Inter-compressor housing for turbomachine with hybrid VBV door and optimized external profile

Abstract

In an inter-compressor assembly for a turbomachine, a VBV gate (62) is pivotally mounted about a pivot axis (64) so ​​as to be movable between a closed position, in which the VBV gate closes an orifice (60), and an open position, in which the VBV gate allows air to flow through an upstream portion (60A) and a downstream portion (60B) of the orifice. The VBV gate (62) is profiled with a downstream surface (76) having a convex axial cross-section from one end to the other, and an angle between the downstream surface (76) and an internal surface (72) of the VBV gate is between 120 and 140 degrees. The risks of air aerodynamically disturbed by the VBV gate in the open position continuing its path and degrading the operation of another downstream component, such as a turbomachine compressor, instead of being drawn into the downstream portion (60B) of the orifice, are thus limited. Figure for the abbreviation: Figure 4

Description

Title of the invention: Inter-compressor housing for turbomachine with hybrid VBV gate and optimized external profile 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 inter-compressor 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 inter-compressor 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 inter-compressor casing that connects them is commonly referred to as the intermediate casing.

[0003] Such compressors are traversed by the same air flow, 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 it enters 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 passages in the inter-compressor housing on command. Another function of such a system is to remove any debris and particles present in the airflow (water, hail, ice, gravel, etc.) to prevent such debris from reaching the combustion chamber located downstream of the second compressor.

[0005] Such an air discharge system comprises an annular row of orifices formed in a ferrule extending annularly around an axis of the inter-compressor casing (coinciding with the axis of the turbomachine) and externally delimiting a section of internal annular channel intended for the flow of air between the two compressors, this flow being for example a primary flow from a turbojet engine.

[0006] Each orifice is thus flush with the internal annular vein section and opens into a corresponding air evacuation passage, the latter opening, for example, into another annular vein such as a flow vein of a secondary flow from the turbojet engine, in which case such an air evacuation passage is sometimes called a cavity inter-vein.

[0007] Furthermore, for each of the aforementioned orifices, the air discharge system includes a corresponding shutter, commonly referred to as a VBV gate. Such a VBV gate is pivotally mounted on a portion of the inter-compressor housing along a determined gate axis so that the VBV gate can be moved between a closed position, in which the VBV gate closes the orifice by masking it, and a fully open position, in which the VBV gate uncovers all or part of the orifice and thus allows air to flow through the orifice.

[0008] Different types of VBV gate actuation systems are known.

[0009] One of these systems is based on actuation by a control ring. This ring, rotating around the axis of the housing, pivots actuators which rotate the VBV gates around their respective axes. The VBV gates open radially inwards into the internal annular vein section, as in [Fig. 1] of document WO2015011392A1, or radially outwards into the corresponding discharge passages, as in document US20090121172A1.

[0010] VBV doors that open in the internal annular vein section must have an aerodynamic shape suitable for closing naturally in the event of a failure in the control mechanism, thus ensuring a failsafe function. This requirement limits the maximum possible opening angle for such VBV doors, and therefore their maximum extraction rate. Furthermore, this requirement imposes a constraint limiting the range of possible shapes for the shell externally delimiting the internal annular vein section, in some cases precluding the use of a shell with an aerodynamically optimal shape.

[0011] Furthermore, in the open position, such a VBV gate generates a "dead zone" of flow, i.e., a flow zone with low axial velocity or conducive to recirculation phenomena, immediately downstream of the VBV gate. This generates pressure losses in the airflow entering the second compressor along flow lines respectively defined downstream of each of the VBV gates. This results in a pressure distortion at the inlet of the second compressor, which can impair the compressor's efficiency and operability.

[0012] VBV doors that open into the air evacuation passage, or intervein cavity, generally require that this passage have an orientation close to the radial direction, so that, even with the addition of a deflector, sometimes called a slide, to guide the evacuated airflow, the flow of the latter can be difficult when the air is laden with water or hail.

[0013] Furthermore, such VBV doors are less efficient at removing debris and quickly extracting air compared to VBV doors with an opening in the internal annular vein section.

[0014] The VBV doors which open in the air evacuation passage have the advantage of not obstructing the annular vein and therefore not inducing a "dead" zone of flow, which makes it possible to limit the impact on the performance of the second compressor at the operating points where it is necessary to evacuate debris and unload the first compressor.

[0015] The applicant's document FR3122903A1 discloses a type of door opening both in the internal annular vein section and in the air evacuation passage and offering both good air and debris extraction performance while ensuring the aforementioned safety function, thus making it possible to reconcile the advantages of the two types of systems mentioned above.

[0016] The present invention is derived from research work aimed at optimizing this latter type of door.

[0017] In particular, the present invention aims to limit the risks that a portion of the primary flow, having been aerodynamically disturbed by an open VBV door, may continue its path within the internal annular vein and enter the aforementioned second compressor, thereby disrupting the operation of the latter, instead of being drawn into the air evacuation passage along the downstream side of the VBV door.

[0018] The invention further aims to limit the risks that air having been extracted from the upstream side of such a VBV gate may return in the internal annular vein section along the downstream side of the VBV gate, under the effect of a "pipe return" type phenomenon, such a phenomenon also being likely to degrade the performance of the second compressor. Description of the invention

[0019] The invention thus relates to an inter-compressor housing comprising an improved air discharge system.

[0020] To this end, it proposes an inter-compressor assembly for turbomachinery, comprising: • an inter-compressor casing comprising: a first ring extending annularly around an axis of the inter-compressor casing and externally delimiting a section of internal annular channel intended for the flow of a primary air stream between two compressors of a turbomachine in a direction going from an upstream side of the inter-compressor casing to a downstream side thereof; a second ring extending annularly around the first ring so as to internally delimit a section of external annular channel intended for the flow of a bypass air stream in said direction; • an air discharge system comprising an annular row of orifices formed in said first ferrule to connect the inner annular vein section with at least one radial air discharge passage opening into the outer annular vein section through at least one discharge grid arranged radially opposite the annular row of orifices, and, for each of said orifices, a corresponding VBV gate mounted on a part of the inter-compressor housing so as to be movable, by pivoting about a gate axis, between a closed position, in which an internal surface of the VBV gate closes the orifice, and a fully open position, in which the VBV gate allows air to flow through the orifice;

[0021] wherein the VBV door has an external profile formed of: • said internal surface, which extends from an upstream edge to a downstream edge thereof; • an external surface which delimits a radially external side of the VBV gate and extends radially outwards in said direction, from an upstream edge of said external surface contiguous to the upstream edge of said internal surface, to a downstream edge of said external surface; • a downstream surface which delimits a downstream side of the VBV gate and extends radially outwards from an internal edge of said downstream surface contiguous to the downstream edge of said internal surface to an external edge of said downstream surface contiguous to the downstream edge of said external surface, said downstream surface having a convex axial cross-section shape from its internal edge to its external edge;

[0022] wherein a defined angle between a tangent to the downstream surface at the level of the latter's inner edge and a tangent to the inner surface at the level of the latter's downstream edge is between 120 and 140 degrees; and

[0023] wherein the gate axis of the corresponding VBV gate is arranged axially between an upstream edge of the orifice and a downstream edge of the orifice at a distance from said upstream and downstream edges such that, in the fully open position, an upstream end portion of the VBV gate protrudes into the internal annular vein section while a downstream end portion of the VBV gate protrudes into the air discharge passage, so that the VBV gate allows air to flow radially outwards towards the grille both through an upstream portion of the air discharge passage defined upstream of the external surface of the VBV gate, and through a downstream portion of the air discharge passage defined between the downstream surface of the VBV gate and a downstream end surface of the internal housing compressor having an internal edge connected to the first ferrule at the level of the downstream edge of each orifice and defining a downstream side of the air evacuation passage.

[0024] Such a VBV gate, due to its "butterfly" type opening kinematics, offers good air and debris suction capabilities while limiting or eliminating the "dead" zone in the flow flowing in the annular vein downstream of such a VBV gate.

[0025] The convex shape of the downstream surface of the VBV gate, and the angle between the internal and downstream surfaces of the VBV gate, make it possible to limit the risks of detachment of the flow along the internal surface and then the downstream surface after passing through the downstream portion of the orifice.

[0026] The invention thus makes it possible to limit the risks that a portion of the airflow circulating in the internal annular vein section, and having been aerodynamically disturbed by the VBV gate in the open position, may continue its path beyond the inter-compressor casing and degrade the operation of another component located downstream of the inter-compressor casing, such as a turbomachine compressor, instead of being drawn into the downstream portion of the air evacuation passage, downstream of the VBV gate.

[0027] The invention also makes it possible to limit the risks of airflow returning to the internal annular vein section via the downstream side of the door, and thus contributes to the performance of the air discharge system.

[0028] In preferred embodiments of the invention, said downstream end surface has a concave axial section and is shaped so that, viewed in axial section, said downstream portion of the air evacuation passage has a flared shape up to the outer edge of said downstream surface when the VBV door is in the fully open position.

[0029] In preferred embodiments of the invention, an inlet section of said downstream portion of the air evacuation passage being defined as the minimum section between the inner edge of said downstream surface of the VBV gate and said downstream end surface of the inter-compressor housing, and an outlet section of said downstream portion of the air evacuation passage being defined as the minimum section between the outer edge of said downstream surface of the VBV gate and said downstream end surface of the inter-compressor housing, a ratio between said outlet and inlet sections is between 1 and 5

[0030] In preferred embodiments of the invention, in any cross-section plane orthogonal to the door axis and passing through the external surface of the VBV door in the fully open position, said external surface is shaped so that a line, tangent to said external surface at the level of the downstream edge thereof, intercepts the evacuation grid: • upstream of a downstream end of the drainage grate; • downstream of an upstream end of the drainage grate; and • downstream of an intersection between the drainage grid and a radial line passing through the downstream edge of said external surface.

[0031] In preferred embodiments of the invention, the inter-compressor assembly is configured so that to move from the closed position to the fully open position, the VBV gate pivots through an angle between 5 degrees and 45 degrees.

[0032] In preferred embodiments of the invention, the inter-compressor assembly is configured so that in the fully open position, the upstream edge of the internal surface is separated from the upstream edge of the orifice considered by a distance of between 2% and 55% of a radial extent of an inlet of the internal annular vein section.

[0033] In preferred embodiments of the invention, said external surface of the VBV gate is in the form of a ramp with an axially concave cross-section from the upstream edge of said external surface to the downstream edge of said external surface.

[0034] In preferred embodiments of the invention, the inter-compressor assembly comprises a support and actuation device including: • a guide frame rigidly attached to the inter-compressor housing, arranged radially outwards from the VBV gate, and shaped to define a circular arc-shaped path extending transversely to the gate axis of the VBV gate, with its center of curvature located on said gate axis; and • a U-shaped carriage frame having a base and two legs connected to each other by the base, the two legs being rigidly connected respectively to two opposite circumferential ends of the VBV door, the base being movably mounted on the guide frame so as to be guided along said path, and the base comprising a hinge structure intended to be connected to a synchronized actuation system of the VBV doors so that the latter controls a movement of the base along said path resulting in a pivoting of the VBV door around the door axis.

[0035] In other preferred embodiments of the invention, the inter-compressor assembly comprises a support and actuation device including: • two support rods rigidly attached to the inter-compressor housing, arranged circumferentially on either side of the VBV gate, and having respective first ends on which are respectively articulated two opposite circumferential ends of the VBV gate, along an axis defining the gate axis, and respective second ends opposite to said first ends; • a movable frame arranged radially outwards from the VBV door, circumferentially between the two support rods, articulated on the respective second ends of the two support rods along a frame axis parallel to the door axis, and comprising a hinge structure intended to be connected to a synchronized VBV door actuation system such that the latter controls a pivoting of the movable frame around the frame axis; and • two actuating rods arranged circumferentially on either side of the VBV door and the moving frame, and having first respective ends articulated respectively on the two circumferential ends of the VBV door and second respective opposite ends articulated on the moving frame, so that each of the support rods forms, together with the VBV door, the moving frame, and with one of the corresponding actuating rods, a deformable parallelogram controlling and guiding the pivoting of the VBV door around the door axis under the effect of a pivoting of the moving frame around the frame axis.

[0036] The invention also relates to a turbomachine, comprising at least two compressors separated from each other by an inter-compressor assembly of the type described above. Brief description of the drawings

[0037] 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:

[0038] [Fig-1] is a schematic axial cross-sectional view of a turbomachine;

[0039] [Fig.2] is a schematic perspective view of an inter-compressor housing of the turbomachine of the [Fig.1], shown in isolation;

[0040] [Fig.3] is a partial schematic half-view in axial section and larger scale of the turbomachine of [Fig.1], illustrating a part of the casing of [Fig.2] with a VBV gate in the closed position;

[0041] [Fig.3A] is a larger scale view of the VBV gate shown in isolation;

[0042] [Fig.4] is a view similar to [Fig.3], showing the VBV gate in the position of full opening;

[0043] [Fig.5] is a schematic perspective view of the VBV door and a support and guidance device for the latter, according to a first preferred embodiment, illustrating the VBV door in the closed position;

[0044] [Fig.6] is a view similar to [Fig.5], showing the VBV door in the fully open position;

[0045] [Fig.7] is a schematic perspective view of the VBV door and a support and guidance device for the latter, according to a second preferred embodiment, illustrating the VBV door in the closed position;

[0046] [Fig-8] is a view similar to [Fig.7], showing the VBV door in the fully open position.

[0047] Throughout these figures, identical references may designate identical or analogous elements. Detailed presentation of preferred embodiments

[0048] 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, and a secondary flow F3 circulating in a secondary flow channel, hereinafter referred to as the secondary flow SV, arranged around the primary flow PV.

[0049] By way of illustration, 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, which together define the primary flow PV. The respective rotors of the high-pressure compressor and the high-pressure turbine are connected by a shaft called the "high-pressure shaft," while the respective rotors of the low-pressure compressor and the low-pressure turbine are connected by a shaft called the "low-pressure shaft," in a well-known manner. These rotors are mounted to rotate about an axis 28 of the turbomachine.

[0050] 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 passes 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 D of the gas flow in the primary PV and secondary SV sections of the turbomachine, along the axial direction X.

[0051] The turbomachine includes in particular an inter-compressor housing 40 arranged axially between the low-pressure compressor 14 and the high-pressure compressor 16, and shown in isolation in [Fig. 2]. In the non-limiting context of a twin-spool turbojet engine, such an inter-compressor housing 40 is sometimes referred to as an inter- median.

[0052] The inter-compressor housing 40 comprises, for example, an outer annular housing wall 42, a hub 44, guide vanes 46 extending from the outer annular housing wall 42 to the hub 44, and structural arms 48 and 50 radially connecting the outer annular housing wall 42 to the hub 44. The outer annular housing wall 42 extends around a section or segment of the secondary flow SV, while the hub 44 extends radially inside the section of the secondary flow SV, and radially outside with respect to a section or segment of the primary flow PV.

[0053] The hub 44 includes an external annular hub wall 52 which internally delimits the section of the secondary vein SV, an intermediate annular hub wall, referred to simply as the first ferrule 54 in the following, which externally delimits the section of the primary vein PV, an internal annular hub wall 55 which internally delimits the section of the primary vein PV, and other arms 56 connecting the first ferrule 54 to the internal annular hub wall 55. For convenience, the external annular hub wall 52 is referred to as the second ferrule 52 in the following.

[0054] The hub 44 further comprises, for example, an upstream transverse wall 57 and a downstream transverse wall 58 which each connect the first ferrule 54 to the second ferrule 52 and respectively delimit an upstream side and a downstream side of an intervein cavity 59 defined between the first ferrule 54 and the second ferrule 52.

[0055] The various annular walls constituting the inter-compressor housing 40 are of course centered along an axis of this housing coinciding with the axis 28 of the turbomachine.

[0056] With reference to figures 3 and 4, the inter-compressor housing 40 is associated with an air discharge system, with which it constitutes an inter-compressor assembly according to the terminology adopted in this description.

[0057] This air discharge system comprises an annular row of orifices 60 formed in the first ferrule 54 (one of which is visible in section in the figures). Each orifice 60 is thus flush with the segment of the primary vein PV and opens into a corresponding air discharge passage 61 defined between the first ferrule 54 and the second ferrule 52 and generally oriented in the radial direction R. In the illustrated example, the air discharge passage 61 is defined by the inter-vein cavity 59. There may be a single air discharge passage 61 extending annularly around the axis 28 and thus common to all the orifices 60 or, alternatively, circumferential compartmentalization means for the inter-vein cavity 59 may define a plurality of air discharge passages 61, for example, each communicating with a corresponding orifice 60.The second ferrule 52 includes at least one drainage grid 63 through which the air drainage passage 61 or each . Air evacuation passage 61 opens into the section of the secondary vein SV. The grid 63 or each of the grids 63 is thus arranged radially opposite the annular row of orifices 60.

[0058] Furthermore, for each of these orifices 60, the air discharge system includes a corresponding VBV 62 door pivotally mounted about a corresponding door axis 64 on a part of the inter-compressor housing 40, so that said VBV 62 door is movable between a closed position, in which the VBV 62 door closes the orifice 60 ([Fig.3]), and a fully open position, in which the VBV 62 door allows air to flow through the orifice 60 ([Fig.4]).

[0059] For at least one of the orifices 60, and preferably for each of these orifices, the gate axis 64 of the corresponding VBV gate 62 is arranged between an upstream edge 66 of the orifice and a downstream edge 68 of the orifice, at respective distances from these upstream and downstream edges such that, in the fully open position ([Fig. 4]), the VBV gate 62 allows both the circulation of an upstream airflow 70A through an upstream portion 60A of the orifice defined upstream of the VBV gate 62 and the circulation of a downstream airflow 70B through a downstream portion 60B of the orifice defined downstream of the VBV gate. The VBV gate is thus a hybrid VBV gate, with a butterfly-type opening, as explained in the aforementioned applicant document FR3122903A1.

[0060] In particular, as explained in document FR3122903A1, an average distance between the gate axis 64 of the VBV gate 62 and the upstream edge 66 of the orifice 60 is advantageously between 0.2 and 0.8 times an average distance between the upstream edge 66 of the orifice and the downstream edge 68 of the orifice. By "average distance" is to be understood a distance measured in any plane containing the axis 28 and averaged in the circumferential direction C.

[0061] As will become clearer in what follows, depending on the type of support and actuation means which connect the VBV 62 door to the inter-compressor housing 40, the door axis 64 can be materialized by one or more parts (pin(s), rod(s), etc.) or be a virtual axis defined by a rotation kinematic imposed by said support and actuation means.

[0062] In addition, the gate axis 64 can intercept the VBV gate 62 (as in the illustrated example) or be offset from the VBV gate.

[0063] The upstream edges 66 and downstream edges 68 of the orifice are preferably defined by sealing gaskets 66A, 68A made of compressible material, for example elastomeric material.

[0064] The VBV 62 door has an external profile formed of an internal surface 72, an external surface 74, and a downstream surface 76 ([Fig.3A]).

[0065] The internal surface 72 delimits a radially internal side of the VBV gate so that that in the closed position ([Fig.3]), the internal surface 72 closes the considered orifice 60.

[0066] The internal surface 72 has an upstream edge 72A at its upstream end ([Fig. 3A]), and a downstream edge 72B at its downstream end. The internal surface 72 is advantageously shaped to reconstitute the first ferrule 54, that is, so that the internal surface 72 has substantially the shape that the first ferrule 54 would have in the same location if there were no orifice 60. In particular, the internal surface 72 is shaped to integrate with the first ferrule 54 without (or substantially without) aerodynamic discontinuity at the junctions between the internal surface 72 and the first ferrule 54.

[0067] The external surface 74 ([Fig.3A]) delimits a radially external side of the VBV gate and extends radially outwards in the direction D, from an upstream edge 74A of the external surface 74 contiguous to the upstream edge 72A of the internal surface 72, to a downstream edge 74B of the external surface 74.

[0068] In the open position ([Fig.4]), the external surface 74 thus delimits an upstream portion 61A of the air evacuation passage 61 defined upstream of the VBV door, and therefore extending radially outwards from the upstream portion 60A of the orifice 60.

[0069] In a manner known per se, the external surface 74 preferentially has a ramp shape with a concave axial section from its upstream edge 74A to its downstream edge 74B, so as to best guide air and any debris taken from the primary PV vein towards the evacuation grid 63.

[0070] The downstream surface 76 ([Fig.3A]) delimits a downstream side of the VBV gate and extends radially outwards from an internal edge 76A of this downstream surface 76 contiguous to the downstream edge 72B of the internal surface 72 to an external edge 76B of the downstream surface 76 contiguous to the downstream edge 74B of the external surface 74.

[0071] In the open position ([Fig.4]), the downstream surface 76 delimits a downstream portion 61B of the air evacuation passage 61 defined downstream of the VBV door, between the latter and a downstream end surface 78 of the inter-compressor housing, for example formed by the aforementioned downstream transverse wall 58, and having an internal edge 78A connected to the first ferrule 54 at the level of the downstream edge 68 of each orifice 60. The downstream end surface 78 of the inter-compressor housing thus delimits a downstream side of the downstream portion 61B of the air evacuation passage 61.

[0072] According to a particular feature of the invention, the downstream surface 76 has a convex axial cross-section shape from its inner edge 76A to its outer edge 76B.

[0073] Furthermore, an angle 0, defined between the tangent T1 to the downstream surface 76 at the level of the internal edge 76A of the latter and the tangent T2 to the internal surface 72 at the level of the downstream edge 72B of the latter, is between 120 and 140 degrees, and preferably 130 degrees, approximately equal to or nearly equal to 130 degrees. It should therefore be understood that angle 0 is defined at the junction between the internal surface 72 and downstream surface 76.

[0074] Such a convex shape and angle help to limit the risk of flow separation along the internal surface 72 and then the downstream surface 76 after passing through the downstream portion 60B of the orifice 60. The invention thus limits the risk that a portion of the primary flow F2, having been aerodically disturbed by the VBV gate 62 in the open position, may reach the inlet 79 of the high-pressure compressor (Figures 2 and 3) and thus disrupt the operation of this compressor, instead of being drawn into the downstream portion 61B of the air discharge passage downstream of the VBV gate. The invention also limits the risk that a portion of the airflow, previously extracted from the primary flow PV by the upstream portion 61A of the air discharge passage, may return to the primary flow by passing through the downstream portion 61B of this passage.

[0075] The shape of the downstream end surface 78 of the inter-compressor housing is preferably also optimized to limit such risks of flow return through the downstream portion 61B of the air exhaust passage.

[0076] To this end, the downstream end surface 78 has a concave axial cross-section, for example in the form of a ramp curved radially outwards. More particularly, the downstream end surface 78 is shaped so that, viewed in axial section, the downstream portion 61B of the air exhaust passage 61 has a flared shape up to the outer edge 76B of the downstream surface 76, when the VBV door is in the fully open position ([Fig.4]).

[0077] Furthermore, to optimize the guidance of both the upstream airflow 70A and the downstream airflow 70B towards the exhaust grille 63, the external surface 74 of the VBV door 62 is shaped such that, in any cross-sectional plane orthogonal to the door axis 64 and passing through the external surface 74 of the VBV door in the fully open position ([Fig. 4]), a line TL, tangent to the external surface 74 at its downstream edge 74B, intersects the exhaust grille 63 at a point ITL located upstream of a downstream end 63B of the exhaust grille 63, and downstream of an upstream end 63A of the exhaust grille 63, and, in particular, downstream of an intersection point IRL between the exhaust grille 63 and a radial line RL passing through the downstream edge 74B of the external surface 74.Preferably, the intersection point IRL between the drainage grid 63 and the radial line RL is itself located downstream of the upstream end 63A of the drainage grid 63.

[0078] To further optimize the guidance of airflow through the VBV 62 door towards the exhaust grille 63, with reference to [Fig. 4], a radial extent L1 of the VBV 62 door in the fully open position (defined between the inner and outer edges of the downstream surface 76) is preferably greater than half a distance radial L2 separating the inner edge of the downstream surface 76 and the downstream end 63B of the grid.

[0079] Furthermore, considering with reference to [Fig.4] an inlet section SI of the downstream portion 61B of the air evacuation passage 61, defined as the minimum section between the inner edge 76A of the downstream surface 76 of the VBV door and the downstream end surface 78 of the inter-compressor housing, and an outlet section S2 of the downstream portion 61B of the air evacuation passage 61, defined as the minimum section between the outer edge 76B of the downstream surface 76 of the VBV door and the downstream end surface 78 of the inter-compressor housing, a ratio S2 / S1 between said outlet and inlet sections is preferably between 1 and 5.

[0080] The air discharge system is further advantageously configured so that to move from the closed position to the fully open position, the VBV door pivots through an angle between 5 degrees and 45 degrees.

[0081] In preferred embodiments, the upstream edge 72A of the internal surface 72 is separated from the upstream edge 66 of the considered orifice 60 by a distance between 2% and 55% of a radial extent RE of the inlet of the section or segment of the primary vein PV delimited by the inter-compressor housing ([Fig.2]).

[0082] Furthermore, the VBV door advantageously includes cheeks, not visible in Figures 3 and 4 but visible in Figures 5 to 8 where these cheeks are designated by the numerical reference 80. These cheeks 80 extend respectively to the two opposite circumferential ends of the VBV door, projecting radially outwards and upstream relative to the external surface 74 of the door, so as to circumferentially delimit the upstream portion 61A of the air evacuation passage 61.

[0083] Figures 5 and 6 illustrate a support and actuation device 90, according to a first embodiment, intended to support the VBV 62 door and to control the pivoting of the latter around the door axis 64.

[0084] This device 90 comprises a guide frame 92 and a trolley frame 94.

[0085] Generally, the guide frame 92 is rigidly attached to the inter-compressor housing 40 (not visible in Figures 5 and 6), and is arranged at a distance radially outwards with respect to the VBV door 62. The guide frame 92 is shaped to define a path 93 in the form of an arc of a circle extending transversely to an axis and whose center of curvature is located on said axis, the latter defining the axis of the door 64.

[0086] Furthermore, the carriage frame 94 is generally U-shaped and thus has a base 96 and two legs 98A, 98B connected to each other by the base 96. The two legs 98A, 98B are rigidly connected respectively to two opposing circumferential ends 62C, 62D of the VBV gate 62. The base 96 is movably mounted on the guide frame 92 so as to be guided along the path 93. Moreover, the base 96 includes a hinge structure 100 intended to be connected to a synchronized actuation system for the VBV doors so that this synchronized actuation system controls a movement of the base 96 along said path resulting in a pivoting of the VBV door 62 around the door axis 64. The synchronized actuation system, which will not be described here (and is not visible in the figures), can for example be a system of the type described in document FR3119421A1.

[0087] More specifically, the guide frame 92 preferably comprises two lateral structures 102A, 102B connected to each other, at their upstream and downstream ends, respectively by two beams 104 extending in the circumferential direction C. The two lateral structures 102A, 102B each define a corresponding light 106 having the aforementioned arc shape and thus defining the aforementioned path.

[0088] The frame-carriage 94 preferably comprises two lateral structures, each in the form of a perforated plate to minimize the mass of the device, and having respective radially internal portions fixed to the opposite circumferential ends 62C, 62D of the VBV door 62 and constituting respectively the aforementioned legs 98A, 98B. The base 96 is, for example, formed by a radially external end of each of these two lateral structures and by a beam 108 rigidly connecting them.

[0089] The articulation structure 100 is for example formed of an ear designed to articulate with a control rod belonging to the aforementioned synchronized actuation system.

[0090] The guidance of the base 96 by the guide frame 92 is preferably ensured by rollers 110 carried by the base 96 and engaged in each of the slots 106, with at least two rollers 110 per slot 106 so as to block one degree of freedom for the carriage frame and thus force the latter, and therefore also the VBV door 62, to pivot around the door axis 64 when the rollers move along the slots 106 (only the two rollers 110 located on the circumferential side shown in the foreground in Figures 5 and 6 are visible in these figures). The movement of the rollers 110 along the slots 106 can be achieved by sliding or by means of bearings provided for this purpose.

[0091] One advantage of such a support and actuation device lies in the fact that it extends around the upstream portion 61A of the air exhaust passage 61 without directly obstructing the flow in front of and near the external surface 74 of the VBV door. Another advantage lies in the fact that the device is sufficient to define the axis of the door 64, without requiring any other structural means for this purpose, for example, means fixed to the first ferrule 54. In the illustrated example, two auxiliary pins 112 are nevertheless arranged on the axis of the door 64 so as to take up the aerodynamic forces suffered by the VBV door 62 and reduce the forces applied to the guide frame 92. These auxiliary pins 112 can be fixed to the VBV door and articulated to means fixed to the first ferrule 54, or vice versa.

[0092] Figures 7 and 8 illustrate a support and actuation device 120 intended to support the VBV 62 door and to control the pivoting of the latter around the door axis 64, according to a second embodiment.

[0093] This device 120 comprises two support rods 122, a movable frame 124, and two actuating rods 126 (only one support rod 122 and one actuating rod 126, located on the circumferential side shown in the foreground of figures 7 and 8, being visible on the latter).

[0094] Generally, the two support rods 122 are rigidly attached to the inter-compressor housing 40 by means that may be conventional and which will not be described here (and are not visible in the figures). These two support rods 122 are arranged circumferentially on either side of the VBV door 62, and have respective first ends 122A on which are respectively articulated the two opposite circumferential ends 62C, 62D of the VBV door 62, along an axis defining the door axis 64, and respective second ends 122B opposite to the first ends 122A.

[0095] Furthermore, the movable frame 124 is radially offset outwards relative to the VBV door 62 and is located circumferentially between the two support rods 122. The movable frame 124 is articulated on the respective second ends 122B of the two support rods 122, along a frame axis 128 parallel to the door axis 64. Analogously to the example in Figures 5 and 6, the movable frame 124 includes a hinge structure 100 intended to be connected to a synchronized actuating system for the VBV doors, which is, for example, again of the type described in document FR3119421A1, such that this synchronized actuating system controls a pivoting of the movable frame 124 about the frame axis 128. Here again, the hinge structure 100 is, for example, made up of a lug designed to articulate with a rod control belonging to the aforementioned synchronized actuation system.

[0096] Finally, the two actuating rods 126 are arranged circumferentially on either side of the VBV gate 62 and the movable frame 124, each axially and radially opposite a corresponding support rod 122. The two actuating rods 126 have respective first ends 126A which are respectively articulated on the two circumferential ends 62C, 62D of the VBV gate 62, and respective opposing second ends 126B which are articulated on the movable frame 124, so that each of the support rods 122 forms, together with the VBV door 62, the movable frame 124, and with one of the corresponding actuating rods 126 (i.e. the actuating rod 126 located on the same circumferential side as the support rod 122 considered), a deformable parallelogram controlling and guiding the pivoting of the VBV door 62 around the door axis 64 under the effect of a pivoting of the movable frame 124 around the frame axis 128.

[0097] Thus, an actuation of the articulation structure 100 by the synchronized actuation system of the VBV doors results in a pivoting of the mobile frame 124 around the frame axis 128, which pivoting is passed on to the VBV door 62, via the two actuating rods 126, in the form of a pivoting of the VBV door 62 around the door axis 64 defined by the support rods 122.

[0098] The mobile frame is for example made up of two lateral beams 124A, 124B and a transverse beam (masked in the figures) connecting the lateral beams 124A, 124B to each other and supporting the articulation structure 100.

[0099] An advantage of such a support and actuation device lies here again in the fact that it extends around the upstream portion 61A of the air exhaust passage 61 without directly obstructing the flow opposite and near the external surface 74 of the VBV door. Another advantage lies in the fact that the device is sufficient to define the axis of the door 64, without requiring any other structural means for this purpose, for example, means fixed to the first ferrule 54.

[0100] The invention finds a particularly advantageous application in small-sized motors, which offer an inter-vein space having a particularly limited radial extent.

Claims

1. Demands Inter-compressor assembly for turbomachinery, comprising: • an inter-compressor casing (40) comprising: a first ferrule (54) extending annularly around an axis (28) of the inter-compressor casing and externally delimiting a section of internal annular flow (PV) intended for the flow of a primary air stream (F2) between two compressors (14, 16) of a turbomachine in a direction (D) going from an upstream side of the inter-compressor casing to a downstream side thereof; a second ferrule (52) extending annularly around the first ferrule (54) so ​​as to internally delimit a section of external annular flow (SV) intended for the flow of a bypass air stream in said direction (D); • an air discharge system comprising an annular row of orifices (60) formed in said first ferrule (54) to connect the internal annular vein section (PV) with at least one radial air discharge passage (61) opening into the external annular vein section (SV) through at least one discharge grid (63) arranged radially opposite the annular row of orifices (60), and, for each of said orifices (60), a corresponding VBV gate (62) mounted on a part of the inter-compressor housing (40) so as to be movable, by pivoting about a gate axis (64), between a closed position, in which an internal surface (72) of the VBV gate closes the orifice (60), and a fully open position, in which the VBV gate allows air to flow through the orifice (60); in which the VBV (62) door has an external profile formed by: • said internal surface (72), which extends from an upstream edge (72A) to a downstream edge (72B) thereof; • an external surface (74) that delimits a radially external side of the VBV gate and extends radially outwards in said direction (D), from an upstream edge (74A) of said external surface (74) contiguous to the upstream edge (72A) of

2. said internal surface (72), up to a downstream edge (74B) of said external surface (74); • a downstream surface (76) which delimits a downstream side of the VBV gate and extends radially outwards from an internal edge (76A) of said downstream surface (76) contiguous to the downstream edge (72B) of said internal surface (72) to an external edge (76B) of said downstream surface (76) contiguous to the downstream edge (74B) of said external surface (74), said downstream surface (76) having a convex axial cross-section shape from the internal edge (76A) thereof to the external edge (76B) thereof; in which an angle (0) defined between a tangent (T1) to the downstream surface (76) at the level of the inner edge (76A) of the latter and a tangent (T2) to the inner surface (72) at the level of the downstream edge (72B) of the latter is between 120 and 140 degrees; and in which the gate axis (64) of the corresponding VBV gate is arranged axially between an upstream edge (66) of the orifice and a downstream edge (68) of the orifice at a distance from said upstream and downstream edges such that, in the fully open position, an upstream end portion of the VBV gate protrudes into the internal annular vein section (PV) while a downstream end portion of the VBV gate protrudes into the air discharge passage (61), so that the VBV gate (62) allows air to flow radially outwards towards the grid (63) both through an upstream portion (61 A) of the air discharge passage (61) defined upstream of the external surface (74) of the VBV gate,and through a downstream portion (61B) of the air evacuation passage (61) defined between the downstream surface (76) of the VBV door and a downstream end surface (78) of the inter-compressor housing having an internal edge (78A) connected to the first ferrule (54) at the level of the downstream edge (68) of each orifice (60) and delimiting a downstream side of the air evacuation passage (61). Inter-compressor assembly according to claim 1, wherein said downstream end surface (78) has a concave axial section and is shaped so that, viewed in axial section, said downstream portion (61B) of the air discharge passage (61) has a flared shape up to the outer edge (76B) of said downstream surface (76) when the VBV door is in the fully open position.

3. Inter-compressor assembly according to claim 1 or 2, wherein, an inlet section (S1) of said downstream portion (61B) of the air discharge passage (61) being defined as the minimum section between the inner edge (76A) of said downstream surface (76) of the VBV gate and said downstream end surface (78) of the inter-compressor housing, and an outlet section (S2) of said downstream portion (61B) of the air discharge passage (61) being defined as the minimum section between the outer edge (76B) of said downstream surface (76) of the VBV gate and said downstream end surface (78) of the inter-compressor housing, a ratio S2 / S1 between said outlet and inlet sections is between 1 and 5.

4. An inter-compressor assembly according to any one of claims 1 to 3, wherein, in any cross-sectional plane orthogonal to the gate axis (64) and passing through the external surface (74) of the VBV gate in the fully open position, said external surface (74) is shaped such that a line (TL), tangent to said external surface (74) at the level of the downstream edge (74B) thereof, intercepts the discharge grid (63): • upstream of a downstream end (63B) of the discharge grid (63); • downstream of an upstream end (63A) of the discharge grid (63); and • downstream of an intersection between the discharge grid (63) and a radial line passing through the downstream edge (74B) of said external surface (74).

5. Inter-compressor assembly according to any one of claims 1 to 4, wherein, to move from the closed position to the fully open position, the VBV door pivots through an angle between 5 degrees and 45 degrees.

6. Inter-compressor assembly according to any one of claims 1 to 5, wherein, in the fully open position, the upstream edge (72A) of the internal surface (72) is separated from the upstream edge (66) of the orifice (60) considered by a distance between 2% and 55% of a radial extent (RE) of an inlet of the internal annular vein section (PV).

7. Inter-compressor assembly according to any one of claims 1 to 6, wherein said external surface (74) of the VBV gate (62) is in ramp shape with concave axial section from the upstream edge (74A) of said external surface (74) to the downstream edge (74B) of said external surface (74).

8.

9. Inter-compressor assembly according to any one of the claims 1 to 7, including a support and actuation device (90) comprising: a guide frame (92) rigidly attached to the intercompressor housing (40), arranged at a distance radially outwards with respect to the VBV gate (62), and shaped to define a path (93) in the form of an arc of a circle extending transversely to the gate axis (64) of the VBV gate and whose center of curvature is located on said gate axis (64);and a U-shaped carriage frame (94) having a base (96) and two legs (98A, 98B) connected to each other by the base, the two legs being rigidly connected respectively to two opposite circumferential ends (62C, 62D) of the VBV gate (62), the base being movably mounted on the guide frame (92) so as to be guided along said path (93), and the base (96) comprising a hinge structure (100) intended to be connected to a synchronized actuation system for the VBV gates so that the latter controls a movement of the base (96) along said path (93) resulting in a pivoting of the VBV gate (62) around the gate axis (64). Inter-compressor assembly according to any one of the claims 1 to 7, including a support and actuation device (120) comprising: two support rods (122) rigidly attached to the inter-compressor housing (40), arranged circumferentially on either side of the VBV door (62), and having respective first ends (122A) on which are respectively articulated two opposite circumferential ends (62C, 62D) of the VBV door (62), along an axis defining the door axis (64), and respective second ends (122B) opposite to said first ends (122A); a movable frame (124) arranged at a radial distance towards the exterior relative to the VBV door (62), circumferentially between the two support rods (122), articulated on the respective second ends (122B) of the two support rods (122) along a frame axis (128) parallel to the door axis (64), and comprising a hinge structure (100) intended to be connected to a synchronized VBV door actuation system such that the latter controls a pivoting of the movable frame (124) around the frame axis (128); and two actuating rods (126) arranged circumferentially on either side of the VBV door (62) and the movable frame, and having respective first ends (126A) articulated respectively on the two circumferential ends (62C, 62D) of the VBV door (62) and respective second ends (126B) articulated on the movable frame (124), so that each of the support rods (122) forms, together with the VBV door (62), the movable frame (124), and with one of the corresponding actuating rods (126), a deformable parallelogram controlling and guiding the pivoting of the VBV door (62) around the door axis (64) under the effect of a pivoting of the movable frame (124) around the frame axis (128).

10. Turbomachine, comprising at least two compressors (14, 16) separated from each other by an inter-compressor assembly according to any one of claims 1 to 9.

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