Fuel manifold and fuel injector arrangement

A fuel manifold and fuel injector arrangement comprises an annular fuel manifold and a plurality of fuel injectors. Each fuel injector comprises a fuel injector head and a hollow fuel feed arm. Each fuel injector has a pipe to supply fuel to the fuel injector head. The pipe extends from the fuel feed arm and through a corresponding aperture in the casing. The annular fuel manifold is arranged around the casing and the annular fuel manifold comprises a plurality of connectors. Each connector has a socket aligned with a corresponding aperture in the casing. Each pipe has a plug arranged to be radially slidably mounted in the socket of the corresponding connector of the annular fuel manifold to allow relative radial movement between the casing and the annular fuel manifold.

FIELD OF THE INVENTION

The present disclosure relates to a fuel manifold and a fuel injector arrangement and in particular relates to a fuel manifold and fuel injector arrangement for a gas turbine engine.

BACKGROUND TO THE INVENTION

Gas turbine engines have an arrangement of fuel injectors to supply fuel into the combustion chamber of the gas turbine engine and have a fuel manifold to supply fuel to the fuel injectors. In operation the fuel injectors are subjected to relatively high temperatures due to their proximity to the combustion chamber whereas the fuel manifold is subjected to relatively cold temperatures due to the relatively cold fuel within the fuel manifold which is supplied from the fuel manifold to the fuel injectors.

Thermal management of the fuel manifold and fuel injectors is required.

Fuel injectors have been provided with flexible internal fuel pipes or have been provided with internal sliding joints. Fuel injectors with flexible internal fuel pipes are bulky and it is difficult or impossible to inspect fuel injectors with flexible internal fuel pipes to determine whether they have failed. Fuel injectors with internal sliding joints invariably leak internally and the leakage of fuel leads to coking and gumming of the fuel with the possibility of deformation of the fuel injector and again it is difficult or impossible to inspect fuel injectors with internal sliding joints to determine whether they have failed.

Fuel manifolds have been made flexible by constructing the fuel manifold using fibre reinforced polymer pipes or by constructing portions of the fuel manifold from curved metal pipes, called pigtails. Fuel manifolds constructed from fibre reinforced polymer pipes are bulky and are difficult to fire proof. Fuel manifolds constructed from curved metal pipes are fragile, susceptible to handling damage, suffer from vibration and require extensive use of clips, or other types of fasteners, to secure the metal pipes to the gas turbine engine casing to reduce vibration.

Therefore the present invention seeks to provide a novel fuel manifold and fuel injector arrangement which reduces or overcomes the above mentioned problem.

STATEMENTS OF INVENTION

Accordingly the present disclosure provides a fuel manifold and fuel injector arrangement for supplying fuel to at least one combustion chamber comprising an annular combustion chamber casing arranged around the at least one combustion chamber, an annular fuel manifold and a plurality of fuel injectors,each fuel injector comprising a fuel injector head and a hollow fuel feed arm, each fuel feed arm having an end remote from the fuel injector head, the end of each fuel feed arm remote from the fuel injector head being secured to the casing, each fuel injector having a pipe to supply fuel to the fuel injector head, the pipe extending from the fuel feed arm and through a corresponding aperture in the casing,the annular fuel manifold being arranged around the casing, the annular fuel manifold comprising a plurality of connectors, each connector having a socket or a plug aligned with a corresponding aperture in the casing,each pipe having a plug or a socket arranged to be radially slidably mounted in the socket or the plug of the corresponding connector of the annular fuel manifold to allow relative radial movement between the casing and the annular fuel manifold.

Preferably each connector having a socket aligned with a corresponding aperture in the casing and each pipe having a plug arranged to be radially slidably mounted in the socket of the corresponding connector of the annular fuel manifold.

Each plug may be generally cylindrical and the socket being circular in cross-section.

Each plug may have at least one annular groove and each annular groove having an O-ring seal.

Each O-ring seal may comprise a polymeric material.

The annular fuel manifold may comprise a plurality of segments.

The annular fuel manifold may be arranged in a plane containing the apertures in the casing and each connector may be arranged to extend radially from the annular manifold. Each connector may be integral with the annular fuel manifold.

The annular fuel manifold may be arranged in a plane parallel to and spaced axially from the apertures in the casing and each connector extends axially and radially from the annular fuel manifold. Each connector may be separate from the annular fuel manifold. Each connector may comprise a plug arranged to be mounted in a socket in the annular fuel manifold. The plug of each connector may extend axially and the socket of each connector extends radially. Each connector may be L-shaped. The plug of each connector may have at least one annular groove and each annular groove having an O-ring seal. Each O-ring seal may comprise a polymeric material.

Each pipe may have a second plug arranged to be radially slidably mounted in a socket of the fuel feed arm to allow further relative radial movement between the casing and the annular fuel manifold. Each second plug may be generally cylindrical and the socket of the fuel feed arm being circular in cross-section. Each second plug may have at least one annular groove and each annular groove having an O-ring seal. Each O-ring seal may comprise a polymeric material.

The end of each fuel feed arm remote from the fuel injector head may have a flange which is secured to the casing. The flange may be arranged radially outside the casing or radially inside the casing.

DETAILED DESCRIPTION

A turbofan gas turbine engine10, as shown inFIG. 1, comprises in flow series an intake11, a fan12, an intermediate pressure compressor13, a high pressure compressor14, a combustion chamber15, a high pressure turbine16, an intermediate pressure turbine17, a low pressure turbine18and an exhaust19. The high pressure turbine16is arranged to drive the high pressure compressor14via a first shaft26. The intermediate pressure turbine17is arranged to drive the intermediate pressure compressor13via a second shaft28and the low pressure turbine18is arranged to drive the fan12via a third shaft30. In operation air flows into the intake11and is compressed by the fan12. A first portion of the air flows through, and is compressed by, the intermediate pressure compressor13and the high pressure compressor14and is supplied to the combustion chamber15. Fuel is injected into the combustion chamber15and is burnt in the air to produce hot exhaust gases which flow through, and drive, the high pressure turbine16, the intermediate pressure turbine17and the low pressure turbine18. The hot exhaust gases leaving the low pressure turbine18flow through the exhaust19to provide propulsive thrust. A second portion of the air bypasses the main engine to provide propulsive thrust.

The combustion chamber15, as shown more clearly inFIG. 2, is an annular combustion chamber and comprises a radially inner annular wall structure40, a radially outer annular wall structure42and an upstream end wall structure44. The radially inner annular wall structure40comprises a first annular wall46. The radially outer annular wall structure42comprises a second annular wall48. The upstream end of the first annular wall46is secured to the upstream end wall structure44and the upstream end of the second annular wall48is secured to the upstream end wall structure44. In this example the radially inner annular wall structure40also comprises a number of tiles52secured to the first annular wall46and the radially outer annular wall structure42also comprises a number of tiles52secured to the second annular wall48. The upstream end wall structure44has a plurality of circumferentially spaced apertures50and each aperture50has a respective one of a plurality of fuel injectors58located therein. The apertures50are equi-angularly spaced around the upstream annular wall54and the apertures50are generally circular. The fuel injectors58are arranged to supply fuel into the annular combustion chamber15during operation of the gas turbine engine10. The annular combustion chamber15has an axis which is coaxial with the axis X-X of the turbofan gas turbine engine10.

A fuel manifold and fuel injector arrangement54for a combustion chamber15according to the present disclosure is shown more clearly inFIGS. 3 to 6. The combustion chamber15is an annular combustion chamber and an annular combustion chamber casing56is arranged generally coaxially around the annular combustion chamber15and coaxially with the axis X-X of the turbofan gas turbine engine10. The annular combustion chamber casing56has a flange55at an upstream end and a flange57at a downstream end. The flanges55and57are fastened to an adjacent compressor casing (not shown) and an adjacent turbine casing (not shown) respectively via suitable fasteners, e.g. nuts, bolts and washers. A plurality of circumferentially spaced fuel injectors58are arranged to supply fuel into the annular combustion chamber15and a fuel manifold64is arranged to supply fuel to each of the fuel injectors58. Each fuel injector58comprises a fuel feed arm66and a fuel injector head60. The fuel injector head60of each fuel injector58is located in the respective aperture50in the upstream end wall structure44of the combustion chamber15. Each fuel feed arm66extends through a corresponding one of a plurality of circumferentially spaced apertures68in the annular combustion chamber casing56. Each fuel feed arm66has an associated sealing plate, or flange,70which is secured onto the annular combustion chamber casing56by suitable fasteners, e.g. bolts. The fuel injectors58and apertures68are equi-circumferentially spaced around the annular combustion chamber casing56. Each fuel feed arm66is hollow and is arranged to supply fuel from the fuel manifold64to its associated fuel injector head60.

The fuel manifold and fuel injector arrangement54comprises the annular fuel manifold64and the plurality of fuel injectors58. Each fuel injector58comprises a fuel injector head60and a hollow fuel feed arm66, as mentioned previously. Each fuel feed arm66is open at an end69remote from the fuel injector head60and the end69of each fuel feed arm66remote from the fuel injector head60is secured to the annular combustion chamber casing56by its flange70. Each fuel injector58has a pipe72to supply fuel to the fuel injector head60and the pipe72extends through the fuel feed arm66from the fuel injector head60to the end69of the fuel feed arm68remote from the fuel injector head60. The pipe72also extends out of and away from the fuel feed arm66and through a corresponding aperture68in the annular combustion chamber casing56. The annular fuel manifold64is arranged around the annular combustion chamber casing56and the annular fuel manifold64comprises a plurality of connectors74. Each connector74is integral, unitary or one piece, with the annular fuel manifold64. Each connector74has a socket76aligned with a corresponding aperture68in the annular combustion chamber casing56and the radially outer end of each pipe72has a plug78arranged to be radially slidably mounted in the socket76of the corresponding connector74of the annular fuel manifold64to allow relative radial movement between the annular combustion chamber casing56and the annular fuel manifold64. Each plug78is generally cylindrical and has a cylindrical outer surface and the corresponding socket76is also circular in cross-section and has a cylindrical inner surface to match and receive the plug78. Each plug78has at least one annular groove80on its cylindrical outer surface and each annular groove80has an O-ring seal82. Each O-ring seal82comprises a polymeric material or other suitable material which is resilient to form a seal. The O-ring seals82are preferably resistant to corrosion by the fuel. The annular fuel manifold64comprises a plurality of segments84, seeFIG. 4, to enable the annular fuel manifold64to be assembled. The number of segments84is determined by the radius of the annular combustion chamber casing56compared to the radius of the annular fuel manifold64. The number of segments84may be equal to the number of fuel injectors58and in this example each segment84comprises one connector74.

As shown inFIGS. 4, 5 and 6the annular fuel manifold64is arranged in a plane P containing the apertures68in the annular combustion chamber casing56and in particular the annular fuel manifold64is arranged in a plane P containing the axes of the apertures68in the annular combustion chamber casing56. Each connector74is arranged to extend radially from the annular fuel manifold64. The plane P is a plane arranged perpendicular to the axis X-X of the turbofan gas turbine engine10.FIG. 5is a cross-sectional view of the fuel manifold and fuel injector arrangement54along plane P. Thus, the axis of each cylindrical socket76is arranged generally radially in the plane P and the axis of each cylindrical plug78is arranged generally radially in the plane P. However, there may be some movement away from this general alignment.

A further fuel manifold and fuel injector arrangement154comprises an annular fuel manifold164and a plurality of fuel injectors158as shown inFIGS. 7 and 8, is similar to that shown inFIGS. 5 and 6. InFIGS. 5 and 6each fuel injector158has a pipe172to supply fuel to the fuel feed arm166and the fuel feed arm166has a fuel duct167extending there-through to supply fuel to the fuel injector head160. The pipe172also extends out of and away from the fuel feed arm166and through a corresponding aperture68in the annular combustion chamber casing56. The annular fuel manifold164is arranged around the annular combustion chamber casing56and the annular fuel manifold164comprises a plurality of connectors174. Each connector174is integral, unitary or one piece, with the annular fuel manifold164. Each connector174has a socket176aligned with a corresponding aperture68in the annular combustion chamber casing56and the radially outer end of each pipe172has a plug178arranged to be radially slidably mounted in a socket176of corresponding connector174of the annular fuel manifold164to allow relative radial movement between the annular combustion chamber casing56and the annular fuel manifold164. Each plug178is generally cylindrical and has a cylindrical outer surface and the corresponding socket176is also circular in cross-section and has a cylindrical inner surface to match and receive the plug178. Each plug178has at least one annular groove180on its outer surface and each annular groove180has an O-ring seal182. Each O-ring seal182comprises a polymeric material or other suitable material which is resilient to form a seal and is resistant to corrosion by the fuel. The annular fuel manifold164also comprises a plurality of segments184, similar to those inFIG. 4. The number of segments is determined by the radius of the annular combustion chamber casing56compared to the radius of the annular fuel manifold164. The number of segments may be equal to the number of fuel injectors58and each segment would comprise one connector174.

The radially inner end of each pipe172has a second plug186arranged to be radially slidably mounted in a socket188in the end169of the fuel feed arm166to allow further relative radial movement between the annular combustion chamber casing56and the annular fuel manifold164. Each second plug186is generally cylindrical and has a cylindrical outer surface and the socket188of the fuel feed arm166is circular in cross-section and has a cylindrical inner surface to match and receive the plug186. Each second plug186has at least one annular groove190on its outer surface and each annular groove190has an O-ring seal192. Each O-ring seal192comprises a polymeric material or other suitable material which is resilient to form a seal and is resistant to corrosion by the fuel.

The annular fuel manifold164is also arranged in a plane P containing the apertures68in the annular combustion chamber casing56and in particular the annular fuel manifold164is arranged in a plane P containing the axes of the apertures68in the annular combustion chamber casing56. Each connector174is arranged to extend radially from the annular fuel manifold164. The plane P is a plane arranged perpendicular to the axis X-X of the turbofan gas turbine engine10.FIG. 7is a cross-sectional view of the fuel manifold and fuel injector arrangement154along plane P. Thus, the axis of each cylindrical socket176is arranged generally radially in the plane P and the axis of each cylindrical plug178is arranged generally radially in the plane P. Also, the axis of each cylindrical socket188is arranged generally radially in the plane P and the axis of each cylindrical plug186is arranged generally radially in the plane P. However, there may be some movement away from this general alignment.

The fuel manifold and fuel injector arrangement154provides pipes172which have plugs178and186at both ends of the pipes172to connect the fuel injectors158to the annular fuel manifold164. The pipes172provide resilience and allow some angular mismatch between the fuel feed arms166of the fuel injectors158and the connectors174on the annular fuel manifold to be accommodated during assembly of the fuel manifold and fuel injector arrangement154and also enables the annular fuel manifold164to have fewer segments.

Another fuel manifold and fuel injector arrangement154comprises an annular fuel manifold264and a plurality of fuel injectors (not shown) as shown inFIG. 9, is similar to that shown inFIGS. 5 and 6. InFIG. 9each fuel injector (not shown) has a pipe272to supply fuel to the fuel injector (not shown). Each pipe272extends from the remote end of the fuel feed arm through a corresponding aperture68in the annular combustion chamber casing56. The annular fuel manifold264is arranged around the annular combustion chamber casing56and the annular fuel manifold264comprises a plurality of connectors274. Each connector274has a socket276aligned with a corresponding aperture68in the annular combustion chamber casing56and the radially outer end of each pipe272has a plug278arranged to be radially slidably mounted in a socket276of the corresponding connector274of the annular fuel manifold264to allow relative radial movement between the annular combustion chamber casing56and the annular fuel manifold264. Each plug278is generally cylindrical and has a cylindrical outer surface and the corresponding socket276is also circular in cross-section and has a cylindrical inner surface to match and receive the plug278. Each plug278has at least one annular groove280on its cylindrical outer surface and each annular groove280has an O-ring seal282. Each O-ring seal282comprises a polymeric material or other suitable material which is resilient to form a seal and is resistant to corrosion by the fuel. The annular fuel manifold264also comprises a plurality of segments, similar to those inFIG. 4. The number of segments is determined by the radius of the annular combustion chamber casing56compared to the radius of the annular fuel manifold264. The number of segments may be equal to the number of fuel injectors58and each segment would comprise one connector274.

The annular fuel manifold264is arranged in a plane R parallel to and spaced axially from the apertures68in the annular combustion chamber casing56and each connector274extends axially and radially from the annular fuel manifold264. In particular the annular fuel manifold264is arranged in a plane R parallel and spaced axially from the plane Q containing the axes of the apertures68in the annular combustion chamber casing56. Each connector274is separate from the annular fuel manifold264. Each connector274comprises a plug284arranged to be mounted in a socket286in the annular fuel manifold264. The plug284of each connector274extends axially and the socket276of each connector274extends radially and thus each connector274is substantially L-shaped. The plug284of each connector274has a generally cylindrical outer surface and the outer surface of each plug284has at least one annular groove288and each annular groove288has an O-ring seal290. Each socket286is generally cylindrical and has a cylindrical inner surface to match and receive the corresponding plug284. Each O-ring seal290comprises a polymeric material or other suitable material which is resilient to form a seal and is resistant to corrosion by the fuel. Each connector274is secured to the annular fuel manifold264by securing the flange on each connector274to a corresponding flange on the annular fuel manifold264using suitable fasteners, e.g. nuts and bolts.

The fuel manifold and fuel injector arrangement254provides L-shaped connectors274which are separate from the annular fuel manifold264and positions the annular fuel manifold264in a plane spaced axially from the plane of the apertures68in the annular combustion chamber casing56. This arrangement enables easier assembly of the fuel manifold and fuel injector arrangement254. Alternatively, each connector274comprises a socket arranged to be mounted on/or receive a plug on the annular fuel manifold264.

However it is possible that each connector274may be integral with the annular fuel manifold264.

Although in each of the fuel manifold and fuel injector arrangements described above the annular fuel manifold comprises a plurality of connectors integral with the fuel manifold it is equally possible for each of these fuel manifold and fuel injector arrangements to comprise a plurality of separate connectors and arrange the adjacent connectors to be interconnected by separate fuel pipes.

In each of the fuel manifold and fuel injector arrangements described above where a single annular groove and corresponding O-ring seal is provided, it is equally possible to provide two or more annular grooves each of which has an O-ring seal to provide higher integrity sealing. The O-ring seals may be circular in cross-section or may be rectangular, square, in cross-section.

In addition a hard anti-extrusion ring may be included in the plug and socket arrangements in each of the fuel manifold and fuel injector arrangements described above to provide higher integrity sealing.

Although the present disclosure has referred to cylindrical plug and socket arrangements it may be possible to provide other suitable types of plug and socket for example the plug and socket may be rectangular outer and inner surfaces respectively or the plug may have a spherical outer surface and the socket may have a cylindrical inner surface to allow lateral movement.

In the present disclosure the joint, connection, between the fuel manifold, the annular fuel manifold, and the fuel injectors is achieved using junctions, connections, where the mating parts are able to move, slide, radially relative to each other. Variations in the diameter of the annular combustion chamber casing and/or the diameter of the annular fuel manifold for whatever reason are accommodated by radial movement, radial sliding, of the mating parts, e.g. the plug and socket, and concentricity of the annular combustion chamber casing and annular fuel manifold may be maintained. The variations in diameter of the annular combustion chamber casing and the annular fuel manifold may be due to differential thermal responses and/or manufacturing tolerances. The fuel manifold and fuel injector arrangement accommodates these differences at a single point for each fuel injector and thus reduces the number of sealing positions required for assembly of the fuel manifold and fuel injector assembly. The present disclosure dispenses with the need for the curved metal pipes, pigtails, and their associated clips and simplifies assembly and reduces weight. The present disclosure also increases vibration damping and improves inspectability.

Although the present disclosure has referred to an annular combustion chamber having a plurality of fuel injectors it is equally applicable to a tubo-annular combustion chamber or to a plurality of tubular combustion chambers each of which has a single fuel injector.

Although the present disclosure has been described with reference to the use of a plug on the pipe and a socket in the connector it is equally possible to provide a plug on the connector and a socket on the pipe.

Although the end of each fuel feed arm remote from the fuel injector head has a flange which is secured to the annular combustion chamber casing on the radially inside of the annular combustion chamber casing, it is equally possible for the flange at the end of each fuel feed arm remote from the fuel injector head to be secured on the radially outside of the annular combustion chamber casing.

The gas turbine engine may be an aero gas turbine engine, a marine gas turbine engine, an industrial gas turbine engine or an automotive gas turbine engine. The aero gas turbine engine may be a turbofan gas turbine engine, a turboprop gas turbine engine, a turbojet gas turbine engine or a turboshaft gas turbine engine.