GUIDE VANE ASSEMBLY WITH SEALING ELEMENT

Abstract

The proposed solution relates to a stator vane assembly for an engine, having at least one stator vane of a stator vane row and a casing for the at least one stator vane row, wherein the at least one stator vane is mounted adjustably on the casing by means of a bearing journal, which is rotatably mounted in a bearing opening in the casing and passes through this bearing opening along a longitudinal axis.

A section of a sealing element, on which at least one sealing ridge extending radially in relation to the longitudinal axis is formed and/or which has a nonlinear slot passing longitudinally through the section, is provided within the bearing opening.

Claims

1. A stator vane assembly for an engine, having at least one stator vane of a stator vane row and a casing for the at least one stator vane row, wherein the at least one stator vane is mounted adjustably on the casing by means of a bearing journal, which is rotatably mounted in a bearing opening in the casing and passes through this bearing opening along a longitudinal axis, wherein a section of a sealing element, on which at least one sealing ridge extending radially in relation to the longitudinal axis is formed and/or which has a nonlinear slot passing longitudinally through the section, is provided within the bearing opening.

2. The stator vane assembly according to claim 1, wherein the section of the sealing element which is provided within the bearing opening forms a labyrinth seal in order to avoid a leakage flow through the bearing opening and along the bearing journal.

3. The stator vane assembly according to claim 1, wherein at least two sealing ridges, which are arranged in series along the longitudinal axis, are formed on the section provided within the bearing opening.

4. The stator vane assembly according to claim 1, wherein the at least one radially extending sealing ridge tapers in the direction of the bearing journal in at least one ridge section.

5. The stator vane assembly according to claim 1, wherein the at least one radially extending sealing ridge extends into a recess in the bearing journal.

6. The stator vane assembly according to claim 1, wherein the at least one radially extending sealing ridge has an end region which rests in frictional engagement against an outer lateral surface of the bearing journal and which is provided for the purpose of being scraped off at least partially by the adjustment of the bearing journal around the longitudinal axis during the operation of the engine.

7. The stator vane assembly according to claim 1, wherein the section formed with the at least one radially extending sealing ridge is accommodated in a recess in the bearing journal, and the at least one sealing ridge extends radially outward in the direction of an inner lateral surface of the bearing opening.

8. The stator vane assembly according to claim 1, wherein, in addition to the section formed with the at least one radially extending sealing ridge, the sealing element has a bearing section, via which the sealing element rests against a rim surface of the casing, said surface being situated radially on the inside in relation to a central axis of the stator vane row of the at least one stator vane and forming a boundary of the bearing opening.

9. The stator vane assembly according to claim 1, wherein at least two sealing elements are provided, on each of which a section is provided within the bearing opening, on which section at least one sealing ridge extending radially in relation to the longitudinal axis is formed and/or which has a nonlinear slot passing longitudinally through the section.

10. The stator vane assembly according to claim 1, wherein the sealing element is of bush-shaped or disk-shaped design.

11. The stator vane assembly according to claim 1, wherein the nonlinear slot which passes longitudinally through the section of the sealing element which is provided within the bearing opening has a discontinuous path.

12. The stator vane assembly according to claim 1, wherein the nonlinear slot which passes longitudinally through the section of the sealing element which is provided within the bearing opening has a helical, Z-, V- or -shaped path.

13. The stator vane assembly according to claim 1, wherein the sealing element is of multi-part design, and two parts of the sealing element adjoin one another along the slot.

14. A gas turbine engine having a stator vane assembly according to claim 1.

Description

[0027] In the figures:

[0028] FIG. 1A shows a detail of one variant of a proposed stator vane assembly in the region of a bearing opening of a casing, wherein a stator vane bearing journal held rotatably in the bearing opening is provided by means of a bush-shaped sealing element with a plurality of (at least two) rows of radially extending sealing ridges;

[0029] FIG. 1B shows a side view of the bush-shaped sealing element, illustrating, in particular, a Z-shaped slot passing longitudinally through a stem section of the sealing element;

[0030] FIG. 1C shows a plan view of the bush-shaped sealing element in FIGS. 1A and 1B;

[0031] FIG. 2 shows another variant embodiment of a proposed stator vane assembly in a view corresponding to that in FIG. 1A, wherein two separate bush-shaped sealing elements are provided;

[0032] FIG. 3 shows a stator vane assembly having a bush-shaped sealing element, illustrating radially extending sealing ridges of different configurations, in a view corresponding to that in FIGS. 1A and 2;

[0033] FIG. 4 shows another variant embodiment of a proposed stator vane assembly having a disk-shaped, longitudinally slotted sealing element, in a view corresponding to that in FIGS. 1A, 2 and 3;

[0034] FIG. 4A shows the disk-shaped sealing element in an isolated view in a section along a section line A-A in FIG. 4;

[0035] FIGS. 4B-4E show a side view of the disk-shaped sealing element with a V-, Z-, -shaped or helical slot in the disk-shaped sealing element along a line of sight B corresponding to FIG. 4A;

[0036] FIGS. 5A-5C show further variant embodiments of a proposed stator vane assembly having different bush-shaped sealing elements, each having a plurality of rows of radially extending sealing ridges, in each case in a longitudinally sectioned view;

[0037] FIGS. 5D-5F show perspective sectioned views of the bush-shaped sealing elements in FIGS. 5A, 5B and 5C;

[0038] FIGS. 6A-6B show one variant embodiment of a bush-shaped sealing element having a Z-shaped slot under two different thermal boundary conditions in side view;

[0039] FIG. 7 shows, in a schematic sectional illustration, a gas turbine engine in which at least one stator vane assembly according to the invention is used;

[0040] FIG. 8 shows a detail in perspective view of an arrangement known from the prior art comprising a plurality of stator vane assemblies, each having a stator vane row and a plurality of rotor blade assemblies.

[0041] FIG. 7 illustrates, schematically and in a sectional illustration, a (gas turbine-) engine T in the form of a turbofan engine, in which the individual engine components are arranged one behind the other along a central axis or axis of rotation M. At an inlet or intake E of the engine T, air is drawn in along an inlet direction E by means of a fan F. This fan F is driven via a connecting shaft, to which rotation is imparted by a turbine TT. Here, the turbine TT adjoins a compressor V, which comprises for example a low-pressure compressor 11 and a high-pressure compressor 12, and possibly also a medium-pressure compressor. On the one hand, the fan F feeds air to the compressor V and, on the other hand, feeds air to a secondary-flow or bypass duct to generate the thrust. Finally, the air delivered via the compressor V enters a combustor section BK, in which the driving energy for driving the turbine TT is generated. For this purpose, the turbine TT has a high-pressure turbine 13, a medium-pressure turbine 14 and a low-pressure turbine 15. The energy released during combustion is used by the turbine TT to drive the fan F in order then to generate the required thrust by means of the air conveyed into the bypass duct B. During this process, the air leaves the bypass duct B in the region of an outlet A at the end of the engine T at which the exhaust gases flow outward out of the turbine TT. In this case, the outlet A usually has a thrust nozzle.

[0042] In principle, the fan F can also be coupled by a connecting shaft and an epicyclic planetary transmission to the low-pressure turbine 15 and can be driven by the latter. It is furthermore also possible to provide other gas turbine engines of different configuration in which the proposed solution can be used. For example, engines of this type can have an alternative number of compressors and/or turbines and/or an alternative number of connecting shafts. By way of example, the engine can have a split flow nozzle, meaning that the flow through the bypass duct B has its own nozzle that is separate from and radially outside the core engine nozzle. 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 B and the flow through the core 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 flow or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the proposed solution may be applied, 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.

[0043] In the variant of an engine T which is illustrated by way of example in the present case, the compressor V comprises a plurality of rows of rotor blades 110 situated axially in series and interposed rows of stator vanes 111 in the region of the low-pressure compressor 11. The rows of rotor blades 110, which rotate around the central axis M, and the rows of stationary stator vanes 111 are arranged alternately along the central axis M and accommodated in a (compressor) casing 1 of the compressor V. The individual stator vanes 111 are mounted adjustably on the single- or multi-part casing 1generally in addition to radially inner mounting on the hub of the compressor V.

[0044] Here, FIG. 8 shows a segment at a greater level of detail of an arrangement known from the prior art of rotor blade rows 12a to 12d and stator vane rows 13a to 13c for the low-pressure compressor 11. The stator vanes 111 of the stator vane rows 13a, 13b and 13c arranged in series are mounted adjustably on the casing 1 in order to enable the position of the stator vanes 111 to be changed in accordance with the compressor speed and inlet gas temperature. For this purpose, a bearing journal 111a of each rotor blade 111 is mounted rotatably in a bearing opening O, which is formed by a sleeve-shaped, radially outward-projecting bearing extension 10 of the casing 1. Each bearing journal 111a is rotatably mounted and supported in an associated bearing extension 10. In this arrangement, each bearing journal 111a passes through its associated bearing extension 10 along a longitudinal axis L, with the result that one journal end 111b projects from the bearing extension 10 on the outside of the casing 1.

[0045] It is thus possible for a respective adjusting lever 31 of an adjusting device 3 to act on the individual journal ends 111b to enable the bearing journal 111a to be rotated and thus the position of the associated stator vane 111 to be changed. In this arrangement, the levers 31 of a stator vane row 13a, 13b or 13c are each articulated on an adjusting element in the form of an adjusting ring 30 of the adjusting device 3. The adjusting ring 30which is often in several parts and divided into at least two segmentsextends circumferentially along the outer lateral surface of the casing 1. By adjusting the adjusting ring 30, it is thus possible to adjust the adjusting levers 31 articulated thereon and to adjust several (usually all) of the stator vanes 111 of a stator vane row 13a, 13b or 13c. Here, the individual adjusting rings 30 for the individual stator vane rows 13a, 13b and 13c are generally adjustable independently of one another.

[0046] Owing to component tolerances, wear during the operation of the engine T and the necessity of preserving a clearance in the region of the adjustable bearing journal 111a within the bearing opening O, there is in practice often an unwanted leakage flow out of an annular space RR (in which the stator vane rows 13a-13d are arranged) in the interior of the casing 1 toward the outside, as a result of which the mass flow in the core engine may possibly be reduced only slightly but not inconsiderably.

[0047] In a variant embodiment, illustrated in FIG. 1A, of a proposed stator vane assembly, such unwanted leakage flow is reduced or even completely avoided by an additionally provided sealing element in the form of a sealing bush 4. The sealing bush 4 has a bearing section in the form of a collar-shaped bush rim 41 via which the sealing bush 4 rests on an inner rim surface 10b, which is situated radially on the inside in relation to the central axis M and thus faces the annular space RR. From this bush rim 41, a stem section 40 extends into the interior of the bearing opening O, said section in the present case having a plurality of (at least two) rows of sealing ridges 400 which project radially (in relation to the longitudinal axis L) and extend around the longitudinal axis L.

[0048] The sealing ridges 400 each project in the direction of the bearing journal 111a from an inner lateral surface of the stem section 40 and each extend with a tapering end region into a recess 111.4 in the bearing journal 111a.

[0049] In the present case, a narrow clearance g1 is provided between an inner lateral surface 100 of the bearing extension 10 of the casing 1 in the bearing opening O and an outer lateral surface of the stem section 40. By virtue of the sealing contact of the bush rim 41 on the inner rim surface 10b, however, a flow to the outside via this clearance g1 is avoided. As an alternative, a press fit can be provided for the stem section 40.

[0050] Admittedly, there continues to be a clearance g2 between the inner lateral surface of the stem section 40 and an outer lateral surface of the bearing journal 111a for the rotatable mounting of the bearing journal 111a in the bearing opening O. However, a labyrinth seal, by means of which a leakage flow along the longitudinal axis L to the outside is avoided, is formed here by means of the plurality of rows of sealing ridges 400 and the recesses 111.4 provided in the bearing journals 111a.

[0051] The sealing bush 4 is in two parts with two bush halves (or half bushes), which are separated from one another by two longitudinally extending slots 401, with the result that the two bush halves adjoin one another along the slots 401 in the assembled state. In the case of a sealing bush 4 designed as a single part, the sealing bush 4 is longitudinally slotted in a manner similar to the individual illustrations in FIGS. 1B and 1C to enable the sealing bush 4 to be mounted on the bearing journals 111a. By means of these slots 401, the sealing bush 4 can be expanded for assembly on the bearing journals 111a. A temperature-induced expansion of the mounted sealing bush 4, particularly in the region of the stem section 40, is furthermore allowed by the slots 401.

[0052] In order to avoid the sealing action of the sealing bush 4 being negatively affected by the provision of the slots 401, each slot 401 has a nonlinear, discontinuous path, with the result that circumferential sections 40a and 40b of the stem section 40 which belong to different bush halves overlap one another at least partially in the axial direction. In the variant embodiment in FIGS. 1A to 1C, the slot 401 is in each case of Z-shaped design.

[0053] It should furthermore be noted that the sealing bush 4 is provided at a radially inner end of the bearing opening O in relation to the central axis M, in addition to a bearing bush 2, by means of which the bearing journal 111a is rotatably mounted within the bearing opening O. This bearing bush 2 has a collar-shaped bush rim, which is fixed by means of an (optional) adhesive surface 20 on the underside thereof on a radially outer rim surface 10a of the bearing extension 10. In this way, the bearing bush 2 is also fixed in a sealing manner on the bearing extension 10 and, consequently, there is only a clearance between an inner lateral surface of the bearing bush 2 and an outer lateral surface of the bearing journal 111a.

[0054] In the variant embodiment in FIG. 2, an additional sealing element in the form of a further sealing bush 5 is provided along the longitudinal axis L in addition to the sealing bush 4. This further sealing bush 5 likewise has a plurality of sealing ridges 500 extending circumferentially around the longitudinal axis L and projecting radially in relation to the longitudinal axis L. These sealing ridges 500, which taper in the direction of the bearing journal 111a, likewise extend into additionally provided recesses 111.5 in the bearing journal 111a and thus define an additional labyrinth seal on the outer lateral surface of the bearing journal 111a at a distance from the sealing bush 4 and the sealing ridges 400 thereof.

[0055] Instead of a bearing bush, a bearing washer 2 is provided by way of example in the radially outer rim surface 10a in the variant embodiment in FIG. 2. This bearing washer 2 too is fixed on the end-located rim surface 10b by means of an (optional) adhesive surface 20. By means of the bearing washer 2 in FIG. 2, only axial mounting of the adjusting lever 31 is thus provided (as also with the bush rim of the bearing bush 2) but not rotatable mounting of the bearing journal 111a. Thus only the sealing bushes 4 and 5 are provided for the rotatable mounting of the bearing journal 111a within the bearing opening O.

[0056] In the variant embodiment in FIG. 3, only a single sealing element in the form of a sealing bush 4 having a plurality of rows of sealing ridges 400 is provided in addition to the bearing bush 2. In the variant embodiment in FIG. 3, different geometries of sealing ridges 400 are illustrated here, tapering in an arrow or wedge shape in the direction of the bearing journal 111a and projecting into associated recesses 111.4 in order to define a labyrinth seal along the bearing journal 111a.

[0057] In addition to the sealing ridges 400 projecting into recesses 111.4, the sealing bush 4 in FIG. 3 also has at least one additional shortened radial sealing ridge 402 on its stem section 40. This shortened radial sealing ridge 402 lies opposite a shoulder 111.4a of the bearing journal 111.4. Consequently, the diameter of the bearing journal 111a is enlarged at this shoulder 111.4a, in particular relative to a recess 111.4 adjoining it along the longitudinal axis L. In this arrangement, the shortened radial sealing ridge 402 and the shoulder 111.4a are offset relative to one another by a step spacing a along the longitudinal axis L, with the result that the rims of the shortened radial sealing ridge 402 and of the shoulder 111.4a are not in alignment. A clearance extending along the longitudinal axis L and across the different sealing ridges 400 and 402 between the sealing bush 4 and the outer lateral surface of the bearing journal 111a thus winds several times by different amounts in opposite directions. The sealing action can thus be additionally enhanced by means of the additionally provided shortened radial sealing ridge 402 and the shoulder 111.4a.

[0058] In the variant embodiment in FIG. 4, the sealing bush 4 is formed without radially projecting sealing ridges on its stem section 40 and is thus provided more as a bearing bush. In this variant, the sealing action to avoid leakage flow is achieved more by means of a sealing washer 6, which is arranged in addition to the bearing bush 2 and the sealing bush 4 on the radially outer and inner ends of the bearing opening O and between the bushes 2 and 4. This sealing washer 6 (or sealing ring) is accommodated in a recess 111.4 of the bearing journal 111a in order thereby to make available a kind of labyrinth seal in this variant embodiment too.

[0059] In order to take account of a thermally induced expansion of the sealing washer 6 during operation, a narrow clearance g3 is provided between an inner lateral surface of the sealing washer 6 and the outer lateral surface of the bearing journal 111a, in the region of the recess 111.4.

[0060] To enable the sealing washer 6 to be mounted on the bearing journal 111a, the sealing washer 6 is also longitudinally slotted. In this case, a single longitudinal slot 601 once again has a nonlinear path, with the result that two circumferentially extending sections of the circumference 60a and 60b of the sealing washer 6, which are separated from one another by the slot 601, overlap one another axially and/or fit into one another. For this purpose, the profile of the slot 601 can be V-shaped in accordance with FIG. 4B, Z-shaped in accordance with FIG. 4C, -shaped in accordance with FIG. 4D or helical (around the longitudinal axis L) in accordance with FIG. 4E, for example. It is of course also possible here for the profiles of a slot 601 which are shown by way of example in FIGS. 4B, 4C, 4D and 4E to be provided for a slot 401 in a sealing bush 4 (or in the sealing bush 5) of the variant embodiments explained above.

[0061] In the present case, the sealing washer 6 is designed in such a way that the sealing washer 6 rests against and thus seals the inner wall or lateral surface 100 of the bearing opening O via its outer lateral surface under the conditions which arise during the operation of the engine T. Owing to the positioning on the recess 111.4 in the bearing journal 111a, there is an overlap with the sealing washer 6 when viewed in the axial direction, and this has a sealing effect, in particular a sealing effect under all (transient) thermal conditions. In this context, the longitudinally extending slot 601 is designed to compensate the thermal behavior and nevertheless to provide sealing in addition.

[0062] FIGS. 5A/5D, 5B/5E and 5C/5F illustrate further variant embodiments of a proposed stator vane assembly.

[0063] In the variant embodiment illustrated in FIGS. 5A and 5D, a sealing bush 5 having a plurality of rows of a radially extending sealing ridges 500 is arranged between the bearing bush 2 and a sealing bush 4 without radially extending sealing ridges, embodied as an additional bearing bush. This bearing bush 5 is of two-part design, having two bush halves for example, and is mounted in a recess 111.5 in the bearing journal 111a. In this case, the individual sealing ridges 500 extend radially inward in relation to the longitudinal axis L.

[0064] In the variant embodiment in FIGS. 5B and 5E, in contrast, a sealing bush 5 is arranged between bushes 2 and 4, in a recess 111.5 in the bearing journal 111a, and on this bush the plurality of rows of sealing ridges 500 extend radially outward. A labyrinth seal is thus defined in the region between the inner lateral surface 100 at the bearing opening O and the sealing ridges 500 of the sealing bush 5.

[0065] In the variant embodiment in FIGS. 5C and 5F, a sealing bush 4 is formed in a manner comparable to the variant embodiment in FIGS. 1A to 1C. Here, the sealing bush 4 comprises a plurality of rows of radially extending sealing ridges 400 on a stem section 40 extending from the bush rim 41 into the bearing opening O along the longitudinal axis L. In this case, the sealing bush 4 is in two parts.

[0066] FIGS. 6A and 6B show another variant embodiment of a two-part sealing bush 4, where the sections of the circumference 40a and 40b belonging to different bush halves or parts are separated from one another by a Z-shaped longitudinal slot 401 and adjoin one another in the assembled state. FIGS. 6A and 6B show the sealing bush 4 under two different thermal boundary conditions.

[0067] In a cold state corresponding to FIG. 6A, the mutually overlapping sections of the circumference 40a, 40b of the sealing bush 4 rest against one another or at least almost rest against one another in the region of a central (second) slot section 401b. This central slot section 401b forms a transition from a first slot section 401a and a third slot section 401c, which each extend substantially parallel to the longitudinal axis L.

[0068] At a relatively high temperature and thus under a relatively high thermal stress, the parts of the sealing bush 4 and thus the sections of the circumference 40a, 40b thereof expand in the circumferential direction. The slot sections 401a and 401c are thereby closed. In contrast, a (larger) clearance is formed between the mutually adjoining parts of the sealing bush 4 in the region of the central, obliquely extending slot section 401b. During the operation of the engine T, the slot 401 is thus closed (in a sealing manner) in the region of its slot sections 401a and 401b. Consequently, the multi-part sealing bush 4 in FIGS. 6A and 6B (and similarly also the sealing elements 4, 5 and 6 explained above) can be configured and designed in such a way that the slot 401 in the sealing bush 4 closes during the operation of the engine T as a result of the thermal expansion which occurs.

[0069] In the above-explained variant embodiments of stator vane assemblies, a leakage flow to the outside from the annular space RR along the bearing journal 111A, through the bearing opening O in the casing 1, is avoided in an effective manner by means of at least one bush-shaped or disk-shaped sealing element 4, 5, 6. In order to ensure low friction contact between the sealing element 4, 5 and/or 6which is subject to high thermal stresses during the operation of the engine T, on the one hand, and the outer lateral surface of the bearing journal 111a and/or the inner lateral surface 100 of the bearing opening O, on the other hand, the respective sealing element 4, 5, 6 can be produced, for example, from a plastics material with good sliding properties, e.g. a thermoplastic, polyamide, a polyamideimide, a polyimide, in each case either with or without graphite infiltration and with or without a PTFE component. Alternatively, the use of infiltrated graphite for the sealing elements with a relatively high usage temperature is also among the possible options.

LIST OF REFERENCE SIGNS

1 Casing

[0070] 10 Bearing extension
100 Inner lateral surface
10a Radially outer rim surface
10b Radially inner rim surface
11 Low-pressure compressor
110 Rotor blade
111 Stator vane

111.4 Recess

111.4a Shoulder

[0071] 111.5 recess
111a Bearing journal

111b Journal end

[0072] 12 High-pressure compressor
12a-12d Rotor blade row
13 High-pressure turbine
13a-13c Stator vane row
14 Medium-pressure turbine
15 Low-pressure turbine
2 Bearing bush/bearing washer
20 Adhesive surface
3 Adjusting device
30 Adjusting ring
31 Adjusting lever
4 Sealing bush (sealing element)
40 Stem section
400 Radial sealing ridge

401 Slot

[0073] 401a, 401b, Slot section
401c
402 (Shortened) radial sealing ridge
40a, 40b Section of the circumference
41 Bush rim (bearing section)
5 Sealing bush (sealing element)
500 Radial sealing ridge
6 Sealing washer (sealing element)

601 Slot

[0074] 60a, 60b Section of the circumference

A Outlet

[0075] A Step spacing
B Bypass duct
BK Combustor section
D Axis of rotation/spindle axis

E Inlet/Intake

F Fan

g1, g2, g3 Clearance

I Interior

[0076] L Longitudinal axis
M Central axis/axis of rotation
O Bearing opening
R Inlet opening
RR Annular space
T Gas turbine engine

TT Turbine

V Compressor