GB2356042A

GB2356042A - Improvements in or relating to wall elements for gas turbine engines

Info

Publication number: GB2356042A
Application number: GB9926260A
Authority: GB
Inventors: Michael Paul Spooner; Anthony Pidcock; Desmond Close
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1999-11-06
Filing date: 1999-11-06
Publication date: 2001-05-09
Also published as: GB9926260D0

Abstract

A wall element (29) for a wall structure (21 or 22, fig.2) of a combustor (20) in a gas turbine engine (10) comprises a base portion (36) and a barrier member (44) extending at least part way across the base portion (36), the barrier member (44) serving to control the flow (A) of a cooling fluid across the base portion (36).

Description

2356042 Wall Elements For Gas Turbine Engine Combustors This invention

relates to combustors for gas turbine 5 engines and in particular to walleelements for use in wall structures of gas turbine engine combustors.

It is known to use tiles to form the wall structure of combustors in gas turbine engines. Cooling air is used to prevent overheating of these tiles. The main heat removal mechanisms are jet impingement on the tile and turbulent convection induced by, for example, fins and pedestals.

In previously proposed tiles, the cooling air is split into upstream and downstream paths which respectively cool different areas of the tile. It is a disadvantage of such tiles that relative cooling performance can vary in different regions of the tile.

According to one aspect of this invention there is provided a wall element for a wall structure of a gas turbine engine combustor, the wall element comprising a base portion and a barrier member extending across the base portion, wherein at least part of the barrier member is spaced from an edge of the base portion, the barrier member serving in use to control the flow of a cooling fluid across said base portion. 25 Preferably, the barrier member is configured such that cooling fluid passing over the base portion of the wall element on one side of the barrier member in use is directed away from the barrier member on said one side. In one embodiment, the barrier member is configured such that, in use, cooling fluid passing over the base portion on first and second opposite sides of the barrier member is directed in first and second opposite directions away f rom. said barrier member.

Preferably, the barrier member is constructed such that cooling fluid passing over the base portion on one side thereof is prevented from passing over the barrier member to 2 the other side. Preferably, the first and second sides of the barrier member are isolated from each other.

Preferably, the wall structure of which the wall element is adapted to form a part has an axis which, in use, extends substantially parallel to the principal axis of the engine, and in one embodiment, the barrier member extends transverse to said axis of the wall structure. The barrier member preferably extends substantially perpendicular to said axis of the wall structure. In another embodiment, the barrier member extends substantially parallel to said axis of the wall structure.

The barrier member may extend substantially wholly across the base portion.

The wall element may be provided with a plurality of barrier members defining a boundary of a region for the flow of a cooling fluid isolated from the remainder of the wall element and resulting in increased or decreased pressure of said cooling fluid in said region relative to the remainder of said wall element. 20 The barrier members may each be axially extending barrier members or may each be transversely extending barrier members. Preferably, said plurality of barrier members includes at least one axially extending barrier member and at least one transversely extending barrier member. Each of the plurality of barrier members may engage or abut each adjacent barrier member to define said region.

The, or each, barrier member may be in the form of an elongate bar which may extend substantially from said base portion to said outer wall.

The base portion may be provided with a plurality of heat removal members which may comprise heat removal pedestals. The base portion may define at least one effusion cooling hole.

The wall element is preferably in the form of a tile.

According to another aspect of this invention there i' s 3 provided a wall structure for a gas turbine engine combustor comprising an inner wall and an outer wall, the inner wall comprising a plurality of wall elements as described above.

The outer wall may be provided with fluid supply means for supplying cooling fluid to at least one side of a barrier member. The fluid supply means preferably comprises at least one hole defined in the outer wall.

The outer wall may be provided with first and second fluid supply means for supplying cooling fluid respectively to opposite sides of a barrier member. In one embodiment, the first fluid supply means may comprise at least one hole defined in the outer wall for supplying cooling fluid to one side of the barrier member and the second fluid supply means comprises at least one hole defined by the outer wall for supplying cooling fluid to the other side of the barrier members.

In another embodiment, where the wall element comprises a plurality of said barrier members defining a plurality of regions on the base portion, and the outer wall is provided with a plurality of fluid supply means to supply fluid to a plurality of said regions, whereby each of said regions supplied has a separate supply of said cooling fluid.

Embodiments of the invention will now be described by way of example only with reference to the accompanying diagrammatic drawings, in which:- Fig. 1 is a sectional side view of the upper half of a gas turbine engine; Fig. 2 is a vertical cross-section through the combustor of the gas turbine engine shown in Fig. 1; Fig. 3 is a sectional side view of a first embodiment of a wall structure showing a wall element; Fig. 4 is a sectional side view of a further embodiment of a wall structure showing a further wall element; Fig. 5 is a perspective view of part of the wall element shown in Fig. 3; Fig. 6 is a perspective view of part of a f urther wall 4 element; Fig. 7 is a perspective view of part of another wall element.

Referring to Fig. 1, a ducted gas turbine engine is generally indicated at 10 and has a principal axis X-X. The engine 10 comprises, in axial flow series, an air intake 11, propulsive fan 12, an intermediate pressure compressor 13, high pressure compressor 14, combustor 15, a high pressure turbine 16, an intermediate pressure turbine 17, a low pressure turbine 18 and an exhaust nozzle 19.

The gas turbine engine 10 works in a conventional manner so that air entering the intake 11 is accelerated by the fan 12 which produce two air flows: a first air flow into the intermediate pressure compressor 13 and a second air flow which provides propulsive thrust. The intermediate pressure compressor compresses the air flow directed into it before delivering that air to the high pressure compressor 14 where further compression takes place.

The compressed air exhausted from the high pressure compressor 14 is directed into the combustor 15 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 16, 17 and 18 before being exhausted through the nozzle 19 to provide additional propulsive thrust. The high, intermediate and low pressure turbine 16, 17 and 18 respectively drive the high and intermediate pressure compressors 14 and 13, and the fan 12 by suitable interconnecting shafts.

Referring to Fig. 2, the combustor 15 is constituted by 0 an annular combustion chamber 20 having radially inner and outer wall structures 21 and 22 respectively. The combustor 20 is secured to a wall 23 by a plurality of pins 24 (only one of which is shown). Fuel is directed into the combustor 20 through a number of fuel nozzles 25 (only one of which is shown) located at the upstream end 26 of the chamber 15. The fuel nozzles 25 are circumferentially spaced around the engine 10 and serve to spray fuel into air derived from the high pressure compressor 14. The resultant fuel/air mixture is then combusted within the chamber 15.

The combustion process which takes place generates a large amount of heat. It is therefore necessary to arrange that the inner and outer wall structures 21 and 22 are capable of withstanding this heat.

The inner and outer wall structures 21 and 22 are generally of the same construction and comprise an outer wall io 27 and an inner wall 28. The inner wall 28 is made up of a plurality of discrete wall elements in the form of tiles 29, which are all of the same general rectangular configuration and are positioned adjacent each other. The circumferentially extending edges 30, 31 of adjacent tiles overlap each other. Each tile 29 is provided with threaded studs 32 which project through apertures in the outer wall 27. Nuts 34 are screwed onto the threaded studs 32 and tightened against the outer wall 27, thereby securing the tiles 29 in place.

Referring to Figs. 3 to 7, there are shown different embodiments of tiles 29. Each tile 29 comprises a base portion 36 and a plurality of heat removal features in the form of upstanding pedestals 38 extending from the base portion 36 towards the outer wall 27.

The outer wall 27 is provided with a plurality of effusion holes 40 to permit the ingress of air into the space 42 between the base portion 36 of the tile 29 and the outer wall 27. The arrows A in Figs. 3 and 4 indicate the direction of air flow across the tiles from the effusion )0 holes 40.

Each of the tiles 29 is provided with at least one barrier member 44 in the form of an elongate bar extending across the base portion 36.

Figs. 3 shows a section of the wall structure 21 parallel to the principal axis of the engine 10. Reference is also made to Fig. 5 which shows the tile 29 of Fig. 3.

6 The tile 29 shown in figs. 3 and 5 has a circumferentially extending barrier member 44. The barrier member 44 extends wholly across the base portion 36. As seen in Fig. 3, the barrier member 44 extends from the base portion 36 5 substantially to the outer wall 27.

As shown in Fig. 3, the effusion holes 40 are provided in the outer wall 27 on either side of the barrier member 44. Thus cooling air entering the space 42 via the effusion holes 40 is directed by the barrier member 44 in opposite directions away from the barrier member 44 as shown by the arrows A. The cooling air in the space 42 then follows upstream and downstream paths across the tile 29 to exit therefrom at opposite circumferentially extending edges.

one effusion hole 40 is provided on each side of the barrier member 44. This provides a separate supply of cooling air through the outer wall 27 for the respective regions on either side of the barrier member 44.

If desired, the tile 29 may be provided centrally with effusion holes 46 to direct air, as shown by the arrows B, into the combustor 20 to supplement the air film cooling the surface 47 of the base portion 36 of the tile 29.

Referring to Fig. 5 a lip 48 extends along the one of the axially extending edges 50 of the tile 29. A similar lip is also provided at the opposite axially extending edge but for reasons of clarity, only one axial edge 50 is shown, and hence, only one lip 48.

Fig. 4 shows a variation of the tile as shown in Fig. 3, in which two circumferentially extending barrier members 44A, 44B are provided. With the embodiment shown in Fig. 4, the outer wall 27 is provided with effusion holes 40 on opposite sides of the barrier members 44A, 44B, whereby cooling air is directed in the upstream and downstream directions, in a similar manner to that shown in Fig. 3.

The outer wall 27 is also provided with further effusion holes 52 arranged to direct cooling air into the region defined between the barrier members 44A, 44B. The cooling 7 air travelling into the region between the barrier members 44A, 44B is directed through effusion holes 46, as shown by the arrows B, to supplement the cooling air passing across the inner surface 47 of the tile 29. By providing two barrier members 44A and 44B, the pressure drop across the effusion holes 46 is somewhat less than with the embodiment shown in Fig. 3.

The tile 29 shown in Fig. 4 thus comprises three regions, the first being to the left of the barrier member 44A, the second being to the right of the barrier member 44B, and the third being between the barrier members 44A and 44B.

Each of these regions is provided with a separate supply of cooling air through the outer wall 28. The effusion holes 40 respectively supply cooling air to the first region to the left of barrier member 44A and to the second region to the right of barrier member 44B. The effusion holes 52 supply cooling air to the third region between the barrier members 44A and 44B.

Referring to Fig. 6 there is shown a further embodiment of the tile 29 having a barrier member 44 extending in a direction which would be parallel to the principal axis of the engine 10. Thus, cooling air is directed axially across the tile 29, and is contianed circumferentially of the tile into pre-defined flow regions.

Fig. 7 shows a further embodiment of the invention comprising first and second axially extending barrier members 44A, 44B and a transversely extending barrier member 44C, the barrier members 44A, 44B and 44C being arranged in engagement with each other to define a region 52 into which cooling air 0 can be directed through effusion holes (not shown) in the outer wall 27. The embodiment shown in Fig. 7 is particularly useful in the event that a particular region of a tile 29 suffers significantly from overheating. Further effusion holes (not shown) are provided in the base portion 36 to direct air from the region 52 through the base portion 36 to supplement the cooling film passing across the inner 8 surface of the tile 29. The concentration of the cooling air in the region 52 by the barrier members 44A, 44B and 44C results in the pressure drop across the base portion 36 being less than for the remainder of the tile 29.

The use of the barrier members 44 is advantageous in the embodiment shown, because it enables the flow of cooling air into the space 42 to be split in a controlled manner. In addition, this control of the cooling air flow split is independent of the feed hole position, because the cooling air cannot pass over the barrier members 44. By the use of axially and circumferentially extending barrier members 44, it is possible to have independent control of pressure drop across different regions of the tile defined by the barrier members 44. Consequently, optimum heat removal and air flow rates can be achieved over the surface area of the tile.

In addition, the barrier members 44 can be provided to define areas of the base portion 36 with differing cooling requirements. For example, pedestals 38 and/or effusion holes 46 could be provided on one side of a barrier member 44 and the other side may be provided with no pedestals 38 or effusion holes 46. In another example, effusion holes 46, but no pedestals 38, could be provided on one side of a barrier member 44, whereas pedestals. 38, but no effusion holes 46, could be provided on the other side.

Various modifications can be made without departing from the scope of the invention. For example, although tile embodiments described above comprise heat removal pedestals 38 extending from the base portion 36, the barrier members 44 can also be used beneficially with tiles 29 which do not include such pedestals. Similarly, the barrier members 44 can be used with tiles 29 which do not possess effusion holes 465 in the base portion 36.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable 9 feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A wall element for a wall structure of a gas turbine engine combustor, the wall element comprising a base portion and a barrier member extending across the base portion wherein at least part of the barrier member is spaced from an edge of the base portion, the barrier member serving in use to control the flow of a cooling fluid across said base portion.

2. A wall element according to claim 1 wherein the barrier member is configured such that, in use, cooling fluid passing over the base portion on one side of the barrier member is directed away from the barrier member on said one side.

3. A wall element according to claim 1 or 2 wherein the 15 barrier member is configured such that, in use, cooling fluid passing over the base portion on first and second opposite sides of the barrier member is directed in first and second opposite directions away from said barrier member.

4. A wall element according to claim 1, 2 or 3 wherein the 20 barrier member is constructed such that cooling fluid passing over the base portion on one side thereof is prevented from passing over the barrier member to the other side, the first and second sides of the barrier member thereby being isolated from each other.

5. A wall element according to any preceding claim wherein the wall structure of which the wall element is adapted to form a part has an axis which, in use, extends substantially parallel to the principal axis of the engine, at least part of the barrier member, extending transverse to said axis of the wall structure.

6. A wall element according to claim 5 wherein the barrier member extends substantially perpendicularly to said axis of the wall structure.

7. A wall element according to any preceding claim wherein 35 the wall structure of which the wall element is adapted to form a part has an axis which, in use, extends substantially parallel to the principal axis of the engine, at least part of the barrier member extending substantially parallel to said axis.

8. A wall element according to claim 5, 6 or 7 including a 5 plurality of said barrier members defining therebetween a region for the flow of cooling fluid isolated from the remainder of the wall element and resulting in increased or decreased pressure of said cooling fluid in said region relative to the remainder of said wall element.

9. A wall element according to claim 8 wherein the barrier members are each axially extending barrier members.

10. A wall element according to claim 8 wherein the barrier members are each transversely extending barrier members.

11. A wall element according to claim 8, 9 or 10 wherein the 15 barrier member extends substantially wholly across the base portion.

12. A wall element according to claim 8 wherein said plurality of barrier members comprise at least one axially extending barrier member and at least one transversely extnding barrier member, each engaging or abutting an adjacent barrier member to define said region.

13. A wall element according to any preceding claim wherein the base portion is provided with a plurality of heat removal members.

14. A wall element according to claim 13 wherein the heat removal members comprise heat removal pedestals.

15. A wall element according to any preceding claim wherein the base portion defines at least one effusion cooling hole.

16. A wall element according to any preceding claim in the 0 form of a tile.

17. A wall element substantially as herein described with reference to Figs. 3 to 7 of the accompanying drawings.

18. A wall structure for a gas turbine engine combustor comprising an inner wall and outer wall, the inner wall 3 comprising a plurality of wall elements according to any preceding claim.

12

19. A wall structure according to claim 18 wherein the outer wall is provided with fluid supply means for supplying cooling fluid to one side of a barrier member.

20. A wall structure according to claim 19 wherein the fluid supply means comprises at least one hole defined in the outer wall.

21. A wall stucture according to claim 18 wherein the outer wall is provided with first and second fluid supply means for supplying cooling fluid respectively to opposite sides of a barrier member.

22. A wall structure according to claim 21 wherein the first fluid supply means comprises at least one hole defined by the outer wail for supplying cooling fluid to one side of the barrier member and the second fluid supply means comprises at least one hole defined by the outer wall for supplying cooling fluid to the other side of the barrier member.

23. A wall structure according to any of claims 18 wherein the wall element comprises a plurality of said barrier members defining a plurality of regions on the base portion and the outer wall is provided with a plurality of fluid supply means to supply fluid to a plurality of said regions, whereby each of said regions supplied has a separate supply of said cooling fluid.

24. A gas turbine engine combustor comprising a wall structure as claimed in any of claims 16 to 23.

25. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.