EP3255344B1

EP3255344B1 - A combustion chamber

Info

Publication number: EP3255344B1
Application number: EP17171658.2A
Authority: EP
Inventors: Imon-Kalyan Bagchi; Neil GATER; Thulasiram EZHILAN; Marek MACHEJ
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2016-06-10
Filing date: 2017-05-18
Publication date: 2019-02-06
Anticipated expiration: 2037-05-18
Also published as: EP3255344A1; GB201610122D0; US20170356653A1

Description

The present disclosure relates to a combustion chamber and in particular to a gas turbine engine combustion chamber.
One known type of combustion chamber comprises one or more walls each of which comprises a double, or dual, wall structure. A dual wall structure comprises an annular outer wall and an annular inner wall spaced radially from the annular outer wall by rails to define a chamber. The annular outer wall has a plurality of impingement apertures to supply coolant into the chamber and the annular inner wall has a plurality of effusion apertures to supply coolant from the chamber over an inner surface of the annular inner wall to provide a film of coolant on the inner surface of the annular inner wall. Such a known combustion chamber is disclosed in US 2009/293488 A1 .
The annular inner wall comprises a plurality of rows of circumferentially arranged tiles. These rows of tiles produce a discontinuity, or a number of discontinuities, in the inner surface of the annular inner wall that has a detrimental effect on the film of coolant on the inner surface of the annular inner wall. The downstream ends of the tiles have lips which extend axially towards but are spaced from the upstream ends of the adjacent row of tiles and the annular outer wall has one or more rows of apertures to direct coolant onto the lips and then to assist in reforming a film of coolant over the inner surface of the upstream ends of the adjacent row of tiles.
The row or rows of apertures in the annular outer wall which direct coolant onto the lips of the tiles reduce the strength of the annular outer wall and it is possible for cracks to initiate and propagate circumferentially around the annular outer wall. The problem is exacerbated by the rails at the downstream ends of the tiles which are positioned close to the row of rows of apertures in the annular outer wall because the rails conduct heat from the tiles to the annular outer wall. At the points where the fasteners, studs, used to secure the tiles to the annular outer wall are close to the rails the clamping loads due to the fasteners produces perfect conduction of heat from the tiles through the rails to the annular outer wall and hence increasing the stress in the annular outer wall adjacent the row or rows of apertures in the annular outer wall which direct coolant onto the lips of the tiles. The annular outer wall may have a bend and the bend may be subject to significant thermal and vibrational stresses. If the bend is positioned close to the row or rows of apertures in the annular outer wall then this may further increase the stress in the annular outer wall adjacent the row or rows of apertures in the annular outer wall which direct coolant onto the lips of the tiles.
Hence, this may lead to a reduction in the working life of the annular outer wall of the combustion chamber.
Accordingly the present disclosure seeks to provide a combustion chamber which reduces, or overcomes, the above mentioned problem.
According to a first aspect of the present disclosure there is provided a combustion chamber arrangement comprising an annular outer wall and an annular inner wall spaced from the annular outer wall, the annular inner wall comprising at least one row of tiles, each row of tiles comprising a plurality of circumferentially arranged tiles, the downstream end of each tile in the at least one row of tiles having a rail extending from the downstream end of the tile towards and sealing with an inner surface of the annular outer wall and a lip extending in a downstream direction from the downstream end of the tile, the annular outer wall having at least one row of apertures to direct coolant onto the outer surfaces of the lips at the downstream ends of the tiles in the at least one row of tiles, each tile in the at least one row of tiles having at least one fastener positioned upstream of the rail, the at least one fastener of each tile in the at least one row of tiles extending from the tile and through a corresponding mounting aperture in the annular outer wall to secure the tile to the annular outer wall, the rail of at least one tile defining at least one slot with the inner surface of the annular outer wall, the at least one slot of the at least one tile being arranged in a region downstream of the at least one fastener and none of the apertures in the at least one row of apertures in the annular outer wall being arranged in the region downstream of the at least one fastener of the at least one tile.
The rail of the at least one tile may define a plurality of slots with the inner surface of the annular outer wall and the plurality of slots of the at least one tile being arranged in the region downstream of the at least one fastener.
The rail of each tile may define at least one slot with the inner surface of the annular outer wall, the at least one slot of each tile being arranged in a region downstream of the at least one fastener and none of the apertures in the at least one row of apertures being arranged in the region downstream of the at least one fastener of each tile.
The rail of each tile may define a plurality of slots with the inner surface of the annular outer wall and the plurality of slots of each tile being arranged in the region downstream of the at least one fastener.
Each tile in the at least one row of tiles may have a plurality of fasteners positioned upstream of the rail, each fastener extending from the tile and through a corresponding mounting aperture in the annular outer wall to secure the tile to the annular outer wall.
The rail of each tile in the at least one row of tiles may define a plurality of slots with the inner surface of the annular outer wall, at least one slot of each tile being arranged in a region downstream of each fastener and none of the apertures in the at least one row of apertures in the annular outer wall being arranged in the region downstream of each fastener of each tile.
A plurality of slots of each tile may be arranged in a region downstream of each fastener.
The annular inner wall may comprise an upstream row of tiles and a downstream row of tiles, the downstream end of each tile in the upstream row of tiles having a lip extending in a downstream direction towards but spaced from the upstream ends of the tiles in the downstream row of tiles, the annular outer wall having at least one row of apertures to direct coolant onto the outer surfaces of the lips at the downstream ends of the tiles in the upstream row of tiles, each tile in the upstream row of tiles having at least one fastener positioned upstream of the rail, the at least one fastener of each tile in the upstream row of tiles extending from the tile and through a corresponding mounting aperture in the annular outer wall to secure the tile to the annular outer wall, the rail of at least one tile defining at least one slot with the inner surface of the annular outer wall, the at least one slot of the at least one tile being arranged in a region downstream of the at least one fastener and none of the apertures in the at least one row of apertures in the annular outer wall being arranged in the region downstream of the at least one fastener of the at least one tile.
Each tile in the upstream row of tiles may have a plurality of fasteners positioned upstream of the rail, each fastener extending from the tile and through a corresponding mounting aperture in the annular outer wall to secure the tile to the annular outer wall.
The annular outer wall may have a bend, the rail at the downstream end of each tile in the upstream row of tiles being arranged upstream of the bend in the annular outer wall.
The at least one row of apertures in the annular outer wall may be arranged upstream of the bend in the annular outer wall and downstream of the rail at the downstream end of each tile in the upstream row of tiles.
The at least one row of apertures in the annular outer wall may be arranged downstream of the bend in the annular outer wall and downstream of the rail at the downstream end of each tile in the upstream row of tiles.
The upstream end of each tile in the downstream row of tiles may have a rail extending from the upstream end of the tile towards and sealing with an inner surface of the annular outer wall.
The rail at the upstream end of each tile in the downstream row of tiles may extend in an upstream direction.
The rail at the upstream end of each tile in the downstream row of tiles may be arranged downstream of the bend in the annular outer wall.
The annular outer wall may have a bend, the rail at the downstream end of each tile in the at least one row of tiles being arranged upstream of the bend in the annular outer wall.
The at least one row of apertures in the annular outer wall may be arranged upstream of the bend in the annular outer wall and downstream of the rail at the downstream end of each tile in the at least one row of tiles.
The at least one slot in the rail of the at least one tile may be arranged perpendicular to the surface of the rail or at angle to the surface of the rail.
A plurality of slots may be arranged in a region downstream of the at least one fastener, the region downstream of the at least one fastener having a circumferential dimension of up to four times the diameter of the at least one fastener.
At least one slot may be arranged in a region downstream of the at least one fastener, the region downstream of the at least one fastener having a circumferential dimension of up to four times the diameter of the at least one fastener.
The annular outer wall may not have any apertures arranged in a region downstream of the at least one fastener, the region downstream of the at least one fastener having a circumferential dimension of up to four times the diameter of the at least one fastener. The annular outer wall may be imperforate in the region downstream of the at least one fastener, the region downstream of the at least one fastener having a circumferential dimension of up to four times the diameter of the at least one fastener.
The annular outer wall may not have any apertures arranged in a region downstream of the at least one fastener, the region downstream of the at least one fastener having a circumferential dimension of up to twice the diameter of the at least one fastener. The annular outer wall may be imperforate in the region downstream of the at least one fastener, the region downstream of the at least one fastener having a circumferential dimension of up to twice the diameter of the at least one fastener.
The combustion chamber may be an annular combustion chamber, the annular combustion chamber comprising a radially inner annular wall structure, a radially outer annular wall structure and an upstream end wall structure, the radially outer annular wall structure comprising the annular inner wall and the annular outer wall and the annular inner wall is spaced radially inwardly from the annular outer wall.
The combustion chamber may be an annular combustion chamber, the annular combustion chamber comprising a radially inner annular wall structure, a radially outer annular wall structure and an upstream end wall structure, the radially inner annular wall structure comprising the annular inner wall and the annular outer wall and the annular inner wall is spaced radially outwardly from the annular outer wall.
The combustion chamber may be a tubular combustion chamber and the annular inner wall is spaced radially inwardly from the annular outer wall.
The combustion chamber may be a gas turbine engine combustion chamber.
The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects of the invention may be applied mutatis mutandis to any other aspect of the invention.
Embodiments of the invention will now be described by way of example only, with reference to the Figures, in which:

Figure 1 is a sectional side view of a turbofan gas turbine engine having a combustion chamber arrangement according to the present disclosure.
Figure 2 is an enlarged cross-sectional view of a combustion chamber arrangement according to the present disclosure.
Figure 3 is a further enlarged cross-sectional view of a portion of a combustion chamber arrangement according to the present disclosure.
Figure 4 is an enlarged perspective view of the portion of the combustion chamber arrangement shown in Figure 3.
Figure 5 is a further enlarged perspective view of a portion of the downstream end of a tile used in a combustion chamber arrangement according to the present disclosure.
Figure 6 is a plan view in the direction of arrow A in Figure 3 showing a portion of the downstream end of a tile and the surrounding outer wall used in a combustion chamber arrangement according to the present disclosure.

With reference to Figure 1, a turbofan gas turbine engine is generally indicated at 10, having a principal and rotational axis X. The engine 10 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. A nacelle 21 generally surrounds the engine 10 and defines the intake 11, a bypass duct 22 and a bypass exhaust nozzle 23.
The gas turbine engine 10 works in the conventional manner so that air entering the intake 11 is compressed by the fan 12 to produce two air flows: a first air flow A into the intermediate pressure compressor 13 and a second air flow B which passes through a bypass duct 22 to provide 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 thereby drive the high, intermediate and low- pressure turbines 16, 17, 18 before being exhausted through the nozzle 19 to provide additional propulsive thrust. The high 16, intermediate 17 and low 18 pressure turbines drive respectively the high pressure compressor 14, intermediate pressure compressor 13 and fan 12, each by suitable interconnecting shaft 24, 25 and 26 respectively.
Combustion equipment 15 according to the present disclosure, as shown more clearly in figures 2 to 6, comprises an annular combustion chamber arrangement and comprises a radially inner annular wall structure 40, a radially outer annular wall structure 42 and an upstream end wall structure 44. The radially inner annular wall structure 40 comprises a first annular wall 46 and a second annular wall 48. The radially outer annular wall structure 42 comprises a third annular wall 50 and a fourth annular wall 52. The second annular wall 48 is spaced radially from and is arranged radially around the first annular wall 46 and the first annular wall 46 supports the second annular wall 48. The fourth annular wall 52 is spaced radially from and is arranged radially within the third annular wall 50 and the third annular wall 50 supports the fourth annular wall 52. The upstream end of the first annular wall 46 is secured to the upstream end wall structure 44 and the upstream end of the third annular wall 50 is secured to the upstream end wall structure 44. The upstream end wall structure 44 has a plurality of circumferentially spaced apertures 54 and each aperture 54 has a respective one of a plurality of fuel injectors 56 located therein. The fuel injectors 56 are arranged to supply fuel into the annular combustion chamber 15 during operation of the gas turbine engine 10.
The first annular wall 46 has a plurality of mounting apertures 58 extending there-though and the second annular wall 48 has a plurality of fasteners 60 extending radially there-from. Each fastener 60 on the second annular wall 48 extends radially through a corresponding mounting aperture 58 in the first annular wall 46. A cooperating fastener 62 locates on each of the fasteners 60 extending through the mounting apertures 58 in the first annular wall 46. A washer 64 is positioned between each fastener 60 on the second annular wall 48 and the cooperating fastener 62. Each washer 64 has a first surface 66 abutting an outer surface of the first annular wall 46 and a second surface 68 abutting a surface of the cooperating fastener 62. The second annular wall 48 comprises a plurality of segments, or tiles, 48A, 48B and 48C and the segments, or tiles, 48A, 48B and 48C are arranged circumferentially and axially around the first annular wall 46. The axially extending edges of adjacent segments, or tiles, 48A, 48B and/or 48C may abut each other or may overlap each other and the circumferentially extending ends of adjacent segments, or tiles, 48A, 48B and 48C are spaced from each other.
Similarly, the third annular wall 50 has a plurality of mounting apertures 70 extending there-though and the fourth annular wall 52 has a plurality of fasteners 72 extending radially there-from. Each fastener 72 on the fourth annular wall 52 extends radially through a corresponding mounting aperture 70 in the third annular wall 50. A cooperating fastener 74 locates on each of the fasteners 72 extending through the mounting apertures 70 in the third annular wall 50. A washer 76 is positioned between each fastener 72 on the fourth annular wall 52 and the cooperating fastener 74. Each washer 76 has a first surface 78 abutting an outer surface of the third annular wall 50 and a second surface 80 abutting a surface of the cooperating fastener 74. The fourth annular wall 52 comprises a plurality of segments, or tiles, 52A, 52B and 52C and the segments, or tiles, 52A, 52B and 52C are arranged circumferentially and axially adjacent to each other to define the fourth annular wall 52. The axially extending edges of adjacent segments, or tiles, 52A, 52B and/or 52C may abut each other or may overlap each other and the circumferentially extending ends of adjacent segments, or tiles, 52A, 52B and 52C are spaced from each other.
The fasteners 60 and 72 on the second and fourth annular walls 48 and 52 are threaded studs which are cast integrally with the segments, or tiles, 48A, 48B, 48C, 52A 52B and 52C or may be secured to the segments, or tiles, 48A, 48B, 48C, 52A, 52B and 52C by welding, brazing etc. Alternatively, the fasteners, e.g. threaded studs are formed by additive layer manufacturing integrally with the segments, or tiles 48A, 48B, 48C, 52A 52B and 52C. The cooperating fasteners 62 and 74 are nuts.
The first and third annular walls 46 and 50 form outer walls of the annular combustion chamber 15 and the second and fourth annular walls 48 and 52 form inner walls of the annular combustion chamber 15. The second annular wall 48 comprises at least one row of circumferentially arranged tiles and in this example there are three rows 48A, 48B and 48C of circumferentially arranged tiles and the tiles 48A form an axially upstream row of circumferentially arranged tiles, the tiles 48B form an axially intermediate row of circumferentially arranged tiles and the tiles 48C form an axially downstream row of circumferentially arranged tiles. Similarly, the fourth annular wall 52 comprises at least one row of circumferentially arranged tiles and in this example there are three rows 52A, 52B and 52C of circumferentially arranged tiles and the tiles 52A form an axially upstream row of circumferentially arranged tiles, the tiles 52B form an axially intermediate row of circumferentially arranged tiles and the tiles 52C form an axially downstream row of circumferentially arranged tiles. The tiles 52A are an upstream row of tiles with respect to the tiles 52B and similarly the tiles 52B are a downstream row of tiles with respect to the tiles 52A. The tiles 52B are an upstream row of tiles with respect to the tiles 52C and similarly the tiles 52C are a downstream row of tiles with respect to the tiles 52B. The second annular wall 48 and/or the fourth annular wall 52 may comprise any suitable number of rows of tiles.
The combustion chamber in this arrangement also comprises a plurality of dilution ports 71 in the radially inner annular wall structure 40 and a plurality of dilution ports 73 in the radially outer annular wall structure 42. The dilution ports 73 in the radially outer annular wall structure 42 comprise a plurality of aligned apertures 79 and 81 in the annular outer wall 50 and the tiles 52B of the annular inner wall 52. The dilution ports 71 in the radially inner annular wall structure 40 comprise a plurality of aligned apertures 75 and 77 in the annular outer wall 46 and the tiles 48B of the annular inner wall 48. The dilution ports 71 and 73 supply dilution air H into the combustion chamber to control emissions.
The annular outer wall 50 has a plurality of impingement cooling apertures 67 extending there-through to direct coolant onto the outer surface of the tiles 52A, 52B and 52C and the tiles 52A, 52B and 52C have effusion cooling apertures 69 extending there-through to provide a film of coolant onto the inner surfaces of the tiles 52A, 52B and 52C respectively. The impingement cooling apertures 67 are generally arranged perpendicularly to the surfaces of the annular outer wall 50 and the outer surfaces of the tiles 52A, 52B and 52C respectively. However, the impingement cooling apertures 67 may be arranged at other suitable angles to the surfaces of the annular outer wall 50 and the outer surfaces of the tiles 52A, 52B and 52C respectively. The effusion cooling apertures 69 are generally arranged at an angle, for example 30°, to the inner surfaces of the tiles 52A, 52B and 52C but other suitable angles may be used. Some effusion cooling apertures 69 may be arranged perpendicularly to the inner surfaces of the tiles 52A, 52B and 52C and some of the effusion cooling apertures 69 may be arranged at an angle, for example 30°, to the inner surfaces of the tiles 52A, 52B and 52C.
The downstream end of each tile 52A in the upstream row of tiles 52A has a rail 53 which extends from the outer surface of the tile 52A at the downstream end of the tile 52A towards and seals with an inner surface of the annular outer wall 50 and a lip 63 extends in a downstream direction towards but is spaced from the upstream ends of the tiles 52B in the downstream row of tiles 52B. The lip 63 extends from the junction between the rail 53 at the downstream end of the tile 52A and the main body of the tile 52A. The inner surface of the lip 63 forms a continuation of the inner surface of the main body of the tile 52A. The annular outer wall 50 has at least one row of apertures 57 to direct coolant F onto the outer surfaces of the lips 63 at the downstream ends of the tiles 52A in the upstream row of tiles 52A. The at least one row of apertures 57 is arranged to supply the coolant F to a chamber, e.g. an annular chamber, 65 defined between the inner surface of the annular outer wall 50, the rails 53 at the downstream ends of the tiles 52A and the lips 63 at the downstream ends of the tiles 52A in the upstream row of tiles 52A. The upstream end of each tile 52A in the upstream row of tiles 52A has a rail 51 which extends from the upstream end of the tile 52A towards and seals with the inner surface of the annular outer wall 50.
Each tile 52A in the upstream row of tiles 52A also has two rails 55, each rail 55 extends axially along a respective one of the circumferentially spaced edges and each rail 55 also extend towards and seal against the inner surface of the annular outer wall 50. Thus, each tile 52A has rails 51, 53 and 55 which extend around the periphery of the tile 52A to form a closed chamber between each tile 52A and the annular outer wall 50.
The downstream end of each tile 52B in the intermediate row of tiles 52B has a rail 53 which extends from the outer surface of the tile 52B at the downstream end of the tile 52B towards and seals with the inner surface of the annular outer wall 50 and a lip 63 extends in a downstream direction towards but is spaced from the upstream ends of the tiles 52C in the downstream row of tiles 52C. The lip 63 extends from the junction between the rail 53 at the downstream end of the tile 52B and the main body of the tile 52B. The inner surface of the lip 63 forms a continuation of the inner surface of the main body of the tile 52B. The annular outer wall 50 has at least one row of apertures 57 to direct coolant onto the outer surfaces of the lips 63 at the downstream ends of the tiles 52B in the intermediate row of tiles 52B. The at least one row of apertures 57 is arranged to supply the coolant to a chamber, e.g. an annular chamber, 65 defined between the inner surface of the annular outer wall 50, the rails 53 at the downstream ends of the tiles 52B and the lips 63 at the downstream ends of the tiles 52B in the intermediate row of tiles 52B. The upstream end of each tile 52B in the intermediate row of tiles 52B has a rail 51 which extends from the upstream end of the tile 52B towards and seals with the inner surface of the annular outer wall 50. The rail 51 at the upstream end of each tile 52B in the intermediate row of tiles 52B in this particular example also extends in an upstream direction. Each tile 52B in the intermediate row of tiles 52B also has two rails 55, each rail 55 extends axially along a respective one of the circumferentially spaced edges and each rail 55 also extend towards and seal against the inner surface of the annular outer wall 50. Thus, each tile 52B has rails 51, 53 and 55 which extend around the periphery of the tile 52B to form a closed chamber between each tile 52B and the annular outer wall 50.
The downstream end of each tile 52C in the downstream row of tiles 52C has a rail (not shown) which extends from the outer surface of the tile 52C at the downstream end of the tile 52C towards and seals with the inner surface of the annular outer wall 50. The upstream end of each tile 52C in the downstream row of tiles 52C has a rail 51 which extends from the upstream end of the tile 52C towards and seals with the inner surface of the annular outer wall 50. The rail 51 at the upstream end of each tile 52C in the downstream row of tiles 52C in this particular example also extends in an upstream direction. Each tile 52C in the downstream row of tiles 52C also has two rails 55, each rail 55 extends axially along a respective one of the circumferentially spaced edges and each rail 55 also extend towards and seal against the inner surface of the annular outer wall 50. Thus, each tile 52C has rails 51, 53 and 55 which extend around the periphery of the tile 52C to form a closed chamber between each tile 52C and the annular outer wall 50. The tiles 52C in the downstream row of tiles 52C may have dilution apertures or may not have dilution apertures. Similarly, the tiles 52A in the upstream row of tiles 52A may have dilution apertures or may not have dilution apertures. Additionally, the tiles 52B in the intermediate row of tiles 52B may not have dilution apertures.
It is to be noted that the annular outer wall 50 has a bend 82 and the rail 53 at the downstream end of each tile 52A is upstream of the bend 82 in the annular outer wall 50 and the rail 51 at the upstream end of each tile 52B is downstream of the bend 82 in the annular outer wall 50. It is also to be noted that the apertures 57 in the outer annular wall 50, which are arranged to direct coolant onto the lip 63 at the downstream end of each tile 52A, are positioned upstream of the bend 82 in the annular outer wall 50 and downstream of the rail 53 at the downstream end of each tile 52A. Likewise, the annular outer wall 46 may have a bend and the rail at the downstream end of each tile 48A is upstream of the bend in the annular outer wall 46 and the rail at the upstream end of each tile 48B is downstream of the bend in the annular outer wall 46. It is also to be noted that the apertures in the outer annular wall 46, which are arranged to direct coolant onto the lip at the downstream end of each tile 48A, are positioned upstream of the bend in the annular outer wall 46 and downstream of the rail at the downstream end of each tile 48A. However, it may be equally possible to provide the apertures 57 in the outer annular wall 50, which are arranged to direct coolant onto the lip 63 at the downstream end of each tile 52A, downstream of the bend 82 in the annular outer wall 50 and downstream of the rail 53 at the downstream end of each tile 52A. Similarly, it may be equally possible to provide the apertures in the outer annular wall 46, which are arranged to direct coolant onto the lip at the downstream end of each tile 48A, downstream of the bend in the annular outer wall 46 and downstream of the rail at the downstream end of each tile 48A. The apertures in the row of apertures 57 in the outer annular wall 50 may be arranged perpendicularly to the outer surfaces of the lips 63 of the tiles 52A or may be arranged at other suitable angles. The apertures in the row of apertures 57 in the outer annular wall 46 may be arranged perpendicularly to the outer surfaces of the lips of the tiles 48A or may be arranged at other suitable angles.
The fasteners 60 are generally provided at the corners of the tiles 48A, 48B, 48C and the fasteners 72 are generally provided at the corners of the tiles 52A, 52B and 52C. The row, or rows, of apertures 57 in the annular outer wall 50 which direct coolant onto the lips 63 of the tiles 52A reduce the strength of the annular outer wall 50. The rails 53 at the downstream ends of the tiles 52A are positioned close to the row, or rows, of apertures 57 in the annular outer wall 50. The points where the fasteners 72 used to secure the tiles 52A to the annular outer wall 50 are close to the rails 53 at the downstream ends of the tiles 52A. The bend 82 in the annular outer wall 50 is positioned close to the row or rows of apertures 57 in the annular outer wall 50.
The rail 53 at the downstream end of each tile 52A is provided with at least one groove 86 at its end remote from the tile 52A and the at least one groove 86 defines at least one slot with the inner surface of the annular outer wall 50. The at least one groove 86 and hence the at least one slot is arranged in a region 84 downstream of a fastener 72 at the downstream end of the tile 52A. In this arrangement the rail 53 at the downstream end of each tile 52A is provided with a plurality of grooves 86 at its end remote from the tile 52A and each groove 86 defines a slot with the inner surface of the annular outer wall 50. Each tile 52A has a plurality of grooves 86, and hence a plurality of slots, are arranged in the region 84 downstream of the fastener 72. As mentioned above each tile 52A has a plurality of fasteners 72 positioned upstream of the rail 53 and the rail 53 of each tile 53A has a plurality of grooves 86 which define a plurality of slots with the inner surface of the annular outer wall 50. At least one groove 86, and hence at least one slot, of each tile 52A is arranged in a region 84 downstream of each fastener 72. In this arrangement the rail 53 at the downstream end of each tile 52A is provided with a plurality of grooves 86 at its end remote from the tile 52A and each groove 86 defines a slot with the inner surface of the annular outer wall 50 and a plurality of grooves 86, and hence a plurality of slots, of each tile 52A are arranged in a region 84 downstream of each fastener 72. There may for example be five grooves 86 in each region 84 and each region 84 may have a circumferential dimension of up to four times the diameter of a fastener 72. There may be one groove 84 and hence one slot, or a plurality of grooves 84 and hence a plurality of slots, arranged in each region 84 and each region 84 downstream of a corresponding fastener 72 may have a circumferential dimension of up to four times the diameter of the corresponding fastener 72. The grooves 86 in this arrangement are arranged perpendicularly to the surfaces of the rail 53, but the grooves 86 may be arranged at any suitable angle to the surfaces of the rail 53. The number of grooves 86, the depth of the grooves 86, the pitch of the grooves 86, and the orientation, e.g. angle, of the grooves 86 may be optimised for a particular geometry. The pitch of the apertures in the row of apertures 57 may be optimised for a particular geometry.
The rails 55 along the axially extending edges of the tiles 52A may be provided with at least one groove 88 at its end remote from the tile 52A and the at least one groove 88 defines at least one slot with the inner surface of the annular outer wall 50. There may be a plurality of grooves 88 in each of the rails of each tile 52A. The grooves 88 may be arranged perpendicular to the surfaces of the rails 55 or at any other suitable angle to the surfaces of the rails 55.
None of the apertures 57 in the at least one row of apertures in the annular outer wall 50 are arranged in a region 90 downstream of the at least one fastener 72 of the at least one tile 52A and in particular none of the apertures 57 in the at least one row of apertures in the annular outer wall 50 are arranged in a region 90 downstream of each fastener 72 of the at least one tile 52A. Each region 90 may have a circumferential dimension of up to four times the diameter of a fastener 72, but in this example each region 90 has a circumferential dimension less than the circumferential dimension of the corresponding region 84. Each region 90 may have a circumferential dimension of up to twice the diameter of the fastener 72. Thus, in the, or each, region 90 downstream of a fastener 72 the annular outer wall 50 is imperforate. The region 90 may have the same circumferential dimension as the corresponding region 84.
However, in some circumstances the region 84 may have a circumferential dimension greater than four times the diameter of a fastener 72 and/or the region 90 may have a circumferential dimension greater than twice the diameter of the fastener 72 to suit the need of a particular design.
The inner surface of the tiles 48A, 48B, 48C, 52A, 52B and 52C are provided with a thermal barrier coating 92 to further protect the tiles from the heat in the combustion chamber 15.
In operation the coolant F is directed with high velocity from the apertures 57 in the annular outer wall 50 to impinge upon the lips 63 at the downstream ends of the tiles 52A. The coolant flows from the lips 63 of the tiles 52A such that the coolant G flows predominantly axially over and across the rails 51 at the upstream ends of the tiles 52B and across and over the upstream ends of the tiles 52B. This axial flow of coolant G reduces, or prevents, the ingress of hot gases into the chamber 65 defined between the rails 53 and lips 63 of the tiles 52A and the annular outer wall 50. The axial flow of coolant G also enables an effective film of coolant to be formed, or re-formed, on the inner surfaces of the tiles 52B in the regions of the tiles 52B immediately upstream of the dilution apertures 81 of the tiles 52B. This reduces the temperature of the upstream ends of the tiles 52B and the downstream ends of the tiles 52A and the temperature of the annular outer wall 50 between the rails 53 of the tiles 52A and the rails 51 of the tiles 52B.
As mentioned previously, coolant is directed to flow through the impingement cooling apertures 67 onto the outer surface of the tiles 52A, 52B and 52C and coolant is directed through the effusion cooling apertures 69 to provide a film of coolant on the inner surfaces of the tiles 52A, 52B and 52C respectively. Some of the coolant supplied by the impingement cooling apertures 67 flows around the fasteners 72 at the downstream ends of the tiles 52A, through the grooves 86 into the chamber 65 to mix with and join the flow of coolant F from the apertures 57.
The grooves 86 in the rail 53 in the region 84 downstream of each fastener 72 reduce the conduction of heat from the tile 52A into the annular outer wall 50 by reducing the area of contact between the rail 53 and the annular outer wall 50 in the region 84 downstream of the fastener 72. The grooves 86 allow a flow of coolant I over the inner surface of the annular wall 50 in the region 84 downstream of each fastener 72. The grooves 86 also enhance the flow of coolant around the fasteners 72 to cool the fasteners 72 and hence reduce the temperature of the tiles 52A in the region of the fasteners 72 and in particular the base of the fasteners 72. This reduces the potential for cracks to initiate and propagate in the annular outer wall 50 by reducing the temperature of the annular outer wall 50 and removing the stress concentration features. The cooling of the fasteners 72 reduces creep of the fasteners 72 and maintains the clamping load of the fastener 72 and tile 52A onto the annular outer wall 50.
The at least one row of apertures 57 in the annular outer wall 50 is arranged such that there are no apertures in each region 90 downstream of a fastener 72 of each tile 52A, each region 90 downstream of a fastener 72 of the annular outer wall 50 is imperforate. These regions 90 are arranged to arrest crack propagation should any crack be initiated and propagated in the annular outer wall 50.
The provision of the grooves 86 in the regions 84 of the rails 53 provides a flow of coolant over the inner surface of the annular outer wall 50 and the outer surfaces of the lips 63 of the tiles 52A which compensates for the regions 90 of the annular wall 50 where there are no apertures 57 to direct coolant through the annular outer wall 50 and onto the outer surfaces of the lips 63 of the tiles 52A.
The tiles 52B and 52C of the radially outer annular wall structure 42 may be arranged in a similar manner to the tiles 52A. Thus, the rails at the downstream ends of the tiles 52B may be provided with grooves 86 downstream of at least one fastener 72 and the row of apertures 57 arranged to direct coolant onto the lips 63 may be provided with a region without apertures and/or the rails at the downstream ends of the tiles 52C may be provided with grooves 86 downstream of at least one fastener 72 and the row of apertures 57 arranged to direct coolant onto the lips 63 may be provided with a region without apertures.
The tiles 48A, 48B and 48C of the radially inner annular wall structure 40 may be arranged in a similar manner to the tiles 52A. Thus, the rails at the downstream ends of the tiles 48A may be provided with grooves downstream of at least one fastener 60 and the row of apertures arranged to direct coolant onto the lips may be provided with a region without apertures and/or the rails at the downstream ends of the tiles 48B may be provided with grooves downstream of at least one fastener 60 and the row of apertures arranged to direct coolant onto the lips may be provided with a region without apertures and/or the rails at the downstream ends of the tiles 48C may be provided with grooves downstream of at least one fastener 60 and the row of apertures arranged to direct coolant onto the lips may be provided with a region without apertures.
Each of the tiles 48A, 48B and 48C and each of the tiles 52A, 52B and 52C is parallelogram in shape in a plan view and in particular each of the tiles 48A, 48B and 48C and each of the tiles 52A, 52B and 52C is rectangular in a plan view. Each of the tiles 48A, 48B and 48C and each of the tiles 52A, 52B and 52C has longitudinally, axially, spaced ends and laterally, circumferentially, spaced edges. Each of the tiles 48A, 48B and 48C and each of the tiles 52A, 52B and 52C is arcuate and in particular is curved between its laterally spaced edges. Each of the tiles 48A, 48B and 48C has a rail extending around the periphery of a first surface, a radially inner surface, and the first surface is concave between its laterally spaced edges. Each of the tiles 52A, 52B and 52C has a rail extending around the periphery of a first surface, a radially outer surface, and the first surface is convex between its laterally spaced edges.
An advantage of the present disclosure is that the row or rows of apertures in the annular outer wall which direct coolant onto the lips of the tiles are provided with circumferential regions where there are no apertures to increase the strength of the annular outer wall and to arrest the propagation of any cracks circumferentially around the annular outer wall. The rails at the downstream ends of the tiles which are positioned close to the row of rows of apertures in the annular outer wall are provided with grooves at their ends remote from the tiles to reduce the conduction of heat from the tiles to the annular outer wall and hence reduce the stress in the annular outer wall adjacent the row or rows of apertures in the annular outer wall which direct coolant onto the lips of the tiles. The mechanical integrity of the annular outer wall and the fasteners of the tiles are improved by reducing the possibility of crack initiation and increasing the possibility of preventing the propagation of cracks around the annular outer wall whilst preserving cooling effectiveness. The arrangement reduces the loss of clamping load of the tiles.
Although the present disclosure has referred to the use of studs and nuts to secure the tiles to the particular supporting annular wall it may be possible to use bolts which are inserted through apertures in the tiles and respective apertures in the supporting annular wall and threaded into associated nuts or it may be possible to use threaded bosses on the tiles and bolts which are inserted through apertures in the supporting annular wall and into threaded into the respective bosses.
The combustion chamber may be an annular combustion chamber and the annular inner wall is spaced radially inwardly from the annular outer wall.
The combustion chamber may be an annular combustion chamber and the annular inner wall is spaced radially outwardly from the annular outer wall.
Although the present disclosure has referred to an annular combustion chamber is equally applicable to a tubular combustion chamber in which the annular inner wall is spaced radially inwardly from the annular outer wall.
The combustion chamber is a gas turbine engine combustion chamber.
Although the present disclosure has been described with reference to a turbofan gas turbine engine it is equally applicable to a turbojet gas turbine engine, a turbo-shaft gas turbine engine and a turbo-propeller gas turbine engine.
Although the present disclosure has been described with reference to an aero gas turbine engine it is equally applicable to a marine gas turbine engine, an automotive gas turbine engine and an industrial gas turbine engine.
The tiles may be made by casting or by additive layer manufacturing, e.g. direct laser deposition (DLD) or powder bed laser deposition. The tiles may comprise a nickel based superalloy, a cobalt based superalloy or an iron based superalloy.
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 subcombinations of one or more features described herein.

Claims

A combustion chamber arrangement (15) comprising an annular outer wall (50) and an annular inner wall (50) spaced from the annular outer wall (50), the annular inner wall (52) comprising at least one row of tiles (52A, each row of tiles (52A) comprising a plurality of circumferentially arranged tiles (52A), the downstream end of each tile (52A) in the at least one row of tiles (52A) having a rail (53) extending from the downstream end of the tile (52A) towards and sealing with an inner surface of the annular outer wall (50) and a lip (63) extending in a downstream direction from the downstream end of the tile (52A), the annular outer wall (50) having at least one row of apertures (57) to direct coolant onto the outer surfaces of the lips (63) at the downstream ends of the tiles (52A) in the at least one row of tiles (52A), each tile (52A) in the at least one row of tiles (52A) having at least one fastener (72) positioned upstream of the rail (53), the at least one fastener (72) of each tile (52A) in the at least one row of tiles (52A) extending from the tile (52A) and through a corresponding mounting aperture (70) in the annular outer wall (50) to secure the tile (52A) to the annular outer wall (50), the rail (53) of at least one tile (52A) defining at least one slot (86) with the inner surface of the annular outer wall (50), the at least one slot (86) of the at least one tile (52A) being arranged in a region (84) downstream of the at least one fastener (72) and none of the apertures (57) in the at least one row of apertures (57) in the annular outer wall (50) being arranged in a region (90) downstream of the at least one fastener (72) of the at least one tile (52A).
A combustion chamber arrangement as claimed in claim 1 wherein the rail (53) of each tile (52A) defining at least one slot (86) with the inner surface of the annular outer wall (50), the at least one slot (86) of each tile (52A) being arranged in a region (84) downstream of the at least one fastener (72) and none of the apertures (57) in the at least one row of apertures (57) being arranged in the region (84) downstream of the at least one fastener (72) of each tile (52A).
A combustion chamber arrangement as claimed in claim 2 wherein the rail (53) of each tile (52A) defining a plurality of slots (86) with the inner surface of the annular outer wall (50) and the plurality of slots (86) of each tile (52A) being arranged in the region (84) downstream of the at least one fastener (72).
A combustion chamber arrangement as claimed in any of claims 1 to 3 wherein each tile (52A) in the at least one row of tiles (52A) having a plurality of fasteners (72) positioned upstream of the rail (53), each fastener (72) extending from the tile (52A) and through a corresponding mounting aperture (70) in the annular outer wall (50) to secure the tile (52A) to the annular outer wall (50).
A combustion chamber arrangement as claimed in any of claims 1 to 4 wherein the rail (53) of each tile (52A) in the at least one row of tiles (52A) defining a plurality of slots (86) with the inner surface of the annular outer wall (50), at least one slot (86) of each tile (52A) being arranged in a region (84) downstream of each fastener (72) and none of the apertures (57) in the at least one row of apertures (57) in the annular outer wall (50) being arranged in the region (90) downstream of each fastener (72) of each tile (52A).
A combustion chamber arrangement as claimed in claim 5 wherein a plurality of slots (86) of each tile (52A) being arranged in a region (84) downstream of each fastener (72).
A combustion chamber arrangement as claimed in any of claims 1 to 6 wherein the annular inner wall (52) comprising an upstream row of tiles (52A) and a downstream row of tiles (52B), the downstream end of each tile (52A) in the upstream row of tiles (52A) having a lip (63) extending in a downstream direction towards but spaced from the upstream ends of the tiles (52B) in the downstream row of tiles (52B), the annular outer wall (50) having at least one row of apertures (57) to direct coolant onto the outer surfaces of the lips (63) at the downstream ends of the tiles (52A) in the upstream row of tiles (52A), each tile (52A) in the upstream row of tiles (52A) having at least one fastener (72) positioned upstream of the rail (53), the at least one fastener (72) of each tile (52A) in the upstream row of tiles (52A) extending from the tile (52A) and through a corresponding mounting aperture (70) in the annular outer wall (50) to secure the tile (52A) to the annular outer wall (50), the rail (52A) of at least one tile (52A) defining at least one slot (86) with the inner surface of the annular outer wall (50), the at least one slot (86) of the at least one tile (52A) being arranged in a region (84) downstream of the at least one fastener (72) and none of the apertures (57) in the at least one row of apertures (57) in the annular outer wall (50) being arranged in the region (90) downstream of the at least one fastener (72) of the at least one tile (52A).
A combustion chamber arrangement as claimed in claim 7 wherein each tile (52A) in the upstream row of tiles (52A) having a plurality of fasteners (72) positioned upstream of the rail (53), each fastener (72) extending from the tile (52A) and through a corresponding mounting aperture (70) in the annular outer wall (50) to secure the tile(52A) to the annular outer wall (50).
A combustion chamber arrangement as claimed in claim 7 or claim 8 wherein the annular outer wall (50) having a bend (82), the rail (53) at the downstream end of each tile (52A) in the upstream row of tiles (52A) being arranged upstream of the bend (82) in the annular outer wall (50).
A combustion chamber arrangement as claimed in claim 9 wherein the at least one row of apertures (57) in the annular outer wall (50) being arranged upstream of the bend (82) in the annular outer wall (50) and downstream of the rail (53) at the downstream end of each tile (52A) in the upstream row of tiles (52A).
A combustion chamber arrangement as claimed in claim 7, claim 8, claim 9 or claim 10 wherein the upstream end of each tile (52B) in the downstream row of tiles (52B) having a rail (51) extending from the upstream end of the tile (52B) towards and sealing with an inner surface of the annular outer wall (50).
A combustion chamber arrangement as claimed in any of claims 1 to 6 wherein the annular outer wall (50) having a bend (82), the rail (53) at the downstream end of each tile (52A) in the at least one row of tiles (52A) being arranged upstream of the bend (82) in the annular outer wall (50).
A combustion chamber arrangement as claimed in claim 12 wherein the at least one row of apertures (57) in the annular outer wall (50) being arranged upstream of the bend (82) in the annular outer wall (50) and downstream of the rail (53) at the downstream end of each tile (52A) in the at least one row of tiles (52A).
A combustion chamber arrangement as claimed in any of claims 1 to 13 wherein a plurality of slots (86) being arranged in a region (84) downstream of the at least one fastener (72), the region (84) downstream of the at least one fastener (72) having a circumferential dimension of up to four times the diameter of the at least one fastener (72).
A combustion chamber arrangement as claimed in any of claims 1 to 14 wherein the annular outer wall (50) not having any apertures (57) arranged in a region (90) downstream of the at least one fastener (72), the region (90) downstream of the at least one fastener (72) having a circumferential dimension of up to four times the diameter of the at least one fastener (72).
A combustion chamber arrangement as claimed in claim 15 wherein the annular outer wall (50) not having any apertures (57) arranged in a region (90) downstream of the at least one fastener (72), the region (90) downstream of the at least one fastener (72) having a circumferential dimension of up to twice the diameter of the at least one fastener (72).