BE1030761B1 - BLADE FOR TURBOMACHINE STATOR - Google Patents

Abstract

The invention proposes a blade (9; 109) with variable pitch of a turbomachine stator, the blade comprising: a blade (11) for guiding an air flow; and one or two platforms (26) arranged at one end or both ends of the blade, the platform(s) comprising a surface for guiding the air flow (26.1), the surface comprising a first portion disc (30.1) on the intrados side (11.3) and a second disc portion (30.2) on the extrados side (11.4); remarkable in that the or at least one of the first or second disc portions comprises a bump (32).

Description

‘ BE2022/5620

Description

TURBOMACHINE STATOR FURNACE BLADE

Technical area

The invention concerns turbomachine stator blades and more particularly the design of variable pitch blades with surface contouring,

Prior art

Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft but also to those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

Technological research efforts have already made it possible to very significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impacting factors in all phases of design and development to obtain aeronautical components and products that consume less energy, more environmentally friendly and whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

Consequently, the Applicant is constantly working to reduce its negative climate impact through the use of methods and the exploitation of virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the Minimum possible for reduce the environmental footprint of its activity.

This sustained research and development work concerns both new generations of aircraft engines, the lightering of aircraft, in particular through the materials used and lightweight on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, essential complements to technological progress, aeronautical biofuels.

In this context, the invention relates more particularly to aspects related to aircraft turbomachine compressors. Compressors include stator vanes for straightening a primary flow, or “rectifier”. The air flow may present unwanted secondary flows, due in particular to separation at the upper surface and lower surface, which has negative consequences on the performance of the compressor Impacting the efficiency of the turbomachine

The published patent document WO 2019/228897 A1 discloses blades of a rectifier extending from a non-axisymmetric surface commonly called "3D contouring", the latter includes hollows and bumps aimed at limiting the appearance secondary flows.

However, this solution aimed at providing the rectifier shrouds with hollows and/or bumps is not suitable for variable-pitch vanes (or “VSV” for “Variable Slator Vans”). Indeed, if the design of hollows and/or bumps on the shroud are optimized for a given direction of the air flow, the variations in the speed and/or direction of the flow resulting from the pivoting of the VSV blades make the contouring suboptimal, For example, we note the appearance of “horseshoe” vortices for VSV blades at high incidence.

The contouring proposed by document WO 2019/228897 AT only concerns fixed rectifier blades and therefore does not make it possible to effectively limit the appearance of secondary flows at the level of a rectifier with variable timing.

Summary of the invention

Technical problems

The invention aims to solve at least one of the problems posed by the prior art. More precisely, the invention aims to propose a blade which guarantees stability in order to limit intrinsic efficiency pearls and to guarantee good efficiency of the compressor of an urban machine independently of the incidence of the VSV blades.

Technical solution

The invention is the result of technological research aimed at very significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of aircraft. For this, the present invention relates to a blade with variable pitch of a turbomachine stator, the blade comprising: - A blade for guiding an air flow, the blade having a leading edge and a leading edge trailing edge, as well as an intrados and an extrados extending from the leading edge to the trailing edge; and - One or two platform(s) arranged at one end or at both ends of the blade, the platform(s) comprising a surface for guiding the air flow, the surface comprising a first disc portion on the side of the intrados and a second disc portion on the extrados side; remarkable in that ia or at least one of the first or second disc portions comprises a bump,

Advantageously, the platform allows the blade to be fixed in a casing of the turbomachine, preferably by means of a pin ensuring a pivot connection with the casing.

Preferably, the blade comprises a single platform arranged at the head of the blade. More preferably, Vaube comprises two platforms, one at the head of the blade and the other located at the foot of said blade.

The platform(s) comprises two disc portions, the latter two are preferably seen in a racial direction. To this end, it should be noted that the discs are asymmetrical because their air curving surface n It is not flat (includes one or two bumps).

According to an advantageous mod of the invention, the or V at least one of the first disk portions comprises a first boss, and the top of said first boss has a position whose projection on the chord line of the blade to the right of the platform is 10% or less from the leading edge of the rope.

According to an advantageous embodiment of the invention, the top of the first boss is attached to the lower surface or is arranged at a distance from said lower surface of between 0% and 30% of a maximum thickness of the blade.

According to an advantageous embodiment of the invention, the or at least one of the second disc portions comprises a second bump.

Advantageously, the second bump makes it possible to delay or even avoid the stalling of the air flow at the level of the upper surface of the blade,

Preferably, the top of the second boss comprises a position whose projection on the chord of the blade to the right of the platform is distant from the trailing edge of the blade by a distance corresponding to 10% or less of the chord.

According to an advantageous embodiment of the invention, the platform comprises a peripheral edge which intersects the radial projection of the extrados on the rigging surface at a rear intersection point, the top of the second boss having a position whose projection on the line of chord of the blade to the right of the platform is at a distance from the projection of the rear intersection point on the chord which is less than or equal to 10% of the chord.

According to an advantageous embodiment of the invention, apart from the bump(s), the surface of the first and the second disk portion is substantially flat, and the top of the bump(s) rises above the substantially flat surface. with a height which is between 0.5 and 5 mm, preferably between 1 and 3 mm,

According to an advantageous embodiment of the invention, the height of the top of the first boss is between 0.1 and 0.3 times the maximum thickness of the blade or between 1 and 3 times said maximum thickness, or the height of the top of the blade. second bump are! between 0.1 and 0.3 times the maximum thickness of the blade or between 1 to 3 times said maximum thickness.

Advantageously, this height of the bumps makes it possible to minimize secondary flows, while limiting the impact of said bumps on the serodynamic profile of the blade. Indeed, if the height of the bumps is too great, then a blockage of the air flow may occur. 5 According to an advantageous embodiment of the invention, the height of the top of the bump(s) is between 1% and 10% of the rope.

According to an advantageous embodiment of the invention, the bump(s) are at a distance from the peripheral edge.

Advantageously, the first bump and/or the second bump are here confined on the platform and do not extend over the fixed part of the carrier, because in the case where the bump(s) are on a fixed part (casing of turbomachine) outside the platform, the homogeneity of the aerodynamic flow risks being impacted. Indeed, the confinement of the bumps on the platforms of the blades of the invention allows said bumps to act on the secondary flows whatever or the incidence of the blade.

According to an advantageous embodiment of the invention, the first boss has a main orientation which forms an angle of between 30° and 60° with the chord of the blade.

Preferably, the main orientation of the first bump corresponds to a direction or a main axis of the extent of said first bump on the plaisform. To this end, the main orientation defines the direction of the largest dimension of said first bump. The main axis is preferably substantially parallel to the guiding surface of the platform and can be seen radially,

According to an advantageous embodiment of the invention, the second bump has a truncated cardioid shape.

The invention also relates to an aircraft turbomachine comprising a compressor, said compressor comprising a surface for guiding a substantially axisymmetric air flow with the exception of an annular row of housings, the turbomachine being remarkable in this that it comprises an annular row of blades according to the invention and one of its advantageous modes mentioned above, the platforms of the blades being received in housings of the casing such that the air guiding surfaces of the platforms are substantially flush with the air flow guide surface of the crankcase,

Advantageously, the blade of the invention makes it possible to avoid the appearance of secondary flows at the level of the stator rectifier with variable timing 5 of a compressor of the turbomachine.

Indeed, the first bump makes it possible to limit or even prevent an undesirable secondary flow from rising towards the exirados of a neighboring blade in a row of stator blades of the compressor. At the same time, the second bump makes it possible to better guide the air flow in contact with the upper surface and to avoid its id — separation of said upper surface.

Furthermore, the invention is particularly advantageous because it makes it possible to improve the performance of aircraft compressors and the overall efficiency of turbomachines, which results in a reduction in fuel consumption and greenhouse gas emissions, thus reducing the environmental impact of aircraft. it is understood that each detail of an embodiment below may be combined with each other detail of the other embodiments.

Brief description of the drawings

Figure 1 illustrates a sectional view of a compressor of an axial turbomachine;

Figure 2 shows a perspective view of a blade according to the invention;

Figure 3 illustrates a radial view of the blade according to a first embodiment of the invention:

Figure a illustrates a side view of the blade of Figure 3;

Figure 5 illustrates a radial view of a blade according to a second embodiment of the invention;

Figure 6 illustrates a side view of the blade of Figure 5;

Figure 7 illustrates a radial view of a blade according to a third embodiment of the invention,

Detailed description of the embodiments

In the description which follows, the terms “Internal”, “inner”, “lower”, “external” and “upper” refer to positioning by contribution to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine, the lengths stan! measured axially. The widths are measured according to the circumference, The radial direction is perpendicular to the axis of rotation. Upstream and Vaval refer to the main flow direction of the air flow in the turbomachine.

The dimensions of the figures are not to scale and in particular the thicknesses or radial dimensions are exaggerated to facilitate the reading of the figures.

Figure 1 represents a sectional view of a compressor 2 of an axial turbomachine 4.

The turbomachine A can correspond to a double-flow turbojet, a furboiet, turbofan, turboprop, turboshaft or any other double-flow turbine, is Alternatively, the turbomachine 4 can correspond to a multi-flow turbomachine, such as a triple-flow turbojet non-ducted flow (CROR “Counter-Rotating

Open Rotor” or USF “Unducted Single Fan”}, or any other tripe-flux turbomachine.

Preferably, the compressor 2 corresponds to a low-pressure compressor 2 or to a high-pressure compressor (not shown). The turbomachine 4 further comprises other components not shown in Figure 1, such as a high-pressure compressor, a combustion chamber and one or more levels of turbines. In operation, the mechanical power of the turbine transmitted via the central shaft to rotor 8 sets the two compressors in motion. The latter comprise several rows of rotor blades 8 associated with rows of stator blades 10. The rotation of the rotor 6 around its axis of rotation 'at the entrance to the combustion chamber.

A fan 12 (partially Hlustrated), is coupled to the rotor 6 and generates an air flow which is divided into a radially internal flow F1, commonly called primary flow F1, and into a radially external flow F', which can correspond to a flow secondary F' in the context of a double-flow turbomachine, or to a tertiary flow FP' of a turbomachine 4 of the fripie-flux type.

The radially external flow F' passes through an annular conduit (partially shown). The secondary flow is accelerated to generate a thrust reaction useful for the flight of an aircraft, The primary flow F1 and radially external = are both annular and separated by a separation nozzle 14,

It can be seen in Figure 1 that the rotor 12 comprises several rows of fotoric vanes 8, in this case three, and several rows of stator vanes 10, in this case three; the latter make it possible to convert the speed of the air flow io F1 into pressure, in particular into static pressure.

The rotor blades 8 can extend radially from a rotor support 16 which can be a dovetail platform, an internal crown of a one-piece bladed drum or any other type of support for a composite rotor,

The stator vanes 10 extend essentially racially from an exterior casing 18. They can be fixed there and immobilized using fixing pins 20. They pass radially through the primary flow F1. The stator vanes can be fixed chord (radially constant) relative to the outer casing 18,

The low-pressure compressor 2 comprises, at the inlet of a primary flow stream 22 F1, a row of siatoric straightening vanes 9 with variable pitch.

Preferably, the variable pitch of the blades 9 es! ensured by means of an actuation system (unpolished) regulating the angle formed by the blades 11 of the blades 9 around an axis 24,

In this configuration, each blade 9 comprises a blade 11 as well as one or preferably two platforms 26 which are substantially circular and arranged at both ends of the blade 11. Each platform 25 is provided with a pin 28, on the side opposite the blade 11 and ensuring a pivot connection with the exterior casing 18 or interior 30, The exterior casing 18 is delimited radially internally by an upper surface 18.1 for guiding the primary flow F1,

and the interior casing 30 is delimited radially externally by an interior guide surface 30.1,

Advantageously, the blades 11 of the rectifier are identical and annularly aligned.

The casing 18, 30 comprises housings 31 distributed annularly around the axis X and in which the platforms 26 are housed and pivotally mounted.

Advantageously, the platforms 26 comprise axisymmetric air guide surfaces 26.1 (circular, cylindrical, conical, etc.) substantially flat and flush with the air flow guide surfaces 18.1 and 30.1 of the casing 18, 30, Appropriate seals can guarantee the seal between the platforms 26 and the casing,

Figure 2 represents a perspective view of a blade 9 according to the invention. The blade 11 of the blade 9 comprises a leading edge 11.1 and a trailing edge 11.2, as well as an intracos 11.3 and an extrados 11.4 extending from the leading edge 11.1 to the trailing edge 11.2.

The blade 11 further comprises a chord line LC, a skeleton line S and a maximum thickness e (illustrated in Figure 3).

The guide surface 26.1 of the platform 25 comprises a first disk portion 30.1 on the intrados side 11.3 and a second disk portion 30.2 on the extrados side 11.4.

The separation between the first 30.1 and the second disk portion 30.2 preferably corresponds to the extension of the skeleton line S or the camber line S of the blade 11 on the guide surface 25.1 (seen radially).

According to a first embodiment of the invention, the first portion 30.1 comprises a first bump 32. Details on the shape and position of the first bump 32 will be detailed later in the present description.

Figure 3 illustrates a radial view of the blade 9 according to the first embodiment of the invention,

We can see contour lines (iso-contour illustrating the first bump 32 comprising a vertex 34 having a projection 34.1 on the chord line LC of the blade 11 which is preferably distant from the leading edge 11.1 by a distance D1 corresponding to at most 10% of the chord ©. Alternatively, the distance D1 can be greater without however exceeding 15% of the chord ©.

Preferably, the top 34 of the first boss 32 is arranged adjacent (substantially abutting) to the lower surface 11.3. However, the top 34 can be in the vicinity of the intrados 11.3, Le, arranged at a distance between 0% and 50% of the maximum thickness e, and preferably between 0% and 30%.

More preferably, the top 34 is at most 3 mm from the intrados 11.3.

Advantageously, such an arrangement of the first bump 32 makes it possible to have a direct impact on the "horseshoe" vortex, because it makes it possible to avoid the separation of the boundary layer at the level of the wall of the blade on the side intrados 11.3 and/or extrados 11.4,

The first bump 32 comprises a substantially circular or oval or elliptical shape, said bump 32 being preferably substantially elliptical.

However, the shape of the bump 32 can be truncated by the intrados 11.3. The first bump 32 comprises a main orientation H illustrated by a main axis 32.1 which can form an angle of between 30° and 80° with the chord line LC, and preferably an angle of approximately 45° (110%) with the chord line LC,

Indeed, an orientation of the first bump 32 at 0° relative to the rope line LC does not make it possible to obstruct secondary flows, and an orientation at 90° with the rope line LG does indeed obstruct unwanted flows, but generates superior aerodynamic pearls.

Advantageously, the orientation of the first bump 32 as well as the position of the vertex 34 makes it possible to obstruct the horseshoe vortex in order to avoid its passage towards Vexirados 11.4, and this, in all possible orientations of the blade D around its axis 24, To this end, the blade 9 ensures optimal operation of the aircraft compressor in all flight conditions,

Figure 4 illustrates a side view of the blade 9 of Figure 3. here the blade 9 is partially illustrated, in particular a lower half of said blade 9 is shown, and the dotted line can possibly correspond to an axis of symmetry of dawn 9.

We see that the top 34 of the first bump 32 rises above the substantially flat surface 26.1 by a height H1,

Preferably, the height Hi of the top 34 is between 1% and 10% of the chord of the blade 11.

The height H1 is determined as a function of the maximum thickness e (shown here in Figure 3) of the blade 11 to the right of the platform 26 (that is to say that in cases where the thickness of the blade 9 is not constant on its radial height, the height of the bump is defined in relation to the maximum thickness), In fact, it is preferable that the height Hi is between 0.1 and 3 times the thickness maximum e. More preferably, the height H1 is between 0.1 and 0.3 times the maximum thickness e when the first boss 32 is at the blade head, and between 1 and 3 times the thickness e when said boss 32 is at the root dawn.

For this purpose, the height H1 can, for example, correspond to 1 mm when the thickness e is equal to 10 mm, particularly in the case where the first boss 32 is on the platform at the blade head, or said height H1 can be equal to 3mm if the thickness e is 1 mm, particularly in the case where the first bump 32 is on the platform at the base of the blade.

Preferably, the height H1 is between 0.5 and 5 mm, and more preferably between 1 and 3 mm. Below this interval {HT height less than 1 mm), the tolerances of the shape of the first bump 32 can affect the effectiveness of the latter in slowing down secondary flows. At the same time, beyond this interval (height H1 greater than 3 mm), the performance of the compressor at nominal incidence risks being degraded.

The first bump 32 may have a generally convex and/or concave shape. Preferably, the first bump 32 has a convex shape at an upstream part corresponding to approximately half of the extent of said bumps 32 (here the term approximately corresponds to 120% of the extent), said first bump 32 has a concave shape on a downstream part corresponding to another half, and more preferably, the convex half is arranged downstream of the bump 32 (closer to the trailing edge 11.2} so as to arrange the convex part in direct contact with the secondary flows to block them and allow the flow downstream to be better guided with the concave half,

Figure 5 illustrates a radial view of a blade 109 according to a second embodiment of the invention, in which the blade 109 comprises a second boss 19 132 to the right of the second disk portion 30.2 of the surface 26.1.

The identical elements between the first and second embodiments have the same reference signs, while the additional or substantially similar elements are incremented by 100,

Preferably, the blade 109 comprises the first leg 32 to the right of the first disk portion 30.1 and the second boss 132 arranged to the right of the second disk portion 30.2.

The platform 26 comprises a peripheral edge 25.2, and the first 32 and the second bump 132 are at a distance from said peripheral edge 26.2. This allows the 3D contour to rotate entirely with the 103 blade.

The upper surface 11.4 has a rear intersection point 11.5 with the platform 26, and precisely with the peripneral edge 26.2, said point 11.5 corresponds to an intersection between said peripheral edge 26.2 and the radial projection of

Vextrados 11.4 on the guide surface 295.1, For this purpose, the rear intersection point 11.5 is located downstream of the platform 26 (close to the trailing edge 11.2 of the blade 11), and the second bump 132 comprises a vertex 134 whose projection 134.1 on the chord line LC is distant by a distance D2 relative to a projection 11.6 of the rear intersection point 11.5 on the chord line LC .

Preferably, the distance D2 corresponds to at most 15% of the chord ©, and more preferably, the distance D2 corresponds to 10% or less of the chord ©.

In an alternative not shown, the vertex 134 can be positioned so that its projection 134.1 on the chord line LC is distant from the leading edge 11.1 by a distance D1 corresponding to at least 10% of the chord ©.

The top 134 is attached to the extrados 11.4 or arranged at a distance from said extrados 11.4 of between 0% and 50%, and preferably between 0% and 30% of the maximum thickness e, similar to the arrangement of the top 34 of the first boss 32 relative to the intrados 11.3.

Advantageously, such an arrangement of the second bump 132 makes it possible to delay or even avoid the separation of the boundary layer at the level of the wall of the blade on the exirados side 11.4,

In this configuration, the first bump 32 acts directly on the "horseshoe" vorlex phenomenon so as to limit its impact, and the second bump 132 makes it possible in a curative manner to compensate for stalls that may be caused to the right of the extrados 11.4 by the phenomenon.

Preferably, the second bump 132 comprises a truncated cardioid shape, or a substantially circular, or oval, or elliptical shape, said second bump 132 being preferably in the shape of a truncated cardioid with a main orientation substantially parallel to the extrados 11.4, of so that the second bump 132 extends in its main direction which follows the curvature of the extrados 11.4. In fact, the second bump 132 follows the contour of the extrados 11.4 so as to be able to better guide the flow of air and avoid its separation from said extrados 11.4,

Figure 6 illustrates a side view of the blade 109 of Figure 5. We see that the top 134 of the second boss 132 rises above the substantially flat surface 26.1 by a height Hz.

Preferably, the height H2 of the vertex 134 is determined as a function of the maximum thickness e similarly to the height H1 of the first bump 32. For this purpose, the height HZ is between 0.1 and 3 times the thickness e, and more preferably between 0.1 and 0.3 times the maximum thickness e when the second boss 132 is at the tip of the blade, and between 1 and 3 times the thickness e when said bump 132 is at the tip of the blade.

The height H2 can, for example, correspond to 1 mm when the thickness e is equal to 10 mm, particularly in the case where the second boss 132 is located on the platform at the blade head, or said height H2 can be equal to 3 mm if the thickness e is 1 mm, particularly in the case where the second boss 132 is located on the platform at the base of the blade.

However, it should be noted that on the same substantially flat surface 26.1, the height H2 is preferably less than the height HT. id Preferably, the height H2 is between 1% and 10% of the chord of the blade 11. More preferably, the height H2 is between 0.5 and 5 mm, and more preferably between 1 and 1 mm,

The second bump 132 may have a generally convex and/or concave shape. Preferably, the second bump 132 has a convex shape at an upstream part corresponding to approximately half of the extent of said second bump 132 (here the term approximately corresponds to 120% of the extent), said second bump 132 has a concave shape on a part avai corresponding to another half, and more preferably, the convex half is arranged downstream of the bump 132 {closer to the edge of leak 11.2} so as to allow better guidance of the air flow downstream.

Figure 7 illustrates a radial view of a blade 209 according to a third embodiment of the invention, in which the substantially flat surface 26.1 of the blade 209 comprises only the second boss 132 to the right of the second disk portion 30.2 .

Indeed, the blade 209 according to the third embodiment, is devoid of the first bump 32 (flustered in Figures 1-6), In this configuration, during high incidences, the second bump 132 makes it possible to maintain a flow of the air flow on the upper surface 11.4 in order to avoid its separation which could be caused by a horseshoe vortex.

It is understood that the three embodiments of Figures 3, 5 and 7 can be combined on the same blade: a blade can have a bump on the intrados side at the root and a bump on the extrados side at the head (or vice versa), or have two bumps on one of its platforms and none on another.

Also, different blades of the same row of blades can have one and/or the other of the configurations of the three illustrated embodiments.

Claims (1)

Claims 1. Blade (9; 108) with variable stator timing of the turbomachine (4) of Seronet, the blade {98; 109) comprising: - a blade (11) for guiding an air flow, the blade (11) having a leading edge {11.7} and a trailing edge (11.2), as well as an intrados (11.3) and an extrados {14.4) extending from the leading edge (11.1) to the trailing edge {11.2}; and - one or two platform(s) (26) arranged at one end or at both ends of the pals (11), the platform(s) (25) comprising a guiding surface (26.1) of the air flow , the surface (26.1) comprising a first disc portion (30.1) on the intrados side (11,3) and a second disc portion (30.2) on the extrados side {11,4}; characterized in that where at least one of the first (30.1) or second disc portions (30.2) comprises a bump (32,132). is 2. Blade (9; 109) according to claim 1, characterized in that the or at least one of the first disc portions (30.1) comprises a first boss (32), and the top (34) of said first boss ( 32) has a position whose projection {34.1} on the chord line (LG) of the blade (9; 109) to the right of the platform (26) is distant from the leading edge (11.1) by 10 % or less of the chord (C). 3, blade (9; 109) according to one of the preceding claims, characterized in that the top (34) of the first boss (32) is attached to the intrados (11,3) where is arranged at a distance from said intrados (11.3) between 0% and 30% of a maximum thickness (e) of the blade (11). 4. Blade (109) according to one of the preceding claims, characterized in that the or at least one of the second disc portions (30.2) comprises a second boss (132). 5. Blade (108) according to claim 4, characterized in that the platform {26} comprises a peripheral edge (26.2) which intersects the racial projection of the extrados {1 1,4) on the guide surface (26.1 ) at a rear intersection point (11.5), the apex (134) of the second boss (132) having a position whose projection (134.1) on the chord line (LG) of the blade (109) to the right of the platform (26) is at a distance (D2) from the projection (11.6) of the rear intersection point (11.5) on the chord line (LG) which is less than or equal to 10% of the chord ( C3. 8. Blade (8; 109) according to one of claims 4 or 5, characterized in that, apart from the bump(s) (32; 132), the surface (26.1) of the first (30.1) and the second portion disc (30.2) is substantially flat, and in that the top (34; 134) of the bump(s) (32; 132) rises above the substantially flat surface {26,1} by a height (H1; HZ) which is between 0.5 and 5 mm, preferably between 1 and 3 mm. 7, blade (9; 109) according to the preceding claim, characterized in that the height (H1} of the top (34; 134) of the first boss (32} is between 0.1 and 0.3 times the thickness maximum (6) of the blade (113 or between 3 times said maximum thickness (8), andor the height (H2) or top (134) of the second boss (132) is between 0.1 and 0.3 times the thickness maximum (8) of the blade (11) or between 1 to 3 times said maximum thickness {e). 8. Blade (9; 109) according to claim 6 or 7, characterized in that the height {H1; H2} of the vertex (34; 134} of Ia or of the bumps (32; 132) is between 1% and 10% of the chord (G}. 3. Blade (©; 109) according to one of the preceding claims, characterized in that the bump(s) (32; 132) are at a distance from the peripheral edge (26,2). 10. Blade (9; 109) according to one of the preceding claims, characterized in that the first boss (32) has a main orientation (32.1) which forms an angle of between 30" and 60° with the chord line (LC) of Taube {9; 108), 11, Dawn (9; 109) according to one of claims 4 to 10, characterized in that the second bump (132) has a truncated cardioid shape. 12. Aircraft turbomachine (4) comprising a compressor (2), said compressor (2) comprising a guiding surface (18.1, 30.1) of a substantially axisymmetric air flow (F1), the turbomachine (4) being characterized in that it comprises an annular row of blades (9; 109) according to one of claims 1 to 11, the platforms (26) of the blades (9; 109) being received in housings (31) of the casing (18, 30) such that the air guiding surfaces (26.1) of the platforms (25) are substantially flush with the air flow guiding surface (18.1, 30.1} (F1} of the casing (18, 30).