Pitch-setting device for a variable stator vane

Abstract

The invention relates to a device for setting the pitch of a vane (1) for a turbomachine, the device comprising: - a vane that is pivotable in a first direction and comprises a leading edge, a trailing edge and a base (6) which has an opening (7); - a fin (3) that comprises a leading edge, a trailing edge and a portion (12) accommodated in the opening; - a control means that rotates the vane (4) and moves the portion of the fin; - so as to keep a variation in a C / D ratio below 10%, the ratio being between a projection in a direction of projection normal to the first direction of a: - length C between the leading edge and the leading edge of the fin (3); and - length D between the leading edge and the trailing edge of the vane.

Description

DESCRIPTION TITLE: TIMING DEVICE FOR VARIABLE TIMING STATOR VANE TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of aeronautics and particularly to the field of variable-pitch blades for aircraft turbomachines.

[0002] A first aspect of the invention relates to a timing device for a variable-pitch stator blade. A second aspect of the invention relates to a rectifier stage comprising the timing mechanism according to the first aspect of the invention. A third aspect of the invention relates to an aircraft compressor comprising a rectifier stage according to the second aspect of the invention. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] An aeronautical turbomachine typically consists of a compressor, a combustion chamber, and a turbine. The role of the turbine is to drive the compressor by extracting some of the pressure energy from the hot gases leaving the combustion chamber and transforming it into mechanical energy.

[0004] An axial compressor consists of a rotating part, the rotor, a fixed part, the stator, and a casing, the casing, the stator and the casing being integral with each other. The rotor comprises a drum consisting of an assembly of several discs on which are fixed moving blades in a circumferential row. The stator consists of a plurality of blades fixed on the casing or on shrouds in a circumferential row called fixed blades (because they do not rotate around the axis of rotation but can be mobile in rotation along their own axis). Each row of fixed blades of the stator, called rectifiers, constitutes a rectifier. A row of moving blades and a row of fixed blades form a compressor stage.

[0005] In a compressor, to optimize the efficiency of the turbomachine and the pumping margin according to the speed, one or more rows of straightening blades can have a variable pitch angle, that is to say that the angle of attack of these blades varies according to the flight conditions. A stage of This type comprises an annular row of variable-pitch stator vanes (also called VSV - acronym for Variable Stator Vanes) which are carried by the external annular casing, generally of a compressor of the turbomachine. The angular pitch of the stator vanes in a turbomachine is intended to adapt the geometry of the compressor to its operating point and in particular to optimize the efficiency and the pumping margin of this turbomachine and to reduce its fuel consumption in the different flight configurations.

[0006] Each of these blades is movable in rotation about its axis between a first “open” or “fully open” position in which each blade extends substantially parallel to the longitudinal axis of the turbomachine, and a second “closed” or “quasi-closed” position in which the blades are inclined relative to the axis of the turbomachine and thus reduce the air passage section through the blade stage.

[0007] One technique for improving the efficiency of turbomachinery includes the use of vanes to reduce secondary airflows. For example, such secondary airflows may take the form of vortices at the connection between a blade and its plate. An example of the use of this technique in the presence of variable-pitch vanes is illustrated in [fig. 1] and described in patent application WO 2021 / 069817 A1 filed by the applicant.

[0008] [Fig. 1] illustrates a blade 114 comprising a vane 112 extending radially from a plate 116 along the main axis of the blade 114. The blade 114 has variable pitch and can pivot about its main axis. As can be seen, during operation of the turbomachine, the circulation of air in the flow produces disturbances 132 at the connection between the blade 112 and the plate 116.

[0009] The disturbances 132 take the form of vortices which amplify according to the direction of flow, from upstream to downstream, becoming more significant as one approaches the trailing edge 126 of the blade 112. The use of a fin 134 extending radially makes it possible to limit the expansion of the disturbances 135 towards the downstream 136.

[0010] However, in the known solution illustrated in [fig. 1] the vanes are integrated directly into the plate 116 of the variable-pitch vane. It follows that when the pitch of the stator vane varies, the axial position of the vane 134 also varies. In particular, the vane 134 passes upstream of the leading edge of the vane blade 112 for large pitches, which makes the vane 134 ineffective.

[0011] There is currently no known technical solution for producing a variable pitch stator blade with vanes that can improve airflow for all stator blade pitches. SUMMARY OF THE INVENTION

[0012] The invention provides a solution to the problems mentioned above by proposing a device for setting a variable-pitch stator blade that allows both the orientation and position of a vane to be varied. In particular, the invention allows the position and orientation of the vanes to be adapted to the setting position of the blade, while optimizing the airflow to reduce the formation of vortices near the base of the blade.

[0013] A first aspect of the invention relates to a device for setting a variable-pitch stator blade for an aircraft turbomachine, said setting device comprising: - a pivoting stator blade comprising: • a stator blade base and • a blade extending in a first direction between the base and a tip, said blade being delimited in a second direction by a leading edge and a trailing edge; - a blade pivot shaft integral in rotation with the blade, having an axis of rotation extending in the first direction and - a fin extending in a direction parallel to the first direction and being delimited in a third direction by a fin leading edge and a fin trailing edge; - the wedging device being characterized in that it comprises: • a light located in the stator blade base: • a portion of the fin comprising a part housed in the light; - a control means rotating the blade pivot shaft between a first angular position and a second angular position and moving the portion of the blade between a first position corresponding to the first angular position and a second position corresponding to the second angular position; - so that a variation of a ratio between a length C and a length D is less than 10%, D being the projection of the distance between the leading edge of the blade and the leading edge of the winglet in a projection direction (X) normal to the first direction, C being the projection in the projection direction (X) of the distance between the leading edge of the blade and the trailing edge of the blade.

[0014] The variation of the C / D ratio is understood to mean the variation of said ratio between the first angular position and the second angular position. This variation is calculated as the difference between the value of the C / D ratio in the first angular position and the value of the C / D ratio in the second angular position, the difference then being normalized by the value of the C / D ratio in the first or second angular position.

[0015] Indeed, by keeping the ratio between C and D by a projection according to a projection direction normal to the first direction, the winglet keeps its orientation relative to the leading edge of the blade, making it possible to optimize its role in reducing secondary air flows regardless of the orientation of the blade. The projection direction is, for example, the direction of air flow in the aircraft turbomachine.

[0016] The timing device according to the first aspect of the invention applies for example to a grid of stators with variable timings between which fins are positioned, the fins being attached to the hub or to the casing.

[0017] The fins help limit flow and improve flow near the hub or casing. This limits stalls on the blades and improves stator operability.

[0018] The observation is that it is difficult to integrate vanes on a variable pitch stator ring taking into account the aerodynamic specifications. These stators comprising the stator ring and the vanes with these variable pitch vanes are used in many axial compressors to pre-direct the flow in the first stages of the compressor.

[0019] The timing device according to the first aspect of the invention provides a means of integrating fins to match the timing of the stator grid. The system directly follows the timing of the stator while maintaining the main positioning and orientation parameters necessary to have efficient fins in any stator blade timing position.

[0020] Angular position means a position of the blade pivot shaft corresponding to a given pitch of the variable-pitch stator blade. For example, the first position may be a "fully open" position in which the blade is substantially parallel to the direction of air flow in the turbomachine and the second position may be a "fully closed" position in which the blade is inclined relative to the direction of air flow in the turbomachine so as to reduce the air passage section.

[0021] The projection direction is understood to mean a direction normal to the radial direction in which the stator blade extends. For example, the projection direction is the direction of air flow in a rectifier stage comprising a timing mechanism according to the first aspect of the invention.

[0022] In addition, the timing device according to the invention makes it possible to modify the relative position of the fin and the blade to keep the C / D ratio constant at each timing of the stator blade and to optimize the air flow near the base of the stator blade. This is possible thanks to the portion of the fin housed in the light of the blade base which guides the sliding of the slide connection. With each rotation of the control ring to modify the timing of the stator blade, the edges of the light guide the fin in translation which therefore modifies its position thanks to the sliding of the slide connection.

[0023] The timing device according to the first aspect of the invention therefore makes it possible to fix the relative orientation of the fin and the blade but also to fix the C / D ratio. These two conditions make it possible to optimize the air flow for any timing of the stator blade between the fully open and fully closed position.

[0024] In other words, the timing system according to the first aspect of the invention fixes the relative position of the grid fronts between the fin and the stator grid.

[0025] Additionally, the leading edge angle of the blade relative to the leading edge angle of the stator blade is maintained.

[0026] By using the wedging device according to the first aspect of the invention, the leading edge of the fin does not pass upstream of the leading edge of the stator, unlike patent WO202169817 A1.

[0027] The fins integrated using the system according to the first aspect of the invention thus improve the performance of the variable-pitch stators and increase the operability of these stator grids. The result is a compressor with an extended and more efficient operability range.

[0028] Advantageously, the wedging device comprises: • a blade pivot shaft extending radially in a direction parallel to the first direction and having an axis of rotation parallel to the axis of rotation of the blade pivot shaft; • a sliding connection connecting the fin pivot shaft and the fin; - said fin pivot shaft being rotationally integral with the slide connection, the slide connection allowing the fin portion to slide in the slot during rotation of the fin pivot shaft.

[0029] The blade pivot shaft is rotationally secured to an element of the slide connection, the slide connection thus comprises another element which can slide relative to the element secured to the blade pivot shaft and which is guided by the portion of blade housed in the light, so as to keep the ratio between the length C and the length D constant, independent of the angular position of the control ring and the blade pivot shaft, in order to improve the air flow.

[0030] According to one embodiment, the control means comprises a control ring having an angular position, said control ring rotating the blade pivot shaft and the vane pivot shaft. Due to the fact that the control ring rotates both the blade pivot shaft and the vane pivot shaft, the relative orientation of the stator vane and the vane is fixed. This makes it possible to choose a relative angle between the vane and the blade which allows to minimize the formation of vortices and to keep this relative angle constant for all the blade settings.

[0031] According to another embodiment, the control means comprises a second control ring connected to the vane pivot shaft.

[0032] Advantageously, the sliding connection includes: • A connecting element integral in rotation with the fin pivot shaft and extending from the fin pivot shaft; • A branch attached to the fin portion and capable of sliding inside the connecting element.

[0033] The connecting element allows the slide connection to slide relative to the fin pivot shaft while rotationally securing the slide and the fin pivot shaft.

[0034] Advantageously, the sliding connection extends in a direction normal to the axis of rotation of the fin pivot shaft. This arrangement makes it possible to modify the position of the fin without modifying its radial position.

[0035] Advantageously, the fin portion housed in the lumen extends from the sliding connection to a fin body in a direction parallel to the axis of rotation of the fin pivot shaft. This arrangement makes it possible to modify the position of the fin without modifying its radial position.

[0036] Advantageously, the axis of rotation of the vane pivot shaft is offset from the axis of rotation of the blade pivot shaft. This arrangement allows the relative position of the vane and stator vane to be changed to maintain the C / D ratio constant.

[0037] Advantageously, the light has a curved shape, for example in an arc of a circle.

[0038] Advantageously, the timing device according to the first aspect of the invention may comprise a plurality of variable-pitch stator vanes, a plurality of blades, a plurality of blade pivot shafts and a plurality of blade pivot shafts, the control means rotating the plurality of stator pivot shafts. This arrangement makes it possible to obtain a stator ring with a plurality of blades in which the same control ring modifies the timing of all the blades and all the blades associated with the blades, while preserving the geometric constraints on each blade / blade pair.

[0039] A second aspect of the invention relates to a rectifier stage comprising a stator ring and a timing device according to the first aspect of the invention, the timing device comprising a multiplicity of variable-pitch stator vanes, the variable-pitch stator vanes being distributed around the circumference of the stator ring, the projection direction being the direction of air flow in the rectifier stage.

[0040] Advantageously, the timing device according to the first aspect of the invention is positioned at the level of the casing or at the level of the hub of the rectifier stage according to the second aspect of the invention.

[0041] A third aspect of the invention relates to an aircraft turbomachine comprising a rectifier stage according to the second aspect of the invention.

[0042] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0043] Other advantages and characteristics of the invention will appear on reading the following description, illustrated by the figures in which:

[0044] [Fig. 1] illustrates a state-of-the-art variable-pitch stator blade;

[0045] [Fig. 2] schematically illustrates the connections of an embodiment of a stator blade timing device according to the first aspect of the invention relative to a stator ring;

[0046] [Fig. 3] illustrates a ratio of lengths of a blade and a vane of the blade setting device in two angular positions.

[0047] [Fig. 4a] illustrates a three-dimensional view of an example of a wedging device in a first position relative to a casing of a rectifier stage.

[0048] [Fig. 4b] illustrates the wedging device of Fig. 4a in a second position different from the first position.

[0049] [Fig. 5] illustrates a three-dimensional view of a section of a rectifier including an example of a wedging device. DETAILED DESCRIPTION

[0050] An exemplary embodiment of a device for setting a variable-pitch compressor or turbomachine blade according to the first aspect of The invention is described below. This example illustrates the characteristics and advantages of the invention.

[0051] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0052] For the understanding of the invention, the radial R, tangential T and axial A orientations will be adopted according to the RTA reference frame indicated in the figures, the tangent T and axial A axes of which extend in a horizontal plane according to the orientation in the figures. The axial axis A is parallel to an axis of rotation X of an aircraft turbomachine comprising the blade setting device according to the first aspect of the invention. The upstream of the leading edge of the variable-pitch blade towards the downstream of the variable-pitch blade is oriented along the axial axis of the RTA reference frame. In addition, the term longitudinal will be used for the direction extending along the periphery of a rectifier stage comprising the setting device according to the first aspect of the invention, by analogy with the terminology used in cylindrical coordinate reference systems.

[0053] In the description, the terms "upstream" and "downstream" are defined in relation to the direction of air flow from the air inlet into the turbomachine to the air outlet from the turbine.

[0054] [Fig. 1] has been described in relation to the state of the art.

[0055] [Fig. 2] illustrates an embodiment of a timing device 1 for a variable-pitch stator blade for an aircraft turbomachine.

[0056] The wedging device 1 according to the example of [fig. 2] comprises: • a variable-pitch stator blade comprising: o a stator blade blade 2 extending radially in a first direction and o a stator blade base 6 integral in rotation with the blade 2 and comprising a slot 7; • a blade pivot shaft 4 integral in rotation with the base 6, the blade pivot shaft 4 having a first axis of rotation parallel to the first direction. In this case the first axis of rotation is the same as the first direction (same axis).

[0057] The wedging device 1 according to the example illustrated in [fig. 2] further comprises: • a fin 3 comprising a fin body 13 and a fin portion 12 comprising a part housed in the light 7; • a fin pivot shaft 5 having an axis of rotation parallel to the first axis of rotation; • a sliding connection 9 connecting the fin pivot shaft 5 and the fin 3, the connection being integral in rotation with the fin pivot shaft 5, such that the rotation of the fin pivot shaft 5 slides the fin portion 12 in the slot 7 relative to the base 6; • a control ring 8 connected to the blade pivot shaft 4 and to the blade pivot shaft 5 so as to drive them simultaneously in rotation.

[0058] The blade pivot shaft 5 and the blade pivot shaft 4 are each intended to be mounted in a first and second bearing respectively, the two bearings have a recessed connection 14 as shown in FIG. 2. The two bearings are integrated in a stator ring which can be fixed to a casing or a hub of the turbomachine.

[0059] According to the embodiment illustrated in Figure 2, the sliding connection comprises a connecting element 11 receiving a branch 10, the branch 10 sliding in the connecting element 11.

[0060] In this embodiment, the sliding connection 9 is perpendicular to the axis of rotation of the fin pivot shaft 5, in other words the branch 10 extends in a direction normal to the axis of rotation of the fin pivot shaft 5 which allows it to slide in the connecting element 11.

[0061] The fin portion 12 housed in the slot 7 extends in a direction parallel to the axis of rotation of the fin pivot shaft 5, so as not to modify the radial position of the fin body 13 during a change in the timing of the blade.

[0062] According to an example of the wedging device 1 according to the first aspect of the invention, the base 6 of the stator blade may comprise a silicone skirt at the level of the light 7 housing the fin portion 12. This makes it possible to limit the interaction of the air with the light 7 and therefore to reduce aerodynamic losses.

[0063] Thus the variable pitch device allows the blade 3 to be integrated at the platform of a variable pitch stator blade and the integration method allows it to pivot while maintaining the relative angle with respect to screws of the stator grid while maintaining a constant relative axial position with respect to the stator grid.

[0064] In other words, the wedging device 1 is characterized by: - The blade pivot shaft 4 (also called the main shaft) under the base 6 with variable stator timing allowing the blade 2 to pivot. - The fin pivot shaft assembly 5 (also called secondary shaft) and the slide 9 attached to the fin 3 and to the fin pivot shaft 5, allowing simultaneous action on the angular orientation and the axial position of the fin.

[0065] The two rotation axes of the pivot shafts are fixed by means of a 14-type embedding connection.

[0066] The controls of the main or blade pivot shaft 4 and of the secondary or vane pivot shaft 5 are connected so as to respect the relative positioning constraints of the stator vane / vane, in angle and in axial position, illustrated by [Fig. 3].

[0067] [Fig. 3] shows two positions of the vane 3 relative to the blade 2 of the setting device 1 according to an example of the first aspect of the invention to show the simultaneous evolution of the setting of the stator vanes and the vanes. In particular, [Fig. 3] illustrates the position of the vane blades 2 and the vanes 3 for two possible stator vane settings, P1 and P2.

[0068] Each blade 2 is delimited in a projection direction X normal to the axis of rotation by a leading edge 21 and a trailing edge 22. The projection direction X is for example parallel to the axis of rotation of the turbomachine.

[0069] Similarly, each fin 3 is delimited by a fin leading edge 31 and a fin trailing edge 32.

[0070] According to one embodiment, the projection direction X is the direction of air flow in the turbomachine.

[0071] Whatever the position of the stator, the device 1 according to the first aspect of the invention makes it possible to maintain the ratio between the projection D along the projection direction X of the distance separating the leading edge of the stator blade 21 and the leading edge of the fin 31 and the projection C along the projection direction X of the stator chord. Whatever the pitch angle, D / C is maintained, namely D1 / C1 = D2 / C2.

[0072] The projection of the stator chord is equivalent to the projection of the distance d separating the leading edge 21 and the trailing edge 22.

[0073] The variable-pitch device also makes it possible to maintain the relative angle between the orientation of the skeleton at the leading edge of the stator and the orientation of the skeleton at the leading edge of the fin, namely A1 = A2.

[0074] As illustrated in the examples of Figures 4a, 4b and Figure 5, the device 1 is integrated into the variable-timing stator and is actuated by the same control ring as the stator timing. The fin pivot shaft 5, eccentric with respect to the axis of the fin, makes it possible to achieve the required amplitude of movement. The slide 9 makes it possible to correct the variation in distance between the fin 3 and its pivot shaft 5.

[0075] According to one embodiment, the timing device comprises a multiplicity of stator vanes and fins. The stator vanes and fins are distributed around a circumference to form a stator ring.

[0076] A second aspect of the invention relates to a rectifier stage comprising a stator ring and the wedging device 1 according to the first aspect of the invention. The stator ring comprises a plurality of openings each housing a base 6.

[0077] According to one embodiment, the stator ring is radially external to the blade 2 of the timing device. In this case the stator ring can be part of a casing or be fixed to the casing of the turbomachine.

[0078] According to another embodiment, the stator ring is radially internal to the timing device. In this case the stator ring may be part of a hub or be fixed to the hub of the turbomachine.

[0079] [Fig. 4a] and [Fig. 4b] illustrate an application of the wedging device 1 with a wide aperture 7 to accommodate a portion of the fin 3, so as to visualize the wedging device 1 more easily. In this case, the fin 3 is positioned at the hub. In other words, the stator ring is radially internal to the blade 2 of the wedging device and external to the slide connection and to the blade and blade pivot shafts 4 and 5 respectively. [Fig. 4a] shows a first wedging (first angular position) P1 of the stator blade 2 relative to the stator ring and a position of the fin 3 relative to the stator blade. [Fig. 4b] shows a second wedging P2 of the blade 2. The fin 3 can move forward or backward to maintain its relative position relative to blade 2 and maintains the same relative angle throughout the movement.

[0080] [Fig. 5] illustrates another embodiment of the wedging device 1 according to the first aspect of the invention. The wedging device is positioned on the casing this time. In other words, the stator ring is radially external with respect to the wedging device 1. In addition, as explained previously, the port 7 is thinner, to limit the effects of its aerodynamic interaction with the flow.

[0081] According to this embodiment illustrated in [Fig. 5] the section of the fin portion 12 is smaller than the section of the fin body 13. This makes it possible to reduce the width of the light 7 housing the fin portion 12 and therefore to limit the interaction of the air with the edges of the light 7.

[0082] According to a variant of the timing device 1, it is possible to vary the distance between the blade pivot shaft 4 and the vane pivot shaft 5. This is advantageous in cases where the optimal position of the vane 3 varies depending on the timing of the stator vane 2 and the optimal position of the vane 3 is therefore not the same for two different timings of the stator vane.

Claims

CLAIMS

1. Device (1) for setting a variable-pitch stator blade for an aircraft turbomachine, said setting device (1) comprising: - a pivotable stator blade comprising: o a stator blade base (6) and o a blade blade (2) extending in a first direction between the base and a tip, said blade being delimited in a second direction by a leading edge (21) and a trailing edge (22); - a blade pivot shaft (4) integral in rotation with the blade, having an axis of rotation extending in the first direction and - a fin (3) extending in a direction parallel to the first direction and being delimited in a third direction by a fin leading edge (31) and a fin trailing edge (32); - the wedging device (1) being characterized in that it comprises: - a light (7) located in the base (6) of the stator blade: - a portion (12) of the fin (3) comprising a part housed in the light (7); - a control means driving the blade pivot shaft (4) in rotation between a first angular position and a second angular position and moving the portion (12) of the blade between a first position corresponding to the first angular position and a second position corresponding to the second angular position; - so that a variation of a ratio between a length C and a length D is less than 10%, D being the projection of the distance between the leading edge (21) of the blade and the leading edge of the fin (31) according to a projection direction (X) normal to the first direction, C being the projection according to the projection direction (X) of the distance between the leading edge (21) of the blade and the trailing edge (22) of the blade.

2. Wedging device (1) according to the preceding claim, characterized in that it comprises: - a blade pivot shaft (5) extending radially in a direction parallel to the first direction and having an axis of rotation parallel to the axis of rotation of the blade pivot shaft (4); - a sliding connection (9) connecting the fin pivot shaft (5) and the fin (3); - said fin pivot shaft (5) being rotationally integral with the slide connection (9), the slide connection (9) allowing the fin portion (12) to slide in the slot (7) during rotation of the fin pivot shaft (5).

3. Wedging device (1) according to the preceding claim, characterized in that the sliding connection (9) comprises: - a connecting element (11) integral in rotation with the fin pivot shaft (5) and extending from the fin pivot shaft (5), - a branch (10) integral with the portion (12) of the fin (3) and capable of sliding inside the connecting element (11).

4. Wedging device (1) according to claim 2 or claim 3, characterized in that the sliding connection (9) extends in a direction normal to the axis of rotation of the fin pivot shaft (5).

5. Wedging device (1) according to one of claims 2 to 4 characterized in that the fin portion (12) housed in the light (7) extends from a branch (10) of the sliding connection (10) to a fin body (3) in a direction parallel to the axis of rotation of the fin pivot shaft (5).

6. Wedging device (1) according to one of claims 2 to 5 characterized in that the axis of rotation of the blade pivot shaft (5) is offset relative to the axis of rotation of the blade pivot shaft (4).

7. Wedging device (1) according to one of the preceding claims, characterized in that the light (7) has the shape of an arc of a circle.

8. Timing device (1) according to one of the preceding claims, characterized in that it has a plurality of variable-pitch stator vanes, a plurality of blades, a plurality of blade pivot shafts and a plurality of blade pivot shafts, the control means rotating the plurality of stator pivot shafts.

9. A rectifier stage comprising a stator ring and a timing device (1) according to the preceding claim, the variable-pitch stator vanes being distributed around the circumference of the stator ring, the projection direction (X) being the direction of air flow in the rectifier stage.

10. Aircraft turbomachine comprising a rectifier stage according to the preceding claim.

Images