Abstract
A stator vane for a gas turbine engine is provided. The stator vane has a platform surface from which an aerofoil extends, and a joggle surface that is circumferentially and radially displaced from the platform surface. Multiple stator vanes are arranged together to form a stator vane row, with each stator vane in the row remaining independent of the others. When the stator vanes are assembled together in a row, the joggle surface of one vane circumferentially overlaps a recess surface formed in a neighbouring vane. Because of the increased circumferential extent of the vanes, the vane is able to rotate in a retaining slot less than a conventional vane. This results in less wear and/or damage to the components.
Claims
1. An annular stator vane row for an axial flow gas turbine engine stage, the annular stator vane row comprising more than two stator vanes and the gas turbine engine defining axial, radial and circumferential directions of the stator vanes, each stator vane comprising: an aerofoil; and a fixing portion arranged to fix the stator vane in the gas turbine engine, the fixing portion comprising a step formed by (i) a platform surface from which the aerofoil extends, and (ii) a joggle surface, wherein: both the platform surface and the joggle surface extend substantially perpendicularly to the radial direction; the joggle surface is radially offset from the platform surface and extends circumferentially away from the platform surface, such that the overall circumferential extent (C2) of the fixing portion is greater than the circumferential extent (C1) of the platform surface alone; the fixing portion further comprises a recess, the recess defining a recess surface that is substantially perpendicular to the radial direction, radially offset from the platform surface and circumferentially overlapping with at least a part of the platform surface, the recess surface being geometrically the same as the joggle surface, and the joggle surface being circumferentially offset from the recess surface; the joggle surface of one stator vane is provided in the recess of a neighbouring second stator vane so as to oppose the recess surface of the neighbouring stator vane; each stator vane is metallic; and each stator vane is independent of, and not permanently joined to, the other stator vanes.
2. The annular stator vane row according to claim 1, wherein the axial extent of the joggle surface is substantially the same as the axial extent of the platform surface.
3. The annular stator vane row according to claim 1, wherein the axial extent of the joggle surface is less than the axial extent of the platform surface.
4. The annular stator vane row according to claim 1, wherein the recess surface has a surface normal that points in the opposite direction to that of the joggle surface.
5. The annular stator vane row according to claim 1, wherein the joggle surface comprises a circumferentially extending locking tooth that extends over only a part of the axial extent of the joggle surface.
6. The annular stator vane row according to claim 1, wherein, in use, the platform surface is a gas-washed surface.
7. The annular stator vane row according to claim 1, wherein each stator vane is retained in a circumferentially extending retaining slot by its fixing portion.
8. The annular stator vane row according to claim 7, wherein the retaining slot comprises an anti-fret liner with which the fixing portion of the vanes are engaged.
9. A gas turbine engine comprising at least one stator vane row according to claim 1.
10. A method of manufacturing an annular stator vane row according to claim 1, comprising manufacturing each of the stator vanes using metal injection moulding.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Arrangements will now be described by way of example only, with reference to the Figures, in which:
[0031] FIG. 1 shows schematically fixing portions of two adjacent vanes of a stator vane row;
[0032] FIG. 2 shows schematically platforms of two adjacent stator vanes located in a casing slot (a) for un-joined vanes, and (b) for vanes permanently joined at neighbouring axially-extending edges of their platforms;
[0033] FIG. 3 is a sectional side view of a gas turbine engine;
[0034] FIG. 4 is a schematic side view of a stator vane in accordance with an example of the present disclosure;
[0035] FIG. 5 is a schematic perspective view of the stator vane shown in FIG. 4;
[0036] FIG. 6 is another schematic perspective view of the stator vane shown in FIG. 4;
[0037] FIG. 7 is a schematic view showing part of a stator vane row comprising the stator vanes shown schematically in FIGS. 4 to 6;
[0038] FIGS. 8A and 8B are schematic views showing vanes rotating in a retaining slot;
[0039] FIG. 9 is a schematic showing leakage flow through a stator vane row;
[0040] FIG. 10 is a schematic perspective view showing a double-ended stator vane in accordance with an example of the present disclosure;
[0041] FIG. 11 is a schematic perspective view of a stator vane in accordance with an example of the present disclosure;
[0042] FIG. 12 is a schematic view showing part of a stator vane row comprising stator vanes shown schematically in FIG. 11;
[0043] FIG. 13 is another schematic view showing part of a stator vane row comprising stator vanes shown schematically in FIG. 11;
[0044] FIG. 14 is a schematic perspective view of another stator vane in accordance with an example of the present disclosure;
[0045] FIG. 15 is another schematic view of the stator vane shown in FIG. 14;
[0046] FIG. 16 is a schematic view showing part of a stator vane row comprising stator vanes shown schematically in FIGS. 14 and 15; and
[0047] FIG. 17 is another schematic view showing part of a stator vane row comprising stator vanes shown schematically in FIGS. 14 and 15.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0048] With reference to FIG. 3, a gas turbine engine is generally indicated at 10, having a principal and rotational axis 11. The engine 10 comprises, in axial flow series, an air intake 12, a propulsive fan 13, an intermediate pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, an intermediate pressure turbine 18, a low-pressure turbine 19 and an exhaust nozzle 20. A nacelle 21 generally surrounds the engine 10 and defines both the intake 12 and the exhaust nozzle 20.
[0049] The gas turbine engine 10 works in the conventional manner so that air entering the intake 12 is accelerated by the fan 13 to produce two air flows: a first air flow into the intermediate pressure compressor 14 and a second air flow which passes through a bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 14 compresses the air flow directed into it before delivering that air to the high pressure compressor 15 where further compression takes place.
[0050] 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 combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines 17, 18, 19 before being exhausted through the nozzle 20 to provide additional propulsive thrust. The high 17, intermediate 18 and low 19 pressure turbines drive respectively the high pressure compressor 15, intermediate pressure compressor 14 and fan 13, each by suitable interconnecting shaft.
[0051] At least one of the compressors 14, 15 and the turbines 17, 18, 19 comprise stages having rotor blades in rotor blade rows (labelled 60 by way of example in relation to the intermediate pressure compressor in FIG. 3) and stator vanes in stator vane rows (labelled 70 by way of example in relation to the intermediate pressure compressor in FIG. 3).
[0052] Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines. Further the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.
[0053] The geometry of the gas turbine engine 10, and components thereof, is defined by a conventional axis system, comprising an axial direction 30 (which is aligned with the rotational axis 11), a radial direction 40, and a circumferential direction 50 (shown perpendicular to the page in the FIG. 3 view). The axial, radial and circumferential directions 30, 40, 50 are mutually perpendicular.
[0054] A metallic stator vane 100 in accordance with the present disclosure is shown in FIGS. 4 to 6. The stator vane 100 may be used in one or more stator vane rows 70 in a gas turbine engine 10 such as that shown in FIG. 3.
[0055] The stator vane 100 comprises an aerofoil 110 and a fixing portion 120. The fixing portion 120 is arranged to fix the stator vane 100 in a gas turbine engine 10, for example using tangs 122.
[0056] The aerofoil 110 extends from a platform surface 130. The platform surface 130 is considered to be part of the fixing portion 120. The fixing portion 120 also comprises a joggle surface 140. The joggle surface 140 may be said to be part of a joggle portion that extends circumferentially away from the platform surface 130.
[0057] The joggle surface 140 is offset from the platform surface in the radial direction 40. In the illustrated example, the fixing portion 120 is provided at the radially outer end of the stator vane 100, and so the joggle surface 140 is radially outside (i.e. at a greater radial extent) than the platform surface 130. The joggle surface 140 is offset from the platform surface 130 in the circumferential direction 50. The overall circumferential extent C2 of the vane 100, for example the overall circumferential extent C2 of the fixing portion 120, is greater than the circumferential extent C1 of the platform surface 130 alone. The combination of the circumferential offset and the radial offset of the joggle surface from the platform surface may be said to form a step in the fixing portion 120.
[0058] The vane 100 also comprises a recess 150 in the fixing portion 120, as shown in the example of FIGS. 4 to 7. The recess 150 may be said to be formed by circumferentially extending ledge that comprises a part of the platform surface 130. The recess 150 defines a recess surface 155. The recess surface 155 is substantially parallel to, and radially offset from, the platform surface 130. The recess surface 155 is substantially parallel to, and circumferentially offset from, the joggle surface 140. The geometry of the recess surface 155 and the joggle surface 140 may be substantially the same.
[0059] FIG. 7 shows a portion of a stator vane row 70 having a plurality of the stator vanes 100 assembled together. In the FIG. 7 example, the joggle surface 140 (or joggle portion) is slotted into the recess 150. The joggle surface 140 of one vane 100 may engage the recess surface of a neighbouring vane 100, as shown in FIG. 7. Each vane 100 remains independent of the other vanes 100. Even when assembled into a gas turbine engine 10, each vane 100 may be moveable in at least one degree of freedom relative to the other vanes 100. For example, each vane 100 may be rotatable about a radial direction 40 relative to the other vanes 100, within a retaining slot.
[0060] FIG. 8A shows a conventional vane 1 (such as that shown in FIG. 1, discussed above) that has rotated during use in its retaining slot 200 to a position in which the vane 1 contacts the retaining slot 200 at contact points 7. The retaining slot 200 may comprise an anti-fret lining along the contact surface. As shown in FIG. 8A, the conventional vane 1 rotates through an angle of θ1 before contacting the retaining slot 200. As mentioned above, the larger this angle, the greater the chance of damage and/or increased wear, for example due to greater forces being generated between the vane 1 and the retaining slot 200.
[0061] FIG. 8B shows a stator vane 100 in accordance with the present disclosure (such as that shown in FIGS. 4 to 7, discussed above) that has rotated during use in its retaining slot 200 to a position in which the vane 100 contacts the retaining slot 200 (which may be, for example, a T-shaped retaining slot 200) at contact points 207. Compared with the conventional vane 1 shown in FIG. 8B, the stator vane 100 rotates through a smaller angle, θ2, before contacting the retaining slot 200. This is because of the increased effective width (that is, increased circumferential extent) C2 of the stator vane 100 compared with the width C1 of the conventional vane 1. Any increase in effective width may be beneficial. Purely by way of example, the circumferential extent (or effective width) C2 of the stator vane 100 may be in the range of from 1% to 100%, for example 10% to 90%, for example 20% to 75%, for example 25% to 50%, for example on the order of 30% greater than the circumferential extent (or effective width) C1 of the stator vane 1.
[0062] This reduced rotation before contact with the cases reduces the likelihood and/or magnitude of any wear/damage caused by the contact between the vane 100 and the casing 200. Note that the size of the platform surface 130 (i.e. the surface from which the aerofoil 110 extends) may be the same for the convention vane 1 of FIG. 8A and the vane 100 in accordance with the present disclosure shown in FIG. 8B. For example, the width (or circumferential extent) of the platform surface of both vanes 1, 100 may be C1.
[0063] FIG. 9 illustrates another potential advantage of stator vanes 100 in accordance with the present disclosure. In particular, FIG. 9 illustrates a leakage path 250 for leakage flow to leak between the working fluid passing over the aerofoils 110 (and thus providing useful work, or energy output), and the region radially outside the vanes 100 (which does not provide useful work, or energy output). Such leakage flow may be problematic for all vane rows. However, as shown in FIG. 9, the leakage flow path 250 formed by arrangements in accordance with the present disclosure is tortuous. In the FIG. 9 example, the leakage flow path turns from radial 40, to circumferential 50, then back to radial 40. This may significantly reduce flow losses, and thus increase efficiency, compared to a conventional vane design, in which the leakage path is purely radial 40.
[0064] A stator vane in accordance with the present disclosure may be either a singled ended vane (as in the example described above in relation to FIGS. 4 to 7), or a double ended vane 300, as in the example shown in FIG. 10. The double ended vane 300 shown in FIG. 10 has a sealing tip 310. The sealing tip 310 may help to reduce over-tip flow during use. Any sealing tip 310 may be used. In all other aspects, the double ended vane 300 shown in FIG. 10 may be the same as the single ended vane shown in FIGS. 4 to 7, with like reference numerals representing like features. Any description provided herein in relation to a single ended vane 100 may also apply to a double ended vane 300 (for example in relation to the fixing portion 120), and so will not be repeated in relation to FIG. 10.
[0065] FIGS. 11 to 13 show a further example of a stator vane 400 in accordance with the present disclosure. The stator vane 400 shares many features with the stator vane 100 shown and described in relation to FIGS. 4 to 7. For example, the aerofoil 410, platform surface 430 and tangs 422 may be substantially the same as the aerofoil 110, platform surface 130 and tangs 122 described in relation to FIGS. 4 to 7, and so will not be described further in relation to FIGS. 11 to 13.
[0066] However, whereas the axial extent of the joggle surface 140 of the vane 100 shown in FIGS. 4 to 7 is substantially the same as the axial extent of the platform surface 130, the axial extent of the joggle surface 440 of the vane 400 shown in FIGS. 11 to 13 is less than the axial extent of the platform surface 430. Similarly, the axial extent of the recess surface 455 is less than the axial extent of the platform surface 430 in the vane 400 shown in the example of FIGS. 11 to 13. The axial extent of the recess surface 455 may be the same as the axial extent of the joggle surface 440. More generally, the geometry of the recess surface 455 may be the same as the geometry of the joggle surface 440.
[0067] FIGS. 12 and 13 show a plurality of the vanes 400 arranged together to form part of a stator vane row 70. As shown in these Figures, the configuration of the recess surface 455 and the joggle surface 440 may create an interlocking feature that may help to lock neighbouring vanes 400 together and/or may help to reduce unwanted rotation of the vanes 400 (for example about a radial direction 40. Stator vanes according to the present disclosure may, optionally, be provided with any suitable interlocking feature, of which the arrangement shown in FIGS. 11 to 13 is just one example.
[0068] FIGS. 14 to 17 show a further example of a stator vane 500 in accordance with the present disclosure. The stator vane 500 shown in FIGS. 14 to 17 shares many corresponding features with the stator vane 100 shown in, and described in relation to, FIGS. 4 to 7. For example, the aerofoil 510, and platform surface 530 are substantially the same as the aerofoil 110 and platform surface 130 of the stator vane 100 shown in FIGS. 4 to 7, and will not be described in detail again here.
[0069] The joggle surface 540 of the stator vane 500 shown in FIGS. 14 to 17 comprises a locking tooth 545. The locking tooth 545 in this example is a circumferential extension 545 of the joggle surface 540. The circumferential extension 545 may be an extension of the rest of the joggle surface and/or may form a continuous and/or contiguous surface with the rest of the joggles surface 540. However, it will be appreciated that other geometries of locking tooth 545 may be used.
[0070] The recess surface 555 of the fixing portion 520 also has a circumferentially extending extension 557 in the FIGS. 14 to 17 example. The extension 557 of the recess surface 555 may correspond to, for example have the same geometry as, the circumferential extension 545 of the joggle surface 540. As shown in FIGS. 16 and 17, when more than one stator vane 500 are arranged together to form a stator vane row 70, the joggle surface 540 of one vane may be adjacent (and optionally engaging) the recess surface 555 of an adjacent vane 500, as with any arrangement. In the example of FIGS. 14 to 17, this means that the extension 557 of the recess surface 555 is adjacent (and optionally engaging) the extension 545 of the joggle surface 540.
[0071] Any suitable method may be used to manufacture the metallic vanes 100, 400, 500 shown and described herein. For example, each individual vane 100, 400, 500 may be manufactured using metal injection moulding (MIM).
[0072] 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.
