TIMING DEVICE FOR VARIABLE STATOR BLADE

Abstract

VARIABLE PITCHING DEVICE FOR STATOR BLADE A pitching device for a blade (1) of a turbomachine, comprising: a blade pivotable about a first direction including a leading edge, a trailing edge and a base (6) having a slot (7); a vane (3) including a leading edge, a trailing edge and a portion (12) housed in the slot; a control means rotating the blade (4) and moving the portion of the vane; so as to maintain a variation of the C / D ratio less than 10%, the ratio being between a projection along a projection direction normal to the first direction of: length C between the leading edge and the leading edge of the vane (3) and length D between the leading edge and the trailing edge of the blade. Figure to be published with the abbreviation: Figure 2

Description

Title of the invention: TIMING DEVICE FOR STATOR VANE WITH VARIABLE TIMING 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 comprises a compressor, a combustion chamber, and a turbine. The role of the turbine is to drive the compressor in rotation by capturing some of the pressure energy from the hot gases exiting the combustion chamber and converting it into mechanical energy.

[0004] An axial compressor consists of a rotating part, the rotor, a stationary part, the stator, and a casing, the housing, the stator and the housing being rigidly connected. The rotor comprises a drum made up of an assembly of several discs on which rotating blades are mounted in a circumferential row. The stator consists of a plurality of blades mounted on the housing or on ferrules in a circumferential row, called stationary blades (because they do not rotate around the axis of rotation but can rotate about their own axis). Each row of stationary stator blades, called stator blades, constitutes a stage of the compressor. One row of rotating blades and one row of stationary blades form a compressor stage.

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

[0006] Each of these blades is movable in rotation around 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 with respect to the axis of the turbomachine and thus reduce the cross-section of the air passage through the blade stage.

[0007] A technique for improving the efficiency of turbomachinery includes the use of blades to reduce secondary airflows. For example, such secondary airflows can take the form of vortices at the interface between a blade and its base plate. An example of the use of this technique with variable-pitch blades is illustrated in [Fig. 1] and described in patent application WO 2021 / 069817 A1 filed by the applicant.

[0008] Figure 1 illustrates a blade 114 comprising a blade 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 the operation of the turbomachine, the airflow in the duct 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.l] the fins 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 fin 134 also varies. In particular, the fin 134 passes upstream of the leading edge of the blade 112 for large pitches, which makes the fin 134 ineffective.

[0011] There is no known today a technical solution for making a stator blade with variable pitch with fins 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 variable-pitch stator blade adjustment device that allows both the orientation and position of a vane to be varied. In particular, the invention makes it possible to adapt the position and orientation of the vanes to the blade's pitch position, while optimizing airflow to reduce vortex formation near the base of the blade.

[0013] A first aspect of the invention relates to a device for leveling a blade of variable-timing stator for an aircraft turbomachine, said timing device comprising: - a pivoting stator blade comprising: • a stator blade base and • a blade extending in a first direction between the base and a top, said blade being delimited in a second direction by a leading edge and a trailing edge; - a pivot shaft of the blade, fixed in rotation to the blade, having an axis of rotation extending along 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 levelling device being characterized in that it comprises: • a light located in the base of the stator blade: • a portion of the fin including a part housed in the light; - a control means driving the blade pivot shaft into rotation 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] 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 being 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 maintaining the ratio between C and D through a projection along a direction normal to the first direction, the blade retains its orientation relative to the leading edge of the blade, thus optimizing its role in reducing secondary airflow regardless of the blade's orientation. The projection direction is, for example, the direction of airflow in the aircraft turbomachine.

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

[0017] The fins make it possible to limit the flow of passage and to improve the flow close to the hub or casing. This limits the stalls on the blading and improves the operability of the stator.

[0018] The observation is that it is difficult to integrate fins on a variable pitch stator ring while taking into account the aerodynamic specifications. These stators comprising the stator ring and the blades with these variable pitch fins are used in many axial compressors to pre-orient 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 so that they adapt to 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 timing position of the stator blade.

[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 be a direction normal to the radial direction along which the stator blade extends. For example, the projection direction is the direction of airflow in a rectifier stage comprising a pitching mechanism according to the first aspect of the invention.

[0022] Furthermore, the adjustment device according to the invention makes it possible to modify the relative position of the blade and the vane to maintain a constant C / D ratio at each adjustment of the stator vane and to optimize the airflow near the base of the stator vane. This is possible thanks to the portion of the blade housed in the slot of the vane base, which guides the sliding of the linkage. With each rotation of the control ring to adjust the stator vane's position, the edges of the slot guide the blade in translation, thus changing its position through the sliding of the linkage.

[0023] The alignment device according to the first aspect of the invention thus 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 airflow for any stator blade alignment between the fully open and closed positions. complete.

[0024] In other words, the shimming 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] Furthermore, the angle of the leading edge of the fin relative to the angle of the leading edge of the stator blade is preserved.

[0026] By using the shimming 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, contrary to patent WO202169817 Al.

[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 a wider and more efficient operating range.

[0028] Advantageously, the chocking 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 joint connecting the fin pivot shaft and the fin; • said fin pivot shaft being rotationally fixed to the sliding joint, the sliding joint allowing the fin portion to slide in the slot during rotation of the fin pivot shaft.

[0029] The fin pivot shaft is rotationally fixed to an element of the sliding joint, the sliding joint thus includes another element that can slide relative to the element fixed to the fin pivot shaft and which is guided by the portion of the fin 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 airflow.

[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 vane which makes it possible 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 includes a second control ring connected to the fin pivot shaft.

[0032] Advantageously, the sliding connection comprises: • A connecting element that is rotationally fixed to the fin pivot shaft and extends 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 sliding connection to slide relative to the fin pivot shaft while rotationally securing the slide and the fin pivot shaft.

[0034] Advantageously, the sliding joint extends in a direction normal to the axis of rotation of the fin pivot shaft. This arrangement allows the position of the fin to be changed without changing its radial position.

[0035] Advantageously, the portion of the fin housed in the slot extends from the sliding joint to a fin body in a direction parallel to the axis of rotation of the fin pivot shaft. This arrangement allows the position of the fin to be changed without changing its radial position.

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

[0037] Advantageously, the light has a curved shape, for example in the shape 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 vanes in which the same control ring modifies the timing of all the vanes and all the vanes associated with the vanes, while preserving the geometric constraints on each vane blade / vane 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 shimming 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 upon reading the description which follows and the examination of the figures which accompany it. BRIEF DESCRIPTION OF THE FIGURES

[0043] Other advantages and features of the invention will become apparent from the following description, illustrated by the figures in which:

[0044] Fig. 1 illustrates a stator blade with variable pitch according to the prior art;

[0045] Figure 2 schematically illustrates the connections of one embodiment of a stator blade positioning device according to the first aspect of the invention with respect to a stator ring;

[0046] [Fig.3] illustrates a ratio of lengths of a blade and a fin 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 rectifier stage housing.

[0048] Figure 4b illustrates the device for securing Figure 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 shimming 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 on different figures has a unique reference.

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

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

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

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

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

[0057] The positioning device 1 according to the example illustrated in [Fig.2] further comprises: • a fin 3 comprising a fin body 13 and a portion of fin 12 comprising a part housed in the aperture 7; • a pivot shaft with fin 5 having an axis of rotation parallel to the first axis of rotation; • a sliding joint 9 connecting the pivot shaft of fin 5 and the fin 3, the joint being rotationally fixed to the pivot shaft of fin 5, such that the rotation of the pivot shaft of fin 5 slides the portion 12 of fin in the light 7 relative to the base 6; • a control ring 8 connected to the blade pivot shaft 4 and the vane 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 fixed connection 14 as shown in [Fig. 2]. The two bearings are integrated into a stator ring that can be fixed to a housing or hub of the turbomachine.

[0059] According to the embodiment illustrated in [Fig.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 joint 9 is perpendicular to the axis of rotation of the pivot shaft of the fin 5, in other words the arm 10 extends in a direction normal to the axis of rotation of the pivot shaft of the fin 5 which allows it to slide in the connecting element 11.

[0061] The portion of the fin 12 housed in the light 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 blade pitch.

[0062] According to an example of the shimming device 1 according to the first aspect of the invention, the base 6 of the stator blade may include a silicone skirt at the level of the light 7 houses the portion 12 of the fin. This limits the interaction of the air with the light 7 and therefore reduces aerodynamic losses.

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

[0064] In other words, the leveling device 1 is characterized by: - The blade pivot shaft 4 (also called the main shaft) under the base 6 with variable stator pitch 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 the fin pivot shaft 5, allowing simultaneous action on the angular orientation and axial position of the fin.

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

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

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

[0068] Each blade 2 is delimited along 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 airflow 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 Dl / Cl = 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 adjustment 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 Al = A2.

[0074] As illustrated in the examples in Figures 4a, 4b and [Fig. 5], the device 1 is integrated into the variable-pitch stator and is actuated by the same control ring as the stator pitch control. The vane pivot shaft 5, eccentric with respect to the vane axis, allows the required range of motion to be achieved. The slide 9 allows correction of the variation in distance between the vane 3 and its pivot shaft 5.

[0075] According to one embodiment, the alignment device comprises a multitude of stator blades and vanes. The stator blades and vanes 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 shimming 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 shim device. In this case, the stator ring may be part of a housing or be fixed to the housing of the turbomachine.

[0078] According to another embodiment, the stator ring is radially internal to the shimming 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 sliding connection and to the blade and fin pivot shafts respectively 4 and 5. [Fig.4a] shows a first wedging (first angular position) PI of the stator blade 2 relative to the stator ring and a position of the fin 3 relative to the stator blade. Figure 4b shows a second P2 position of blade 2. The fin 3 can move forward or backward to maintain its relative position with respect to blade 2 and keeps the same relative angle throughout the movement.

[0080] Figure 5 illustrates another embodiment of the shimming device 1 according to the first aspect of the invention. The shimming device is positioned on the housing this time. In other words, the stator ring is radially external to the shimming device 1. Furthermore, as explained previously, the opening 7 is narrower 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 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 according to 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: • a stator blade base (6) and • 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 blade (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) 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 (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 blade pivot shaft (5) and the blade (3); - said blade pivot shaft (5) being integral in rotation with the sliding connection (9), the sliding connection (9) allowing the sliding of the blade portion (12) in the slot (7) during rotation of the blade 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.

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