Variable stator vane and method of fabricating variable stator vane

Abstract

The present disclosure relates to a variable stator vane and a method of fabricating the variable stator vane of a gas turbine engine. The method includes providing at least one fibre sheet. The method further includes rolling the at least one fibre sheet around a mandrel to form a spindle section of the variable stator vane. An excess of material of the at least one fibre sheet remains after forming the spindle section. The method further includes using the excess of material of the at least one fibre sheet to form the at least one aerofoil section of the variable stator vane.

Claims

1. A method of fabricating a variable stator vane, the method comprising: providing at least one fibre sheet; rolling the at least one fibre sheet around a mandrel to form a spindle section of the variable stator vane, the spindle section having a spindle axis, wherein an excess of material of the at least one fibre sheet remains after forming the spindle section and a first portion of the at least one fibre sheet extends further in a direction along the spindle axis than a second portion of the at least one fibre sheet to form a projection in the spindle section; and using the excess of material of the at least one fibre sheet to form at least one aerofoil section of the variable stator vane.

2. The method of claim 1, wherein rolling the at least one fibre sheet around the mandrel comprises rolling a plurality of turns of the at least one fibre sheet around the mandrel.

3. The method of claim 1, further comprising wrapping the excess of material of the at least one fibre sheet around one or more inserts.

4. The method of claim 1, wherein rolling the at least one fibre sheet around the mandrel comprises rolling a turn of the at least one fibre sheet around an insert so that the insert is disposed between two adjacent turns of the spindle section.

5. The method of claim 1, further comprising providing a further fibre sheet over the spindle section and the at least one aerofoil section to provide an outer layer of the variable stator vane.

6. The method of claim 1, wherein using the excess of material further comprises pressing the excess of material of the at least one fibre sheet between a female aerofoil tool and a male aerofoil tool.

7. The method of claim 1, wherein the at least one fibre sheet comprises a first fibre sheet and a second fibre sheet, wherein rolling the at least one fibre sheet further comprises rolling the first fibre sheet and the second fibre sheet around the mandrel to form the spindle section, and wherein a first excess of material from the first fibre sheet remains after forming the spindle section and a second excess of material from the second fibre sheet remains after forming the spindle section.

8. The method of claim 7, wherein the at least one aerofoil section comprises a first aerofoil section and a second aerofoil section, and wherein using the excess of material comprises using the first excess of material to form the first aerofoil section and using the second excess of material to form the second aerofoil section.

9. A variable stator vane configured for rotation about a rotation axis, the variable stator vane comprising: a spindle section formed from a first portion of an at least one continuous fibre sheet wrapped around a spindle axis of the variable stator vane; and at least one aerofoil section at least partially formed from an excess of material from a second portion of the at least one continuous fibre sheet, wherein the first portion of the at least one continuous fibre sheet extends further in a direction along the spindle axis then the second portion of the at least one continuous fibre sheet to form a projection in the spindle section.

10. The variable stator vane of claim 9, wherein the spindle section comprises a plurality of turns of the at least one continuous fibre sheet wrapped around the spindle axis.

11. The variable stator vane of claim 9, further comprising at least one insert.

12. The variable stator vane of claim 9, further comprising an outer layer of fibre sheet disposed over the spindle section and the at least one aerofoil section.

13. The variable stator vane of claim 9, wherein the spindle section further comprises a mandrel, and wherein the at least one continuous fibre sheet is disposed around the mandrel.

14. The variable stator vane of claim 9, wherein the at least one continuous fibre sheet comprises a first continuous fibre sheet and a second continuous fibre sheet, and wherein the spindle section is formed from the first continuous fibre sheet and the second continuous fibre sheet rolled around the spindle axis.

15. The variable stator vane of claim 14, wherein the at least one aerofoil section comprises a first aerofoil section and a second aerofoil section, wherein the first aerofoil section is at least partially formed from an excess of material from the first continuous fibre sheet, and wherein second aerofoil section is at least partially formed from an excess of material from the second continuous fibre sheet.

16. The variable stator vane of claim 9, further comprising at least one insert disposed within the aerofoil section, wherein the at least one insert has a triangular cross section.

17. The variable stator vane of claim 9, wherein the second portion of the at least one continuous fibre sheet is trapezoidal in shape.

18. The variable stator vane of claim 9, further comprising a plurality of inserts disposed within the aerofoil section.

19. The variable stator vane of claim 9, wherein the at least one continuous fibre sheet is impregnated with a polymeric material.

20. The variable stator vane of claim 9, wherein the spindle axis and the rotation axis are colinear.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments will now be described by way of example only, with reference to the Figures, in which:

(2) FIG. 1 is a sectional side view of a gas turbine engine;

(3) FIG. 2 is a close-up sectional side view of an upstream portion of a gas turbine engine;

(4) FIG. 3 is a partially cut-away view of a gearbox for a gas turbine engine;

(5) FIG. 4A is a perspective view of a variable stator vane assembly;

(6) FIG. 4B is a perspective view of a variable stator vane;

(7) FIG. 5 is a top view of a fibre sheet used for fabricating a variable stator vane;

(8) FIG. 6 is a top view of a variable stator vane;

(9) FIG. 7 is a top view of a variable stator vane including one or more inserts;

(10) FIG. 8 is a top view of a variable stator vane including two aerofoil sections;

(11) FIG. 9A is a side view of a variable stator vane including two bushings;

(12) FIG. 9B is a partial side view of a variable stator vane including a bushing;

(13) FIG. 10 is a perspective view of the variable stator vane shown in FIG. 4A including two metal fittings;

(14) FIGS. 11A-11B are exploded and sectional views of an aerofoil tool;

(15) FIGS. 12A-12B are top and side views of a male aerofoil tool;

(16) FIG. 13 is a top view of a female aerofoil tool; and

(17) FIG. 14 is a flowchart of a method of fabricating a variable stator vane.

DETAILED DESCRIPTION

(18) Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art.

(19) FIG. 1 illustrates a gas turbine engine 10 having a principal rotational axis 9. The engine 10 comprises an air intake 12 and a propulsive fan 23 that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 comprises an engine core 11 that receives the core airflow A. The engine core 11 comprises, in axial flow series, a low pressure compressor 14, a high pressure compressor 15, combustion equipment 16, a high pressure turbine 17, a low pressure turbine 19 and a core exhaust nozzle 20. A nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass exhaust nozzle 18. The bypass airflow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low pressure turbine 19 via a shaft 26 and an epicyclic gearbox 30.

(20) In use, the core airflow A is accelerated and compressed by the low pressure compressor 14 and directed into the high pressure compressor 15 where further compression takes place. The compressed air exhausted from the high pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines 17, 19 before being exhausted through the core exhaust nozzle 20 to provide some propulsive thrust. The high pressure turbine 17 drives the high pressure compressor 15 by a suitable interconnecting shaft 27. The fan 23 generally provides the majority of the propulsive thrust. The epicyclic gearbox 30 is a reduction gearbox.

(21) An exemplary arrangement for a geared fan gas turbine engine 10 is shown in FIG. 2. The low pressure turbine 19 (see FIG. 1) drives the shaft 26, which is coupled to a sun wheel, or sun gear, 28 of the epicyclic gear arrangement 30. Radially outwardly of the sun gear 28 and intermeshing therewith is a plurality of planet gears 32 that are coupled together by a planet carrier 34. The planet carrier 34 constrains the planet gears 32 to process around the sun gear 28 in synchronicity whilst enabling each planet gear 32 to rotate about its own axis. The planet carrier 34 is coupled via linkages 36 to the fan 23 in order to drive its rotation about the engine axis 9. Radially outwardly of the planet gears 32 and intermeshing therewith is an annulus or ring gear 38 that is coupled, via linkages 40, to a stationary supporting structure 24.

(22) Note that the terms “low pressure turbine” and “low pressure compressor” as used herein may be taken to mean the lowest pressure turbine stages and lowest pressure compressor stages (i.e. not including the fan 23) respectively and/or the turbine and compressor stages that are connected together by the interconnecting shaft 26 with the lowest rotational speed in the engine (i.e. not including the gearbox output shaft that drives the fan 23). In some literature, the “low pressure turbine” and “low pressure compressor” referred to herein may alternatively be known as the “intermediate pressure turbine” and “intermediate pressure compressor”. Where such alternative nomenclature is used, the fan 23 may be referred to as a first, or lowest pressure, compression stage.

(23) The epicyclic gearbox 30 is shown by way of example in greater detail in FIG. 3. Each of the sun gear 28, planet gears 32 and ring gear 38 comprise teeth about their periphery to intermesh with the other gears. However, for clarity only exemplary portions of the teeth are illustrated in FIG. 3. There are four planet gears 32 illustrated, although it will be apparent to the skilled reader that more or fewer planet gears 32 may be provided within the scope of the claimed invention. Practical applications of a planetary epicyclic gearbox 30 generally comprise at least three planet gears 32.

(24) The epicyclic gearbox 30 illustrated by way of example in FIGS. 2 and 3 is of the planetary type, in that the planet carrier 34 is coupled to an output shaft via linkages 36, with the ring gear 38 fixed. However, any other suitable type of epicyclic gearbox 30 may be used. By way of further example, the epicyclic gearbox 30 may be a star arrangement, in which the planet carrier 34 is held fixed, with the ring (or annulus) gear 38 allowed to rotate. In such an arrangement the fan 23 is driven by the ring gear 38. By way of further alternative example, the gearbox 30 may be a differential gearbox in which the ring gear 38 and the planet carrier 34 are both allowed to rotate.

(25) It will be appreciated that the arrangement shown in FIGS. 2 and 3 is by way of example only, and various alternatives are within the scope of the present disclosure. Purely by way of example, any suitable arrangement may be used for locating the gearbox 30 in the engine 10 and/or for connecting the gearbox 30 to the engine 10. By way of further example, the connections (such as the linkages 36, 40 in the FIG. 2 example) between the gearbox 30 and other parts of the engine 10 (such as the input shaft 26, the output shaft and the fixed structure 24) may have any desired degree of stiffness or flexibility. By way of further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine (for example between the input and output shafts from the gearbox and the fixed structures, such as the gearbox casing) may be used, and the disclosure is not limited to the exemplary arrangement of FIG. 2. For example, where the gearbox 30 has a star arrangement (described above), the skilled person would readily understand that the arrangement of output and support linkages and bearing locations would typically be different to that shown by way of example in FIG. 2.

(26) Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of gearbox styles (for example star or planetary), support structures, input and output shaft arrangement, and bearing locations.

(27) Optionally, the gearbox may drive additional and/or alternative components (e.g. the intermediate pressure compressor and/or a booster compressor).

(28) Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown in FIG. 1 has a split flow nozzle 18, 20 meaning that the flow through the bypass duct 22 has its own nozzle 18 that is separate to and radially outside the core exhaust nozzle 20. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct 22 and the flow through the engine core 11 are mixed, or combined, before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the disclosure may apply, for example, to any type of gas turbine engine, such as an open rotor (in which the fan stage is not surrounded by a nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine 10 may not comprise a gearbox 30.

(29) The geometry of the gas turbine engine 10, and components thereof, is defined by a conventional axis system, comprising an axial direction (which is aligned with the principal rotational axis 9), a radial direction (in the bottom-to-top direction in FIG. 1), and a circumferential direction (perpendicular to the page in the FIG. 1 view). The axial, radial and circumferential directions are mutually perpendicular.

(30) In addition, the present invention is equally applicable to aero gas turbine engines, marine gas turbine engines and land-based gas turbine engines.

(31) Referring to FIG. 1, at least one of the compressors 14, 15 and the turbines 17, 19 includes multiple stages having rotor blades in rotor blade rows and stator vanes in stator vane rows. Any one of the stator vane rows in the gas turbine engine 10 may be a variable stator vane (VSV) row. Such a variable stator vane row includes a variable vane mechanism that allows the angle of the vanes (for example, the angle of incidence of the vanes) to be adjusted during use. Purely by way of example, the gas turbine engine 10 shown in FIG. 1 has a VSV row at an inlet to the engine core 11 of the gas turbine engine 10 in the form of a variable inlet guide vane (VIGV) row 50.

(32) FIG. 4A shows an exemplary variable stator vane assembly 100 that can be used in the gas turbine engine 10. The variable stator vane assembly 100 includes a plurality of circumferentially arranged variable stator vanes 102. The variable stator vanes 102 are arranged in an annular casing 106. FIG. 4B shows a detailed view of one of the variable stator vanes 102. Each variable stator vane 102 includes a spindle section 108 and at least one aerofoil section 110. In the example illustrated in FIG. 4B, the variable stator vane 102 includes one aerofoil section 110. The spindle section 108 is located at one end of the aerofoil section 110. An actuator (not shown) may be used to vary the angle of the variable stator vane 102. The spindle section 108 defines a spindle axis 114 along its length. The variable stator vane 102 can be rotated about the spindle axis 114. Specifically, the aerofoil section 110 may be rotated about the spindle axis 114 to adjust the angle of the variable stator vane 102.

(33) The spindle section 108 of the variable stator vane 102 is mounted to the casing 106 via a top mounting 116 and a bottom mounting 118. The top mounting 116 may be attached to the actator. The bottom mounting 118 may be movably received in a bearing (not shown). The bottom mounting 118 may rotate freely when the top mounting 116 is actuated.

(34) In this example, the spindle section 108 and the aerofoil section 110 are formed from at least one fibre sheet. In a further example, the spindle section 108 is formed from at least one continuous fibre sheet wrapped around the spindle axis 114 of variable stator vane 102. The at least one aerofoil section 110 is at least partially formed from an excess of material from the at least one continuous fibre sheet, as will be explained in more detail below.

(35) FIG. 5 shows a fibre sheet 200 used to fabricate the variable stator vane 102 of FIG. 4A. The fibre sheet 200 is interchangeably referred to as “the at least one fibre sheet 200”. In some examples, the fibre sheet 200 includes a carbon fibre sheet. In some examples, the fibre sheet 200 includes a unidirectional fibre sheet. In some other examples, the fibre sheet 200 includes a bi-directional or biaxial fibre sheet. In some other examples, the fibre sheet 200 includes a multi-directional fibre sheet. In some other examples, the fibre sheet 200 includes a combination of unidirectional, biaxial and multi-directional fibre sheets. For example, the fibre sheet 200 may be made of 0 degree fibre, 0/90 degree fibre and +/−45 degree fibre. A suitable configuration of the fibre sheet 200 may be chosen based on the expected loads on the variable stator vane 102 and to provide adequate stiffness in the 0 degree direction (i.e., vertically down the length of the spindle section 108 along the spindle axis 114). For example, 0/90 degree fibre may be used to resist air and impact loads, while +/−45 degree fibre may be used to resist torsion from when the variable stator vane 102 is actuated or impacted which can cause the variable stator vane 102 to twist.

(36) In the example illustrated in FIG. 5, the fibre sheet 200 is a continuous fibre sheet. However, the variable stator vane 102 may be formed from one or more continuous fibre sheets.

(37) The fibre sheet 200 may be impregnated with a polymeric material. In other words, a polymeric material may be applied to the fibre sheet 200. The polymeric material includes a resin, a binder or a combination thereof. For example, the polymeric material used for impregnating the fibre sheet 200 may include a bismaleimide, such as Solvay 5250-4 or Hexcel M65. In another example, the polymeric material used for impregnating the fibre sheet 200 may include a polyimide, such as MVK-14.

(38) The fibre sheet 200 includes a first portion 202 and a second portion 204. The first portion 202 is rolled to at least partially form the spindle section 108. One or more turns of the second portion 204 may also be used to form the spindle section 108. After forming the spindle section 108, an excess of material from the fibre sheet 200 may remain.

(39) Dimensions of the fibre sheet 200 may be chosen according to the desired dimensions of the variable stator vane 102. The first portion 202 may be substantially rectangular. A length and a width of the first portion 202 may be in proportion to a length and a diameter, respectively, of the spindle section 108. The second portion 204 may be approximately trapezoidal. A height and a maximum width of the second portion 204 may correspond to a height and a maximum width, respectively, of the aerofoil section 110.

(40) The fibre sheet 200 is rolled in a direction D. FIG. 6 illustrates a variable stator vane 206 formed by rolling the fibre sheet 200 of FIG. 5. The variable stator vane 206 may undergo further processes to form the variable stator vane 102 of FIG. 4A. The variable stator vane 206 includes a spindle section 210 formed by rolling the fibre sheet 200 and an at least one aerofoil section 212 at least partially formed from an excess of material 214 that remains after the rolling. In the illustrated examples, the variable stator vane 206 includes one aerofoil section 212. In some other examples, a variable stator vane may include multiple aerofoil sections. The aerofoil section 212 of the variable stator vane 206 is formed by using the excess of material 214 of the fibre sheet 200.

(41) The excess of material 214 may transfer the loads from the spindle section 210 to the aerofoil section 212. Due to the trapezoidal shape of the fibre sheet 200, the variable stator vane 206 may extend more into an airflow from an uppermost part of the spindle section 210. This may reduce loads on the material of the variable stator vane 206 and reduce a possibility of failure at the uppermost part of the spindle section 210. The aerofoil section 212 shown in FIG. 6 may be an intermediate aerofoil that has to undergo further processes to form the aerofoil section 110 of FIG. 4A.

(42) In some examples, the fibre sheet 200 is rolled around a mandrel 216 to form the spindle section 210 of the variable stator vane 206. The mandrel 216 may have a solid cylindrical configuration. A material of the mandrel 216 may depend upon the polymeric material used in the impregnation of the fibre sheet 200. In some examples, the mandrel 216 may be formed from aluminium. In some other examples, the mandrel 216 may be formed from steel. In some other examples, the mandrel 216 may include carbon. In some examples, the mandrel 216 may be retained as part of the variable stator vane 206. In some other examples, the mandrel 216 may be removed after rolling.

(43) As shown in FIG. 6, the spindle section 210 includes a plurality of turns 218 of the fibre sheet 200 wrapped around a spindle axis 220. The spindle section 210 further includes the mandrel 216. The fibre sheet 200 is disposed around the mandrel 216. Specifically, the plurality of turns 218 of the fibre sheet 200 is rolled around the mandrel 216.

(44) The polymeric material used to impregnate the fibre sheet 200 may make the surfaces of the turns 218 tacky, which may prevent the fibre sheet 200 from unrolling during fabrication. The surfaces may also be provided with an adhesive to prevent unrolling.

(45) The variable stator vane 206 further includes an outer layer of fibre sheet 222 (hereinafter referred to “the outer layer 222”) disposed over the spindle section 210 and the aerofoil section 212. In some examples, a further fibre sheet 221 is provided over the spindle section 210 and the aerofoil section 212 to provide the outer layer 222 of the variable stator vane 206. The outer layer 222 starts and terminates at a trailing edge 224 of the variable stator vane 206. In some examples, the variable stator vane 206 is sealed with the polymeric material. The polymeric material is applied over the spindle section 210 and the at least one aerofoil section 212. The sealing of the variable stator vane 206 helps ensure the fibres of the fibre sheet 200 are covered.

(46) In this example the variable stator vane 206 further includes a wedge of material 226. The wedge of material 226 may be disposed in a space that remains after rolling of the fibre sheet 200. In some examples, the wedge of material 226 may include carbon fibre. In some other examples, the wedge of material 226 may include carbon foam. The wedge of material 226 may provide additional strength and rigidity to the variable stator vane 206.

(47) FIG. 7 shows another variable stator vane 306 formed by rolling the fibre sheet 200 shown in FIG. 5. The variable stator vane 306 is similar to the variable stator vane 206 of FIG. 6. Like the variable vane 206 of FIG. 6, the variable stator vane 306 includes a spindle section 310, an aerofoil section 312, an excess of material 314, a mandrel 316, a plurality of turns 318, a spindle axis 320, an outer layer 322 and a trailing edge 324. However, the variable stator vane 306 further includes at least one insert 328.

(48) The at least one insert 328 may impart additional stiffness vertically across a width of the variable stator vane 306. The at least one insert 328 may function like a spar within the aerofoil section 312. The at least one insert 328 may be an elongate member extending at least partly along a length of the variable stator vane 306 to provide support to the variable stator vane 306. The at least one insert 328 may include one large insert or multiple smaller inserts. In the example illustrated in FIG. 7, the at least one insert 328 includes multiple smaller inserts, namely, a first insert 328A, a second insert 328B, a third insert 328C, a fourth insert 328D, and a fifth insert 328E. The inserts 328A-328E may have a same length along the spindle axis 320. The fibre sheet 200 is rolled around each of the inserts 328A-328E. The inserts 328 are disposed between adjacent turns 318 of the spindle section 310. The first insert 328A is disposed near the trailing edge 324 and has a triangular cross-section for the formation of the aerofoil section 312. The fifth insert 328E is disposed near the spindle axis 320. Each of the inserts 328B-328E has a trapezoidal cross-section having different heights and widths, though alternative shapes could be used for the inserts. In some examples, the excess of material 314 of the fibre sheet 200 is wrapped around the inserts 328A-328E.

(49) FIG. 8 shows a top view of a variable stator vane 406 formed by rolling two fibre sheets. The variable stator vane 406 has various portions similar to the variable stator vane 206 of FIG. 6 in that the variable stator vane 406 includes a spindle section 410, a mandrel 416, a spindle axis 420, and an outer layer 422. However, unlike the stator vane 206 of FIG. 6, the stator vane 406 of FIG. 8 includes two aerofoil sections 412A, 412B that extend in opposite directions.

(50) The variable stator vane 406 with two aerofoil sections 412A, 412B is formed by rolling a first fibre sheet 402 and a second fibre sheet 404 around the axis 420 to form the spindle section 410 so as to leave a first excess of material 414A and a second excess of material 414B. As can be seen from FIG. 8, the starting points on the mandrel from which the first fibre sheet 402 and the second fibre sheet 404 are rolled are different, in this case by half a turn (that is, 180 degrees). The first fibre sheet 402 is rolled around the mandrel 416 to form a plurality of first turns 418A. The second fibre sheet 404 is rolled around the mandrel 416 to form a plurality of second turns 418B adjacent to the plurality of first turns 418A. The turns 418A, 418B of the first and second sheets 402, 404 along with the mandrel 416 may form the spindle section 410 of the variable stator vane 406.

(51) The first aerofoil section 412A is at least partially formed from the first excess of material 414A from the first fibre sheet 402. The second aerofoil section 412B is at least partially formed from the second excess of material 414B from the second fibre sheet 404. The first aerofoil section 412A includes a first trailing edge 424A, while the second aerofoil section 412B includes a second trailing edge 424B. The spindle section 410 and the first and second aerofoil sections 412A, 412B are covered with a further fibre sheet 421 to provide the outer layer 422 of the variable stator vane 406. The outer layer 422 may be provided by one continuous fibre sheet. The variable stator vane 406 further includes a first wedge of material 426A and second wedge of material 426B. The first wedge of material 426A is disposed in the first aerofoil section 412A. The second wedge of material 426B is disposed in the second aerofoil section 412B.

(52) FIG. 9A shows a variable stator vane 506 with bushings. The variable stator vane 506 is similar to the variable stator vane 102 of FIG. 4A. The variable stator vane 506 includes a spindle section 510, an aerofoil section 512, and a spindle axis 520. The variable stator vane 506 may be formed from a single continuous fibre sheet similar to the variable stator vane 206 of FIG. 6.

(53) The spindle section 510 includes a top end 530 and a bottom end 532 opposite to the top end 530 with respect to the spindle axis 520. The top and bottom ends 530, 532 may extend axially relative to the aerofoil section 512. The top end 530 may fit into an actuation lever, while the bottom end 532 may be received in a guide bush. The variable stator vane 506 further includes a top bushing 534 attached to the top end 530 of the spindle section 510. In some examples, the top bushing 534 is elongate in a direction that is perpendicular to the spindle axis 520. The variable stator vane 506 further includes a bottom bushing 536 attached to the bottom end 532 of the spindle section 510. The top and bottom bushings 534, 536 may be made of metal, for example, titanium. In some examples, each of the top and bottom ends 530, 532 of the spindle section 510 may also be capped with a wear resistant material, such as titanium, in order to reduce wear and tear. For example, a titanium fitting (not shown) may be disposed on the top and bottom ends 530, 532.

(54) FIG. 9B shows a partial view of another variable stator vane 506A. The variable stator vane 506A is similar to the variable stator vane 506 of FIG. 9A and includes a spindle section 510A, an aerofoil section 512A, and a spindle axis 520A. The spindle section 510A includes a top end 530A.

(55) The variable stator vane 506A further includes a top bushing 534A connected to the top end 530A of the spindle section 510. As shown in FIG. 9B, the top bushing 534A is elongate in a direction that is perpendicular to the spindle axis 520A. The top busing 524 extends perpendicular to the spindle axis 520A and covers an uppermost portion of the aerofoil section 512A. The top bushing 534A may have a top portion 542 disposed adjacent to the top end 530A of the spindle section 510A and an elongate portion 544 extending perpendicular to the spindle axis 520A. In some applications, an actuation load may be expected to be high for a composite material. The top bushing 534A may supplement torque transfer by increasing a surface area of reaction when the variable stator vane 506A is actuated. This may reduce local stresses in the variable stator vane 506A. The increase in surface area may be achieved by extending the top bushing 534A to cover the uppermost portion of the aerofoil section 512.

(56) FIG. 10 shows the variable stator vane 102 including a top metal fitting 550 at a top end 560 of the spindle section 108 and a bottom metal fitting 552 at a bottom end 562 of the spindle section 108. Each of the top and bottom metal fittings 550, 552 may made of a material including titanium. Each of the top and bottom metal fittings 550, 552 may have a disc-shaped configuration or a penny-shaped configuration. The top metal fitting 550 is attached over the top end 560 of the spindle section 108 to react against an actuation lever. The bottom metal fitting 552 is attached over the bottom end 562 of the spindle section 108. The top metal fitting 550 and the bottom metal fitting 552 may relieve local stresses at the top end 560 and the bottom end 562, respectively, with the penny-shaped configuration.

(57) In some examples, a variable stator vane of the present disclosure may undergo a shaping process to finalize its shape. An aerofoil tool may be used for shaping the variable stator vane.

(58) FIG. 11A shows an exploded view of an aerofoil tool 600 for fabricating the variable stator vane 206. FIG. 11B shows a sectional side view of the aerofoil tool 600. The aerofoil tool 600 includes a first part 602 and a second part 604 removably connected to the aerofoil tool 600. The first part 602 includes a male aerofoil tool 610. The second part 604 includes a female aerofoil tool 612. The male aerofoil tool 610 is at least partially received within the female aerofoil tool 612. Upon assembly of the first and second parts 602, 604, the male and female aerofoil tools 610, 612 define a cavity 614 therebetween. A variable stator vane (for example, the variable stator vane 206 of FIG. 6) is received within the cavity 614. The excess of material 214 of the fibre sheet 200 may be pressed between the male aerofoil tool 610 and the female aerofoil tool 612. The male aerofoil tool 610 and the female aerofoil tool 612 may provide a final shape to the variable stator vane 206.

(59) FIGS. 12A and 12B show a top view and a side view, respectively, of the first part 602 including the male aerofoil tool 610. The male aerofoil tool 610 protrudes from a surface 620 of the first part 602. FIG. 13 shows a top view of the second part 604 including the female aerofoil tool 612. The female aerofoil tool 612 may be a recess extending from a surface 622 of the second part 604. A shape of the male aerofoil tool 610 and a shape of the female aerofoil tool 612 may depend on a desired shape of a variable stator vane. A variable stator vane fabricated by rolling one or more continuous fibre sheets around a mandrel may be pressed between the male aerofoil tool 610 and the female aerofoil tool 612 to provide the desired shape.

(60) FIG. 14 is a flow chart showing a method 700 of fabricating a variable stator vane. Reference will also be made to FIGS. 4-13.

(61) At 702, the method 700 includes providing the at least one fibre sheet 200 for the fabrication of the variable stator vane 206. The at least one fibre sheet 200 may include a carbon fibre sheet. In some examples, the method 700 further includes impregnating the fibre sheet 200 with a polymeric material prior to rolling the fibre sheet 200 at 704. The polymeric material may be applied on the fibre sheet 200 such that the fibre sheet 200 includes an adhesive surface. The impregnation of the fibre sheet 200 may prevent unrolling of the fibre sheet 200 during fabrication. In some examples, the polymeric material includes a resin or a binder. In some examples, the at least one fibre sheet includes the first fibre sheet 402 and the second fibre sheet 404.

(62) At 704, the method 700 further includes rolling the at least one fibre sheet 200 around the mandrel 216 to form the spindle section 210 of the variable stator vane 206. In some examples, rolling the at least one fibre sheet 200 around the mandrel 216 includes rolling the plurality of turns 218 of the fibre sheet 200 around the mandrel 216. In some examples, rolling the at least one fibre sheet 200 around the mandrel 316 includes rolling the turn 318 of the fibre sheet 200 around the insert 328 so that the insert 328 is disposed between two adjacent turns 318 of the spindle section 310.

(63) In some examples, the female aerofoil tool 612 may be used for rolling the at least one fibre sheet 200 around the mandrel 216

(64) In some other examples, rolling the at least one fibre sheet further includes rolling the first fibre sheet 402 and the second fibre sheet 404 around the mandrel 216 to form the spindle section 410.

(65) The excess of material 214 of the at least one fibre sheet 200 remains after forming the spindle section 210. In some examples, the first excess of material 414A from the first fibre sheet 402 remains after forming the spindle section 410 and the second excess of material 414B from the second fibre sheet 404 remains after forming the spindle section 410.

(66) In some examples, the method 700 further includes wrapping the excess of material 314 of the at least one fibre sheet 200 around the one or more inserts 328A-328E.

(67) At 706, the method 700 further includes using the excess of material 214 of the at least one fibre sheet 200 to form the at least one aerofoil section 212 of the variable stator vane 206. In some other examples, the at least one aerofoil section includes the first aerofoil section 412A and the second aerofoil section 412B. In some examples, using the excess of material includes using the first excess of material 414A to form the first aerofoil section 412A and using the second excess of material 414B to form the second aerofoil section 412B.

(68) In some examples, using the excess of material 214 further includes pressing the excess of material 214 of the at least one fibre sheet 200 between the male aerofoil tool 610 and the female aerofoil tool 612.

(69) Optionally, at 708, the method 700 may further include providing the further fibre sheet 221 over the spindle section 210 and the aerofoil section 212 to provide the outer layer 222 of the variable stator vane 206.

(70) The method 700 may further include applying a resin on the spindle section 210 and the aerofoil section 212. The resin may be used to seal the variable stator vane 206. The sealing of the variable stator vane 206 is done to ensure all the fibres of the fibre sheet 200 are covered.

(71) One or more steps of the method 700 may be done manually or automatically. In some examples, a variable stator vane may be fabricated in one or more intermediate stages. For example, at least one fibre sheet may be successively wrapped around multiple inserts. A hand tool may be used to compact each individual insert as the corresponding wrap is applied to ensure conformity. The variable stator vane may be removed from the hand tool at each wrap and disposed in the female aerofoil tool 612. The next insert may be then applied, and another wrap applied over the next insert. The hand tool may be then used to compress the next insert to consolidate the variable stator vane.

(72) The method 700 of fabricating the variable stator vane may be cost effective and time efficient. The method 700 may also result in a variable stator vane with reduced weight as compared to variable stator vanes manufactured by conventional methods. The method 700 may also reduce or eliminate tooling costs generally associated with other methods.

(73) The method 700 may enable fabrication of the variable stator vane from a composite material. The composite material may substantially reduce the mass of variable stator vane as compared to a variable stator vane made of metal, such as titanium.

(74) It will be understood that the invention is not limited to the embodiments above described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.