TURBOMACHINES FAN BLADE, FAN AND TURBOMACHINES WITH SUCH A BLADE

Description

[0001] The invention relates to a turbomachine rotary fan blade, a turbomachine rotary fan provided therewith and a turbomachine provided therewith.

[0002] The field of the invention relates to aircraft turbomachines, in particular turbojets or turboprops.

[0003] Document US 2008 / 159868 relates to a turbomachine blade having a fusible part at the blade tip.

[0004] Document US 2019 / 242260 relates to a blade having a frangible zone on its upper part.

[0005] Document EP 1 908 919 relates to a turbomachine blade having a hollow cavity opening at the tip of the blade.

[0006] It is known that the rotating fan blades of a turbomachine rotate in a fixed casing surrounding them with a clearance between the blades and the casing, which is internally covered with an abradable material that can be planed by the rotating blade tips. Document EP-A-1 312 762 describes such blades, the tips of which are capable of being disintegrated by the internal wall of the retention casing in the event of an impact following the occurrence of an unbalance having caused the decoupling of the bearing, in order to obtain a greater clearance necessary for the operation of the decoupler. According to this document, each blade has near its tip a weakened zone produced by means of a groove arranged, parallel to its tip, on the extrados face. This groove is filled with a resin which ensures the aerodynamic continuity of the extrados in the vicinity of the tip.The groove is formed in the base material of the blade to a depth such that the remaining wall of base material of the weakened zone on the leading edge, intrados and trailing edge sides has sufficient strength to allow the planing of the layer of abradable material and is sufficiently brittle to break upon the occurrence of an impact between the tip of the blade and the inner wall of the retention casing.

[0007] The rotational movement R of the motor rotating the blade 2 with the association of various external elements such as for example the ingestion of birds, or vibratory phenomena, can induce sudden and significant contacts between the blade head 27 and the abradable 301 located on the casing 300 of the fan, as shown in figure 1 .

[0008] This contact between the blade and the casing can cause significant damage. Indeed, a sudden, one-off contact can lead to deformation of the blade, which will increase the contact in terms of blade surface area or contact depth in the abradable material. If the phenomenon is not controlled, this can result in damage to the blade, leading to significant material losses.

[0009] To avoid this scenario, the radial clearance J at the head of the fan 280 and the volume of the blade 2 are sized so as to prevent the latter from engaging in the abradable material to the point of damaging the engine.

[0010] Studies have shown that when the blade operates at high speed, it deforms under the centrifugal effect and aerodynamic forces. The radial clearance J at the blade tip decreases and it turns out that in certain cases, this clearance J does not provide a sufficient margin to avoid contact between the blade tip 27 and the abradable material. This friction induces a tangential load on the blade tip 27, shown diagrammatically by the arrows F of the figure 2 , directed from the intrados 24 towards the extrados 25 of the blade 2 and this in the direction opposite to the rotation of the blade 2 around the axis AX of rotation of the engine.

[0011] This stress causes additional deformation of the blade. Several cases can then arise.

[0012] According to a first case, if this deformation induces an increase in clearance so as to reduce the forces and disengage the blade from the abradable, the blade is defined as non-self-engaging. It is then considered that in this first case the behavior of the blade is healthy when it comes into contact with the abradable.

[0013] On the contrary, according to a second case, if a positive clearance consumption is induced by the deformation, the blade is defined as self-engaging. In this second case, the blade will continue to sink into the abradable and the forces on the blade will increase. The blade and the surrounding parts of it can then suffer serious damage.

[0014] The simplest solution to avoid this self-engagement phenomenon or at least reduce its criticality is to increase the clearance at the blade tip in order to have an additional margin before the blade contacts the abradable material. This strategy avoids any damage to the engine but can have a significant impact on the aerodynamic performance of the blade. Increasing the clearance at the tip increases the leakage flow and the associated losses in this area.

[0015] In addition, it is sought to avoid configurations of the leading edge of the blade head which, in the event of self-engagement, are difficult to detach due to their geometric profile and increase the criticality of self-engagement.

[0016] A first objective of the invention is to obtain a rotating turbomachine fan blade, making it possible to limit the criticality of self-engagement on the leading edge of the blade head without deteriorating the aerodynamic performance.

[0017] A second objective of the invention is to obtain a rotating turbomachine fan blade, making it possible to avoid configurations of the leading edge of the blade head which, in the event of self-engagement, are difficult to detach due to their geometric profile and increase the criticality of self-engagement.

[0018] To this end, a first object of the invention is a rotating turbomachine fan blade, the blade comprising: a body made of a composite material, having an upstream edge and a downstream edge, between which the body extends in a first longitudinal direction, an extrados and a intrados, between which the body extends in a second thickness direction, which is transverse to the first direction, a blade root and a blade tip edge, between which the body extends in a third height direction, transverse to the first and second directions, the blade root having the function of fixing to a longitudinal rotating fan hub, a metal reinforcing part comprising a metal upstream nose, which forms a leading edge of the blade and which is fixed to the upstream edge, a first metal fin, which is connected downstream of a first extrados flank of the metal upstream nose and which is fixed to an upstream part of the extrados, and a second metal fin,which is connected downstream of a second intrados flank of the upstream metal nose and which is fixed to an upstream part of the intrados, the upstream metal nose having a metal blade tip part, located upstream of the blade tip edge, the upstream metal nose comprising at least on the metal blade tip part at least one recess, which is of longitudinally tapered thickness and which opens in the third height direction onto the metal blade tip part, the at least one recess delimiting on the metal blade tip part over a non-zero height determined in the third height direction at least one prescribed metal wear projection,which is of longitudinally tapered thickness over a major part of a length of the upstream metal nose in the first longitudinal direction and which is configured to detach at least partially in the presence of tangential friction going in the second thickness direction against the metal part of the blade head, the at least one recess and the at least one prescribed wear metal projection extending in the first longitudinal direction upstream the first metal fin and / or the second metal fin and / or the upstream edge of the body made of composite material.

[0019] By virtue of the invention, the prescribed metal wear protrusion provided at the level of the metal blade head may be sufficient to prevent self-engagement of the entire blade from its leading edge. The wear of the prescribed metal wear protrusion of the blade head during its possible rotation against the abradable material of the fan casing may be progressive to maintain a sufficient height of the blade head reducing the leakage flow between the blade and this casing, while preventing self-engagement in the second case mentioned above. The prescribed breakage protrusion or fusible zone on a self-engaging blade allows the blade to be disengaged upon contact, thus limiting damage to the blade head. Thus, rather than changing numerous parts during a critical event leading to a phenomenon of self-engagement of the blade, only the blade may be repaired or replaced.The determination of blade tip clearances no longer takes into account the self-engaging nature of a blade. It is then possible to reduce the clearances, which improves the aerodynamic performance of the blade. Thus, the sizing of a blade according to the engine target (diameter, rotational speed, etc.) will determine the optimal solution for achieving the prescribed rupture zone among the proposed embodiments.

[0020] According to one embodiment of the invention, the longitudinally tapered thickness of the prescribed metal wear projection is constant at least over a portion of the determined non-zero height.

[0021] According to one embodiment of the invention, the longitudinally tapered thickness of the prescribed metal wear protrusion is constant over a major portion of a length of the metal upstream nose.

[0022] According to one embodiment of the invention, the metal blade head portion has a thickness increasing in a direction from upstream to downstream, the at least one recess is delimited by edges of the metal upstream nose, the thickness occupied by the at least one recess relative to the edges increasing in the direction from upstream to downstream over a major part of a length of the metal upstream nose.

[0023] According to one embodiment of the invention, the metal part of the blade head has a thickness increasing in a direction going from upstream to downstream, the at least one recess is delimited by edges of the metal upstream nose, said determined non-zero height, occupied by the at least one recess relative to the edges, decreasing in a direction going from upstream to downstream over a major part of a length of the metal upstream nose.

[0024] According to one embodiment of the invention, the at least one recess is formed by at least one shoulder, which is connected to the first extrados flank of the metal upstream nose. The shoulder may incorporate a curve.

[0025] According to one embodiment of the invention, the at least one recess is formed by a shoulder, which is connected to the second intrados flank of the upstream metal nose. The shoulder may incorporate a curve.

[0026] According to one embodiment of the invention, the metal upstream nose comprises as a recess at least a first recess, which is formed by a first shoulder connected to the first extrados flank of the metal upstream nose, and at least a second recess, which is formed by a second shoulder connected to the second intrados flank of the metal upstream nose. The shoulder may include a curve.

[0027] According to one embodiment of the invention, the shoulder is curved.

[0028] According to one embodiment of the invention, the prescribed wear metal projection surrounds the at least one recess.

[0029] According to one embodiment of the invention, the blade tip edge has a further prescribed wear projection, which is of longitudinally tapered thickness and which extends the prescribed metal wear projection. Thus, if the projection of the reinforcing piece is considered a first projection, the further prescribed wear projection on the blade tip edge of the blade body is an additional projection supplementing the first projection of the metal reinforcing piece in its extension in the first longitudinal direction.

[0030] A second subject of the invention is a turbomachine rotary fan, comprising a longitudinal rotating fan hub and a plurality of blades as described above, which are fixed at their blade root to the longitudinal rotating fan hub.

[0031] A third subject of the invention is a turbomachine comprising a rotary fan as described above, and, downstream of the fan, a low pressure compressor, a high pressure compressor, a combustion chamber, a high pressure turbine and a low pressure turbine.

[0032] The invention will be better understood upon reading the description which follows, given solely by way of non-limiting example with reference to the figures below of the attached drawings. [ Fig. 1 ] represents a schematic front view of a blade according to the state of the art. [ Fig. 2] represents a schematic view along a radial direction of the head of a blade according to the state of the art. [ Fig. 3 ] represents a schematic axial sectional view of a turbomachine, comprising the blade according to the invention. [ Fig. 4 ] represents a schematic perspective view of a blade according to an embodiment of the invention. [ Fig. 5 ] represents an enlarged schematic perspective view of the head of the blade according to a first embodiment of the invention. Fig. 6 ] represents an enlarged schematic cross-sectional view of the blade head according to the first embodiment of the invention. Fig. 7 ] represents an enlarged schematic perspective view of the head of the blade according to a second embodiment of the invention. Fig. 8 ] represents an enlarged schematic cross-sectional view of the blade head of the figure 7 according to the second embodiment of the invention. [ Fig. 9] represents an enlarged schematic view from above of the blade head of the figure 7 according to one embodiment of the invention. [ Fig. 10 ] represents an enlarged schematic perspective view of the head of the dawn of the figure 7 according to a variant of the second embodiment of the invention in which the height of a recess decreases from upstream to downstream. Fig. 11 ] represents an enlarged schematic perspective view of the head of the blade according to a third embodiment of the invention. Fig. 12 ] represents an enlarged schematic perspective view of the head of the blade according to a fourth embodiment of the invention. [ Fig. 13 ] represents an enlarged schematic cross-sectional view of a portion of the blade head according to a fifth embodiment of the invention. Fig. 14] represents an enlarged schematic cross-sectional view of a portion of the blade head according to a sixth embodiment of the invention. Fig. 15 ] represents an enlarged schematic cross-sectional view of a portion of the blade head according to a seventh embodiment of the invention. Fig. 16 ] represents an enlarged schematic perspective view of the head part of the blade of the figure 15 according to the seventh embodiment of the invention. [ Fig. 17 ] represents an enlarged schematic perspective view of a part of the head of the blade according to an eighth embodiment of the invention.

[0033] This is described in more detail below with reference to the figure 3 an example of a turbomachine 1 on which the rotary fan blade(s) 2 according to the invention can be used.

[0034] As is known, the turbomachine 1 shown in the figure 3is intended to be installed on an aircraft not shown to propel it into the air.

[0035] The gas turbine engine assembly or turbomachine 1 extends around an axis AX or axial direction AX (or first longitudinal direction AX mentioned below) oriented from upstream to downstream. Subsequently, the terms "upstream", respectively "downstream" or "front", respectively "rear", or "left" respectively "right" or "axially" are taken along the general direction of the gases which flow in the turbomachine along the axis AX. The direction going from the inside to the outside is the radial direction DR (or third height direction DR mentioned below) starting from the axis AX.

[0036] The turbomachine 1 is for example a double-spool one. The turbomachine 1 comprises a first stage formed by a rotary fan 280 and a central gas turbine engine 130, located downstream of the rotary fan 280. Central to the turbomachine, the gas generator 130 comprises, from upstream to downstream in the direction of gas flow, a low-pressure compressor CBP1, a high-pressure compressor CHP1, a combustion chamber 160, a high-pressure turbine THP1 and a low-pressure turbine TBP1, which delimit a primary gas flow FP1.

[0037] The rotary fan 280 includes a set of rotary fan blades 2 extending radially outwardly from a rotary fan hub 250. The rotary fan blades 2 are externally surrounded by a fan housing 300, having one or more layers 301 of an abradable material on its surface opposite the blade tips 27 of the blades 2.

[0038] The turbomachine 1 has an upstream intake end 290 located upstream of the fan 280, and a downstream exhaust end 310. The turbomachine 1 also comprises an inter-vein casing 360 which delimits a primary vein in which circulates the primary flow FP1 which passes downstream of the fan 280 through the low pressure compressor CBP1, the high pressure compressor CHP1, the high pressure turbine THP1 and the low pressure turbine TBP1.

[0039] The inter-vein casing 360 comprises, from upstream to downstream, a casing 361 of the low pressure compressor CBP1, an intermediate casing 260, which is interposed between the low pressure compressor CBP1 and the high pressure compressor CHP1, a casing 362 of the high pressure compressor CHP1, a casing 363 of the high pressure turbine THP1 and a casing 190 of the low pressure turbine TBP1.

[0040] The CBP1 low pressure compressor and the CHP1 high pressure compressor can each have one or more stages, each stage being formed by a set of fixed blades (or stator blades) and a set of rotating blades (or rotor blades).

[0041] The fixed blades 101 of the low pressure compressor CBP1 are fixed to the casing 361. The rotary blades 102 of the low pressure compressor CBP1 are fixed to a first rotary transmission shaft 410.

[0042] The fixed blades 103 of the high pressure compressor CHP1 are fixed to the casing 362. The rotary blades 104 of the high pressure compressor CHP1 are fixed to a second rotary transmission shaft 400.

[0043] The THP1 high-pressure turbine and the TBP1 low-pressure turbine can each comprise one or more stages, each stage being formed by a set of fixed blades (or stator blades) and a set of rotating blades (or rotor blades).

[0044] The fixed blades 105 of the high pressure turbine THP1 are fixed to the casing 363. The rotating blades 106 of the high pressure turbine THP1 are fixed to the second rotating transmission shaft 400.

[0045] The fixed blades 107 of the low pressure turbine TBP1 are fixed to the casing 190. The rotating blades 108 of the low pressure turbine TBP1 are fixed to the first rotating transmission shaft 410.

[0046] The rotating blades 108 of the low-pressure turbine TBP1 drive the rotating blades 102 of the low-pressure compressor CBP1 to rotate about the axis AX under the effect of the thrust of the gases coming from the combustion chamber 160. The rotating blades 106 of the high-pressure turbine THP1 drive the rotating blades 104 of the high-pressure compressor CHP1 to rotate about the axis AX under the effect of the thrust of the gases coming from the combustion chamber 160.

[0047] The rotary fan blades 2 are upstream of the blades 101, 102, 103, 104, 105, 106, 107 and 108 and are of a different shape from them.

[0048] In operation, air flows through the rotary fan 280 and a first portion FP1 (primary flow FP1) of the air flow is routed through the low pressure compressor CBP1 and the high pressure compressor CHP1, in which the air flow is compressed and sent to the combustion chamber 160. The hot combustion products (not shown in the figures) from the combustion chamber 160 are used to drive the turbines THP1 and TBP1 and thus produce the thrust of the turbomachine 1. The turbomachine 1 also includes a secondary vein 390 which is used to pass a secondary flow FS1 of the air flow discharged from the rotary fan 280 around the inter-vein casing 360.More specifically, the secondary vein 390 extends between an inner wall 201 of a fairing 200 or nacelle 200 and the inter-vein casing 360 surrounding the central gas turbine engine 130, the fan casing 300 being the upstream part of this fairing 200 or nacelle 200. Arms 340 connect the intermediate casing 260 to the inner wall 201 of the fairing 200 in the secondary vein 390 of the secondary flow FS1.

[0049] Below, the rotary fan blade 2 of a turbomachine according to the invention is described with reference to the figures 4 to 17 .

[0050] To the figure 4 , the blade 2 comprises a body 20 made of a composite material, which extends between an upstream edge 22 and a downstream edge 23 distant from the upstream edge in the first longitudinal direction AX. The body 20 has a three-dimensional curvature in several plane sections taken perpendicular to the first longitudinal direction AX.

[0051] The body 20 made of composite material extends between an extrados 24 and a lower surface 25, distant from the extrados 25 along the second direction EP of thickness transverse to the first direction AX. The extrados 24 is turned outwards in the direction of rotation of the fan blade 2 when the fan hub 250 to which the blade root 26 is fixed rotates about the axial direction AX. The body 20 has a three-dimensional curvature in several plan sections taken perpendicular to the second direction EP of thickness. The extrados 24 is asymmetrical relative to the lower surface 25.

[0052] The body 20 made of composite material extends between a blade root 26 and the upper edge 27 of the blade head of the body 20, distant from the blade root 26 along the third height direction DR, transverse to the first and second directions AX and EP. The third height direction DR is oriented from bottom to top from the blade root 26 to the upper edge 27 of the blade head and to the metal part 27b of the blade head described below. The blade root 26 is used to be fixed to the longitudinal rotating hub 250 of the fan. For this purpose, the blade root 26 may have a thickened cross-section, which may for example be in the shape of a dovetail or other shape, along the direction EP relative to an intermediate zone 26b located between the blade root 26 and the upper edge 27 of the blade head. The blade root 26 can thus be inserted into a peripheral housing of the fan hub 250 to be fixed there.

[0053] An embodiment of the body 20 made of composite material is described below. The body 20 of the blade 2 is made of a composite material woven in three dimensions in a resin. The body 20 made of composite material comprises a resin matrix in which is embedded a fibrous reinforcement 4 comprising warp strands extending at least in the third height direction DR and weft strands extending at least in the first longitudinal direction AX in the finished state of the blade 2. A possible manufacturing method of the body 20 of the blade 2 is as follows. The warp strands are woven in three dimensions with the weft strands to form the fibrous reinforcement during a first weaving step.Then, during a second molding step, the fiber reinforcement is placed in a mold, where the fiber reinforcement is deformed according to a three-dimensional curvature imposed by a prescribed three-dimensional curvature of the interior walls of the mold, then resin is injected around the fiber reinforcement in the mold, to give the three-dimensional shape of the body 20 of the blade 2 in the finished state. After molding the resin around the fiber reinforcement, the warp strands and the weft strands have the three-dimensional curvature of the body 20 in the finished state. The fiber reinforcement 4 can be formed from a single-piece fiber preform obtained by three-dimensional or multi-layer weaving with evolving thickness. It comprises warp and weft strands which can in particular comprise carbon, glass, basalt, and / or aramid fibers. The matrix is ​​typically a polymer matrix, for example epoxy, bismaleimide or polyimide.The blade may be formed by molding using a resin vacuum injection process of the RTM (Resin Transfer Molding) type, or VARRTM (Vacuum Resin Transfer Molding). Three-dimensional weaving means that the warp strands follow sinuous paths in order to interconnect weft strands belonging to different weft strand layers except for gaps, it being noted that a three-dimensional weave, in particular an interlock weave, may include two-dimensional surface weaves. Different three-dimensional weave weaves may be used, such as interlock, multi-satin or multi-veil weaves.

[0054] Upstream of the upstream edge 22 is fixed, for example by gluing using a layer 7 of adhesive, a metal reinforcement part 3 (also called a shield) forming a leading edge 30 of the blade 2 ( figure 4 ). The reinforcement part 3 has the function of facing the aerodynamic flow entering in flight to address the problem of blade erosion and protection of the blade against bird ingestion.

[0055] A metal part 27b of the blade head of the metal reinforcement part 3 is described below with reference to the figures 5 to 17 .

[0056] The metal reinforcement part 3 comprises a metal upstream nose 31, which forms the leading edge 30 of the blade 2 and which is fixed to the upstream edge 22. The metal upstream nose 31 is formed of a first extrados flank 32b and a second intrados flank 33b, which connect to each other in the direction of the thickness direction EP and which end upstream at the leading edge 30. The metal reinforcement part 3 comprises a first fin 32, which is connected downstream of the first extrados flank 32b and which is fixed by the layer 7 of adhesive to an upstream part 28 of the extrados 24 of the body 2. The metal reinforcement part 3 comprises a second fin 33, which is connected downstream of the second intrados flank 33b and which is bonded by the layer 7 of adhesive to an upstream part 29 of the intrados 25 of the body 2.The metal upstream nose 31, the first fin 32 and the second fin 33 delimit a cavity in which the upstream edge 22 and the upstream parts 28, 29 of the extrados 24 and the intrados 25 are located. The metal upstream nose 31 is solid and is thicker than each fin 32 and 33 in the main zone 34 of the part 3. The body 20, the metal upstream nose 31, the first fin 32 and the second fin 33 have a three-dimensional curvature in first sections taken in several distinct planes perpendicular to the first direction AX, in second sections taken in several distinct planes perpendicular to the second direction EP and in third sections taken in several distinct planes perpendicular to the third direction DR.The part 3 ends along the third direction DE of height above its main zone 34 by a metal part 27b of blade head, located upstream of the first edge 27 of blade head of the body 2 made of composite material.

[0057] In reference to the figures 5 to 17, the upstream metal nose 31 comprises on the metal part 27b of the blade head one or more metal projection(s) 5 of prescribed wear. Each metal projection 5 of prescribed wear has a tapered thickness EP5 in the first longitudinal direction AX and a determined non-zero height H in the third height direction DR. The metal projection(s) 5 of prescribed wear is delimited by one or more recesses 4, which is / are of tapered thickness in the first longitudinal direction AX and which are arranged at least on the metal part 27b of the blade head of the upstream metal nose 31. The metal projection(s) 5 of prescribed wear is configured to detach at least partially in the presence of tangential friction going in the second thickness direction EP against the metal part 27b of the blade head.The recess(es) 4 and the prescribed wear metal projection(s) 5 extend upstream the first metal fin 32 and / or the second metal fin 33 and / or the upstream edge 22 of the body 21 made of composite material. The projection 5 thus acts as a fuse in the event of excessive contact with the abradable material 301 located on the casing 300 of the fan 280. The prescribed breakage projection 5 is present in a self-engaging part of the blade 2, that is to say a part that can come into contact with the abradable material 301 of the casing 300 of the fan 280, as defined above. Thus, in the event of significant force on the metal part 27b of the blade head, due to contact with the abradable 301, the projection 5 will partially detach from the blade, which makes it possible to directly exit contact with the abradable 301 and will avoid self-engagement.The dimensions of the projection 5 can be determined based on the dimensions of the parts of the blade closest to the abradable 301. The projection 5 forms a thinning of the metal part 27b of the blade head.

[0058] In reference to the figures 5 to 17 , the recess(es) 4 has the determined non-zero height H above the main part 34 and is delimited downwards by a transition surface 8 connecting the projection 5 to the main part 34 of thickness EP34 greater than the thickness EP5 of the projection 5. The transition surface 8 faces upwards in the third height direction DR and may have, for example, a break 9 in slope or edge 9 connecting it to the main part 34 and / or to the projection 5.

[0059] According to embodiments of the invention according to the figures 5 to 12, the longitudinally tapered thickness EP5 of the prescribed wear metal projection 5 is constant at least over a portion of the determined height H starting from the top. Thus, this portion of the height of the prescribed wear metal projection 5 does not offer increasing resistance during friction against the abradable material 301 of the fan casing 300 in the event of the start of self-engagement during rotation of the blade 2 and wears more easily, which reduces the risks of self-engagement and makes it possible to achieve the second objective indicated above.

[0060] In the embodiment of the invention shown in figures 5 , 6 And 9 , the longitudinally tapered thickness EP5 of the prescribed wear metal projection 5 is constant over the entire determined height H. The transition surface 8 may be flat and for example perpendicular to the projection 5.

[0061] In the embodiment of the invention shown in figures 7 to 10 , the longitudinally tapered thickness EP5 of the prescribed wear metal projection 5 is constant over an upper part 51 of the height H.

[0062] The transition surface 8 may be curved (e.g. concave) in several plane sections, which are taken perpendicular to the first longitudinal direction AX as to the figures 7 to 10 The transition surface 8 may form a fillet 42 and / or 43 or a shoulder 42 and / or 43 facing upwards.

[0063] To figures 4 to 10 , a first recess 4 may thus be provided formed by a first curved shoulder 42 connected to the first extrados flank 32b of the upstream metal nose 31 and / or a second recess 4 formed by a second curved shoulder 43 connected to the second intrados flank 33b of the upstream metal nose 31.

[0064] In other embodiments not shown, the projection 5 may be located on the side of the first extrados flank 32b of the upstream metal nose 31, the recess 4 being in this case on the side of the second intrados flank 33b of the upstream metal nose 31. In other embodiments not shown, the projection 5 may be located on the side of the second intrados flank 33b of the upstream metal nose 31, the recess 4 being in this case on the side of the first extrados flank 32b of the upstream metal nose 31.

[0065] In the embodiment of the invention shown in figures 5 to 17, the longitudinally tapered thickness EP5 of the prescribed metal wear projection 5 is constant over a major portion 311 of a length of the metal upstream nose 31 in the longitudinal direction AX. For example, the major portion 311 of the length of the metal upstream nose 31 in the longitudinal direction AX represents at least 50% of the length of the metal upstream nose 31 in the longitudinal direction AX. The length of the metal upstream nose 31 in the longitudinal direction AX is taken between the leading edge 30 and the upstream edge 22, or between the leading edge 30 and the first metal fin 32, or between the leading edge 30 and the second metal fin 33.

[0066] In the embodiment of the invention shown in figure 9, the metal part 27b of the blade head and / or the prescribed metal wear projection 5 has the thickness EP5 increasing in the direction from upstream to downstream along the longitudinal direction AX. The recess(es) 4 is delimited by the edges 9 of the metal upstream nose 31. The thickness e1, e2 occupied by the at least one recess 4 relative to the edges 9 increases in the direction from upstream to downstream along the longitudinal direction AX over a major part 311 of the length of the metal upstream nose 31. We thus have e1 < e2 with the thickness e1 taken further upstream than the thickness e2. The major part 311 can have the definition mentioned above.

[0067] In the embodiments of the invention shown in figures 1 to 17, the first edge 27 of the blade head of the body 2 made of composite material may have another thickness increasing in the direction from upstream to downstream along the longitudinal direction AX over an upstream portion, for example over at least 20% or at least 50% starting from the upstream edge 22, of the length of this first edge 27 of the blade head, taken along the longitudinal direction AX. The length of this first edge 27 of the blade head may be taken along the longitudinal direction AX between the upstream edge 22 and the downstream edge 23 of the body 20 made of composite material.

[0068] In the embodiment of the invention shown in figures 7 , 9 and 10, the determined non-zero height H, h1, h2 occupied by the recess(es) 4 and by the projection 5 relative to the edges 9 decreases in the direction going from upstream to downstream following the longitudinal direction AX over a major part 311 of the length of the upstream metal nose 31. We thus have h1 > h2 with the height h1 taken further upstream than the height h2. The major part 311 can have the definition mentioned above.

[0069] In the embodiment of the invention shown in figure 11, the prescribed wear metal projection 5 surrounds the recess(es) 4. The projection 5 comprises two first and second longitudinally tapered parts 51 and 52, which extend in the DR direction of the height respectively the first extrados flank 32b of the upstream metal nose 31 and the second intrados flank 33b of the upstream metal nose 31. The recess 4 is delimited between the longitudinally tapered parts 51 and 52 and above a bottom 40 located between these longitudinally tapered parts 51 and 52. This makes it possible to maintain the aerodynamic profile of the blade, the external surfaces being unchanged. The recess 4 may be a hollow, which can be produced by machining.

[0070] In the embodiment of the invention shown in figures 12 to 17, the blade head edge 27 comprises another prescribed wear projection 6 (or second prescribed wear projection 6), which is of tapered thickness in the longitudinal direction AX and which extends downstream the prescribed wear metal projection 5 (or first prescribed wear metal projection 5) in the longitudinal direction AX. The other prescribed wear projection 6 is therefore made of the composite material of the body 20 of the blade 2. The other projection 6 forms a thinning of the blade head edge 27. The other projection 6 thus acts as a fuse in the event of excessive contact with the abradable 301 located on the casing 300 of the fan 280. The other prescribed breaking projection 6 is present in a self-engaging part of the blade 2, that is to say a part which can come into contact with the abradable material 301 of the casing 300 of the fan 280, as defined above.Thus, in the event of a significant force on the edge 27 of the blade head, due to contact with the abradable 301, the other projection 6 will partially detach from the blade, which makes it possible to directly exit contact with the abradable 301 and will avoid self-engagement. The dimensions of the other projection 6 can be determined based on the dimensions of the parts of the blade closest to the abradable 301.

[0071] The other prescribed wear projection 6 may be bordered by a chamfer 61 extending in the longitudinal direction AX and connected to the intrados 25 (or to the extrados 24 in other embodiments not shown), as illustrated in figures 12 , 13 and 14 at 17. Chamfer 61 may be flat.

[0072] The other 6 may end upwards with a flat surface 62, which is tapered along the longitudinal direction AX and which has a non-zero thickness EP62 as shown in figures 12 And 15 à 17 .

[0073] The chamfer 61 may extend over a portion of the length of the blade head edge 27 starting from its upstream edge 22, as shown in figure 17 (where the adhesive layer 7 has not been shown), to form a local chamfer 61.

[0074] The other 6 may end upwards with an edge 63, which extends in the longitudinal direction AX and which has zero thickness as shown in figure 13 .

[0075] The other 6 may end upwards with a rounded edge 64, which extends in the longitudinal direction AX and which is connected to the intrados 25 and to the extrados 24, as shown in figure 14 The rounded edge 64 has, in several distinct planes transverse to the AX direction, a radius of curvature smaller than that of the intrados 25 and the extrados 24.

[0076] Of course, the embodiments, features, possibilities and examples described above can be combined with each other or selected independently of each other.

Claims

1. A rotary turbomachine fan blade (2), the blade (2) comprising: a body (20) made of a composite material, having an upstream edge (22) and a downstream edge (23), between which the body (20) extends along a first longitudinal direction (AX), an extrados (24) and an intrados (25), between which the body (20) extends along a second thickness direction (EP), which is transverse to the first direction (AX), a blade root (26) and a blade head edge (27), between which the body (20) extends along a third height direction (DR), transverse to the first and second directions (AX, EP), the blade root (26) having the function of attachment on a longitudinal rotary fan hub (250), a metallic reinforcement part (3) comprising an upstream metallic nose (31), which forms a leading edge (30) of the blade and which is fixed to the upstream edge (22), a first metallic fin (32), which is connected downstream of a first extrados flank (32b) of the upstream metallic nose (31) and which is fixed to an upstream portion (28) of the extrados (24), and a second metallic fin (33), which is connected downstream of a second intrados flank (33b) of the upstream metallic nose (31) and which is fixed to an upstream portion (29) of the intrados (25), the upstream metallic nose (31) having a metallic blade head portion (27b), located upstream of the blade head edge (27), the upstream metallic nose (31) comprising at least on the metallic blade head portion (27b) at least one recess (4), which is of longitudinally tapered thickness (AX) and which is opening out along the third height direction (DR) on the metallic blade head portion (27b), the blade being characterized in that the at least one recess (4) delimits on the metallic blade head portion (27b) over a determined non-zero height (H) along the third height direction (DR) at least one metallic prescribed wear protrusion (5), which is of longitudinally tapered (AX) thickness (EP5) over a major portion (311) of a length of the upstream metallic nose (31) along the first longitudinal direction (AX) and which is configured to be detached at least partially in the presence of tangential friction in the second thickness direction (EP) against the metallic blade head portion (27b), the at least one recess (4) and the at least one metallic prescribed wear protrusion (5) extending, in the first longitudinal direction (AX) upstream, the first metallic fin (32) and / or the second metallic fin (33) and / or the upstream edge (22) of the body (20) made of a composite material.

2. The blade according to claim 1, characterized in that the longitudinally tapered (AX) thickness (EP5) of the metallic prescribed wear protrusion (5) is constant at least over a portion (51, H) of the determined non-zero height (H).

3. The blade according to claim 1, characterized in that the longitudinally tapered (AX) thickness (EP5) of the metallic prescribed wear protrusion (5) is constant over a major portion (311) of the length of the upstream metallic nose (31).

4. The blade according to any one of the preceding claims, characterized in that the metallic blade head portion (27b) has a thickness (EP5) increasing from upstream to downstream, the at least one recess (4) is delimited by ridges (9) of the upstream metallic nose (31), wherein the thickness (e1, e2) occupied by the at least one recess (4) relative to the ridges (9) increases from upstream to downstream over the major portion (311) of the length of the upstream metallic nose (31).

5. The blade according to any one of the preceding claims, characterized in that the metallic blade head portion (27b) has a thickness increasing from upstream to downstream, the at least one recess (4) is delimited by ridges (9) of the upstream metallic nose (31), wherein said determined non-zero height (H, h1, h2) occupied by the at least one recess (4) relative to the ridges (9) decreases from upstream to downstream over a major portion (311) of the length of the upstream metallic nose (31).

6. The blade according to any one of the preceding claims, characterized in that the at least one recess (4) is formed by at least one shoulder (42), which is connected to the first extrados flank (32b) of the upstream metallic nose (31).

7. The blade according to any one of the preceding claims, characterized in that the at least one recess (4) is formed by a shoulder (43), which is connected to the second intrados flank (33b) of the upstream metallic nose (31).

8. The blade according to any one of claims 1 to 5, characterized in that the upstream metallic nose (31) comprises as a recess (4) at least a first recess (42), which is formed by a first shoulder (42) connected to the first extrados flank (32b) of the upstream metallic nose (31), and at least a second recess (43), which is formed by a second shoulder connected to the second intrados flank (33b) of the upstream metallic nose (31).

9. The blade according to any one of claims 6 to 8, characterized in that the shoulder (42, 43) is curved.

10. The blade according to any one of claims 1 to 5, characterized in that the metallic prescribed wear protrusion (5) surrounds the at least one recess (4).

11. The blade according to any one of claims 1 to 5, characterized in that the blade head edge (27) comprises another metallic prescribed wear protrusion (6), which is of longitudinally tapered thickness (AX) and which extends the at least one metallic prescribed wear protrusion.

12. A rotary turbomachine fan (280), comprising a longitudinal rotary fan hub (250) and a plurality of blades (2) according to any one of the preceding claims, which are fixed by their blade root (26) to the longitudinal rotary fan hub (250).

13. A turbomachine (1) comprising a rotary fan (280) according to claim 12, and, downstream of the fan (280), a low-pressure compressor (CBP1), a high-pressure compressor (CHP1), a combustion chamber (160), a high-pressure turbine (THP1) and a low-pressure turbine (TBP1).