Periscopic optical probes for turbomachines and methods for monitoring turbomachines

Abstract

An optical device (1000) is disclosed for mapping and monitoring a thermal status of rotating components (600) of a turbomachine; the device comprises: a tubular element (100) having an internal cavity that extends from a first end to a second end of the tubular element (100) and that embodies an optical path (500), a cooler (200) located in the tubular element (100) and configured to cool the internal cavity of the tubular element (100) through a plurality of channels located in the cavity of the tubular element (100); an optical arrangement, with periscopic approach, located in the tubular element (100) and configured to produce the optical path (500) in said tubular element (100).

Description

TITLEPeriscopic Optical Probes for Turbomachines and Methods for Monitoring TurbomachinesDESCRIPTIONTECHNICAL FIELD

[0001] The subject matter disclosed herein relates to periscopic optical probes for mapping and monitoring a thermal status of rotating components of turbomachines, in particular gas turbines, during operation thereof, and monitoring methods.BACKGROUND ART

[0002] In general, monitoring the status of internal components of turbomachines is very useful for example in order to avoid or prevent failures avoid performance reduction and perform ad hoc periodic maintenance.

[0003] Patent US 10,533,901 discloses an imaging system for inspecting components of turbomachines. The system includes a sight tube that is cooled by a plurality of cooling channels extending through the sight tube and feeding cooling fluid. An exemplary embodiment is shown in Fig. 2; the sight tube extends into hot gas path of the turbomachine; the sight tube is directed toward a portion of the hot gas path. It is apparent from Fig. 2 that, notwithstanding the cooling of the sight tube, the solution aims at minimizing the contact of the sight tube of the imaging system with the hot gas of the turbomachine as the temperature of the hot gas may easily reach and exceed 1000°C; in fact, only a very small end portion of the sight tube is indeed positioned inside the hot gas path. It is also apparent from Fig. 2 that the portion of the hot has path that can be inspected depends on the orientation of the sight tube.

[0004] It would be desirable to monitor a thermal status, in particular metal temperature, of blades or vanes of a turbomachine with a better view than the prior art and preferably with a full view of them so that a thermography would be possible.

[0005] It would also be desirable to monitor blades or vanes during operation of the turbomachine.

[0006] According to the subject matter disclosed herein a periscopic approach is used. A tubular element embodying an optical path and carrying an optical reflective element at an end may be inserted deep into a flow path of the turbomachine and the optical reflective element may face the blades or vanes.

[0007] It is to be noted that the periscopic approach has already been used in an assembly including a sensor that is configured to measure the temperature of combustion gasses (see Patent US 9,116,051). According to this solution hot gasses may flow into the housing body through a port and reach the sensor.

[0008] Accordingly, it would be desirable to have an effective method for mapping a thermal status of (rotating) components of turbomachines through a periscopic optical probe and so being able to capture e.g. the (metal) temperature map of the (rotating) components and to monitor them.

[0009] Moreover, the following patents are also known:GB1410913 describes an apparatus that measures the temperature of an object by creating a visual image using a TV camera and deriving an electrical signal from the image's intensity. By comparing the object's image with these reference levels, a temperature contour map of the object is created. The light-emitting diode currents can be varied to produce a series of contours, which can be photographed.- EP3206021 describes an apparatus designed for insertion through anopening in the outer casing of a gas turbine engine to inspect internal components at high temperatures. It features an optical sight tube with a lens at the distal end for viewing the interior. The sight tube has cooling grooves in its wall to allow a cooling medium to flow and cool the tube.- US2015049396 describes an optical probe that includes one or more optical elements housed within an inner tube. This inner tube consists of at least two sections that can be separated along its longitudinal axis GB2127174 describes a periscope for a high-temperature reactor that features a water-cooled housing that penetrates the reactor's combustion chamber. An optical system is placed inside the housing, allowing scavenging gas to flow through a gap and keep the front lens clear.

[0010] It would also be desirable to optical device for mapping a thermal status of components of a turbomachine, with an innovative cooler.SUMMARY

[0011] According to one aspect, the subject-matter disclosed herein relates to an optical device for mapping a thermal status of components of a turbomachine, in particular rotating components located in a flow path of a turbomachine, wherein the optical device comprises: a tubular element having an internal cavity that extends from a first end to a second end of the tubular element and that houses an optical path; a cooler located in said tubular element, and configured to cool said internal cavity of said tubular element through a plurality of channels located in said cavity of said tubular element; an optical arrangement, with periscopic approach, located in said tubular element, and configured to produce said optical path in said tubular element.

[0012] According to another aspect, the subject-matter disclosed herein relates to a turbomachine comprising an innovative optical device.

[0013] According to another aspect, the subject-matter disclosed herein relates to a method for monitoring a thermal status of blades or vanes of an operating turbomachine through a periscopic optical probe, wherein IR radiations are: focused through a lens positioned in front of the blades or vanes to be monitored inside a casing of the turbomachine, then reflected through a reflector, then transmitted through an optical path that includes one or more lenses, then detected through an IR image detector positioned outside a casing of the turbomachine.BRIEF DESCRIPTION OF THE DRAWINGS.

[0014] A more complete appreciation of the disclosed embodiments of the invention 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 longitudinal-section view of an embodiment of an innovative optical device, namely a periscope optical probe,Fig. 2 illustrates a schematic cross-section view of a tip portion of Fig. 1, Figs. 3 and 4 illustrates a sectional and perspective view of the tip portion of Fig. 1,Fig. 5 illustrates a schematic view of an embodiment of an innovative turbine engine, andFig. 6 illustrates a flow chart of an embodiment of an innovative monitoring method.DETAILED DESCRIPTION OF EMBODIMENTS

[0015] Turbomachines are essential for industrial processes. However, one usual problem that arises with turbomachine is overheating, due to deterioration of cooling system. Overheating can have severe consequences forturbomachine. It can cause damage to internal components and significantly reduce the turbomachine’s lifespan. Excessive heat leads to a decreased operating life of the components, while on the other side an excessive cooling can lead to decreased performance, reducing engine efficiency.

[0016] Furthermore, overheating affects the overall functionality and decreases operating life of the engine. To prevent overheating in turbomachine, monitoring of temperatures helps to detect any sign of overheating, occurring during the running.

[0017] As disclosed herein, a innovative periscopic optical probe is configured to be inserted partially into the casing of a turbomachine, preferably through an already existing borescope port, for mapping and monitoring a thermal status of e.g. blades or vanes or buckets of turbomachines.

[0018] During operation of the turbomachine, the temperatures inside the machine are high, so it is useful to use a periscopic optical probe to monitor the (e.g. rotating) components of the turbomachine, to prevent failures or on the other side to avoid unnecessary hot parts replacement. The innovative periscope optical probe is configured to tolerate these temperatures, especially the tip portion of optical probe is advantageously able to tolerate the high temperatures that occur inside the flow path.

[0019] As disclosed herein, the innovative periscope optical probe with the following features, can tolerate high temperatures so providing optimal monitoring and mapping of the thermal state of the e.g. rotating components and, for example to capture metal temperature map of rotating bucket components.

[0020] Important features of the innovative periscope optical probe are: miniaturization of the tip portion of the probe made by additive manufacturing with integrated cooling side channels; optical arrangement which compriseshigh temperature anti-reflective coated lenses; the reflecting element is advantageously an optical prism with a high performance reflective coating operating at high temperature guaranteeing large field view, short focus distance and low surface deformation. High reflective coating applied on backend of the prism is designed to optimize energy transmission and imaging quality. Optical components inside the tip portion of the probe are designed keeping focus on low coefficient of thermal expansion in order to provide transmissive qualities in the infrared (IR) and stability at extreme high temperatures.

[0021] Referring now to the drawings, Fig. 1 shows a partial schematic longitudinal-section view of an embodiment of an optical device 1000, namely a periscope optical probe.

[0022] Optical device 1000, is configured to map and monitor a thermal status of rotating components 600 of a turbomachine, the device 1000 comprises: a tubular element 100, with variable cross-section, having an internal cavity that extends from a first end to a second end of the tubular element 100 and that embodies an optical path 500, and being configured for being cooled through cooler 200 located in the tubular element 100 and configured to cool the internal cavity of the tubular element 100; optical arrangement, with periscopic approach, located in the tubular element 100 and configured to produce the optical path 500 in the tubular element 100.

[0023] Referring to Fig. 2, the device 1000 further comprises a tip end portion 110 positioned at the second end of the tubular element; the tip end portion 110 is configured to house a solid optical prism 340 and a focusing lens 330.

[0024] The tip end portion 110 comprises a hole 120 located on the leading side of the tip end portion 110 facing rotating components 600; the tip end portion 110 includes a curved profile 140 on the bottom side of the tip endportion 110.

[0025] The tip end portion 110 is configured to be cooled, through a flow of cooling fluid coming from the cooler 200, in particular to cool the solid optical prism 340, and the focusing lens 330.

[0026] The tubular element 100 is configured to be inserted partially into the casing 731 of a turbomachine (that will be described afterwards with reference to Fig. 3), preferably through already existing borescope port, so that the focusing lens 330 faces the rotating components 600 of the turbomachine.

[0027] The tubular element 100 has a variable cross-section, preferably with a decreasing cross-section; the tip end portion 110 has a smaller diameter than the diameter of the central portion of the tubular element 100, allowing the tip end portion 110 of the tubular element 100 to fit inside the turbomachine close to the rotating components 600, so as to be able to capture the metal temperature map of rotating components 600.

[0028] Referring to Fig. l and Fig.2, the above-mentioned optical arrangement comprises: an optical image detector 310, a plurality of internal lenses 320, a focusing lens 330 and an solid optical prism 340; the optical image detector 310, preferably an IR image detector, is configured to work in Near Infrared portion of spectrum is located at the first end of the tubular element, and is positioned outside a casing 731 of the turbomachine; the plurality of internal lenses 320 are located inside the cavity of the tubular element 100 and configured to focus an image of the rotating components 600 on the optical image detector 310, when the tubular element 100 is inserted partially into the casing of a turbomachine, and to minimize optical attenuation and optimize optical path 500; the focusing lens 330 is located rearwardly and parallel to the hole 120, in front of the solid optical prism 340; the solid optical prism 340, preferably an optical prism with triangular base; at least a support350, is located in the tip end portion 110 of the tubular element 100 and is configured to house the solid optical prism 340 and the focusing lens 330.

[0029] The focusing lens 330 comprises a high temperature anti-reflective coating 360; one or some or all of the internal lenses 320 may also be provided with an anti-reflective coating 360; the anti-reflective coating may be applied to one or both surfaces of any lens (i.e. the front lens and any internal lens).

[0030] The solid optical prism 340 is preferably an optical triangular prism and mainly comprises a first surface 341 disposed rearwardly and parallel to the focusing lens 330, a second surface 342 disposed rearwardly and parallel to a first lens of a plurality of internal lenses 320, and a third surface 343, the outer face of the third surface 343 has a reflective coating 361, a mirror.

[0031] The solid optical prism 340 is an optically transparent triangular solid prism, in particular made of optical material suitable for high temperature operation, and the reflective coating 361, in particular a mirror, on the third surface 343 provides the solid optical prism 340 a low coefficient of thermal expansion, which allows the solid optical prism 340 to exhibit small deformation, and great stability at extremely high temperatures.

[0032] The solid optical prism 340, by means of its reflective surface, is able to focus and redirect at 90° an image of the rotating components 600 and transmitted the image, through the optical path 500, at the optical image detector 310.

[0033] The internal lenses 320 are positioned so to focus an image on the optical image detector 310 when the tubular element 100 is installed in a flow path of a turbomachine in an operating condition corresponding to the flow path at high temperature.

[0034] Cooler 200 comprise a plurality of channels located in the cavity ofthe tubular element 100, in the central part of the tubular element 100; the cooler 200 comprises at least four channels 210 arranged parallel to the axis of the tubular element 100 and extending laterally along the central portion of the cavity

[0035] At least four channels 210 are arranged along the tubular element 100: one of the four channels along the front side in alignment with the hole 120, one of the four along the rear side in alignment with the hole 120, and two of the four extending along the lateral walls of the tubular element 100.

[0036] As shown in Fig. 4 at least four channels 210, preferably two of four channels 210 leading air to right side and left side focusing lens 330 through a lateral cooling slots 362, preferably two lateral cooling slots. Advantageously two others of the four channels 210 leading air to bottom and top side of the focusing lens 330 through a top cooling slot 363a and a bottom cooling slot 363b, This air also acts as a barrier and purging mechanism for the lenses, shielding them from potentially dirty gas

[0037] In the tip end portion 110 of the tubular element 100, the cooler 200 comprise a first channel 220 extending perimetrically along the curved profile 140 of the tip end portion 110 and a second channel 230 connected at one end to the central portion of the first channel 220 and at a second end to the support 350 to facilitate cooling of the solid optical prism 340, and the focusing lens 330, when the tubular element 100 is installed in a flow path of a turbomachine in an operating condition at high temperature.

[0038] One end of the first channel 220 is closely connected to a lower end of one of the two channels 210 along the rear side of the tip end portion 110, diametrically opposite to the hole 120, and a second end of the first channel 220 is disposed near the hole 120 on the front side of the tip end portion 110 to facilitate cooling of the focusing lens 330 and the solid optical prism 340when the tubular element 100 is installed in a flow path of a turbomachine in an operating condition at high temperature.

[0039] As shown in Fig. 3 the second end of the first channel 220 leading cooling air at the bottom of focusing lens 330 through a bottom cooling slot 363a and referring to Fig. 3 a second end of the second channel 230 leading cooling air to the solid optical prism 340. Advantageously the cooling slots 362, 363a, 363b are openings designed to allow air to flow. This air also acts as a barrier and purging mechanism for the lenses, shielding them from potentially dirty and sooty gas coming from the combustion chamber.

[0040] Referring to Fig. 5 an innovative turbine engine 700 comprises: a compressor 710, a combustion chamber 720, that sits between the compressor and turbine, a gas turbine 730. The gas turbine 730, that is a turbomachine, has a casing 731. An innovative optical device 1000 is inserted partially into the casing 731 of the gas turbine 730, in particular through a borescope port so that a front lens of the optical device 1000 faces rotating components of the gas turbine 730. The optical device 1000 is kept mounted to the gas turbine 730 during operation of the turbine engine 700.

[0041] Fig. 6 illustrates a flow chart 2000 of an embodiment a method for monitoring and mapping a thermal status of blades or vanes of an operating turbomachine through a periscopic optical probe. The flow chart has a start block 2100 and an end block 2600; the steps corresponding to block 2200 to block 2500 are typically repeated several times during monitoring of the turbomachine. According to an innovative method, IR radiations are: focused (see block 2200) through a lens positioned in front of the blades or vanes to be monitored inside a casing of the turbomachine, then reflected (see block 2300) through a reflector,then- transmitted (see block 2400) through an optical path, that including one or more lenses, then - detected (see block 2500) through an IR image detector positioned outside a casing of the turbomachine.

Claims

CLAIMS1. An optical device (1000) for mapping a thermal status of components (600) of a turbomachine in particular rotating components located in a flow path of a turbomachine, wherein the optical device (1000) comprises: a tubular element (100) having an internal cavity that extends from a first end to a second end of the tubular element (100) and that houses an optical path (500); a cooler (200) located in said tubular element (100), and configured to cool said internal cavity of said tubular element (100) through a plurality of channels located in said cavity of said tubular element (100); an optical arrangement, with periscopic approach, located in said tubular element (100), and configured to produce said optical path (500) in said tubular element (100). wherein the cooler (200), in a tip end portion (110) of said tubular element (100), comprises a first channel (220) extending perimetrically along a curved profile (140) of the tip end portion (110) and a second channel (230) connected at one end to a central portion of the first channel (220) and at a second end to a support (350) of a solid optical prism (340) of the optical arrangement.

2. The optical device (1000) of claim 1, wherein said cooler (200), in a central part of the tubular element (100), comprises at least four channels (210) arranged parallel to a central axis of said tubular element (100) and extending laterally along a central portion of said cavity, respectively one of the four along a front side in alignment with said hole (120), one of the four along a rear side in alignment with the hole (120), and two of the four extending along a lateral walls of the tubular element (100).

3. The optical device (1000) of claim 2, wherein said one end of said first channel (220) is closely connected to a lower end of one of said two channels (210) along the rear side of the tip end portion (110), diametrically opposite to said hole (120), and a second end of said first channel (220) is located close to said hole (120) on the front side of the tip end portion (110).

4. The optical device (1000) of claim 1, wherein said second end of said first channel (220) leading cooling air at the bottom of a focusing lens (330) through a bottom cooling slot (363b).

5. The optical device (1000) of claim 1, wherein a second end of the second channel (230) leading cooling air to the solid optical prism (340).

6. The optical device (1000) of claim 3, wherein two of the four channels (210) leading air to right side and left side of the focusing lens (330) through a lateral cooling slots (362), and two others of the four channels (210) leading air to bottom side of the focusing lens (330) through a bottom cooling slot (363b) and top side of the focusing lens (330) through a top cooling slot (363a)7. The optical device (1000) of claim 1, wherein said optical arrangement comprises: the solidal optical prism (340), located at the second end of said tubular element (100); the focusing lens (330) located in front of said solid optical prism (340); a plurality of internal lenses (320) located inside said internal cavity of said tubular element (100).

8. The optical device (1000) of claim 7, wherein the solid optical prism (340) comprising a first surface (341) located rearwardly and parallel to said focusing lens (330), a second surface (342) located rearwardly and parallel to a first lens of a plurality of said internal lenses (320), and a third surface (343), wherein the outer face of said third surface (343) has a reflective coating (361).

9. The optical device (1000) of claim 1, wherein the optical device (1000) further comprises the tip end portion (110) positioned at the second end of said tubular element (100), the tip end portion being configured to house said solid optical prism (340) and said focusing lens (330).

10. The optical device (1000) of claim 9, wherein said tip end portion (110) comprises a hole (120) located on the leading side of said tip end portion (110) faces said components (600).

11. The optical device (1000) of claims 9, wherein said tip end portion (110) is configured to be cooled, in particular through a flow of cooling fluid coming from said cooler (200); wherein said solid optical prism (340) is preferably cooled. wherein said focusing lens (330) is preferably cooled.

12. The optical device (1000) of claim 1, comprising high temperature anti-reflective coating (360) positioned on said focusing lens (330) and a reflective coating (361) positioned on a surface (343) of said solid optical prism (340).

13. The optical device (1000) of claim 7, wherein one or both surfaces of said front focusing lens (330) and / or one or both surfaces of one or some or all of said internal lenses (320) are provided with an anti-reflective coating (360).

14. The optical device (1000) of claim 7, wherein said internal lenses (320) are positioned so to focus an image on said optical image detector (310) when said tubular element (100) is installed in a flow path of a turbomachine (700) in an operating condition corresponding to the flow path at high temperature.

15. Aturbomachine (730) comprising an optical device (1000) according to claim 1.

16. The turbomachine (730) of claim 15, wherein the optical device (1000) is inserted partially into a casing (731) of the turbomachine (730) through a borescope port so that a front lens of the optical device (1000) faces rotating components (600) of the turbomachine (730), and is kept mounted to the turbomachine (730) during operation of the turbomachine (730).

17. The turbomachine (730) of claim 15 being configured as a gas turbine.

18. A method (2000) for monitoring a thermal status of blades or vanes of an operating turbomachine through a periscopic optical probe, wherein IR radiations are: focused (2200) through a lens positioned in front of the blades or vanes to be monitored inside a casing of the turbomachine, then reflected (2300) through a reflector, then- transmitted (2400) through an optical path that includes one or more lenses,then detected (2500) through an IR image detector positioned outside the casing of the turbomachine.

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