A fan blade made of a composite material including a metal reinforcement and a method for manufacturing such a fan blade

Abstract

The present invention relates to a method for manufacturing a blade (100) made of composite material, in particular for a turbine of an aircraft, comprising the following steps: - injecting a resin to impregnate a fiber preform woven in three dimensions, - polymerizing the resin to form the blade (100), the blade comprising an airfoil (102), one longitudinal end of the airfoil being connected to a platform (112, 114), the platform comprising: a pressure part (116) and a suction part (118), the pressure part and the suction part being connected to the airfoil by a fillet (120); and a crack part (122) formed in the fiber preform between the pressure part and the suction part; strengthening the leading edge of the airfoil; strengthening the fillet by integrating metal reinforcements (126) on at least a part of the pressure part and the suction part of the platform and in the crack part.

Description

Technical Field

[0001] The present invention relates to the field of fan blades made of composite materials, particularly for turbines used in aircraft, and more specifically to an improvement in the mechanical strength of such composite fan blades. Background Art

[0002] The prior art particularly includes the documents WO2013 / 060977A2, FR3079445A1, WO2018 / 158544A1, and US2013 / 052030A1.

[0003] It is well known that outlet guide vanes (OGVs) are used in the aviation field. An OGV is a fixed vane device whose function is to rectify the air flow at the outlet of the fan blades to form the secondary flow of the turbine.

[0004] The OGVs form rows of fixed vanes that allow the air flow passing through the turbine to be guided at an appropriate speed and angle.

[0005] Generally, in the present application, the terms "upstream" and "downstream" are defined in relation to the direction of the air flow in the turbine. In addition, generally, in the present application, the terms "inner" and "outer" or "internal" and "external" are defined radially with respect to the axis of the turbine.

[0006] The OGV can be made of metal or composite materials, particularly to reduce its mass.

[0007] Currently, composite OGVs are produced by injecting epoxy resin (e.g., by resin transfer molding (RTM)) into three-dimensional (3D) woven carbon fiber preforms.

[0008] Figure 1 An OGV 10 is shown. The OGV includes a vane 12 that has a pressure surface 18 and a suction surface 28, which extend between a leading edge 14 and a trailing edge 16. The longitudinal ends of the vane are connected to the following platforms: an inter-OGV platform 20 mounted at the radially outer end of the vane and disposed between the OGV and adjacent OGVs, and a platform 22 mounted at the radially inner end of the vane and connected to the hub 24 of the rectifier.

[0009] A metal reinforcement 26 in the form of a metal foil, such as nickel cobalt, is co-injected into the leading edge portion 14 of the vane 12.

[0010] Since composite materials are sensitive to certain mechanical constraints, the metal reinforcement helps to prevent erosion and potential impacts on the OGV.

[0011] It is also well known that a composite OGV has a hybrid structure having a carbon material weave for generating an aerodynamic region and a thermoplastic resin (with or without fillers) forming the core of the OGV.

[0012] However, the mechanical properties of such an OGV are weaker than those of traditional armor.

[0013] In addition, the thermoplastic resin only fills the cavity between the attachment platforms for the fan blades and thus does not allow restricting the openings of the platforms, which would reduce the mechanical constraints on the OGV.

[0014] Studies have been conducted to analyze the mechanical strength of this OGV. According to the results of the finite element model, at the fillet (shown as dashed lines A, B, and C respectively in Figure 2 , Figure 3 and Figure 4 ), that is, at the connection positions between the platforms 20, 22 and the blade 12, a systematic concentration of constraints was found.

[0015] Tensile, compression, and bending tests have also been carried out on these components. The calculated results show the same failure regions as those found by expert tests.

[0016] Therefore, there is a need for an OGV that can reduce the constraints in these failure regions and better distribute the forces.

[0017] The object of the present invention is to propose a solution that can remedy at least some of these drawbacks. Summary of the Invention

[0018] The present invention allows restricting the openings of the platforms of the fan blades made of composite materials for a turbine to reduce the constraints at the connection fillets (critical regions) between the blades and the platforms.

[0019] To this end, the present invention relates to a manufacturing method of a stator fan blade made of composite materials, especially for a turbine of an aircraft, comprising the following steps:

[0020] - Weaving fibers in three dimensions to produce a fiber preform,

[0021] - Installing the fiber preform in a mold,

[0022] - Injecting resin into the mold to impregnate the fiber preform,

[0023] - Aggregate resin to form a fan blade, the fan blade including a blade having a pressure side and a suction side that extend between a leading edge and a trailing edge, and longitudinal ends of the blade being connected to a platform that includes: a pressure section and a suction section, the pressure section and the suction section being connected to the blade by a connecting fillet; and a cracking portion formed in the fiber preform between the pressure section and the suction section of the platform,

[0024] - Strengthen the leading edge of the blade by integrating a first metal reinforcement on the leading edge of the blade,

[0025] Characterized in that the method further comprises the steps of:

[0026] - Strengthen the connecting fillet by integrating a second metal reinforcement on at least a portion of the pressure section and the suction section of the platform and in the cracking portion.

[0027] According to one embodiment, the step of adding the second metal reinforcement includes bonding the second metal reinforcement to at least a portion of the pressure section and the suction section of the platform and to the cracking portion.

[0028] According to another embodiment, the step of adding the second metal reinforcement includes co-injecting the second metal reinforcement onto at least a portion of the pressure section and the suction section of the platform and into the cracking portion.

[0029] The invention also relates to a composite fan blade, in particular for a turbine of an aircraft, the fan blade being produced by the manufacturing method according to the invention. Thus, the fan blade includes a second metal reinforcement disposed on at least a portion of the pressure section and the suction section of the platform and disposed in the cracking portion.

[0030] Advantageously, the invention makes it possible to reduce the constraints in the connecting fillet (i.e., the critical area) between the blade and the platform to ensure mechanical robustness.

[0031] Advantageously, the second metal reinforcement allows to be used as a connecting member between the pressure section and the suction section of the platform, thereby making it possible to strengthen the critical area. In the case of co-injection, this metal reinforcement significantly improves the correct formation of the OGV radius, especially compared to a carbon braid, which is not rigid and does not have an exact cavity shape.

[0032] Advantageously, the second metal reinforcement allows to limit the opening of the pressure section and the suction section of the platform by reducing the constraints at the position of the connecting fillet under the action of tensile, compressive and bending stresses. In addition, the second metal reinforcement allows to withstand the forces of the connecting fillet, especially in the case of compression, and these forces will be distributed over the entire base of the platform, thereby increasing the critical buckling force.

[0033] According to one embodiment, the second metal reinforcement has a dimension along the longitudinal direction between the leading edge and the trailing edge, which is substantially equal to the dimension of the platform in the longitudinal direction of the pressure side and the suction side of the blade. In other words, the second metal reinforcement extends along the entire length of the platform.

[0034] According to another embodiment, the second metal reinforcement comprises two parts, and each part of the second metal reinforcement has a dimension along the longitudinal direction between the leading edge and the trailing edge, which is between 15% and 35% of the chord length at the longitudinal end of the blade before the connecting fillet, in the longitudinal direction of the pressure side and the suction side of the blade. In other words, the second metal reinforcement only extends along a part of the length of the platform.

[0035] Advantageously, this allows for a reduction in the mass of the fan blade of the rectifier, especially by lightening the second metal reinforcement.

[0036] The dimension of the second metal reinforcement along the longitudinal direction of the blade can be between 30% and 70% of the dimension of the platform in this direction. In other words, the thickness of the second metal reinforcement is between 30% and 70% of the thickness of the platform.

[0037] Preferably, the dimension of the second metal reinforcement along the longitudinal direction of the blade is substantially equal to 50% of the dimension of the platform in this direction.

[0038] The dimension of the second metal reinforcement along the direction perpendicular to the longitudinal direction of the blade and perpendicular to the longitudinal direction of the pressure side and the suction side of the blade, between the leading edge and the trailing edge, can be at least equal to the dimension of the platform in this direction. In other words, the width of the second metal reinforcement is at least equal to the width of the platform.

[0039] In one embodiment, the platform is a platform that is radially located inside the rectifier relative to the axis of the rectifier. In this embodiment, the second metal reinforcement includes a protrusion that extends perpendicularly to the platform at the longitudinal end facing the trailing edge of the blade. This protrusion allows the second metal reinforcement to have a tapered bearing function.

[0040] In one embodiment, the second metal reinforcement is made of titanium. Preferably, the second metal reinforcement is made of a metal material that is compatible with the composite material of the fan blade of the rectifier (i.e., a material that has no incompatibility with the composite material).

[0041] The present invention also relates to a composite fan blade for a ducted fan, especially for an aircraft, which is known by the abbreviation "propfan" or "open rotor", and the fan blade is produced by the manufacturing method according to the present invention. Description of the Drawings

[0042] The present invention will be better understood from the following description, given by way of non-limiting example and with reference to the accompanying drawings, in which:

[0043] Figure 1 already described Figure 1 shows an OGV according to the prior art,

[0044] Figure 2 already described Figure 2 shows the upstream suction / pressure lower part of an OGV according to the prior art,

[0045] Figure 3 already described Figure 3 shows the downstream suction / pressure lower part of an OGV according to the prior art,

[0046] Figure 4 already described Figure 4 shows the downstream suction / pressure upper part of an OGV according to the prior art,

[0047] Figure 5 Figure 5 shows the lower part of a fan blade according to an embodiment of the present invention,

[0048] Figure 6 Figure 6 shows the upper part of a fan blade according to an embodiment of the present invention,

[0049] Figure 7 Figure 7 shows the lower part of a fan blade according to another embodiment of the present invention,

[0050] Figure 8 Figure 8 shows the lower part of a fan blade according to yet another embodiment of the present invention, and

[0051] Figure 9 Figure 9 is a flowchart of a method for manufacturing a fan blade according to the present invention.

[0052] Elements having the same function in different embodiments have the same reference numerals in the figures. DETAILED DESCRIPTION

[0053] Figures 5 to 8 Shows a fan blade 100 made of composite material for an aircraft turbine, such as an OGV. The present invention also applies to fan blades made of composite material for a ducted fan, in particular for an aircraft, the ducted fan being known by the acronym "propfan" or "open rotor".​​​​​​​​​​​​​​

[0054] The fan blade 100 according to the present invention, and more precisely the blade 102, is produced from a fiber preform (such as a preform of carbon fiber) resulting from three-dimensional (3D) weaving. The preform is woven as a single piece. The preform is then molded using a resin (such as an epoxy resin).

[0055] The fan blade 100 includes a blade 102 having an elongated aerodynamic profile, the blade 102 having a pressure side 104 and a suction side 106, the pressure side 104 and the suction side 106 extending between a leading edge 108 and a trailing edge 110 opposite the leading edge. In other words, the blade 102 is laterally delimited by the pressure side 104 and the suction side 106 connecting the leading edge 108 and the trailing edge 110. The leading edge 108 is arranged upstream of the direction of flow of the gas in the turbine. The pressure side 104 and the suction side 106 are curved surfaces (concave and convex respectively). The blade 102 extends longitudinally along an axis X, as Figures 5 to 8 shown.

[0056] A first longitudinal end of the blade 102 is connected to a first platform 112, and a second longitudinal end of the blade 102 is connected to a second platform 114. For example, in Figure 5 , Figure 7 and Figure 8 , the lower longitudinal end of the blade 102 is connected to a radially inner platform 112, and in Figure 6 , the upper longitudinal end of the blade 102 is connected to a radially outer platform 114. In other words, the blade 102 is radially delimited between the inner platform 112 and the outer platform 114. The platforms 112, 114 extend perpendicular to the longitudinal direction of the blade 102 (i.e., the axis X). As Figures 5 to 8 shown, the platforms 112, 114 extend between the leading edge 108 and the trailing edge 110 along a longitudinal direction (represented by an axis Y) longitudinal to the pressure side 104 and the suction side 106 of the blade 102, the axis Y being called the longitudinal direction of the platform, and the platforms 112, 114 extend along a direction (represented by an axis Z) perpendicular to the longitudinal direction of the blade 102 (axis X) and the longitudinal direction of the platform (axis Y), the axis Z being called the radial direction or width of the platform.

[0057] Each platform 112, 114 includes a pressure section 116 and a suction section 118. The pressure section 116 and the suction section 118 are connected to the blade 102 by a connecting fillet 120. In particular, in the fiber preform forming the fan blade, a crack 122 is formed between the pressure section 116 and the suction section 118 of the platforms 112, 114.

[0058] The blade 100 further includes a metal reinforcement 124 in the form of a metal foil, and the metal reinforcement 124 is mounted on the leading edge 108 of the blade 102. The metal reinforcement 124 can be made of nickel-cobalt or any other metal material compatible with the composite material of the blade 100. Advantageously, the metal reinforcement 124 enables the mechanical strength of the blade 100 to be improved.

[0059] As Figure 5 shown, the blade 100 further includes a metal reinforcement 126, and the metal reinforcement 126 is disposed on at least one part of the pressure side 116 and the suction side 118 of the platform 112 and is disposed in the cracking part 122. The metal reinforcement 126 allows the connection between the blade 102 and the platform 112 to be strengthened, thereby reducing the constraint in the connection fillet 120, and further enabling the mechanical strength of the blade 100 to be improved.

[0060] As Figure 6 shown, the blade 100 further includes a metal reinforcement 128, and the metal reinforcement 128 is disposed on at least a part of the pressure side 116 and the suction side 118 of the platform 114 and is disposed in the cracking part 122. Similar to the metal reinforcement 126, the metal reinforcement 128 allows the connection between the blade 102 and the platform 114 to be strengthened, thereby reducing the constraint in the connection fillet 120, and further enabling the mechanical robustness of the blade 100 to be improved.

[0061] The metal reinforcements 126 and 128 can be made of titanium or any other metal material compatible with the composite material of the blade 100.

[0062] The metal reinforcements 126 and 128 extend along the longitudinal direction (axis Y) and the radial direction (axis Z) of the platform.

[0063] The metal reinforcement 128 can extend along the entire length lp (axis Y) of the platforms 112 and 114. In this case, the dimension of the metal reinforcement 128 along the longitudinal direction (axis Y) of the platform is substantially equal to the length lp of the platforms 112 and 114.

[0064] Alternatively, as Figure 7 shown, in order to reduce the mass of the blade 100, the metal reinforcement 128 can only extend along a part of the length (axis Y) of the platforms 112 and 114. In this case, the metal reinforcement can include a first part 130 and a second part 132. The dimension of each part 130 and 132 of the metal reinforcement along the longitudinal direction (axis Y) of the platform is between 15% and 35% of the chord length C at the longitudinal end of the blade 102 before the connection fillet 120. The chord length C corresponds to the dimension of the blade 102 along the pressure surface or the suction surface between the leading edge and the trailing edge at one end position of the blade 102 near the connection fillet 120. AsFigure 7 As shown, the length lr1 of part 130 of the metal reinforcement is between 15% and 35% of the chord length C, and the length lr2 of part 132 of the metal reinforcement is between 15% and 35% of the chord length C. The sum of the lengths lr1 and lr2 of parts 130 and 132 of the metal reinforcement is less than the length lp of the platform 112. Here, the length of the chord length C is greater than the length lp of the platform 112.

[0065] As Figure 6 shown, the dimension of the metal reinforcement 128 along the longitudinal direction (axis X) of the blade 102, i.e., the thickness er of the metal reinforcement 128, depends on the load condition and can be between 30% and 70% of the thickness ep of the platform 114, preferably about 50% of the thickness ep of the platform 114.

[0066] The radial dimension Lr (axis Z) of the metal reinforcement 128, i.e., the width, can be at least equal to the radial dimension of the platform 114. Thus, the metal reinforcement 128 covers the entire base of the platforms 112 and 114 and extends to the crack part 122. Thus, the metal reinforcement covers at least the entire contour of the platforms 112 and 114.

[0067] As Figure 8 shown, the metal reinforcement 128 includes a protrusion 134 at the longitudinal end facing the trailing edge 110 of the blade 102, and the protrusion 134 extends perpendicular to the platform 112. The protrusion 134 has a conical bearing function. Thus, the metal reinforcement 128 can place the fan blade 100 in a conical bearing.

[0068] The manufacturing method of the above fan blade is as Figure 9 shown. The manufacturing method includes step S10: weaving fibers in 3D to produce a fiber preform, followed by step S20: installing the fiber preform in a mold, then step S30: injecting resin into the mold to impregnate the fiber preform, and finally step S40: polymerizing the resin to form the fan blade.

[0069] To improve the mechanical robustness of the fan blade 100, the manufacturing method includes step S50: strengthening the leading edge 108 of the blade 102 by integrating a metal reinforcement 124 on the leading edge 108 of the blade 102. The metal reinforcement 124 can be co-injected into the leading edge 108 of the blade 102. Alternatively, the metal reinforcement 124 can be bonded to the leading edge 108 of the blade 102.

[0070] To reduce the constraints at the position of the fillet 120 connecting the blade 102 and the platforms 112, 114 of the fan blade 100 made of composite material, the manufacturing method includes step S60: strengthening the fillet 120 by integrating second metal reinforcements 126, 128, 130, 132 on at least a part of the pressure side 116 and the suction side 118 of the platforms 112, 114 and in the cracking portion 122. The metal reinforcements 126, 128 can be co-injected into at least one part of the pressure side 116 and the suction side 118 of the platforms 112, 114 and co-injected into the cracking portion 122. Alternatively, the metal reinforcements 126, 128 can be bonded to at least a part of the pressure side 116 and the suction side 118 of the platforms 112, 114 and bonded to the cracking portion 122.

Claims

1. A manufacturing method of a blade (100) made of composite material for a turbine, comprising the following steps: - Weaving (S10) fibers in three dimensions to produce a fiber preform, - Installing (S20) the fiber preform in a mold, - Injecting (S30) resin into the mold to impregnate the fiber preform, - Polymerizing (S40) the resin to form the blade (100), the blade including a blade (102) having a pressure surface (104) and a suction surface (106), the pressure surface and the suction surface extending between a leading edge (108) and a trailing edge (110), longitudinal ends of the blade being connected to platforms (112, 114), the platforms including: a pressure section (116) and a suction section (118), the pressure section and the suction section being connected to the blade through a connecting fillet (120); and a crack portion (122) formed in the fiber preform between the pressure section and the suction section of the platform, - Strengthening (S50) the leading edge of the blade by integrating a first metal reinforcement (124) on the leading edge of the blade, characterized in that the method further comprises the following steps: - Strengthening (S60) the connecting fillet by integrating second metal reinforcements (126, 128, 130, 132) on at least a part of the pressure section and the suction section of the platform and in the crack portion.

2. The manufacturing method according to claim 1, wherein The step of adding the second metal reinforcements (126, 128, 130, 132) includes bonding the second metal reinforcements to at least a part of the pressure section (116) and the suction section (118) of the platform and bonding them into the crack portion (122).

3. The manufacturing method according to claim 1, wherein, The step of adding the second metal reinforcements (126, 128, 130, 132) includes co-injecting the second metal reinforcements onto at least a part of the pressure section (116) and the suction section (118) of the platform and co-injecting them into the crack portion (122).

4. The manufacturing method according to claim 1, wherein, The turbine is for an aircraft.

5. A blade (100) made of composite material for a turbine, the blade being produced by the manufacturing method according to any one of claims 1 to 4.

6. The fan blade (100) made of a composite material according to claim 5, wherein, The second metal reinforcements (126, 128) have a dimension along a first longitudinal direction (Y) longitudinal to the pressure surface (104) and the suction surface (106) of the blade (102) between the leading edge (108) and the trailing edge (110) equal to the dimension (lp) of the platform (112, 114) in the first longitudinal direction.

7. The blade (100) made of a composite material according to claim 5, wherein, The second metal reinforcement includes two parts, and each part of the second metal reinforcement has a dimension (lr1, lr2) along a first longitudinal direction (Y) longitudinal to the pressure surface (104) and the suction surface (106) of the blade (102) between the leading edge (108) and the trailing edge (110) between 15% and 35% of the chord length (C) at the longitudinal end of the blade before the connecting fillet (120).

8. The fan blade (100) made of a composite material according to any one of claims 5 to 7, wherein, The dimension (er) of the second metal reinforcement (126, 128, 130, 132) along the second longitudinal direction (X) of the blade (102) is between 30% and 70% of the dimension (ep) of the platform (112, 114) in the second longitudinal direction.

9. The fan blade (100) made of a composite material according to any one of claims 5 to 7, wherein, The dimension (Lr) of the second metal reinforcement (126, 128, 130, 132) in a third direction between the leading edge (108) and the trailing edge (110) along a first longitudinal direction (Y) perpendicular to the second longitudinal direction (X) of the blade (102) and perpendicular to the pressure surface (104) and the suction surface (106) of the blade is at least equal to the dimension of the platform (112, 114) in the third direction.

10. The fan blade (100) made of a composite material according to any one of claims 5 to 7, wherein, The platform (112) is a platform that is radially located inside the stator vane relative to the axis of the stator vane. Among them, the second metal reinforcement (128) includes a protrusion (134) that extends perpendicular to the platform at the longitudinal end facing the trailing edge (110) of the blade (102).

11. The fan blade (100) made of a composite material according to any one of claims 5 to 7, wherein, The second metal reinforcement (126, 128, 130, 132) is made of titanium.

12. A vane of a ducted fan made of a composite material, the vane being produced by the manufacturing method according to any one of the preceding claims 1 to 3.

13. The vane according to claim 12, wherein the ducted fan is used for an aircraft.

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