GB2587632A

GB2587632A - A pulsation dampener and a method of manufacturing a pulsation dampener

Info

Publication number: GB2587632A
Application number: GB1914189.4A
Authority: GB
Inventors: Gupta Alok
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2019-10-02
Filing date: 2019-10-02
Publication date: 2021-04-07
Also published as: GB201914189D0

Abstract

A pulsation dampener 218, for a fluid conduit (Fig 4, 206) the pulsation dampener 218 comprising a receptacle 220, a neck 222, a first tube 224 and a second tube 226, wherein a downstream end of the first tube 224 is fluidically connected to an upstream end of the second tube 226, wherein a first end of the neck 222, is fluidically connected to the downstream end of the first tube 224 and the upstream end of the second tube 226, wherein a second end of the neck 222 is fluidically connected to the receptacle 220, wherein the first tube 224, the second tube 226, the neck 222 and the receptacle 220 are formed as a single unitary component (e.g. by an additive manufacturing process). Embodiments include: a gas turbine engine for an aircraft comprising a pulsation dampener; and method of manufacturing a pulsation dampener.

Description

A PULSATION DAMPENER AND A METHOD OF MANUFACTURING A PULSATION DAMPENER

Field of the disclosure

The present disclosure relates to a pulsation dampener and a method of manufacturing a pulsation dampener.

Background

Pulsation dampeners are a type of hydraulic damper used in aircraft fuel systems to damp pressure fluctuations in hydraulic pipes caused by the operation of pumps. In known aircraft fuel systems, pulsation dampeners comprise an acoustic cavity in the form of a receptacle, a short tube in the form of a neck and a T-fitting. The acoustic cavity is formed by two hemispheres that have been machined and then welded together. A first and second opening of the T-fitting are welded to an inlet and outlet pipe, respectively. The short tube is welded to the acoustic cavity and to a third opening of the T-fitting such that fluid communication is established between the acoustic cavity, the short tube, the T-fitting and the inlet and outlet pipes. Such pulsation dampeners act as Helmholtz resonators. In particular, the fluid in the short tube acts as a vibrating mass and the fluid in the acoustic cavity acts as a spring. By matching the natural frequency of the pulsation dampener to a critical frequency of the pressure fluctuations in the inlet and outlet pipes, the pulsation dampener can reduce the vibrations in the pipe caused by the pressure fluctuations.

Stresses develop in pulsation dampeners during operation. The walls of the components and the welds between them are made sufficiently thick to mitigate the effects of stress concentrations and prevent component failure. However, this increases the weight of the pulsation dampener, and, thus, reduces the efficiency of the aircraft in which the pulsation dampener is installed.

It is therefore desirable to provide an improved pulsation dampener and method of manufacturing a pulsation dampener.

Summary of the disclosure

According to a first aspect there is provided a pulsation dampener for a fluid conduit, the pulsation dampener comprising a receptacle, a neck, a first tube and a second tube, wherein a downstream end of the first tube is fluidically connected to an upstream end of the second tube, wherein a first end of the neck is fluidically connected to the downstream end of the first tube and the upstream end of the second tube, wherein a second end of the neck is fluidically connected to the receptacle, wherein the first tube, the second tube, the neck and the receptacle are formed as a single unitary component by an additive manufacturing process.

An upstream end of the first tube may comprise a first radially extending flange for connection to an upstream tube of the fluid conduit. The downstream end of the second tube may comprise a second radially extending flange for connection to a downstream tube of the fluid conduit. The first radially extending flange and the second radially extending flange may be formed as part of the single unitary component by the additive manufacturing process.

An upstream end of the first tube may comprise a first sleeve portion for receiving an upstream tube of the fluid conduit. A downstream end of the second tube may comprise a second sleeve portion for receiving a downstream tube of the fluid conduit. The first sleeve portion and the second sleeve portion may be formed as part of the single unitary component by the additive manufacturing process.

An upstream end of the first tube may be welded to an upstream tube of the fluid conduit so as to form a first butt joint. A downstream end of the second tube may be welded to a downstream tube of the fluid conduit so as to form a second butt joint.

The neck may be connected to the receptacle by a fillet. The neck may be connected to the first and second tubes by a fillet. The fillets may be formed as part of the single unitary component by the additive manufacturing process.

Each fillet may have a radius of curvature of between 0.5 and 10 millimetres.

The thickness of a wall defining the neck and/or the first tube and/or the second tube may be greater than the thickness of a wall defining the receptacle.

The longitudinal axis of the first tube may be angled with respect to the longitudinal axis of the second tube.

None of the longitudinal axis of the first tube, the longitudinal axis of the second tube and the longitudinal axis of the neck may be coplanar.

The longitudinal axis of the first tube may be parallel to the longitudinal axis of the second tube.

The longitudinal axis of the first tube and the longitudinal axis of the second tube may be coaxial.

The first tube and the second tube may have a circular cross-sectional profile. The diameter of the first tube may be greater than or less than the diameter of the second tube.

At least a portion of the first tube and/or the second tube may corrugated so as to increase its flexibility.

The receptacle may be spherical or cylindrical.

The pulsation dampener may further comprise a particle damper coupled to the receptacle. The particle damper may comprise a cavity containing powder.

The cavity of the particle damper may be defined by an annular wall that extends around the receptacle. The annular wall may be formed as part of the single unitary component by the additive manufacturing process.

According to a second aspect there is provided a gas turbine engine for an aircraft, the gas turbine engine comprising: an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan comprising a plurality of fan blades; a 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; and a pulsation dampener as described in any preceding statement.

According to a third aspect there is provided a method of manufacturing a pulsation dampener as described in any preceding statement, the method comprising the steps of: providing a powder bed comprising a first portion of powder and a second portion of powder; and solidifying the first portion of powder so as to form a single unitary solid body, the single unitary solid body comprising the receptacle, the neck, the first tube and the second tube.

According to a fourth aspect there is provided a method of manufacturing a pulsation dampener as described in any preceding statement, the method comprising the steps of: ejecting a portion of powder; solidifying the portion of powder so as to form a single unitary solid body, the single unitary solid body comprising the receptacle, the neck, the first tube and the second tube.

According to a fifth aspect there is provided method of manufacturing a pulsation dampener as described in any preceding statement, the method comprising the steps of: providing a powder bed comprising a first portion of powder; solidifying the first portion of powder so as to form part of a single unitary solid body, the part of the single unitary solid body defining an open cavity having one or more openings into the open cavity; ejecting a second portion of powder into the open cavity via the one or more openings so as to at least partially fill the open cavity with the second portion of powder; ejecting a third portion of powder; and solidifying the third portion of powder so as to occlude the one or more openings of the open cavity and form the single unitary body, the single unitary body having an enclosed cavity in which the second portion of powder is located, wherein the second portion of powder is not solidified, and wherein the single unitary solid body comprises the receptacle, the neck, the first tube and the second tube.

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 a 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 25 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, 01 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), 350 cm, 360 cm (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 U. 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/U2, where dH is the enthalpy rise (for example the 1-D average enthalpy rise) across the fan and Ufip 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-ls, 105 Nkals, 100 Nkg-ls, 95 Nkals, 90 Nkes, 85 Nkals or 80 Nkg-ls. 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-ls to 100 Nkg-ls, or 85 Nkes to 95 Nkals. 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 bladed disc or a bladed ring. Any suitable method may be used to manufacture such a bladed disc or bladed ring. 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 -55 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 a schematic view of a hydraulic system for an aircraft fuel system; Figure 5 is a close-up view of a pulsation dampener of the aircraft fuel system; Figure 6 is a cross-sectional view of the pulsation dampener; Figure 7 is a close-up view of a first alternative pulsation dampener; Figure 8 is a close-up view of a second alternative pulsation dampener; Figure 9 is a close-up view of a third alternative pulsation dampener; Figure 10 is a cross-sectional view of a fourth alternative pulsation dampener; Figure 11 is a cross-sectional view of a fifth alternative pulsation dampener; Figure 12 is a first cross-sectional schematic view of an apparatus for carrying out a first additive manufacturing process; Figure 13 is a flowchart of the first additive manufacturing process; Figure 14 is a second cross-sectional schematic view of the apparatus for carrying out the first additive manufacturing process; Figure 15 is a first cross-sectional schematic view of an apparatus for carrying out a second additive manufacturing process; Figure 16 is a flowchart of the second additive manufacturing process; Figure 17 is a second cross-sectional schematic view of the apparatus for carrying out the second additive manufacturing process; and Figure 18 is a flowchart of a third additive manufacturing process.

Detailed description

Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art.

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 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 30 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, 20 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 shows a hydraulic system 200 for an aircraft fuel system. The hydraulic system 200 comprises a pump 202 and a device 204 connected by an outward fluid conduit 206 and a return fluid conduit 208. The outward and return fluid conduits 206, 208 are each connected to a first support 210 and a second support 212. The outward fluid conduit 206 comprises an upstream tube 214 and a downstream tube 216. The upstream and downstream tubes 214, 216 are connected to a pulsation dampener 218.

The pulsation dampener 218 is supported by a bracket 219.

Figure 5 is a close-up view of the pulsation dampener 218. The pulsation dampener 218 comprises a receptacle 220 (i.e. a vessel, container or chamber), a tubular neck 222, a first tube 224 and a second tube 226. The first and second tubes 226 and the neck 222 have a circular cross-sectional profile. The receptacle 220 is spherical. A first end of the receptacle 220 is connected to a first end of the neck 222. A second end of the receptacle 220 is connected to the bracket 219. The connection between the neck 222 and the receptacle 220 is formed by a fillet 242. The longitudinal axis 228 of the neck 222 is aligned with the centre of the receptacle 220. A second end of the neck 222 is connected to the first tube 224 and the second tube 226 at an interface between the first and second tubes 224, 226. The first tube 224 and the second tube 226 have the same diameter. The longitudinal axis 230 of the first tube 224 is aligned with the longitudinal axis 232 of the second tube 226. The longitudinal axis 230 of the first tube 224 and the longitudinal axis 232 of the second tube 226 extend through a common point and are coaxial. The longitudinal axes 230, 232 of the first and second tubes 224, 226 are perpendicular to the longitudinal axis 228 of the neck 222. The connection between the neck 222 and the first and second tubes 224, 226 is formed by a fillet 244. An upstream end of the first tube 224 is welded to a downstream end of the upstream tube 214. A downstream end of the second tube 226 is welded to an upstream end of the downstream tube 216. The welding process may be a laser welding process and results in the formation of beads 271. The connection between the first tube 224 and the upstream tube 214 and the connection between the second tube 226 and the downstream tube 216 are butt joints. The neck 222 and the first and second tubes 224, 226 form a T-fitting.

Figure 6 is a cross-sectional view of the pulsation dampener 218. As shown, the upstream and downstream tubes 214, 216, the receptacle 220, the neck 222 and the first and second tubes 224, 226 are hollow. The thicknesses of the walls forming the receptacle 220, the neck 222 and the first and second tubes 224, 226 are constant.

Fluid communication is established between the upstream tube 214 and the first tube 224, between the first and second tubes 214, 216 and the neck 222, between the neck 222 and the receptacle 220 and between the second tube 226 and the downstream tube 216.

With reference to Figures 4 and 6, during use, the pump 202 pumps fluid (e.g. hydraulic fluid) along the outward fluid conduit 206 to the device 204. The fluid returns to the pump 202 from the device 204 via the return conduit 208. As the fluid passes along the outward conduit 206, it passes from the upstream tube 214, into the first tube 216, into the second tube 226 and into the downstream tube 216. The interior of the receptacle 220 and the neck 222 are also filled with the fluid. The fluid in the neck 222 acts as a vibrating mass and the fluid in the receptacle 220 acts as a spring. The fluid in the neck 222 and the fluid in the receptacle 220 act to dampen fluctuations in pressure in the fluid passing along the downstream tube 216 of the outward conduit 206 using the principle of a Helmholtz resonator. The geometry of the pulsation dampener 218 determines the frequency that it is able to damp (i.e. its natural frequency). The natural frequency f of the pulsation dampener 218 is determined using the following formula:

A

f 27 (V)(Lc) where c is the velocity of sound in the fluid, A is the cross-sectional area of the interior of the neck 222 on a plane perpendicular to its axis 228, V is the volume of the interior of the receptacle 220 and Lc is the length of the neck 222 with the addition of a correction length. The correction length is added in order to account for the fact that some fluid on either side of the neck 222 also acts as a vibrating mass.

The pulsation dampener 218 is a single, unitary part. It is known to manufacture pulsation dampeners from multiple individual parts that are subsequently welded together. However, forming the pulsation dampener as a unitary part provides a number of advantages over existing arrangements. For example, welds are potential areas of high stress and failure (i.e. stress concentration features), and by eliminating welds the strength and robustness of the component is improved. In known arrangements, high stresses are present in the neck 222 in particular, and reducing likelihood of the neck 222 failing reduces the likelihood of the fluid within the pulsation dampener 218 leaking, which could result in the hydraulic system 200 being deprived of the fluid it needs to operate and result in a fire hazard. Further, reducing the number of parts reduces manufacturing complexity and time (e.g. by reducing the number of manufacturing steps required), reduces cost, reduces weight (thus improving specific fuel consumption) and reduces the likelihood of the manufacturing process going wrong (thus reducing scrap rate).

The pulsation dampener 218 is formed by additive manufacturing. This allows the geometry of the pulsation dampener 218 to be optimised in a number of respects. For example, the pulsation dampener 218 can be manufactured such that the cross-sectional area A of the interior of its neck 222, the volume V of the interior of its receptacle 220 and the length Lc of its neck 222 results in the natural frequency f of the pulsation dampener 218 corresponding to the frequency of the changes in pressure within the outward conduit 206, in accordance with the formula presented above. The shape of the receptacle 220 and the neck 222 can be optimised to improve damping of pressure ripples. Additive manufacturing techniques can produce pulsation dampeners 218 to high accuracy, thereby ensuring that the damping properties of the pulsation dampener 218 are correctly optimised.

The stresses in the pulsation dampener 218 can also be reduced as a result of the additive manufacturing process. For example, the additive manufacturing process allows the pulsation dampener 218 to be formed with fillets 242, 244 that reduce the stresses between the receptacle 220 and the neck 222, thus reducing the likelihood of failure between the receptacle 220 and the neck 222. Likewise, the fillet 244 reduces the stresses between the neck 222 and the first and second tubes 224, 226, thus reducing the likelihood of failure between the neck 222 and the first and second tubes 224, 226. The radius of the fillets 242, 244 may be between 0.5 and 10 millimetres.

Figure 7 is a cross-sectional view of a first alternative pulsation dampener 318. The reference numerals used to denote the features of the first alternative pulsation dampener 318 correspond to those used to denote corresponding features of the pulsation dampener 218, with the addition of a value of 100.

The first alternative pulsation dampener 318 corresponds to the pulsation dampener 218 in most respects. However, the longitudinal axis 332 of the second tube 326 is angled with respect to the longitudinal axis 330 of the first tube 324 (i.e. it is not aligned with the longitudinal axis 330 of the first tube 324). In the arrangement shown in Figure 7, an angle of approximately 135 degrees is formed between the longitudinal axis 330 of the first tube 324 and the longitudinal axis 332 of the second tube 326. However, this angle may differ. In the arrangement shown in Figure 7, the longitudinal axis 330 of the first tube 324 is perpendicular to the longitudinal axis 328 of the neck 322. However, it may be angled at a non-perpendicular angle to the longitudinal axis 328 of the neck 322. In the arrangement shown in Figure 7, the longitudinal axes 328, 330, 332 of the neck 322 and the first and second tubes 324, 326 lie on a single plane (i.e. they are coplanar). However, in alternative arrangements only two of the longitudinal axes are coplanar and the remaining longitudinal axis is angled from the plane on which the two other longitudinal coplanar axes lie. In yet further alternative arrangements, none of the longitudinal axes are coplanar and each are on different planes.

In addition, an upstream end of the first tube 324 is provided with a first radially extending flange 334 and a downstream end of the second tube 326 is provided with a second radially extending flange 336. The upstream tube 214 is provided with a flange 238 that is connected to the first flange 334 and the downstream tube 216 is provided with a flange 240 that is connected to the second flange 336. The neck 322, the first and second tubes 324, 326 and the first and second flanges 334, 336 form the T-fitting. Although not shown, the connection between the first tube 324 and the first radially extending flange 234 may be formed by a fillet, and the connection between the second tube 326 and the second radially extending flange 336 may be formed by a fillet.

Figure 8 is a cross-sectional view of a second alternative pulsation dampener 418.

The reference numerals used to denote the features of the second alternative pulsation dampener 418 correspond to those used to denote corresponding features of the pulsation dampener 218, with the addition of a value of 200.

The second alternative pulsation dampener 418 corresponds to the pulsation dampener 218 in most respects. However, the second tube 426 has a smaller diameter than the first tube 424. In alternative arrangements, the second tube 426 may have a larger diameter than the first tube 424. The second alternative pulsation dampener 418 can thus be used to connect upstream tubes 214 and downstream tubes 216 having different diameters and/or thicknesses. Further, the longitudinal axis 430 of the first tube 424 and the longitudinal axis 432 of the second tube 426 are parallel rather than aligned. The second alternative pulsation dampener 418 can thus be used to connect upstream tubes 214 and downstream tubes 216 that are parallel. In alternative arrangements the first and second tubes 424, 426 have different diameters but are coaxial (i.e. they are aligned).

Figure 9 is a cross-sectional view of a third alternative pulsation dampener 518. The reference numerals used to denote the features of the third alternative pulsation dampener 518 correspond to those used to denote corresponding features of the pulsation dampener 218, with the addition of a value of 300.

The third alternative pulsation dampener 518 corresponds to the pulsation dampener 218 in most respects. However, the first tube 524 comprises an upstream portion 560, a downstream portion 562 and a corrugated portion 564. The upstream portion 560 is connected to the downstream portion 562 by the corrugated portion 564. Likewise, the second tube 526 comprises an upstream portion 566, a downstream portion 568 and a corrugated portion 570. The upstream portion 566 is connected to the downstream portion 568 by the corrugated portion 570. The corrugated portions 564, 570 are relatively flexible and reduce stresses in the upstream and downstream tubes 214, 216.

Figure 10 is a cross-sectional view of a fourth alternative pulsation dampener 618. The reference numerals used to denote the features of the fourth alternative pulsation dampener 618 correspond to those used to denote corresponding features of the pulsation dampener 218, with the addition of a value of 400.

The fourth alternative pulsation dampener 618 corresponds to the pulsation dampener 218 in most respects. However, the receptacle 620 is cylindrical rather than spherical. A proximal wall 650 of the receptacle 620 at a first end of the receptacle 620 is connected to a first end of the neck 622. A distal wall 652 of the receptacle 620 at a second end of the receptacle 620 is connected to a bracket 619. The proximal and distal walls 650, 652 are planar. A cylindrical sidewall 654 extends between the proximal and distal walls 650, 652. The longitudinal axis of the cylindrical receptacle 620 is aligned with the longitudinal axis 628 of the neck 622. A first edge 656 between the proximal wall 650 and the sidewall 654 and a second edge 658 between the distal wall 652 and the sidewall 654 are rounded. The radius of the rounded first and second edges 656, 658 may be between 0.5 and 10 millimetres. In alternative arrangements, the receptacle 620 may have any shape or size that meets the requirements for a particular engine or engine location The wall thickness of the fourth alternative pulsation dampener 618 is variable. This allows the thickness of the walls to be optimised to be sufficiently thick to meet strength requirements, but not too thick such that they are unnecessarily heavy. This minimises the likelihood of failure whilst reducing specific fuel consumption (SFC). In the fourth alternative pulsation dampener 618, the thickness of the walls forming the neck 622 is greater than the thickness of the walls forming the receptacle 620, the first tube 624 and the second tube 626. This increases the strength of the neck 622, which tends to experience relatively high stresses, without unnecessarily increasing the weight of the remaining parts of the fourth alternative pulsation dampener 618. In alternative arrangements, the thickness of the walls forming the neck 622, the first tube 624 and the second tube 626 may be greater than the thickness of the walls forming the receptacle 620.

In addition, the first and second tubes 624, 626 are not provided with first and second flanges. Instead, the first tube 624 comprises a proximal first tube portion 660 and a distal second tube portion 662 forming a sleeve and having a larger internal diameter than the first tube portion 660. Likewise, the second tube 626 comprises a proximal first tube portion 661 and a distal second tube portion 663 forming a sleeve and having a larger internal diameter than the first tube portion 661. The internal diameter of the second tube portions 662, 663 correspond to the external diameter of the upstream and downstream tubes 214, 216. Accordingly, the upstream and downstream tubes 214, 216 are received within the second tube portions 662, 663 but prevented from extending into the first tube portions 660, 661. The upstream and downstream tubes 214, 216 are welded in place within the second tube portions 662, 663.

Figure 11 is a cross-sectional view of a fifth alternative pulsation dampener 718. The reference numerals used to denote the features of the fifth alternative pulsation dampener 718 correspond to those used to denote corresponding features of the pulsation dampener 218, with the addition of a value of 500.

The fifth alternative pulsation dampener 718 corresponds to the pulsation dampener 218 in most respects. However, the fifth alternative pulsation dampener 718 additionally comprises an annular wall 772 that extends around the receptacle 720. The receptacle 720 and the annular wall 772 define an annular or toroidal cavity 774 that extends around the receptacle 720. The cavity 774 is filled with powder. The cavity 774 and powder act as a particle damper. In particular, as fluid passing along the outward conduit 206 changes in pressure, the receptacle 720 cyclically expands and contracts. As the receptacle 720 cyclically expands and contracts, the particles forming the second portion of powder move past each other. Friction between the particles results in the generation of heat. Accordingly, kinetic energy in the form of heat is removed from the component, which causes a reduction in the amplitude of vibration stresses within the component, and fluctuations in pressure of fluid passing along the outward conduit 206 are dampened.

As shown in Figure 11, the first flange 734 and the flange 238 of the upstream tube 214 are provided with through holes 746 through which bolts or screws (not shown) may be inserted to secure the pulsation dampener 718 to the upstream tube 214. Likewise, the second flange 736 and the flange 240 of the downstream tube 216 are provided with through holes 248 through which a further set of bolts or screws (again not shown) may be inserted to secure the pulsation dampener 718 to the downstream tube 216. The flanges of any preceding arrangement may be configured in a similar manner.

Figure 12 shows an apparatus 42 for carrying out a first additive manufacturing (i.e. 3D printing) process 100 (see Figure 13). In the example provided, the first additive manufacturing process 100 is an electron beam melting process. The apparatus 42 comprises a powder hopper 48, a build tank 46 and a platform 50 located within the build tank 46. The powder hopper 48 contains powder 52, which can be conveyed by a levelling mechanism 54 into the build tank 46. An electron beam gun 56 is located above the build tank 46.

Figure 13 shows a flowchart of the first additive manufacturing process 100. In a first step Al of the process 100, powder 52 is conveyed from the powder hopper 48 to the build tank 46 by the levelling mechanism 54. The powder 52 comprises part of a first portion of powder and part of a second portion of powder. In a second step A2 of the process, the electron beam gun 56 generates an electron beam 57 which is directed towards the part of the first portion of powder so as to melt or sinter the part of the first portion of powder. In a third step A3 of the method, the part of the first portion of powder solidifies so as to form part of a solid body. The electron beam 57 is not directed to the part of the second portion of powder, and, thus, the part of the second portion of powder is not melted and remains a powder (i.e. it is unsintered). The second portion of powder is therefore not solidified.

The platform 50 is then actuated downwards and the process described above is repeated. In particular, additional powder 52 is conveyed from the powder hopper 48 to the build tank 46 by the levelling mechanism 54. The additional powder 52 comprises a further part of the first portion of powder and a further part of the second portion of powder. The electron beam gun 56 generates an electron beam 57 which is directed towards the further part of the first portion of powder so as to melt the further part of the first portion of powder. During melting of the further part of the first portion of powder, the further part of the first portion of powder fuses with the previously solidified part of the solid body. The process is carried out layer upon layer. The electron beam 57 is not directed to the further part of the second portion of powder, and, thus, the further part of the second portion of powder is not melted and remains a powder.

Figure 12 shows the apparatus 42 and part of a solid body 55 formed in situ after multiple iterations (i.e. repetitions) of the above mentioned process. The solid body 55 defines an annular open cavity 60 having an annular opening 62 and a spherical open cavity 61 having a circular opening 63. The second portion of powder is located (i.e. disposed, situated or contained) within the cavities 60, 62. Additional powder is located around the solid body 55, outside of the cavities 60, 62.

Figure 14 shows a completed pulsation dampener 718 formed in situ after multiple additional iterations of the above mentioned process. As shown, additional layers of the first portion of powder have been solidified such that the annular opening 62 is occluded. The solid body 55 defines an enclosed annular cavity 60 in which the second portion of powder is located. Accordingly, the second portion of powder is enclosed within the solid body 55. The solid body 55 defines the entirety of the enclosed annular cavity 60. The second portion of powder is densely packed within the annular cavity 60. In some arrangements, the second portion of powder occupies approximately 99% of the volume of the annular cavity 60.

Figure 15 shows an apparatus 80 for carrying out a second additive manufacturing process 102 (see Figure 16). In the example provided, the second additive manufacturing process 102 is a laser engineered net shaping process. The apparatus 80 comprises a deposition head 82 and a substrate 83. The deposition head 82 comprises a powder delivery nozzle 86 and a laser 88 and is able to move relative to the substrate 83.

Figure 16 shows a flowchart of the second additive manufacturing process 102. During a first stage B1 of the manufacturing process 102, the powder delivery nozzle 86 ejects a first portion of powder onto the substrate 83. The laser 88 simultaneously generates a laser beam 59 directed towards the ejected first portion of powder, which melts B2 the ejected first portion of powder. The ejected first portion of powder cools and solidifies B3 to form a solid body. Successive layers of the first portion of powder are built up, with each successive layer fusing with the previous layer of solidified first portion of powder as per the first process 100.

Figure 15 shows the apparatus 80 and a solid body 55 formed in situ after multiple iterations of the above mentioned process. The solid body 55 defines an annular open cavity 92 having an annular opening 84 and a spherical open cavity 93 having a circular opening 85. During the first stage B1 of the second additive manufacturing process 102, the powder delivery nozzle 86 only ejects powder that is subsequently solidified. Accordingly, in contrast to the first additive manufacturing process 100, the cavities 92, 93 are not initially filled with powder.

During the next stage of the second additive manufacturing process 102, the powder delivery nozzle 86 ejects 34 a second portion of powder into the annular cavity 92 via the opening 84. The laser 88 is not activated such that the ejected second portion of powder is not melted and remains in powder form within the cavity 92 (i.e. it is not solidified).

During a further stage of the second additive manufacturing process 102, the powder delivery nozzle 86 ejects B5 a third portion of powder onto the previously solidified first portion of powder. The third portion of powder may be ejected to the opening 84 or over the opening 84. The third portion of powder does not pass completely through the opening 84, and, thus, in contrast to the second portion of powder, is not ejected into the cavity 92. The laser 88 simultaneously generates a laser beam 59 directed towards the ejected third portion of powder, which melts B6 the ejected third portion of powder. The melted third portion of powder fuses with the previous layers of the first portion of powder, cools and solidifies 37 to form part of the single solid body. This process continues until the opening 84 is occluded and the solid body forms an enclosed cavity in which the second portion of powder is located, as shown in Figure 17. The remaining features of the fifth alternative pulsation dampener 718 (e.g. the neck 722, the first tube 724 and the second tube 726) are additively manufactured as described above.

The second portion of powder is less densely packed within the cavity 92 than in the cavity 60 formed by the first additive manufacturing process 100 described above. For example, the second portion of powder may occupy between 75% and 95% of the volume of the cavity 92. A very precise amount of the second portion of powder can be ejected into the cavity 92.

Figure 18 shows a flowchart of a third additive manufacturing process 104, which incorporates steps of the first additive manufacturing process 100 and the second additive manufacturing process 102 referred to above. Steps Cl to C3 of the third additive manufacturing process 104 substantially correspond to steps Al to A3 of the first additive manufacturing process 100. Steps Cl to 03 are carried out so as to produce a solid body formed by a first portion of powder, defining a cavity 60 and having a single opening 62, such as that shown in Figure 12. Steps Cl to 03 produce a solid body having high dimensional accuracy and good surface finish. The solid body is removed from the apparatus 42 and further powder located in the open cavity of the solid body is removed 04 from the cavity 60. The solid body is then placed 05 in the apparatus 80. Steps 06 to 09 of the third additive manufacturing process 104 correspond to steps B4 to B7 of the second additive manufacturing process 102.

Although it has been described that the first additive manufacturing process 100 and the third additive manufacturing process 104 involve electron beam melting to form whole or part of the component from a powder bed, in alternative embodiments a different powder bed additive manufacturing process can be employed instead, such as selective laser melting (SLM), selective laser sintering (SLS) or direct metal laser sintering (DM LS).

Although it has been described that the second additive manufacturing process 102 and the third additive manufacturing process 104 involve laser engineered net shaping to form whole or part of the component, in alternative embodiments a different powder blown powder process can be employed instead, such as direct laser deposition (DLD), direct metal deposition (DMD) or laser metal deposition (LMD).

Such processes may involve sintering or gluing instead of melting.

Although it has been described that a single opening is provided in a solid body which is then occluded, in alternative arrangements two or more openings may be provided which are then occluded.

It will be appreciated that any of the alternative pulsation dampeners 318, 418, 518, 618, 718 may be used in place of the pulsation dampener 218. It will be appreciated that the abovementioned arrangements are only exemplary, that the features described with reference to the pulsation dampeners 218, 318, 418, 518, 618, 718 function independently of each other, and that a pulsation dampener having a different combination of the features described above may be used in place of the specific arrangements described herein.

Although it has been described that the pulsation dampener is used in a fluid conduit of a gas turbine engine, it may alternatively be used in a fluid conduit of other power systems, or be used in nuclear or submarine applications. In the abovementioned arrangements the fluid conduit conveys hydraulic fluid. However, in alternative arrangements the fluid conduit may convey other fluid such as water, oil, ant-icing fluid or fuel.

In the abovementioned arrangements, the pulsation dampeners are additively manufactured from a single material. The material may be titanium, titanium alloy, steel, steel alloy or a nickel-based superalloy, for example. The pulsation dampeners may alternatively be manufactured in a single process from multiple materials.

In any of the arrangements described herein, the connections between the upstream and downstream tubes and the pulsation dampeners may be formed by butt joints such as those described with reference to Figures 5 and 6.

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 pulsation dampener (218, 318, 418, 518, 618, 718) for a fluid conduit (206), the pulsation dampener (218, 318, 418, 518, 618, 718) comprising a receptacle (220, 320, 420, 520, 620, 720), a neck (222, 322, 422, 522, 622, 722), a first tube (224, 324, 424, 524, 624, 724) and a second tube (226, 326, 426, 526, 626, 726), wherein a downstream end of the first tube (224, 324, 424, 524, 624, 724) is fluidically connected to an upstream end of the second tube (226, 326, 426, 526, 626, 726), wherein a first end of the neck (222, 322, 422, 522, 622, 722) is fluidically connected to the downstream end of the first tube (224, 324, 424, 524, 624, 724) and the upstream end of the second tube (226, 326, 426, 526, 626, 726), wherein a second end of the neck (222, 322, 422, 522, 622, 722) is fluidically connected to the receptacle (220, 320, 420, 520, 620, 720), wherein the first tube (224, 324, 424, 524, 624, 724), the second tube (226, 326, 426, 526, 626, 726), the neck (222, 322, 422, 522, 622, 722) and the receptacle (220, 320, 420, 520, 620, 720) are formed as a single unitary component by an additive manufacturing process.
2. The pulsation dampener (318, 418, 518, 718) of claim 1, wherein an upstream end of the first tube (324, 424, 524, 724) comprises a first radially extending flange (334, 434, 534, 734) for connection to an upstream tube of the fluid conduit (206) and the downstream end of the second tube (326, 426, 526, 726) comprises a second radially extending flange (336, 436, 536, 736) for connection to a downstream tube of the fluid conduit (206), wherein the first radially extending flange (334, 434, 534, 734) and the second radially extending flange (336, 436, 536, 736) are formed as part of the single unitary component by the additive manufacturing process.
3. The pulsation dampener (618) of claim 1, wherein an upstream end of the first tube (624) comprises a first sleeve portion (662) for receiving an upstream tube (214) of the fluid conduit (206) and wherein a downstream end of the second tube (626) comprises a second sleeve portion (663) for receiving a downstream tube (216) of the fluid conduit (206), wherein the first sleeve portion (662) and the second sleeve portion (663) are formed as part of the single unitary component by the additive manufacturing process.
4. The pulsation dampener (218) of claim 1, wherein an upstream end of the first tube (224) is welded to an upstream tube (214) of the fluid conduit (206) so as to form a first butt joint and wherein a downstream end of the second tube (226) is welded to a downstream tube (216) of the fluid conduit (206) so as to form a second butt joint.
S. The pulsation dampener (218, 318, 418, 518, 618, 718) of any preceding claim, wherein the neck (222, 322, 422, 522, 622, 722) is connected to the receptacle (220, 320, 420, 520, 620, 720) by a fillet (242, 342, 442, 542, 642, 742) and/or wherein the neck (222, 322, 422, 522, 622, 722) is connected to the first and second tubes (226, 326, 426, 526, 626, 726) by a fillet (244, 344, 444, 544, 644, 744), wherein the fillets (242, 342, 442, 542, 642, 742, 244, 344, 444, 544, 644, 744) are formed as part of the single unitary component by the additive manufacturing process.
6. The pulsation dampener (218, 318, 418, 518, 618, 718) of claim 5, wherein each fillet (242, 342, 442, 542, 642, 742, 244, 344, 444, 544, 644, 744) has a radius of curvature of between 0.5 and 10 millimetres.
7. The pulsation dampener (218, 318, 418, 518, 618, 718) of any preceding claim, wherein the thickness of a wall defining the neck (222, 322, 422, 522, 622, 722) and/or the first tube (224, 324, 424, 524, 624, 724) and/or the second tube (226, 326, 426, 526, 626, 726) is greater than the thickness of a wall defining the receptacle (220, 320, 420, 520, 620, 720).
8. The pulsation dampener (318) of any preceding claim, wherein the longitudinal axis (330) of the first tube (324) is angled with respect to the longitudinal axis (332) of the second tube (326).
9. The pulsation dampener (318) of any preceding claim, wherein none of the longitudinal axis (330) of the first tube (324), the longitudinal axis (332) of the second tube (326) and the longitudinal axis (328) of the neck (322) are coplanar.
10. The pulsation dampener (418) of any one of claims 1 to 7, wherein the longitudinal axis (430) of the first tube (424) is parallel to the longitudinal axis (432) of the second tube (426).
11. The pulsation dampener (218, 518, 618, 718) of any one of claims 1 to 7, wherein the longitudinal axis (230, 530, 630, 730) of the first tube (224, 524, 624, 724) and the longitudinal axis (232, 532, 632, 732) of the second tube (226, 526, 626, 726) are coaxial
12. The pulsation dampener (218, 318, 418, 518, 618, 718) of any preceding claim, wherein the first tube (224, 324, 424, 524, 624, 724) and the second tube (226, 326, 426, 526, 626, 726) have a circular cross-sectional profile, and wherein the diameter of the first tube (224, 324, 424, 524, 624, 724) is greater than or less than the diameter of the second tube (226, 326, 426, 526, 626, 726).
13. The pulsation dampener (518) of any preceding claim, wherein at least a portion of the first tube (524) and/or the second tube (526) is corrugated (564, 570) so as to increase its flexibility.
14. The pulsation dampener (218, 318, 418, 518, 618 718) of any preceding claim, wherein the receptacle (220, 320, 420, 520 620, 720) is spherical or cylindrical.
15. The pulsation dampener (718) of any preceding claim, further comprising a particle damper (772) coupled to the receptacle (720), wherein the particle damper (772) comprises a cavity (774) containing powder.
16. The pulsation dampener (718) of claim 15, wherein the cavity (774) of the particle damper (772) is defined by an annular wall that extends around the receptacle (720), wherein the annular wall is formed as part of the single unitary component by the additive manufacturing process.
17. A gas turbine engine (10) for an aircraft, the gas turbine engine comprising: 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; 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 a pulsation dampener (218, 318, 418, 518, 618, 718) according to any preceding claim.
18. A method of manufacturing a pulsation dampener (218, 318, 418, 518, 618, 718) as claimed in any of claims 1 to 16, the method comprising the steps of: providing (Al) a powder bed comprising a first portion of powder and a second portion of powder; and solidifying (A3) the first portion of powder so as to form a single unitary solid body (55), the single unitary solid body (55) comprising the receptacle (220, 320, 420, 520, 620, 720), the neck (222, 322, 422, 522, 622, 722), the first tube (224, 324, 424, 524, 624, 724) and the second tube (226, 326, 426, 526, 626, 726).
19. A method of manufacturing a pulsation dampener (218, 318, 418, 518, 618, 718) as claimed in any of claims 1 to 16, the method comprising the steps of: ejecting (Si) a portion of powder; solidifying (B3, B7) the portion of powder so as to form a single unitary solid body (55), the single unitary solid body (55) comprising the receptacle (220, 320, 420, 520, 620, 720), the neck (222, 322, 422, 522, 622, 722), the first tube (224, 324, 424, 524, 624, 724) and the second tube (226, 326, 426, 526, 626, 726).
20. A method of manufacturing a pulsation dampener (218, 318, 418, 518, 618, 718) as claimed in any of claims 1 to 16, the method comprising the steps of: providing a powder bed comprising a first portion of powder; solidifying (C3) the first portion of powder so as to form part of a single unitary solid body (55), the part of the single unitary solid body (55) defining an open cavity (92) having one or more openings (84) into the open cavity; ejecting (C6) a second portion of powder into the open cavity (92) via the one or more openings (84) so as to at least partially fill the open cavity (92) with the second portion of powder; ejecting (07) a third portion of powder; and solidifying (09) the third portion of powder so as to occlude the one or more openings (84) of the open cavity (92) and form the single unitary body (55), the single unitary body (55) having an enclosed cavity (92) in which the second portion of powder is located, wherein the second portion of powder is not solidified, and wherein the single unitary solid body (55) comprises the receptacle (220, 320, 420, 520, 620, 720), the neck (222, 322, 422, 522, 622, 722), the first tube (224, 324, 424, 524, 624, 724) and the second tube (226, 326, 426, 526, 626, 726).