Inspection systems for gas turbine components and methods

Abstract

An inspection system (100) for a gas turbine component (131), wherein the gas turbine component (131) has at least one hole (101) having a free section, 5 wherein the inspection system comprises according to some components: a lighting device (103) configured to be located outside the gas turbine component (131) and to light the at least one hole (101); an optical camera device (102) configured to be located inside the gas turbine component (131) and to receive light from the lighting device (103) through the at least one hole (101); an 10 electronic processing unit (104) coupled at least to optical camera device (102) and configured to calculate an area of the free section of the at least one hole (101) based on an image captured by the optical camera device (102), whereby the gas turbine component (131) is interposed between the lighting device (103) and the optical camera device (102) and shelters the optical camera device (102) 15 from ambient light. According to alternative embodiments the positions of the lighting device and the optical camera device with respect to the gas turbine component can be exchanged.

Description

TITLEInspection Systems for Gas Turbine Components and Methods.DESCRIPTIONTECHNICAL FIELD

[0001] The subject matter disclosed herein relates to an assisted inspection system for gas turbine components more, in particular to assess an area of the free section of at least one opening in a gas turbine components. The subject matter disclosed herein relates also to a corresponding inspection method.BACKGROUND ART

[0002] In general, the objective of the combustor in a gas turbine is to add energy to the system to power the turbines and produce a high-velocity gas to exhaust through the nozzle in aircraft applications or to drive compressors in natural gas pipelines, to generate electricity in power plants, to propel ships or trains and to operate mechanical equipment such as pumps, compressors, and fans in industrial processes. The temperature profile within the combustor should avoid hot spots, as those can damage or destroy a combustor from the inside.

[0003] Cooling air is air that is injected through openings in the liner to protect the liner from the combustion temperatures, in particular to generating a layer or film of cool air. The airflow into the combustor may be controlled via louvers or slits in the inner dome, and by elongated slits along the length ofthe liner. These louvers are used as an opening, so that the air flow going through the slits can be used in the process of combustion and cooling.

[0004] It is known that film cooling is a typical technology that protects combustor liner from high temperature, further allows higher working temperature and extends combustor liner servicing life. In film cooling, coolant is discharged to the hot side of combustor liner through small openings in order to provide a thin cool insulating blanket along the surface of combustor liner. In this sort of cooling system, the shape of openings is a main factor affecting the effectiveness of film cooling.

[0005] It would be desirable to inspect each of the openings to determine whether it is properly formed, or obstructed o damaged by high temperature. One method of inspection is a manual method to assess and to calculate the area of the free section of an opening, with a go / no go gauge, in which an inspector is provided with a gauge and inserts the gauge through each of the openings to determine whether the opening is properly drilled and to assess the area and the profile of its free section.

[0006] As can be appreciated, such an inspection process is inefficient for the manufacturer of the gas turbine components, this method doesn’t return any data for analysis, and flow distribution.

[0007] Accordingly, it would be desirable to provide an inspection system that can automatically inspect openings, for example cooling openings, even if complex, in gas turbine components faster, more precisely also if the part under inspection is out of focus, than known devices and methods.

[0008] It would also be desirable to provide a method to determine an area of a free section of such openings.SUMMARY

[0009] According to a first aspect, the subject-matter disclosed herein relates to an innovative inspection system for a gas turbine component, wherein the gas turbine component has at least one hole having a free section, and the gas turbine component is interposed between the lighting device and the optical camera device and shelters the optical camera device from ambient light.

[0010] According to a second aspect, the subject-matter disclosed herein relates to an innovative inspection system for a gas turbine, comprises also a shelter device wherein the gas turbine component is interposed between the lighting device and the optical camera device, the shelter device outside the gas turbine component shelters the optical camera device from ambient light.

[0011] According to a third aspect, the subject-matter disclosed herein relates to an innovative method to determine an area of a free section of at least one hole in a wall of a gas turbine component.BRIEF DESCRIPTION OF THE DRAWINGS.

[0012] A more complete appreciation of the disclosed embodiments of the subject matter and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:Fig. 1 illustrates a schematic view of an embodiment of an inspection system of a gas turbine component;Fig. 2 illustrates an embodiment of a chamber combustion of gas turbine with a component of gas turbine to be inspected of Fig.1;Fig. 3 illustrates a schematic view of a second embodiment of theinspection system of a gas turbine component;Fig. 4 illustrates an embodiment of a chamber combustion of gas turbine with a component of gas turbine to be inspected of Fig.3;Fig.5 illustrates a schematic view of an alternative embodiment of the inspection system of a gas turbine component;Fig. 6 illustrates a schematic view of a second alternative embodiment of the inspection system of a gas turbine component;Figs. 7, 8, 9 illustrates a schematic view of alternative embodiments of a robotic device of the inspection system of a gas turbine component;Fig.10 illustrates a flow diagram of an embodiment of an innovative inspection method.DETAILED DESCRIPTION OF EMBODIMENTS

[0013] The inspection of at least one opening in a gas turbine, is essential for maintaining operational integrity, reliability, and safety of gas turbine. However, the inspection of the openings of a gas turbine components can present various challenges. Some common problems include: ensuring accurate inspection results for detecting any defects or irregularities that could affect the turbine's performance or safety; inspecting many holes in a timely manner can be time-consuming and labor-intensive, especially for turbines with numerous components, and reproducibility: enduring inspection results for maintaining quality control and identifying any trends or patterns in opening degradation over time.

[0014] According to the subject matter disclosed herein, an innovative inspection system for a gas turbine component comprises a lighting devicepositioned outside the turbine component to illuminate its holes. Inside the component, an optical camera device captures light from the lighting device passing through at least one hole. An electronic processing unit analyzes the captured images to calculate the area of the free section of the at least one hole. The turbine component acts as a barrier between the lighting device and the optical camera, shielding it from ambient light.

[0015] Furthermore, as disclosed herein an innovative inspection system for a gas turbine component comprises a lighting device positioned inside the turbine component to illuminate its holes. Outside the component, an optical camera device captures light from the lighting device passing through at least one holes. A shelter device configured to include inside the lighting device and the optical camera device, shielding them from ambient light. An electronic processing unit analyzes the captured images to calculate the area of the free section of the holes.

[0016] According to the subject matter disclosed herein, an innovative method to determine an area of a free section of at least one hole in a wall of a gas turbine component, this process involves positioning an optical camera and a lighting device with a wall between them to allow light from the lighting device to pass through at least one hole and reach the camera. The camera is shielded from ambient light, then it captures at least one image. Finally, the captured image is processed using an electronic unit to calculate the area of the free section of the hole by counting pixels with a brightness exceeding a predetermined threshold.

[0017] Referring now to drawings, Fig.1 and Fig. 3 show an innovative inspection systems 100 and 200 for gas turbine components suitable for carrying out an innovative method (see e.g. flow chart 500 in Fig. 9), toinspection at least one hole 101, 201 of a gas turbine component 131, 231, and to determine an area of a free section of the at least one hole of a gas turbine component.

[0018] The inspection system 100, 200 for a gas turbine component 131, 231, wherein the gas turbine component 131, 231 has the at least one hole 101, 201 having a free section, comprises: a lighting device 103, 203 configured to be located outside the gas turbine component 131, 231 and to light the at least one hole 101, 201; an optical camera device 102, 202 configured to be located inside the gas turbine component 131, 231 and to receive light from the lighting device 103, 203 through the at least one hole 101, 201; an electronic processing unit 104, 204 coupled at least to the optical camera device 102, 202 and configured to calculate an area of the free section of the at least one hole 101, 201 based on an image captured by the optical camera device 102, 202.

[0019] Preferably, the gas turbine component 131, 231 is interposed between the lighting device 103, 203 and the optical camera device 102, 202 and shelters the optical camera device 102, 202 from ambient light.

[0020] The said optical camera device 102, 202 comprises a telecentric lens, and preferably the lighting device 103, 203 is a LED light bar. The LED light bar with a wavelength value within a range of 480- 560 nm, preferably a range of 520 -530 nm.

[0021] Advantageously the said electronic processing unit 104, 204 is configured to calculate the area of the free section of the at least one hole 101, 202 by counting pixels of the at least one image.

[0022] Referring to Fig. 1, the system 100 may comprise a sliding unit 105 configured to be located inside the gas turbine component 131, wherein the sliding unit 105 extends from a first end to a second end of the gas turbine component 131. The sliding unit 105 preferably comprises: a rail 115 and a trolley 125 connected with the rail 115 through of a sliding coupling. Preferably the rail 115 extends from a first end to a second end of the gas turbine component 131.

[0023] The optical camera device 102 is configured to be located on the trolley 125 of the sliding unit 105, and to capture images of a plurality of holes 101 of the gas turbine component 131.

[0024] Referring to Fig. 2 the gas turbine component 131 of the system 100 is a combustion chamber liner of a tubular combustion chamber 130, preferably the tubular combustion chamber 130 is configured with the liner 131 and an outer case 132, outlining a space between liner 131 and outer case 132.

[0025] Preferably the at least one hole 101 of the combustion chamber liner is a louver, or rounded hole, or oval hole, or elliptical hole, or another similar. More particularly the at least one hole 101 is a fuel nozzle, or a cooling hole, or a bleed air port, or an exhaust nozzle, or an inlet guide vane opening, or a blade tip hole, or a pressure probe hole, or a oil drain hole, or a sealing air hole.

[0026] Referring to Fig.3 the system 200 comprises a linear element 240, configured to be located inside the gas turbine component 231, and extending along a vertical rotation axis; and the optical camera device 202 coupled with the linear element 240.

[0027] In a one embodiment of the system 200 the linear element 240 may be a rotating element (it is indicated in the Fig. 3 with an arrow 20 an example of one possible movement of the linear element 240) able to rotate around a vertical rotation axis, consequently the optical camera device 202 rotates together withthe linear element 204 capturing an image of the at least one hole in a wall of the gas turbine component 231, with respect to the fixed lighting device 203.

[0028] Referring to the Fig. 4 the annular combustion chamber 230 is configured with the inner liner 231 and an outer liner 232, outlining a space between inner liner 231 and outer liner 232.

[0029] Preferably the gas turbine component 231 of the system 200 is an inner liner of an annular combustion chamber 230, in a further embodiment the gas turbine component 231 of the inspection system is the outer liner 232 of the annular combustion chamber 230.

[0030] Advantageously in a second embodiment of the system 200 the linear element 240 may be fixed and the gas turbine component 231 rotates around the linear element 240. In this second embodiment the optical camera device 202, coupled with the linear element 240, and the lighting device 203 are fixed.

[0031] Fig. 5 e Fig. 6 show the inspection system 300, 400 for a gas turbine component 331, 431, wherein the gas turbine component 331, 431 has at least one hole 301, 401 having a free section, comprises: a lighting device 303,403 configured to be located inside the gas turbine component 331, 431 and to light the at least one hole; an optical camera device 302, 402 configured to be located outside the gas turbine component 331, 431 and to receive light from the lighting device 303, 403 through the at least one hole; a shelter device 310, 410 configured to be located outside the gas turbine component 331, 431 and to shelter the optical camera device 302, 402 from ambient light 320, 420; an electronic processing unit 304, 404 coupled at least to optical camera device 302, 402 and configured to calculate an area of the free section of the at least one hole based on an image captured by theoptical camera device 302, 402.

[0032] Preferably the gas turbine component is interposed between the lighting device 303, 403 and the optical camera device 302, 402, and the shelter device 310, 410 is configured to include inside the lighting device 303, 403 and the optical camera device 302, 402, as shown in Fig. 5 e Fig 6.

[0033] Referring to Fig. 6 the system 400, comprising a linear element 440, configured to be located inside the gas turbine component 431, and extending along a vertical rotation axis; and the lighting device 403 coupled with the linear element 440.

[0034] In a one embodiment of the system 400 the linear element 440 may be a rotating element (it is indicated in the Fig. 6 with an arrow 40 an example of one possible movement of the linear element 440) able to rotate around a vertical rotation axis. In this embodiment the optical camera device 402 and the lighting device 403 coupled with the linear element 240, consequently they rotate together with the linear element 440.

[0035] Advantageously in a second embodiment of the system 400 the linear element 440 may be fixed and the gas turbine component 431 rotates around the linear element 440, and the lighting device 403 is fixed.

[0036] Considering Fig. 7 the system comprises a robotic device 600, and a platform 700, wherein the gas turbine component 131, 231, 331, 431 to be inspected is arranged on the platform 700, preferably integrally arranged on the platform 700.

[0037] Advantageously the robotic device 600 comprises two or more robotic arms 610. Each robotic arm 610 is equipped with at least one end coupled respectively with the lighting device 103, 203, 303, 403 and the optical camera device 102, 202, 302, 402.

[0038] With non limiting reference to Figs. 7 and 8 one of the two or more robotic arms 610 is positioned inside the gas turbine component 131, 231, 331, 431, and one of the two or more robotic arms 610 is positioned outside the gas turbine component 131, 231, 331, 431.

[0039] According to a first embodiment (see Fig. 8)the two or more robotic arms 610 are configured to translate along an axis parallel to the axis of the gas turbine component 131, 231, 331, 431 from top to bottom (A) and vice versa in a coordinated manner, and the platform 700 is able to rotate (C) around a rotational axis.

[0040] In a second embodiment (see Fig. 7) the two or more robotic arms 610 are configured to translate along an axis parallel to the axis of the gas turbine component 131, 231, 331, 431 from top to bottom A and vice versa in a coordinated manner, advantageously the platform 700 is fixed and the robotic device 600 is configured to rotate (B) around a vertical axis of the gas turbine component 131, 231, 331, 431 and the optical camera device 102, 202, 302, 402 and the lighting device 103, 203, 303, 403 coupled with each of the two robotic arms 610 rotate together with the robotic device 600.

[0041] Moreover in a third embodiment the robotic arm of the two robotic arms 610 coupled with the lighting device 103, 203, 303, 403 is fixed and the robotic arm of the two robotic arms 610 coupled with the optical camera device 102, 202, 302, 402 is able to translate along an axis parallel to the axis of the gas turbine component 131, 231, 331, 431, in this embodiment the platform 700 is able to rotate (C) around a vertical axis (see Fig.8).

[0042] Instead in a four embodiment the robotic arm of the two robotic arms 610 coupled with the lighting device 103, 203, 303, 403 is fixed and the robotic arm of the two robotic arms 610 coupled with the optical camera device 102, 202, 302, 402 is able to translate along an axis parallel to the axis of the gasturbine component 131, 231, 331, 431, in this embodiment the robotic device 600 is configured to rotate (B) around a vertical axis of the gas turbine component 131, 231, 331, 431 and the platform 700 is fixed. (see Fig. 7)

[0043] As shown in Fig. 9 the system 100, 200, 300, 400 in the last embodiment comprises a robotic device 800, a platform 700, and a fixed light source 900, wherein the robotic device 800 comprises a robotic arm 810 equipped at least at one end with an optical camera device 102, 202, 302, 402; and advantageously the fixed light source 900 is arranged along the vertical axis of the gas turbine component 131, 231, 331, 431.

[0044] Preferably the gas turbine component 131, 231, 331, 431 to be inspected is arranged on the platform 700 integrally arranged on the platform 700.

[0045] Considering Fig. 9 the robotic arm 810 is configured to translate along an axis parallel to the axis of the gas turbine component 131, 231, 331, 431 from top to bottom A and vice versa in a coordinated manner, wherein the platform 700 is able to rotate (C) around a vertical axis.

[0046] Moreover the robotic arm 810 is also configured to translate along an axis parallel to the axis of the gas turbine component 131, 231, 331, 431 from top to bottom (A) and vice versa in a coordinated manner, wherein the robotic device 800 is configured to rotate (B) around a vertical axis of the gas turbine component 131, 231, 331, 431 and the optical camera device 102, 202, 302, 402 coupled with the robotic arm 810 rotates together with the robotic device 800, and the platform 700 is fixed.

[0047] Fig. 10 illustrates a flow chart of an embodiment of the innovative method 500 to determine an area of a free section of at least one hole in a wall of a gas turbine component. The flow chart has a start -block 510 and an endblock 560; the steps between block 510 and block 560 are typically repeated several times during inspection process. According to this embodiment of theinnovative method, these steps are: a) positioning 520 an optical camera device and a lighting device so that the wall is interposed between the lighting device and the optical camera device and so that light from the lighting device reaches the optical camera passing through the at least one hole; b) sheltering 530 the optical camera device from ambient light; c) capturing 540 at least one image by the optical camera device; d) processing 550 the image through an electronic processing unit and calculating the area of the free section of the at least one hole by counting pixels of the image having a brightness greater than a predetermined value, that is calculated based on the image to be processed.

[0048] In particular, the step “b” is carried out through a portion of the gas turbine component or is carried out through a shelter device.

Claims

CLAIMS1. An inspection system (100, 200) for a gas turbine component (131, 231), wherein the gas turbine component (131, 231) has at least one hole (101, 201) having a free section, wherein the inspection system comprises: a lighting device (103, 203) configured to be located outside the gas turbine component (131, 231) and to light the at least one hole (101, 201); an optical camera device (102, 202) configured to be located inside the gas turbine component (131, 231) and to receive light from the lighting device (103, 203) through the at least one hole (101, 201); an electronic processing unit (104, 204) coupled at least to the optical camera device (102, 202) and configured to calculate an area of the free section of the at least one hole (101, 201) based on an image captured by the optical camera device (102, 202). whereby the gas turbine component (131, 231) is interposed between the lighting device (103, 203) and the optical camera device (102, 202) and shelters the optical camera device (102, 202) from ambient light.

2. The system (100) of claim 1, comprising a sliding unit (105) configured to be located inside the gas turbine component (131), wherein said sliding unit comprises: a rail (115) and a trolley (125) connected with the rail (115) by means of a sliding coupling.

3. The system (100) of claim 1, wherein said optical camera device (102) is configured to be located on the trolley (125) of the sliding unit (105), and to capture images of a plurality of holes (101) of the gas turbine component (131).

4. The system (100) of claim 1 wherein the gas turbine component (131) is a combustion chamber liner of a tubular combustion chamber (130).

5. The system (100) of claim 4, wherein the tubular combustion chamber(130) is configured with the liner (131) and an outer case (132), outlining a space between liner (131) and outer case (132).

6. The system (100) of claim 3, wherein the at least one hole (101) is a louver of the combustion chamber liner.

7. The system (200) of claim 1, comprising a linear element (240), configured to be located inside the gas turbine component (231), and extending along a vertical rotation axis.

8. The system (200) of claim 1, wherein the optical camera device (202) is coupled with the linear element (240).

9. The system (200) of claim 7, wherein the linear element (240) is a rotating element, and the optical camera device (202) rotates together with the linear element (204), with respect to the fixed lighting device (203).

10. The system (200) of claim 1, wherein the gas turbine component (231) is an inner liner of an annular combustion chamber (230).

11. The system (200) of claim 10, wherein the annular combustion chamber (230) is configured with the inner liner (231) and an outer liner (232), outlining a space between inner liner (231) and outer liner (232).

12. The system (200) of claim 10, wherein the gas turbine component (231) rotates around the fixed linear element (240), with respect to the fixed lighting device (203).

13. The system (100, 200) of claim 1, wherein said optical camera device (102, 202) comprises a telecentric lens.

14. The system (100, 200) of claim 1, wherein said electronic processing unit (104, 204) is configured to calculate the area of the free section of the at leastone hole (101, 202) by counting pixels of the at least one image.

15. The system (100, 200) of claim 1, wherein said lighting device (103, 203) is a LED light bar, the LED light bar with a wavelength value within a range of 520 -530 nm.

16. An inspection system (300, 400) for a gas turbine component (331, 431), wherein the gas turbine component (331, 431) has at least one hole (301, 401) having a free section, wherein the inspection system comprises: a lighting device (303,403) configured to be located inside the gas turbine component (331, 431) and to light the at least one hole; an optical camera device (302, 402) configured to be located outside the gas turbine component (331, 431) and to receive light from the lighting device (303, 403) through the at least one hole; a shelter device (310, 410) configured to be located outside the gas turbine component (331, 431) and to shelter the optical camera device (302, 402) from ambient light (320, 420); an electronic processing unit (304, 404), coupled at least to the optical camera device (302, 402) and configured to calculate an area of the free section of the at least one hole based on an image captured by the optical camera device (302, 402). whereby the gas turbine component is interposed between the lighting device (303, 403) and the optical camera device (302, 402).

17. The system (300, 400) of claim 16, wherein the shelter device (310, 410) is configured to surround the lighting device (303, 403) and the optical camera device (302, 402).

18. The system (400) of claim 16, comprising a linear element (440), configured to be located inside the gas turbine component (431), and extending along a vertical rotation axis.

19. The system (400) of claim 16, wherein the lighting device (403) is coupled with the linear element (440).

20. The system (400) of claim 18, wherein the linear element (440) is a rotating element, and the optical camera device (402) and the lighting device (403) rotate together with the linear element (440).

21. The system (400) of claim 16, wherein the gas turbine element (431) rotates around the fixed linear element (440), with respect to the fixed lighting device (403).

22. The system (100, 200, 300, 400) of claims 1 and 16, comprising a robotic device (600), and a platform (700), wherein the robotic device (600) comprises two or more robotic arms (610), each robotic arm (610) is equipped with at least one end coupled respectively with the lighting device (103, 203, 303, 403) and the optical camera device (102, 202, 302, 402); wherein the gas turbine component (131, 231, 331, 431) to be inspected is arranged on the platform (700).

23. The system (100, 200, 300, 400) of claim 22, wherein one of the two or more robotic arms (610) is positioned inside the gas turbine component (131, 231, 331, 431), and one of the two or more robotic arms (610) is positioned outside the gas turbine component (131, 231, 331, 431).

24. The system (100, 200, 300, 400) of claim 22, wherein the two or more robotic arms (610) are configured to translate along an axis parallel to the axis of the gas turbine component (131, 231, 331, 431) from top to bottom (A) and vice versa in a coordinated manner, wherein the platform (700) is able to rotate (C) around a vertical axis.

25. The system (100, 200, 300, 400) of claim 22, wherein the two or more robotic arms (610) are configured to translate along an axis parallel to the axis of the gas turbine component (131, 231, 331, 431) from top to bottom (A) and vice versa in a coordinated manner, wherein the robotic device (600) is configured to rotate (B) around a vertical axis of the gas turbine component (131, 231, 331, 431) and the optical camera device (102, 202, 302, 402) and the lighting device (103, 203, 303, 403) coupled with each of the two robotic arms (610) rotate together with the robotic device (600), wherein the platform (700) is fixed.

26. The system (100, 200, 300, 400) of claim 22, wherein the robotic arm of the two robotic arms (610) coupled with the lighting device (103, 203, 303, 403) is fixed and the robotic arm of the two robotic arms (610) coupled with the optical camera device (102, 202, 302, 402) is able to translate along an axis parallel to the axis of the gas turbine component (131, 231, 331, 431), wherein the platform (700) is able to rotate (C) around a vertical axis.

27. The system (100, 200, 300, 400) of claim 22, wherein the robotic arm of the two robotic arms (610) coupled with the lighting device (103, 203, 303, 403) is fixed and the robotic arm of the two robotic arms (610) coupled with the optical camera device (102, 202, 302, 402) is able to translate along an axis parallel to the axis of the gas turbine component (131, 231, 331, 431), wherein the robotic device (600) is configured to rotate (B) around a vertical axis of the gas turbine component (131, 231, 331, 431), wherein the platform (700) is fixed.

28. The system (100, 200, 300, 400) of claims 1 and 16 comprising a robotic device (800), a platform (700), and a fixed light source (900), wherein the robotic device (800) comprises a robotic arm (810) equipped at least at one end with an optical camera device (102, 202, 302, 402); wherein the fixed light source (900) is arranged along the vertical axis of the gas turbine component(131, 231, 331, 431), wherein the gas turbine component (131, 231, 331, 431) to be inspected is arranged on the platform (700).

29. The system (100, 200, 300, 400) of claim 28, wherein the robotic arm (810) is configured to translate along an axis parallel to the axis of the gas turbine component (131, 231, 331, 431) from top to bottom (A) and vice versa in a coordinated manner, wherein the platform (700) is able to rotate (C) around a vertical axis.

30. The system (100, 200, 300, 400) of claim 28, wherein the robotic arm (810) is configured to translate along an axis parallel to the axis of the gas turbine component (131, 231, 331, 431) from top to bottom (A) and vice versa in a coordinated manner, wherein the robotic device (800) is configured to rotate (B) around a vertical axis of the gas turbine component (131, 231, 331, 431) and the optical camera device (102, 202, 302, 402) coupled with the robotic arm (810) rotates together with the robotic device (800), wherein the platform (700) is fixed.

31. A method (500) to determine an area of a free section of at least one hole in a wall of a gas turbine component, comprising the steps of: e) positioning (520) an optical camera device and a lighting device so that the wall is interposed between the lighting device and the optical camera device and so that light from the lighting device reaches the optical camera passing through the at least one hole; f) sheltering (530) the optical camera device from ambient light; g) capturing (540) at least one image by the optical camera device; h) processing (550) the image through an electronic processing unit and calculating the area of the free section of the at least one hole by counting pixels of the image having a brightness greater than apredetermined value.

32. The method (500) of claim 31, wherein step “b” is carried out through a portion of the gas turbine component.

33. The method (500) of claim 31, wherein step “b” is carried out through a shelter device.

34. The method (500) of claim 31, wherein the predetermined value is chosen or calculated based on the image to be processed.

Images