GB2355301A

GB2355301A - A wall structure for a combustor of a gas turbine engine

Info

Publication number: GB2355301A
Application number: GB9924120A
Authority: GB
Inventors: Michael Paul Spooner; Anthony Pidcock; Desmond Close
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1999-10-13
Filing date: 1999-10-13
Publication date: 2001-04-18
Also published as: GB9924120D0

Abstract

A wall structure (21, 22) for a combustor (20) of a gas turbine engine (10) comprises an outer wall (27) and an inner wall (28). The inner wall (28) comprises a plurality of wall elements, which may be in the form of tiles (29). A downstream path for the flow of a cooling fluid is defined in a space (30) between at least one of the wall elements and the outer wall (27), and an upstream path for the flow of the cooling fluid is defined in the space (30) between an adjacent downstream wall element and the outer wall (27). The upstream and downstream paths meet in the region of adjacent edges of the wall elements, and said wall structure (21, 22) further including means (36) at said adjacent edges for converting turbulent flow of said fluid to a more uniform flow.

Description

2355301 A Wall Structure For A Combustor Of A Gas Turbine Engine This

invention relates to wall structures for combustors of gas turbine engines. More particularly, invention relates to such wall structures comprising a plurality of wall elements.

Cooling air is used in combustors of gas turbine engines to prevent over heating. More air is required in the combustor to reduce emission of pollutants. Hence the air required for cooling is reduced, resulting in the need for the cooling air to be more efficient. This results in complex flow paths of the cooling air which increases component manufacturing costs.

one form of wall structure of combustors is formed from a plurality of tiles which employ heat removal features, such as pedestals or fins. These features allow cooling air to pick up heat from the tile prior to entering the combustion chamber as cooling films. However, these cooling features create turbulence in the air flow which can reduce the film cooling effectiveness of the air.

According to one aspect of this invention, there is provided a wall structure for a combustor of a gas turbine engine, the wall structure comprising an outer wall and an inner wall spaced from each other, the inner wall comprising a plurality of wall elements, each having opposite edges, wherein a downstream path for the flow of a cooling fluid is defined in the space between at least one of the wall elements and the outer wall, and an upstream path for the flow of the cooling fluid is defined in the space between an adjacent downstream wall element and the outer wall, said upstream and downstream paths meeting in the region of adjacent edges of the wall elements, and said wall structure further including means at said adjacent edges for converting turbulent flow of said cooling fluid to a more uniform flow.

2 Preferably, said conversion means is adapted to convert the turbulent flow to generally uniform flow.

Preferably, each of said wall elements defines upstream and downstream paths for the flow of cooling fluid.

Preferably, each of the wall elements further includes a base portion and a plurality of heat removal features extending from the base portion, said features being arranged in said paths for the flow of cooling fluids, the turbulent flow being created by the passage of said fluid around said features. Preferably, the features comprise pedestals to provide enhancement of heat transfer to the cooling fluid.

Preferably, the adjacent edges of the wall elements overlap each other.

The turbulent flow conversion means may comprise a path extension means extending beyond the region of meeting of the upstream and downstream paths.

The turbulent flow conversion means may comprise a first part provided on the downstream wall element, and a second part provided on the upstream wall element, the first and second parts being adapted to cooperate with each other in use to convert said fluid flow from a turbulent flow to a more uniform flow.

The turbulent flow conversion means may further include a plurality of spaced lands extending from one or both of the wall elements towards the other of said wall elements. In one embodiment, the first part of the flow conversion means comprises a plurality of spaced first lands extending from the upstream wall element towards the downstream wall element, and the second part comprises a plurality of second spaced lands extending from the downstream wall element towards the upstream wall element. The first and second lands are advantageously off- set relative to each other and preferably engage each other in the region between the upstream and downstream wall elements. The lands are preferably arranged at the region of meeting of the upstream or downstream paths. In this embodiment, the path extension 3 means comprises a lip extending from the upstream to beyond the adjacent edge of the downstream tile.

Conveniently, the first and second lands engage each other substantially mid-way between the upstream and 5 downstream wall elements.

In this embodiment, the first and second lands provide a plurality of staggered slots across adjacent edge regions of the wall elements.

In another embodiment, the turbulent flow conversion io means comprises flow reversal means to reverse the direction of flow of the cooling fluid from at least the upstream path. Preferably, the flow reversal means can reverse the flow of cooling fluid from the upstream path and the downstream path.

The flow reversal means is desirably adapted to reverse the flow of fluid in the downstream path and to allow the fluid in the upstream path to mix with fluid in the downstream path. The flow reversal means may be arranged to direct the mixed flow of cooling fluid in the downstream direction.

The flow reversal means may comprise an elongate member extending along one of the adjacent edges of the upstream and downstream wall elements. Preferably, the elongate member may include said path extension means which may comprise a curved surface to reverse the flow of said fluid. The curved surface preferably faces the downstream wall element. Conveniently, the elongate member is provided on the upstream wall element, and is preferably integrally formed on the upstream wall element, conveniently during manufacture, for example by casting of the wall element and the elongate member together. The path extension means may further include a first elongate lip extending along the opposite side of the second wall element to the outer wall. The first lip may extend beyond the edge of the downstream wall element.

Preferably, the elongate member has a second elongate lip extending between the downstream wall element and the 4 outer wall. The second lip may extend beyond the edge of the downstream wall element.

In a further embodiment, a plurality of spaced lands are provided between the downstream wall element and the second lip. Securing means, may be provided on the downstream wall element adjacent the edge, whereby the edge of the downstream wall element is held in position by the securing means, and the edge of the upstream wall element is supported by the spaced lands.

In another embodiment, a plurality of spaced further lands are provided between the second lip and the outer wall, and the second lip is clamped between the first mentioned lands and said further lands by the securing means. Thus, the elongate member constitutes the first part, and the first mentioned lands and/or the securing means may constitute the second part.

Securing means may be provided on both the upstream wall element and the downstream wall element adjacent the aforementioned respective edge to hold in position the adjacent edges of the upstream and downstream wall elements. Thus, this embodiment obviates the need for lands to clamp the second lip to hold the edges in position.

In another embodiment, the flow conversion means comprises a plurality of spaced lands on the upstream wall element. An engaging member may be provided on the flow conversion means to engage the edge of the downstream wall element. Preferably, the engaging member engages the edge of the downstream wall elements on the surface thereof facing the outer wall. Securing means is preferably provided on the downstream wall element adjacent the edge, whereby the edge of the downstream wall element is held in position by the engaging member and the securing means.

In this embodiment, the lands are shaped to create substantially uniform flow as close as possible to the lands.

Preferably, the lands are aero- dynamically shaped to direct said flow.

Preferably, the wall elements are in the form of tiles.

Embodiments of the invention will now be described by way of example only, with reference to the accompany drawings, in which:

Fig. 1 is a sectional side view of a part of a gas turbine engine; Fig. 2 is a sectional side view of a part of a combustor of the engine shown in Fig. 1; Fig. 3 is a schematic side view of parts of adjacent wall elements; Fig. 4 is a view along the lines IV-IV of Fig. 3; Figs. 5 to 7 are schematic side views of three variations of parts of adjacent wall elements; Fig. 8 is a schematic side view of a further variation of parts of adjacent wall elements; and.

Fig. 9 is a top plan view of part of the wall element shown in Fig. 8.

Referring to Fig. 1, a gas turbine engine is generally indicated at 10 and comprises, in axial flow series, an air intake 11, a propulsive fan 12, an intermediate pressure compressor 13, a high pressure compressor 14, combustion equipment 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 13 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 combustion equipment 15 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and 6 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 turbines 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 combustion equipment 15 is constituted by an annular combustor 20 having radially inner io and outer wall structures 21 and 22 respectively. The combustor 20 is mounted 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 combustor 20. The fuel nozzles 25 are circumferentiaily 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 combustor 20.

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 while functioning in a normal manner.

The inner and outer wall structures 21 and 22 are generally of the same construction and comprise an outer wall 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 adjacent or overlapping circumferentially extending edges 38 of adjacent tiles 29 overlap each other. Each tile 29 is provided with threaded studs 56 which project through apertures 58 in the outer wall 27. Nuts 60 are screwed onto the threaded studs 56 and tightened against the outer wall 27, thereby securing the tiles 29 in place. Alternative standard fixing arrangements can also be used.

7 The arrows in Fig. 1 and Y in Fig. 2 indicate the general direction of the flow of air through the engine 10 and the combustor 20.

Referring to Figs. 3 to 9 five different embodiments of two adjacent tiles 29 are shown. The tiles 29 are spaced from the outer wall 27 to define a space 30, such that cooling fluid, in the form of cooling air can flow through the space 30 between the tiles 29 and the outer wall 27. The cooling air enters the space 30 via ports (not shown) in the outer wall 27. On entering the space 30, the flow of cooling air is split into two paths. The first path is a downstream path 31A flowing in the same direction as the general direction of air flow through the engine. The second path is an upstream path 31B flowing in the opposite direction to the general flow of air through the engine. The air flowing along the paths mixes at adjacent or overlapping circumferential edges of adjacent tiles 29 and is directed along an inner surface 34 of the tiles 29 to effect cooling of the inner surface 34 of each tile 29. The surface 34 faces inwardly of the combustor 20.

In Figs. 3 to 8 there is shown two adjacent tiles 29A and 29B. Tile 29A is arranged upstream of tile 29B. Hence, the tiles 29A, 29B are respectively referred to herein as the upstream tile 29A and the downstream tile 29B. It will be appreciated that each of the tiles 29A and 29B defines upstream and downstream paths for the flow of air in their respective spaces 30. However, for the sake of clarity, the upstream path is not shown for the upstream tile 29A, and the downstream path is not shown for the downstream tile 29B.

Each of the tiles 29A, 29B is provided with a plurality of pedestals 32 which are provided to enhance the cooling effect of air in the space 30. The presence of the pedestals 32 creates turbulent flow of air through the space 30. As can be seen from Figs. 3 to 8, the flow of air exiting the upstream tile 29A passes across inner surface 34 of the downstream tile 29B. In order to ensure 8 that the turbulence of the flow of air across the inner surface 34 of the downstream tile is minimised, such that the flow is as uniform as possible, conversion means 36 are provided at the adjacent edges 38 of the upstream and downstream tiles 29A and 29B.

Referring to Fig. 3, the upstream tile 29A is provided with a lip 39 projecting beyond the adjacent edge of the downstream tile 29B.

A plurality of spaced lands 40 project from the edge of the downstream tile 29B in the direction away from the outer wall 27. At the position on the lip 39 aligned with the lands 40, there is provided a plurality of spaced lands 42 projecting towards the edge of the downstream tile 29B. The lands 40 projecting from the downstream tile 29B are off set from the lands 42 projecting from the upstream tile 29A and meet substantially mid-way from the upstream and downstream tiles 29A and 29B. Thus, a plurality of staggered slots 44, as shown in Fig. 4, is produced between the lands 40, 42.

The downstream flow of air (indicated by the arrow A) in the space defined by the upstream tile 29A meets the upstream flow of air (indicated by the arrow B) in the space defined by the downstream tile B. The meeting between these two flows of air occurs at the region adjacent the overlapping edges of the upstream and downstream tiles 29A and 29B. The subsequent flow of air, which is a mixture of the two flows in each of the two spaces, flows through the slots 44 defined by the lands 40, 42. Where the two f lows of air A, B meet, the flows are turbulent. As the air passes through the slots 44, the turbulent flow is converted to a uniform flow which passes over the lip 39. Thus, an effectively uniform flow is created over the hot surface 34 of the downstream tile 29B.

Referring to Fig. 5, the conversion means 36 comprises a curved member 46 integrally cast at the edge of the upstream tile 29A. The curved member 46 comprises an outwardly extending portion 48 extending from the downstream tile 29A towards the outer wall 27. A lip portion 50 extends from the 9 outwardly extending portion 48 towards the space between the downstream tile 29B and the outer wall 27. The lip portion extends beyond the edge of the downstream tile 29B and is engaged by a plurality of first lands 52 extending from the edge of the downstream tile 29B to the lip 50. A plurality of second lands 54 extend from the lip 50 to the outer wall 27 such that the lands 54 engage the outer wall 27.

Securing means in the form of a threaded stud 56A extends from the downstream tile 29B adjacent the edge region thereof. The stud 56A extends through an aperture 58A in the outer wall 25 and is secured in place by a nut 60A. Alternative fixing means can be used. Thus, the lip 50 is clamped between the lands 52, 54 by the stud 56A and nut 60A.

The flow of air indicated by the arrow A meets the flow of air indicated by the arrow B above the edge region of the downstream tile 29B. The mixed air, as shown by the arrow C passes through the lands 52 and is directed by a curved region 62 of the outwardly extending portion 48 towards the inner surface 34 of a downstream tile 29B. The turbulent flow at A and B is converted to a generally uniform flow C as the air passes over the curved region 62. The region 62 provides a smooth, unobstructed path for the flow C of air. The length of this path and the fact that it is smooth and unobstructed enables the turbulent flow of air to be sufficient to stabilise so that it is converted to a generally uniform flow.

Referring to Fig. 6, there is shown a modification to the design shown in Fig. 5 but differs in that the lands 52, 54 are obviated and further the securing means in the form of a further stud 56B is provided adjacent the downstream edge region of the upstream tile 29B. The stud 56B projects through an aperture 58B and has threaded thereon a further nut 60B. Thus the upstream edge of the downstream tile 29B is held in place by the stud 56A and nut 60A arrangement, and 3 similarly, the downstream edge of the upstream tile 29B is held in place by the stud 56B and nut 60B arrangement.

Referring to Fig. 7. there is shown a further variation on the structure shown in Figs. 5 and 6 which again possesses only one stud 56A and nut arrangement 60A but, with this variation, the lands 54 extending from the lip 50 to the 5 outer wall 27 are not present. Instead, the upstream tile 29B is held by the action of the lands 52 extending from the upstream edge of the downstream tile 29B to engage the lip 50, and the nut 60A tightened onto the stud 56A against the outer wall 27. The length of the region 62 in both embodiments shown in Figs. 6 and 7 and the fact that it is smooth and unobstructed acts to stabilise the flow of air to a generally uniform flow in the same way as described with reference to Fig. 5.

In each of the variations shown in Figs. 5 to 7, the length of the curved region 62 of the curved member 46 beyond the edge of the upstream edge of the downstream tile 29B is substantially the same as the length of the lip 38 as shown in the embodiment in Fig. 3.

Referring to Figs. 8 and 9, there is shown a variation of the embodiment shown in Figs. 3 and 4, wherein instead of lands 40 and 42, extending respectively from the downstream and upstream tiles 29B and 29A, there is provided a plurality of lands 70 extending from the upstream tile 29A.

The lands 70 are aerodynamically configured, such as to be the shape of, for example, a fin so as to direct the turbulent air flowing in the direction indicated by the arrows A around the lands 70 such that the air exits from the lands 70 in a uniform manner directly behind the lands 70 as shown by the arrow C. Thus, substantially linear cooling air flows over the lip 38.

An engagement member 72 is provided on the lands 70 and includes a downstream tile engaging portion 74 to engage the upstream edge of the downstream tile 27B. Thus, the downstream edge of the upstream tile 27A is held between the engaging portion 74 and the action of the stud 56 and nut 60 arrangement on the downstream tile 29B.

I I Various modifications can be made without departing from the scope of the invention.

12

Claims

1. A wall structure for a combustor of a gas turbine engine, the wall structure comprising an outer wall and an inner wall spaced from each other, the inner wall comprising a plurality of wall elements, each having opposite edges, wherein a downstream path for the flow of a cooling fluid is defined in the space between at least one of the wall elements and the outer wall, and an upstream path for the flow of the cooling fluid is defined in the space between an adjacent downstream wall element and the outer wall, said upstream and downstream paths meeting in the region of adjacent edges of the wall elements, and said wall structure further including means at said adjacent edges for converting turbulent flow of said cooling fluid to a more uniform flow.

2. A wall structure according to claim 1 wherein the flow conversion means comprises a path extension means extending beyond the region at which the upstream and downstream paths meet.

3. A wall structure according to claim 1 or 2 wherein the flow conversion means comprises a plurality of spaced lands extending from one or both of the wall elements towards the other of said wall elements, the lands being arranged adjacent the region at which the upstream and downstream paths meet.

4. A wall or structure according to claim 1 or 2 wherein the flow conversion means comprises a first part provided on the downstream wall element and a second part provided on the upstream wall elements, the first and second parts being adapted to cooperate with each other to provide said conversion of turbulent flow to more uniform flow.

5. A wall structure according to claim 4 wherein the first part of the flow conversion means comprises a plurality of spaced first lands extending from the upstream wall element towards the downstream wall element, and the second part 13 comprises a plurality of second spaced lands extending from the downstream wall element towards the upstream wall element.

6. A wall structure according to claim 5 wherein the first 5 and second lands are off-set relative to each other and meet in the region between the upstream and downstream wall elements.

7. A wall structure according to claim 6 wherein the first and second lands engage each other substantially mid-way io between the upstream and downstream wall elements.

8. A wall structure according to claim 5, 6 or 7 wherein the first and second lands provide a plurality of staggered slots across the adjacent edges of the wall elements.

9. A wall structure according to any of claims 4 to 8 including a lip extending from the upstream wall element substantially parallel to the downstream wall element beyond the adjacent edge of the downstream wall element.

10. A wall structure according to claim 1, 2 or 4 wherein the turbulent flow conversion means comprises flow reversal means to reverse the direction of flow of the cooling fluid from at least the upstream path.

11. A wall structure according to claim 10 wherein the flow reversal means is adapted to reverse the flow of cooling fluid from both the upstream path and the downstream path.

12. A wall structure according to claim 11 wherein the flow reversal means is adapted to reverse the flow of fluid in the downstream path and to allow the fluid in the upstream path to mix with fluid in the downstream path, the flow reversal means being arranged to direct the mixed flow of cooling fluid in the downstream direction.

13. A wall structure according to claim 9, 10 or 11 or 12 wherein the flow reversal means comprises an elongate member extending along one of the adjacent edges of the upstream and downstream wall elements, the elongate member including said path extension means which comprises a curved surface to reverse the flow of said fluid, the curved surface facing the 14 downstream wall element.

14. A wall structure according to claim 13 wherein the elongate member is integrally formed on the upstream wall element.

15. A wall structure according to claim 13 or 14 wherein the elongate member has a first elongate lip extending along the opposite side of the downstream wall element to the outer wall, and a second elongate lip extending between the downstream wall element and the outer wall.

io

16. A wall structure according to claim 15 wherein the second lip extends beyond the edge of the downstream wall element, a plurality of spaced lands are provided between the downstream wall element and the second lip, and securing means is provided adjacent the edge of the downstream wall element, whereby the edge of the downstream wall element is held in position by the securing means, and the edge of the upstream wall element is supported by the spaced lands.

17. A wall structure according to claim 16 wherein a plurality of spaced further lands are provided between the second lip and the outer wall, whereby the second lip is clamped between the first mentioned lands and said further lands by the securing means.

18. A wall structure according to claim 15 wherein securing means is provided on both the upstream wall element and the downstream wall element adjacent the edges to hold in position said edges of the upstream and downstream wall elements.

19. A wall structure according to claim 1 wherein the flow conversion means comprises a plurality of spaced lands on the upstream wall element, an engaging member be' ,0 ing provided on the flow conversion means to engage the edge of the downstream wall element.

20. A wall structure according to claim 19 wherein the engaging member engages the edge of the downstream wall 35 elements on the surface thereof facing the outer wall.

21. A wall structure according to claim 19 or 20 wherein the securing means is provided on the downstream wall element adjacent the edge, whereby the edge of the downstream wall element is held in position by the engaging member and the securing means.

22. A wall structure according to claim 19, 20 or 21 wherein the lands are shaped to create substantially uniform flow as close as possible to the lands.

23. A wall structure substantially as herein described with reference to any of Figs. 3 to 9 of the accompanying 10 drawings.

24. 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.