Fluid detection device in a turbomachine

Abstract

A device (20) for detecting fluid in an internal region (21) of an operating turbomachine (1), said device (20) comprising: - an acquisition system (22) disposed away from the turbomachine (1), - a light source (25) disposed in the vicinity of the acquisition system (22) and adapted to emit a light flux extending over at least one fluorescence or phosphorescence wavelength of the fluid, - an elongated element (23) extending between the acquisition system (22) and the internal region (21) of the turbomachine (1), comprising at least one optical fiber (25) connected to the light source (25), and - an optical detection device (26, 28) disposed in the internal region (21), adapted to detect a fluorescence light flux emitted by the fluid in the internal region (21). Figure to be published with the abbreviation: 2

Description

Title of the invention: Device for detecting fluid in a turbomachine Technical field of the invention

[0001] The present invention belongs to the field of quality control in aeronautics. It relates more particularly to a device for detecting a fluid, and in particular oil, in an internal region of a turbomachine.

[0002] The invention also relates to a method for detecting a fluid, and in particular oil, using this device. State of the prior art

[0003] [Fig. 1] illustrates a prior art dual-flow turbojet engine 1, intended to equip an aircraft, in particular an airplane. The turbojet engine 1 extends along an axis X and comprises, from upstream to downstream in the direction of circulation of the gases F, a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6 and a low-pressure turbine 7. The low- and high-pressure compressors 3, 4, the combustion chamber 5 and the high- and low-pressure turbines 6, 7 are located in a so-called primary vein 8. A so-called secondary vein 9 extends around the primary vein 8, downstream of the fan 2.

[0004] The terms axial, radial and circumferential are defined relative to the X axis of the turbomachine. The terms upstream and downstream are defined relative to the direction of gas flow within the turbomachine.

[0005] The low-pressure compressor 3 and the low-pressure turbine 7 together form a low-pressure body, and are connected to each other by a low-pressure shaft 11 centered on the X axis. Similarly, the high-pressure compressor 4 and the high-pressure turbine 6 form a high-pressure body, and are connected to each other by a high-pressure shaft 13 centered on the X axis and arranged around the low-pressure shaft 11. The shafts 11, 13 are supported by rolling bearings, which are lubricated by being arranged in oil chambers. The same applies to a hub 15 of the fan 2, also supported by rolling bearings.

[0006] These oil chambers containing the rolling bearings are likely to cause oil leaks in different internal regions of the turbomachine 1.

[0007] These oil leaks are currently observed by endoscopy on stationary turbomachines.

[0008] However, these inspection methods do not allow the appearance and development of these leaks to be visualized, which we wish to observe with the engine in operation, an important condition allowing a better understanding of the phenomenon and the corrective solutions considered. Such an observation is made particularly complex by the severity of the environment constituted by a turbomachine in operation, with very high temperatures and pressures and very little space available, which greatly reduces the sensitivity of the detection and risks damaging the sensors. Presentation of the invention

[0009] The invention aims to remedy these drawbacks. To this end, the invention relates to a device for detecting a fluid in an internal region of a turbomachine in operation, said device comprising:

[0010] - an acquisition system arranged away from the turbomachine,

[0011] - a light source arranged in the vicinity of the acquisition system or in the internal region and adapted to emit a luminous flux extending over at least one fluorescence or phosphorescence wavelength of the fluid,

[0012] - an elongated element extending between the acquisition system and the internal region of the turbomachine, comprising at least one cable and / or at least one optical fiber connected to the light source, and

[0013] - an optical detection device arranged in the internal region, adapted for detect a luminous flux of fluorescence or phosphorescence emitted by the fluid in the internal region.

[0014] Such a device makes it possible to detect the presence of fluid, in particular oil, in situ, in the form of drops and / or suspension in the air, in a turbomachine in operation. Indeed, the optical detection method by fluorescence or phosphorescence is compact and robust and makes it possible to overcome the constraints of such a severe environment in terms of temperature and pressure, while maintaining sufficient sensitivity.

[0015] The cable and / or the optical fiber allows electronic signals for controlling the light source, or an illumination light flux, to be transmitted between the internal region and the acquisition system.

[0016] It is recalled that fluorescence is a phenomenon of light emission by matter following external excitation, in particular light. Phosphorescence is a similar phenomenon, except that the emissions persist for longer periods, even once the external excitation has stopped.

[0017] Most oils naturally exhibit such a fluorescence range.

[0018] The device according to the invention can be used to detect any type of fluid, by means, in certain cases, of a prior injection or projection of a fluorescent or phosphorescent marker in the region observed, for fluids with little or no fluorescent or phosphorescent, or simply to enhance the amount of light emitted by the fluid.

[0019] The turbomachine is considered to be in operation when at least the low pressure shaft or the high pressure shaft is rotating rapidly, so as to generate an air flow in the main vein.

[0020] The optical detection device may comprise at least one endoscopic camera arranged in the internal region of the turbomachine, the elongated element comprising at least one cable connecting said endoscopic camera to the acquisition system.

[0021] Such a characteristic allows direct in-situ visual observation of the fluid, and also allows the implementation of conventional image processing techniques making it possible to obtain information characterizing the presence of the fluid.

[0022] The optical detection device may comprise at least one optical probe disposed in the internal region of the turbomachine, the elongated element comprising at least one second optical fiber connecting said optical probe to the acquisition system.

[0023] Such a feature makes it possible to relocate sensitive components by performing the analysis of the light flux outside the turbomachine.

[0024] The acquisition system may comprise a spectrometer connected to the optical probe by the second optical fiber.

[0025] Such a characteristic makes it possible to detect the fluid by fluorescence or phosphorescence with high sensitivity thanks to the analysis of the spectrum of the fluorescence or phosphorescence light.

[0026] The device may comprise a photomultiplier disposed in the internal region or in the vicinity of the acquisition system and connected to the optical probe directly or through the second optical fiber.

[0027] Such a characteristic makes it possible to measure a highly intermittent presence of fluid (fall of a drop of oil, vaporization of oil) thanks to the wide bandwidth of the photomultiplier.

[0028] The acquisition system may comprise a bandpass type optical filter, centered on a fluorescence or phosphorescence wavelength of the fluid, positioned between the acquisition system and the optical probe.

[0029] Said filter may be located, depending on the case, between the optical probe and the second optical fiber, between the optical probe and the photomultiplier or between the second optical fiber and the acquisition device.

[0030] Such a characteristic makes it possible to improve the sensitivity of the detection.

[0031] The device may also comprise means for projecting into the internal region a fluorescent or phosphorescent marker or dye, capable of mixes with the fluid and has a similar or identical fluorescence or phosphorescence wavelength.

[0032] Such a characteristic makes it possible to increase the quantity of light emitted by fluorescence or phosphorescence and therefore to improve the measured optical signal and therefore to have better sensitivity.

[0033] The light source may comprise a light-emitting diode and / or a laser diode, capable of emitting at the excitation wavelength of the fluorescence or phosphorescence of the fluid.

[0034] Such a characteristic makes it possible to reduce the emission of parasitic visible light by the source.

[0035] The light source may be substantially monochromatic.

[0036] Such a characteristic makes it possible to ensure that the measured light signal corresponds to the fluorescence of the fluid.

[0037] The invention also relates to a method for detecting fluid in an internal region of a turbomachine in operation, the method implementing a device as above and comprising the following steps:

[0038] - emission of a luminous flux by the light source and routing of the flux light from the source to the internal region by optical fiber, or control of the light source located in the internal region through the cable,

[0039] - illumination of the fluid in the internal region and emission by the fluid of a flow luminous fluorescence, and

[0040] - detection of the fluorescence light flux by the optical detection device. Brief description of the figures

[0041] [Fig-1] is a schematic representation in longitudinal section of an aircraft turbomachine,

[0042] [Fig.2] is a simplified representation in longitudinal section of an aircraft turbomachine equipped with a detection device according to the invention,

[0043] [Fig.3] is a schematic representation of a detection device according to a first embodiment of the invention,

[0044] [Fig.4] is a schematic representation of a detection device according to a second embodiment of the invention, and

[0045] [Fig.5] is a graphical representation of light spectra measured in the presence and absence of oil. Detailed description of the invention

[0046] [Fig.2] represents in a simplified manner a turbomachine 1 similar to that of [Fig.l], with identical references designating the same objects, provided with a fluid detection device 20 according to the invention.

[0047] The device 20 is capable of detecting the presence of oil in an internal region 21 of the turbomachine 1 in operation.

[0048] As explained above, the device 20 is capable of detecting any type of fluorescent or phosphorescent fluid in the region of interest, in particular oil, which is the fluid considered for the example described here. The device 20 can also be used to detect non-fluorescent or phosphorescent fluids by adding a fluorescent or phosphorescent marker to the fluid.

[0049] The turbomachine is considered to be in operation when at least the low pressure shaft 11 or the high pressure shaft 13 is rotating rapidly around the axis X, so as to generate an air flow in the main vein.

[0050] The internal region 21 is difficult to access, since it is isolated from the outside by one or more casings defining the primary and secondary veins. Thus, direct observation methods do not allow said internal region 21 to be observed to conclude as to the presence of oil.

[0051] The device 20 comprises an acquisition system 22 located outside the internal region 21, as well as an elongated element 23 extending between said acquisition system 22 and the internal region 21 and a light source 24 arranged in the vicinity of the acquisition system 22.

[0052] The elongated element 23 is in particular a bundle comprising at least one optical fiber and, optionally, at least one cable. The elongated element 23 is adapted to follow a tortuous path in the turbomachine 1 to the internal region 21, and to allow a transfer of information and power, in light and / or electrical form.

[0053] Alternatively, the light source 24 may be placed in the internal region 21 and driven through at least one electrical cable forming part of the elongate element 23.

[0054] The exact nature of the elongate element 23 varies according to the embodiments of the invention, as shown below.

[0055] The light source 24 is adapted to emit light radiation allowing the oil to fluoresce.

[0056] In particular, the light radiation has a wavelength spectrum comprising at least one wavelength absorbed by the oil and triggering the fluorescence / phosphorescence phenomenon (the spectrum of the source is different from the fluorescence or phosphorescence spectrum emitted by the oil).

[0057] Said fluorescence wavelength of the oil is for example a wavelength in the near ultraviolet, for example close to 385 nanometers.

[0058] Advantageously, the light radiation is substantially monochromatic, particularly in the ultraviolet, which allows the absence of parasitic visible light in the region of interest.

[0059] The light source 24 is for example a laser source or a light-emitting diode.

[0060] The elongated element 23 comprises, in the example considered, at least one optical fiber 25 connected to the output of the light source 24 and opening into the region of interest 21, so as to convey the fluorescence radiation there and illuminate the oil which could be present there.

[0061] Alternatively, when the source 24 is located in the internal region 21, the elongated element 23 comprises at least one cable for controlling the source 24, and may comprise at least one optical fiber, depending on the nature of the acquisition device.

[0062] Advantageously, the elongated element 23 may also comprise a capillary tube allowing the projection into a relevant region of a fluorescent or phosphorescent marker or dye, which mixes with the oil and also allows the sensitivity of the detection to be increased.

[0063] It is notably possible to mix a phosphorescent marker with the oil and illuminate it upstream of the internal region to be observed, in order to then observe it by taking advantage of the prolonged emission of light by phosphorescence.

[0064] In a first embodiment shown in [Fig.3], the optical method of oil detection is observation by an endoscopic type camera.

[0065] For this purpose, the device 20 comprises, in addition to the elements described above, an endoscopic camera 26 arranged in the internal region 21, and an electrical cable 27 connecting said camera 26 to the acquisition system 22 to power and control the camera 26.

[0066] Thanks to the radiation coming from the source 24 and, where appropriate, supplied by the optical fiber 25, the oil present in the internal region 21, in the form of suspension in the air or drops deposited on the walls, fluoresces and becomes clearly visible with the camera 26.

[0067] The acquisition system 22 then comprises a computer system for image control and processing, which allows the recording of images and / or videos by the camera 26. It also allows the implementation of image processing algorithms, to determine certain parameters associated with the observed oil, for example a concentration or a distribution of the oil between suspension and deposited drops.

[0068] A second embodiment is shown in [Fig.4], implementing a measurement by spectroscopy.

[0069] The acquisition system 22 then comprises a spectrometer 29 and a computer module 30 for controlling and processing the spectroscopy results.

[0070] The elongated element 23 comprises the optical fiber 25 described above connected to the output of the light source 24 and illuminating the internal region 21, as well as a second optical fiber 27a connected to the input of the spectrometer 29 and the free end of which is connected, in the internal region 21, to an optical probe 28 opposite the illuminated region.

[0071] Alternatively, when the source 24 is located in the internal region, the elongated element 23 comprises at least the control cable of the source 24 and the second optical fiber 27a mentioned above.

[0072] The second optical fiber 27a is adapted to collect the light emitted in the region of interest, in particular by the fluorescence of the oil, and to convey it to the spectrometer 29 to be analyzed.

[0073] The spectrometer 29 is adapted to analyze the light spectrum of the light collected by the probe 28 in the internal region 21.

[0074] [Fig.5] represents spectra of light power P as a function of the wavelength X at the input of the spectrometer 29. A first spectrum Sa is obtained for an internal region containing only air, and a second spectrum Sh is obtained for an internal region containing air and oil in the form of drops and / or suspension in the air.

[0075] The Sh spectrum shows a peak at a fluorescence wavelength Xf, distinctive of the presence of oil in the internal region 21, the area of ​​which makes it possible to qualitatively evaluate the quantity of oil observed as a function of time.

[0076] Advantageously, an optical filter 31 of the bandpass type, centered on the fluorescence wavelength, can be positioned upstream of the spectrometer 29 to increase the sensitivity of the detection.

[0077] According to another embodiment similar to that shown in [Fig.4], the acquisition system 22 comprises a photomultiplier 29 connected to an optical probe 28 arranged in the region of interest 21 via the second optical fiber 27a, as well as the control module 30.

[0078] The photomultiplier 29 is configured to amplify the amount of light collected by the optical probe 28 and convert it into an electrical voltage. When oil located in the internal region 21 fluoresces, the increased amount of light collected by the probe 28 results in a change in the measured voltage.

[0079] A band-pass filter 31 centered on the fluorescence wavelength of the oil can be positioned upstream of the photomultiplier 29, which makes it possible to filter only a range of light wavelengths characteristic of the presence of oil. Thus, the accuracy of the detection increases.

[0080] Since the photomultiplier 29 has a very wide bandwidth, it is also possible to measure a highly intermittent presence of oil (fall of a drop of oil, vaporization of oil).

Claims

Claims

1. Device (20) for detecting a fluid in an internal region (21) of a turbomachine (1) in operation, said device (20) comprising: - an acquisition system (22) arranged away from the turbomachine (1), - a light source (25), arranged in the vicinity of the acquisition system (22) or in the internal region (21), and adapted to emit a light flux extending over at least one fluorescence or phosphorescence wavelength of the fluid, - an elongated element (23) extending between the acquisition system (22) and the internal region (21) of the turbomachine (1), comprising at least one cable and / or at least one optical fiber (25) connected to the light source (25), and - an optical detection device (26, 28) arranged in the internal region (21), adapted to detect a fluorescence or phosphorescence light flux emitted by the fluid in the internal region (21), wherein the optical detection device (26,28) comprises at least one optical probe (28) arranged in the internal region (21) of the turbomachine (1), the elongated element comprising at least one second optical fiber (27a) connecting said optical probe (28) to the acquisition system (22), and in which the device (20) comprises a photomultiplier (29) arranged in the internal region (21) or in the vicinity of the acquisition system (22) and connected to the optical probe (28) directly or through the second optical fiber (27a).,

2. Device (20) according to the preceding claim, wherein the optical detection device (26, 28) comprises at least one endoscopic camera (26) arranged in the internal region (21) of the turbomachine (1), the elongated element comprising at least one cable (27) connecting said endoscopic camera (26) to the acquisition system (22).

3. Device (20) according to claim 1 or 2, wherein the acquisition system (22) comprises a spectrometer (29) connected to the optical probe (28) by the second optical fiber (27a).

4. Device (20) according to one of claims 1 to 3, in which the acquisition system comprises an optical filter (31) of the pass-type band, centered on a fluorescence (Xf) or phosphorescence wavelength of the fluid, positioned between the acquisition system (22) and the optical probe (28).

5. Device (20) according to one of claims 1 to 4, in which the device (20) also comprises means for projecting into the internal region (21) a fluorescent or phosphorescent marker or dye, capable of mixing with the fluid and having a close or identical fluorescence or phosphorescence wavelength.

6. Device (20) according to one of the preceding claims, in which the light source (24) comprises a light-emitting diode and / or a laser diode, capable of emitting at the excitation wavelength of the fluorescence or phosphorescence of the fluid.

7. Device (20) according to one of the preceding claims, in which the light source (24) is substantially monochromatic.

8. A method for detecting fluid in an internal region (21) of a turbomachine (1) in operation, the method implementing a device (20) according to one of the preceding claims and comprising the following steps: - emitting a light flux by the light source (24) and conveying the light flux from the source (24) to the internal region (21) by the optical fiber (25), or controlling the light source (24) located in the internal region (21) through the cable, - illuminating the fluid in the internal region (21) and emitting by the fluid a fluorescence or phosphorescence light flux, and - detecting the fluorescence or phosphorescence light flux by the optical detection device (26, 28).

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