Intermediate housing for turbomachine with air discharge system equipped with an annular manifold

Abstract

An intermediate housing (40) for a turbomachine includes: an air discharge system comprising orifices (60) formed in a ferrule (54) communicating a section of annular vein (PV) with an off-vein cavity (59), and, for each of the orifices, a VBV gate (62) mounted movable between a closed position and an open position of the orifice; and an air manifold (70) defining a manifold cavity (73) extending annularly around an axis (28) of the intermediate housing. The air collector (70) is provided with an annular row of air inlet openings (74) connecting the non-venous cavity (59) to the collector cavity (73) for introducing air from the sampling orifices (60), and air evacuation means configured to evacuate air from the collector cavity (73) out of the non-venous cavity. Figure for abbreviation: Figure 6

Description

Title of the invention: Intermediate housing for a turbomachine with an air discharge system equipped with an annular manifold. Technical field

[0001] The present invention relates to the field of turbomachinery in which an airflow passes through at least two consecutive compressors connected to each other by a casing, commonly referred to as an intermediate casing, and in which such a casing includes an air discharge system. The turbomachinery concerned by the invention are in particular those intended for aircraft propulsion. Prior art

[0002] A multi-spool turbomachine comprises at least two consecutive compressors connected by an intermediate casing, and driven respectively by two independent shafts. In the case of a twin-spool turbomachine, these are the low-pressure compressor and the high-pressure compressor, and the intermediate casing that connects them is commonly referred to as the intermediate casing.

[0003] Such compressors are traversed by the same flow of air, but their rotational speeds vary in different proportions. Consequently, at idle, the first compressor tends to deliver more air than the second compressor.

[0004] To ensure proper compressor operation, it is necessary to evacuate excess air from the first compressor at its outlet, before the inlet of the second compressor. This is achieved by means of an air discharge system, also known as a VBV system (for "Variable Bleed Valve" in Anglo-Saxon terminology), designed to open air discharge valves, also called VBV valves or gates, on command at the intermediate casing. Another function performed by such a system is to evacuate any debris and particles present in the airflow (water, hail, ice, gravel, etc.) so as to prevent such debris from reaching the combustion chamber located downstream of the second compressor.

[0005] In a known configuration, the VBV gates are associated with air exhaust ducts such that when the valves are open, the valves expel air directly towards the respective inlets of the air exhaust ducts. These ducts have outlets arranged radially outwards relative to the inlets to vent the air out of the turbomachine core, for example into a secondary or tertiary flow channel or outside the turbomachine.

[0006] However, such air exhaust ducts occupy a considerable amount of space within the turbomachine, particularly when the shape of the flow channel of secondary or tertiary flow intended to receive the evacuated air, or the shape of the external fairing of the turbomachine in the case of ejection outside the latter, requires that the outlets of the air evacuation ducts be positioned significantly further radially outwards than the inlets of these ducts.

[0007] Moreover, in cases where the air evacuated by the discharge system is intended to be introduced into another internal flow of the turbomachine, such as a secondary or tertiary flow, evacuating this air through discrete ducts, whose outlets are necessarily of limited cross-section, tends to induce undesirable aerodynamic disturbances within this other internal flow.

[0008] In this context, there is a need for an intermediate housing for turbomachine including an optimized air discharge system. Description of the invention

[0009] The invention relates to an intermediate housing comprising an improved air discharge system.

[0010] To this end, it proposes an intermediate housing for a turbomachine, comprising: • a ferrule extending annularly around an axis of the intermediate casing and externally delimiting a section of annular vein intended for the flow of an air stream between two compressors of a turbomachine in a direction going from an upstream side of the intermediate casing to a downstream side of it; • an outer wall of the hub extending annularly around the ferrule so as to define, between them, an off-vein cavity; • an upstream flange and a downstream flange, each annular in shape, each connecting the ferrule to the outer wall of the hub, so as to delimit respectively an upstream side and a downstream side of the non-vein cavity; and • an air discharge system comprising an annular row of sampling orifices formed in the ferrule to connect the annular vein segment with the non-vein cavity, and, for each of the orifices, a corresponding VBV gate mounted movable between a closed position, in which the VBV gate closes the sampling orifice, and an open position, in which the VBV gate allows air to flow through the sampling orifice.

[0011] According to the invention, the intermediate housing comprises an air manifold defining a manifold cavity extending annularly around the axis of the intermediate housing, the air manifold being provided with an annular row of air inlet openings connecting the off-vein cavity to the manifold cavity to introduce air from sampling ports, and air evacuation means configured to evacuate air from the collector cavity out of the non-vein cavity.

[0012] The air manifold offers the general advantage of a reduced axial footprint compared to air exhaust ducts. This advantage is even more pronounced when the air exhaust must be located far from the axis of the intermediate housing.

[0013] Furthermore, the air manifold allows for the temporary storage of air drawn in by the air discharge system. In cases where this air is intended to be introduced into another internal airflow within the turbomachine that contributes to the overall thrust of the turbomachine and / or to the cooling of turbomachine components, this results in an additional advantage: better control over how the drawn air is introduced into this other flow. This advantage stems not only from the homogenization of the air within the air manifold but also from the inherent ability of the air manifold to optimize the configuration of the air discharge means, so as to minimize the aerodynamic disturbances resulting from the discharge of the drawn air.

[0014] The air manifold thus makes it possible to limit the negative impact of the air discharge system on the performance of the turbomachine and to ensure good operability of the components located upstream and downstream of the air discharge system.

[0015] In preferred embodiments of the invention, the air evacuation means are defined through a radially external end of the air collector.

[0016] The radially external end of the air collector preferably comprises an annular row of air outlet openings constituting said air evacuation means.

[0017] In preferred embodiments of the invention, the air manifold comprises a manifold flange, extending coaxially to - and opposite - the downstream flange, so as to define the manifold cavity between the downstream flange and the manifold flange.

[0018] Preferably, the collector flange has a radially internal end connected to the downstream flange so as to close a radially internal end of the collector cavity.

[0019] Preferably, the collector flange is arranged downstream of the downstream flange.

[0020] In preferred embodiments of the invention, the radially external end of the air manifold is defined as level with the outer wall of the hub.

[0021] The invention also relates to an aircraft turbomachine, comprising at least two compressors separated from each other by an intermediate casing of the type defined above.

[0022] In preferred embodiments of the invention, said annular vein section delimited externally by the ferrule is a primary vein section, and the outer wall of the hub internally delimits another annular vein intended for the flow of a bypass airflow within the turbomachine. Brief description of the drawings

[0023] The invention will be better understood, and other details, advantages and features thereof will become apparent from the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:

[0024] [Fig-1] is a schematic axial cross-sectional view of a turbomachine;

[0025] [Fig.2] is a schematic perspective view of an intermediate housing of the turbomachine of the [Fig.1], shown in isolation;

[0026] [Fig.3] is a partial schematic half-view in axial section and larger scale of a turbomachine such as the turbomachine of [Fig.1], illustrating part of an intermediate casing such as that of [Fig.2] in a known configuration, with a VBV gate in the closed position;

[0027] [Fig.4] is a view similar to [Fig.3], showing the VBV door in the open position;

[0028] [Fig.5] is a schematic perspective view of an air exhaust duct forming part of the intermediate housing of Figures 3 and 4, from which outlet fins have been removed;

[0029] [Fig.6] is a view similar to [Fig.4], illustrating an intermediate housing according to a preferred embodiment of the invention;

[0030] [Fig.7] is a schematic axial cross-sectional view, from downstream, of the intermediate housing of the [Fig.6], lacking a collector flange;

[0031] [Fig.8] is a schematic axial cross-sectional view, from downstream, of the intermediate housing of the [Fig.6], with the collector flange.

[0032] Throughout these figures, identical references may designate identical or analogous elements. Detailed presentation of preferred embodiments

[0033] Fig. 1 illustrates a turbomachine 10, for example a twin-spool turbofan engine for aircraft, generally comprising a fan 12 for the intake of an airflow Fl which divides downstream of the fan into a primary flow F2 circulating in a primary flow channel, hereinafter referred to as the primary flow PV, within a core of the turbomachine, and a secondary flow F3 bypassing this core in a secondary flow channel, hereinafter referred to as the secondary flow SV.

[0034] The core of the turbomachine generally comprises a low-pressure compressor 14, a high-pressure compressor 16, a combustion chamber 18, a high-pressure turbine 20 and a low-pressure turbine 22.

[0035] The respective rotors of the high-pressure compressor and the high-pressure turbine are connected by a shaft referred to as the "high-pressure shaft," while the respective rotors of the low-pressure compressor and the low-pressure turbine are connected by a shaft referred to as the "low-pressure shaft," in a well-known manner. The turbomachine is enclosed by a nacelle 24 surrounding the secondary flow SV. Furthermore, the turbine rotors are mounted to rotate about a shaft 28 of the turbomachine.

[0036] Throughout this description, the axial direction X is the direction of the axis 28. A cylindrical coordinate system centered on the axis 28 is further considered, in which a radial direction "R" is at every point orthogonal to and passing through the axis 28, while an ortho-radial or circumferential direction "C" is at every point orthogonal to the radial direction R and to the axis 28. A transverse plane is a plane orthogonal to the axis 28. The terms "internal" and "external" refer respectively to a relative proximity and a relative distance of an element from the axis 28. Finally, the "upstream" and "downstream" directions are defined with reference to the general direction FD of the gas flow in the primary PV and secondary SV sections of the turbomachine, along the axial direction X.

[0037] The turbomachine includes an intermediate casing 40 arranged axially between the low-pressure compressor 14 and the high-pressure compressor 16, and shown isolated in [Fig. 2]. In the non-limiting context of a twin-spool turbojet engine, such an intermediate casing 40 is sometimes referred to as an intermediate casing.

[0038] The intermediate housing 40 comprises, for example, an annular outer housing wall 42, a hub 44, guide vanes 46 extending from the outer housing wall 42 to the hub 44 and / or structural arms 48 and 50 rigidly connecting the outer housing wall 42 to the hub 44. The outer housing wall 42 extends annularially around a section or segment of the secondary vein SV, while the hub 44 extends radially inside the section of the secondary vein SV, and radially outside with respect to a section or segment of the primary vein PV.

[0039] The hub 44 includes an outer hub wall 52 which extends annularily so as to internally delimit the section of the secondary vein SV, an intermediate hub wall, simply referred to as ferrule 54 in the following, which extends annularily so as to externally delimit the section of the primary vein PV, an inner hub wall 55 which extends annularily so as to internally delimit the section of the primary vein PV, and other arms 56 connecting the ferrule 54 to the inner hub wall 55.

[0040] With reference to [Fig. 3], the hub 44 comprises an upstream flange 57 and a downstream flange 58, each annular in shape and each connecting the ferrule 54 to the outer wall of the hub 52, so as to respectively define an upstream side and a downstream side of an off-flow cavity 59 defined between the ferrule 54 and the outer wall of the hub 52. This off-flow cavity 59 is sometimes referred to as an inter-flow cavity in the context of a twin-flow or triple-flow turbomachine. The various annular walls and flanges constituting the intermediate housing 40 are, of course, centered along an axis of this housing which generally coincides with the axis 28 of the turbomachine. The upstream flange 57 and downstream flange 58 extend, of course, in a generally transverse manner to the axis 28, to connect the ferrule 54 to the outer wall of the hub 52.

[0041] Furthermore, the intermediate housing 40 includes an air discharge system. This system comprises an annular row of sampling orifices 60 formed in the ferrule 54, one of which is visible in the cross-sectional plane of [Fig. 3]. Each sampling orifice 60 is thus flush with the segment of the primary vein PV and opens into the non-vein cavity 59.

[0042] In addition, for each of these sampling orifices 60, the air discharge system includes a corresponding VBV door 62 pivotally mounted about a corresponding pivot axis 64 on a part of the intermediate housing 40, so that the VBV door 62 is movable between a closed position, in which the VBV door 62 closes the sampling orifice 60 ([Fig.3]), and an open position, in which the VBV door 62 allows air to circulate through the sampling orifice 60 ([Fig.4]).

[0043] The turbojet engine naturally includes an actuation mechanism to control the pivoting of the VBV 62 doors. This actuation mechanism may be of a conventional type and is not shown in the figures for clarity. The configuration and implementation of such an actuation mechanism, as well as the design of such VBV doors, fall within the expertise of those skilled in the art. Each VBV 62 door has a means of connection to the actuation mechanism, which may also be of a conventional type and is likewise not shown in the figures.

[0044] The downstream flange 58 is provided with a plurality of air outlet orifices 65, for example distributed in an annular row of such orifices, each opening into the non-vein cavity 59.

[0045] Each VBV 62 advantageously comprises a guide duct 63 configured to guide at least a portion of the air, taken from the corresponding sampling orifice 60, towards a corresponding air outlet orifice 65.

[0046] In the known configuration shown in Figures 3 and 4, each of the air outlet orifices 65 is associated with a corresponding exhaust duct 66, one of which is shown isolated in [Fig. 5]. There is thus an annular row of such ducts 66, one of which is visible in the cross-sectional plane of [Fig. 3] along with the corresponding air outlet orifice 65.

[0047] Each of the discharge conduits 66 has an inlet 66A arranged to receive air, possibly laden with debris, from the off-vein cavity 59, through the corresponding orifice 65, and has an outlet 66B arranged to discharge this air into the secondary vein SV. The outlet 66B is typically arranged to integrate aerodynamically with the wall that internally delimits the secondary vein SV, in continuity with the outer hub wall 52. The outlet 66B is generally provided with outlet fins 68 (Figures 3 and 4) configured to deflect the airflow from the conduit 66 downstream and thus limit disturbances to the secondary flow F3.

[0048] However, the conduits 66 occupy a considerable amount of space within the turbomachine, particularly in cases where the shape of the secondary flow requires the outlets 66B of the exhaust conduits 66 to be positioned significantly further from the axis 28 than the inlets 66A of these conduits. The radial, but also axial, footprint of these conduits 66 is then significantly increased, which is all the more detrimental.

[0049] Furthermore, in cases where the outlets 66B of the ducts 66 open into another internal airflow of the turbomachine, as in the illustrated example where this other airflow is the secondary flow F3, the air injection through the outlets 66B, which is relatively circumferentially localized, tends to generate localized disturbances in this other airflow. The localized nature of the air introduction into this other flow is due to the fact that the ducts 66 are, by their nature, circumferentially localized, that is to say, their extent in the circumferential direction is limited.

[0050] With reference to Figures 6-8, the invention proposes to define an annular air manifold 70 for receiving air, possibly laden with debris, from the off-vein cavity 59, and expelling this air from this off-vein cavity 59, preferably in a region radially external to the off-vein cavity 59, namely the secondary vein SV in the illustrated example. In other types of turbomachinery, the aforementioned radially external region may be outside the turbomachine.

[0051] For this purpose, the air collector 70 defines a collector cavity 73 extending annularly around the axis 28.

[0052] To define the manifold cavity 73, the air manifold 70 comprises an annular flange, hereinafter referred to as the manifold flange 72, centered along the axis 28 like the other walls described above, and arranged opposite the downstream flange 58, so as to delimit the collector cavity 73 axially between the collector flange 72 and the downstream flange 58. The collector flange 72 therefore also extends globally transversely to the axis 28.

[0053] In the illustrated example, the manifold flange 72 has a radially internal end 72A connected to the downstream flange 58 so as to close a radially internal end 70A of the air manifold 70.

[0054] In this illustrated example, the collector flange 72 is arranged downstream of the downstream flange 58. In such a case, the radially internal end 72A of the collector flange 72 takes, for example, the form of a rim curved upstream.

[0055] The air collector 70 is provided with an annular row of air inlet openings 74 connecting the off-vein cavity 59 to the collector cavity 73 to introduce into the latter the air from the sampling orifices 60, when the VBV doors 62 are in their open position. For this purpose, the air inlet openings 74 are advantageously equal in number to the number of sampling orifices 60 and centered respectively in median axial planes of the sampling orifices 60. In addition, the air inlet openings 74 are advantageously arranged at a radial distance from the axis 28 allowing the openings 74 to be substantially in an extension, respectively, of the guide ducts 63 of the VBV doors 62, so that the air circulating within each of the guide ducts 63 essentially ends up in a corresponding air inlet opening 74.

[0056] In the illustrated example, the air inlet openings 74 are therefore formed in the downstream flange 58, as is more clearly shown in [Fig.7].

[0057] The air collector 70 further includes air evacuation means configured to allow evacuation of the air present in the collector cavity 73 out of the non-vein cavity 59, in the aforementioned radially external region.

[0058] For this purpose, the air collector 70 preferably has an open radially external end 70B defining said air evacuation means.

[0059] More specifically, the radially external end 70B of the air manifold preferably comprises an annular row of air outlet openings 76, one of which is visible in the cross-sectional plane of [Fig. 6]. Each air outlet opening 76 is advantageously provided with outlet fins 68 configured to deflect the airflow from the air manifold 70 downstream and thus limit disturbances to the secondary flow F3.

[0060] Generally, the manifold cavity 73 is preferably closed, disregarding the aforementioned air inlet openings 74 and air outlet means. In particular, the manifold cavity 73 is generally closed radially inwards.

[0061] In operation, when necessary, the VBV 62 gates are deployed to their open positions so as to take a portion of the primary flow F2 and inject it into the collector cavity 73 of the air collector 70 through the air inlet openings 74. The air thus taken is then evacuated radially to the outside, in this case into the secondary vein SV, through the radially external open end 70B of the air collector 70, in this case through the air outlet openings 76.

[0062] The air manifold 70 offers the general advantage of a reduced axial footprint compared to the air exhaust ducts 66 that equip air discharge systems such as that of Figures 3 and 4. This advantage is all the more pronounced when the air exhaust must be far from the axis 28. In such a case, the radial air path along the downstream flange 58 within the air manifold 70 allows for considerably improved axial compactness compared to the oblique path imposed by the ducts 66 of Figures 3 and 4.

[0063] The air manifold 70 also allows for the temporary storage in the manifold cavity 73 of the air drawn in by the air discharge system. In cases where this air is intended to be introduced into another internal airflow of the turbomachine contributing to the overall thrust of the turbomachine and / or is intended for cooling turbomachine components, such as the secondary flow F3 in the illustrated example, this results in an additional advantage consisting of better control over how the drawn air is introduced into this other flow. Indeed, an excessively abrupt introduction of air can negatively impact the operability of the turbomachine. The air manifold 70 helps to limit aerodynamic distortions during the introduction of the drawn air into the aforementioned other flow.This effect results not only from a homogenization of the air within the collector cavity 73 of the collector 70 but also from the possibility, intrinsically offered by the air collector 70, of optimizing the geometry of the air outlet openings 76 or, more generally, of the means of air evacuation, so as to minimize the aerodynamic disturbances resulting from the evacuation of the extracted air.

[0064] The air manifold 70 thus makes it possible to limit the negative impact of the air discharge system on the performance of the turbomachine and to ensure good operability of the components located upstream and downstream of the air discharge system.

[0065] Alternatively, the radially internal end 70A of the air manifold 70 can be defined by the ferrule 54, the air manifold extending in this case radially from the ferrule 54 to the level of the outer wall of the hub 52.

[0066] Alternatively, the collector flange 72 can be arranged upstream of the downstream flange 58.

[0067] According to yet another variant, the air manifold 70 can be axially delimited by the upstream flange 57 and downstream flange 58 and internally delimited by an internal wall to the cavity outside the vein 59 extending annularly around the ferrule 54 between the latter and the external wall of hub 52.

Claims

1. Demands Intermediate housing (40) for turbomachine, comprising: • a ferrule (54) extending annularly around an axis (28) of the intermediate casing and externally delimiting a section of annular vein (PV) intended for the flow of an air stream (F2) between two compressors (14, 16) of a turbomachine in a direction (D) going from an upstream side of the intermediate casing to a downstream side of it; • an outer wall of hub (52) extending annularly around the ferrule (54) so ​​as to define, between them, an off-vein cavity (59); • an upstream flange (57) and a downstream flange (58), each annular in shape, each connecting the ferrule (54) to the outer wall of the hub (52), so as to delimit respectively an upstream side and a downstream side of the non-vein cavity (59); and • an air discharge system comprising an annular row of sampling orifices (60) formed in the ferrule (54) to connect the annular vein segment (PV) with the non-vein cavity (59), and, for each of the orifices (60), a corresponding VBV gate (62) mounted movable between a closed position, in which the VBV gate closes the sampling orifice (60), and an open position, in which the VBV gate allows air to flow through the sampling orifice (60); characterized in that it comprises an air collector (70) defining a collector cavity (73) extending annularly around the axis (28) of the intermediate housing, the air collector (70) being provided with an annular row of air inlet openings (74) connecting the off-vein cavity (59) to the collector cavity (73) to introduce air from the sampling orifices (60), and air evacuation means configured to evacuate the air from the collector cavity (73) out of the off-vein cavity (59).

2. Intermediate housing according to claim 1, wherein the air evacuation means are defined through a radially external end (70B) of the air manifold (70).

3. Intermediate housing according to claim 2, wherein the radially external end (70B) of the air manifold has an annular row of air outlet openings (76) constituting said air evacuation means.

4. Intermediate housing according to any one of claims 1 to 3, wherein the air manifold (70) comprises a manifold flange (72), extending coaxially to - and opposite - the downstream flange (58), so as to define the manifold cavity (73) between the downstream flange (58) and the manifold flange (72).

5. Intermediate housing according to claim 4, in which the collector flange (72) has a radially internal end (72A) connected to the downstream flange (58) so as to close a radially internal end of the collector cavity (73).

6. Intermediate housing according to claim 4 or 5, wherein the collector flange (72) is arranged downstream of the downstream flange (58).

7. Intermediate housing according to any one of claims 1 to 6, wherein the radially external end (70B) of the air manifold (70) is defined to be level with the outer wall of the hub (52).

8. Aircraft turbomachine, comprising at least two compressors (14, 16) separated from each other by an intermediate casing (40) according to any one of claims 1 to 7.

9. Turbomachine according to claim 8, wherein said annular duct section (PV) delimited externally by the shell (54) is a primary duct section, and wherein the outer hub wall (52) internally delimits another annular duct (SV) intended for the flow of a bypass airflow within the turbomachine.

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