Cooling air injector for turbomachine turbine

Abstract

The invention relates to a cooling air injector (30) for a turbine, comprising injection channels (35) extending in pairs head-to-tail so as to simultaneously cool an upstream and a downstream turbine disc. Figure for the abstract: Fig. 7

Description

Title of the invention: Cooling air injector for turbomachine turbine technical field

[0001] The invention relates to the field of turbomachine turbines, in particular for an aircraft propulsion system.

[0002] The invention relates more specifically to the ventilation of such a turbine. Prior art

[0003] A conventional turbomachine, for example a twin-spool turbojet, includes a ventilation circuit enabling in particular the cooling of moving wheels of a high-pressure turbine of this turbomachine.

[0004] Documents FR 2 841 591 Al and FR 2 777 318 Al disclose examples of high-pressure turbines.

[0005] The ventilation circuit of a turbomachine is generally configured to draw air from a high-pressure compressor of the turbomachine and to convey the air thus drawn into the turbine so as to supply one or more injectors extending into one or more cavities delimited by discs of the moving wheels.

[0006] Conventional injectors are configured to introduce cooling air into the corresponding cavity or cavities in a direction substantially parallel to an axis of rotation of the moving wheels in the direction of the latter.

[0007] Such axial injectors generally do not allow proper control of the flow and distribution of cooling air, which reduces the performance of the ventilation and more generally of the turbomachine. Description of the invention

[0008] The invention aims to improve the ventilation performance of a turbomachine turbine, to reduce the mass of the turbine and to simplify its assembly.

[0009] A particular object of the invention is to provide a compact injector capable of efficiently cooling a two-stage turbine that is counter-rotating or rotating in the same direction.

[0010] To this end, a cooling air injector for a turbomachine turbine is proposed, extending around a central longitudinal axis and comprising injection channels circumferentially distributed relative to each other around the axis, each injection channel comprising an internal cavity having an inlet end portion provided with an air inlet and an outlet end portion provided with an air outlet. According to the invention, the injection channels are distributed in a first and a second series, the outlet end portion of each of the injection channels of the first series being directed longitudinally towards a first side of the injector and oriented tangentially to the axis in a first direction, the outlet end portion of each of the injection channels of the second series being directed longitudinally towards a second side of the injector opposite to the first side and oriented tangentially to the axis in the first direction or in a second direction opposite to the first direction.

[0011] Such an injector makes it possible to simultaneously cool two disks located longitudinally on either side of the injector, in particular in a turbine comprising at least two stages.

[0012] The injector of the invention makes it possible in particular to inject cooling air in such a way as to produce a circular movement around the longitudinal central axis, in particular in the same direction of rotation as one or more movable wheel discs towards which the cooling air is directed longitudinally.

[0013] This results in a decrease in the total relative temperature of the cooling air and better cooling of the disks.

[0014] In one embodiment, the injector comprises an annular ring extending around the longitudinal central axis, the injection channels extending in projection relative to the annular ring.

[0015] Such an architecture makes it possible to form injection channels without them being hollowed out or formed within a massive structure, which makes it possible to reduce the amount of material forming the injector.

[0016] It is estimated that the invention thus makes it possible to divide the mass of a conventional injector by at least half.

[0017] In particular, protruding injection channels can be formed using a relatively small amount of material.

[0018] For example, each of the injection channels may include a wall delimiting the corresponding internal channel.

[0019] Preferably, each of the injection channels includes a wall of constant thickness along the corresponding internal channel, i.e. between the inlet and outlet of this internal channel.

[0020] In one embodiment, the annular crown includes openings each forming the entrance to one of the respective injection channels.

[0021] The annular ring can in particular fulfill a function of supporting the injection channels and fixing the injector on a part of the turbine such as a distributor of this turbine.

[0022] The geometry of the injection channels can be relatively complex in order to introduce air in a direction of intake different from said injection direction, for example in a radial intake direction.

[0023] Thus, in one embodiment, the inlet of the inlet end portion of each of the injection channels defines an intake direction which is oriented in a radial direction with respect to the longitudinal central axis, each of the injection channels comprising an intermediate angled portion connecting the inlet end portion and the outlet end portion.

[0024] In one embodiment, the internal cavity of each of the injection channels has a cross-section having an area that decreases from the inlet to the outlet.

[0025] The reduction in cross-section of the internal cavity of the injection channels makes it possible to accelerate the airflow and, in combination with the orientation of their outlet end portion, to obtain a cooling air displacement velocity whose tangential component is greater than that resulting from a conventional injector.

[0026] Preferably, the decrease in the cross-sectional area of ​​the internal cavity of each of the injection channels follows a monotonic function.

[0027] In other words, the cross-section of the internal cavity of each of the injection channels preferably has an area that only decreases from the inlet to the outlet.

[0028] The ratio of the area of ​​the inlet section to the area of ​​the outlet section is, for example, greater than 1 and less than or equal to 10.

[0029] In one embodiment, the injection channels of the first and second series are respectively distributed so as to form several pairs of injection channels circumferentially distributed around the longitudinal central axis, the injection channels of each of the pairs being arranged head-to-tail.

[0030] The invention also relates to a turbine for a turbomachine comprising an injector as defined above.

[0031] The turbine can be a high-pressure turbine, for example for an aircraft propulsion system turbojet.

[0032] In one embodiment, the turbine includes a distributor and an injector as defined above, the distributor comprising one or more cavities in fluidic communication with the internal cavity of each of the injector's injection channels so as to be able to introduce into the internal cavity of each of the injection channels, via the corresponding inlet, air circulating in the cavities of the distributor.

[0033] In one embodiment, the turbine comprises an upstream wheel, a downstream wheel and an injector as defined above, the injector extending longitudinally between the upstream wheel and the downstream wheel.

[0034] The embodiment in which the outlet end portion of the injection channels of each of the first and second series is oriented tangentially in the first direction is particularly suitable for such a turbine in which the upstream and downstream runners rotate relative to each other in the same direction of rotation.

[0035] The embodiment in which the outlet end portion of the injection channels of the first series is oriented tangentially in the first direction while the outlet end portion of the injection channels of the second series is oriented tangentially in the second direction is particularly suitable for such a turbine in which the upstream and downstream runners rotate relative to each other in a different direction of rotation.

[0036] The invention also relates to a turbomachine comprising a turbine as defined above, in particular a twin-body turbomachine for an aircraft propulsion system, an aircraft propulsion system comprising such a turbomachine and an aircraft comprising such a propulsion system.

[0037] According to another aspect, the invention relates to a method for manufacturing an injector as defined above.

[0038] Preferably, this process is an additive manufacturing process, that is to say, it includes at least one additive manufacturing step.

[0039] The invention thus makes it possible to reduce the number of assembly parts.

[0040] In particular, when the injector comprises two sets of injection channels such As defined above, the process may include a first step of additive manufacturing of a first part of the injector including the first set of injection channels, a second step of additive manufacturing of a second part of the injector including the second set of injection channels, and a third step of assembling the first and second parts of the injector together.

[0041] The injector, in particular when it comprises a single series of injection channels, can also be manufactured in one piece, by additive manufacturing.

[0042] More generally, the invention thus makes it possible to reduce the production cost of such an injector and to reduce the mass of the turbine and the ventilation circuit of the turbomachine while improving the ventilation performance and consequently the performance of the turbomachine.

[0043] Other advantages and features of the invention will become apparent from the following detailed, non-limiting description. Brief description of the drawings

[0044] The following detailed description refers to the attached drawings on which:

[0045] [Fig.1] is a schematic view of an aircraft propulsion assembly according to the invention;

[0046] [Fig.2] is a schematic view of a single-stage, single-rotational two-stage turbine according to the invention;

[0047] [Fig.3] is a schematic view of a two-stage counter-rotating turbine according to the invention;

[0048] [Fig.4] is a schematic perspective view of an injector according to a first embodiment of the invention, detailing more specifically the geometry of an injection channel belonging to the injection assembly;

[0049] [Fig.5] is a schematic view of the injection channel of the [Fig.3];

[0050] [Fig.6] is a schematic view of the injector of [Fig.3];

[0051] [Fig.7] is a schematic perspective view of the injector of [Fig.3];

[0052] [Fig.8] is a schematic view of an injector conforming to a second mode of realization of the invention. Detailed description of implementation methods

[0053] Figures 1 to 7 include an LRT reference frame defining respectively longitudinal (or axial) L, radial R and tangential (or circumferential) T directions orthogonal to each other.

[0054] Figure 1 shows a propulsion unit 1 of an aircraft comprising a turbomachine 2 enclosed by a nacelle 3. In this example, the turbomachine 2 is a twin-spool, twin-flow turbojet.

[0055] Subsequently, the terms "upstream" and "downstream" are defined with respect to a direction DI of gas flow through the propulsion assembly 1 when it generates thrust. The flow direction DI is parallel to the longitudinal direction L.

[0056] The turbojet 2 has a longitudinal central axis A1 and comprises, 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 unit 1 through an air inlet upstream of the nacelle 3, passes through the fan 4, and then splits into a central primary flow 10A and a secondary flow 10B. The primary flow 10A flows in a primary gas circulation channel 1IA passing through the compressors 5 and 6, the combustion chamber 7, and the turbines 8 and 9. The secondary flow 10B flows in a secondary channel 11B surrounding the gas generator and radially delimited outwards by the nacelle 3.

[0058] In a manner known per se, a turbine such as the high-pressure turbine 8 or the low-pressure turbine 9 comprises one or more stages, each comprising a distributor and a runner. The distributor of a stage comprises a ring of stator blades configured to divert the primary flow 10A from the combustion chamber 7 to the runner blades of the same stage, thereby driving the runner into rotation. For each of the turbines 8 and 9, the distributor(s) form a turbine stator and the runner(s) form a turbine rotor.

[0059] Figure [Fig. 2] illustrates an example of a high-pressure turbine architecture 8.

[0060] The turbine 8 of [Fig. 2] comprises, from upstream to downstream, an upstream rotating wheel 15, a distributor 16 and a downstream moving wheel 17.

[0061] The upstream moving wheel 15 belongs to a first stage of the turbine 8. The distributor 16 and the downstream moving wheel 17 belong to a second stage of the turbine 8.

[0062] The movable wheels 15 and 17 each comprise a disc 18 and 19, respectively.

[0063] In this example, disks 18 and 19 are both fixed to a shaft 20 of the turbojet 2 such as a high-pressure shaft, so that the movable wheels 15 and 17 are driven in the same direction of rotation around the AL axis

[0064] The turbine 8 of [Fig.2] thus forms a single-rotational turbine.

[0065] On either side of the distributor 16, organs 22 ensure the sealing of a ventilation cavity 25 which extends radially inwards relative to the primary vein 11 A.

[0066] In this example, the components 22 are conventional labyrinth seals comprising an abradable material 23 carried by the distributor 16 and wipers 24 integral with the discs 18 and 19 rotating about the axis AL

[0067] The ventilation cavity 25 extends longitudinally between the movable wheels 15 and 17 so that a part of the discs 18 and 19 is exposed to the gases present in the ventilation cavity 25.

[0068] The turbomachine 2 includes a ventilation circuit for drawing air from the primary flow 1 IA in the high-pressure compressor 6 and conveying this air to the turbine 8 for ventilation. In this description, the air thus conveyed is referred to as "cooling air".

[0069] The ventilation circuit includes radial cavities 27 radially passing through one or more vanes of the distributor 16 and being in fluidic communication with a radially external annular cavity (not shown) supplied with cooling air.

[0070] The turbine 8 further includes an injector 30 fixed to the distributor 16 so as to extend into the ventilation cavity 25.

[0071] The injector 30 is configured to inject into the ventilation cavity 25 cooling air from the radially external cavity and routed to the injector 30 via the radial cavities 27 of the distributor 16.

[0072] In a manner known per se, the cooling air injected into the ventilation cavity 25 is intended to cool the discs 18 and 19 and more generally the moving wheels 15 and 17 and contributes to the sealing of the ventilation cavity 25 with respect to the primary vein 11 A.

[0073] Fig. 3 illustrates another turbine architecture 8 which differs from that of Fig. 2 in that the disk 18 is rotationally fixed around the axis Al of a first shaft 20 such as a high-pressure shaft while the disk 19 is rotationally fixed around the axis Al of a second shaft 32 such as a low-pressure shaft.

[0074] In this example, the high-pressure shaft 20 is driven in rotation around the axis Al in a first direction of rotation and the low-pressure shaft 32 is driven in rotation around the axis Al in a second direction of rotation opposite to the first direction of rotation.

[0075] As a result, the discs 18 and 19 of [Fig.3] rotate in opposite directions relative to each other around the axis Al, forming a counter-rotating turbine 8.

[0076] The invention relates more specifically to the structure of the injector 30 and its manufacture, it being understood that the following description applies by analogy to turbines having a different architecture from that of figures 2 and 3 and / or being intended for a different engine than the turbomachine 2 of [Fig.1].

[0077] Figures 4 to 7 show an injector 30 according to a first embodiment of the invention.

[0078] With reference to figures 6 and 7, the injector 30 has an overall annular shape extending around a central longitudinal axis which in this example corresponds to the aforementioned axis Al when the injector 30 is connected to the distributor 16.

[0079] More specifically, the injector 30 comprises an annular ring 34 extending around the axis Al and injection channels 35 circumferentially distributed relative to each other around the axis AL

[0080] In this example, the annular ring 34 comprises two L-shaped brackets 36 and 37.

[0081] The first bracket 36 comprises a radial leg 38 and an axial leg 39. Similarly, the second bracket 37 comprises a radial leg 40 and an axial leg 4L

[0082] The brackets 36 and 37 are fixed to each other, for example by brazing, by their radial tab 38 / 40 so as to present in a plane LR a “T” section.

[0083] The injector 30 is fixed to the distributor 16, for example by brazing, by the axial lugs 39 and 41 of the brackets 36 and 37.

[0084] With reference to [Fig. 6], the injection channels 35 in this example form two series. The injection channels 35 of the first series are connected to the first bracket 36. The injection channels 35 of the second series are connected to the second bracket 37.

[0085] Figures 4 and 5 show more precisely the geometry of an injection channel 35, belonging in this case to the first series. In [Fig. 4], the injection channel 35 of the first series is the one located towards the front, on the left of this figure.

[0086] The following description relates to this particular injection channel 35 of Figures 4 and 5 and applies by analogy to the other injection channels 35.

[0087] With reference to [Fig.4], the injection channel 35 extends in projection relative to the annular ring 34, in this case relative to the first bracket 36.

[0088] More specifically, the injection channel 35 includes a wall connected to the axial leg 39 of the first bracket 36 and extending radially inwards relative to the axial leg 39.

[0089] The wall forming the injection channel 35 delimits a hollow space which forms an internal cavity extending along the injection channel 35.

[0090] In this example, the wall of the injection channel 35 has a constant thickness along the injection channel 35.

[0091] The injection channel 35 or, more precisely, the internal cavity of the injection channel 35 comprises an inlet end portion 50, an intermediate portion 51 and an outlet end portion 52.

[0092] The inlet end portion 50 is connected to the axial lug 39 of the first bracket 36 and defines an inlet direction A2 which has a radial component, that is to say a component orthogonal to the longitudinal central axis AL

[0093] The outlet end portion 52 defines an injection direction A3 which has a longitudinal component and a tangential component.

[0094] The intermediate portion 51, which connects the inlet end portion 50 and the outlet end portion 52, is angled.

[0095] Thus, the injection channel 35 and its internal cavity extend along a curved line.

[0096] The axial leg 39 of the first bracket 36 includes an opening 54, radially passing through this axial leg 39, so as to form an intake opening, or inlet, putting the internal cavity of the injection channel 35 in fluidic communication with a space delimited radially inwards by the ring 34.

[0097] The outlet end portion 52 is provided with an injection opening 55, or outlet, putting the internal cavity into fluidic communication with a space delimited radially outwards by the ring 34.

[0098] When the injector 30 is connected to the distributor 16, the internal cavity of the injection channel 35 is in fluidic communication with the radial cavity or cavities 27 of the distributor 16 so as to be able to introduce cooling air into this internal cavity via the inlet 54 and inject this cooling air into the ventilation cavity 25 via the outlet 55.

[0099] In this example, the injection direction A3 extends in a plane parallel to the longitudinal direction L and tangential direction T.

[0100] With reference to [Fig.5], the tangential component of the injection direction A3 is translated by the fact that it is oblique with respect to a plane PI passing through the longitudinal central axis Al and comprising a point belonging both to the section defined by the outlet 55 and to the injection direction A3.

[0101] It is preferred that the angle Cl between the injection direction A3 and the plane PI be less than 50°.

[0102] The inlet 54 of the injection channel 35 has a cross-section having substantially the shape of a parallelogram surmounted by a circular shape. Preferably, the circular shape of the inlet 54 has a radius of less than 5 mm.

[0103] In another embodiment, not shown, the section of the inlet 54 may have a substantially triangular shape.

[0104] The outlet 55 of the injection channel 35 has a section having substantially a rectangular shape with rounded edges.

[0105] The area of ​​the inlet section 54 is greater than the area of ​​the outlet section 55.

[0106] In this example, the section of the internal cavity of the injection channel 35 has a area which decreases progressively, monotonically, from the entrance 54 to the exit 55.

[0107] The shape of the internal cavity section evolves along the intermediate portion 51 so as to gradually change from the shape of the inlet section 54 to that of the outlet section 55.

[0108] Given the geometry of the injection channel 35, the cooling air introduced into the internal cavity through the inlet 54 has a velocity that, as it moves through the inlet end portion 50, exhibits primarily a radial component and, to a lesser extent, a tangential component. As it passes through the intermediate portion 51, the radial component of the air velocity decreases while its axial component becomes positive. The outlet end portion 52 allows the air to be directed along the injection direction A3 so that the air velocity has both an axial and a tangential component.

[0109] In the embodiment of Figures 4 to 7, the outlet end portion 52 of each of the injection channels 35 of the first series - for example the injection channel 35 located towards the front, on the left, in [Fig. 4] - is directed longitudinally towards a first side of the injector 30 and tangentially in a first direction. The outlet end portion of each of the injection channels 35 of the second series - for example the rear, right-hand injection channel 35 in [Fig.4] - is directed longitudinally towards a second side of the injector opposite to the first side and tangentially in a second direction opposite to the first direction.

[0110] This embodiment is particularly suited to a configuration such as that illustrated in [Fig.3] in which the upstream moving wheel 15 and the downstream moving wheel 17 rotate relative to each other in a different direction of rotation around the longitudinal central axis Al.

[0111] The upstream wheel 15 of the turbine 8 of [Fig.3] rotates in a first direction while the downstream wheel 17 rotates in a second opposite direction.

[0112] In this example, the outlet end portion 52 of each of the injection channels 35 of the first series is directed longitudinally towards the first moving wheel 15, tangentially in the first direction. The outlet end portion 52 of each of the injection channels 35 of the second series is directed longitudinally towards the second moving wheel 17, tangentially in the second direction.

[0113] [Fig.8] shows an injector 30 according to a second embodiment of the invention which differs from that of [Fig.6] in that the outlet end portions 52 of the set of injection channels 35, both of the first and second series, are tangentially oriented in the same direction.

[0114] The description of the embodiment of Figures 4 to 7 above applies by analogy to the embodiment of [Fig.8].

[0115] The embodiment of [Fig.8] is particularly suited to a configuration such as that illustrated in [Fig.2] in which the upstream movable wheel 15 and the downstream movable wheel 17 rotate in the same direction of rotation around the longitudinal central axis Al, by convention a first direction.

[0116] In this example, the outlet end portion 52 of each of the injection channels 35 of the first series is directed longitudinally towards the first rotating wheel 15, tangentially in the first direction. The outlet end portion 52 of each of the injection channels 35 of the second series is directed longitudinally towards the second rotating wheel 17, tangentially in the second direction.

[0117] In each of these examples, the cooling airflow exiting the injection channels 35 of the injector 30 circulates circumferentially in the same direction of rotation as the disk 18 or 19 towards which this corresponding flow is directed, which improves the cooling of the disks 18 and 19.

[0118] Naturally, the number of injection channels 35 and the dimensions of their internal channel, in particular the area of ​​the outlet cross-section 55, are determined according to the flow rate required for cooling the disks 18 and 19, for preserving the sealing of the ventilation cavity 25 and more generally to the ventilation of the turbine 8.

[0119] The invention covers numerous embodiments based on the principles just described. For example, the injector 30 can include in the same series different types of injection channels 35 which are distinguished from each other by the relative orientation of the injection direction A3 and / or by the dimensions of their internal cavity, their inlet 54 and / or their outlet 55.

[0120] Regarding the manufacture of the injector 30, it is advantageously produced by additive manufacturing.

[0121] In the examples described above, each of the brackets 36 and 37 is produced separately by additive manufacturing, starting with the radial leg 38 / 40 and ending with the outlet end 52 of the injection channels 35.

[0122] The brackets 36 and 37 are then fixed to each other by brazing so as to form the injector 30, which can then be fixed to the distributor 16 of the turbine 8.

Claims

Demands

1. Cooling air injector (30) for a turbomachine turbine (8, 9) (2), extending around a central longitudinal axis (Al) and comprising injection channels (35) circumferentially distributed with respect to each other around the axis (Al), each of the injection channels (35) comprising an internal cavity which has an inlet end portion (50) provided with an air inlet (54) and an outlet end portion (52) provided with an air outlet (55), characterized in that the injection channels (35) are distributed in a first and a second series, the outlet end portion (52) of each of the injection channels (35) of the first series being directed longitudinally (L) towards a first side of the injector (30) and oriented tangentially (T) with respect to the axis (Al) in a first direction,the outlet end portion (52) of each of the injection channels (35) of the second series being directed longitudinally (L) towards a second side of the injector (30) opposite to the first side and oriented tangentially (T) with respect to the axis (Al) in the first direction or in a second direction opposite to the first direction, comprising an annular ring (34) extending around the central longitudinal axis (Al), the injection channels (35) projecting outwards from the annular ring (34).

2. Injector (30) according to claim 1, in which the annular ring (34) includes openings each forming the inlet (54) of one of the respective injection channels (35).

3. Injector (30) according to any one of claims 1 or 2, wherein the inlet (54) of the inlet end portion (50) of each of the injection channels (35) defines an intake direction (A2) which is oriented in a radial direction (R) with respect to the longitudinal central axis (Al), each of the injection channels (35) comprising an intermediate angled portion (51) connecting the inlet end portion (50) and the outlet end portion (52).

4. Injector (30) according to any one of claims 1 to 3, wherein the internal cavity of each of the injection channels (35) has a cross-section having an area that decreases from the inlet (54) to the outlet (55), the ratio of the cross-sectional area of ​​the inlet (54) on the area of ​​the section of the outlet (55) being preferably greater than 1 and less than or equal to 10.

5. Injector (30) according to any one of claims 1 to 4, wherein the injection channels (35) of the first and second series are respectively distributed so as to form several pairs of injection channels (35) circumferentially distributed around the longitudinal central axis (Al), the injection channels (35) of each of the pairs being arranged head-to-tail.

6. Turbine (8, 9) for turbomachine (2), comprising a distributor (16) and an injector (30) according to any one of claims 1 to 5, the distributor (16) comprising one or more cavities (27) in fluidic communication with the internal cavity of each of the injection channels (35) of the injector (30) so as to be able to introduce into the internal cavity of each of the injection channels (35), via the corresponding inlet (54), air circulating in the cavity or cavities (27) of the distributor (16).

7. Turbine (8, 9) for turbomachine (2), in particular according to claim 6, comprising an upstream wheel (15), a downstream wheel (17) and an injector (30) according to any one of claims 1 to 5, the injector (30) extending longitudinally (L) between the upstream wheel (15) and the downstream wheel (17).

8. Turbomachine (2) for aircraft propulsion assembly (1), comprising a turbine (8, 9) according to claim 6 or 7.

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