Turbomachine blade having a metallic leading edge

A turbomachine blade includes a blading made of composite material with a fibrous reinforcement densified by a matrix and a metal leading edge formed by a metal foil, the foil having an intrados fin and an extrados fin which extend respectively over intrados and extrados faces of the blading by conforming to an airfoil of the blade, wherein the blade also includes at least one unidirectional fabric ply made of composite material on the leading edge between the blading and the metal foil, each unidirectional fabric ply extending at least partially over the intrados and extrados faces of the blading.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage of PCT/FR2021/051067, filed Jun. 15, 2021, which in turn claims priority to French patent application number 20 06378 filed Jun. 18, 2020 and French patent application number 20 06676 filed Jun. 25, 2020. The content of these applications are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to the general field of blades for aeronautical gas turbine engines or aeronautical turbomachines made of composite material and more particularly to turbomachine blades with a metal leading edge.

PRIOR ART

In order to protect the composite blading of a blade from abrasion, erosion and/or impacts with a foreign body, the blades comprise a reinforced leading edge, and more particularly a one-piece leading edge made of titanium.

This titanium leading edge is assembled by bonding on the blading. Nevertheless, this type of leading edge incurs significant material and manufacturing costs as well as non-compliances throughout its lifecycle.

Indeed, the cost of the titanium material is high, and the manufacture of the blade entails many steps as well as material scraps. Moreover, during the assembly of the titanium leading edge on the blading, the surface of the blading must be prepared before bonding the leading edge and the latter requires a prior passage in a long autoclave cycle. It is also necessary to adapt the cavity of the blading receiving the leading edge which is very often too wide or too narrow, which leads to corrugations and/or striations at the level of the fins of the blading.

During the manufacture of intermediate parts for making a blade comprising such a leading edge, non-compliances on the part at the start of mounting can also be observed, whereas the intermediate part (titanium leading edge) was compliant.

It is also difficult to repair such a damaged leading edge without changing the entire leading edge.

It is therefore desired to have an aeronautical turbomachine blade that is less expensive during its manufacture and maintenance and that is more easily repairable.

DISCLOSURE OF THE INVENTION

The invention relates to a turbomachine blade comprising a blading made of composite material with a fibrous reinforcement densified by a matrix and a metal leading edge formed by a metal foil, the foil having an intrados fin and an extrados fin which extend respectively over intrados and extrados faces of the blading by conforming to an airfoil of the blade, characterized in that the blade also comprises at least one unidirectional fabric ply made of composite material on the leading edge between the blading and the metal foil, each fabric ply extending at least partially over the intrados and extrados faces of the blading.

Such a leading edge can be easily assembled on the blading and repaired without touching or damaging the composite structure of the blading, because it suffices to replace the damaged and/or non-compliant foil with another foil that will only be in contact with the unidirectional fabric plies. Moreover, the leading edge of the invention allows designing, producing and repairing the blade at a lower cost. Indeed, the metal foil has a thickness much smaller than that of a one-piece titanium leading edge, the costs of the material are therefore reduced during the manufacture or during the repair of the blade.

It is also easier to adapt to particular blade geometry constraints with this type of leading edge, such as the reinforcement of one of the faces of the blade by extending the metal foil on the intrados or extrados face of the blading without modifying the inner structure of the blading.

According to one embodiment of the invention, the metal foil extends over a first length on the intrados face of the blading and over a second length on the extrados face of the blading.

This allows designing a blade whose metal reinforcement provided by the foil extends over a greater length on the intrados (or extrados) face compared to the extrados (or intrados) face of the blading.

According to another embodiment of the invention, the first and second lengths are equal.

This allows obtaining a leading edge symmetrical with respect to an axis connecting the leading edge and the trailing edge of the blade.

According to one particular characteristic of the invention, each unidirectional fabric ply extends over an entire inner surface of the intrados and extrados fins of the foil.

This allows not having direct contact between the metal foil and the blading. Thus, the replacement of the metal foil will be simplified, because it will not affect the inner structure of the blading and there will be no need to prepare the surface of the blading before laying the new foil.

According to one embodiment of the invention, the blade comprises a plurality of unidirectional fabric plies made of composite material on the leading edge between the metal foil and the blading, the plies of the plurality of fabric plies being draped over each other and extending at least partially over the intrados and extrados faces of the blading.

The unidirectional fabric plies allow protecting the inner structure of the blading in case of damage to the leading edge and of replacement of the metal foil. Moreover, since the plies are draped over each other, the corrugation or striation phenomena that may occur between the plies of the plurality of plies during the manufacture, use or repair of the blade are avoided.

According to one particular characteristic of the invention, an adhesive film is present between said at least one unidirectional fabric ply and the metal foil.

According to another particular characteristic of the invention, once the draping of the unidirectional fabric plies has been carried out, the metal foil and the rest of the blading are co-injected.

According to another particular characteristic of the invention, an adhesive film is present between said at least one unidirectional fabric ply and the blading.

These different characteristics (adhesive film, co-injection and draping) allow holding in place the metal foil on the unidirectional fabric plies, and holding in place the unidirectional plies on the blading.

According to another particular characteristic of the invention, the composite material of each unidirectional fabric ply comprises Kevlar fibers.

According to another particular characteristic of the invention, the blading is a three-dimensional part woven with glass fibers, the weaving can be partial or total.

According to another particular characteristic of the invention, the metal foil has a thickness comprised between 0.1 mm and 0.5 mm on the intrados and extrados faces.

According to another particular characteristic of the invention, said at least one unidirectional fabric ply has a thickness comprised between 0.15 mm and 0.25 mm.

According to another particular characteristic of the invention, the set of unidirectional fabric plies has a thickness comprised between 0.2 mm and 1 mm.

According to another particular characteristic of the invention, the blade constitutes an outlet guide vane, an inlet guide vane, a fan blade or a variable-pitch blade.

Another object of the invention is a method for repairing a turbomachine blade according to the invention, comprising the removal of the metal foil, the preparation of a surface of a new metal foil and the positioning of said new metal foil on the at least one unidirectional fabric ply.

DESCRIPTION OF THE EMBODIMENTS

The blade represented inFIGS.1to3can for example be a fixed blading or a flow straightener.

FIG.1schematically and partially represents a blade100according to the invention. The blade100comprises a blading140which extends along a longitudinal direction L, corresponding to a radial direction when the blade100is mounted in a turbomachine, between an inner platform141and an outer platform142. The blading140extends along a transverse direction T between a leading edge150and a trailing edge151.

The blading140is made of three-dimensional composite material, and more particularly of composite material with a fibrous reinforcement densified by a matrix. The fibrous reinforcement can comprise carbon fibers, and the matrix can be of the organic type and obtained from a densification resin. Alternatively, the fibrous reinforcement can comprise woven glass fibers.

The leading edge150of the blading140is covered by a metal foil120placed on the blading140by conforming to an airfoil of the blading140.

At least one unidirectional fabric ply made of composite material (not represented inFIG.1) is placed between the blading140and the foil120on the leading edge150.

FIG.2schematically and partially represents a cross-sectional view of the blading240of a blade200, along the plane II ofFIG.1, according to one embodiment of the invention.

The metal foil220comprises an intrados fin221and an extrados fin222which respectively extend over part of the intrados face241and part of the extrados face242of the blading240. The fins221and222are integrated into the blading240so that they conform to the airfoil of the blade200by defining part of this airfoil.

According to the invention, the blade200also comprises at least one unidirectional fabric ply made of composite material230placed between the metal foil220and the blading240. In the example ofFIG.2, a single ply230is represented. This fabric ply230allows not having a direct contact between the foil220and the fibrous structure of the blading240.

In the example ofFIG.2, the foil220and the fabric ply230extend over the same length on the intrados face241and on the extrados face242of the blading240. The fabric ply230therefore extends over the entire inner surface of the intrados221and extrados222fins of the foil220. The foil220is also symmetrical with respect to an axis extending between the leading edge250and the trailing edge of the blade200.

The fabric ply230has a thickness comprised between 0.15 mm and 0.25 mm. The metal foil220has a thickness comprised between 0.1 mm and 0.5 mm.

FIG.3schematically and partially represents a sectional view of the blading340of a blade300according to another embodiment of the invention.

The metal foil320always comprises an intrados fin and an extrados fin which extend respectively over part of the intrados face341and part of the extrados face342of the blading340. The fins are always integrated into the blading340so as to conform to the airfoil of the blade300.

In the example represented, the blade300comprises a plurality of unidirectional fabric plies330. Particularly, the example ofFIG.3comprises three plies331,332and333. The plies331,332and333are draped over each other. The draping can for example be made from single unidirectional plies pre-impregnated with an epoxy resin.

In this example, the foil320extends over a first length L1on the intrados face341of the blading340and over a second length L2on the extrados face342of the blading340. The foil320is therefore asymmetrical with respect to the axis extending between the leading edge350and the trailing edge of the blade300. In this example, the plies331,332,333extend over the same lengths L1and L2on the intrados341and extrados342faces of the blading300. But they can also extend over lengths greater than L1for the intrados face341and greater than L2for the extrados face342of the blading340, which allows protecting the blading340during the assembly and/or removal of the foil320during the manufacture or repair of the blade300. The lengths L1and L2can also vary over the height of blade300and be reversed in terms of proportions, that is to say L1can be greater than L2and vice versa.

The plurality of plies330has for example a thickness comprised between 0.2 mm and 1 mm, and the metal foil320between 0.1 mm and 0.5 mm.

Regardless of the embodiment, in order to fix the foil on the blading, an adhesive film can also be present between the metal foil and the unidirectional fabric plies.

Regardless of the embodiment, in order to fix the foil on the blading, the metal foil can be co-fired with the blading comprising the blading and the unidirectional fabric plies after draping the fabric plies.

Regardless of the embodiment, in order to fix the fabric plies on the blading, the plies which are pre-impregnated with a resin can be draped together. During firing, the resin of the pre-impregnated plies will polymerize and cure.

Regardless of the embodiment of the invention, the material forming the metal foil can comprise an alloy of titanium and/or aluminum.

Regardless of the embodiment of the invention, the composite material of the unidirectional fabric plies comprises Kevlar fibers. The advantage of Kevlar is to have a high resistance to impact, which allows protecting the blade, for example in the event of impact with birds.

Regardless of the embodiment of the invention, the blading can be a three-dimensional part that can be derived from a three-dimensional fiber weaving. It can for example be woven from organic fibers, such as carbon fibers, or from glass fibers. The fibers are then densified by a matrix which can be of the organic type.

Regardless of the embodiment, the blade can constitute an outlet guide vane, an inlet guide vane, a fan blade or a variable—pitch blade. And more particularly, the blade can constitute any fan blade at the level of the low-pressure compressor of a turbomachine.

The invention also relates to a method for repairing a blade according to the invention.FIG.4shows the different steps of an example of a repair method according to the invention.

The first step401of the method consists in removing the metal foil from the blade. This foil can for example be damaged following the use of the blade. To remove the foil, it can for example be peeled.

In a second step402, the surface of the new metal foil is prepared.

In a third step403, a new foil is positioned and assembled on the leading edge of the blade. The new foil can be assembled on the unidirectional fabric plies by bonding or by co-firing of the new foil, the fabric plies and the blading. The co-firing is for example carried out in an autoclave so that the resin polymerizes throughout the part.

The expression “comprised between . . . and . . . ” must be understood as including the bounds.