Turbomachine component

Abstract

Turbomachine component (3) having an aerodynamic surface, the aerodynamic surface comprising a plurality of scales (70) configured to reduce gas flow separation at the surface of the component, each scale (7) comprising: - a foot (71) fixed to the aerodynamic surface; and - an aerodynamic body (72) mounted on the foot (71) at a distance from the aerodynamic surface, forming a gap between the aerodynamic surface and the aerodynamic body (72), so as to reduce friction at the aerodynamic surface of the turbomachine component (3). Figure for the abbreviation: Fig. 2

Description

Title of the invention: Turbomachine component technical field

[0001] This disclosure relates to the general field of turbomachinery, and more particularly to distributor or exhaust housing blades. STATE OF THE ART

[0002] A turbomachine is a device which generates thrust using a flow of gas circulating in a flow channel of the turbomachine, between rotor blades movable about an axis of rotation, and fixed stator blades, for example distributor blades or exhaust casing blades.

[0003] Depending on the engine speed, the gas flow enters the turbomachine at an inlet angle relative to the turbomachine's axis of rotation. This inlet angle can, however, fluctuate considerably depending on flight conditions, the turbomachine configuration, and its location within the turbomachine. For example, the inlet angle of the gas flow can vary by several tens of degrees, reaching approximately forty degrees, between take-off and cruise speeds in the exhaust casing of turbomachines with a high-speed turbine. One consequence of this wide variability in the angles of incidence is that significant gas flow separation can be observed in various areas, particularly at the turbine blades, which reduces aerodynamic performance.

[0004] Solutions have been developed to limit flow separation without reducing turbomachine performance. For example, document WO2019239064A1 proposed mounting the distributor blades on a platform with orifices to reinject the leakage flow into the flow stream. However, such platforms are bulky and complex to design. Moreover, they only affect airflow separation in the vicinity of the platform. GENERAL DESCRIPTION

[0005] One purpose of this disclosure is to propose a device to reduce, or even avoid, gas flow separation on a turbomachine component, regardless of the angle of incidence between the gas flow and the component.

[0006] This objective is achieved by a turbomachine component having an aerodynamic surface, the aerodynamic surface comprising a plurality of scales configured to reduce gas flow separation at the surface of the component, each scale comprising: - a foot fixed on the aerodynamic surface; and - an aerodynamic body mounted on the foot at a distance from the aerodynamic surface forming a space between the aerodynamic surface and the aerodynamic body, so as to reduce friction at the level of the aerodynamic surface of the turbomachine component.

[0007] The presence of multiple scales, each comprising an aerodynamic body, on the aerodynamic surface of the turbomachine component prevents the gas flow arriving at the aerodynamic surface from separating. Indeed, the aerodynamic body of the scales forces the gas flow arriving at the aerodynamic surface to remain close to it. Furthermore, the characteristic shape of the aerodynamic body of the scales allows the fluid to flow laminarly, that is, in the direction of flow, over the external surface of the aerodynamic body. This results in reduced friction at the aerodynamic surface of the turbomachine component.

[0008] These scales have been named “nicopass riblets”, in reference to the names of the inventors.

[0009] The invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations:

[0010] - the plurality of scales are arranged over all or part of the aerodynamic surface, so as to reduce turbulence in the gas flow at the aerodynamic surface;

[0011] - the aerodynamic surface comprises a leading edge, a foot and a top, a height of the component corresponding to a distance between the base and the top, and in which the plurality of scales are arranged on the leading edge, preferably over the entire height of the component;

[0012] - the aerodynamic surface further has a trailing edge which is devoid of scales;

[0013] - for all or part of the scales, the aerodynamic body includes an edge leading edge, trailing edge, and a chord connecting the leading edge to the trailing edge, the chord being taken in a plane cutting the foot, the chord forming an angle with a tangent to the aerodynamic surface at the level of its intersection with the plane between 10° and 20°;

[0014] - the plurality of scales overlap so that the aerodynamic body of a The first scale partially covers the aerodynamic body of a second scale adjacent to the first scale;

[0015] - the aerodynamic body of all or part of the scales has a leading edge, a trailing edge and a top surface shaped so that a curve of length minimal belonging to the upper surface connecting the leading edge to the trailing edge has an inflection point;

[0016] - the aerodynamic body of all or part of the scales comprises a plane of symmetry;

[0017] - the aerodynamic body of all or part of the scales comprises a first lateral portion and a second lateral portion extending on either side of the foot, the first lateral portion and the second lateral portion extending from a central ridge presenting a concave upper surface;

[0018] - the concave upper surface of the first lateral portion and the upper surface concave of the second lateral portion present two successive concave shapes from the central edge;

[0019] - the central edge successively presents a convex shape and a concave shape;

[0020] - for all or part of the scales, the aerodynamic body includes a trailing edge, presenting a concave shape on either side of the central edge;

[0021] - the aerodynamic body of all or part of the scales comprises a surface lower presenting a convex shape;

[0022] - for all or part of the scales, the aerodynamic body includes an edge leading edge, trailing edge, and a chord connecting the leading edge to the trailing edge, the chord being taken in a plane cutting the foot, a curve corresponding to an intersection between a plane including the chord and the leading edge and / or the trailing edge includes a cusp point;

[0023] - all or part of the scales have a placoid scale shape.

[0024] According to another aspect, a turbomachine assembly is proposed comprising a housing and a component as described above, the component being a stator vane, for example a vane from an exhaust housing or a vane from a distributor.

[0025] According to a second aspect, a turbomachine is proposed comprising an exhaust housing formed by the assembly described above.

[0026] According to a third aspect, an aircraft is proposed comprising at least one turbomachine conforming to the second aspect mounted on the aircraft via a pylon. DESCRIPTION OF THE FIGURES

[0027] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings.

[0028] Fig. 1 represents a simplified diagram of a turbomachine cross-section in a plane containing the axis of rotation.

[0029] Fig. 2 is a perspective view of a turbomachine component according to a first embodiment.

[0030] Fig. 3 schematically illustrates a section of a turbomachine component according to a second embodiment.

[0031] Fig. 4 is a perspective view of an example of the realization of a scale.

[0032] Fig. 5 is a front view of the example of an embodiment of a scale of Fig. 4.

[0033] Fig. 6 is a side view of the example of the realization of a scale of Fig. 4.

[0034] Figure 7 is a top view of an example embodiment of an assembly of several scales conforming to a method of embodiment.

[0035] Fig. 8 is a perspective view of a turbomachine assembly according to a third embodiment.

[0036] Fig. 9 is a schematic top view of an aircraft.

[0037] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0038] In this application, upstream and downstream are defined with respect to the normal flow direction of the gas through the turbomachine. Furthermore, the X-axis of the turbomachine is the axis of rotation of its rotor parts. The axial direction corresponds to the direction of the X-axis, and a radial direction is a direction perpendicular to and passing through this axis. The circumferential (or lateral) direction corresponds to a direction perpendicular to and not passing through the X-axis. Unless otherwise specified, internal (respectively, inside) and external (respectively, outside) are used with reference to a radial direction, such that the inner part or face of an element is closer to the X-axis than the outer part or face of the same element. A surface forming a hollow is generally described as "concave," and a surface forming a raised area, such as a bump, as "convex."

[0039] Fig. 1 schematically represents a section of a turbomachine 10 in a plane containing the X-axis. This disclosure extends more generally to different turbojet architectures, including unfaired turbojets, and is not limited to a faired turbojet with a turbofan engine, as described below.

[0040] The turbomachine 10 comprises, from upstream to downstream in the direction of the gas flow, a blower 11, a compressor section 16, a combustion chamber 14, a turbine section 15 and an exhaust casing.

[0041] The turbine section 15 comprises a succession of stages, each including a fixed stator part behind which a movable rotor part can be driven in rotation around the longitudinal axis X.

[0042] The turbomachine 10 includes an engine casing 21. The engine casing 21 forms an enclosure surrounding the compressor section 16, the combustion chamber 14, the turbine section 15 and the exhaust casing, and delimiting a primary channel 13 allowing the flow of a primary gas stream A.

[0043] The stator and rotor sections are formed of blades extending radially from an inner ferrule 18 into the primary stream 13. The blades of the stator sections are fixed at their outer end to the engine casing 21. When the turbomachine 10 is operating, the gas flow circulating in the primary stream 13 is deflected by the rotating rotor sections and straightened by the stator sections. The stator sections of the turbine section 15 are called distributor blades, and the stator sections of the compressor section 16 are called rectifier blades.

[0044] In the embodiment shown, the turbojet also includes an intermediate casing 20 for transmitting forces to a structure on which the turbojet will be fixed, such as a pylon.

[0045] The exhaust casing 17 is connected to the engine casing 21 downstream of the turbine section 15.

[0046] The exhaust housing 17 comprises an outer casing, an inner casing, and a plurality of exhaust housing vanes (or arms). The vanes are profiled and are distributed around the X-axis, extending radially from the inner casing to the outer casing.

[0047] This disclosure applies to any turbomachine component having an aerodynamic surface, that is, a surface along which the gas flow in the primary 13 or secondary 12 can circulate. For example, the turbomachine component may be a blade fixed relative to the casings 20, 21, in particular a distributor blade of the stator parts of the turbine section 15 (TRF, acronym for "Turbine Rear Frame"), a blade of the exhaust casing 17, or a straightener of the fan section (OGV, acronym for "Outlet Guide Vane"). In what follows, the invention will be described in the case where the component comprises a stator blade. However, as stated above, this is not limiting; the component may also comprise a casing or, more generally, be any turbomachine component having an aerodynamic surface.

[0048] The blade 3 extends along a radial axis Y between a root and a tip. The blade 3 comprises, in a manner known per se, a leading edge 31, a trailing edge 32, an intrados wall 34, and an extrados wall 33. The leading edge 31 is configured to extend opposite the flow of gases entering the turbomachine 10. It corresponds to the forward part of an airfoil that faces the flow of The gas flow divides the airflow into an intrados (lower surface) and an extrados (upper surface) flow. The trailing edge 32 corresponds to the rear part of the airfoil, where the intrados and extrados flows meet. The blade 3 also has a height, which corresponds to the distance, measured at the leading edge 31 along the radial axis Y, between the root and the tip of the stator blade, and a chord, which corresponds to the segment passing through a point at the intersection of the leading edge 31 and the root and a point at the intersection of the trailing edge 32 and the root. The root of the stator blade is fixed to an inner shell 4, and the tip of the blade 3 is fixed to an outer shell 5.

[0049] For example, the inner casing 4 can correspond to the inner shell 18 in a turbine 15 or alternatively to the inner casing of the exhaust housing 17. The outer casing 5 can correspond to the engine housing 21 or to the exhaust housing 17. When the turbomachine is in operation, a gas flow is intended to flow in the channel 13 delimited between the inner casing 4 and the outer casing 5. In operation, the gas flow can enter the turbomachine 10 at an inlet angle with respect to the longitudinal axis X, and flow in the channel 13. The gas flow reaches the turbomachine component 3 at an angle of incidence α with the chord. The angle of incidence a can vary greatly depending on the engine speed of the turbomachine 10. For large angles of incidence, a separation of the gas flow can be observed at the level of the intrados 34 or the extrados 34.

[0050] In order to reduce gas flow separation at the surface of the turbine blade 3 of the turbomachine 10, the aerodynamic surface comprises a plurality of scales 70, each scale 7 comprising:

[0051] - a foot 71 fixed to the aerodynamic surface; and

[0052] - an aerodynamic body 72 mounted on the foot at a distance from the surface aerodynamic forming a space between the aerodynamic surface and the aerodynamic body 72, so as to reduce friction at the level of the aerodynamic surface of the turbomachine component.

[0053] The space formed between the aerodynamic surface and the aerodynamic body 72 allows for the circulation of gas flow between the aerodynamic surface and the aerodynamic body 72. However, the foot 71 forming this space offers a structural advantage by allowing for the arrangement of several overlapping scales 7. Indeed, the gas flow is intended to flow primarily over the aerodynamic body 72 of the plurality of scales, adhering to the upper surface of the aerodynamic body. To this end, the aerodynamic body has an aerodynamic profile that allows for a more laminar flow of gas at the upper surface. This helps to reduce friction at the aerodynamic surface of the turbomachine component.

[0054] The scales 70 are arranged over all or part of the aerodynamic surface. This reduces turbulence in the gas flow at the aerodynamic surface. For example, the plurality of scales 70 can be arranged over a majority of the aerodynamic surface.

[0055] In one embodiment, the scales 70 are arranged in areas of the aerodynamic surface where the airflow is likely to separate. The areas of interest can be determined by computational fluid dynamics (CFD) simulations or experimental observations.

[0056] For example, the scales 70 are arranged on the leading edge 31 of the blade 3, preferably over the entire height of the blade 3. This prevents flow separation at the leading edge 31, the flow being redirected by the scales 70 to circulate between the aerodynamic surface and the aerodynamic body 72 of each scale 7.

[0057] In order to reduce tailstock losses due to separation at the trailing edge 32, which lead to a decrease in the efficiency of the turbomachine 10, it is preferable for the trailing edge 32 to be thin. Thus, the blade 3 can have a trailing edge 32 without scales. This reduces the wake of component 3 and therefore reduces tailstock drag, i.e., aerodynamic losses, at the trailing edge 32. Such an embodiment is shown illustratively in Figures 2 and 3. The scales can then be arranged on a portion of the aerodynamic surface representing an area between 80% and 95% of the total aerodynamic surface area, with the trailing edge 32 then being included within the aerodynamic surface without scales 7.

[0058] Considering a projection of the aerodynamic surface onto the chord, the portion comprising the plurality of scales 70 preferably covers at least 80% of the chord length from the leading edge. Even more preferably, the portion comprising scales 70 covers between 80% and 95% of the chord length. The remaining portion of the aerodynamic surface, not covered by the plurality of scales 70, comprises the trailing edge 32.

[0059] The foot 71 of the scales is fixed to the aerodynamic surface of the blade 3 at a fixing zone. The foot 71 extends along a principal direction defining a principal axis Z, which may be substantially perpendicular to a tangent to the aerodynamic surface at the fixing zone.

[0060] The foot 71 and the aerodynamic body 72 are monolithic, so that they are formed integrally and in one piece. The scales can further be monolithic with the aerodynamic surface of the blade 3.

[0061] Preferably, the foot 71 has a height of less than 8 mm to guide the gas flow along the aerodynamic surface, where the height is measured from the attachment area to the interface between the foot 71 and the aerodynamic body 72, along the Z-axis. Preferably, the height of the foot 71 is less than or equal to 5 mm. Each scale 7 may have a height of less than 1 cm, preferably less than 5 mm, where the height of the scale 7 is measured between the attachment area and a vertex of the scale 7 along the Z-axis. Preferably, the height of the scale 7 is limited so as not to increase the size of the blade 3 in the channel 13, thereby not reducing the cross-sectional area for the gas flow and thus not impairing the performance of the turbomachine 10.

[0062] Advantageously, the foot 71 forms a profiled peduncle comprising a section in a plane orthogonal to the main direction Z whose area decreases between a basal plate or base 73, adjacent to the attachment zone, and the aerodynamic body 72. This makes it possible to delimit a passage for the gas flow and to avoid separation.

[0063] The aerodynamic body 72 forms a median keel comprising two fins extending laterally on either side of the foot 71 so as to cover the foot 71. Alternatively, the aerodynamic body 72 may comprise only one fin extending laterally from the top of the foot. The scale then has a substantially angled shape.

[0064] The aerodynamic body 72 comprises a leading edge 74, a trailing edge 75, and a chord connecting the leading edge to the trailing edge, being taken in a plane intersecting the foot 71. In [Fig. 4], the chord is the segment connecting the most upstream point of the leading edge 74 and the most downstream point of the trailing edge 75, in the direction of gas flow represented by arrow A. The foot 71 can be centered with respect to the aerodynamic body 72 and extend to a substantially equal distance from its leading edge 74 and its trailing edge 75.

[0065] The aerodynamic body 72 is inclined with respect to a plane tangent to the aerodynamic surface, taken at the level of the attachment zone. The aerodynamic body 72 is therefore not parallel to the aerodynamic surface, its trailing edge 75 being closer to the aerodynamic surface than its leading edge 74.

[0066] For example, the chord forms an angle [3 with the tangent plane, and therefore more generally a tangent, to the aerodynamic surface at the level of its intersection with foot 71 which is between 10° and 20°.

[0067] The inclination of the scales 7 allows them to be placed with overlap, so that the aerodynamic body 72a of a first scale 7a partially covers the aerodynamic body 72b of a second scale 7b adjacent to the first scale 7a. This configuration effectively improves the flow of the gas over the bodies aerodynamics 72 of the scales 7 and allows increasing the density of scales on the aerodynamic surface. For example, in the embodiment shown in [Fig. 7], the aerodynamic body 72a partially covers a lateral portion of the aerodynamic body 72b of the adjacent scale 7b and a portion of the leading edge of the aerodynamic body 72c of the downstream scale 7c, in the direction of the gas flow.

[0068] In one embodiment, the scales 70 are arranged in a staggered pattern to further increase the density of scales 7 present on the aerodynamic surface. For example, the scales 70 can be arranged so that the downstream point of the trailing edge of an upstream scale 7a is aligned with the upstream point of the leading edge of the immediately downstream scale 7c.

[0069] An overlap of the scales 7 improves the coverage of the aerodynamic surface by the plurality of scales 70 and allows a more laminar flow of gas near the upper surface of the aerodynamic bodies 72 of the scales 7. This helps to reduce the separation phenomenon and contributes to improving the aerodynamic efficiency of the turbomachine 10.

[0070] The wingspan of the scale 7 is greater than the width at the top of the foot 71. In other words, the distance between the lateral ends of the two fins of the aerodynamic body 72 is greater than the width of the base 73, so that the scale 7 covers the base 73 and protrudes on either side of it. The foot 71 may have a cross-sectional area that decreases from the aerodynamic surface towards the aerodynamic body 72: the wingspan of the scale 7 may then be substantially equal to the width of the base of the foot 71.

[0071] The aerodynamic body 72 may include a central edge from which the two fins extend. The edge may be sharp or convex. The central edge may correspond to an axis of symmetry of the median hull.

[0072] The aerodynamic body 72 of all or part of the scales 7 may comprise a first lateral portion and a second lateral portion extending on either side of the foot 71, the first lateral portion and the second lateral portion extending from the central edge with a concave upper surface. In other words, each lateral portion forms a groove allowing for a more laminar flow of the gas stream.

[0073] For example, the aerodynamic body 72 of the scale 7 has a top surface which has at the level of each fin a hollow (concave) shape in the lateral direction, i.e. forming a hollow from the central edge towards the lateral end of the fin whose bottom is oriented towards the aerodynamic surface.

[0074] The concave upper surface of the first lateral portion and the concave upper surface of the second lateral portion may have two concave shapes successive concave shapes originate from the central edge. Typically, the two successive concave shapes are separated by a crown. The free (lateral) end of each fin can be thinned along the Z-axis to form a lateral keel. In one embodiment, the thinning begins at a break in slope, corresponding to the crown, where the upper surface of the fin is inclined towards the aerodynamic surface. This reduces the impact of the aerodynamic body 72 on the gas flow circulating above the upper surface. In one embodiment, the upper surface of the aerodynamic body 72 of the scale 7 is shaped such that a curve of minimum length belonging to the upper surface, connecting the leading edge 74 to the trailing edge 75, has an inflection point F.Furthermore, the portion of the upper surface located between the leading edge 74 and the inflection point F is convex, and the portion of the upper surface located between the inflection point F and the trailing edge 75 is concave. This creates a low-turbulence phenomenon downstream of the upper surface of the aerodynamic body 72 and results in laminar flow over the upper surface. This helps to reduce aerodynamic losses.

[0075] For example, the central edge successively has a convex shape and a concave shape, typically in the direction of flow of the gas flow.

[0076] Preferably, the aerodynamic body 72 of all or part of the scales 7 comprises a lower surface having a convex shape. Typically, the aerodynamic body 72 of the scale 7 has a lower surface that has at least one convex shape in the lateral direction. For example, each fin extending on either side of the foot has a hollow lower wall, so as to increase the flow space of the gas flow between the aerodynamic body 72 and the aerodynamic surface.

[0077] In one embodiment, a curve corresponding to an intersection between a plane comprising the chord and the leading edge 74 and / or the trailing edge 75 includes a cusp point. This means that the curve includes a singularity at the point belonging to the leading edge 74 and / or the trailing edge 75. The curve has two curve segments joining at the cusp point, the two curve segments having the same tangent in the same direction at this point.

[0078] The presence of an upstream point on the leading edge 74, forming a cusp point, advantageously directs the gas flow at the upper surface, preventing it from separating at the aerodynamic surface of the component. The gas flow in the channel above the scale 7 is more laminar. This helps to reduce aerodynamic losses.

[0079] The presence of a downstream point on the trailing edge 75 forming a cusp point advantageously reduces base losses at the level of each aerodynamic body 72, which could negatively impact the aerodynamic efficiency of the turbomachine 10. For example, in the illustrated embodiment, the trailing edge 75 has a concave shape on each side of the central edge. The trailing edge 75 has a median point, at the level of the most downstream point of the aerodynamic body 72, and two lateral points.

[0080] Each scale 7, or more generally the aerodynamic body 72 of all or part of the scales, may include a plane of symmetry containing the principal axis Z. The plane of symmetry may correspond to the plane intersecting the foot 71, for example, be coplanar with the plane of [Fig. 6]. For example, the scale 7 may include a first fin symmetrical to a second fin with respect to this plane of symmetry.

[0081] The aerodynamic body 72 may have a chord length of less than 2 cm, preferably less than 1 cm. The aerodynamic body 72 has a width corresponding to the maximum distance between two points of the aerodynamic body 72, along a direction perpendicular to the chord. Preferably, the aerodynamic body 72 has a width of less than 2 cm, preferably less than 16 mm.

[0082] In one embodiment, the scale 7 has the shape of a placoid scale. More generally, all or part of the scales 7 may have a placoid scale shape. Thus, the aerodynamic body 72 may have a shape inspired by nature, for example, inspired by fish or shark scales. The particular shape of a placoid scale can reduce turbulence at the aerodynamic surface, for example, by guiding the gas flow along the two convex lateral fins extending on either side of the central edge. This can reduce drag and aerodynamic losses and reduce the noise emitted by the turbomachine 10. In the placoid scale shape shown illustratively in [Fig. 4], the leading edge 74 is concave on either side of the cusp. Alternatively, the leading edge may be convex.

[0083] All the scales 7 of the plurality of scales 70 may be identical. Alternatively, the shape and / or size of the scales 7 may vary according to an area of ​​the aerodynamic surface. For example, the inclination of the aerodynamic body 72 relative to the foot 71 or a dimension of the aerodynamic body 72 and / or the foot 71 may vary on the aerodynamic surface of the component 3. A portion of the plurality of scales 70 may be aligned along a direction, i.e., arranged along several parallel straight lines, preferably along the direction of gas flow, or an orthogonal direction. For example, the respective chords of the scales 70 may all be oriented in the same direction.

[0084] Preferably, the scales 70 are not in contact with the adjacent scales.

[0085] Dawn 3 and scales 70 can, for example, be produced by manufacturing Additive manufacturing, for example by powder bed fusion. Such a manufacturing method is particularly advantageous, as it allows a defect tolerance of less than 1 mm, preferably less than 0.5 mm.

[0086] Thus, the blade 3 can be manufactured in a single operation by additive manufacturing, that is to say, the plurality of scales 70 are not attached and fixed to the aerodynamic surface after the fact, but formed integrally and in one piece with the aerodynamic surface of the blade. Such a process advantageously simplifies the manufacture of the blade 3 and ensures good mechanical strength of the blade 3 and the scales 70.

[0087] The scales 70 can be made of a material capable of withstanding the high temperatures prevailing in the flow channel 13 and high pressures without deforming. Likewise, the material used is sufficiently rigid to prevent vibrations of the scales that would alter the gas flow in the channel 13. For example, the plurality of scales 70 can be made of a metal alloy, preferably the same metal alloy as the turbomachine component 3. For example, a nickel-based superalloy, such as Inconel®, can be used. Such metal alloys are resistant to oxidation and corrosion and can withstand high mechanical and thermal loads.

[0088] A turbomachine assembly according to this disclosure may include a housing and a blade fixed relative to the housing, for example an exhaust housing blade or a distributor blade.

[0089] The turbomachine assembly may include two stator blades 3a,3b, extending between the inner shell 4 and the outer shell 5 of the casing.

[0090] The outer envelope 5 may include an aerodynamic surface 51 with also a plurality of scales 70. This advantageously prevents the gas flow from separating at the tops of the stator blades 3a,3b, and near the wall of the casing 21,17.

[0091] Alternatively or complementarily, the inner envelope 4 may include an aerodynamic surface 41 comprising a plurality of scales 70. This advantageously prevents the gas flow from separating at the base of the stator blades 3a,3b, and near the wall of the inner shell.

[0092] The present description finds a particularly advantageous application in the exhaust casing stator blades 17, since such components are subjected to varying angles of incidence that generate gas flow separation. Furthermore, the exhaust casing can be easily disassembled, allowing for cleaning or maintenance. Finally, the exhaust casing stator blades 17 are subjected to moderate temperatures compared to the rest of the turbomachine 10, which limits the risk of deformation of the plurality of scales 70.

[0093] The turbomachine assembly described above can be advantageously integrated into a turbomachine 10. Thanks to the plurality of scales 70 allowing the reduction of gas flow separation in the vein 13, the efficiency of the turbomachine 10 can be improved.

[0094] This disclosure also relates to an aircraft 100, comprising at least one propulsion unit 1 including a turbomachine 10 with a component comprising a plurality of scales.

[0095] The turbomachine 10 is mounted on the aircraft 100 by means of a pylon.

Claims

Demands

1. Turbomachine component (3) having an aerodynamic surface, the aerodynamic surface comprising a plurality of scales (70) configured to reduce gas flow separation on the surface of the component, each scale (7) comprising: - a foot (71) fixed on the aerodynamic surface; and - an aerodynamic body (72) mounted on the foot (71) at a distance from the aerodynamic surface forming a space between the aerodynamic surface and the aerodynamic body (72), so as to reduce friction at the aerodynamic surface of the turbomachine component (3).

2. Turbomachine component according to claim 1, wherein the plurality of scales (70) are arranged on all or part of the aerodynamic surface, so as to reduce gas flow turbulence at the level of the aerodynamic surface.

3. Turbomachine component according to claim 2, wherein the aerodynamic surface comprises a leading edge, a foot and a top, a height of the component corresponding to a distance between the foot and the top, and wherein the plurality of scales (70) are arranged on the leading edge, preferably over the entire height of the component.

4. Turbomachine component according to claim 3, wherein the aerodynamic surface further has a trailing edge which is devoid of scales.

5. Turbomachine component according to any one of claims 1 to 4, wherein, for all or part of the scales (7), the aerodynamic body (72) comprises a leading edge (74), a trailing edge (75), and a chord connecting the leading edge (74) to the trailing edge (75), the chord being taken in a plane intersecting the foot (71), the chord forming an angle with a tangent to the aerodynamic surface at the level of its intersection with the plane between 10° and 20°.

6. A turbomachine component according to any one of claims 1 to 5, wherein the plurality of scales (70) overlap such that the aerodynamic body (72a) of a first scale (7a) partially covers the aerodynamic body (72b) of a second scale adjacent (7b) to the first scale (7a).

7. Turbomachine component according to any one of claims 1 to 6, wherein the aerodynamic body (72) of all or part of the scales (7) has a leading edge (74), a trailing edge (75) and a top surface shaped such that a curve of minimum length belonging to the top surface connecting the leading edge (74) to the trailing edge (75) has an inflection point.

8. Turbomachine component according to any one of claims 1 to 7, wherein the aerodynamic body (72) of all or part of the scales (7) comprises a plane of symmetry.

9. Turbomachine component according to any one of claims 1 to 8, wherein the aerodynamic body (72) of all or part of the scales (7) comprises a first lateral portion and a second lateral portion extending on either side of the foot (71), the first lateral portion and the second lateral portion extending from a central edge having a concave upper surface.

10. Turbomachine component according to claim 9, wherein the concave upper surface of the first lateral portion and the concave upper surface of the second lateral portion have two successive concave shapes from the central edge.

11. Turbomachine component according to any one of claims 9 and 10, wherein the central edge successively has a convex shape and a concave shape.

12. Turbomachine component according to any one of claims 9 to 11, wherein, for all or part of the scales (7), the aerodynamic body (72) comprises a trailing edge having a hollow shape on either side of the central edge.

13. Turbomachine component according to any one of claims 1 to 12, wherein the aerodynamic body (72) of all or part of the scales (7) comprises a lower surface having a convex shape.

14. Turbomachine component according to any one of claims 1 to 13, wherein, for all or part of the scales (7), the aerodynamic body (72) comprises a leading edge (74), a trailing edge (75), and a chord connecting the leading edge (74) at trailing edge (75), the rope being taken in a plane cutting the foot (71), a curve corresponding to an intersection between a plane including the rope and the leading edge (74) and / or the trailing edge (75) including a cusp point.

15. Turbomachine component according to any one of claims 1 to 14, wherein all or part of the scales (7) have a placoid scale shape.

16. Turbomachine assembly comprising a housing and a component according to any one of claims 1 to 15, the component being a stator blade (3), for example a blade of an exhaust housing or a blade of a distributor.

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