Wall equipped with a cooling orifice having a single-lobe diffusion portion

Abstract

The invention relates to a turbomachine component such as a blade, comprising a wall having at least one cooling orifice and a metering portion and a diffusion portion (33). According to the invention, the diffusion portion (33) comprises a single lobe (38) delimited by straight edges (40, 41) along their entire extent. Figure for the abstract: Fig. 4

Description

Title of the invention: Wall provided with a cooling orifice having a single-lobe diffusion portion technical field

[0001] The invention relates to the field of aircraft turbomachinery and to the field of air-film cooling of components such as turbine blades. Prior art

[0002] A conventional turbomachine turbine comprises at least one distributor and at least one moving wheel, each having blades exposed to hot combustion gases.

[0003] In order to preserve the mechanical integrity of the blades, it is known to introduce fresh air into them and to provide them with cooling orifices configured to direct some of this fresh air onto their external surface so as to form a thermal protection film.

[0004] A conventional blade cooling orifice includes a metering portion, also called a "calibrating portion", generally cylindrical, which allows adjustment of the quantity of air passing through this orifice and a flared diffusion portion improving the distribution of the cooling air on the external surface of the blade.

[0005] The flow of fresh air exiting a conventional cooling orifice is exposed to counter-rotating vortices that form at the outlet section of this orifice, resulting in separation of the fresh air flow and the ingestion of hot gases into the cooling orifice. This leads to a reduction in cooling efficiency.

[0006] In the prior art, the diffusion portion is either delimited by a smooth surface devoid of geometric discontinuities, or it includes lobes formed in hollows in the wall of the blade.

[0007] In a conventional diffusion portion comprising a central lobe and two lateral lobes, the lateral lobes make it possible to protect the flow of the central lobe from counter-rotating vortices, which makes it possible to improve the efficiency of the cooling.

[0008] The production of lobes increases the cost and manufacturing time of the blades, a fortiori when they have a complex geometry. Description of the invention

[0009] One object of the invention is to simplify the manufacture of such a cooling orifice while preserving satisfactory cooling efficiency during its implementation.

[0010] To this end, the invention relates to a component for a turbomachine, comprising a wall having a first surface and a second surface opposite to the first surface, the wall comprising a cooling orifice configured to convey a cooling fluid from the first to the second surface through the wall, the cooling orifice comprising a metering portion opening onto the first surface and a diffusion portion opening onto the second surface, the diffusion portion being delimited by a flared surface which defines a principal flow direction within this diffusion portion, the flared surface comprising two edges delimiting a lobe which extends along the principal flow direction between an upstream end formed by a first end of the edges and a downstream end formed by a second end of the edges.

[0011] According to the invention, the lobe is unique within the diffusion portion and the flared surface is flat on both sides of the lobe, the edges being straight over their entire extent.

[0012] Conventionally in the field of the invention, a lobe is a part of the diffusion portion formed in a hollow in the wall and defining a duct or groove which has a relatively small cross-section compared to the total cross-section of the diffusion portion.

[0013] The lobe of the invention makes it possible to channel a fraction of the cooling fluid and to move it away from the area of ​​influence of the counter-rotating vortices forming at the outlet of the diffusion portion.

[0014] This makes it possible to reduce the ingestion of hot gases into the cooling orifice, in particular into the lobe, and to reduce or avoid the phenomenon of detachment of the fluid channeled by the lobe.

[0015] The presence of a single lobe in the diffusion portion promotes the channeling of this fluid fraction.

[0016] The invention thus makes it possible to improve the efficiency of the cooling.

[0017] Moreover, the uniqueness of the lobe and its delimitation by straight edges over its entire extent, that is to say by completely straight edges devoid of curved parts, simplifies the manufacture of the component.

[0018] Preferably, the second end of each of the edges forms a boundary point between the second surface and the flared surface.

[0019] In other words, it is preferred that the lobe extends to the exit of the diffusion portion.

[0020] This makes it possible to further simplify the machining of the lobe while improving cooling efficiency.

[0021] In one embodiment, the lobe has a section increasing along the main flow direction, in a direction going from an inlet of the diffusion portion to an outlet of the diffusion portion.

[0022] For this purpose, the edges may be oblique to each other and / or the depth of the lobe may be increasing along the main flow direction.

[0023] In one embodiment, the flared surface comprises two flat portions, each delimited by one of the respective edges so as to extend on either side of the lobe.

[0024] The flat portions are preferably oblique with respect to an axis of the dosing portion.

[0025] Such a geometry promotes the distancing of the channeled fluid by the lobe from the area of ​​influence of the counter-rotating vortices, which makes it possible to further improve the efficiency of the cooling.

[0026] In one embodiment, the lobe has a parabolic, semi-circular, triangular, or rectangular cross-section.

[0027] Preferably, the lobe has a maximum depth less than or equal to three times the diameter of the dosing portion, more preferably less than or equal to half the diameter of the dosing portion.

[0028] In one embodiment, the lobe has a median axis that is oblique to the main flow direction.

[0029] The invention also relates to a turbine for a turbomachine, comprising a wheel, a distributor and at least one component as defined above forming a blade of the wheel or of the distributor.

[0030] The invention also relates to a combustion chamber for a turbomachine, comprising at least one component as defined above forming a wall of the combustion chamber.

[0031] The invention also relates to a turbomachine for an aircraft such as an airplane or a helicopter, comprising such a turbine and / or such a combustion chamber.

[0032] According to another aspect, the invention relates to a method for manufacturing a component as defined above.

[0033] In one embodiment, the process includes an electro-erosion machining step of the diffusion portion.

[0034] In one embodiment, the process includes a laser treatment step of said third wall surface.

[0035] This helps to reduce manufacturing time and cost.

[0036] Other advantages and features of the invention will become apparent from the following detailed, non-limiting description. Brief description of the drawings

[0037] The detailed description that follows refers to the accompanying drawings in which:

[0038] [Fig-1] is a schematic longitudinal cross-sectional view of a propulsion assembly aircraft;

[0039] [Fig.2] is a schematic perspective view of a moving wheel blade of a turbine of the propulsion assembly of the [Fig.1];

[0040] [Fig.3] is a schematic cross-sectional view of a wall comprising a cooling orifice according to the invention;

[0041] [Fig.4] is a schematic perspective view of a surface delimiting a diffusion portion of a cooling orifice according to the invention;

[0042] [Fig.5] is a schematic view of an outlet section formed by the diffusion portion of [Fig.4], illustrating a flow of fresh air channeled by a lobe of the diffusion portion and counter-rotating fluid vortices forming at the outlet section;

[0043] [Fig.6] ,

[0044] [Fig.7] ,

[0045] [Fig.8] ,

[0046] [Fig.9] and

[0047] [Fig. 10] are schematic views of different geometries of a section of a lobe formed by a diffusion portion of a cooling orifice according to the invention, in a plane perpendicular to a main flow direction;

[0048] [Fig. 11],

[0049] [Fig. 12] ,

[0050] [Fig. 13] ,

[0051] [Fig. 14] ,

[0052] [Fig. 15] and

[0053] [Fig. 16] are schematic views of different geometries of a lobe formed by a diffusion portion of a cooling orifice according to the invention. Detailed description of embodiments

[0054] Fig. 1 shows an aircraft propulsion assembly 1 (not shown) comprising a turbomachine 2 and a nacelle 3 extending around a longitudinal central axis A1.

[0055] Subsequently, the terms "upstream" and "downstream" are defined relative to an SI direction of gas flow through the propulsion assembly 1 along the axis Al.

[0056] In the example of [Fig.1], the turbomachine 2 is a turbofan engine comprising, from upstream to downstream, a fan 4, a low-pressure compressor 5, a high-pressure compressor 6, a combustion chamber 7, a high-pressure turbine 8 and a low-pressure turbine 9. The compressors 5 and 6, the combustion chamber 7 and the turbines 8 and 9 form a gas generator.

[0057] During the operation of the turbojet 2, an airflow 10 enters the propulsion assembly 1 through an air inlet in the nacelle 3, passes through the fan 4 and then It is divided into a central primary flow 10A and a secondary flow 10B. The primary flow 10A flows in a primary gas circulation duct 1IA within the gas generator. The secondary flow 10B flows in a secondary duct 1IB surrounding the gas generator and radially bounded outwards by the nacelle 3.

[0058] In a manner known per se, the turbines 8 and 9 each comprise at least one distributor and at least one moving wheel each having blades, visible on [Fig.1], which extend into the primary conduit 11A.

[0059] Figure 2 shows a vane 20 for a rotating wheel equipping in this example the high-pressure turbine 8.

[0060] The blade 20 has a conventional general structure, including a blade 21, a foot 22 intended to cooperate with a housing for a disc (not shown) of the moving wheel and a platform 23 intended to radially delimit inwards the primary conduit 11 A.

[0061] In service, the blade 21 extends into the primary conduit 1 IA and is consequently exposed to hot gases from the combustion chamber 7 (see [Fig.1]).

[0062] In a manner known per se, the turbojet 2 includes a cooling circuit for conveying fresh air into an internal cavity 25 of the blade 20.

[0063] The blade 20 includes cooling ports 26 connecting an internal surface (not visible in [Fig.2]) of the blade 21 to an external surface 27 of the blade 21, the internal surface delimiting the internal cavity 25, the external surface 27 being exposed to the primary flow 10A.

[0064] The cooling orifices 26 allow some of the fresh air circulating in the internal cavity 25 of the blade 20 to be evacuated so as to form on the external surface 27 a film of fresh air protecting the blade 21 from the hot combustion gases 10A.

[0065] The invention relates to the geometry of such cooling orifices 26.

[0066] Figure 3 shows a portion of a wall 30 comprising a re-orifice cooling 26 according to the invention.

[0067] The wall 30 has a first surface 31 delimiting a first space 25 and a second surface 27, opposite with respect to the first surface 31, delimiting a second space 11 A.

[0068] The distance between the first surface 31 and the second surface 27 defines a wall thickness 30.

[0069] The cooling orifice 26 is configured to convey a cooling fluid circulating in the first space 25 to the second space 11A through the wall 30, i.e. from the first surface 31 to the second surface 27, so as to form a film of cooling fluid on the second surface 27.

[0070] In this example, the wall 30 of [Fig.3] forms the blade 21 of the blade 20 of [Fig.2] , so that said first surface 31 forms the internal surface of blade 21, said second surface forms the external surface 27 of blade 21, said first space corresponds to the internal cavity 25 of blade 20 and said second space corresponds to the primary duct 11A of turbojet 2.

[0071] By way of non-limitation, in undetailed embodiments, the wall 30 of [Fig.3] can form a moving wheel blade and / or distributor of the high-pressure turbine 8 and / or the low-pressure turbine 9 and / or a wall of the combustion chamber 7. The present description applies by analogy to these embodiments.

[0072] In addition, the wall 30 may include several cooling ports 26 as described below with reference to Figures 3 and following.

[0073] With reference to [Fig.3], the cooling orifice 26 includes a dosing portion 32, or calibrating portion, which opens onto the first surface 31 so as to form an inlet 35 of the cooling orifice 26 and a diffusion portion 33 which opens onto the second surface 27 so as to form an outlet 36 of the cooling orifice 26.

[0074] In this example, the dosing portion 32 has a cylindrical section of diameter XI and has a central axis A2 oblique to the first surface 31.

[0075] The dosing portion 32 allows the quantity of cooling air entering the cooling orifice 26 through the inlet 35, from the first space 25, to be dosed or calibrated.

[0076] The diffusion portion 33 extends the dosing portion 32 so that the airflow entering the cooling orifice 26 through the inlet 35 can exit through the outlet 36.

[0077] With reference to a flow direction S2 of the cooling airflow thus passing through the cooling orifice 26, the downstream end 37 of the dosing portion 32, i.e. the outlet of the dosing portion 32, also forms the upstream end of the diffusion portion 33, i.e. the inlet of the diffusion portion 33.

[0078] The diffusion portion 33 is flared so that the outlet section 36 has an area greater than the area of ​​the upstream end 37 of the diffusion portion 33 and consequently greater than the area of ​​the inlet section 35.

[0079] The diffusion portion 33 includes a unique lobe 38 for channeling a fraction of the cooling fluid passing through the cooling orifice 26.

[0080] The diffusion portion 33, including the lobe 38, is formed by removing material from the wall 30 so that the latter forms a third surface 34 which delimits the diffusion portion 33.

[0081] The diffusion portion 33 being delimited by the third surface 34, the latter is also called the “flared surface”.

[0082] In the example of [Fig.3], the flared surface 34 forms a hollow 39 defining a line which extends the dosing portion 32 parallel to the axis A2 of the dosing portion 32. The cooling orifice 26 thus forms a straight line from the inlet 35 to the outlet 36.

[0083] The flare of the diffusion portion 33 of [Fig.3] is therefore not symmetrical around the axis A2 of the dosing portion 32.

[0084] It follows that the diffusion portion 33 defines a main flow direction A3 within this diffusion portion 33 which forms a non-zero angle with the axis A2 of the dosing portion 32.

[0085] Fig. 4 illustrates the geometry of the flared surface 34 of the wall 30, i.e. the contours of the diffusion portion 33 of the cooling orifice 26 of Fig. 3.

[0086] With reference to figures 3 and 4, the flared surface 34 comprises two edges 40 and 41 extending along the direction A3 and which delimit the lobe 38 circumferentially around this direction A3.

[0087] More specifically, the edges 40 and 41 extend along the direction A3 between the inlet 37 of the diffusion portion 33 and the outlet 36 of the cooling orifice 26.

[0088] In this example, the lobe 38 extends over the entire length of the diffusion portion 33.

[0089] In other words, the lobe 38 has along the main flow direction A3 an upstream end delimited by a first end of the edges 40 and 41 which coincides with the inlet 37 of the diffusion portion 33 and a downstream end delimited by a second end of the edges 40 and 41 which coincides with the outlet section 36.

[0090] Thus, in this example, the second end of each of the edges 40 and 41 forms a point, respectively 45 and 46, delimiting one with respect to the other the second surface 27 and the flared surface 34 of the wall 30.

[0091] The edges 40 and 41 are straight along their entire length, which facilitates the machining of the lobe 38.

[0092] With reference to [Fig. 4], the flared surface 34 comprises two substantially flat portions 43 and 44, the flat portion 43 being delimited by the edge 40, the flat portion 44 being delimited by the edge 4L

[0093] The flat portions 43 and 44 thus extend on either side of the lobe 38.

[0094] This configuration makes it possible, in particular, to simplify the machining of the portion of diffusion 33 by machining in a first step the part of the diffusion portion 33 outside lobe 38 so as to form a surface place integrating the flat portions 43 and 44.

[0095] In a subsequent second step, the wall 30 is machined by removing material at the level of this flat surface so as to form the lobe 38.

[0096] In this example, the flat portions 43 and 44 are oblique to the axis A2 of the dosing portion 32 and extend opposite the hollow 39 formed by the flared surface 34 (see [Fig.3]).

[0097] Following the flow direction S2, the flat portions 43 and 44 move away from the axis A2 of the dosing portion 32.

[0098] In this example, lobe 38 presents a growing section along the main flow direction A3, in the flow direction S2.

[0099] With reference to figures 3 and 4, the lobe 38 has a median axis A4 oblique to the main flow direction A3.

[0100] In this example, the axes A2 and A4 as well as the direction A3 belong to a plane of symmetry of the diffusion portion 33 and the cooling orifice 26.

[0101] Figure 5 shows the outlet section 36 of the cooling orifice 26, a flow 50 of cooling air channeled through the lobe 38 and counter-rotating vortices 51 forming at the outlet section 36.

[0102] The lobe 38 allows the flow 50 which it channels to be moved away from the area of ​​influence of the counter-rotating vortices 51.

[0103] Preferably, the maximum width of the lobe 38, i.e. the maximum distance Y1 separating the edges 40 and 41 from each other, is less than half the maximum width Y2 of the outlet section 36, which in the example of [Fig.5] corresponds to the distance between the end of the planar portion 44 opposite the edge 41 and the end of the planar portion 43 opposite the edge 40.

[0104] Figures 6 to 10 show non-limiting examples of the section of lobe 38 in a plane normal to the main flow direction A3, in this case a parabolic section at [Fig.6], a semi-circular section at [Fig.7], a section composed of a semi-circular part and a rectangular part at [Fig.8], a triangular section at [Fig.9] and a rectangular section at [Fig.10].

[0105] In the examples of figures 6 to 8, the part of the flared surface 34 forming the lobe 38 is smooth, without discontinuity between the edges 40 and 41, unlike the cases of figures 9 and 10 in which this part of the flared surface 34 includes an edge 60, or respectively two edges 61 and 62, at the bottom of the lobe 38.

[0106] Preferably, the maximum depth Y3 of the lobe 38, i.e., the distance between the deepest point of the lobe 38 and the edges 40 and 41 along a direction normal to a plane passing through the edges 40 and 41, is less than or equal to three times the diameter XI of the dosing portion 32, more preferably less than or equal to half of this diameter XL

[0107] In all these examples, lobe 38 exhibits lateral symmetry and therefore has a plane of symmetry passing through the median axis A4 of lobe 38. Of course, lobe 38 may exhibit lateral asymmetry without going outside the scope of the invention.

[0108] In the example of figures 4 and 11, the edges 40 and 41 are oblique to each other so that the distance Y1 separating them from each other increases along the median axis A4 of the lobe 38, in the flow direction S2.

[0109] In other embodiments, the aforementioned distance Y1 decreases along the median axis A4 of the lobe 38 in the direction of flow S2 ([Fig. 12]) or remains constant along this axis A4 ([Fig. 13]).

[0110] Preferably, the maximum distance Y1 is less than or equal to 2.5 times the diameter XI of the dosing portion 32 (see figures 3, 5 and 11-13).

[0111] Regardless of the evolution of the distance Y1 along the median axis A4, the lobe 38 can have a median axis A4 that is laterally oblique to the main flow direction A3 in the diffusion portion 33, in the manner illustrated in [Fig.14],

[0112] In the embodiments described above, the lobe 38 extends over the entire length of the diffusion portion 33, that is to say from the inlet 37 of the diffusion portion 33 to the outlet 36 of the cooling orifice 26.

[0113] Alternatively, the lobe 38 may have an upstream end 70 located downstream of the inlet 37 of the diffusion portion 33, as illustrated in [Fig. 15], and / or a downstream end 71 located upstream of the outlet 36 of the cooling orifice 26, as illustrated in [Fig. 16].

[0114] The inventors estimated that a cooling orifice 26 comprising a diffusion portion 33 as illustrated in [Fig.4] provides a cooling efficiency gain of more than twenty percent compared to a conventional diffusion portion without a lobe, at equivalent blowing rates.

[0115] Of course, the edges 40, 41, 60, 61 and 62 which are shown sharp in the figures may have a small radius of curvature, so as to form a rounded or fillet, taking into account manufacturing constraints.

Claims

Demands

1.

2.

3.

4. Component (20) for a turbomachine (2), comprising a wall (30) having a first surface (31) and a second surface (27) opposite to the first surface (31), the wall (30) comprising a cooling orifice (26) configured to convey a cooling fluid from the first (31) to the second surface (27) through the wall (30), the cooling orifice (26) comprising a metering portion (32) opening onto the first surface (31) and a diffusion portion (33) opening onto the second surface (27), the diffusion portion (33) being delimited by a flared surface (34) which defines a principal flow direction (A3) within this diffusion portion (33), the flared surface (34) comprising two edges (40, 41) delimiting a lobe (38) which extends along the principal flow direction (A3) between an upstream end formed by a first end of the edges (40,41) and a downstream end formed by a second end of the edges (40, 41), characterized in that the lobe (38) is unique within the diffusion portion (33) and in that the flared surface (34) is flat on both sides of the lobe (38), the edges (40, 41) being straight over their entire extent, in that the principal flow direction (A3) within the diffusion portion (33) forms a non-zero angle with an axis (A2) of the dosing portion (32), and in that the flared surface (34) forms a recess (39) defining a line extending the dosing portion (32) parallel to the axis (A2), the cooling orifice (26) forming a straight line from an inlet (35) to an outlet (36) of the cooling orifice (26). Component (20) according to claim 1, wherein the second end of each of the edges (40, 41) forms a boundary point (45, 46) between the second surface (27) and the flared surface (34). Component (20) according to claim 1 or 2, wherein the lobe (38) has a section increasing along the main flow direction (A3), in a direction going from an inlet (37) of the diffusion portion (33) to an outlet (36) of the diffusion portion (33). Component (20) according to any one of claims 1 to 3, in which the flared surface (34) comprises two flat portions (43, 44) each delimited by one of the respective edges (40, 41) so as to extend on either side of the lobe (38).

5. Component (20) according to claim 4, wherein the planar portions (43, 44) are oblique with respect to the axis (A2) of the dosing portion (32).

6. Component (20) according to any one of claims 1 to 5, wherein the lobe (38) has a parabolic or semi-circular or triangular or rectangular cross-section.

7. Component (20) according to any one of claims 1 to 6, wherein the lobe (38) has a median axis (A4) oblique to the main flow direction (A3).

8. Turbine (8, 9) for turbomachine (2), comprising a wheel, a distributor and at least one component (20) according to any one of claims 1 to 7 forming a blade (20) of the wheel or of the distributor.

9. Combustion chamber (7) for turbomachine (2), comprising at least one component according to any one of claims 1 to 7 forming a wall of the combustion chamber.

10. Turbomachine (2) for an aircraft such as an airplane or a helicopter, comprising a turbine (8, 9) according to claim 8 and / or a combustion chamber (7) according to claim 9.

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