Method for checking a component for a turbomachine

Abstract

The present invention relates to a method for checking a component (45) for a turbomachine (1), in particular an aircraft engine (5), comprising the following steps: i) providing (81) a plenoptic camera system (30) which has a plurality of sensor regions (33) for detecting light beams incident from different directions; ii) capturing (82) an image (35) of the component (45) by means of the plenoptic camera system (30); iii) determining (83) a suitability of the component (45) for use in the turbomachine (1) based on the captured image (35).

Description

[0001] METHOD FOR TESTING A COMPONENT FOR A TURBOMACHINE

[0002] DESCRIPTION

[0003] Technical area

[0004] The present invention relates to a method for testing a component for a turbomachine, in particular an aircraft engine.

[0005] State of the art

[0006] Functionally, a turbomachine can be divided into a compressor, a combustion chamber, and a turbine. For example, in a jet engine, the intake air is compressed in the compressor and burned in the downstream combustion chamber with kerosene mixed in. The resulting hot gas is expanded in the downstream turbine, where energy is extracted from the hot gas to drive the compressor and, depending on the design, a fan, for example.

[0007] Due to the potential consequences of component failure, their quality and testing may generally require special attention. However, even independent of a potential total failure, damage to components can be detrimental due to potential efficiency losses. This can affect, for example, run-in linings or seals, where material or processing defects can result in leaks and thus adversely affect efficiency.

[0008] Description of the invention

[0009] The present invention is based on the technical problem of specifying an advantageous method for testing a component and a corresponding device. This is achieved by the method according to claim 1 and the device according to claim 7. A plenoptic camera system is provided which has a plurality of sensor areas with which incident light from different directions can be detected. Accordingly, the component is simultaneously detected by the camera system from different directions, so the recorded image also contains directional information. This allows, for example, a 3D image or depth profile to be obtained, as explained in detail below, which can reveal deviations from a desired shape, for example.

[0010] This is used in an evaluation step to determine the component's suitability for use in the turbomachine (step iii) based on the image acquired in step ii). Due to the additional angular information obtained with the plenoptic camera system, i.e., the expanded data space compared to a 2D image, for example, step iii) is particularly amenable to automation; the larger data space can help reduce any misclassifications.

[0011] Preferred embodiments can be found throughout the disclosure and in particular in the dependent claims, whereby the presentation of the features does not always distinguish in detail between method, use, or device aspects; in any case, the disclosure is implicitly to be read with regard to all claim categories. For example, if the device suitable for a specific measurement is explained in more detail, this is to be read simultaneously as a disclosure of a corresponding method, and vice versa.

[0012] With regard to the aforementioned automation, the method steps ii) and / or iii) can preferably be computer-implemented. For example, a control unit can initiate the recording of the image (step ii)) and / or an evaluation unit can determine the suitability of the component based on the image (step iii)), see details below. In a preferred embodiment, the tested component is a run-in lining, in particular a so-called honeycomb seal. This can be constructed, for example, from interconnected sheet metal strips, with the sheet metal walls or, in general terms, cell walls forming a cellular structure. These cells can, for example, be arranged on a so-called seal carrier and form cavities open in a radial direction away from the seal carrier, for example, in the case of a run-in lining assigned to the blade tips, in particular sealing fins, of a rotor, cavities open radially inwards.Viewed from above, i.e. in the example from just above looking radially outwards, the cells can, for example, have a hexagonal basic shape (“honeycomb seal”), but this is generally just as unimportant as the manufacture from sheet metal strips.

[0013] This method can also be used to inspect abradable linings or seals with other cell shapes (e.g., oblique, rectangular, or free-form), which can be manufactured, for example, using a 3D printing process. Regardless of these details, the application of this method to an abradable lining with a system or grid of cells can be advantageous, for example, in that the cell walls have a certain height or the cells have a corresponding depth, which is why the additional depth information obtained with the plenoptic camera system can be advantageous.

[0014] For example, material deposits, such as solder, can be detected at the base of the cell or in the cell (“filled cell”), or damage to the cell wall can be detected. This could be, for example, a crack originating at the edge of the cell wall or a hole lying flat in the cell wall. If the cell walls of the abradable lining are joined using solder, for example to one another and / or to a seal carrier, solder splashes or cracks in the solder can also be detected. It can also be taken into account whether a cell is open to the seal carrier, i.e. not or at least not completely connected to it. Furthermore, the directional information obtained can be used to detect deformation of cell walls, for example. Especially in a cell structure composed of individual parts, e.g. sheet metal strips, open nodes (unconnected cell walls) or overlaps in joint areas (overlap of horizontal and / or diagonal joints) can also be inspected.The inspection can focus on newly manufactured seals, but in the course of an overhaul it can also focus on wear tests on components that have already been used.

[0015] According to a preferred embodiment, the run-in coating is additionally illuminated with a light source, such as a diode, a fiber optic cable, or laser light. This can, as explained in more detail below, be done during image acquisition with the plenoptic camera system. This can, for example, increase reproducibility, which can be advantageous with regard to the relative comparability of different measurements (e.g., on different components). By tilting the light incidence, different areas could also be illuminated / highlighted, for example; alternatively or additionally, the color spectrum can also be varied (blue, red component, etc.).

[0016] Additionally or alternatively, the illumination can also be used, for example, to cause lateral or general scattered light to escape from defective cells. This can preferably be measured using an additional optical sensor, such as a photodiode. The optical sensor can be arranged laterally next to the inlet coating or the cell structure, e.g. directed from the side onto its cell walls. This can be used to verify the evaluation with the plenoptic camera system or to make difficult-to-detect defect images accessible, e.g. slight lifting at the lower end of the cell walls (on the seal carrier). This variant "illumination with a light source and detection with an optical sensor" is also intended to be disclosed independently of the measurement using the plenoptic camera system, and can therefore also be used on its own for the automated determination of component suitability.

[0017] In general, the image taken of the component can also be used directly to determine component suitability in step iii). In a preferred embodiment, a processed image is used alternatively or additionally. For example, the plenoptic camera system can capture a 2D image and a depth image of the component, from which a 3D image and / or a depth profile can be generated. The latter can be of interest, for example, with regard to defect patterns such as "filled cell" or "solder splashes." The 3D image can reveal, among other things, cracks, openings, and holes.

[0018] Preferably, the camera system and the component are moved relative to each other, meaning the component moves through the camera system's detection field (for example, in a fixed coordinate system, either the component or the camera system is moved). This allows for a large number of images to be captured, each of which can be evaluated individually or combined to form an overall image.

[0019] In general, the “plenoptic camera system” can, for example, also be constructed from several separate sensor units, each of which can capture the component from a different direction using its own optics when taking the image. In a preferred embodiment, however, the camera system is provided in the form of a light field camera in which the sensor areas are structurally integrated, i.e., e.g., housed together. The sensor areas can, in particular, be different areas of a common image sensor (e.g., a CMOS sensor). The optics of the light field camera can have a so-called microlens array, which includes a large number of microlenses through which light is passed in parallel, wherein each sensor area is coupled to a respective spatial direction via a respective microlens. Independent of these details, one advantage of using a light field camera can, for example,This is because they are also commercially available in a relatively compact design, meaning they can be easily integrated into a measuring device.

[0020] The application further relates to a device for testing a component for a turbomachine, wherein the device, in addition to the plenoptic camera system, has a component holder for arranging the component and a guidance system. The guidance system allows the component holder and the plenoptic camera system to be moved relative to one another, meaning that a detection field of the camera system can be directed at different areas of the component holder and, accordingly, different areas of the component. This also allows larger components or component areas to be measured and thus tested, meaning the device is specifically designed for turbomachine components. Viewed in a stationary coordinate system, the component holder, and thus the component itself during measurement, can be moved; alternatively, the component holder remains stationary and the plenoptic camera system is moved with the guidance system.If this is intended as a light-field camera (see above), its compact design can be advantageous, for example. Regarding possible configurations of the testing device, reference is generally made to the rest of the disclosure; see the initial comments.

[0021] The guide system preferably has a rail that defines a movement path for the relative offset. In a preferred embodiment, the guide system defines a circular path, so, for example, the rail has a circular or circular arc shape. This means that the measuring device is specifically designed for the rotationally or rotationally symmetrical components of turbomachines, allowing, for example, their correspondingly curved surfaces to be reproducibly imaged.

[0022] Preferably, the rotational axis of the circular path and thus the device can coincide with a rotational axis of the component, around which the component is, for example, rotationally symmetrical. With respect to the turbomachine, this axis of the component can then preferably coincide with its longitudinal or rotational axis. Preferably, a circular or circular-arc-shaped rail is provided, in which the camera system, viewed in the stationary coordinate system, can be moved relative to the component holder, or conversely, the component holder can be moved.

[0023] In a preferred embodiment, the testing device or the guide system is designed to adjust different radii, so that, for example, a radius of the guide rail can be widened or narrowed, in other words, the guide rail is provided flexibly. Alternatively or additionally, a plurality of guide rails with different radii can be provided, which can be used interchangeably. The guide device can therefore be equipped with guide rails of different sizes, if required. According to a preferred embodiment, the device additionally has a mirror, wherein the plenoptic camera system is directed via the mirror onto the component holder. In other words, a detection field of the camera system is guided via the mirror onto the component holder, i.e., during measurement, onto the component arranged therein. The mirror, which is a separate element from the camera system, e.g.If the light field camera is located outside the housing, a "radial view" of the component can be simplified, even for smaller geometries. The detection field can be redirected multiple times using multiple mirrors or only once using a single mirror.

[0024] In a preferred embodiment, the mirror is arranged radially inside the component holder relative to a rotational axis of the circular path. This allows the detection field to be directed radially inward toward the component holder and the component. This allows, for example, the cell structure of a run-in coating with cells open radially inward to be inspected, which might otherwise be difficult to access. The mirror allows the camera system to be positioned outside a plane defined by the movement path, which can be advantageous in terms of space utilization.

[0025] According to a preferred embodiment, a tilting unit is provided with which the camera system and the component holder can also be tilted relatively. This tilting relates to a plane defined by the movement path, i.e. in which the movement path lies. In the preferred case of a circle or circular arc, this lies in the plane, i.e., the axis of rotation of the circular movement is perpendicular to it. With the relative tiltability, the detection field can be tilted, for example, relative to the radial direction, i.e., it can also be directed (slightly) laterally towards the cell walls. The tiltability is preferably combined with the mirror guidance, wherein the detection field is more preferably guided over the mirror in every tilt position accessible with the tilting unit.

[0026] As discussed above, in a preferred embodiment, the device comprises a light source, which can be used for scattered light measurement and / or for illumination during image acquisition with the plenoptic camera system. Preferably, the component holder and the light source are also movable relative to one another via the guide system, with the light source preferably remaining stationary relative to the camera system. In other words, the camera system and light source are jointly movable relative to the component holder, in particular tiltable.

[0027] Regardless of the specific suspension / mobility, a light source of the testing device is preferably configured to illuminate the detection area with different intensities and / or with light of different wavelengths. The latter can, for example, also mean a different spectral composition, i.e., a different intensity of different spectral components. In general, the reference to "light" does not necessarily mean a restriction to the visible spectral range; thus, UV and / or IR light can also be provided, for example (although at least components in the visible spectral range are preferred).

[0028] According to a preferred embodiment, the testing device comprises an evaluation unit which, based on the recorded image, automatically determines the suitability of the component for use in the turbomachine. In other words, the evaluation unit is configured to perform step iii); for further details, reference is made to the above explanations. Preferably, the device can also comprise a control unit which causes the plenoptic camera system to record the image, i.e., to perform step ii). The control and evaluation units can generally be provided as separate units (e.g., microcontrollers) or, alternatively, can be part of a common computer program.

[0029] The invention also relates to the use of a testing device for testing a component for a turbomachine, in particular a component for an aircraft engine. The component testing can be performed during new production, i.e., before initial installation, but also during an overhaul, i.e., when checking a component that has already been used. Brief description of the drawings

[0030] In the following, the invention is explained in more detail using exemplary embodiments, whereby no distinction is made in detail between the different claim categories.

[0031] In detail,

[0032] Figure 1 shows a turbomachine in an axial section to illustrate the application environment;

[0033] Figures 2a-h show schematic views of run-in coatings to illustrate possible defect patterns;

[0034] Figure 3 shows a schematic representation of a plenoptic camera system taking an image of a wall of an inlet coating;

[0035] Figure 4 shows a test device with a plenoptic camera system in a top view;

[0036] Figure 5 shows the test device according to Figure 4 in a side view;

[0037] Figure 6 shows a schematic representation of a measurement of a cell error using scattered light;

[0038] Figure 7 shows a flow chart with some process steps.

[0039] Preferred embodiment of the invention

[0040] To illustrate the application environment of the present test method, Figure 1 shows a turbomachine 1 in an axial section, i.e. viewed in a sectional plane containing its longitudinal axis 2. The turbomachine 1 shown is an aircraft engine 5, specifically a turbofan engine. Functionally, the turbomachine 1 is divided into a compressor 1a, a combustion chamber 1b, and a turbine 1c. Air drawn in the compressor 1a is compressed and then burned in the turbine 1b with added fuel, e.g., kerosene. The hot gas is expanded in the turbine 1c, which also drives its rotors 6. In the present case, some rotors 6 of the high-pressure turbine are referenced as examples; these transmit this rotational movement to rotors 7 of the compressor 1a, which applies analogously to the low-pressure turbine. Also referenced as examples are running-in linings 8, which surround the rotors 6 radially outwards and create a seal, e.g.together with sealing tips arranged on the blade tips or sealing fins of the rotors 6 (not shown in detail). The seals 8 or run-in linings are referenced here as examples; run-in linings can also be provided radially inside the stators, for example, to seal against the rotating shaft, i.e., in general terms, where parts are moving relative to one another, especially rotating.

[0041] Figures 2a-f illustrate, on the one hand, a common design of seals 8 and, on the other hand, typical fault or damage patterns. The run-in linings are provided in the form of cells 20, which are defined by cell walls 21 and are open in a radial direction relative to their installation position. In a typical design, the cell walls 21 form hexagonal cells 20, which is also referred to as a honeycomb seal. Figure 2a illustrates a crack 25 in the cell wall 21 as a possible damage pattern.

[0042] In Figure 2b, which shows the cells 20 in a radial plan view, a crack 27 can be seen in a solder 26, which serves to connect cells or cell walls 21. In Figure 2c, which again shows a radial plan view, the damage is located in an open node 28. Figures 2d / e illustrate cells 20 in a sectional side view, i.e., viewed in a sectional plane perpendicular to the plane of the drawing with reference to the orientation according to Figures 2b / c. In Figure 2d, the solder 26, which in this example serves to attach the cell to a seal carrier 29, has run into the cell 20, thus filling it up. In Figure 2e, however, the cell walls 21 are deformed. Figure 2f, again, shows a radial plan view, although in this case cell walls 21 that are actually adjacent in a butt joint incorrectly overlap.Figure 2g shows an oblique view of a hole 23 in a cell wall 21, and Figure 2h illustrates an open cell 21 with a perpendicular interruption 24 at the cell bottom. Figure 3 shows a plenoptic camera system 30, namely, in this example, a light field camera 31. This has a lens array 32 through which light rays incident from different directions are guided to different sensor areas 33. In this case, the sensor areas 33 are different areas of the same area sensor 34, e.g., a CMOS image sensor.

[0043] When capturing an image 35 with the plenoptic camera system 30, due to the aforementioned angular resolution, not only planar image information but also depth information is captured. Since the lens array 32 essentially provides a multitude of different views, the cell walls 21 can be captured without optical shading, i.e., figuratively speaking, from both sides. This allows the cell walls or cells to be examined, particularly for the defect patterns discussed above.

[0044] Figure 4 shows a device 40 for inspecting a component 45 of a turbomachine, which in this example is a segment of a seal 8. In addition to the light field camera 31, the device 40 has a component mount 41 and a guide system 42. The guide system 42 defines a circular path 43 along which the plenoptic camera system 30 and the component mount 41 are movable relative to one another over a circular arc 44.

[0045] The cells of the run-in coating 8 are open radially inward, i.e., toward a rotational axis 50 of the circular path 43. A detection field 56 of the plenoptic camera system 30 is deflected by a mirror 55, so that downstream of the mirror 55, the detection field 56 falls radially outward onto the component holder 41 or the component 45. The cells of the run-in coating can thus be captured, for example, in views comparable to Figures 2b, c, and f.

[0046] The device 40 further comprises a light source 60, with which the component 45 can be illuminated during image capture. The light 61 emitted by the light source 60 is also guided via the mirror 55. Figure 5 shows the device 40 in a schematic side view, i.e. rotated by 90° relative to the illustration in Figure 4, with a perpendicular view of the rotation axis 50. The component arranged in the component holder 41 cannot be seen here; the view is from the outside onto the guide system 44. By means of a tilting unit 65, the plenoptic camera system 30 can be tilted relative to a plane 66, so that, for example, it can be pivoted from a top view according to Figures 2b, c, f into an oblique view (similar to Figure 2a). The light source is pivoted together with the plenoptic camera system 30, although this is not shown for the sake of clarity.

[0047] Figure 6 illustrates a light source 60 whose light 61 falls into cells 20. An optical sensor 70 is arranged laterally next to the seal 8, which detects scattered light 61.1 emerging from the side. This allows the detection of a cell wall 21 that is not properly seated or soldered, i.e., a cell 20 that is defective at its lower end.

[0048] Figure 7 summarizes some of the method steps in a flowchart. After provision 81 of the plenoptic camera system, the component can be captured by capturing 82 the image 35. The subsequent determination 83 of the component's suitability for use in the turbomachine can be based on the image 35 and / or a 3D image 85 generated therefrom and / or a depth profile 86 generated therefrom.

[0049] LIST OF REFERENCE SYMBOLS

[0050] Turbomachine 1

[0051] Compressor la

[0052] Combustion chamber 1b

[0053] Turbine 1c

[0054] Longitudinal axis 2

[0055] Aircraft engine 5

[0056] Rotors 6, 7

[0057] Seals 8

[0058] Cells 20

[0059] Cell walls 21

[0060] Hole 23

[0061] Solder interruption 24

[0062] Crack 25, 27

[0063] Lot 26

[0064] Node 28

[0065] Seal carrier 29 plenoptic camera system 30

[0066] Light field camera 31

[0067] Lens array 32

[0068] Sensor areas 33

[0069] Area sensor 34.

[0070] Image 35

[0071] Device 40

[0072] Component holder 41

[0073] Guidance system 42

[0074] Circular Path 43

[0075] Circular arc 44

[0076] Component 45

[0077] Rotation axis 50 Mirror 55

[0078] Recording field 56

[0079] Light source 60

[0080] Light 61 Scattered light 61.1

[0081] Tilting unit 65

[0082] Level 66 optical sensor 70

[0083] Provide 81 Record 82

[0084] Determine 83

[0085] 3D image 85

[0086] Depth profile 86

Claims

CLAIMS 1. A method for testing a component (45) for a turbomachine (1), in particular an aircraft engine (5), comprising the steps of: i) providing (81) a plenoptic camera system (30) having a plurality of sensor regions (33) for detecting light rays incident from different directions; ii) recording (82) an image (35) of the component (45) with the plenoptic camera system (30); iii) determining (83) a suitability of the component (45) for use in the turbomachine (1) based on the recorded image (35).

2. Method according to claim 1, wherein the component (45) is a seal (8), in particular a honeycomb seal.

3. Method according to claim 2, in which a system of cells (20) of the abradable coating (8) is checked in step iii) for at least one of the following exclusion criteria: crack (25) in a cell wall (21), hole in a cell wall (21), crack (27) in a solder (26), solder splash, filled cell (20), deformed cell (20), open cell (20), open knot (28) between cell walls (21) and overlap at a joint between cell walls (21).

4. Method according to claim 2 or 3, in which the run-in coating (8) is additionally illuminated with a light source (60) and any scattered light (61.1) emerging laterally from a cell (20) of the run-in coating (8) is detected by an optical sensor (70) arranged adjacent thereto.

5. Method according to one of the preceding claims, wherein the determination (83) of the suitability in step iii) is carried out at least also on the basis of a 3D image (85) and / or depth profile (86) generated from the recorded image (35).

6. Method according to one of the preceding claims, wherein the plenoptic camera system (30) is a light field camera (31).

7. A device (40) for testing a component (45) for a turbomachine (1), in particular in a method according to one of the preceding claims, comprising: a component holder (41) for arranging the component (45); a plenoptic camera system (30) having a plurality of sensor regions (33) for detecting light rays incident from different directions; a guide system (43) by means of which the component holder (41) and the plenoptic camera system (30) are movable relative to one another.

8. Device (40) according to claim 7, wherein the guide system (43) defines a circular path (43) on which the component holder (41) and the plenoptic camera system (30) are movable relative to one another over at least one circular arc (44).

9. Device (40) according to claim 8, wherein the guide system (43) is arranged for setting different radii of the circular path (43).

10. Device (40) according to one of claims 7 to 9, which additionally has a mirror (55), wherein a detection field (56) of the plenoptic camera system (30) is directed via the mirror (55) onto the component holder (41).

11. Device (40) according to claim 10 in conjunction with claim 8 or 9, wherein the mirror (55) is arranged radially inside the component holder (41) with respect to an axis of rotation (50) of the circular path (43).

12. Device (40) according to one of claims 7 to 11 with a tilting unit (65), by means of which the plenoptic camera system (30) can be additionally tilted with respect to a plane (66) defined by the relative mobility in the guide system (43).

13. Device (40) according to one of claims 7 to 12, which additionally has a light source (60) for illuminating a detection field (56) of the plenoptic camera system (30), wherein the light source (60) is movable via the guide system (43) together with the plenoptic camera system (30) relative to the component holder (41).

14. Device (40) according to one of claims 7 to 13, which additionally has an evaluation unit which is designed to determine a suitability of the component (45) for use in the turbomachine (1) on the basis of an image (35) taken of a component (45) of a turbomachine (1) with the plenoptic camera system (30).

15. Use of a device (40) according to one of claims 7 to 14 for testing a component (45) for a turbomachine (1) during new production or revision, in particular in a method according to one of claims 1 to 6.

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