INSPECTION AND MAINTENANCE APPARATUS

Abstract

The present disclosure relates to the inspection and repair/maintenance of an item such as a gas turbine engine. Apparatus (110) is provided for connecting apertures (124,142) in an item to be inspected. The apparatus (110) comprises a tubular guide (130) with first and second ends (134,136) and a hollow interior (138) for receiving an inspection tool, and a housing fixture (120) for mounting the tool to an outer shell (126) of the item. The apparatus (110) provides an articulated joint between the tubular guide (130) and the housing fixture (120). A cooling system may also be included.

Claims

1. Inspection and maintenance apparatus for connecting apertures in an article to be inspected, the article comprising an outer shell having a first aperture therein, and an internal part, located within the outer shell, and having a second aperture therein, the apparatus comprising a tubular guide having a straight elongate body with first and second ends and a hollow interior for receiving an inspection tool, and a housing fixture for mounting the tool to the outer shell, wherein the first end of the tubular guide is received and retained within the housing fixture to provide an articulated joint between the tubular guide and the housing fixture, and the second end of the tubular guide is insertable, in use, through the first aperture, and is engageable with the second aperture provided in the internal part.

2. Inspection and maintenance apparatus according to claim 1, wherein a fluid flow passage is provided around the hollow interior of the tubular guide for cooling the apparatus.

3. Inspection and maintenance apparatus according to claim 2, wherein the tubular guide comprises an inner wall defining the hollow interior, and an outer wall spaced from the inner wall to provide an annular space, wherein the fluid flow passageway is provided between the inner and outer walls.

4. Inspection and maintenance apparatus according to claim 2, wherein the tubular guide comprises a helical fluid flow passageway around the hollow interior.

5. Inspection and maintenance apparatus according to claim 3, wherein the fluid flow passageway comprises a micro porosity structure.

6. Inspection and maintenance apparatus according to claim 5, further comprising a vapour passageway.

7. Inspection and maintenance apparatus according to claim 6, wherein the vapour passageway is provided within the fluid flow passageway.

8. Inspection and maintenance apparatus according to claim 6, wherein the vapour passageway and the fluid flow passageway are distinct.

9. Inspection and maintenance apparatus according to claim 8, wherein the vapour passageway comprises a micro lattice internal structure.

10. Inspection and maintenance apparatus according to claim 1, wherein the housing fixture comprises a micro porosity and/or a micro lattice internal structure.

11. Inspection and maintenance apparatus according to claim 5, wherein the internal structure is constructed through additive manufacturing.

12. Inspection and maintenance apparatus according to claim 1, wherein the housing fixture comprises a chamber for containing fluid, and wherein the first end of the tubular guide comprises an opening to the fluid flow passage, the opening being received within the chamber.

13. Inspection and maintenance apparatus according to claim 12, wherein the housing fixture comprises a port to allow fluid to enter and/or leave the apparatus.

14. Inspection and maintenance apparatus according to claim 1, wherein the first end of the tubular guide is substantially spherical, and the housing fixture comprises a substantially spherical hole for receiving the first end of the tubular guide.

15. Inspection and maintenance apparatus according to claim 1, wherein the first end of the tubular guide has a substantially tubular shape, and the housing fixture comprises a substantially tubular hole for receiving the first end of the tubular guide.

16. Inspection and maintenance apparatus according to claim 1, wherein the first end of the tubular guide has a substantially elliptical shape, and the housing fixture comprises a substantially elliptical hole for receiving the first end of the tubular guide.

17. Inspection and maintenance apparatus according to claim 1, wherein the second end of the tubular guide is substantially elliptical.

18. A gas turbine engine (10) for an aircraft 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; and 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, a housing fixture mounted to an outer shell of the engine (10), and a tubular guide having a straight elongate body with first and second ends and a hollow interior for receiving an inspection tool, wherein the first end of the tubular guide is received and retained within the housing fixture to provide an articulated joint between the tubular guide and the housing fixture, and the second end of the tubular guide is insertable, in use, through the first aperture, and is engageable with a second aperture provided in an internal part of the engine.

19. The gas turbine engine according to claim 18, wherein the first and second apertures are borescope ports.

20. The gas turbine engine according to claim 18, 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.

Description

DESCRIPTION OF THE DRAWINGS

[0056] Embodiments will now be described by way of example only, with reference to the Figures, in which:

[0057] FIG. 1 is a sectional side view of a gas turbine engine;

[0058] FIG. 2 is a close up sectional side view of an upstream portion of a gas turbine engine;

[0059] FIG. 3 is a partially cut-away view of a gearbox for a gas turbine engine;

[0060] FIG. 4 shows a borescope port plug received in the concentric borescope ports of a gas turbine engine;

[0061] FIG. 5 shows a borescope port plug received in non-concentric borescope ports of a gas turbine engine;

[0062] FIG. 6 shows a guide system provided between two non-concentric ports;

[0063] FIG. 7 is a detail view of a guide system similar to that shown in FIG. 6;

[0064] FIG. 8 is a detail view of an alternative guide system;

[0065] FIG. 9A is a schematic view of part of an alternative guide system; and

[0066] FIG. 9B is a schematic view of part of a further alternative guide system.

DETAILED DESCRIPTION

[0067] FIG. 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.

[0068] 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.

[0069] An exemplary arrangement for a geared fan gas turbine engine 10 is shown in FIG. 2. The low pressure turbine 19 (see FIG. 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.

[0070] 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.

[0071] The epicyclic gearbox 30 is shown by way of example in greater detail in FIG. 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 FIG. 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.

[0072] The epicyclic gearbox 30 illustrated by way of example in FIGS. 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.

[0073] It will be appreciated that the arrangement shown in FIGS. 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 FIG. 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 FIG. 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 FIG. 2.

[0074] 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.

[0075] Optionally, the gearbox may drive additional and/or alternative components (e.g. the intermediate pressure compressor and/or a booster compressor).

[0076] 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 FIG. 1 has a split flow nozzle 20, 22 meaning that the flow through the bypass duct 22 has its own nozzle that is separate to and radially outside the core engine 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.

[0077] 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 FIG. 1), and a circumferential direction (perpendicular to the page in the FIG. 1 view). The axial, radial and circumferential directions are mutually perpendicular.

[0078] Aeroengine borescope ports commonly comprise a hole in the outer casing of the engine and one or more holes in the inner casing(s) and/or components. In many cases, these holes are aligned or concentric, as shown in FIG. 4. The specific arrangement shown comprises an outer hole 102 in the outer casing 103, and a concentric inner hole 104 through an inner component 105 of the engine. The arrangement of FIG. 4 additionally comprises an additional hole 106, concentric with the inner and outer holes 102,104, provided in the heatshield 107.

[0079] During engine running, these holes 102,104,106 house a borescope port plug 108, which is designed to restrict the air flow from the gas path to the casings. The concentricity of the outer and inner holes 102,104 also enables easy deployment of an inspection or repair system. For example, a rigid inspection borescope or a mechanical boreblender can be inserted to perform on-wing inspection and repair work. Moreover, an embedded optical inspection system (commonly referred to as Engine CCTV) can be inserted between these holes 102,104, such that it plugs the gas path air when stowed and inspects the gas path components when actuated.

[0080] There are some borescope ports in aeroengines that do not have concentric outer and inner holes. FIG. 5 shows an example of this arrangement. Again, outer and inner holes 112,114 are provided, but their axes are offset. The additional hole 116 through the heatshield 117 in FIG. 5 is axially offset from both the outer hole 112 and the inner hole 114.

[0081] It can be seen that the borescope plug 108 is designed to accommodate offset to some extent (the body of the plug 108 pivots at the base and thus enables the non-concentric holes to be plugged). However, the non-concentric nature of the holes 112,114,116 effectively restricts the type, size, and features of device that can be deployed to perform inspection or repair activities. For example, a rigid optical borescope or mechanical boreblending tool needs to be inserted off-perpendicular, which will affect the stand-off distance achieved at the distal tip. Flexible videoscopes can navigate successfully between the outer and inner holes 112,114, but achieving a repeatable standoff distance (and thus inspection quality) is challenging. For more sophisticated inspection or repair systems, such as embedded cameras for automated in-situ inspection, non-concentric borescope ports prove problematic, especially when trying to achieve repeatable actuation to look exactly side-on at the neighbouring components.

[0082] Hence, an approach is required to physically bridge the gap between the outer and inner borescope port holes such that an inspection or repair system can be repeatedly and accurately inserted.

[0083] The high operating temperatures of gas turbines also lead to a desire for thermal management of inspection or repair tools during use. Probes or other tools may need to be cooled in order to survive high engine temperatures. FIG. 6 shows an example system, applied to a gas turbine engine. The system or tool 110 is divided in two main components, the first one of which is a housing fixture 120 with a spherical hole 122 in the centre. The housing fixture 120 is located within a first opening 124 in the outer casing 126 of the engine, and is fixed to the outer casing 126. As illustrated, bolt holes 128 are provided in the housing fixture 120. The spherical hole 122 in the housing fixture 120 allows to the second component, the guiding tube 130, to be attached.

[0084] The guiding tube 130 comprises a straight tube 132 with a first end 134 in the shape of a sphere and a second end 136 in the shape of an ellipse or a sphere. The first end 134 is attached into the housing fixture, thus constructing a spherical joint, and the second end 136 is received in an opening 142 in the inner casing 140 of the engine. The design of an oval or spherical second end 136 helps to avoid fluid leaks regardless of the angle of the guiding tube 130 relative to the opening 142.

[0085] The first and second openings 124,142 may be borescope ports provided in the gas turbine engine. The guiding tube 130 has a hollow interior 138 to create a straight path for an inspection instrument or tool (e.g. an embedded optical inspection system), regardless of the lack of concentricity of the two borescope holes 124,142.

[0086] The spherical joint provided by the spherical hole 122 in the housing fixture 120 and the first end 134 of the guiding tube 130 effectively provides an articulated joint in the apparatus. The articulation helps to allow a free-range movement of the guiding tube 130 as illustrated in FIGS. 8 and 9. This in turn helps to provide a single design of guiding system suitable for several different misaligned borescopes or similar, regardless of the concentricity error.

[0087] The structure of one example of the guiding tube 130 is shown in FIG. 7. The guiding tube 130 is constituted by an inner wall 150 that travels across the entire length of the tube 130, and an outer wall 151 forming the exterior of the guiding tube 130, including the spherical first end 134 and oval second end 136. The first end 134 may be considered an articulation end, and the second end 136 a sealing end. An annular region 152 is provided between the inner and outer walls 150,151 to allow the passage of fluid and vapour to remove heat from the environment, thus protecting equipment received in the hollow interior 138 of the tube 130.

[0088] The faces of the inner and outer walls 150,151 that define the annular region 152 are provided with a porous structure 153 through which fluid permeates. In use, heat from a hot region surrounding the straight tube 132 heats and ultimately evaporates the fluid held in this porous structure 153. The resulting vapour then passes through the open part 154 of the annular region 152 removing heat from the system. The tube 130 can thus be considered a thermal management sleeve, specifically a heat pipe, using the process of evaporation and condensation to cool an inspection tool such as a rigid inspection probe. This can help to maintain the tool below a predetermined temperature, for example below its storage temperature, during use.

[0089] The porous structure 153 could otherwise be implemented by way of grooves or other similar structure that provides capillary force on a fluid.

[0090] The annular region 152 is designed to be completely sealed on the guiding tube 130, except where the interface 155 of the guiding tube 130 and the housing fixture 120 occurs. An arrow 156 is provided to illustrate the movement/articulation provided at the first end of the guiding tube 130 within the housing fixture 120.

[0091] The housing fixture 120 also comprises an exterior structural wall 160 and an interior porous region 162 that retains fluid like a sponge. The fluid can move from the porous region 162 of the housing fixture 120 through the porous structure 153 of the guiding tube 130 via capillary action, to permeate/flow around the system 110.

[0092] The porous region 162 also provides a cold zone remote from the tube 130 and the opening 124. When the fluid that runs in the porous structure 153 is at the hot zone, the fluid evaporates and enters region 154 and the natural pressure differential formed in the system then moves the vapour to the cold zone where it condenses. One or more open passages or vapour gaps 157 are provided in the porous/grooved region 162 to allow the vapour to pass to the cold zone. The vapour then condenses and seeps into the porous region 162, from where it moves back to the porous structure 153 of the tube by capillary action. The condensation process may happen away from opening 124, and could incorporate a heat sink, or other architecture to improve the efficiency of the condensation process.

[0093] The interior region 162 is also largely sealed, except at the interface 155 between the guiding tube and the housing fixture 120. A designed escape (not shown) may also be provided to allow fluid to leave and enter the system 110. The porous region 162 is a large structure such that it can maintain contact with the porous region at the interface 155 regardless of the angle of the tube 130.

[0094] The internal fluid region/reservoir 162 can be designed and constructed through additive manufacturing to better allow the fluid to pass. Due to the capacity of additive manufacturing, the tube 130 and the housing fixture 120 can be manufactured together. Examples of possible internal fluid structures include a micro porosity or a micro lattice/groove structure, either or both of which can be produced using a process of additive manufacturing.

[0095] To better direct the passage of fluid inside the system 110, the internal structure of the guiding tube 130 can comprise an internal helix 170 to create an open fluid loop with one entry in a specific region of the housing fixture 120 and an exit on another region of the same housing fixture 120. An example of this loop heat pipe approach is shown in FIG. 8. The helix design 170 allows for the system to be fully optimized for the direction of flow, depending on the heat of the fluid. For example, a porous/grooved region 172 can be used to retain and direct liquid into the system 110 for cooling. Additionally, or alternatively, a lattice structure 174 can be used to better direct the vapour out of the system 110, removing the heat. The fluid passes into the hot zone and evaporates, and the vapour then passes through a dedicated vapour tube to condense in a cold zone. The porous region 172 and/or lattice structure 174 can be produced using a process of additive manufacturing.

[0096] It should be understood that an articulated joint could be provided by providing a first end 134 that is not spherical as described above. For example, FIG. 9A shows a section of straight tube 132 of an alternative guiding tube 130 provided with a cylindrical first end 234. The cylindrical first end 234 would cooperate with a similarly shaped in a housing fixture 120. FIG. 9B shows a further example of an elliptically shaped first end section 334 to correspond with a larger elliptical hole in the housing fixture 120.

[0097] These and other possible alternative shapes can still give flexibility and protection for the thermal management of systems in concentric borescopes, as the thermal expansion on the casing will be taken by the joint, not by the compression of the guiding tube. However, they can also restrict and/or increase the movement of the guiding tube in one or more particular directions as desired. For example, it might be beneficial to allow for more movement on the radial direction of an engine, and at the same time it might be best to restrict this movement on the axial direction.

[0098] The system as described allows a thermally managed probe to be deployed into a non-concentric borescope port. Without the articulating joint design provided between the first end of the guide tube and the housing fixture, problems may be encountered where a probe simply cannot be deployed into such ports or the probe would need to be flexible to curve between the two non-concentric holes. Flexible probes are less preferred, because they do not allow a fixed stand-off distance to the component being inspected. This affects the ability of a related algorithm to assess the outputted inspection images.

[0099] The articulation of the system helps to accommodate any changes in hole alignment due to thermal expansion and/or contraction during engine running. In situations where inspection is carried out while a gas turbine is running, for example on-wing inspection or measurement performed on an aeroengine, thermal expansion and contraction could damage or break a rigid inspection tool and/or engine components constrained by a rigid, immovable, connection. The arrangement therefore has benefits for concentric, as well as for non-concentric, borescope ports. The ends of the guiding tube, along with the articulation at the first end, help to provide a versatile/universal system that can accommodate various degrees of spacing between the axes of non-concentric holes. Therefore, one system is suitable for use in various situations having concentric holes and/or differently spaced non-concentric holes.

[0100] The system also helps, in general, to thermally manage a probe or inspection tool in a hot environment. It can thus be applied to any number of industrial fields, in addition to aeroengines as discussed above. These include, but are not limited to, marine and industrial gas turbines, and nuclear or steel production environments, where remote visual inspection via an embedded probe is required.

[0101] 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.