ROTOR BLADE FOR A TURBOMACHINE

Abstract

The invention relates to a rotor blade for a turbomachine, comprising a blade connected to a base (5), the blade being made of composite material and formed by a fibrous preform embedded in a resin, the blade comprising an upper and lower surface connected by a leading edge and a trailing edge of the blade, the base (5) being made of metallic material and formed by an outer portion (54) of a spar which also comprises an inner portion (52), this inner portion (52) being engaged in the preform of the blade and comprising an upper surface face (522) and an upper surface face (524), wherein the inner portion (52) comprises at least one recess (50, 50a, 50b) formed on at least one of its upper and lower surfaces (522, 524), the at least one recess being completely filled. Figure for the abstract: Figure 6

Description

Title of the invention: ROTOR BLADE FOR A TURBOMACHINE Technical field

[0001] The invention relates to the field of turbomachines, in particular aircraft turbomachines. More particularly, the invention relates to a rotor blade for a turbomachine which comprises in particular a blade made of composite material and a root made of metallic material. Technical background

[0002] In a known manner and assuming a ducted architecture, a turbomachine, in particular a double-flow turbomachine, of an aircraft comprises, from upstream to downstream in the direction of gas flow, a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine. The rotor of the low-pressure compressor is driven by the rotor of the low-pressure turbine. The rotor of the high-pressure compressor is driven by the rotor of the high-pressure turbine.

[0003] The turbomachine comprises rotor blades rotating about a longitudinal axis of the turbomachine. These rotor blades can rotate inside casings. This is for example the case of the rotor blades of the fan which are surrounded by a retention casing.

[0004] Such a rotor blade comprises a blade formed with an extrados (or convex outer surface) and with a intrados (or concave inner surface), connected together at their upstream ends by a leading edge and at their downstream ends by a trailing edge. The blade is made of composite material to reduce the mass while having good mechanical properties. For example, the blade is made by injecting a resin, for example by liquid resin injection molding (RTM, acronym for the English expression "Resin Transfer Molding") into a fiber preform, formed for example of fibers woven in three dimensions (3D) or in multilayers.

[0005] The rotor blade also includes a root which can be connected to the blade generally by gluing.

[0006] Figures 1 and 2 illustrate an example of such a blade root 5 which comprises a first end 52 forming a spar which extends at least partly into the blade. The spar comprises a lower surface face 522 located on the lower surface side of the blade and an upper surface face 524 located on the upper surface side of the blade. The root 5 comprises a second end 54 opposite the first end 52 and forming an attachment of cylindrical geometry. This attachment of the blade root 5 is intended to be mounted on a rotor disc.

[0007] The root is made of metallic material. Thus, the weight of the blade root represents a very significant percentage of the overall mass of the rotor blade. With reference to FIGS. 1 and 2, the blade root 5 can be lightened by integrating a cavity 520 from the top, at the first end 52, for example by machining. This cavity 520 extends between the intrados 522 and extrados 524 faces. However, the machining of this cavity in the metal blade root can be complex to carry out. Indeed, the machining tooling can have difficulty accessing the spar of the root and thus limits the creation of such a cavity.

[0008] Furthermore, it is necessary that the contact surface between the composite material blade and the metal material blade root be as large as possible to obtain a good connection between these two elements (namely the blade and the root spar).

[0009] In this context, it is interesting to propose a solution making it possible to overcome at least one of the aforementioned drawbacks, in particular by optimizing and simplifying the integration of a metal foot in a composite material blade of a rotor blade. Summary of the invention

[0010] The present invention provides a simple, effective and economical solution to the aforementioned drawbacks of the prior art.

[0011] For this purpose, the invention relates to a rotor blade for a turbomachine, in particular an aircraft, the blade extending along an axis of elongation A and comprising a blade connected to a root, the blade being made of composite material and being formed by a fiber preform embedded in a resin, the blade comprising a lower surface and an upper surface connected to each other by a leading edge and a trailing edge of the blade, the root being made of metallic material and formed by an external part of a spar which also comprises an internal part, this internal part being engaged in the preform of the blade and comprising an intrados face located on the side of the intrados of the blade and an extrados face located on the side of the extrados of the blade.

[0012] According to the invention, the internal part of the spar comprises at least one recess provided on at least one of its intrados and extrados faces, said at least one recess being entirely filled.

[0013] Thus, this solution makes it possible to achieve the aforementioned objective. In general, the rotor blade of the invention has both a simplified and reinforced integration between the root made of metallic material and the blade made of composite material and a reduced overall mass.

[0014] Indeed, the presence of one or more recesses on the intrados face and / or the face extrados of the internal part of the spar makes it possible to increase the adhesion surface (for example by gluing) at the interface between the internal part of the spar and the blade. In this way, the blade of the invention makes it possible to ensure strong retention of the blade by the internal part of the spar, for example in the event of detachment of this blade during operation.

[0015] Furthermore, the recess makes it possible to form so-called acute angles (in particular less than 90°) making it possible to generate a robust mechanical connection between the blade and the internal part of the spar thanks to multiple points of force transmission, in particular by complementarity of shape of the entirely filled recess. Indeed, the spar can be paired with the fiber preform of the blade before the injection of the resin. Thus, this non-densified fiber preform (i.e. before injection of resin) is flexible and deformable to be able to ensure the filling of the recess of the spar with continuous fibers, then to carry out the injection of the resin and the densification of the fiber preform to obtain the rotor blade having the internal part of the spar connected to the blade by complementarity of shape.

[0016] Furthermore, the production of the recess at the level of at least one of the intrados and extrados faces of the spar is simpler and can be easily automated.

[0017] Thus, the overall performance of the rotor blade is greatly optimized.

[0018] The invention therefore has the advantage of being based on a simple design, offering very high reliability, and with little penalty in terms of cost and size.

[0019] The rotor blade according to the invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

[0020] - said at least one recess is filled with at least one material chosen from said resin, fibers of said fibrous preform and a foam;

[0021] - at least one block of foam is interposed between the fibrous preform and the part internal of the spar and comprises a portion housed in said at least one recess;

[0022] - the fibers of the fiber preform which fill said at least one recess are continuous fibers;

[0023] - said at least one recess is delimited by a bottom wall, on the one hand, and by side walls, on the other hand, these side walls extending from the bottom wall to the intrados or extrados face and defining between them a filling opening;

[0024] - the bottom wall has a surface area greater than a surface area of ​​the opening of filling;

[0025] - at least one side wall is connected to the bottom wall at an angle inclination between 20° and 89°, preferably the angle is between 30° and 60° ;

[0026] - the side walls are connected to the bottom wall and / or to the intrados or extrados face by fillets or chamfers;

[0027] - the filling opening has a general shape chosen from a trapezoid, rectangle, square, rhombus, triangle, circle or a mixture of at least two of said shapes;

[0028] - the internal part of the spar comprises several recesses provided on at least one of its intrados and extrados faces;

[0029] - the recesses located on the same intrados or extrados face have shapes and / or different dimensions;

[0030] - the recesses communicate with each other by at least one orifice;

[0031] - said at least one recess has in cross section a general shape trapezoidal or dovetail;

[0032] — the metallic material is aluminum, steel, titanium, nickel-based or any other type of metal or metal alloy.

[0033] The present invention also relates to an aircraft turbomachine, comprising at least one blade made of composite material according to the invention.

[0034] The turbomachine may be a turbojet, turboprop or aircraft turboshaft engine.

[0035] The present invention may relate to a method of manufacturing a rotor blade according to one of the features of the invention, the method comprising the steps of: (a) produce a rough draft of the fiber preform of the blade in composite material, (b) make the foot in metallic material formed from the spar with the external part and the internal part, (c) mounting the internal part of the spar in said blank, (d) inject the resin to obtain the rotor blade.

[0036] According to the invention, the method comprises in step (b), a sub-step (bj) of producing at least one recess on at least one of the intrados and extrados faces, so that said at least one recess is entirely filled during step (c) and / or (d).

[0037] Sub-step (bi) can be carried out by machining. This machining can be carried out by milling or sinking by electro-erosion (also designated by the English term “Electrical Discharge Machining” EDM) or by electro-chemical (also designated by the English term “ElectroChemical Machining” ECM). Brief description of the figures

[0038] The present invention will be better understood and other details, features and The advantages of the present invention will appear more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which:

[0039] [Fig.l] is a schematic perspective view of a blade root according to the prior art;

[0040] [Fig.2] is another schematic perspective view of the blade root of [Fig.l];

[0041] [Fig. 3] is a schematic perspective view of a non-aircraft turbomachine streamlined;

[0042] [Fig.4] is a half axial sectional view schematically representing a ducted, dual-flow aircraft turbomachine;

[0043] [Fig.5] is a perspective view schematically showing a rotor blade of [Fig.3] or [Fig.4];

[0044] [Fig.6] is a perspective view schematically representing a foot of the blade of [Fig.6] comprising a recess on one of the intrados and extrados faces according to a first embodiment of the invention;

[0045] [Fig.7] is a schematic view in cross-section and partial of the foot of [Fig.6];

[0046] [Fig.8] is an enlarged schematic cross-sectional view of a first example of the foot recess of [Fig.6] or [Fig.7];

[0047] [Fig.9] is a schematic cross-sectional view of a second example of the foot recess of [Fig.6];

[0048] [Fig. 10] is a schematic cross-sectional view of a third example of the foot recess of [Fig.6];

[0049] [Fig.1 1] is a cross-sectional view schematically representing a foot of the blade of [Fig.5] comprising a recess on the intrados and extrados faces according to a second embodiment of the invention;

[0050] [Fig. 12] is a partial cross-sectional view of a variant of the recesses of [Fig. 1 1];

[0051] [Fig. 13] is a cross-sectional view schematically showing a foot of the blade of [Fig. 5] comprising several recesses on the intrados and extrados faces according to a third embodiment of the invention;

[0052] [Fig. 14] is a partial cross-sectional view of a variant of the recesses of [Fig. 13];

[0053] [Fig. 15] is a perspective view schematically representing a foot of the blade of [Fig. 5] comprising several recesses on at least one of the intrados and extrados faces according to a fourth embodiment of the invention;

[0054] [Fig. 16] is a block diagram of a method of manufacturing the blade of the invention.

[0055] Elements having the same functions in different implementations have the same references in the figures. Detailed description of the invention

[0056] By convention, in the description below, the terms “longitudinal” and “axial” qualify the orientation of structural elements extending in the direction of a longitudinal axis (such as a turbomachine). The terms “radial” or “vertical” qualify an orientation of structural elements extending in a direction perpendicular to the longitudinal axis. The terms “inner” and “outer”, and “internal” and “external” are used with reference to a positioning relative to the longitudinal axis. Thus, a structural element extending along the longitudinal axis has an inner face facing the longitudinal axis and an outer surface, opposite its inner surface. Similarly, the terms “upstream” and “downstream” are defined with respect to the direction of circulation of the gases in the aircraft propulsion unit.

[0057] The invention can be applied in a non-limiting manner to a turbomachine 1, in particular an aircraft turbomachine. The turbomachine 1 can be a turbojet, turboshaft or turboprop.

[0058] The turbomachine 1 extends around a longitudinal axis X.

[0059] The turbomachine 1 may have an unducted architecture, such as an “Open Rotor” type turbomachine, which is for example shown in [Fig.3].

[0060] The turbomachine 1 may have a shrouded architecture, such as a dual-flow turbomachine, which is for example shown in [Fig.4].

[0061] The turbomachine 1 of [Fig.3] or 4 may comprise a propeller 2a upstream of a rectifier 2b downstream.

[0062] Conventionally, the turbomachine 1 comprises from upstream to downstream in the direction of flow of the gases F, the propeller (or fan) 2a, at least one compressor (such as a low-pressure compressor 1a and a high-pressure compressor 1b), a combustion chamber 1c, at least one turbine (such as a high-pressure turbine 1d and a low-pressure turbine 1c), and possibly a nozzle. The rotor of the low-pressure compressor 1a is driven by the rotor of the low-pressure turbine 1d. The rotor of the high-pressure compressor 1b is driven by the rotor of the high-pressure turbine 1c.

[0063] The rectifier 2b of [Fig. 3] or 4 may comprise at least one annular row of so-called stator vanes which are in particular fixed. These stator vanes are also known by the English abbreviation OGV for “Outlet Guide Vane”.

[0064] The stator blades make it possible to straighten the flow at the outlet of a rotor located upstream in order to provide maximum thrust at the outlet of the turbomachine 1. In the particular example of [Fig.4], the straightener 2b is located downstream of the propeller 2a and allows a secondary flow F2 to be rectified.

[0065] The propeller 2a (or fan) of [Fig. 3] or 4 may comprise at least one annular row of so-called rotor blades which are in particular movable in rotation around the axis X. In the particular example of [Fig. 4], the propeller 2a allows the suction of an air flow dividing into a primary flow F1 and a secondary flow F2. The primary flow F1 passes through a primary vein of the turbomachine 1 while the secondary flow F2 is directed towards a secondary vein surrounding the primary vein.

[0066] The primary flow F1 is compressed within the low-pressure compressor 1a and then the high-pressure compressor 1b. The compressed air is then mixed with a fuel and burned within the combustion chamber 1c. The gases formed by the combustion pass through the high-pressure turbine 1d and the low-pressure turbine 1c. The gases finally escape through the nozzle, the cross-section of which allows the acceleration of these gases to generate propulsion. The secondary flow F2 passes through the rectifier 2b, which accelerates the circulation speed of the secondary flow F2 to generate propulsion.

[0067] In the following description, the invention will be described in the context of its application to the rotor blade 3, in particular with reference to FIGS. 5 to 15, which can be installed in the turbomachine 1 shrouded ([Fig.4]) or unshrouded ([Fig.3]).

[0068] The rotor blade 3 (simplified below by blade 3) can extend as follows: - an elongation axis A (substantially vertical in the figures) which can be substantially perpendicular or inclined to the axis X of the turbomachine 1, - a longitudinal axis B (substantially horizontal in the figures) extending perpendicular to axis A, and - a transverse axis C extending perpendicular to axes A and B.

[0069] With reference to [Fig.5], the blade 3 generally comprises a blade 4 connected to a root 5.

[0070] The blade 4 is made of composite material and formed by a fiber preform embedded in a resin.

[0071] The composite material may be, for example, an organic matrix composite (OMC). The resin may be, for example, a thermoplastic or thermosetting polymer resin. The thermosetting material is, for example, an epoxy polymer. The fiber preform may comprise fibers which are, for example, carbon, glass, aramid, or ceramic fibers such as silicon carbide.

[0072] The blade 4 comprises a lower surface 42 and an upper surface 44 connected to each other by a leading edge 46 upstream and a trailing edge 48 downstream of the blade 4.

[0073] The blade 4 may have an aerodynamic profile to form the aerodynamic part of the blade 3. For this, the blade 4 may have a curved profile of variable thickness between the leading edge 46 and its trailing edge 48.

[0074] In the example of Figure 5, the blade 3 may also comprise a protective sheath 6. The protective sheath 6 makes it possible to protect the blade against external impacts (gravel from a takeoff / landing runway, hailstones, birds, etc.) and against erosion of the blade.

[0075] In the present application, the term “protective sheath” means a member of variable shape (for example which has a U or V shape in cross section relative to the axis A) which at least partially covers the leading edge 46 of the blade 4.

[0076] The protective sheath 6 may be a metal reinforcement, a metal shield, a metal foil or any other form making it possible to cover at least part of the leading edge of the blade.

[0077] The metallic material of the protective sheath 6 is for example titanium or an alloy such as steel (for example stainless steel) or a nickel and cobalt alloy (NiCo).

[0078] The blade 4 can extend along the axis A between a first end 41 and a second end 43 opposite the first end 4L. In the example of [Fig. 5], the first end 41 is free and configured to form a top (or a head) of the blade 4 (and consequently of the blade 3). The second end 43 is connected to the blade root 5.

[0079] The foot 5 is in particular intended to be fixed to a rotor disk (not shown) of the turbomachine 1, for example mobile in rotation around the axis X.

[0080] The foot 5 is made of a metallic material. For example, the metallic material is aluminum, steel, titanium, nickel-based or any other type of metal or metal alloy.

[0081] The foot 5 may have a first maximum height H5 measured substantially along the axis A.

[0082] One of the structural elements of the blade 3 is the metal root 5, also forming a spar, since it provides the connection between the rotor disk and the blade 3. The spar of the root 5 comprises an internal part 52 and an external part 54. In [Fig.5], this external part 54 extends outside the blade 4 to form, for example, a cylindrical-shaped attachment to the rotor disk.

[0083] The internal 52 and external 54 parts of the spar are preferably monobloc (i.e. made in one piece).

[0084] The internal portion 52 of the spar may have a first total or maximum thickness E52 which is measured along the axis C. This internal portion 52 may have a first maximum length L52 measured substantially along the axis B.

[0085] The internal part 52 is engaged in the fiber preform of the blade 4 (in particular at the level of the second end 43). The internal part 52 thus comprises an intrados face 522 located on the side of the intrados 42 of the blade 4 and an extrados face 524 located on the side of the extrados 44. In this configuration, at least a part of the blade 4 (and in particular the second end 43) can extend around and cover the internal part 52 of the spar.

[0086] Furthermore, the blade 3 may comprise at least one element made of cellular material 7. This element made of cellular material 7 may be located in the blade 4 (in particular at the level of the second end 43) in order in particular to lighten the overall mass of the blade. More particularly with reference to [Fig. 5], the element made of cellular material 7 extends between the fiber preform of the blade 4 and the internal part 52 of the spar. The element made of cellular material 7 may be a foam.

[0087] One of the particularities of the invention is that the internal part 52 of the spar comprises at least one recess 50, 50a, 50b formed on at least one of the intrados 522 and extrados 524 faces, this recess being entirely filled. This is in order to facilitate and reinforce the integration between the root 5 made of metallic material and the blade 4 made of composite material, while lightening the general mass of the blade.

[0088] The term "filled" means the recess of the invention which is entirely (either totally or 100%) occupied, in particular by a material (such as resin, fibers and / or a foam), without empty or unoccupied space or area in this recess.

[0089] The recess is shown in dotted lines in the figures.

[0090] The internal part 52 of the spar may comprise several recesses 50, 50a, 50b arranged on at least one of its intrados 522 and extrados 524 faces. For example, the intrados face 522 may comprise one or more first recesses 50, 50a and / or the extrados face 524 may comprise one or more second recesses 50, 50b.

[0091] The first recess(es) 50a may be symmetrical or asymmetrical to the second recess(es) 50b with respect to a plane of symmetry PA passing through the axis A.

[0092] The number of recesses 50, 50a, 50b may vary depending on the shape and dimensions of the root 5 and / or generally of the blade 3. For example, the intrados face 522 and / or the extrados face 524 may comprise between one and ten recesses 50, 50a, 50b.

[0093] The recesses 50, 50a, 50b located on the same intrados face 522 or extrados face 524, may have shapes and / or dimensions (such as similar or different from each other.

[0094] When the internal part 52 comprises several recesses arranged on one of the intrados and extrados faces 522, 524 and / or both intrados and extrados faces 522, 524, these recesses 50a, 50b can communicate with each other via at least one orifice 512, 512a, 512b. The orifice 512, 512a, 512b can extend according to at least one of the following configurations: - transversely (relative to the axis C) from the first recess 50a to the second recess 50b, and / or - radially (relative to the axis A) from one of the first recesses 50a towards another of the first recesses 50a, and / or - radially (relative to the axis A) from one of the second recesses 50b towards another of the second recesses 50b.

[0095] The orifice 512, 512a, 512b may extend substantially perpendicular or inclined to the bottom wall 510 (or relative to the axis A).

[0096] This orifice 512, 512a, 512b may have a third thickness E5i2a, E5i2b measured relative to the axis C. This third thickness E5i2 may be identical to or less than the second thickness E50 of the recess 50, 50a, 50b.

[0097] Each recess 50, 50a, 50b can be filled with at least one material 521 chosen from the resin of the blade 4, fibers of the fiber preform of the blade 4 and a foam 526.

[0098] The recess 50, 50a, 50b can be filled with the fibers of the fiber preform of the blade 4. These fibers can be continuous to ensure the rigidity of the blade and the partial or complete filling of the recess of the spar.

[0099] By "continuous fibers" is conventionally meant fibrous elements having a very great length in relation to their diameter. Thus, in the case for example of a reinforcement structure constituting a preform of a part made of composite material and made from continuous fibers, at least a very large majority of these extend continuously in this preform while being interrupted only at the geometric limits of the preform.

[0100] Advantageously, at least one block of foam 526 can be inserted between the fiber preform of the blade 4 and the internal part 52 of the spar and this block of foam 526 comprises a part housed in the recess 50, 50a, 50b.

[0101] With reference to Figures 6 to 14, the recess 50, 50a, 50b may be delimited by a bottom wall 510, on the one hand, and side walls 502, 54, 506, 508, on the other hand.

[0102] The side walls 502-508 may form first 502 and second 504 side walls extending radially along the axis A, and third 506 and fourth 508 side walls extending longitudinally along the axis B.

[0103] In the example, each of the side walls 502-508 may extend from the bottom wall 510 to the filling opening 500.

[0104] The side walls 502-508 may extend from the bottom wall 510 to the intrados face 522 or extrados face 524 and define between them a filling opening 500.

[0105] The bottom wall 510 may be substantially flat and parallel or inclined relative to the axis A.

[0106] At least one of the side walls 502-508 may be planar and inclined relative to the axis A. Preferably, all of the side walls 502-508 may be planar and inclined relative to the A axis.

[0107] At least one of the side walls 502-508 may be connected to the bottom wall 510 and / or to the intrados face 522 or extrados face 2524 (in particular at the level of the opening 500) by a fillet or a chamfer. In other words, one of the side walls 502-508 may be connected to the bottom wall 510 by a connecting end 506a, 506b, 508a, 508b which may have a rounded profile in cross section (relative to the axis C). The rounded profile of this connecting end may be convex or concave. This makes it possible to avoid forming sharp angles (or cutting edges which can generate cracks on the blade in operation) connecting the bottom wall 510 and one of the side walls 502-508 and thus to avoid damaging the blade 4, in particular the material 521 filling the recess.

[0108] The bottom wall 510 has a first surface S5i0 greater than a second surface S5Oo of the filling opening 500.

[0109] The filling opening 500 may have a general shape chosen from a trapezoid, rectangle, square, diamond, triangle, circle or a mixture of at least two of these shapes.

[0110] At least one side wall 502-508 is connected to the bottom wall 510 at an angle a of inclination of between 20° and 89°. Preferably, the angle a can be between 30° and 60°. The angle a makes it possible to form an acute angle making it possible to reinforce the connection between the spar made of metallic material and the blade 4 made of composite material.

[0111] Each recess 50, 50a, 50b may have a second maximum height H50 measured along the axis A. This second height H50 may be less than the first height H5. For example, the second height H50 may represent between 20 and 75% of the first height E50 of the foot 5.

[0112] Each recess 50, 50a, 50b may have a second maximum length L50 measured along the axis B. This second length L50 may be less than the first length L5. For example, the second length L50 may represent between 20 and 80% of the first length L5 of the internal part 52 of the spar.

[0113] Each recess 50, 50a, 50b may have a second thickness E50 (or in other words a depth) measured along the axis C. The second thickness E50 may be constant or variable along the axis C. This second thickness E50 may be less than the first total thickness E52 of the internal part 52 of the spar. The second thickness E50 may vary depending on the arrangement of recess(es) on one or both of the intrados 522 and extrados 524 faces. Preferably, each recess may be provided while retaining a third thickness, called residual, of the spar. Thus, the second thickness E50 may correspond to the difference between the first total thickness E52 of the internal part 52 of the spar and the third thickness side. For example, this third thickness can be between 2 and 5 mm. For example, the second thickness E50 can represent between 20 and 80% of the total first thickness E52. For example, the second thickness E50 can be between 5 and 50 mm.

[0114] Advantageously, the recess(es) may cover a maximum surface area of ​​90% of the internal part 52 of the spar. Preferably, the recesses are not provided on peripheral edges of the internal part 52 of the spar which are on the side of the leading and trailing edges of the blade. For example, each recess may have a surface area of ​​between 50x50 mm and 200x500 mm, in particular depending on the dimension of the spar.

[0115] The shape (such as that of the opening 500) and / or the dimension (such as the second height H50, second length L50, second thickness E50, the surface area, the number, etc.) of each recess 50, 50a, 50b may vary depending on the shape and dimensions of the root and / or generally of the blade.

[0116] Each recess 50, 50a, 50b may have a generally trapezoidal or dovetail shape in cross-section (relative to the axis C). This makes it possible to form the first surface S5i0 greater than the second surface S5Oo and thus facilitate the retention of the blade 4 made of composite material.

[0117] The present application will now describe the different possible configurations of the rotor blade 3 with the recess(es) 50, 50a, 50b with reference to FIGS. 6 to 15.

[0118] Figures 6 to 10 illustrate in a non-limiting manner a first embodiment of the blade 3 as described above, in which a single recess 50 can be provided only on the intrados face 522 (or the extrados face 524) of the spar.

[0119] In the example of Figures 6 and 7, the recess 50 on the intrados face 522 is shown without the material 521. This recess 50 is intended to be filled entirely by the material 521 chosen from the resin of the fiber preform, the fibers of the fiber preform, and a foam 526. The recess 50 comprises an opening 500 with a general trapezoidal shape. The recess 50 has in cross section the general trapezoidal or dovetail shape. The first surface S5i0 of the bottom wall 510 is greater than the second surface S5Oo of the opening 500. The side walls 502-508 (in particular the third and fourth side walls 506, 508 visible in cross section) are flat and inclined relative to the axis A. The bottom wall 510 is flat and substantially parallel to the axis A.The side walls 502-508 (in particular the third and fourth side walls 506, 508 visible in cross section) are connected to the bottom wall 510 by the angle a of inclination. This angle a is approximately 60° in the examples of [Fig.6].

[0120] [Fig.8] illustrates a first variant of the recess 50 compared to figures 6 and 7, wherein the recess 50 filled by the material 521 comprises side walls 502-508 (in particular the third 506 and fourth 508 side walls) connected to the bottom wall 510 by chamfers. In particular, the third 506 and fourth 508 side walls comprise first connecting ends 506b, 508b to the bottom wall 510 which have chamfers (or concave profiles). The material 521 filling this recess 50 can be chosen from the resin of the fiber preform, the fibers of the fiber preform, and a foam 526.

[0121] [Fig. 9] illustrates a second variant of the recess 50 with respect to FIGS. 6 and 7, in which the recess 50 filled by the material 521 comprises side walls 502-508 (in particular the third 506 and fourth 508 side walls) having both: - first connecting ends 506b, 508b to the bottom wall 510 which have chamfers, and - second connecting ends 506a, 508a to the intrados face 522 (or extrados face 524 in another alternative) which have fillets.

[0122] The material 521 filling this recess 50 can be chosen from the resin of the fiber preform, the fibers of the fiber preform, and a foam 526.

[0123] [Fig. 10] illustrates a third variant of the recess 50 compared to FIGS. 6 and 7, in which the recess 50 filled by the material 521 may comprise fibers and / or the resin of the fiber preform of the blade 4 and a block of foam 526. This block of foam 526 may be interposed between the fiber preform and the internal part 52 of the spar and at least a part of the block of foam 526 is housed in the recess 50.

[0124] With reference to [Fig. 10], the foam block 526 may be entirely housed in at least a portion of the recess 50 and extend over the bottom wall 510, and the remainder of the recess 50 may be filled with the resin and / or the fibers of the fiber preform of the blade 4.

[0125] Figures 11 and 12 illustrate in a non-limiting manner a second embodiment of the rotor blade 3 which differs from the blade 3 of the first embodiment by the arrangement of the recess 50, 50a, 50b without the material 521. As mentioned previously, this recess 50, 50a, 50b is intended to be filled entirely by the material 521. In particular, the internal part 52 of the spar comprises a first recess 50a formed on the intrados face 522 and a second recess 50b formed on the extrados face 524. In particular, the first recess 50a can be symmetrical to the second recess 50b with respect to the plane of symmetry PA passing through the axis A. Thus, the first 50a and second 50b recesses can have the same dimensions (such that the same second heights H50, lengths L50 and / or thicknesses E5oa>5ob)-

[0126] The first 50a and second 50b recesses may be similar and have the same characteristics as the recess 50 described with reference to figures 6 and 7.

[0127] The first 50a and second 50b recesses are intended to be filled entirely with the material 521 chosen from the resin of the fiber preform, the fibers of the fiber preform, and a foam 526.

[0128] In [Fig. 11], the first 50a and second 50b recesses are separated from each other by the symmetrical plane PA, and in particular by the so-called central body of the internal part 52 of the spar.

[0129] [Fig. 12] illustrates a variant of the first 50a and second 50b recesses with respect to [Fig. 11], in which the first 50a and second 50b recesses can communicate with each other via the first orifice 512, 512a. This first orifice 512, 512a extends substantially perpendicular to the bottom wall 510 (or with respect to the axis A). The third thickness E5i2a of this first orifice 512a is less than those of the second thicknesses E50aj50b of the recesses 50a, 50b. [Fig. 12] illustrates in a non-limiting manner a single first orifice 512, 512a. In another alternative, the first 50a and second 50b recesses can communicate with each other via several first orifices 512, 512a.

[0130] Figures 13 and 14 illustrate in a non-limiting manner a third embodiment of the rotor blade 3 which differs from the blade 3 of the first and second embodiments also by the arrangement of the recess 50, 50a, 50b without the material 521. As mentioned previously, this recess 50, 50a, 50b is intended to be filled entirely by the material 521. In particular, the internal part 52 of the spar comprises several first recesses 50a arranged on the intrados face 522 and several second recesses 50b arranged on the extrados face 524. In the example and in a non-limiting manner, the first 50a and second 50b recesses are three in number. The first recesses 50a and / or the second recesses 50b may be distributed regularly (in particular along the axis A) or randomly on the intrados face 522 or the corresponding extrados face 524.The first recesses 50a may be symmetrical to the second recess 50b with respect to the plane of symmetry PA passing through the axis A. Thus, the first 50a and second 50b recesses may have the same dimensions (such as the same second heights H50, lengths L50 and / or thicknesses E50aj50b).

[0131] [Fig. 14] illustrates a variant of the first 50a and second 50b recesses with respect to [Fig. 13], in which these first and second recesses 50a, 50b can communicate with each other via several orifices 512, 512a, 512b. In particular, the first 50a and second 50b recesses can have both:

[0132] - first orifices 512a extending between one of the first recesses 50a and one of the second recesses 50b, and

[0133] - at least one second orifice 512b extending between the first recesses 50a (in particular two adjacent first recesses 50a) and / or between the second recesses 50b (in particular two adjacent second recesses 50b).

[0134] Thus, each first orifice 512a can extend substantially perpendicular to the bottom wall 510 (or relative to the axis A) and the second orifice 512b can extend substantially parallel to the bottom wall 510 (or relative to the axis A). The third thickness E5i2b of this second orifice 512b is less than those of the second thicknesses E50a> 50b of the recesses 50a, 50b. [Fig. 14] illustrates in a non-limiting manner two first orifices 512a connecting each of the first 50a recesses to the second 50b recess, the first recesses 50a to each other and the second recesses 50b to each other by a single second orifice 512b. Alternatively, several second orifices 512b can connect, on the one hand, the first recesses 50a to each other, and on the other hand, the second recesses 50b to each other separately.

[0135] [Fig. 15] illustrates in a non-limiting manner a fourth embodiment of the rotor blade 3 which differs from the blade 3 of the first, second and third embodiments also by the arrangement of the recess 50, 50a, 50b without the material 521. As mentioned previously, this recess 50, 50a, 50b is intended to be filled entirely by the material 521. In particular, the internal part 52 of the spar comprises several first recesses 50, 50a arranged on the intrados face 522 (and / or several second recesses 50, 50b arranged on the extrados face 524). In the example and in a non-limiting manner, the first 50a recesses are six in number and of different shapes. Indeed, the openings 500 of the first recesses 50a are in a non-limiting manner in the form of a trapezoid, rectangle, diamond and triangle. These first recesses 50a can be distributed randomly on the intrados face 522.

[0136] The present application will now describe a method of manufacturing the rotor blade 3 as described below with reference to FIGS. 5 to 15, the successive steps of which are for example summarized in [Fig. 16].

[0137] The method may comprise the steps of: (a) producing a rough draft of the fiber preform of the blade 4 in composite material, (b) producing the foot 5 in metallic material formed from the spar with the internal part 52 and the external part 54, (c) mount the internal part 52 of the spar in the blank, (d) inject the resin to obtain the rotor blade 3.

[0138] This method comprises in step (b), a sub-step (bj) of producing at least one recess 50, 50a, 50b on at least one of the intrados 522 and extrados 524 faces, so that this recess 50, 50a, 50b is entirely filled during step (c) and / or (d). Thus, the recess 50, 50a, 50b can be preformed on the internal part 52 of the spar before mounting the root 5 in the fiber preform of the blade 4.

[0139] In step (a), the roughing of the fiber preform of the blade 4 can be produced by weaving of fibers, particularly in 3D or by draping several layers of fibers.

[0140] In step (b), the foot 4, and in particular the internal 52 and external 54 parts, can be produced by forging the metallic material.

[0141] In sub-step (bi), the recess(es) 50, 50a, 50b may be produced by machining. This machining may be carried out by milling or sinking by electro-erosion (EDM) or by electro-chemical (ECM).

[0142] In step (d), the injection of the resin can be carried out by the RTM technique.

Claims

Claims

1. Rotor blade (3) for a turbomachine (1), in particular an aircraft, the blade (3) extending along an elongation axis (A) and comprising a blade (4) connected to a root (5), the blade being made of composite material and being formed by a fiber preform embedded in a resin, the blade (4) comprising a lower surface (42) and an upper surface (44) connected to each other by a leading edge (46) and a trailing edge (48) of the blade, the root (5) being made of metallic material and formed by an external part (54) of a spar which also comprises an internal part (52), this internal part (52) being engaged in the preform of the blade (4) and comprising an intrados face (522) located on the side of the intrados (42) of the blade and an extrados face (524) located on the side of the extrados (44) of the blade, characterized in that that the internal part (52) of the spar comprises at least one recess (50, 50a, 50b) provided on at least one of its intrados and extrados faces (522, 524),said at least one recess (50, 50a, 50b) being entirely filled.,

2. Rotor blade according to claim 1, characterized in that said at least one recess (50, 50a, 50b) is filled with at least one material (521) chosen from said resin, fibers of said fiber preform and a foam (526).

3. Rotor blade according to claim 2, characterized in that at least one block of foam (526) is interposed between the fibrous preform and the internal part (52) of the spar and comprises a part housed in said at least one recess (50, 50a, 50b).

4. Rotor blade according to claim 2 or 3, characterized in that the fibers of the fiber preform which fill said at least one recess (50, 50a, 50b) are continuous fibers.

5. Rotor blade according to one of claims 1 to 4, characterized in that said at least one recess (50, 50a, 50b) is delimited by a bottom wall (510), on the one hand, and by side walls (502, 504, 506, 508), on the other hand, these side walls (502, 54, 506, 508) extending from the bottom wall (510) to the intrados or extrados face (522, 524) and defining between them a filling opening (500).

6. Rotor blade according to the preceding claim, characterized in that the bottom wall (510) has a surface (S5i0) greater than a surface (S5Oo) of the filling opening (500).

7. Rotor blade according to claim 5 or 6, characterized in that at least one side wall (502, 504, 506, 508) is connected to the bottom wall (510) at an angle (a) of inclination between 20° and 89°, preferably the angle (a) is between 30° and 60°.

8. Rotor blade according to any one of claims 5 to 7, characterized in that the side walls (502, 504, 506, 508) are connected to the bottom wall (510) and / or to the intrados or extrados face (522, 524) by fillets or chamfers.

9. Rotor blade according to any one of claims 5 to 8, characterized in that the filling opening (500) has a general shape chosen from a trapezoid, rectangle, square, diamond, triangle, circle or a mixture of at least two of said shapes.

10. Rotor blade according to any one of the preceding claims, characterized in that the internal part of the spar comprises several recesses (50, 50a, 50b) provided on at least one of its intrados and extrados faces (522, 524).

11. Rotor blade according to claim 10, characterized in that the recesses (50, 50a, 50b) located on the same intrados (522) or extrados (524) face have different shapes and / or dimensions.

12. Rotor blade according to claim 10 or 11, characterized in that the recesses (50a, 50b) communicate with each other via at least one orifice (512, 512a, 512b).

13. Rotor blade according to any one of the preceding claims, characterized in that said at least one recess (50, 50a, 50b) has a generally trapezoidal or dovetail shape in cross section.

14. Aircraft turbomachine (1) comprising at least one rotor blade (3) according to any one of the preceding claims.

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