GB2588896A

GB2588896A - A beam seal fluid coupling assembly

Info

Publication number: GB2588896A
Application number: GB1916423.5A
Authority: GB
Inventors: Wilson Jonathan
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2019-11-12
Filing date: 2019-11-12
Publication date: 2021-05-19
Anticipated expiration: 2039-11-12
Also published as: GB201916423D0; GB2588896B

Abstract

A beam seal fluid coupling assembly 100 for a gas turbine engine (10, Figure 1) is provided. The beam seal fluid coupling assembly 100 comprises: a beam seal element (110, Figure 5); a first fluid conduit coupling component 103; and a second fluid conduit coupling component 104. The first and second fluid conduit coupling components 103, 104 are connectable to one another. The beam seal element 110 comprises an elongate section 112 defined by a circumferentially and longitudinally extending wall having a convoluted profile along the length of the elongate section 112 such that the elongate section is compressible; a lip seal 111 provided at a distal end of the beam seal element 110, the lip seal 111 extending from the wall in a radial direction; and an abutment surface 113 provided at an end of the elongate section 112 opposite the lip seal 111. The beam seal element 110 is providable between respective first and second mating surfaces 120, 121 of the first and second fluid conduit coupling components 103,104, such that the first mating surface 120 engages the abutment surface 113 of the beam seal element 110 and the second mating surface 121 engages the lip seal 111.

Description

A BEAM SEAL FLUID COUPLING ASSEMBLY

Technical field of the Disclosure

The present disclosure relates to a beam seal fluid coupling assembly, and particularly but not exclusively relates to a beam seal fluid coupling assembly comprising an elongate section with a convoluted profile, such that the elongate section is compressible.

Background of the Disclosure

Beam seals, also known as lip seals, are fluid coupling devices used in applications where high integrity is required. Beam seals are used across a range of fluid types such as fuel, oil, hydraulic fluid and air, to provide reliable sealing at high levels of pressure, e.g. up to 8000 psi. One such application is a gas turbine engine and beam seals are referred to for example in SAE Standard AS85421.

Typically, a beam seal coupling device comprises a male portion which is inserted into a female portion to form a mating surface at their juncture. A single nut rotating about the central axis of the device is used to provide the clamping force between the male and female portions, such that a fluid-tight seal is formed at the mating surface.

One problem with beam seals using a nut for fastening is that there is a variation in the torque level required to create an effective seal for different sizes of nut. When multiple beam seal devices of different size couplings are used on the same platform, there is the potential for incorrect assembly, which is undesirable.

Another problem with beam seals using a nut for fastening is that a secondary locking feature may be required to reduce the likelihood of the joint become loose.

Additionally, with recent advances in gas turbine technology, there is a desire for a coupling device that can tolerate higher pressures.

Accordingly, there is a need for improvements in the art of beam seals.

Summary of the Disclosure

According to a first aspect there is provided a beam seal fluid coupling assembly for a gas turbine engine comprising a beam seal element, a first fluid conduit coupling component, and a second fluid conduit coupling component; the first fluid conduit coupling component and the second fluid conduit coupling component being connectable to one another. The beam seal element comprises an elongate section defined by a circumferentially and longitudinally extending wall having a convoluted profile along the length of the elongate section such that the elongate section may be compressible; a lip seal provided at a distal end of the beam seal element, the lip seal extending from the wall in a direction with a radial component; and an abutment surface provided at an end of the elongate section opposite the lip seal, wherein the beam seal element is providable between respective first and second mating surfaces of the first and second fluid conduit coupling components, such that the first mating surface engages the abutment surface of the beam seal element and the second mating surface engages the lip seal.

The convoluted profile of the elongate section may be variable such that its compressibility may be better suited to the environment in which the beam seal fluid coupling assembly operates.

The convoluted profile may be able to expand or contract without breaking a fluid tight seal.

The convoluted profile may exert additional load on the seal coaxially with the fluid conduit such that the seal may be less likely to be broken.

The convoluted profile may be resiliently compressible. The fluid conduits may be of different diameters.

The first and second fluid conduit coupling components may each comprise a flange which extends radially.

The first and second fluid conduit coupling components may be joined by virtue of at least one bolt passing through the flanges of the first and second fluid conduit coupling components.

The beam seal fluid coupling assembly may further comprise a fluid-restricting component insertable within the beam seal fluid coupling assembly in order to restrict the fluid flow through the beam seal fluid coupling assembly.

The fluid-restricting component may comprise an opening to permit flow therethrough.

The fluid-restricting component may prevent fluid flow through the beam seal fluid coupling assembly.

The fluid-restricting component may be providable between the lip seal of the beam seal element and the mating surface of the second fluid conduit coupling component.

The second fluid conduit coupling component may be connectable to a second fluid conduit. The beam seal element may be connectable to a first fluid conduit.

The first fluid coupling component may be connectable to a first fluid conduit.

The abutment surface of the beam seal element may be a further lip seal extending from the wall in a direction with a radial component.

The convoluted profile may comprise at least one convolution, the or each convolution may comprise a diagonal section and an adjacent straight section.

According to another aspect, there is provided a gas turbine engine for an aircraft, wherein the gas turbine engine may comprise an engine core which may comprise a turbine, a compressor, and a core shaft which may connect the turbine to the compressor; a fan which may be located upstream of the engine core, the fan may comprise a plurality of fan blades; and the beam seal fluid coupling assembly.

The gas turbine engine may further comprise: a gearbox that may receive an input from the core shaft and may output drive to the fan so as to drive the fan at a lower rotational speed than the core shaft.

The turbine may be a first turbine, the compressor may be a first compressor, and the core shaft may be a first core shaft; the engine core may further comprise a second turbine, a second compressor, and a second core shaft which may connect the second turbine to the second compressor; and the second turbine, second compressor, and second core shaft may be arranged to rotate at a higher rotational speed than the first core shaft.

As noted elsewhere herein, the present disclosure may relate to a gas turbine engine. Such a gas turbine engine may comprise an engine core comprising a turbine, a combustor, a compressor, and a core shaft connecting the turbine to the compressor. Such a gas turbine engine may comprise a fan (having fan blades) located upstream of the engine core.

Arrangements of the present disclosure may be particularly, although not exclusively, beneficial for fans that are driven via a gearbox. Accordingly, the gas turbine engine may comprise an optional gearbox that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft. The input to the gearbox may be directly from the core shaft, or indirectly from the core shaft, for example via a spur shaft and/or gear. The core shaft may rigidly connect the turbine and the compressor, such that the turbine and compressor rotate at the same speed (with the fan rotating at a lower speed).

The gas turbine engine as described and/or claimed herein may have any suitable general architecture. For example, the gas turbine engine may have any desired number of shafts that connect turbines and compressors, for example one, two or three shafts. Purely by way of example, the turbine connected to the core shaft may be a first turbine, the compressor connected to the core shaft may be a first compressor, and the core shaft may be a first core shaft. The engine core may further comprise a second turbine, a second compressor, and a second core shaft connecting the second turbine to the second compressor. The second turbine, second compressor, and second core shaft may be arranged to rotate at a higher rotational speed than the first core shaft.

In such an arrangement, the second compressor may be positioned axially downstream of the first compressor. The second compressor may be arranged to receive (for example directly receive, for example via a generally annular duct) flow from the first compressor.

The gearbox may be arranged to be driven by the core shaft that is configured to rotate (for example in use) at the lowest rotational speed (for example the first core shaft in the example above). For example, the gearbox may be arranged to be driven only by the core shaft that is configured to rotate (for example in use) at the lowest rotational speed (for example only be the first core shaft, and not the second core shaft, in the example above).

Alternatively, the gearbox may be arranged to be driven by any one or more shafts, for example the first and/or second shafts in the example above.

The gearbox may be a reduction gearbox (in that the output to the fan is a lower rotational rate than the input from the core shaft). Any type of gearbox may be used. For example, the gearbox may be a "planetary" or "star" gearbox, as described in more detail elsewhere herein. The gearbox may have any desired reduction ratio (defined as the rotational speed of the input shaft divided by the rotational speed of the output shaft), for example greater than 2.5, for example in the range of from 3 to 4.2, or 3.2 to 3.8, for example on the order of or at least 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1 or 4.2. The gear ratio may be, for example, between any two of the values in the previous sentence. Purely by way of example, the gearbox may be a "star" gearbox having a ratio in the range of from 3.1 or 3.2 to 3.8. In some arrangements, the gear ratio may be outside these ranges.

In any gas turbine engine as described and/or claimed herein, a combustor may be provided axially downstream of the fan and compressor(s). For example, the combustor may be directly downstream of (for example at the exit of) the second compressor, where a second compressor is provided. By way of further example, the flow at the exit to the combustor may be provided to the inlet of the second turbine, where a second turbine is provided. The combustor may be provided upstream of the turbine(s).

The or each compressor (for example the first compressor and second compressor as described above) may comprise any number of stages, for example multiple stages. Each stage may comprise a row of rotor blades and a row of stator vanes, which may be variable stator vanes (in that their angle of incidence may be variable). The row of rotor blades and the row of stator vanes may be axially offset from each other.

The or each turbine (for example the first turbine and second turbine as described above) may comprise any number of stages, for example multiple stages. Each stage may comprise a row of rotor blades and a row of stator vanes. The row of rotor blades and the row of stator vanes may be axially offset from each other.

Each fan blade may be defined as having a radial span extending from a root (or hub) at a radially inner gas-washed location, or 0% span position, to a tip at a 100% span position.

The ratio of the radius of the fan blade at the hub to the radius of the fan blade at the tip may be less than (or on the order of) any of: 0.4, 0.39, 0.38 0.37, 0.36, 0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, 0.27, 0.26, or 0.25. The ratio of the radius of the fan blade at the hub to the radius of the fan blade at the tip may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds), for example in the range of from 0.28 to 0.32. These ratios may commonly be referred to as the hub-to-tip ratio. The radius at the hub and the radius at the tip may both be measured at the leading edge (or axially forwardmost) part of the blade. The hub-to-tip ratio refers, of course, to the gas-washed portion of the fan blade, i.e. the portion radially outside any platform.

The radius of the fan may be measured between the engine centreline and the tip of a fan blade at its leading edge. The fan diameter (which may simply be twice the radius of the fan) may be greater than (or on the order of) any of: 220 cm, 230 cm, 240 cm, 250 cm (around 100 inches), 260 cm, 270 cm (around 105 inches), 280 cm (around 110 inches), 290 cm (around 115 inches), 300 cm (around 120 inches), 310 cm, 320 cm (around 125 inches), 330 cm (around 130 inches), 340 cm (around 135 inches), 350cm, 360cm (around 140 inches), 370 cm (around 145 inches), 380 (around 150 inches) cm, 390 cm (around 155 inches) ), 400 cm, 410 cm (around 160 inches) or 420 cm (around 165 inches). The fan diameter may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds), for example in the range of from 240 cm to 280 cm or 330 cm to 380 cm.

The rotational speed of the fan may vary in use. Generally, the rotational speed is lower for fans with a higher diameter. Purely by way of non-limitative example, the rotational speed of the fan at cruise conditions may be less than 2500 rpm, for example less than 2300 rpm. Purely by way of further non-limitative example, the rotational speed of the fan at cruise conditions for an engine having a fan diameter in the range of from 220 cm to 300 cm (for example 240 cm to 280 cm or 250 cm to 270 cm) may be in the range of from 1700 rpm to 2500 rpm, for example in the range of from 1800 rpm to 2300 rpm, for example in the range of from 1900 rpm to 2100 rpm. Purely by way of further non-limitative example, the rotational speed of the fan at cruise conditions for an engine having a fan diameter in the range of from 330 cm to 380 cm may be in the range of from 1200 rpm to 2000 rpm, for example in the range of from 1300 rpm to 1800 rpm, for example in the range of from 1400 rpm to 1800 rpm.

In use of the gas turbine engine, the fan (with associated fan blades) rotates about a rotational axis. This rotation results in the tip of the fan blade moving with a velocity Utip. The work done by the fan blades 13 on the flow results in an enthalpy rise dH of the flow. A fan tip loading may be defined as dH/Utip2, where dH is the enthalpy rise (for example the 1-D average enthalpy rise) across the fan and Utip is the (translational) velocity of the fan tip, for example at the leading edge of the tip (which may be defined as fan tip radius at leading edge multiplied by angular speed). The fan tip loading at cruise conditions may be greater than (or on the order of) any of: 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39 or 0.4 (all units in this paragraph being Jkg-1K-1/(ms-1)2). The fan tip loading may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds), for example in the range of from 0.28 to 0.31 or 0.29 to 0.3.

Gas turbine engines in accordance with the present disclosure may have any desired bypass ratio, where the bypass ratio is defined as the ratio of the mass flow rate of the flow through the bypass duct to the mass flow rate of the flow through the core at cruise conditions. In some arrangements the bypass ratio may be greater than (or on the order of) any of the following: 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5,17, 17.5, 18, 18.5, 19, 19.5 or 20. The bypass ratio may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds), for example in the range of from 13 to 16, or 13 to 15, or 13 to 14. The bypass duct may be substantially annular. The bypass duct may be radially outside the engine core. The radially outer surface of the bypass duct may be defined by a nacelle and/or a fan case.

The overall pressure ratio of a gas turbine engine as described and/or claimed herein may be defined as the ratio of the stagnation pressure upstream of the fan to the stagnation pressure at the exit of the highest pressure compressor (before entry into the combustor).

By way of non-limitative example, the overall pressure ratio of a gas turbine engine as described and/or claimed herein at cruise may be greater than (or on the order of) any of the following: 35, 40, 45, 50, 55, 60, 65, 70, 75. The overall pressure ratio may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds), for example in the range of from 50 to 70.

Specific thrust of an engine may be defined as the net thrust of the engine divided by the total mass flow through the engine. At cruise conditions, the specific thrust of an engine described and/or claimed herein may be less than (or on the order of) any of the following: 110 Nkg-1s, 105 N kg-1s, 100 Nkg-1s, 95 Nkg-1s, 90 Nkg-1s, 85 Nkg-1s or 80 Nkg-1s. The specific thrust may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds), for example in the range of from 80 Nkg-'s to 100 Nkg-'s, or 85 Nkals to 95 Nkg-'s. Such engines may be particularly efficient in comparison with conventional gas turbine engines.

A gas turbine engine as described and/or claimed herein may have any desired maximum thrust. Purely by way of non-limitative example, a gas turbine as described and/or claimed herein may be capable of producing a maximum thrust of at least (or on the order of) any of the following: 160kN, 170kN, 180kN, 190kN, 200kN, 250kN, 300kN, 350kN, 400kN, 450kN, 500kN, or 550kN. The maximum thrust may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds). Purely by way of example, a gas turbine as described and/or claimed herein may be capable of producing a maximum thrust in the range of from 330kN to 420 kN, for example 350kN to 400kN. The thrust referred to above may be the maximum net thrust at standard atmospheric conditions at sea level plus 15 degrees C (ambient pressure 101.3kPa, temperature 30 degrees C), with the engine static.

In use, the temperature of the flow at the entry to the high pressure turbine may be particularly high. This temperature, which may be referred to as TET, may be measured at the exit to the combustor, for example immediately upstream of the first turbine vane, which itself may be referred to as a nozzle guide vane. At cruise, the TET may be at least (or on the order of) any of the following: 1400K, 1450K, 1500K, 1550K, 1600K or 1650K. The TET at cruise may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds). The maximum TET in use of the engine may be, for example, at least (or on the order of) any of the following: 1700K, 1750K, 1800K, 1850K, 1900K, 1950K or 2000K. The maximum TET may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds), for example in the range of from 1800K to 1950K. The maximum TET may occur, for example, at a high thrust condition, for example at a maximum take-off (MTO) condition.

A fan blade and/or aerofoil portion of a fan blade described and/or claimed herein may be manufactured from any suitable material or combination of materials. For example at least a part of the fan blade and/or aerofoil may be manufactured at least in part from a composite, for example a metal matrix composite and/or an organic matrix composite, such as carbon fibre. By way of further example at least a part of the fan blade and/or aerofoil may be manufactured at least in part from a metal, such as a titanium based metal or an aluminium based material (such as an aluminium-lithium alloy) or a steel based material. The fan blade may comprise at least two regions manufactured using different materials. For example, the fan blade may have a protective leading edge, which may be manufactured using a material that is better able to resist impact (for example from birds, ice or other material) than the rest of the blade. Such a leading edge may, for example, be manufactured using titanium or a titanium-based alloy. Thus, purely by way of example, the fan blade may have a carbon-fibre or aluminium based body (such as an aluminium lithium alloy) with a titanium leading edge.

A fan as described and/or claimed herein may comprise a central portion, from which the fan blades may extend, for example in a radial direction. The fan blades may be attached to the central portion in any desired manner. For example, each fan blade may comprise a fixture which may engage a corresponding slot in the hub (or disc). Purely by way of example, such a fixture may be in the form of a dovetail that may slot into and/or engage a corresponding slot in the hub/disc in order to fix the fan blade to the hub/disc. By way of further example, the fan blades maybe formed integrally with a central portion. Such an arrangement may be referred to as a blisk or a bling. Any suitable method may be used to manufacture such a blisk or bling. For example, at least a part of the fan blades may be machined from a block and/or at least part of the fan blades may be attached to the hub/disc by welding, such as linear friction welding.

The gas turbine engines described and/or claimed herein may or may not be provided with a variable area nozzle (VAN). Such a variable area nozzle may allow the exit area of the bypass duct to be varied in use. The general principles of the present disclosure may apply to engines with or without a VAN.

The fan of a gas turbine as described and/or claimed herein may have any desired number of fan blades, for example 14, 16, 18, 20, 22, 24 or 26 fan blades.

As used herein, cruise conditions may mean cruise conditions of an aircraft to which the gas turbine engine is attached. Such cruise conditions may be conventionally defined as the conditions at mid-cruise, for example the conditions experienced by the aircraft and/or engine at the midpoint (in terms of time and/or distance) between top of climb and start of decent.

Purely by way of example, the forward speed at the cruise condition may be any point in the range of from Mach 0.7 to 0.9, for example 0.75 to 0.85, for example 0.76 to 0.84, for example 0.77 to 0.83, for example 0.78 to 0.82, for example 0.79 to 0.81, for example on the order of Mach 0.8, on the order of Mach 0.85 or in the range of from 0.8 to 0.85. Any single speed within these ranges may be the cruise condition. For some aircraft, the cruise conditions may be outside these ranges, for example below Mach 0.7 or above Mach 0.9.

Purely by way of example, the cruise conditions may correspond to standard atmospheric conditions at an altitude that is in the range of from 10000m to 15000m, for example in the range of from 10000m to 12000m, for example in the range of from 10400m to 11600m (around 38000 ft), for example in the range of from 10500m to 11500m, for example in the range of from 10600m to 11400m, for example in the range of from 10700m (around 35000 ft) to 11300m, for example in the range of from 10800m to 11200m, for example in the range of from 10900m to 11100m, for example on the order of 11000m. The cruise conditions may correspond to standard atmospheric conditions at any given altitude in these ranges.

Purely by way of example, the cruise conditions may correspond to: a forward Mach number of 0.8; a pressure of 23000 Pa; and a temperature of -SS degrees C. Purely by way of further example, the cruise conditions may correspond to: a forward Mach number of 0.85; a pressure of 24000 Pa; and a temperature of -54 degrees C (which may be standard atmospheric conditions at 35000 ft).

As used anywhere herein, "cruise" or "cruise conditions" may mean the aerodynamic design point. Such an aerodynamic design point (or ADP) may correspond to the conditions (comprising, for example, one or more of the Mach Number, environmental conditions and thrust requirement) for which the fan is designed to operate. This may mean, for example, the conditions at which the fan (or gas turbine engine) is designed to have optimum efficiency.

In use, a gas turbine engine described and/or claimed herein may operate at the cruise conditions defined elsewhere herein. Such cruise conditions may be determined by the cruise conditions (for example the mid-cruise conditions) of an aircraft to which at least one (for example 2 or 4) gas turbine engine may be mounted in order to provide propulsive thrust.

The skilled person will appreciate that except where mutually exclusive, a feature or parameter described in relation to any one of the above aspects may be applied to any other aspect. Furthermore, except where mutually exclusive, any feature or parameter described herein may be applied to any aspect and/or combined with any other feature or parameter described herein.

Brief Description of the Drawings

Embodiments 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; Figure 2 is a close up sectional side view of an upstream portion of a gas turbine engine; Figure 3 is a partially cut-away view of a gearbox for a gas turbine engine; Figure 4 is an external view of a male-to-female beam seal fluid coupling assembly; Figure 5 is a sectional side view of a beam seal element; Figure 6 is a sectional side view of a male-to-female beam seal fluid coupling assembly before tightening the components together; Figure 7 is a sectional side view of a female-to-female beam seal fluid coupling assembly before tightening the components together; Figure 8 is a sectional side view of a male-to-female beam seal fluid coupling assembly comprising a first fluid restricting component; Figure 9 is a sectional side view of a male-to-female beam seal fluid coupling assembly comprising a second fluid restricting component; and Figure 10 is a sectional side view of a male-to-female beam seal fluid coupling assembly comprising a third fluid restricting component.

Detailed Description

Figure 1 illustrates a gas turbine engine 10 having a principal rotational axis 9. The engine 10 comprises an air intake 12 and a propulsive fan 23 that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 comprises a core 11 that receives the core airflow A. The engine core 11 comprises, in axial flow series, a low pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, a low pressure turbine 19 and a core exhaust nozzle 20. A nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass exhaust nozzle 18. The bypass airflow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low pressure turbine 19 via a shaft 26 and an epicyclic gearbox 30.

In use, the core airflow A is accelerated and compressed by the low pressure compressor 14 and directed into the high pressure compressor 15 where further compression takes place. The compressed air exhausted from the high pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines 17, 19 before being exhausted through the core exhaust nozzle 20 to provide some propulsive thrust. The high pressure turbine 17 drives the high pressure compressor 15 by a suitable interconnecting shaft 27. The fan 23 generally provides the majority of the propulsive thrust. The epicyclic gearbox 30 is a reduction gearbox.

An exemplary arrangement for a geared fan gas turbine engine 10 is shown in Figure 2. The low pressure turbine 19 (see Figure 1) drives the shaft 26, which is coupled to a sun wheel, or sun gear, 28 of the epicyclic gear arrangement 30. Radially outwardly of the sun gear 28 and intermeshing therewith is a plurality of planet gears 32 that are coupled together by a planet carrier 34. The planet carrier 34 constrains the planet gears 32 to precess around the sun gear 28 in synchronicity whilst enabling each planet gear 32 to rotate about its own axis.

The planet carrier 34 is coupled via linkages 36 to the fan 23 in order to drive its rotation about the engine axis 9. Radially outwardly of the planet gears 32 and intermeshing therewith is an annulus or ring gear 38 that is coupled, via linkages 40, to a stationary supporting structure 24.

Note that the terms "low pressure turbine" and "low pressure compressor" as used herein may be taken to mean the lowest pressure turbine stages and lowest pressure compressor stages (i.e. not including the fan 23) respectively and/or the turbine and compressor stages that are connected together by the interconnecting shaft 26 with the lowest rotational speed in the engine (i.e. not including the gearbox output shaft that drives the fan 23). In some literature, the "low pressure turbine" and "low pressure compressor" referred to herein may alternatively be known as the "intermediate pressure turbine" and "intermediate pressure compressor". Where such alternative nomenclature is used, the fan 23 may be referred to as a first, or lowest pressure, compression stage.

The epicyclic gearbox 30 is shown by way of example in greater detail in Figure 3. Each of the sun gear 28, planet gears 32 and ring gear 38 comprise teeth about their periphery to intermesh with the other gears. However, for clarity only exemplary portions of the teeth are illustrated in Figure 3. There are four planet gears 32 illustrated, although it will be apparent to the skilled reader that more or fewer planet gears 32 may be provided within the scope of the claimed invention. Practical applications of a planetary epicyclic gearbox generally comprise at least three planet gears 32.

The epicyclic gearbox 30 illustrated by way of example in Figures 2 and 3 is of the planetary type, in that the planet carrier 34 is coupled to an output shaft via linkages 36, with the ring gear 38 fixed. However, any other suitable type of epicyclic gearbox 30 may be used. By way of further example, the epicyclic gearbox 30 may be a star arrangement, in which the planet carrier 34 is held fixed, with the ring (or annulus) gear 38 allowed to rotate. In such an arrangement the fan 23 is driven by the ring gear 38. By way of further alternative example, the gearbox 30 may be a differential gearbox in which the ring gear 38 and the planet carrier 34 are both allowed to rotate.

It will be appreciated that the arrangement shown in Figures 2 and 3 is by way of example only, and various alternatives are within the scope of the present disclosure. Purely by way of example, any suitable arrangement may be used for locating the gearbox 30 in the engine 10 and/or for connecting the gearbox 30 to the engine 10. By way of further example, the connections (such as the linkages 36, 40 in the Figure 2 example) between the gearbox 30 and other parts of the engine 10 (such as the input shaft 26, the output shaft and the fixed structure 24) may have any desired degree of stiffness or flexibility. By way of further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine (for example between the input and output shafts from the gearbox and the fixed structures, such as the gearbox casing) may be used, and the disclosure is not limited to the exemplary arrangement of Figure 2. For example, where the gearbox 30 has a star arrangement (described above), the skilled person would readily understand that the arrangement of output and support linkages and bearing locations would typically be different to that shown by way of example in Figure 2.

Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of gearbox styles (for example star or planetary), support structures, input and output shaft arrangement, and bearing locations.

Optionally, the gearbox may drive additional and/or alternative components (e.g. the intermediate pressure compressor and/or a booster compressor).

Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown in Figure 1 has a split flow nozzle 18, meaning that the flow through the bypass duct 22 has its own nozzle 18 that is separate to and radially outside the core exhaust nozzle 20. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct 22 and the flow through the core 11 are mixed, or combined, before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the disclosure may apply, for example, to any type of gas turbine engine, such as an open rotor (in which the fan stage is not surrounded by a nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine 10 may not comprise a gearbox 30.

The geometry of the gas turbine engine 10, and components thereof, is defined by a conventional axis system, comprising an axial direction (which is aligned with the rotational axis 9), a radial direction (in the bottom-to-top direction in Figure 1), and a circumferential direction (perpendicular to the page in the Figure 1 view). The axial, radial and circumferential directions are mutually perpendicular.

Figure 4 illustrates a first embodiment of a beam seal fluid coupling assembly 100. The beam seal fluid coupling assembly 100 comprises a first fluid conduit 101 and a second fluid conduit 102. The first fluid conduit 101 and the second fluid conduit 102 are coupled together by a first fluid conduit coupling component 103 and a second fluid conduit coupling component 104 which is connected to the second fluid conduit 102. The first fluid conduit coupling component 103 comprises a first flange surface 130. The second fluid conduit coupling component 104 comprises a rigidly fixed flange 105 having a second flange surface 131. The first and second flange surfaces 130,131, which extend radially, engage each other.

Figure 5 illustrates a sectional side view of a beam seal element 110. The beam seal element 110 is connected to the first fluid conduit 101 in a fluid-tight manner. The beam seal element 110 is held captive between the first fluid conduit coupling component 103 and the second fluid conduit coupling component 104. The beam seal element 110 forms a male part of the assembly and fits inside the second fluid conduit coupling component 104, which forms a female part of the assembly. In particular, the beam seal element 110 is held between a first mating surface 120 of the first fluid conduit coupling component 103 and a second mating surface 121 of the second fluid conduit coupling component 104. The first mating surface 120 may be contiguous with the first flange surface 130. By contrast, the second mating surface 121 may be axially set back from the second flange surface 131.

The beam seal element 110 comprises a lip seal 111 at a distal end, an elongate section 112, and an abutment surface 113 at the end opposite the lip seal, nearest the first fluid conduit 101. As shown in Figure 5, the elongate section 112 has a convoluted profile. The convoluted profile may comprise at least one convolution, where the or each convolution comprises a diagonal section (e.g. angled with respect to the radial direction and/or axial direction) and an adjacent straight section (e.g substantially extending in the axial direction). The convoluted profile is able to absorb a proportion of any excess force exerted, for example axially, on the lip seal 111, such that the elongate section 112 deforms elastically in preference to the lip seal deforming either plastically or excessively elastically. This allows an effective seal to be maintained even when excessive forces are exerted upon the lip seal 111. Upon removal of the excess force upon the lip seal 111, the lip seal 111 and elongate section 112 are able to recover to their shape before the application of the force. In this way, the lip seal 111 maintains its shape and angle so that it is able to repeatedly form an effective seal after cycles of loading, unloading; pressurisation, depressurisation; disconnection, reconnection. Accordingly, the beam seal element 110, by virtue of the elongate section 112, is resiliently compressible.

Figure 6 illustrates the beam seal fluid coupling assembly 100 and shows the beam seal element 110 having been inserted into the second fluid conduit coupling component 104.

The first fluid conduit 101 and the second fluid conduit 102 are aligned such that the flange surfaces 130, 131, the first fluid conduit coupling component 103 and the second fluid conduit coupling component 104 are substantially parallel. The first fluid conduit coupling component 103 comprises one or more openings 106, 107, 108, 109, which are configured to receive fasteners (not shown), such as bolts or studs, to fasten the first fluid conduit coupling component 103 to the second fluid conduit coupling component 104. In the embodiment depicted, openings are provided, although other numbers of openings are contemplated. The openings 106-109 may be distributed, for example equiangularly, about a perimeter of the first fluid conduit coupling component 103. The second fluid conduit coupling component 104 may be provided with corresponding openings (not shown) that align with the openings 106-109 of the first fluid conduit coupling component 103. It is noted that the exact angle of the lip seal 111 prior to insertion is similar to the angle of the second mating surface 121, but not necessarily identical. Bolts or studs inserted into the openings 106-109 produce a clamping force between the first fluid conduit coupling component 103 and the flange 105 of the second fluid conduit coupling component 104.

This clamping force causes the first mating surface 120 of the first fluid conduit coupling component 103 to engage the abutment surface 113 of the beam seal element 110, which in turn causes the lip seal 111 of the beam seal element 110 to deform and engage the second mating surface 121. At the interface between the lip seal 111 and the second mating surface 121, a fluid-tight seal is formed.

Figure 7 illustrates a second embodiment, the female-to-female beam seal fluid coupling assembly 200, in an assembled state. The features common to both the female-to-female embodiment 200 and the male-to-female embodiment 100 have the same numbering across Figures 4, 5, 6 and 7. It is noted that features with the same numbering and/or naming also exhibit the same functionalities.

The second embodiment is substantially identical to the first embodiment except for the following features which will be discussed in detail.

In the second embodiment, the first fluid conduit coupling component 103 of the first embodiment 100 has been replaced by a first fluid conduit coupling component 203 (e.g. a female part), mirroring the second fluid conduit coupling component 104 of the first embodiment, which is also present in the second embodiment. As such, the features of the first fluid conduit coupling component 203 substantially mirror those of the second fluid conduit coupling component 104. The first fluid conduit coupling component 203 therefore comprises a flange 203a, a first mating surface 220, and a first flange surface 230. The flange 203a may comprise one or more openings 106, 107, 108, 109 configured to receive fasteners for engaging corresponding openings in the flange 105. Also, in contrast with the first embodiment, the first fluid conduit coupling component 203 connects to the first fluid conduit 101. The two fluid conduits 101, 102 to be joined therefore both have the same end attachments 203, 104 respectively.

The second embodiment comprises a beam seal element 210 which is not coupled to the first fluid conduit and as such is a removable component. The beam seal element 210 comprises an elongate section 212 provided between a first lip seal 213 and a second lip seal 111. The elongate section 212 comprises a plurality of convolutions. The elongate section 212, and thus the beam seal element 210, is designed to have compressibility characteristics similar to those of as the elongate section 112 and the beam seal element 110. The beam seal element 210 and the lip seals 213, 111 behave in a similar manner to the beam seal element 110 and the lip seal 111 of the first embodiment 100 during compression, tightening, loading and seal formation.

It is noted that in the second embodiment 200, the abutment surface 113 of the first embodiment 100 has effectively been provided by the first lip seal 213, which has a surface that abuts the first mating surface 220. The first mating surface 220 of the second embodiment 200 is capable of forming a fluid-tight seal with the first lip seal 213, which may contrast with the first mating surface 120 of the first embodiment 100, which abuts the abutment surface 113 without necessarily forming a fluid-tight seal.

In either of the first and second embodiments, a higher clamping force increases the compressive force between the lip seal 111 and the second mating surface 121. In the case of Figure 6, where there is a small interface between the lip seal 111 and the second mating surface 121, as the components are brought together, a higher compressive force causes the lip seal 111 to deflect, such that the angle of the lip seal 111 approaches the angle of the second mating surface 121. In doing so, the interface at which the lip seal 111 and the second mating surface 121 meet increases in area, creating a larger sealing interface. At a certain compressive force, the whole surface of the lip seal 111 is in contact with the second mating surface 121. The same effect occurs in the second embodiment with both the first and second lip seals 213, 111 being compressed against their respective mating surfaces 220, 121.

Each elongate section 112, 212 provides additional capacity to compensate for externally driven changes in the compressive force on the lip seals 111, 213 whilst still maintaining a fluid-tight seal. Externally driven changes include expansion or contraction, such as thermal expansion or contraction; component deflection; vibration; whole system deflections; bolt overtightening; bolt under-tightening and manufacturing tolerance variation. For example, in circumstances when the clamping force is greater than optimum, the convolutions absorb at least some of the additional compressive force whilst still maintaining a fluid-tight seal at the lip seals 111, 213. In circumstances when the clamping force is less than optimum, the elongate sections 112, 212 provide a secondary positive reinforcement by providing additional compression on the fluid-tight seal.

It is noted that the first fluid conduit coupling components 103, 203 and the second fluid conduit coupling component 104 are arranged such that full tightening of the securing bolts is not necessary for the lip seals 111, 213 to engage the mating surfaces 121, 220, or for the first mating surface 120 to engage the abutment surface 113, such that an effective seal is created. Similarly, overtightening of the securing bolts does not have a detrimental effect on the fluid-tight seal as a result of the aforementioned additional end load capacity provided by the elongate sections 112, 212. In this way, the elongate sections 112, 212 allow a range of bolt torque values for which an effective seal is created in the fluid coupling assemblies of

the present disclosure.

The beam seal fluid coupling assemblies 100, 200 allows standard bolts, for example of one single size, to be used for beam seal fluid coupling assemblies of different dimensions, such that standard tooling is required, and there is greater consistency of assembly processes. One example of this is that on one single platform, for example a gas turbine engine, where many different beam seal fluid coupling assemblies of different dimensions are used, only one size of bolt is required, and consequently only one torque value for all of the bolts used in fluid coupling assemblies is required across the whole platform. This greatly simplifies assembly procedures and reduces the risk of incorrect assembly along with its undesirable consequences. Additionally, the beam seal fluid coupling assemblies 100, 200 can be used to couple fluid conduits of different diameters or dimensions.

In the above-described embodiments, the fluid-tight seal is formed without the necessity of additional components. These additional components are often made from materials which degrade more quickly than the primary materials of coupling assemblies, or degrade in conditions that the primary materials can withstand. This has the advantage that the coupling assembly maintains its seal over a greater lifespan or during more extreme conditions, for example during fire conditions which additional components may struggle to withstand. In addition, excess components used for fire protection, such as loose parts or fire sleeves, would become unnecessary. These factors simplify the assembly further.

In other embodiments, a removable component may be fitted to either of the first and second embodiments, for example between one or both of the lip seals 213, 111 and their respective mating surfaces 220, 111, to create a flow restriction. This component may have an orifice within it to optimise the fluid flow through the coupling assembly.

An example of one such embodiment is shown in Figure 8, where a first fluid restricting component 308 has been inserted between the first fluid conduit coupling component 103 and the second fluid conduit coupling component 104. The first fluid restricting component 308 extends in a direction having a radial component towards the centre of the common axis of the first and second fluid conduits 101, 102, and may also extend in an axial direction into the second fluid conduit 102. The first fluid restricting component may have a thickness greater than that of the first or second fluid conduits 101, 102.

Figure 9 shows another such embodiment, in this case with a second fluid restricting component 309. The second fluid restricting component 309 is again insertable between the first and second fluid conduits 101, 102.The second fluid restricting component 309 extends in a direction having a radial component towards the centre of the common axis of the first and second fluid conduits 101, 102, and may also extend in an axial direction into the second fluid conduit 102 to a greater extent than the first fluid restricting component. The second fluid restricting component may have a thickness that is similar (e.g. substantially equal to) the thickness of the first or second fluid conduits 101, 102.

Figure 10 shows another such embodiment, in which a third fluid restricting component 310 has been inserted between the lip seal 111 and the second mating surface 121. The third fluid restricting component 310 extends with a minimal axial component and extends radially inwards towards the common central axis of the first and second fluid conduits 101, 102. The third fluid restricting component may engage the second fluid conduit coupling component 104 with an interference fit.

At the centremost part of the first, second and third fluid restricting components 308, 309, 310, there is an opening 308a, 309a, 310a of dimensions smaller than those of either the first or second fluid conduits 101, 102, such that the flow of fluid through the beam seal fluid coupling assemblies into which the fluid restricting components 308, 309, 310 are inserted may be restricted.

It is noted that in each of the embodiments shown in Figures 8, 9, 10, a fluid tight seal is formed between the lip seal 111, 213 and the removable component 308, 309, 310, rather than between the lip seal 111, 213 and either the first or second mating surface 121, 220. A fluid-tight seal may also be formed between the removable component 308, 309, 310 and the mating surface 121, 220 which it abuts.

Additionally, it is noted that although the first fluid restricting component 308, second fluid restricting component 309 and third fluid restricting component 310 are shown in the first embodiment 100 in Figures 8, 9, 10, they may also be insertable within the second embodiment 200 in a similar manner.

Alternatively, removable components may exist not comprising an orifice at all. In this case, the fluid coupling assembly would be acting like a blanking cap to seal off the end of a fluid conduit in either a temporary or permanent arrangement.

The profile of the elongate section 112, 212 is designed such that the amplitude of convolution (e.g. in the radial direction) is greater than the thickness of the wall of the fluid conduit. The profile is variable such that the compression characteristics of the beam seal element can be better suited to the environment and conditions in which the beam seal fluid coupling assembly is used. Variable factors in the profile of the convolutions include the wall thickness, the number of convolutions, their shape, pitch, height and length.

The beam seal fluid coupling assemblies of the present disclosure may be manufactured from materials including stainless steel, titanium alloys, Inconel or any other suitable material or alloy. Fluid conduits being coupled by the beam seal fluid coupling assemblies may carry fluids including hydraulic fluids, fuel, air, oil or any other fluid. The fluid within the beam seal fluid coupling assembly may be at pressures in excess of 8000 psi.

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 sub-combinations of one or more features described herein.

Claims

CLAIMS1. A beam seal fluid coupling assembly (100, 200) for a gas turbine engine (10) comprising: a beam seal element (110, 210); a first fluid conduit coupling component (103, 203); and a second fluid conduit coupling component (104), the first fluid conduit coupling component (103, 203) and the second fluid conduit coupling component (104) being connectable to one another; wherein the beam seal element (110, 210) comprises: an elongate section (112, 212) defined by a circumferentially and longitudinally extending wall having a convoluted profile along the length of the elongate section (112, 212) such that the elongate section (112, 212) is compressible; a lip seal (111) provided at a distal end of the beam seal element (110, 210), the lip seal (111) extending from the wall in a direction with a radial component; and an abutment surface (113, 213) provided at an end of the elongate section (112, 212) opposite the lip seal (111), wherein the beam seal element (110, 210) is providable between a respective first mating surface (120, 220) and a second mating surface (121) of the first fluid conduit coupling component (103, 203) and the second fluid conduit coupling component (104), such that the first mating surface (120, 220) engages the abutment surface (113, 213) of the beam seal element (110, 210) and the second mating surface (121) engages the lip seal (111).
2. The beam seal fluid coupling assembly (100, 200) according to claim 1, wherein each of the first fluid conduit coupling component (103, 203) and the econd fluid conduit coupling component (104) comprises a flange (105, 203a) which extends radially.
3. The beam seal fluid coupling assembly (100, 200) according to claim 2 wherein the first fluid conduit coupling component (103, 203) and the second fluid conduit coupling component (104) are joined by virtue of at least one bolt passing through the flanges (105, 203a) of the first fluid conduit coupling component (103, 203) and the second fluid conduit coupling component (104).
4. The beam seal fluid coupling assembly (100, 200) according to any preceding claim, wherein the beam seal fluid coupling assembly (100, 200) further comprises a fluid-restricting component insertable within the beam seal fluid coupling assembly (100, 200) in order to restrict the fluid flow through the beam seal fluid coupling assembly (100, 200). 5. 6. 7. 8. 9. 10. 11.
The beam seal fluid coupling assembly (100, 200) according to claim 4, wherein the fluid-restricting component comprises an opening to permit flow therethrough.
The beam seal fluid coupling assembly (100, 200) according to claim 4, wherein the fluid-restricting component prevents fluid flow through the beam seal fluid coupling assembly (100, 200).
The beam seal fluid coupling assembly (100, 200) according to any one f claims 4 to 6, wherein the fluid-restricting component is providable between the lip seal (111) of the beam seal element (110, 210) and the mating surface (121) of the second fluid conduit coupling component (104).
The beam seal fluid coupling assembly (100, 200) according to any preceding claim, wherein the second fluid conduit coupling component (104) is connectable to a second fluid conduit (102).
The beam seal fluid coupling assembly (100, 200) according to any preceding claim, wherein the beam seal element (110, 210) is connectable to a first fluid conduit (101).
The beam seal fluid coupling assembly (100, 200) according to any one of claims 1 to 8, wherein the first fluid conduit coupling component (103) is connectable to a first fluid conduit (101).
The beam seal fluid coupling assembly (100, 200) according to claim 10, wherein the abutment surface (113, 213) of the beam seal element (110, 210) is a further lip seal (213) extending from the wall in a direction with a radial component.
12. The beam seal fluid coupling assembly (100, 200) according to any preceding claim, wherein the convoluted profile comprises at least one convolution, the or each convolution comprising a diagonal section and an adjacent straight section.
13. A gas turbine engine (10) for an aircraft, wherein the gas turbine engine comprises: an engine core (11) comprising a turbine (19), a compressor (14), and a core shaft (26) connecting the turbine to the compressor; a fan (23) located upstream of the engine core, the fan comprising a plurality of fan blades; and the beam seal fluid coupling assembly (100, 200) according to any preceding claim.
14. The gas turbine engine (10) according to claim 13, wherein the gas turbine engine further comprises: a gearbox (30) that receives an input from the core shaft (26) and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft; and the beam seal fluid coupling assembly (100, 200) according to any preceding claim.
15. The gas turbine engine according to claim 13 or 14, wherein: the turbine is a first turbine (19), the compressor is a first compressor (14), and the core shaft is a first core shaft (26); the engine core further comprises a second turbine (17), a second compressor (15), and a second core shaft (27) connecting the second turbine to the second compressor; and the second turbine, second compressor, and second core shaft are arranged to rotate at a higher rotational speed than the first core shaft.