Composite blade with additional variable density leading edge

Abstract

A method of manufacturing a composite blade with an additional metallic leading edge for a gas turbine aero-engine, comprising: producing a composite blade body (10) comprising, in the longitudinal direction (D L ), a root portion (11), a shank portion (12) and an airfoil portion (13); manufacturing, by additive manufacturing, a leading edge portion (200) extending longitudinally between a lower end (206) present at the shank portion (12) of the composite blade body (10) and an upper end (208) present at a tip end (15) of the airfoil portion (13); bonding the manufactured leading edge (200) to the most forward edge portion (13a) of the airfoil of the composite blade body (10). The leading edge (200) comprises a first portion (210) of a first metallic material extending from the lower end (206) of the leading edge to an intermediate position (207) located between the lower end (206) and the upper end (208) of the leading edge, and a second portion (220) of a second metallic material extending from the intermediate position (207) to the upper end (208) of the leading edge, the second metallic material having a density greater than the density of the first metallic material.

Description

Technical Field

[0001] The present invention relates to the general field of manufacturing composite blades comprising a metal leading edge for gas turbine aero-engines. Background Art

[0002] The presence of a metal leading edge on a composite blade of a gas turbine aircraft engine provides protection for the composite blade assembly from foreign object impacts, such as bird strikes. This is particularly true for the active fan blades of a gas turbine aircraft engine, which are exposed to ingestion by birds, hail, ice, etc.

[0003] The manufacture of the above-mentioned blades firstly consists in producing a "blade body" of composite material comprising a fiber reinforcement densified with a matrix generally obtained from a thermosetting (TS) or thermoplastic (TP) resin.

[0004] Once the composite blade body is obtained, a protective metal leading edge must be assembled at its leading edge. To this end, a metal strip produced by mechanical methods such as stamping, forming, or electroforming is bonded to the leading edge of the composite blade. This operation can be performed in a mold to ensure proper adhesion of the strip. Examples of composite blades with metal leading edges are described in US 2007 / 092379 and US 2016 / 0167269.

[0005] To reduce weight, the additional leading edge is usually made of titanium. Although titanium has good mechanical strength, high-speed impacts of foreign objects (especially birds) on the titanium leading edge can still cause it to deform (bend). One solution is to increase the stiffness of the leading edge by increasing its thickness or by using a denser material. However, in this case, the total weight of the leading edge increases significantly, and therefore the centrifugal forces on the blade composite material also increase significantly, especially at the blade root, which is a critical area for static stresses on the blade. Summary of the Invention

[0006] The main object of the present invention is therefore to propose a method for manufacturing a composite blade with a metal leading edge which does not have the above-mentioned drawbacks.

[0007] This object is achieved in the present invention by a method for producing a composite blade with an attached metal leading edge for a gas turbine aero-engine, said method comprising:

[0008] - producing a composite blade body comprising, in a longitudinal direction, a blade root portion, a blade petiole portion and an airfoil body portion, the airfoil body portion extending longitudinally between the blade petiole portion and the airfoil body tip and extending transversely between a leading edge portion and a trailing edge portion;

[0009] - manufacturing, by additive manufacturing, a leading edge portion extending longitudinally between a lower end of a petiole portion present in the composite blade body and an upper end present at the tip end of the airfoil shaped body portion;

[0010] - bonding the manufactured leading edge to the leading-most portion of the composite blade main airfoil body,

[0011] It is characterized in that the leading edge includes a first portion of a first metal material, the first portion extending from the lower end of the leading edge to a middle position between the lower end and the upper end of the leading edge, and a second portion of a second metal material, the second portion extending from the middle position to the upper end of the leading edge, and the density of the second metal material is greater than the density of the first metal material.

[0012] In this way, a composite blade is obtained with a leading edge of variable density, the density of which, therefore, the stiffness, is greatest in the upper part of the blade, corresponding to the part of the blade most sensitive to foreign body impact. The leading edge is less dense in the lower part of the blade, which is less exposed and / or less sensitive to foreign body impact. The resulting blade has excellent impact resistance in the area to be reinforced to prevent the ingestion of foreign matter, while not significantly affecting the overall weight of the blade, given the presence of the less dense section. This also avoids increasing the static stresses caused by centrifugal forces in the petiole, an area of ​​concentrated force in the composite blade structure.

[0013] According to a particular feature of the method according to the invention, the first portion extends longitudinally at a height corresponding to 30% of the total airflow height, while the second portion extends longitudinally at a height corresponding to 70% of the total airflow height.

[0014] According to another particular characteristic of the method according to the invention, the first material is steel or titanium, and the second material is a nickel or cobalt alloy.

[0015] According to another particular characteristic of the method according to the invention, said first material is titanium and said second material is steel.

[0016] The invention also relates to a method for producing a composite blade with an attached metal leading edge for a gas turbine aero-engine, the method comprising:

[0017] - producing a composite blade body comprising, in a longitudinal direction, a blade root portion, a blade petiole portion and an airfoil body portion, the airfoil body portion extending longitudinally between the blade petiole portion and the airfoil body tip and extending transversely between a leading edge portion and a trailing edge portion;

[0018] - manufacturing, by additive manufacturing, a leading edge portion extending longitudinally between a lower end of a petiole portion present in the composite blade body and an upper end present at the tip end of the airfoil shaped body portion;

[0019] - bonding the manufactured leading edge to the leading-most portion of the composite blade main airfoil body,

[0020] Characterized in that the leading edge includes a first portion of a first metal material, the first portion extending from the lower end of the leading edge to a first intermediate position between the lower end and the upper end of the leading edge, a second portion of a second metal material, the second portion extending from the first intermediate position to a second intermediate position, and a third portion of a third metal material, the third portion extending from the second intermediate position to the upper end of the leading edge, the density of the second metal material being greater than the density of the first metal material and the third metal material.

[0021] In this way, a composite blade is obtained with a leading edge of variable density, the density of which, therefore, the stiffness, is greatest in the upper part of the blade, corresponding to the part of the blade most sensitive to foreign body impact. The leading edge has a lower density in the lower part of the blade, which is less exposed and / or less sensitive to foreign body impact. The resulting blade has excellent impact resistance in the area to be reinforced to prevent the ingestion of foreign matter, while not significantly affecting the overall weight of the blade, given the presence of two less dense sections. This also avoids increasing the static stresses generated by centrifugal forces, particularly in the petiole, where these forces are concentrated in the composite blade structure.

[0022] According to a particular feature of the method of the invention, the first portion extends longitudinally at a height corresponding to 30% of the total airflow height, while the second portion extends longitudinally at a height corresponding to 60% of the total airflow height, and the third portion extends longitudinally at a height corresponding to 10% of the total airflow height.

[0023] According to another particular feature of the method of the present invention, the first and third metal materials are steel or titanium, and the second metal material is nickel or a cobalt alloy.

[0024] According to another particular feature of the method of the present invention, the first and third metal materials are titanium, and the second metal material is steel.

[0025] Another subject of the invention is a composite blade with an attached metal leading edge for a gas turbine aircraft engine, the blade comprising a composite blade structure, the blade structure longitudinally comprising a blade root, a blade shank and an airfoil body, the airfoil body extending longitudinally between the blade shank and the blade tip and transversely between a leading edge portion and a trailing edge, the leading edge being bonded to the leading edge portion of the airfoil body of the composite blade structure, the leading edge extending longitudinally between a lower end present at the blade shank of the composite blade structure and an upper end present at the tip of the blade structure, characterized in that the leading edge comprises a first portion of a first metal material extending from the lower end of the leading edge to a position intermediate between the lower and upper ends of the leading edge, and a second portion of a second metal material extending from the intermediate position to the upper end of the leading edge, the density of the second metal material being greater than the density of the first metal material.

[0026] The blade of the present invention thus comprises a leading edge with variable density, the density of which, therefore, the stiffness, is greatest in the upper part of the blade, corresponding to the part of the blade most sensitive to foreign body impacts. The leading edge has a lower density in the lower part of the blade, which is hardly exposed and / or less sensitive to foreign body impacts. The resulting blade has excellent impact resistance in the area to be reinforced to prevent the ingestion of foreign bodies, while not significantly affecting the overall weight of the blade, given the presence of the less dense part. This also avoids increasing the static stresses caused by centrifugal forces in the petiole, which is the area of ​​force concentration in the composite blade structure.

[0027] According to a particular feature of the blade according to the invention, the first portion extends longitudinally at a height corresponding to 30% of the total airflow height, while the second portion extends longitudinally at a height corresponding to 70% of the total airflow height.

[0028] Another subject of the invention is a composite blade with an attached metal leading edge for a gas turbine aircraft engine, the blade comprising a composite blade structure comprising, in the longitudinal direction, a blade root, a blade shank and an airfoil body, the airfoil body extending longitudinally between the blade shank and the blade tip and transversely between a leading edge portion and a trailing edge, the leading edge being bonded to the leading edge portion of the airfoil body of the composite blade structure, the leading edge extending longitudinally between a lower end present at the blade shank of the composite blade structure and an upper end present at the blade tip of the blade structure, characterized in that the leading edge comprises a first portion of a first metal material extending from the lower end of the leading edge to a first intermediate position between the lower and upper ends of the leading edge, a second portion of a second metal material extending from the first intermediate position to a second intermediate position, and a third portion of a third metal material extending from the second intermediate position to the upper end of the leading edge, the second metal material having a density greater than that of the first and third metal materials.

[0029] The blade of the present invention thus comprises a leading edge with variable density, with the density, and therefore stiffness, being greatest in the upper portion of the blade, corresponding to the portion of the blade most sensitive to foreign body impact. The leading edge has a lower density in the lower portion of the blade, which is less exposed and / or less sensitive to foreign body impact. The blade thus has excellent impact resistance in the area to be reinforced to prevent the ingestion of foreign matter, while, given the presence of two sections of lower density, not significantly affecting the overall weight of the blade. This also avoids increasing the static stresses generated by centrifugal forces, particularly in the petiole, where these forces are concentrated in the composite blade structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic perspective view of a composite blade with an additional metal leading edge according to one embodiment of the present invention.

[0031] Figure 2 is an exploded schematic perspective view showing the assembly of a metal leading edge to a composite blade body.

[0032] Figure 3 is a schematic perspective view of a composite blade with an additional metal leading edge according to another embodiment of the present invention. DETAILED DESCRIPTION

[0033] The invention is applicable to manufacturing composite blades with metal leading edges for gas turbine aircraft engines.

[0034] Combined with fan blades (such as Figure 1 The method according to the present invention is described for manufacturing a blade 30) shown in FIG. 1 , which comprises a composite blade structure 100 having a longitudinal direction DL The blade root 110, the petiole 120 and the transverse direction D between the leading edge 200 and the trailing edge 132 are included. T Extended airfoil shaped body 130. Airfoil shaped body 130 also includes a lower surface 133, an upper surface 134 and a tip 135. Leading edge 200 is comprised of a strip of metallic material bonded to a forward-most portion 136 of airfoil shaped body 130. With the exception of leading edge 200, blade 30 is made of a composite material.

[0035] The method for manufacturing a blade begins by manufacturing the blade body from a composite material consisting of a matrix-densified fiber-reinforced material. "Blade body" refers to the main body of a blade made entirely of composite material, including most of the components of the final blade, namely the root, petiole, and airfoil, as described above, with the exception of the leading edge, which consists of a metal strip added to the blade body, as described below.

[0036] The blade body is made of a fiber preform that can be obtained in various ways known to those skilled in the art. Typically, the preform can be directly obtained by three-dimensional (3D) weaving of yarns (e.g., formed of carbon fibers) or by laminating two-dimensional fiber fabrics. The document US 2005 / 084377 describes in detail the manufacture of fan blades using composite materials that are made of fiber-reinforced materials formed by three-dimensional weaving and densified with a matrix. In the examples described herein, the fan blade preform is obtained by 3D weaving of carbon fiber yarns.

[0037] In a known manner, the blade preform is impregnated with a liquid composition containing a matrix material precursor. The precursor is usually in the form of a polymer, for example a resin optionally diluted in a solvent. The preform is placed in a mold, which can be sealed, the outer shell of which has the shape of the molded blade body and can have a twisted shape, in particular corresponding to the final shape of an airfoil body with an aerodynamic profile. The mold is closed and a liquid matrix precursor (for example an epoxy resin) is injected into the entire shell to impregnate all the fiber parts of the preform. The impregnation of the blade fiber preform can be achieved in particular by the well-known resin transfer molding method (RTM).

[0038] The conversion of the precursor into a matrix (e.g. by curing) is generally carried out by a thermal treatment, by heating the mold after removing any solvent and crosslinking the polymer, so that the preform held in the mold has a shape that matches the aerodynamic profile. The matrix can be obtained in particular from an epoxy resin, such as the PR 520 high-performance epoxy resin sold by CYTEC, or from a liquid precursor of a carbon or ceramic matrix.

[0039] For the formation of a carbon or ceramic matrix, a heat treatment requires the pyrolysis of an organic precursor to convert the organic-based matrix into a carbon or ceramic matrix, depending on the precursor used and the pyrolysis conditions. For example, the liquid carbon precursor can be a resin with a relatively high char content, such as a phenolic resin, while the liquid ceramic precursor for SiC can be a resin of the polycarbosilane (PCS), polytitanium carbosilane (PTCS), or polysilazane (PSZ) type, in particular. Several consecutive cycles from impregnation to heat treatment can be performed to achieve the desired degree of densification.

[0040] After the matrix is ​​formed, the part is ejected from the mold. It is then trimmed to remove excess resin and machine the chamfers. No further machining is required because the molded part meets the required dimensions. Figure 2 As shown, a blade body 10 is obtained, which includes a root portion 11 corresponding to the blade root 110 of the blade structure 100 of the blade 30, a petiole portion 12 corresponding to the petiole 120 of the blade structure 100 of the blade 30, and an airfoil body portion 13 corresponding to the airfoil body 130 of the blade structure 100 of the blade 30. The airfoil body portion extends between the petiole portion 12 and an airfoil body tip 15 (corresponding to the tip 135 of the airfoil body 130 of the blade structure 100 of the blade 30). The airfoil body portion 13 includes a leading edge portion 13a corresponding to the leading edge portion 136 of the airfoil body 130 of the blade structure 100 of the blade 30. The leading edge portion 13a is used to receive a metal strip to form the leading edge of the final blade.

[0041] After the production of the main blade body or in parallel with the production of the main blade body, a nearly finished leading edge (metal strip) having the shape and dimensions defined in the theoretical digital model of the leading edge is manufactured by additive manufacturing. Among the known methods of additive manufacturing, the leading edge can be obtained in particular by the following methods:

[0042] - a multi-layer metal additive manufacturing process by using a laser source to bond particles together by fusion, also known as powder bed additive manufacturing or SLM (selective laser melting) or LBM (laser beam melting),

[0043] -Laser Metal Deposition (LMD),

[0044] -Multi-layer metal additive manufacturing, by fusing particles using an electron beam – “electron beam melting”.

[0045] After additive manufacturing, the leading edge is obtained, already having the shape (external geometry) and the desired final dimensions (the "net-shape" part). This eliminates the need for machining the leading edge's outer wall and appropriate mechanical polishing operations, which are typically performed when the leading edge is obtained by casting and are complex to perform due to the part's flexibility. These finishing operations can be replaced by surface treatments, such as electrochemical polishing, which do not affect the leading edge's dimensions.

[0046] This provides a finished leading edge or metal strip 200 ready for assembly to the blade body 10, e.g. Figure 2 The leading edge 200 comprises an inner wall 201 intended to be joined to the leading edge portion 13a of the blade body 10 and an outer wall 202 defining the leading edge profile of the final blade. The leading edge 200 also comprises a nose 203 from which two wings 204 and 205 extend.

[0047] In the present invention, leading edge 200 includes a first portion 210 made of a first metallic material. First portion 210 extends from lower end 206 of the leading edge to an intermediate position 207 between lower end 206 and upper end 208 of the leading edge. Leading edge 200 also includes a second portion 220 made of a second metallic material. Second portion 220 extends from intermediate position 207 to upper end 208 of the leading edge. Through additive manufacturing, the leading edge can be manufactured from several different metallic materials.

[0048] The first portion 210 is arranged along the longitudinal direction D L At height H 210 Upper extension, height H 210 Corresponding to the total airflow height H starting from the lower end 206 of the leading edge TOT200 By definition, the minimum radial height of the leading edge, 0%, corresponds to the intersection of the leading edge of the blade and the disk on which it is mounted, which internally defines the airflow path through the fan. Similarly, the maximum radial height of 100% corresponds to the radial highest point of the leading edge line.

[0049] The first portion 210 is intended to extend to an area of ​​the blade or to the airflow height (or leading edge height) where a foreign object strike (particularly a bird strike) is not significant because it only causes slight deformation of the leading edge. Therefore, the first portion 210 may be formed of a first metallic material having an average density.

[0050] The second portion 220 is arranged along the longitudinal direction D L At height H 220 Upper extension, height H 220 Corresponding to the total airflow height H starting from the middle position 207 TOT200 70% of the total airflow height. Unlike the first portion 210, the second portion 220 is intended to extend to the area below the blade or airflow height where foreign object impacts such as bird strikes are critical. For example, for a fan blade, large bird ingestion is critical at approximately 50% of the total airflow height, while ordinary bird ingestion is critical at approximately 85% of the total airflow height. Therefore, the second portion 220 is made of a second metal material having a density greater than that of the first metal material. As a non-limiting example:

[0051] The first metal material may be steel or titanium, while the second metal material is a nickel alloy, e.g. 718, or cobalt alloy;

[0052] The first metallic material may be titanium and the second metallic material may be steel.

[0053] The final step in blade manufacturing is to bond the metal leading edge 200 to the blade body 10 using a composite material. More specifically, Figure 2 As shown, the leading edge 200 is butted against the leading edge portion 13a of the airfoil portion 13 of the blade body 10, with a layer of adhesive or adhesive material 40 interposed between the inner wall 201 of the leading edge and the leading edge portion 13a of the blade body 10. The adhesive layer between the leading edge and the leading edge portion of the blade body can be applied in different ways. In particular, it can correspond to an adhesive material sandwiched between the inner wall of the leading edge and the leading edge portion of the blade body; after the entire assembly is completed, it is placed in a bonding mold, which is heated to activate (cure) the adhesive properties of the material. The adhesive layer can also be deposited directly on the inner wall 201 of the leading edge 200 and / or the leading edge portion 13a of the blade body, and assembled in a bonding mold capable of applying pressure to the elements to be assembled, and optionally a bonding heat treatment can be performed. Document US 2015 / 151485 describes in particular a method for bonding a leading edge to a composite blade body.

[0054] The resulting blade has excellent impact resistance in the area to be reinforced, preventing the ingestion of foreign matter, while not significantly affecting the overall weight of the blade, given the presence of the less dense section. This also avoids increasing the static stresses caused by centrifugal forces in the petiole, an area of ​​concentrated force in composite blade structures.

[0055] Figure 3 The blade 50 shown is different from the blade 30 described above in that the area of ​​the leading edge where the dense material portion extends is reduced at the upper end of the leading edge. More specifically, Figure 3 The blade 50 shown in FIG. 5 comprises a composite blade structure 300 having a longitudinal direction D L The blade root 310, the petiole 320 and the transverse direction D between the leading edge 400 and the trailing edge 332 T Extended airfoil body 330. Airfoil body 330 also includes a lower surface 333, an upper surface 334, and a tip 335. Leading edge 400 is comprised of a metal strip bonded to a leading edge portion 336 of airfoil body 330. With the exception of leading edge 400, blade 50 is made of a composite material.

[0056] The manufacture of the blade body and the metal strip added thereto to form the trailing edge of the final blade is the same as previously described for blade 30 and for reasons of simplicity will not be described further. Briefly noted, the leading edge comprises three portions of different density.

[0057] According to the present invention, the leading edge 400 includes a first portion 410 made of a first metal material. The first portion 410 extends from the lower end 406 of the leading edge to a first intermediate position 407 located between the lower end 406 and the upper end 409 of the leading edge. The leading edge 400 includes a second portion 420 made of a second metal material. The second portion 420 extends from the first intermediate position 407 to a second intermediate position 408 located between the lower end 406 and the upper end 409 of the leading edge, the second intermediate position being in the longitudinal direction D L The leading edge 400 further comprises a third portion 430 made of a third metal material. The third portion 430 extends from the second intermediate position 408 to the upper end 409 of the leading edge 400. By additive manufacturing, the leading edge can be made of several different metal materials.

[0058] The first portion 410 is arranged along the longitudinal direction D L At height H 410 Upper extension, height H 410 Corresponding to the total airflow height H starting from the lower end 406 of the leading edge TOT400 The third portion 430 is at a height H 430 Upper extension, height H 430 Corresponding to the total airflow height H starting from the second intermediate position 408 TOT400 The first and second portions are intended to extend to the lower region of the blade or to the airflow height where foreign object impacts, such as bird strikes, are less significant. Therefore, the first portion 410 and the third portion 430 can be formed of a first material and a third material, respectively, of average density. The first and third metal materials can be the same or different.

[0059] The second portion 420 is arranged along the longitudinal direction D L At height H 420 Upper extension, height H 420 Corresponding to the total airflow height H starting from the first intermediate position 407 TOT400 The third portion 420 is designed to extend to areas or airflow heights where foreign object impacts such as bird strikes are critical. Therefore, the second portion 220 is made of a second metal material having a density greater than that of the first or third materials. As a non-limiting example:

[0060] - The first and third metal materials may be steel or titanium, while the second metal material is a nickel alloy, e.g. 718, or cobalt alloy;

[0061] - The first and third metallic materials may be titanium, while the second metallic material is steel.

[0062] This embodiment allows further saving of the overall weight of the blade by the presence of two less dense portions.

Claims

1. A method for manufacturing a composite blade having an attached metal leading edge for a gas turbine aircraft engine, the method comprising: producing a composite blade body longitudinally comprising a root portion, a petiole portion, and an airfoil body portion, the airfoil body portion extending longitudinally between the petiole portion and the airfoil body tip and extending transversely between a leading edge portion and a trailing edge portion; manufacturing, by additive manufacturing, an additional metal leading edge extending longitudinally between a lower end of a petiole portion of the composite blade body and an upper end at a tip end of the airfoil body portion; bonding the manufactured additional metal leading edge to the leading edge-most portion of the airfoil body of the composite blade body, It is characterized in that the additional metal leading edge includes a first portion of a first metal material, the first portion extends from the lower end of the additional metal leading edge to a middle position between the lower end and the upper end of the additional metal leading edge, and a second portion of a second metal material, the second portion extends from the middle position to the upper end of the additional metal leading edge, and the density of the second metal material is greater than that of the first metal material, so that the additional metal leading edge has the maximum stiffness at the upper part of the blade.

2. The method according to claim 1, wherein The first portion extends longitudinally at a height corresponding to 30% of the total airflow height, and the second portion extends longitudinally at a height corresponding to 70% of the total airflow height.

3. The method according to claim 1 or 2, wherein: The first metal material is steel or titanium, and the second metal material is nickel or cobalt alloy.

4. The method according to claim 1 or 2, wherein: The first metal material is titanium, and the second metal material is steel.

5. A composite blade with an additional metal leading edge for a gas turbine aircraft engine, the blade comprising a composite blade structure, the blade structure longitudinally comprising a blade root, a blade stalk and an airfoil body, the airfoil body extending longitudinally between the blade stalk and the blade tip, and extending transversely between the leading edge portion and the trailing edge, the additional metal leading edge obtained by additive manufacturing being bonded to the leading edge portion of the airfoil body of the composite blade structure, the additional metal leading edge obtained by additive manufacturing extending longitudinally between a lower end of the blade stalk of the composite blade structure and an upper end at the blade tip of the blade structure, characterized in that The additional metal leading edge includes a first portion of a first metal material, the first portion extending from the lower end of the additional metal leading edge to a middle position between the lower end and the upper end of the additional metal leading edge, and a second portion of a second metal material, the second portion extending from the middle position to the upper end of the additional metal leading edge, the density of the second metal material being greater than that of the first metal material, so that the additional metal leading edge has the maximum stiffness at the upper part of the blade.

6. The blade according to claim 5, wherein: The first portion extends longitudinally at a height corresponding to 30% of the total airflow height, and the second portion extends longitudinally at a height corresponding to 70% of the total airflow height.

Images