Gas turbine engine component particle sampling apparatus, system and method

Abstract

A particulate sample collector for collecting particulate samples deposited on a surface of a gas turbine engine component. The particle sample collector includes a collection medium support including a support surface that supports a collection medium between an inlet of the particle sample collector and an outlet of the particle sample collector. An inlet is included within the hollow body. The inlet and the outlet are fluidly coupled. The outlet is included within the hollow body or within the collection media support. The gas stream carrying the particulate sample enters the particulate sample collector at the inlet such that the collection medium collects the particulate sample. The gas stream then exits the particulate sample collector at an outlet.

Description

Technical Field

[0001] The present disclosure relates to an apparatus and method for collecting particulate matter accumulated on the surface of a component of a gas turbine engine. Background Art

[0002] Gas turbine engines for propulsion or power generation purposes must operate under a range of different atmospheric conditions. The atmospheric conditions may include various airborne contaminants in gaseous, liquid, and solid forms and in different concentrations.

[0003] It is known that solid contaminants can adhere to the air-scavenged surfaces of a gas turbine engine, and it is known that the accumulation of these contaminants can lead to both a degradation of the engine's efficiency and a shortening of the life of engine components. In the worst case, this can lead to the premature removal of the engine from its installation location for refurbishment.

[0004] It is also known that the rate of degradation of engine efficiency can be at least partially mitigated by applying a surface coating to the affected components or by redesigning the components. However, both coating and / or component redesign are expensive options, which means that it is desirable to use these options only in the areas of the gas turbine engine where performance degradation is most likely to occur.

[0005] Accordingly, there is a need for an apparatus that enables samples of particulate matter covering the surface of a component of a gas turbine engine to be obtained, and a method for obtaining such samples. Summary of the Invention

[0006] According to a first aspect, there is provided a particulate sample collector for collecting a particulate sample deposited on the surface of a component of a gas turbine engine. The particulate sample collector includes a collection medium support member that includes a support surface that supports a collection medium located between an inlet of the particulate sample collector and an outlet of the particulate sample collector. The inlet is included within a hollow body. The outlet is included within the hollow body or within the collection medium support member. The inlet and the outlet are fluidly coupled. An airflow carrying the particulate sample enters the particulate sample collector at the inlet such that the collection medium collects the particulate sample. The airflow then exits the particulate sample collector at the outlet.

[0007] A first seal may be provided at a first interface between the hollow body and the collection medium support member. The first seal may include an elastomer.

[0008] The outlet of the particulate sample collector may be capable of being connected to a vacuum source that creates at least a partial vacuum within the hollow body such that the airflow and the particulate sample carried by the airflow enter the particulate sample collector via the inlet.

[0009] A second seal may be provided at a second interface between the outlet of the particulate sample collector and the vacuum source.

[0010] The support surface can be porous or perforated.

[0011] The collection medium can be configured to collect particles having a characteristic particle size greater than 0.001 micrometers (e.g., 0.1 micrometers or 0.2 micrometers).

[0012] The velocity of the gas stream carrying the particle sample at the inlet can be at least 0.1 m / s.

[0013] The hollow body can include a nozzle. The inlet can be located at the tip of the nozzle. The tip of the nozzle can be inclined at an angle with respect to the main axis of the particle sample collector. In some instances, the angle can be between 5° and 85°, e.g., 30° to 60°. The tip of the nozzle can include a scraper surface.

[0014] The inlet can be configured to connect to the first end of a tube. The tube can have a second nozzle at its second end or be configured to connect to a second nozzle at its second end. The second nozzle can have a scraper surface at its tip. The tip of the second nozzle can be inclined at an angle with respect to the main axis of the second nozzle.

[0015] The tube can be flexible. The tube can be part of a borescope or be capable of connecting to a borescope.

[0016] The particle sample collector can be formed by an additive manufacturing process or can be formed by injection molding.

[0017] According to a second aspect, a method for determining the composition of particle residues on the surface of a gas turbine engine component is provided. The method includes obtaining a particle sample from the surface of the gas turbine engine component using a particle sample collector as disclosed in the foregoing paragraphs relating to the first aspect, and analyzing the particle sample to determine the composition of the particle residues.

[0018] Analyzing the particle sample can include at least one of the following: X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) analysis, energy-dispersive X-ray (EDX) analysis, wet chemical analysis, particle size distribution (PSD) analysis, inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), electron probe, isotope analysis, and / or differential scanning calorimetry (DSC).

[0019] The method can further include determining the suitability of the material forming the surface of the gas turbine engine component (e.g., the surface coating of the gas turbine engine component) based on the analysis of the particle sample, or modifying the design features of the gas turbine engine based on the analysis of the particle sample.

[0020] According to a third aspect, there is provided a system for collecting a particulate sample deposited on the surface of a component of a gas turbine engine. The system includes a particulate sample collector, a tube, and a vacuum source as disclosed with respect to the first aspect. The vacuum source is connected to the outlet of the particulate sample collector. The tube is connected to the inlet of the particulate sample collector at its first end. Due to the action of the vacuum source, a particulate sample is obtained at the second end of the tube. The tube may be attachable to a borescope or may be included within a borescope.

[0021] As used herein, the term "characteristic grain size" refers to an idealized spherical particle having a certain diameter (characteristic dimension) whose resulting volume is equal to the volume of an actual particle that is not spherical but is to some extent elongated (one dimension being greater than the other) and / or has a wavy surface profile.

[0022] Similarly, the term "characteristic aperture" may be used with respect to a collection medium to recognize that the voids (pores) within the collection medium may not be spherical but may have unequal dimensions and / or a wavy inner surface.

[0023] Within the scope of this document, the term "major axis" is defined as the axis about which an object is axisymmetric.

[0024] Those skilled in the art will understand that, unless mutually exclusive, the features described with respect to any of the above aspects may be applied, with necessary modifications, to any other aspect. Additionally, unless mutually exclusive, any feature described herein may be applied to any aspect and / or combined with any other feature described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional side view of a gas turbine engine; Figure 2 is a schematic view of a first embodiment of a particulate sample collector; Figure 3a is a schematic view of a second embodiment of a particulate sample collector; Figure 3b is along Figure 3a view A-A of; Figure 4 is an example of a system including an exemplary particulate sample collector; Figure 5a is a schematic view of a nozzle and a flexible conduit coupled to a particulate sample collector; Figure 5b is along Figure 5a view along arrow C of; and Figure 6An example method of use in combination with a particulate sample collector. Detailed Description

[0026] Aspects and embodiments of the present disclosure will now be described with reference to the accompanying drawings. Other aspects and embodiments will be apparent to those skilled in the art.

[0027] Referring to Figure 1 , a gas turbine engine is generally designated 10 and has a main axis and a rotational axis 11. The engine 10 includes, in axial series, an air intake 12, a propulsion fan 13, a medium-pressure compressor 14, a high-pressure compressor 15, a combustion device 16, a high-pressure turbine 17, a medium-pressure turbine 18, a low-pressure turbine 19, and an exhaust nozzle 20. A nacelle 21 generally surrounds the engine 10 and defines both the air intake 12 and the exhaust nozzle 20.

[0028] The gas turbine engine 10 operates in a conventional manner such that air entering the air intake 12 is accelerated by the fan 13 to produce two airflows: a first airflow (core airflow) entering the medium-pressure compressor 14, and a second airflow (bypass airflow) passing through a bypass duct 22 to provide propulsion thrust. The medium-pressure compressor 14 compresses the airflow directed into it and then delivers this air to the high-pressure compressor 15 for further compression.

[0029] The compressed air discharged from the high-pressure compressor 15 is directed into the combustion device 16 where it is mixed with fuel and the mixture burns. The resulting hot combustion products then expand through and thereby drive the high-pressure turbine 17, the medium-pressure turbine 18, and the low-pressure turbine 19, and then are discharged through the nozzle 20 to provide additional propulsion thrust. The high-pressure turbine 17, the medium-pressure turbine 18, and the low-pressure turbine 19 respectively drive the corresponding high-pressure compressor 15, the medium-pressure compressor 14, and the fan 13 via suitable interconnecting shafts.

[0030] 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 interconnecting shafts (e.g., two) and / or an alternative number of compressors and / or turbines. Additionally, the engine may include a gearbox disposed in the drivetrain from the turbine to the compressor and / or the fan.

[0031] Since a gas turbine engine is a jet engine, the components of the gas turbine engine are exposed to contaminants present in the atmosphere, which may have a harmful effect on these components.

[0032] Contaminants may include aerosol minerals and / or volcanic ash.

[0033] Aerosol minerals can also be referred to as mineral dust. Aerosol minerals include tiny (usually less than 100 microns in diameter) fragmented rock particles that are suspended in the air by the action of wind. Aerosol particles are usually of a crystalline nature.

[0034] Volcanic ash consists of particles of a similar size to aerosol minerals (usually less than 100 microns in diameter), which are also suspended in the air. Volcanic ash originates from volcanic eruptions during which lava solidifies rapidly in the volcanic crater or in the atmosphere to form particles including amorphous glass solids. The particles of volcanic ash may also include some solid crystal fragments present in the rock during the volcanic eruption. Volcanic ash can have a glass content between 20% and 100%.

[0035] Pollutants can form deposits, such as particulate matter on the surface of components of a gas turbine engine. Particulate matter can also be referred to as dust.

[0036] Particulate matter can include a range of different particle sizes.

[0037] The characteristic particle size of at least one subset of the particulate matter can be at least 0.2 microns, and the subset of the particulate matter corresponds to a particulate matter sample (particle sample) to be collected.

[0038] The degree of harmful effects that can occur depends on a variety of factors, including the chemical and physical properties of the pollutants, the temperature of the components in contact with these pollutants, the material of the components being manufactured (or the coating on the components), and the concentration of these pollutants within the gas turbine engine.

[0039] For example, since the core of a gas turbine engine that receives the core air flow operates at a significantly higher peak temperature than the bypass duct, the core components of the gas turbine engine are more likely to be damaged by contamination than the bypass duct components.

[0040] Since the core of a gas turbine engine includes turbomachinery that rotates at high speeds, when the gas turbine engine is operating, a strong centrifugal force is generated within its secondary air flow, which means that as the particles suspended in the air move forward through the intermediate compressor and possibly through the downstream high-pressure compressor, the size distribution of the particles suspended in the air entering the inlet of the intermediate compressor may change according to the radial duct height. For example, larger particles are more likely to be centrifuged radially outwards than smaller particles as they pass through the compressor of the gas turbine engine.

[0041] Smaller particles that are more easily carried by the air flow can be extracted from the main gas path of the core gas turbine engine through radially inner exhaust ports, which are used to supply air to the secondary air system of the gas turbine engine, for example, for engine cooling, bearing sealing, or bearing load management.

[0042] However, as long as there is contact between the contaminant and the surface of the air-scoured portion of the gas turbine engine component, residues of the contaminant may remain on that surface. The air-scoured portion of the gas turbine engine component may be located in the primary gas path of the gas turbine engine (e.g., on the aerodynamic surfaces of the blades of the propulsion fan 13, compressors 14, 15 or turbines 17, 18, 19), or may be located on a surface exposed to an air flow drawn from the exhaust outlet of the primary gas path (e.g., the air-scoured portion of the gas turbine engine component may form part of the air system of the gas turbine engine).

[0043] It will be appreciated from the above discussion that the nature of the residues (i.e., their chemical composition and / or particle size distribution) may vary within different parts of the gas turbine engine.

[0044] It will be appreciated from the above disclosure that mapping which regions of the gas turbine engine collect what form of particles can be beneficial. This is because, with this knowledge, gas turbine engine manufacturers can selectively apply protective coatings to affected gas turbine engine components. Different surface coatings can be applied to different components, depending on the type and concentration of residues (particles) that may accumulate during their use.

[0045] By selectively applying coatings, gas turbine engine manufacturers may thus be able to reduce the cost of engine components and / or simplify the manufacturing process and / or the supply chain for sourcing gas turbine engine components.

[0046] This disclosure relates to how samples (particle samples) of such particulate matter can be collected from a gas turbine engine, and subsequent analysis of such particles.

[0047] Samples can be collected when the engine is not operating (i.e., when the gas turbine is shut down and the turbomachinery components of the gas turbine engine are not rotating).

[0048] Samples can be collected during engine assembly.

[0049] For example, samples can be collected from the surfaces of gas turbine engine components that are easily accessible to the user when the engine is not operating.

[0050] Examples of such components include the spinner of the gas turbine engine, the fan blades of the gas turbine engine, or the air-scoured panel within the bypass duct of the gas turbine engine.

[0051] Samples can be collected during engine assembly by removing the pipe mirror port from the casing of the gas turbine engine. In this way, samples can be taken, for example, from the surfaces of the compressor rotor blades, compressor stator guide vanes, turbine rotor blades, turbine stator guide vanes, exhaust ports within the medium-pressure compressor or high-pressure compressor, exhaust valve ports, etc.

[0052] Alternatively, a sample may also be obtained when the gas turbine engine is disassembled.

[0053] For example, the gas turbine engine may be a pre-production prototype that has been disassembled into its component parts, or it may be a mass-produced engine that has been disassembled into its component parts and retired from an airline. Inspecting the components of the disassembled (removed) engine may be desirable because parts of the components of the gas turbine engine that may not be easily accessible by borescope inspection may be reached. For example, all parts of the components including the secondary air system of the gas turbine engine may be reached.

[0054] The particulate sample is obtained via a particulate sample collector 30. The particulate sample collector 30 collects a particulate sample 81 from the particulate matter deposited on the surface of the components of the gas turbine engine.

[0055] The particulate sample collector 30 may be referred to as the particulate sample collector 30 for the components of the gas turbine engine, or, for the sake of brevity in this text, may be referred to as the collector 30.

[0056] Various forms of particulate sample collectors 30 for collecting particulate samples deposited on the surface of the components of the gas turbine engine are envisioned, with a first example shown in Figure 2 as follows.

[0057] Figure 2 The particulate sample collector 30 of

[0058] includes a hollow body 40 that includes an inlet 45. Figure 2 The hollow body may be axisymmetric about a main axis 35 (as shown in

[0059] ). Alternatively, the hollow body may have any suitable cross-section. For example, the hollow body may have a polygonal cross-sectional area, such as a rectangular or square cross-section. Figure 2 as shown in

[0060] If the hollow body 40 includes a nozzle 44, the inlet 45 is located at the tip of the nozzle 41.

[0061] In the nozzle, starting from the inlet 45, there is a continuous (i.e., non-discrete) and gradually increasing cross-sectional area, with the cross-sectional area of the hollow body being the smallest at the inlet.

[0062] If the hollow body does not include a nozzle 44, there may be a discontinuous change in cross-sectional area, such as a stepped change, between the inlet 45 and the cross-sectional area of the hollow body. Figure 4 An example of such a stepped change is shown in

[0063] The particle sample collector 30 further includes an outlet 50 that is fluidly coupled to the inlet 45.

[0064] In Figure 2 an example, the outlet 50 does not form part of the hollow body 40, but instead is part of a collection medium support 60 that mates with the hollow body 40.

[0065] A first interface 42 may be provided between the hollow body 40 and the collection medium support 60. A first seal 41 may be provided at the first interface 42.

[0066] The first interface 42 may include an interference fit between the hollow body 40 and the collection medium support 60 to form the first seal 41. Alternatively, the first seal 41 may include other sealing means, such as a push fit or at least one O-ring seal.

[0067] The inlet 45 and the outlet 50 are fluidly coupled, which means that fluid (e.g., air) can flow into the particle sample collector 30 at the inlet 45 and then flow out of the particle sample collector 30 at the outlet 50.

[0068] As will be explained in more detail below, an air flow (air stream) through the particle sample collector 30 from the inlet 45 to the outlet 50 can be generated by providing a vacuum source 90 at the outlet 50.

[0069] A second interface 52 may be provided between the outlet 50 of the particle sample collector 30 and the vacuum source 90. A second seal 51 may be provided at the second interface 52.

[0070] The second seal 51 may be similar in structure to the first seal 41. For example, the second seal 51 may include at least one O-ring seal.

[0071] The vacuum source 90 used can be any suitable vacuum source. For example, the vacuum source 90 can be provided by a conventional household or industrial vacuum cleaner.

[0072] The outlet 50 may have an inner diameter corresponding to the diameter of the inlet line of the vacuum cleaner, e.g., about 32 mm.

[0073] The vacuum cleaner can be powered by an internal battery, making it portable and easily transportable to the location where the sample is to be collected. This can be advantageous if a gas turbine engine is assembled and installed on an aircraft and on-site sample collection is required.

[0074] The collection medium support 60 is configured to support the collection medium 70. In use, the particle sample 81 is collected on or within the collection medium 70.

[0075] In Figure 2In an example, the collection medium support 60 can be joined to the hollow body 40 and can slide relative to the hollow body 40 such that when it is joined to the hollow body 40, the collection medium 70 is supported by the collection medium support and is located between the inlet 45 and the outlet 50.

[0076] In some embodiments, for example, as Figure 2 shown, the collection medium can be held between the facing surfaces of the collection medium support and the hollow body. For example, the collection medium can be sandwiched at its periphery between a portion of the collection medium support 60 and the hollow body 40.

[0077] In other embodiments, fixing features (not shown) can be provided on the collection medium support 60 to hold the collection medium 70 in place. Examples of such fixing features include at least one recess projecting from the surface of the collection medium support 60 into which a peripheral portion of the collection medium 70 can be inserted.

[0078] Since the collection medium support 60 can move (e.g., slide) relative to the hollow body 40, the collection medium support 60 can be separated from the hollow body 40 such that the support surface 61 of the collection medium support can be accessed to allow the collection medium 70 to be placed on the support surface 61 of the collection medium support and then the support 60 and the hollow body 40 can be reassembled.

[0079] Different forms of the support surface 61 can be envisioned.

[0080] For example, in some embodiments, the support surface occupies the cross-section of the collection medium such that it extends through the void within the hollow body 40, thereby separating the inlet 45 and the outlet 50.

[0081] In these embodiments, since the inlet 45 and the outlet 50 are fluidly connected, the support surface 61 of the collection medium support 60 is porous or perforated such that fluid can flow through the support surface as it flows from the inlet 45 to the outlet 50. An example of such a form of the support surface 61 including a plurality of through-holes 62 is shown in Figure 3, which shows how the support surface 61 is perforated. Any suitable pattern of through-holes 62 can be used.

[0082] Other orientations of the support surface 61 (not shown) can also be envisioned.

[0083] For example, the support surface 61 and thus the collection medium 70 disposed on the support surface 61 can be inclined at an angle to the fluid flow within the collector 30 or can even be aligned with the fluid flow from the inlet 45 to the outlet 50.

[0084] Aligning the collection medium with the flow direction can be advantageous as it allows the collection medium to extend along the direction of the fluid flow. This means that the area of the collection medium can be increased without proportionally increasing the cross-sectional area of the particulate sample collector 30.

[0085] Similarly, in some embodiments, the support surface 61 may not be planar, but may have a corrugated or crenellated profile (i.e., a non-planar surface profile). Accordingly, the collection medium disposed on the non-planar support surface may also adopt a similar profile. This allows the surface area of the collection medium 70 to be increased without proportionally increasing the cross-sectional area of the particulate sample collector 30.

[0086] In cases where a compact collector 30 is desired, various ways of increasing the surface area of the collection medium 70 without proportionally increasing the cross-sectional area of the sample collector are advantageous. For example, in cases where the collector has to pass through a duct mirror port in the engine housing to sample from the surface of engine components within an assembled engine, or in cases where the geometry of the components makes a smaller diameter collector preferable.

[0087] The collection medium can be made of any suitable material. For example, the collection medium can include cellulose (e.g., as paper), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polypropylene, quartz, or polyamide (e.g., nylon).

[0088] The collection medium is porous to allow the airflow 80 to pass through it. The collection medium has a pore size suitable for collecting the particulate sample 81 required for analysis.

[0089] To ensure an appropriate sample volume is captured while maintaining sufficient airflow at the inlet 45, the collection medium 70 can have a pore size less than 2 microns. Preferably, the collection medium 70 has a pore size of approximately 0.2 microns.

[0090] In this way, the collection medium 70 can collect particles having a characteristic particle size greater than the pore size of the collection medium 70.

[0091] It will be appreciated that different engine components may be more or less sensitive to wear than other components. Accordingly, different collection media having different pore sizes can be selected when sampling different components of a gas turbine engine.

[0092] Alternatively or additionally, the collection medium may include a plurality of different layers, the different layers having different pore sizes. The different layers may be separated from each other such that particles having different characteristic grain sizes collected on different layers may be extracted from the collection medium for analysis. If the collection medium includes different pore sizes, the pore size of successive layers may decrease as particulate matter passes through the medium, i.e., the upstream layer has a larger pore size than the downstream layer. This may be beneficial because, during collection of a particulate sample, such an arrangement of layers subdivides the particulate matter into different size ranges.

[0093] Further improvements are also contemplated.

[0094] For example, although the movable nature of the hollow body 40 relative to the collection medium support provides a simple way to replace the collection medium 70, it may be desirable to form a first seal 41 between the hollow body 40 and the collection medium support 60 at the first interface 42.

[0095] The first seal 41 may be partial because some leakage past the first seal is acceptable, for example, if the resulting gap between adjacent surfaces permits movement between the hollow body and the collection medium support.

[0096] It may be desirable to form at least a partial seal at the first interface 42 between the hollow body 40 and the collection medium support 60 because this reduces the total effective area (sum of the leakage area and the inlet area) through which air and particulate matter are drawn into the particle sample collector 30, and in the limit ensures that air and particles are drawn into the particle sample collector 30 only via the inlet 45.

[0097] For a given strength of the vacuum source, this increases the velocity of the air entering the inlet 45 and thus increases the suction strength available to entrain solid particles accumulated on the surface of the gas turbine components.

[0098] This is particularly advantageous in situations where the particulate matter accumulation is relatively low and / or the particulate matter adheres to the surface of the gas turbine components and / or the topology of the surface of the gas turbine components including the particles to be sampled is such that the inlet 45 may not be placed close to the surface.

[0099] Various ways of forming at least a partial first seal 41 may be contemplated, either alone or in combination, as the case may be.

[0100] For example, the facing surfaces of the hollow body 40 and the collection medium support 60 may be an interference fit. However, this may have the disadvantage that it impedes movement between the hollow body 40 and the collection medium support 60 and thus impedes the convenience of replacing the collection medium 70.

[0101] Alternatively, the facing surfaces of the hollow body 40 and the collection medium support 60 may be a push fit.

[0102] Alternatively, the collection medium 70 may have an external feature size that is greater than the internal size of the collection medium support and / or the hollow body. In this way, the peripheral portion of the collection medium can be held (clamped) between the collection medium support 60 and the hollow body 40 (see Figure 2 ). A compressive force for holding the collection medium in place can be generated by providing a vacuum source to the outlet 50, since the resulting reduction in air pressure within the hollow body 40 causes the axially facing surfaces of the hollow body 40 and the collection medium support 60 to be pressed together.

[0103] Alternatively or additionally, the hollow body 40 may include an external thread aligned along the main axis 35, and the collection medium support 60 may include a corresponding internal thread aligned along the same axis, or vice versa. Tightening the external thread relative to the internal thread allows the hollow body 40 and the collection medium support 60 to be held together to form the first seal 41.

[0104] Alternatively or additionally, an elastomeric seal may also be provided between the radially facing surfaces of the hollow body and the collection medium support 60 to form the first seal 41. This is shown in Figure 3a where a first groove 63 is provided in the facing surface of the collection medium support 60 located at the first interface 42, the first groove positioning an elastomeric O-ring seal (not shown). Although in Figure 3a the first groove 63 is located in the facing surface of the collection medium support, it will be readily appreciated that the first groove 63 may alternatively be located in the facing surface of the hollow body.

[0105] Figure 3a Also shown is a second groove 64 that may be provided at the second interface 52 between the outlet 50 of the particulate sample collector 30 and the vacuum source. The second groove 64 houses an elastomeric O-ring seal (not shown), which forms the second seal 51 and reduces leakage at the second interface 52.

[0106] Alternatively, the second interface 52 may include an interference fit, a push fit, a thread, etc., to form these second seals in a manner similar to the formation of the previously disclosed first seal.

[0107] The air velocity at the inlet of the collector 30 can also be increased by reducing the cross-sectional area of the inlet 45 relative to the cross-sectional area of the outlet 50, where the outlet 50 is docked with the vacuum source. Thus, the particulate sample collector 30 can be connected to the vacuum source via the outlet 50.

[0108] When a suitable vacuum source is provided at the outlet 50, the air velocity at the inlet 45 can be at least 0.1 m / s.

[0109] Preferably, the air velocity at the inlet 45 can be at least 0.8 m / s.

[0110] Optionally, the tip of the nozzle 44 (if present) can be hardened relative to the other parts of the hollow body 40, or can include an outer coating or sheath to provide such hardening. The outer coating and / or sheath do not impede the entry of the airflow including the particulate matter 81 into the inlet 45.

[0111] If the tip of the nozzle is hardened, the tip of the nozzle can be used to scrape the particulate matter from the surface of the gas turbine engine component, so that the particulate matter can be entrained by the airflow 80 entering the inlet 45 as a particulate sample 81. The tip of the nozzle can be described as a scraping surface.

[0112] Optionally, the tip of the nozzle can be shaped. For example, the tip of the nozzle can be inclined at an angle with respect to the main axis 35 of the collector.

[0113] For example, the tip of the nozzle can be inclined at an angle of 30° to 60° with respect to the main axis 35.

[0114] Preferably, the tip of the nozzle can be inclined at an angle of about 45° with respect to the main axis 35. In this context, "about" can be interpreted as + / - 5°.

[0115] Inclining the tip of the nozzle may be desirable because it allows the nozzle 41 to be used as a scraper to remove particulate matter for sampling, while ensuring that an appropriate air flow velocity is maintained to collect the sample.

[0116] Alternatively, in some cases, it may not be desirable to use the tip of the nozzle 44 of the hollow body as a scraper, but instead use an alternative component for this purpose.

[0117] Figure 4 Illustrated is how the tube 85 can be connected (attachable) and connected to the inlet 45 in these cases.

[0118] The tube 85 is hollow.

[0119] The tube can have a substantially constant cross-sectional area along its length between its first end 85a and its second end 85b.

[0120] The tube 85 extends the scope of the collector 30 because it enables suction to be applied to the gas turbine engine component, which could not otherwise be achieved solely by the collector inlet 45.

[0121] The tube 85 has a first end 85a and a second end 85b opposite the first end 85a.

[0122] The tube 85b can be connected to the inlet 45 at its first end 85a.

[0123] The second end 85b of the tube 85 is for obtaining a particulate sample 81 from the surface of a gas turbine engine. The second end 85b of the tube 85 may include a second nozzle 86 or may be capable of being connected to the second nozzle 86.

[0124] The second nozzle 86 has a cross-sectional area smaller than that of the tube 85. This can be beneficial because, for a given vacuum source 90, it increases the air flow velocity and thus the entrainment of the particulate sample relative to the case where the second nozzle 86 is absent.

[0125] The second nozzle 86 may have similar characteristics to the first nozzle, i.e., the second nozzle may include a scraping surface; the tip of the second nozzle may be inclined at an angle 86a (e.g., between 30° and 60°) with respect to the main axis of the second nozzle 86 or the second end 85b of the tube 85; the air flow velocity at the inlet of the second nozzle may be at least 0.1 m / s, etc.

[0126] The tube can be rigid or flexible.

[0127] The length of the tube, the outer diameter of the tube, and / or the stiffness of the tube can be selected based on the position and local topology of the part of the gas turbine engine component from which the particulate sample 81 is to be collected, as the position and local topology determine the ease of access for obtaining the particulate sample.

[0128] In the case where there is a line of sight between the collector 30 and the part of the gas turbine engine component from which the particulate sample 81 is to be obtained, a rigid tube 85 may be required because a rigid tube can transmit the force applied by the user. For example, the rigid tube 85 can effect scraping of the particulate matter from the surface of the gas turbine engine component.

[0129] If the sample is to be obtained by endoscope inspection of the assembled engine, it may be desirable to use a flexible tube 85. The flexible hollow extension can be configured to be attached to an endoscope or can form part of an endoscope. In this way, the user can observe the surface of the gas turbine engine component and the accumulated particles while obtaining a sample of the particles.

[0130] The combination of the particulate sample collector 30 and the tube 85 (which can be attached to an endoscope or a tube included within an endoscope) forms a system 130 for collecting particulate samples.

[0131] Optionally, the system may also include a second nozzle (as Figure 4 shown) to improve the collection of particulate samples.

[0132] The collector 30 can optionally be formed by an additive manufacturing process such as stereolithography.

[0133] This may be desirable because in some cases, there may be a need to collect particulate samples in a short period of time, and the collector 30 may not be available. This situation may occur when the engineering team of an airline receives an aircraft for routine maintenance and discovers deposits on the surface of a gas turbine engine component as part of the maintenance inspection of the team's routine maintenance check.

[0134] The above optional features can be applied individually or in combination with Figure 2 the collector 30 shown in Figure 4 or the system 130 shown in

[0135] The above optional features can also be applied individually or in combination with different example structures of the collector 30 or the system 130, which also falls within the scope of the present invention.

[0136] Figure 5a and 5b show examples of different structures of the collector 30. Such different structures of the collector 30 can also form part of the system 130.

[0137] Similar to Figure 2 and 3a 3b, Figure 5a and 5b the particulate sample collector 30 includes a hollow body 40 having an inlet 45.

[0138] Similar to Figure 2 the particulate sample collector 30 also includes an outlet 50 fluidly coupled to the inlet 45, wherein a collection medium 70 is supported on a support surface 61 of a collection medium support 60 between the inlet 45 and the outlet 50. Similar to Figure 2 in

[0139] the collection medium support 60 can move (slide) relative to the hollow body 40 and can engage with the hollow body 40. Figure 2 Similar to the example in

[0140] However, different from Figure 2 the collection medium support 60 does not slide (move) along the main axis 35 of the collector (and the hollow body 40), but slides at an angle relative to the main axis 35. In the example of Figure 4 the collection medium support 60 slides at an angle substantially orthogonal to the main axis 35.

[0141] Therefore, in Figure 5a and 5bIn the example, the collection medium 70 is side-loaded into the particle sample collector 30 in a manner similar to loading a photographic slide into a slide projector. Thus, Figure 5a and 5b the collection medium support 60 of 5b is not substantially three-dimensional and may be substantially two-dimensional (planar) since it supports a substantially planar collection medium 70.

[0142] It will be appreciated that the collection medium support 60 may also include fixing features (not shown) to fix the collection medium 70 when it is loaded into the collector 30.

[0143] Figure 5a and 5b Other differences between the example of and the example of Figure 2 also fall within the scope of the present invention, including: in and 5b , the outlet 50 is not included within the particle sample collector 60 but instead is included within the hollow body 40, and the inlet 45 is not included within the continuously expanding nozzle 41, but there is a step change in cross-sectional area between the inlet 45 and the cross-sectional area of the hollow body 40. Figure 2 the example of and Figure 5a and 5b in 5b , the outlet 50 is not included within the particle sample collector 60 but instead is included within the hollow body 40, and the inlet 45 is not included within the continuously expanding nozzle 41, but there is a step change in cross-sectional area between the inlet 45 and the cross-sectional area of the hollow body 40.

[0144] Thus, Figure 5a and 5b the second example collector 30 in Figure 5a and 5b shows an alternative structural arrangement to achieve substantially the same functional performance as the first example in Figure 2 . Figure 2 the first example in Figure 2 .

[0145] Other example structures can be readily designed that also fall within the scope of the present disclosure. For example, although the above disclosure relates to a user-detachable collector to enable replacement of the collection medium 70, the collector 30 may also be provided as a non-user-maintainable item (i.e., as a cartridge) where the collection medium 70 is removed only immediately prior to analyzing the sample. It will be appreciated that in this example, it may be desirable for the first interface 42 between the hollow body 40 and the collection medium support 60 to be an interference fit since this facilitates assembly of the cartridge.

[0146] Figure 6 A method 100 for determining the composition (physical and / or chemical composition) of particulate residues on the surface of a gas turbine engine component is shown. As previously described, it uses the collector 30 or the system 130 to obtain a particulate sample.

[0147] The method 100 includes two steps 101 and 102 and an optional third step 103. The first step 101 involves obtaining a particulate sample 81 from the surface of the gas turbine engine component via suction. The second step 102 involves analyzing the particulate sample 81. The optional third step 103 involves determining the suitability of the material forming the surface of the gas turbine engine component based on the analysis of the particulate sample.

[0148] In step 101, a vacuum source 90, such as a conventional vacuum cleaner, is attached to the outlet 50 of the particulate sample collector 30.

[0149] The airflow 80 generated by setting the vacuum source entrains the particulate sample 81, sucking the particulate sample 81 through the particulate sample collector 30 such that the particulate sample 81 is collected by the collection medium 70, and the airflow 80 exits the particulate sample collector 30 at the outlet 50.

[0150] It will be appreciated that in some cases, depending on the characteristic aperture of the collection medium 70 and the range of characteristic particle sizes entrained in the airflow 80, the airflow 80 leaving the outlet 50 may still include particulate matter with a characteristic particle size smaller than the characteristic aperture of the collection medium, as this material may pass through the collection medium 70.

[0151] Although finer particle sizes can be collected by replacing the collection medium 70 with a medium having a smaller characteristic aperture, this may have the disadvantage that as the amount of particulate sample collected becomes smaller, the collection medium is prone to clogging (blocking).

[0152] Accordingly, the collection medium 70 can be selected at least in part based on its characteristic aperture such that the particulate sample 81 collected by the collection medium contains particles of the size required for subsequent analysis while ensuring that a suitable mass of particulate sample is collected to enable such analysis.

[0153] The particulate sample 81 is collected on the surface of the collection medium or within at least one pore of the collection medium 70. Since the characteristic size of the particles included in the particulate sample 81 is greater than the characteristic aperture of the collection medium 70, the particulate sample 81 is collected.

[0154] To ensure that a sufficient sample volume is captured, assuming the vacuum source is provided by a standard 32 mm outside diameter UK vacuum cleaner hose, the vacuum source has a flow rate of at least 35 liters per minute.

[0155] To ensure that a sufficient sample volume is captured, the velocity of the airflow 80 at the inlet 45 is at least 0.1 m / s and preferably 0.8 m / s.

[0156] After collecting the sample, the collection medium 70 now including the sample 81 can be removed from the collector 30 and stored. If desired, the collector 30 can be cleaned before being used to collect another sample.

[0157] Alternatively, a single sample can be collected using a single collector, where sealing means (such as a plug or dust cap) are provided at the inlet 45 and the outlet 50 to seal the collector 30 before storage and subsequent analysis.

[0158] The analysis of the particulate sample stored on or in the collection medium is performed in step 102.

[0159] Example analysis techniques include X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) analysis, energy-dispersive X-ray (EDX) analysis, wet chemical analysis, particle size distribution (PSD) analysis, inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), electron probe, isotope analysis, and differential scanning calorimetry (DSC). Differential scanning calorimetry may include rapid differential scanning calorimetry.

[0160] The above analysis techniques determine the physical and chemical composition of the particulate sample.

[0161] Over time and by repeatedly performing method steps 101 and 102 on samples from multiple engines, a mapping of how particulate matter accumulates on the surface areas of components of a gas turbine engine is formed. This mapping may have at least one of the following characteristics: · The typical particle size ranges and locations within the gas turbine engine; · The relative accumulation rates of particles within different parts of the gas turbine engine; · The changes in the physical and / or chemical properties of particles within different parts of the gas turbine engine; · The effectiveness of other engine health deterioration mitigation methods (such as engine core cleaning) based on changes in samples obtained before and after core cleaning; and · Changes in any of the above depending on the typical operation and / or geographical location of the aircraft including the sampled gas turbine engine.

[0162] Optionally, in step 103, the above information may be analyzed to determine the suitability of the material forming the surface of the gas turbine engine component from which the particulate sample was taken.

[0163] In these instances, the surface of the gas turbine engine component may or may not have a coating.

[0164] If the gas turbine engine component does not have a coating, the material forming the surface of the gas turbine engine component is the material of the body of the manufactured gas turbine engine component. For example, if the gas turbine engine component is a turbine blade, the material is a turbine blade alloy, such as an alloy including nickel.

[0165] If the gas turbine engine component has a coating, the material forming the surface of the gas turbine engine component is the applied coating (surface coating). For example, the material may be a thermal barrier coating or an environmental barrier coating.

[0166] Here, determining the suitability of the material of a gas turbine engine component may include determining whether an existing surface coating on a portion of the gas turbine engine component where particles accumulate can provide sufficient protection against the type of particles that have accumulated, e.g., against chemical or physical attack such as erosion, or whether the material should be replaced with a different material.

[0167] Determining suitability may include determining whether the area where the coating has been applied can be optimized, e.g., increasing the area to be surface-coated if accumulation is found to be more severe than expected, or decreasing the area to be surface-coated if accumulation is found to be less severe than expected, or the damage is less than expected.

[0168] Optionally, based on the above mapping of how particulate matter accumulates on the surfaces of components of a gas turbine engine, different coatings may be selected for different components or different parts of these components.

[0169] Steps 101, 102, and optional step 103 may be combined with the flight record analysis of the gas turbine engine 10 from which at least one particle sample can be obtained.

[0170] The flight record of the gas turbine engine 10 may include information on the flight routes flown by the aircraft equipped with the gas turbine engine 10, the power settings (e.g., takeoff thrust) used during the operation of these routes, and / or the number of flights since the last particle sampling.

[0171] In this way, over time, the operator or manufacturer of the gas turbine engine 10 can determine the rate at which particulate matter can accumulate on the components of the gas turbine engine and / or the physical and / or chemical composition of the particulate matter depending on the flight route and / or the power settings used on that route.

[0172] This information may be useful to the manufacturer as it enables the manufacturer to apply coatings optimized for the specific environment in which the engine will be used to subsequent gas turbine engine components. For example, a gas turbine engine manufacturer may apply different coatings to gas turbine engine components used in gas turbine engines designated to be used in hot and dusty conditions compared to other operating areas.

[0173] This information can also enable the manufacturer to modify the gas turbine engine components such that they are optimized for the specific environment in which the engine will be used.

[0174] For example, if after flying certain routes, the analysis determines that the characteristic particle size of the collected particle samples may have a harmful effect on the gas turbine engine components, the gas turbine engine components can be redesigned in view of this.

[0175] For example, it may be determined that when flying on certain flight routes, design features such as passages within a component are more prone to blockage because the component is exposed to particulate matter that is larger than normally expected. In such cases, the diameter of the passage can be increased as a design mitigation for subsequent components.

[0176] For example, the diameter of the cooling holes in a new or modified turbine blade design can be determined in part based on the determination of the characteristic diameter of the particulate matter to which existing turbine blades are exposed in use. In some cases, the diameter of the cooling holes in the turbine blades installed on a gas turbine engine operating on certain flight routes where larger diameter particulate matter may be encountered may be increased.

[0177] It will be understood that the present invention is not limited to the above embodiments, and various modifications and improvements can be made without departing from the concepts described herein. Unless mutually exclusive, any feature can be used alone or in combination with any other feature, and the present disclosure extends to and includes all combinations and sub - combinations of one or more of the features described herein.

Claims

1. A particle sample collector for collecting particle samples deposited on a surface of a gas turbine engine component, the particle sample collector comprising: a collection medium support comprising a support surface that supports a collection medium between an inlet of the particle sample collector and an outlet of the particle sample collector; wherein: The inlet is included within the hollow body; The inlet and the outlet are fluidly coupled; and The outlet is included within the hollow body, or The outlet is included in the collection medium support; in: The airflow carrying the particle sample enters the particle sample collector at the inlet; The collecting medium collects the particle sample; The airflow exits the particle sample collector at the outlet; and The outlet of the particle sample collector may be connected to a vacuum source that creates at least a partial vacuum within the hollow body, causing the airflow and the particle sample carried by the airflow to enter the particle sample collector via the inlet.

2. The particle sample collector of claim 1, wherein the support surface is porous or perforated.

3. The particle sample collector of claim 1, wherein the collection medium is configured to collect particles having a characteristic particle size greater than 0.2 microns.

4. The particle sample collector according to any one of claims 1 to 3, wherein the hollow body comprises a nozzle, the inlet is located at the tip of the nozzle, and the tip of the nozzle is inclined at a certain angle to the main axis of the particle sample collector, and / or the tip of the nozzle comprises a scraper surface.

5. The particle sample collector of claim 1, wherein the inlet is configured to be connected to a first end of a tube, and the tube has a second end having a second nozzle or configured to be connected to a second nozzle. 6 . The particle sample collector according to claim 5 , wherein the second nozzle has a scraper surface at its tip and / or the tip of the second nozzle is inclined at a certain angle relative to the main axis of the second nozzle. The particle sample collector of claim 5 , wherein the tube is a flexible tube.

8. The particle sample collector of claim 5, wherein the tube is part of a borescope or the tube is connectable to a borescope.

9. A method of determining the composition of particulate residue on a surface of a gas turbine engine component, the method comprising: obtaining a particle sample from a surface of said gas turbine engine component using a particle sample collector according to any preceding claim; Analyzing the particle sample to determine the composition of the particle residue, wherein analyzing the particle sample comprises at least one of: X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) analysis, energy dispersive X-ray (EDX) analysis, wet chemical analysis, particle size distribution (PSD) analysis, inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), electron probe, isotope analysis and / or differential scanning calorimetry (DSC); and The suitability of a material for forming a surface of a gas turbine engine component is determined based on the analysis of the particle sample.

10. A system for collecting a sample of particles deposited on a surface of a gas turbine engine component, the system comprising: The particle sample collector according to any one of claims 1 to 8; Tube; as well as a vacuum source connected to an outlet of the particle sample collector; wherein the tube is connected at a first end thereof to an inlet of the particle sample collector and obtains a particle sample at a second end thereof due to the action of the vacuum source; and Wherein the tube may be attached to a borescope, or the tube may be comprised within the borescope.

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