39) are interconnected by transverse fibers or transverse son.

8. blade (23) according to any one of the preceding claims, comprising reinforcing elements selected from the group comprising counterplates, inserts, a rigid leading edge element and an anti-erosion coating.

9. blade (23) according to any one of the preceding claims, comprising one or more hollow zones.

10. blade (23) according to any one of the preceding claims, comprising one or more lightened cores (49).

11. A blade (23) according to any one of the preceding claims, wherein said core (36) has a shape selected from the group consisting of parallel bars, H, H bars, O, W , in M, in X with parallel bars, in X, in K, in inverted K, in N, in N inverted.

A flow straightening structure, comprising a smaller diameter wheel (27), a fan bearing (21) mounted within said wheel (27), a larger diameter wheel (29), and a plurality of blades (23) according to claim 2, cooperating at their ends (41a, 41b, 43a, 43b) with these two wheels (27, 29).

13. flow straightening structure according to claim 12, wherein the envelopes (39) of said vanes (23) are contiguous.

14. flow straightening structure according to one of claims 12 or 13, wherein said vanes are interposed between the structural connecting arm positions between said bearing and said larger diameter wheel (29).