GB2564913A

GB2564913A - A combustion chamber and a combustion chamber fuel injector seal

Info

Publication number: GB2564913A
Application number: GB1713434.7A
Authority: GB
Inventors: Aurifielle Emmanuel; Resvanis Kyriakoulis
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2017-07-21
Filing date: 2017-08-22
Publication date: 2019-01-30
Also published as: GB201713434D0

Abstract

A combustion chamber (15 fig.1) includes an upstream end wall (44 fig.1), a fuel injector (56 fig.1) and a seal (58 fig.1). Each injector is arranged in a corresponding aperture (54 fig.1) in the wall around one of the injectors. Each seal has a first portion (60 fig.3), a second portion (62 fig.3) and a third portion (64 fig.3) with the second portion abutting the injector. The third portion is arranged at an angle between 0° and 50° to the axis of the seal and has circumferentially spaced radially and axially extending teeth (72). The seal may also include cooling apertures 68. The seals produce better mixing of the fuel and air mixture from the fuel injectors to reduce emissions produced in the combustion chamber.

Description

The present disclosure relates to a combustion chamber and in particular to a gas turbine engine combustion chamber and also relates to a combustion chamber fuel injector seal and in particular to a gas turbine engine combustion chamber fuel injector seal.

A combustion chamber comprises an upstream end wall, at least one annular wall, at least one fuel injector and at least one seal. The annular wall is secured to the upstream end wall and the upstream end wall has at least one aperture. Each fuel injector is arranged in a corresponding one of the apertures in the upstream end wall. Each seal is arranged in a corresponding one of the apertures in the upstream end wall and around the corresponding one of the fuel injectors. Each seal has a first portion, a second portion and a third portion. The second portion of each seal abuts the corresponding one of the fuel injectors. The third portion of each seal is arranged at the downstream end of the seal and the third portion increases in diameter in a downstream direction. The first portion of each seal is arranged upstream of the second portion and the first portion has a plurality of coolant apertures extending there-through.

The coolant apertures in the first portion of each seal direct the coolant therethrough with axial and radial velocity components towards the third portion of the seal. The coolant is turned by the third portion of each seal such that it flows radially outwardly. The coolant directed radially outwardly by the third portion of each seal mixes with a fuel and air mixture supplied into the combustion chamber by the corresponding one of the fuel injectors.

However, it is believed that mixing of fuel and air in the combustion chamber is a result of the aerodynamics and hydrodynamics produced by the fuel injector, or fuel injectors, and the expansion ratio determined by the diameter of the fuel injector, or fuel injectors, and the dimensions or cross-sectional area, of the combustion chamber, e.g. the diameter for a tubular combustion chamber or the difference in diameters for an annular combustion chamber. In particular, it is believed that the seal does not contribute to the process of mixing of the fuel and air. It has been found, in some but not all combustion tests, that if the amount of coolant supplied by the coolant apertures is increased that there is an increased amount of smoke produced by the combustion chamber.

The present disclosure seeks to produce a combustion chamber and a combustion chamber fuel injector seal which reduces or overcomes the above mentioned problem, e.g. contributes to the mixing process of the fuel and air in the combustion chamber.

According to a first aspect of the present disclosure there is provided a combustion chamber comprising an upstream end wall, at least one annular wall, at least one fuel injector and at least one seal, the at least one annular wall being secured to the upstream end wall, the upstream end wall having at least one aperture, each fuel injector being arranged in a corresponding one of the apertures in the upstream end wall, each seal being arranged in a corresponding one of the apertures in the upstream end wall and around the corresponding one of the fuel injectors, each seal having an upstream end, a downstream end, an inner surface facing the corresponding one of the fuel injectors and an outer surface facing away from the corresponding one of the fuel injectors, each seal abutting the corresponding one of the fuel injectors, the downstream end of each seal increasing in diameter in a downstream direction, the downstream end of each seal being arranged at an angle greater than 0° and less than 50° to the axis of the seal, the downstream end of each seal having a plurality of circumferentially spaced teeth, the teeth at the downstream end of each seal extending radially outwardly and axially away from the upstream end of the seal.

The downstream end of each seal may be arranged at an angle less than 45° to the axis of the seal. The downstream end of each seal may be arranged at an angle less than 40° to the axis of the seal. The downstream end of each seal may be arranged at an angle less than 30° to the axis of the seal. The downstream end of each seal may be arranged at an angle less than 20° to the axis of the seal. The downstream end of each seal may be arranged at an angle less than 10° to the axis of the seal.

The teeth may not be angled.

The teeth may be angled with a tangential, or circumferential, component. The teeth may be angled with a tangential, or circumferential, component between and including 20° and 60°.

The downstream end of each seal may be arcuate.

Each seal may have a plurality of coolant apertures extending there-through, each coolant aperture having an inlet in the inner surface and an outlet in the outer surface of the seal, the coolant apertures being arranged upstream of the downstream end of the seal, the outlet of each coolant aperture being axially spaced in a downstream direction from its inlet, the outlet of each coolant aperture being radially spaced from its inlet.

Each seal may have a first portion, a second portion and a third portion, the second portion abutting the corresponding one of the fuel injectors, the third portion being arranged at the downstream end of the seal, the third portion increasing in diameter in a downstream direction, the first portion being arranged upstream of the second portion, the first portion having a plurality of coolant apertures extending there-through, the coolant apertures extending through the first portion with axial and radial components.

Each seal may be circular in cross-section. Alternatively, each seal may be elliptical in cross-section.

Each seal may comprise a substantially cylindrical first portion, a substantially cylindrical second portion and a frustoconical third portion or a bell mouth third portion.

The first portion of each seal may have an inner diameter greater than the inner diameter of the second portion of that seal.

The axes of the coolant apertures in first portion of each seal may be arranged to intersect the third portion of the seal to direct coolant onto the third portion of the seal.

The third portion of each seal may have a plurality of circumferentially spaced radially and axially extending teeth at its downstream end at the maximum diameter of the third portion.

Each seal may comprise a fourth portion, the fourth portion of each seal being secured to the upstream end wall such that the seal may move radially with respect to the axis of the corresponding aperture in the upstream end wall.

The combustion chamber may be an annular combustion chamber comprising an annular upstream end wall, a radially inner annular wall, a radially outer annular wall, a plurality of fuel injectors and a plurality of seals and the annular upstream end wall having a plurality of apertures.

The fuel injector may be a rich bum fuel injector or a lean burn fuel injector.

The combustion chamber may be a gas turbine engine combustion chamber.

The gas turbine engine may be an industrial gas turbine engine, an automotive gas turbine engine, a marine gas turbine engine or an aero gas turbine engine.

The aero gas turbine engine may be a turbofan gas turbine engine, a turbojet gas turbine engine, a turbo-propeller gas turbine engine or a turbo-shaft gas turbine engine.

According to a second aspect of the present disclosure there is provided a combustion chamber fuel injector seal having a downstream end, the downstream end of the seal increasing in diameter in a downstream direction, the seal having an upstream end, a downstream end, an inner surface facing the fuel injector and an outer surface facing away from the fuel injector, each seal being arranged to abut the fuel injector, the downstream end of the seal increasing in diameter in a downstream direction, the downstream end of the seal being arranged at an angle greater than 0° and less than 50° to the axis of the seal, the downstream end of the seal having a plurality of circumferentially spaced teeth, the teeth at the downstream end of the seal extending radially outwardly and axially away from the upstream end of the seal.

The downstream end of the seal may be arranged at an angle less than 45° to the axis of the seal. The downstream end of the seal may be arranged at an angle less than 40° to the axis of the seal. The downstream end of the seal may be arranged at an angle less than 30° to the axis of the seal. The downstream end of the seal may be arranged at an angle less than 20° to the axis of the seal. The downstream end of the seal may be arranged at an angle less than 10° to the axis of the seal.

The teeth may not be angled.

The downstream end of the seal may be arcuate.

The seal may have a plurality of coolant apertures extending there-through, each coolant aperture having an inlet in the inner surface and an outlet in the outer surface of the seal, the coolant apertures being arranged upstream of the downstream end of the seal, the outlet of each coolant aperture being axially spaced in a downstream direction from its inlet, the outlet of each coolant aperture being radially spaced from its inlet.

The seal may have a first portion, a second portion and a third portion, the second portion being arranged to abut the fuel injector, the third portion being arranged at the downstream end of the seal, the third portion increasing in diameter in a downstream direction, the first portion being arranged upstream of the second portion, the first portion having a plurality of coolant apertures extending there-through, the coolant apertures extending through the first portion with axial and radial components.

The seal may be circular in cross-section. Alternatively, each seal may be elliptical in cross-section.

The seal may comprise a substantially cylindrical first portion, a substantially cylindrical second portion and a frustoconical third portion or a bell mouth third portion.

The first portion of the seal may have an inner diameter greater than the inner diameter of the second portion of the seal.

The axes of the coolant apertures in first portion of the seal may be arranged to intersect the third portion of the seal to direct coolant onto the third portion of the seal.

The third portion of the seal may have a plurality of circumferentially spaced radially and axially extending teeth at its downstream end at the maximum diameter of the third portion.

The seal may comprise a fourth portion, the fourth portion of the seal being securable to an upstream end wall such that the seal may move radially and respect to the axis of an aperture in the upstream end wall.

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 gas turbine engine having a combustion chamber according to the present disclosure.

Figure 2 is an enlarged cross-sectional view through a combustion chamber according to the present disclosure.

Figure 3 is an enlarged cross-sectional view of a combustion chamber fuel injector seal according to the present disclosure.

Figure 4 is a view in the direction of Arrow A of the combustion chamber fuel injector seal shown in Figure 3.

Figure 5 is a side view of the combustion chamber fuel injector seal shown in Figure 4.

Figure 6 is a further enlarged view of a portion of the combustion chamber fuel injector seal shown in Figure 5 showing the teeth.

Figure 7 is a view in the direction of Arrow A of an alternative combustion chamber fuel injector seal shown in Figure 3.

Figure 8 is a side view of the combustion chamber fuel injector seal shown in Figure 7.

Figure 9 is a further enlarged view of a portion of the combustion chamber fuel injector seal shown in Figure 8 showing the teeth.

Figure 10 is a cross-sectional view through a fuel injector shown in Figure 2.

Figure 11 is a cross-sectional view through an alternative fuel injector shown in Figure 2.

With reference to figure 1, a gas turbine engine is generally indicated at 10, having a principal and rotational axis X-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 fan nacelle 24 generally surrounds the fan 12 and defines the intake 11 and a fan duct 23. The fan nacelle 24 is secured to the core engine by fan outlet guide vanes 25.

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 into the intermediate pressure compressor 13 and a second air flow which passes through the bypass duct 23 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, the intermediate pressure compressor 13 and the fan 12, each by suitable interconnecting shaft 20, 21 and 22 respectively.

The combustion chamber 15, as shown more clearly in figure 2, is an annular combustion chamber 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. The combustion chamber 15 also comprises a plurality of fuel injectors 56 and a plurality of seals 58. Each fuel injector 56 is arranged in a corresponding one of the apertures 54 in the upstream end wall structure 44 and each seal 58 is arranged in a corresponding one of the apertures 54 in the upstream end wall structure 44 and each seal 58 is arranged around, e.g. surrounds, the corresponding one of the fuel injectors 56. The fuel injectors 56 are arranged to supply fuel into the annular combustion chamber 15 during operation of the gas turbine engine 10.

The second annular wall 48 comprises a plurality of rows of combustion chamber tiles 48A and 48B and the fourth annular wall 52 comprises a plurality of rows of combustion chamber tiles 52A and 52B. The combustion chamber tiles 48A and 48B are secured onto the first annular wall 46 by threaded studs, washers and nuts and the combustion chamber tiles 52A and 52B are secured onto the third annular wall 50 by threaded studs, washers and nuts.

Figures 3 to 6 show one of the seals 58 in more detail. Each seal 58 has a first portion 60, a second portion 62, a third portion 64 and a fourth portion 66. Each seal 58 has an inner surface 58A facing the corresponding one of the fuel injectors 56 and an outer surface 58A facing away from the corresponding one of the fuel injectors 56. The third portion 64 of each seal 58 has an upstream surface 58C and a downstream surface 58D. The second portion 62 of each seal 58 abuts and seals against the corresponding one of the fuel injectors 56. The first portion 60 of each seal 58 is arranged upstream of the second portion 62 and the third portion 64 of the seal 58 and is arranged downstream of the second portion 62 at the downstream end of the seal 58. The third portion 64 of each seal 58 increases in diameter in a downstream direction from the second portion 62 to a maximum diameter at the downstream end of the seal 58. The first portion 60 of each seal 58 has a plurality of coolant apertures 68 extending there-through and the coolant apertures 68 extend through the first portion 60 with axial and radial components, e.g. each coolant aperture 68 extends axially and radially through the first portion 62 of each seal. Each coolant aperture 68 has an inlet in the inner surface 58A and an outlet in the outer surface 58B of the seal 58. The outlet of each coolant aperture 68 is arranged axially spaced in a downstream direction from its inlet and the outlet of each coolant aperture 68 is arranged radially spaced from its inlet.

Each seal 58 is circular in cross-section and has an axis 59 and comprises a substantially cylindrical first portion 60, a substantially cylindrical second portion 62 and a divergent, or flared, third portion 64. The third portion 64 may be frustoconical or may be a bell mouth. The first portion 60 of each seal 58 has an inner diameter greater than the inner diameter of the second portion 62 of that seal 58. The inner surface 58A is a radially inner surface and the outer surface 58B is a radially inner surface. The fourth portion 66 of each seal 58 comprises a flange which extends radially from the first portion 60 of the seal 58. The fourth portion 66 of each seal 58 is secured to the upstream end wall structure 44 such that the seal 58 may move radially and axially with respect to the axis of the corresponding aperture 54 in the upstream end wall structure 44. The fourth portion 66 of each seal 58 may for example be trapped between the upstream surface of the upstream end wall structure 44 and a ring which is removably secured to the upstream end wall structure 44, for example by nuts and bolts or nuts and studs.

The coolant from the coolant apertures 68 in this arrangement impinges on the upstream surface 58C of the third portion 64 of the seal 58 to provide impingement cooling of the third portion 64. The coolant apertures 68 typically have a diameter between and including 0.5mm and 4mm and the number of holes depends upon the diameter of the seal 58, but the circumferential spacing between cooling apertures 68 is not less than the diameter of the coolant apertures 68. The coolant apertures 68 are angled with a radial component between and including 10° and 70°.

The coolant apertures 68 may be angled with a tangential component so that the coolant from the coolant apertures 68 swirls in the same direction as the swirl of the swirling fuel and air mixture from the fuel injector 56. The coolant apertures 68 in the first portion 60 may be angled with a tangential component to introduce a tangential velocity component to the coolant flowing there-through so as to match, or closely match, the swirling fuel and air mixture from the associated fuel injector 56. The coolant flowing from the coolant apertures 68 may match the swirl or enhance the swirl of the fuel and air mixture from the fuel injector 56 to improve mixing. The coolant apertures 68 are angled with a tangential, or circumferential, component between and including 20° and 60°.

The downstream end of each seal 58 is arranged at an angle greater than 0° and less than 50° to the axis 59 of the seal 58. The downstream end of each seal 58 may be arranged at an angle less than 45° to the axis 59 of the seal 58. The downstream end of each seal 58 may be arranged at an angle less than 40° to the axis 59 of the seal 58. The downstream end of each seal 58 may be arranged at an angle less than 30° to the axis 59 of the seal 58. The downstream end of each seal 58 may be arranged at an angle less than 20° to the axis 59 of the seal 58. The downstream end of each seal may be arranged at an angle less than 10° to the axis 59 of the seal 58.

The third portion 64 of the seal 58 is serrated, e.g. has chevrons, at its downstream end at the maximum diameter of the third portion 64. The serrated downstream end comprises a plurality of circumferentially spaced teeth 72 which are separated by spaces, or slots, 73. The downstream end of the third portion 64 comprises a plurality of slots, 73 extending there-through and the slots 73 extend through the third portion 64 with an axial component. Each slot 73 has an inlet in an upstream surface 58C of the third portion 64 and an outlet in a downstream surface 58D of the third portion 64 of the seal 58. The outlet of each slot 73 is arranged axially spaced in a downstream direction from its inlet.

Each seal 58 has a concave surface defined by the outer surface 58B and the upstream surface 58C and a convex surface defined by the inner surface 58A and the downstream surface 58D. It is to be noted that the downstream end of each seal 58 is arranged at an angle greater than 0° and less than 50° to the axis 59 of the seal 58 and that the downstream end of each seal 58 has a plurality of circumferentially spaced teeth 72. However, the angle of the downstream end of each seal 58 is such that pressure difference between the concave surface and the convex surface is not too great. The fuel injector 56 associated with each seal 58 has one or more swirlers which produces an air flow which has a high velocity adjacent to the downstream surface 58D of the seal 58 whereas the air flow over the outer surface 58B and upstream surface 58C has a much lower velocity. Thus, it is believed that some air, or air and fuel, flows radially outwardly through the slots 73 between circumferentially adjacent pairs of teeth 72 of each seal 58 and some air flows axially and radially along the teeth 72 to the downstream ends, tips, of the teeth 72 of each seal 58. The air, or air and fuel, flowing radially outwardly through the slots 73 and the air flowing to the downstream ends, tips, of the teeth 72 of each seal 58 have different velocities and thus create a turbulent fluid flow, turbulent air flow or turbulent air and fuel flow. The turbulent flow takes the form of vortex tubes which produce mixing and increases the fuel to air mixture uniformity and decreases the smoke and soot emissions.

The teeth 72 and spaces, slots, 73 enhance the mixing between the coolant and the fuel and air mixture from the fuel injector 56. The teeth 72 and spaces, slots, 73 produce enhanced mixing of the coolant and the fuel and air mixture from the associated fuel injector 56 by introducing stream wise vorticity.

The teeth 72 and spaces, slots, 73 typically have a circumferential dimension between and including 0.5mm and 4mm and the teeth 72 have a radial dimension between and including 0.5mm and 4mm. Each of the teeth 72 has the same radial dimension, each of the teeth 72 has the same circumferential dimension and each of the slots 73 has the same circumferential dimension. Each pair of circumferentially adjacent teeth 72 and the associated slot 73 may define a part elliptical shape, e.g. a half elliptical shape. However, each pair of circumferentially adjacent teeth 72 and the associated slot may define other suitable shapes, the radially inner ends of the teeth 72 may be joined by a radius. The teeth 72 may have a radial dimension of 1 /20^th to 1/10^th of the inner diameter of the seal 58. The number of teeth 72 and slots 73 may be the same as the number of coolant apertures 68 or may be fewer than the number of coolant apertures 68 or greater than the number of coolant apertures 68, e.g. two teeth, or two slots, per coolant aperture 68.

The seals 58 may be manufactured for example by casting and then drilling, e.g. ECM, EDM or laser drilling, the coolant apertures 68. The seals 58 may be manufactured by casting using cores to define the coolant apertures 68 and then removing, e.g. dissolving, the cores. The two above methods may or may not involve machining to form the slots 73 and the teeth 72. Alternatively, the seals 58 may be manufactured by additive layer manufacturing, e.g. powder bed laser deposition.

Figures 7 to 9 show an alternative seal 158 in more detail. The seal 158 is substantially the same as the seal 58 in figures 5 to 6 and like parts are denoted by like numerals. The seal has teeth 158 and slots but differs in that the downstream end of each seal 158 has a first set of teeth 172A and a second set of teeth 172B. The teeth of the first set of teeth 172A and the teeth of the second set of teeth 172B are arranged circumferentially alternately around the downstream end of the seal 158. The teeth of the first set of teeth 172A are arranged at a smaller angle relative to the axis 59 of the seal 158 than the teeth of the second set of teeth 172B and the downstream ends of the teeth of the first set of teeth 172A are arranged at the same radius as the downstream ends of the teeth of the second set of teeth 172B and thus the teeth of the first set of teeth 172A have a greater length than the teeth of the second set of teeth 172B.

The seals 158 may be manufactured for example by casting and then drilling,

e.g. ECM, EDM or laser drilling, the coolant apertures 68. The seals 158 may be manufactured by casting using cores to define the coolant apertures 68 and then removing, e.g. dissolving, the cores. The two above methods may or may not involve machining to form the slots 73 and the teeth 72. Alternatively, the seals 158 may be manufactured by additive layer manufacturing, e.g. powder bed laser deposition.

In another alternative seal arrangement, not shown, the seal is substantially the same as the seal 58 in figures 5 to 6. The seal has teeth and slots but differs in that the downstream end of each seal has a first set of teeth and a second set of teeth. The teeth of the first set of teeth and the teeth of the second set of teeth are arranged circumferentially alternately around the downstream end of the seal. The teeth of the first set of teeth have a greater length than the teeth of the second set of teeth and thus the downstream ends of the teeth of the first set of teeth are arranged at a greater radius than the downstream ends of the teeth of the second set of teeth.

These seals may also be manufactured for example by casting and then drilling, e.g. ECM, EDM or laser drilling, the coolant apertures. These seals may be manufactured by casting using cores to define the coolant apertures and then removing, e.g. dissolving, the cores. The two above methods may or may not involve machining to form the slots and the teeth. Alternatively, these seals may be manufactured by additive layer manufacturing, e.g. powder bed laser deposition.

In another seal arrangement, the seal is substantially the same as that shown in figures 5 to 6 and has teeth and slots but differs in that the downstream end of the each seal has a first set of teeth, a second set of teeth and a third set of teeth. The teeth of the first set of teeth have a greater length than the teeth of the second set of teeth, the teeth of the second set of teeth have a greater length than the second set of teeth and thus the downstream ends of the teeth of the first set of teeth are arranged at a greater radius than the downstream ends of the teeth of the second set of teeth and the downstream ends of the second set of teeth are arranged at a greater radius than the third set of teeth. A tooth of the first set of teeth, a tooth of the second set of teeth and a tooth of the third set of teeth may be arranged sequentially circumferentially around the downstream end of the seal or each tooth of the second set of teeth may be arranged between a tooth of the first set of teeth and a tooth of the third set of teeth at the downstream end of the seal.

In another seal arrangement, the seal is substantially the same as that shown in figures 5 to 6 and has teeth and slots but differs in that the downstream end of the each seal has a first set of teeth, a second set of teeth and a third set of teeth. The teeth of the first set of teeth are arranged at a smaller angle relative to the axis of the seal than the teeth of the second set of teeth, the teeth of the second set of teeth are arranged at a smaller angle relative to the axis of the seal than the third set of teeth and the downstream ends of the teeth of the first set of teeth, the downstream ends of the second set of teeth and the downstream ends of the teeth of the third set of teeth are arranged at the same radius and thus the teeth of the first set of teeth have a greater length than the teeth of the second set of teeth and the second set of teeth have a greater length that the teeth of the third set of teeth. A tooth of the first set of teeth, a tooth of the second set of teeth and a tooth of the third set of teeth may be arranged sequentially circumferentially around the downstream end of the seal or each tooth of the second set of teeth may be arranged between a tooth of the first set of teeth and a tooth of the third set of teeth at the downstream end of the seal.

In any of the above described arrangements each pair of circumferentially adjacent teeth and the associated slot may define a part elliptical shape or a half elliptical shape. In any of the above described arrangements each pair of circumferentially adjacent teeth and the associated slot may define other suitable shapes, the radially inner ends of the teeth may be joined by a radius. In any of the above described arrangements each pair of circumferentially adjacent teeth and associated slot may define a rectangle, a square or a triangle. The teeth in any of the above described arrangements may define sharp corners, e.g. a rectangle, a square or a triangle or smooth corners, e.g. an ellipse or a radius. The edges of the teeth in any of the above arrangements may be sharp, chamfered or curved.

Figure 10 shows a longitudinal cross-section through a rich burn fuel injector 56. The rich bum fuel injector 56 comprises a fuel feed arm and a fuel injector head 80. The fuel injector head 80 comprises an airblast fuel injector. The airblast fuel injector has, in order from radially inner to outer, a coaxial arrangement of an inner swirler air passage 82, a fuel passage 84, an intermediate air swirler passage 86 and an outer air swirler passage 88. The swirling air passing through the passages 82, 86, 88 of the fuel injector head 80 is high pressure and high velocity air derived from the high pressure compressor 14. Each swirler passage 82, 86, 88 has a respective swirler 92, 94 which swirls the air flow through that passage.

Figure 11 shows a longitudinal cross-section through a lean burn fuel injector 156. The lean burn fuel injector 156 comprises a fuel feed arm and a fuel injector head 180. The fuel injector head 180 has a coaxial arrangement of an inner pilot airblast fuel injector and an outer mains airblast fuel injector. The pilot airblast fuel injector has, in order from radially inner to outer, a coaxial arrangement of a pilot inner swirler air passage 182, a pilot fuel passage 184, and a pilot outer air swirler passage 186. The mains airblast fuel injector has, in order from radially inner to outer, a coaxial arrangement of a mains inner swirler air passage 188, a mains fuel passage 190, and a mains outer air swirler passage 192. An intermediate air swirler passage 194 is sandwiched between the outer air swirler passage 186 of the pilot airblast fuel injector and the inner swirler air passage 188 of the mains airblast fuel injector. The swirling air passing through the passages 182, 186, 188, 192, 194 of the fuel injector head 180 is high pressure and high velocity air derived from the high pressure compressor 14. Each swirler passage 182, 186, 188, 192, 194 has a respective swirler 196, 198, 200, 202, 204 which swirls the airflow through that passage.

Each of the fuel injector heads 80, 180 may have a portion which has a part spherical surface so to abut and seal against the inner surface of the second portion 62 of the associated seal 58. Alternatively, each of the fuel injector heads 80, 180 may have a portion which has a cylindrical surface so to abut and seal against the inner surface of the second portion 62 of the associated seal 58.

Although the present disclosure has been described with reference to an annular combustion chamber it is equally applicable to a tubular combustion chamber comprising an upstream end wall and an annular wall and the upstream end wall has a single aperture with a fuel injector and a seal or to a can annular combustion chamber arrangement comprising a plurality of circumferentially spaced tubular combustion chambers each comprising an upstream end wall and an annular wall and the upstream end wall of each tubular combustion chamber has a single aperture with a fuel injector and a seal.

The combustion chamber may be a gas turbine engine combustion chamber.

The advantage of the present disclosure is that each seal produces better mixing between the coolant, air, and the fuel and air mixture from the associated fuel injector to reduce emissions produced in the combustion chamber. In each of the different seal arrangements the seal enhances mixing of the coolant, air, from the coolant apertures with the fuel and air mixture from the associated fuel injector by creating a pressure differential between the inner surface of the seal and the outer surface of the seal and by providing the teeth and/or slots at the downstream end of the seal which create small scale turbulent air flow structures.

It will be understood that the invention is not limited to the embodiments abovedescribed 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

1. A combustion chamber comprising an upstream end wall, at least one annular wall, at least one fuel injector and at least one seal, the at least one annular wall being secured to the upstream end wall, the upstream end wall having at least one aperture, each fuel injector being arranged in a corresponding one of the apertures in the upstream end wall, each seal being arranged in a corresponding one of the apertures in the upstream end wall and around the corresponding one of the fuel injectors, each seal having an upstream end, a downstream end, an inner surface facing the corresponding one of the fuel injectors and an outer surface facing away from the corresponding one of the fuel injectors, each seal abutting the corresponding one of the fuel injectors, the downstream end of each seal increasing in diameter in a downstream direction, the downstream end of each seal being arranged at an angle greater than 0° and less than 50° to the axis of the seal, the downstream end of each seal having a plurality of circumferentially spaced teeth, the teeth at the downstream end of each seal extending radially outwardly and axially away from the upstream end of the seal.

2. A combustion chamber as claimed in claim 1 wherein the downstream end of each seal being arranged at an angle less than 45° to the axis of the seal.

3. A combustion chamber as claimed in claim 1 or claim 2 wherein the downstream end of each seal being arranged at an angle less than 40° to the axis of the seal.

4. A combustion chamber as claimed in claim 1, claim 2 or claim 3 wherein the downstream end of each seal being arranged at an angle less than 30° to the axis of the seal.

5. A combustion chamber as claimed in any of claims 1 to 4 wherein the downstream end of each seal may be arranged at an angle less than 20° to the axis of the seal.

6. A combustion chamber as claimed in any of claims 1 to 5 wherein the downstream end of each seal being arranged at an angle less than 10° to the axis of the seal.

7. A combustion chamber as claimed in any of claims 1 to 6 wherein the teeth not being angled.

8. A combustion chamber as claimed in any of claims 1 to 6 wherein the teeth being angled with a tangential, or circumferential, component.

9. A combustion chamber as claimed in claim 8 wherein the teeth being angled with a tangential, or circumferential, component between and including 20° and 60°.

10. A combustion chamber as claimed in any of claims 1 to 9 wherein he downstream end of each seal being arcuate.

11. A combustion chamber as claimed in any of claims 1 to 10 wherein each seal having a plurality of coolant apertures extending there-through, each coolant aperture having an inlet in the inner surface and an outlet in the outer surface of the seal, the coolant apertures being arranged upstream of the downstream end of the seal, the outlet of each coolant aperture being axially spaced in a downstream direction from its inlet, the outlet of each coolant aperture being radially spaced from its inlet.

12. A combustion chamber as claimed in any of claims 1 to 11 wherein each seal having a first portion, a second portion and a third portion, the second portion abutting the corresponding one of the fuel injectors, the third portion being arranged at the downstream end of the seal, the third portion increasing in diameter in a downstream direction, the first portion being arranged upstream of the second portion, the first portion having a plurality of coolant apertures extending there-through, the coolant apertures extending through the first portion with axial and radial components.

13. A combustion chamber as claimed in claim 12 wherein each seal comprising a substantially cylindrical first portion, a substantially cylindrical second portion and a frustoconical third portion or a bell mouth third portion.

14. A combustion chamber as claimed in claim 13 wherein the first portion of each seal having an inner diameter greater than the inner diameter of the second portion of that seal.

15. A combustion chamber as claimed in claim 12, claim 13 or claim 14 wherein the axes of the coolant apertures in first portion of each seal being arranged to intersect the third portion of the seal to direct coolant onto the third portion of the seal.

16. A combustion chamber as claimed in any of claims 12 to 15 wherein the third portion of each seal having a plurality of circumferentially spaced radially and axially extending teeth at its downstream end at the maximum diameter of the third portion.

17. A combustion chamber as claimed in any of claims 12 to 16 wherein each seal comprising a fourth portion, the fourth portion of each seal being secured to the upstream end wall such that the seal may move radially with respect to the axis of the corresponding aperture in the upstream end wall.

18. A combustion chamber as claimed in any of claims 1 to 17 wherein each seal being circular in cross-section.

19. A combustion chamber as claimed in any of claims 1 to 18 wherein the combustion chamber being an annular combustion chamber comprising an annular upstream end wall, a radially inner annular wall, a radially outer annular wall, a plurality of fuel injectors and a plurality of seals and the annular upstream end wall having a plurality of apertures.

20. A combustion chamber as claimed in any of claims 1 to 19 wherein the fuel injector being a rich burn fuel injector or a lean bum fuel injector.

21. A combustion chamber as claimed in any of claims 1 to 20 wherein the combustion chamber being a gas turbine engine combustion chamber.

22. A combustion chamber as claimed in claim 21 wherein the gas turbine engine being an industrial gas turbine engine, an automotive gas turbine engine, a marine gas turbine engine or an aero gas turbine engine.

23. A combustion chamber as claimed in claim 22 wherein the aero gas turbine engine being a turbofan gas turbine engine, a turbojet gas turbine engine, a turbo-propeller gas turbine engine or a turbo-shaft gas turbine engine.

24. A combustion chamber fuel injector seal having a downstream end, the downstream end of the seal increasing in diameter in a downstream direction, the seal having an upstream end, a downstream end, an inner surface facing the fuel injector and an outer surface facing away from the fuel injector, each seal being arranged to abut the fuel injector, the downstream end of the seal increasing in diameter in a downstream direction, the downstream end of the seal being arranged at an angle greater than 0° and less than 50° to the axis of the seal, the downstream end of the seal having a plurality of circumferentially spaced teeth, the teeth at the downstream end of the seal extending radially outwardly and axially away from the upstream end of the seal.

25. A combustion chamber fuel injector seal as claimed in claim 24 wherein the downstream end of the seal being arranged at an angle less than 45° to the axis of the seal.

26. A combustion chamber fuel injector seal as claimed in claim 24 or claim 25 wherein the downstream end of the seal being arranged at an angle less than 40° to the axis of the seal.

27. A combustion chamber fuel injector seal as claimed in claim 24, claim 25 or claim 26 wherein the downstream end of the seal being arranged at an angle less than 30° to the axis of the seal.

28. A combustion chamber fuel injector seal as claimed in claim 24, claim 25, claim 26 or claim 27 wherein the downstream end of the seal being arranged at an angle less than 20° to the axis of the seal.

29. A combustion chamber fuel injector seal as claimed in claim 24, claim 25, claim 26, claim 27 or claim 28 wherein the downstream end of the seal being arranged at an angle less than 10° to the axis of the seal.

30. A combustion chamber fuel injector seal as claimed in any of claims 24 to 29 wherein the teeth not being angled.

31. A combustion chamber fuel injector seal as claimed in any of claims 24 to claim 29 wherein he teeth being angled with a tangential, or circumferential, component.

32. A combustion chamber fuel injector seal as claimed in claim 31 wherein the teeth being angled with a tangential, or circumferential, component between and including 20° and 60°.

33. A combustion chamber fuel injector seal as claimed in any of claims 24 to claim 32 wherein the downstream end of the seal being arcuate.

34. A combustion chamber fuel injector seal as claimed in any of claims 24 to

33 wherein the seal having a plurality of coolant apertures extending therethrough, each coolant aperture having an inlet in the inner surface and an outlet in the outer surface of the seal, the coolant apertures being arranged upstream of the downstream end of the seal, the outlet of each coolant aperture being axially spaced in a downstream direction from its inlet, the outlet of each coolant aperture being radially spaced from its inlet.

35. A combustion chamber fuel injector seal as claimed in any of claims 24 to

34 wherein the seal having a first portion, a second portion and a third portion, the second portion being arranged to abut the fuel injector, the third portion being arranged at the downstream end of the seal, the third portion increasing in diameter in a downstream direction, the first portion being arranged upstream of the second portion, the first portion having a plurality of coolant apertures extending there-through, the coolant apertures extending through the first portion with axial and radial components.

36. A combustion chamber fuel injector seal as claimed in claim 35 wherein the seal comprising a substantially cylindrical first portion, a substantially cylindrical second portion and a frustoconical third portion or a bell mouth third portion.

37. A combustion chamber fuel injector seal as claimed in claim 35 or claim 36 wherein the first portion of the seal having an inner diameter greater than the inner diameter of the second portion of the seal.

38. A combustion chamber fuel injector seal as claimed in claim 35, claim 36 or claim 37 wherein the axes of the coolant apertures in first portion of the seal being arranged to intersect the third portion of the seal to direct coolant onto the third portion of the seal.

39. A combustion chamber fuel injector seal as claimed in claim 35, claim 36, claim 37 or claim 38 wherein the third portion of the seal having a plurality of circumferentially spaced radially and axially extending teeth at its downstream end at the maximum diameter of the third portion.

40. A combustion chamber fuel injector seal as claimed in any of claims 24 to 34 wherein the seal comprising a fourth portion, the fourth portion of the seal being securable to an upstream end wall such that the seal may move radially with respect to the axis of an aperture in the upstream end wall.

41. A combustion chamber fuel injector seal as claimed in any of claims 24 to 40 wherein the seal being circular in cross-section