Method for improving the mechanical performance of blower blades and associated blades

Abstract

This fan blade (5) for an aeronautical turbomachine includes a blade root (2) and a blade (3). The blade root (2) has at least one recess (6) relative to a surface (7) of the blade root, allowing for an increase in the minimum radius of a fillet (8) between said blade root (2) and said blade (3). At least one recess (6) is filled with a filler piece of complementary shape, designed to restore the continuity of the surface (7) of the blade root (2). Figure for the abbreviation: [Fig 3]

Description

Title of the invention: Method for improving the mechanical performance of fan blades and associated blade Technical field

[0001] The invention relates to the field of fan blades for aeronautical turbomachines. The invention also relates to fans and turbomachines equipped with these blades, as well as a method for improving the mechanical and acoustic performance of these blades. Previous techniques

[0002] The design of a fan blade involves several disciplines whose objectives are generally antagonistic. It must allow for optimal aerodynamic performance and guarantee the mechanical strength of the blade, while limiting the mass of the blade as well as its acoustic signature.

[0003] For example, optimizations of blade mass or propulsive efficiency tend to increase stresses in the blades.

[0004] Thus, the increase in mechanical stresses in the blades can cause a reduction in the mechanical strength of the blades, and therefore a reduction in their service life.

[0005] Peaks of mechanical stress are particularly encountered in the connection zones between the root and the blade of the vane. Statement of the invention

[0006] The aim of the invention is to propose a fan blade making it possible to reduce mechanical stresses, while ensuring good aerodynamic and acoustic performance.

[0007] The invention relates to a fan blade for an aeronautical turbomachine comprising a blade root and a blade blade. The blade root has at least one recess relative to a surface of the blade root making it possible to enlarge the minimum radius of a connection fillet between the blade root and the blade blade. In addition, at least one recess is filled with a filling piece. Such a configuration improves the mechanical performance of the blade, in particular by reducing the mechanical stresses in the connection fillet. In addition, by filling the recess, the filling piece tends to improve the acoustic performance of the blade.

[0008] For example, the recess is arranged near a leading edge and / or a trailing edge of the blade. Depending on the configurations, it is possible to provide recesses also opposite the intrados and / or the extrados of the blade.

[0009] Advantageously, the shape of the filling piece is complementary to the recess that it fills so as to restore the continuity of the surface of the blade root. Such filling makes it possible to restore the acoustic and aerodynamic performances of the blade that could have been degraded by the production of the recess. In a preferred embodiment, each recess is filled with a filling piece. In other embodiments, it remains possible to fill only part of the recesses.

[0010] According to an advantageous characteristic, the filling part comprises a material with a lower Young's modulus than that of the blade. Such a configuration tends to preserve the durability of the filling part 13, by avoiding high mechanical stresses within the filling part 13. Alternatively, it remains possible to have a filling part in the same material as that of the blade.

[0011] For example, the filling piece is glued to the blade root.

[0012] According to another aspect, the invention also relates to a fan for an aeronautical turbomachine having a blade as described above, as well as an aeronautical turbomachine comprising one or more of these fans.

[0013] According to another aspect, the invention also relates to a method for improving the mechanical and acoustic performance of a fan blade comprising a blade root and a blade blade. The method comprises a step of producing at least one recess relative to a surface of the blade root making it possible to enlarge the minimum radius of a connection fillet between the blade root and the blade blade. In addition, the method comprises a step of filling at least one recess using a complementary-shaped filling part intended to restore the continuity of the surface of the blade root.

[0014] For example, the filling step comprises a step of gluing the filling part to the blade root. Brief description of the drawings

[0015] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0016] [Fig.l] is a partial sectional view of a blade according to the prior art;

[0017] [Fig.2] is a partial sectional view of a blade according to the invention;

[0018] [Fig.3] is a partial perspective view of the dawn of [Fig.2];

[0019] [Fig.4] is a partial perspective view of the blade of Figures 2 and 3 with a filling piece in non-inserted position according to the invention; and

[0020] [Fig.5] is a flowchart of a process for improving mechanical performance caniques of a blade according to the invention; Detailed description of at least one embodiment

[0021] The invention will be described below in the context of its application to an aeronautical turbomachine fan blade. Such a blade can for example equip a rotor and / or a stator in unducted fan type configurations, also known by the acronym USF, for “Unducted Single Fan” in English.

[0022] The invention may also find an interesting application in the field of reduced models of such blades, used for example during wind tunnel tests. Indeed, such reduced-size models increase the risk of having unacceptable stress peaks, particularly in the connection zones between the root and the blade of the blade.

[0023] [Fig.l] illustrates a blade 1 according to the prior art. The blade 1 comprises a root 2 and a blade 3 connected to each other by a connection zone having a minimum radius RL. The blade root 2 is fixed by fixing means (not shown) to a support 4. For example, in the case of a fan rotor, the support 4 is rotatable and mounted radially on a propeller hub while being able to pivot about a radial axis of the rotor. The support 4 can also be fixed in the case of a rectifier.

[0024] Figures 2 and 3 illustrate a blade 5 according to the invention. In the figures, the same objects bear the same references. The root 2 has at least one recess 6 relative to a surface 7 of the root of the blade. The recess 6 of the surface 7 makes it possible to create a surface 10 of the root 2 further from the surface 9 of the blade and thus makes it possible to connect the root 2 and the blade 3 by a connection fillet 8 of minimum radius R2 greater than the minimum radius RI obtained in the absence of the recess 6.

[0025] Preferably, the fillet 8 is tangent to the surface 9 of the blade 3 and tangent to the surface 10 of the root 2. For example, the fillet 8 comprises a cylindrical surface which may be circular, elliptical or parabolic.

[0026] Such a recess 6 is preferably arranged near a leading edge 11 and / or a trailing edge 12 of the blade 3 of the vane 5. In the example illustrated in [Fig. 3], the recess 6 is arranged near the trailing edge 12 of the blade 3.

[0027] The presence of a recess 6 makes it possible to obtain a larger minimum radius R2 which tends to improve the mechanical performance. For example, for a given level of mechanical stress, the use of such a minimum radius R2 makes it possible to reduce the maximum values ​​of the mechanical stresses in the fillet 8. For example, the use of such a minimum radius R2 makes it possible to withstand greater stresses, with the same level of reliability.

[0028] However, although the use of such a recess 6 is particularly beneficial for mechanical performance, it risks deteriorating the aerodynamic profile of the blade 5. Indeed, the recess 6 risks creating a discontinuity in any gas flow vein passing nearby. In addition, the recess 6 can create an aero leak dynamic between the extrados and the intrados of the blade 5, reducing the aerodynamic performance of the blade 5. The recess 6 can also degrade the acoustic performance of the blade 5 by generating unwanted noise.

[0029] [Fig. 4] illustrates a preferred embodiment, in which the recess 6 is filled with a filling piece 13, illustrated here in the non-inserted position. The filling piece 13 is of a shape complementary to the recess 6 and is intended to restore the continuity of the surface 7 of the blade root 2. For example, in the inserted position the filling piece 13 substantially matches the volume of the recess 6.

[0030] In the case where the blade has several recesses 6, for example a first recess 6 near the leading edge 11 and a second recess 6 near the trailing edge 12, each recess 6 is filled with an associated filling piece 13. Each filling piece 13 is of a shape complementary to the associated recess 6.

[0031] The use of such filling pieces 13 makes it possible to restore the aerodynamic and acoustic performances of the blade 5, which could have been degraded by the production of the recesses 6.

[0032] Preferably, the filling part 13 comprises a material with a lower Young's modulus than that of the blade 5, so as to avoid high mechanical stresses within the filling part 13.

[0033] Each recess 6 is filled by inserting the associated filling piece 13 therein. In order to ensure that the filling piece 13 remains in place after insertion, it is possible to insert it by force and / or to glue it to the blade root 3, using an adhesive arranged between the complementary shaped surfaces of the blade root 2 and the filling piece 13.

[0034] A method for improving the mechanical performance of a blade 5 according to the invention will now be described with reference to [Fig. 5].

[0035] The method begins with a step 14 of producing at least one recess 6 relative to a surface 7 of the blade root 2 making it possible to enlarge the minimum radius R2 of a connection fillet 8 between the blade root 2 and the blade 3.

[0036] The method continues with a step 15 of filling at least one recess 6 using a filling piece 13 of complementary shape intended to restore the continuity of the surface 7 of the blade root 2. Preferably, the filling step 15 comprises a step of bonding the filling piece 13 to the blade root 2.

Claims

Claims

1. Fan blade (5) for an aeronautical turbomachine comprising a blade root (2) and a blade blade (3), characterized in that the blade root (2) has at least one recess (6) relative to a surface (7) of the blade root making it possible to enlarge the minimum radius (R2) of a connection fillet (8) between said blade root (2) and said blade blade (3) in which at least one recess (6) is filled with a filling piece (13).

2. A blade according to claim 1 wherein said recess (6) is arranged near a leading edge (11) and / or a trailing edge (12) of the blade (3).

3. Blade according to one of claims 1 or 2, in which the filling piece (13) has a shape complementary to the recess which it fills so as to restore the continuity of the surface (7) of the blade root (2).

4. A blade according to claim 3, wherein said filler piece (13) comprises a material with a lower Young's modulus than that of the blade (5).

5. Blade according to one of claims 3 or 4, in which the filling piece (13) is glued to the blade root (2).

6. Fan for an aeronautical turbomachine comprising at least one blade (5) according to one of claims 1 to 5.

7. Aeronautical turbomachine comprising at least one fan according to claim 6.

8. Method for improving the mechanical and acoustic performance of a fan blade comprising a blade root and a blade blade, characterized in that it comprises a step of producing at least one recess (6) relative to a surface (7) of the blade root (2) making it possible to enlarge the minimum radius (R2) of a connection fillet (8) between said blade root (2) and said blade blade (3) and a step of filling at least one recess (6) using a filling part (13) of complementary shape so as to restore the continuity of the surface (7) of the blade root (2).

9. Method according to claim 8 in which the filling step comprises a step of gluing said filling part (13) to the blade root (2).

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