EP1647801A2 - Apparatus and method of using the apparatus for measuring the axial displacement of the tips of the blades of a turbomachine in ground tests - Google Patents

Apparatus and method of using the apparatus for measuring the axial displacement of the tips of the blades of a turbomachine in ground tests Download PDF

Info

Publication number
EP1647801A2
EP1647801A2 EP05109335A EP05109335A EP1647801A2 EP 1647801 A2 EP1647801 A2 EP 1647801A2 EP 05109335 A EP05109335 A EP 05109335A EP 05109335 A EP05109335 A EP 05109335A EP 1647801 A2 EP1647801 A2 EP 1647801A2
Authority
EP
European Patent Office
Prior art keywords
blades
camera
images
image
probe
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05109335A
Other languages
German (de)
French (fr)
Inventor
Nadine Harivel
Vincent Leignel
Denis André Jean Lisiecki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Safran Aircraft Engines SAS
Original Assignee
SNECMA SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SNECMA SAS filed Critical SNECMA SAS
Publication of EP1647801A2 publication Critical patent/EP1647801A2/en
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/003—Arrangements for testing or measuring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/04—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for responsive to undesired position of rotor relative to stator or to breaking-off of a part of the rotor, e.g. indicating such position

Definitions

  • the invention relates to a device for measuring the axial displacement of the blade tips of a turbomachine for ground tests and a method of using the device.
  • a turbojet engine generally comprises a fan, one or more compressor stages, a combustion chamber, one or more turbine stages and an ejection nozzle.
  • the blower, the compressor and the turbine comprise rotors whose vanes are rotated about the axis of the turbojet engine.
  • the rotating elements of the turbojet engine are subjected, in operation, to numerous mechanical and thermal stresses, which induce expansions and displacements within their structures. It is therefore important, prior to the development of a turbojet engine, to implement ground tests to quantify these displacements and dimension the structure of the turbojet engine accordingly.
  • the invention relates to measuring the axial displacement of the blade tips of a rotor of a turbomachine, in particular a rotor of a turbojet engine.
  • This measurement is generally performed in ground mode in a test bench.
  • a strip of optical fibers is used, housed at the right of the blades in a bore of their retention housing, provided for this purpose.
  • the bar comprises an alignment of juxtaposed optical fibers in which light beams are emitted; the beams are or are not reflected by the top of the blades, according to whether they are at the right of the latter or not.
  • the axial displacement of the blade tips is deduced from the number of fibers whose beam is reflected.
  • This device has various disadvantages.
  • these optical fibers are fragile and have a significant probability of rupture during the introduction of the bar or its transport.
  • the implementation and implementation on the turbojet of such a device is also very restrictive.
  • the aim of the invention is to propose a device that overcomes the disadvantages mentioned above.
  • the invention relates to a device for measuring the axial displacement of the top of the vanes of a rotor of a turbomachine, for ground tests, characterized in that it comprises means for taking pictures and conduction of images arranged to be implanted at the right of the blades and connected to remote means of image acquisition.
  • the invention it is possible to measure the axial displacement of the blade tips by means of a device, whose image taking and image conduction means have easy access to the blades, providing images with a large number of images. good definition thanks to its image acquisition means, remote and therefore placed in a place of little constraint, the device having a longer life than the devices of the prior art.
  • the device comprises means for generating light.
  • the device comprises synchronization means of the light generating means and image acquisition means.
  • the synchronization means are controlled by the rotation frequency of the blades.
  • the device comprises image processing means connected to the image acquisition means.
  • the image-taking and image-conduction means comprise a fiberscope.
  • the image-taking and image-conduction means comprise an endoscope.
  • the invention also relates to a method for measuring the axial displacement of the top of the vanes of a rotor of a turbomachine for ground tests with the device above.
  • the invention is particularly applicable to measuring the axial displacement of the top of the blades of a rotor of a turbojet, but it goes without saying that the applicant does not intend to limit the scope of its protection to this application alone .
  • the invention applies to any turbomachine comprising a rotor with vanes; the term "ground tests” means tests performed on a test bench on the ground as opposed to tests in air operation for a turbojet engine.
  • the tips of the vanes of its rotors can undergo axial displacements on the axis of the turbojet engine, between their position when the engine is stopped. turbojet engine and their operating position. These displacements must be measured, prior to the commissioning of a turbojet, in order to be able to model the behavior of the blades in operation and size the turbojet engine accordingly.
  • one sets up devices for measuring the axial displacements of the top of the blades used during ground tests of the turbojet engine. In the latter, the turbojet engine is placed in a test bench and put into operation.
  • a device 1 for measuring the axial displacement of the blade tip of a turbojet rotor according to the invention will be described, in connection with the measurement of the axial displacement of the top of the blades 2 of a compressor of a turbojet.
  • These blades 2 extend radially around the axis 3 of the turbojet, around which they are rotatably mounted. They are contained in a casing 4.
  • the function of the device 1 is to measure the axial displacement of the top of the blades 2 during operation of the turbojet engine during ground tests.
  • the device comprises image-taking and image-conduction means 5, which here comprise an optical probe 5, which may in this case be a fiberscope or an endoscope, as will be seen below.
  • the probe 5 is housed in a bore 9 of the compressor casing 4, which is specially drilled for the ground tests. It is placed at the right of the blades 2 to take pictures of their summit.
  • the optical probe 5 is connected to image acquisition means 6, whose function here is to convert the images into a digital video signal, which may comprise, for example, a digital camera or a sensor.
  • image acquisition means 6 whose function here is to convert the images into a digital video signal, which may comprise, for example, a digital camera or a sensor.
  • a digital camera 6 of the CCD type which comprises an electronic shutter that can be opened or closed to make or not the acquisition of images.
  • the probe 5 ensures the taking of pictures at the level of the blades 2 and the conduction of the images towards the camera 6.
  • the camera 6 can either be connected to the probe 5 at its end opposite to that opposite the apex of the 2, or be connected to the probe 5 by additional means of conduction images, for example optical fibers.
  • the camera 6 is connected to means 8 for processing the video signal that it transmits, by appropriate means.
  • the camera 6, as well as the processing means 8, are contained in a computer 7, shown schematically in Figure 1 by a tower and a screen.
  • a device 10 for generating light in this case a strobe 10, is provided, connected to the optical probe 5 by optical fibers 11.
  • the stroboscope 10 and the camera 6 are controlled by a device 12 for synchronizing the flashes of the stroboscope 10 and the electronic shutter of the camera 6.
  • the synchronization device 12 is connected to the stroboscope 10 via means 13 of coupling optical, well known to those skilled in the art.
  • the synchronization device 12 is also connected to the camera 6, which it controls, as well as to the optical probe 5, which allows looping of its servocontrol.
  • the turbojet comprises means for counting the speed motor, that is to say here the frequency of rotation of the compressor blades 2, not shown, connected to a divider 14 which controls the synchronization device 12, to which it is connected by appropriate means.
  • the operation of the device 1 for measuring the axial displacement of the top of the blades 2 of the compressor will now be explained in more detail, in relation to a particular measuring method.
  • the device 1 is used here to measure the axial displacement of the top of the blades 2 of the turbojet compressor, in this case the axial displacement of their leading edge.
  • the method could easily be adapted to measure the axial displacement of their trailing edge.
  • the optical probe 5 is mounted in its receiving bore 9 of the housing 4.
  • the probe 5 may comprise a thread cooperating with a thread of the bore 9 and / or be inserted with a seal.
  • the bore 9 is pierced from outside the housing 4 and opens on its inner wall, near the top of the blades 2.
  • the probe 5 comprises an optical system for taking pictures and conduction images.
  • the probe 5 can be either a fiberscope or an endoscope, which will be described later.
  • a transparent window can be arranged at the internal orifice of the bore 9, in order to ensure the continuity of the gas stream and thus not to disturb the flow of the latter, while allowing images to be taken by the probe 5.
  • the probe 5 also ensuring the tightness of the bore 9. Moreover, the probe 5 itself can ensure, by its end portion, the continuity of the gas stream.
  • the probe 5 is connected to the image acquisition means 6, here the digital camera 6.
  • the camera 6 can be directly connected to the probe 5, if it is not so placed in a too crowded location of the turbojet engine and that it does not suffer from its operating regime in this place. It is well to this extent deported means of shooting.
  • the camera 6 can be deported further still, for example on a structure of the turbojet, connected to the probe by additional means of conduction images, for example optical fibers.
  • the camera 6 is then connected to the image processing means 8 by appropriate means, typically electrical conductors.
  • the camera 6 can also be directly incorporated in the computer 7, as in the case in question, connected to the probe by optical fibers.
  • the computer 7 is here located in a control room of the test bench in which the turbojet engine is disposed, in this case about ten meters from the probe 5. It also comprises the means 8 for processing the images to which the camera 6 is connected.
  • the strobe 10 is here placed on or near the turbojet, and connected to the probe by the optical fibers 11, arranged in a circular arc, closed or not, around the optical probe 5.
  • the strobe flashes light that illuminate, through the optical fibers 11, the space of the turbojet engine located right of the probe 5, the inner side, and therefore a possible blade 2 passing at this point at the time of the flash.
  • a blade 2 is placed at the right of the probe 5 and a first shot is taken, when stopped, which gives the position at the stop of the top of the blades 2.
  • the strobe 10 is lit synchronously with the opening of the electronic shutter of the camera 6, which thus acquires images of the top of the blade 2, transmitted to it by the probe 5 and the optical fibers of conduction images.
  • This first shot also makes it possible to perform optical adjustment of the probe 5 and adjustment of the power of the stroboscope 10 in order to obtain an optimal contrast of the image. It also makes it possible to ensure the synchronization of the emission of a flash by the strobe 10 with the opening of the shutter of the camera 6, so that the camera actually acquires an image when the flash is on, it is ie the top of the dawn 2 lit up.
  • the turbojet engine is operated. When a predetermined speed is reached, shots of the top of a particular blade 2 are taken. Shooting can be done continuously as the speed of the engine changes, the signal emitted by the camera 6 being a video signal.
  • the synchronization device 12 is controlled by the divider 14. The latter is controlled by the engine speed counting device, which serves as a time base for the device.
  • the divider 14 is arranged to send a signal to the synchronization device 12 every "n" turns of the turbojet engine. This signal causes the synchronization device 12 to transmit a signal for sending a flash by the stroboscope 10 and synchronously acquiring an image by the camera 6 by opening its shutter.
  • the blade tip 2 is illuminated by the flash and the shutter of the camera 6 is open to acquire the image of the illuminated blade tip 2.
  • the number "n” is arranged so that the trigger signal always corresponds to the same blade 2.
  • the same blade tip 2 is located at the right of the probe 5 at each emission of a strobe flash and the opening of the shutter of the camera 6.
  • the synchronization device is for this purpose initialized on this particular blade 2, hereinafter referred to as the blade 2, and divides the frequency of rotation or frequency of passage of the blades 2 by "n", so that each image is taken after n turns of the blade 2.
  • the number “n” is arranged to obtain a frequency of the trigger signal which is equal to the desired acquisition frequency for the camera 6.
  • the camera 6 is arranged to capture 50 images per second, "n” being arranged so that the rotation frequency of the blades 2, divided by "n", is equal to 50 Hz or close to 50 Hz.
  • the duration of illumination of the blade tip and the duration of opening of the shutter of the camera 6 are calibrated according to the turbojet engine speed to obtain the most contrasting images possible, but the times are not too low for that the illumination and the acquisition are sufficient, according to the sensitivity of the video sensors of the camera 6.
  • the synchronization of the strobe 10 and the electronic shutter of the camera 6 is done continuously according to the turbojet engine speed . At each image acquisition, the entire synchronization system, which is looped, is synchronized again with respect to the turbojet engine speed.
  • the camera 6 is a camera interlaced frames, each image being acquired in an image of which every other line of all lines is illuminated, alternately every other image.
  • the images are thus acquired at 25 Hz for each of the two sets of lines of a line on two.
  • the images of each line are processed to be interpolated by calculation between two successive taps and assigned to them, for the unlit lines, the value calculated by the interpolation. It goes without saying that the images could be complete as soon as they are acquired.
  • the shutter of the camera 6 can remain open, the flash being lit only during the passage of the blade 2 every "n" turns.
  • the video would then have black periods, or just with ambient light, and illuminated periods.
  • a constant light could illuminate the blades 2, the shutter of the camera 6 being set to be open only every "n" turns of the blade 2.
  • the speed of opening and closing of the shutter of the camera 6 being smaller than that of the ignition and the extinction of the strobe 10, it is better that the capture accuracy of the blade 2 is provided by the strobe 10.
  • the images acquired by the camera 6 are processed in the processing means 8 located in the computer 7. Once the processed images to be complete on all their lines, they are analyzed. It is possible that stray lights, other than the image light from the top of the blade 2, appear on the images. These parasitic lights may in particular come from various reflections in the enclosure containing the blades 2, for example on the walls of the blades 2 or on their feet, reflections related to the coupling between the optical fibers 11 of the strobe 10 and the probe 5. These parasitic lights are filtered in the processing device 8, either by luminous thresholding of the image, or by deleting portions of the image having identifiable parasitic lights, which we know a priori that they can not correspond to the apex of the image. 2.
  • the signal noise is also suppressed using a low-pass filter. This extracts the image from the top of the blade 2 of the image. Next, the closest point to the edge of the image is sought to take account of any misalignments of the probe 5 with the blade 2, for example by scanning the image from the bottom upwards in order to obtain the position of the dawn top 2.
  • the images are in digital format and therefore consist of pixels.
  • the objective of the method of use of the device 1 being the measurement of the axial displacement of the top of the blades 2, the positions of the blades 2 at the various operating speeds of the turbojet engine are compared to their calculated position when stopped; these differences in pixel positions must then be converted into distances.
  • it may be previously carried out the acquisition of images of a control object, of known dimensions, placed at a distance from the probe 5 substantially equal to that at which is placed the top of the blades 2, in order to calculate a conversion factor of pixels in millimeters, for example.
  • the axial displacements of the blades represent, for a blower, 10 to 20 mm, for a high-pressure compressor of a turbofan engine, 5 to 10 mm, for a low-pressure compressor, 1 to 5 mm .
  • the device of the invention and to its method of use, it is therefore possible to measure, in real time, on a turbojet engine operating during ground tests, the axial displacements of the top of the blades by means of acquisition of deported images with respect to the shooting means, to which they are connected by means means of conduction of images.
  • the imaging frequency of the device is adapted in real time to the operating speed of the turbojet engine.
  • the probe of the device 1 is a fiberscope 5a. It comprises a flexible optical conduit 15, comprising a plurality of optical fibers in parallel, in this case numbering 10,000.
  • the optical conduit 15 is bonded to a ferrule 16, housed in a sleeve 17 for coupling to the casing 4 of the compressor.
  • the sleeve 17 comprises a head portion 18 for connecting the fibers 11 connected to the stroboscope 10, in which the ferrule 16 is housed, which is extended by a hollow tubular portion 19 forming with it a bearing shoulder 20 on the housing 4
  • the ferrule 16 may also extend in the tubular portion 19.
  • the latter has an external thread 21, which is screwed into a corresponding bore of the casing 4, thereby sealing the assembly.
  • the ferrule 16 opens into the inner duct of the tubular portion 19, which extends through the bore 9 of the casing 4, and is therefore located at the place of passage of the leading edge of the top of the blades 2, which it takes images.
  • the fibers 11 connected to the stroboscope 10, not shown, here extend in a partial arc around the ferrule 16.
  • the fiberscope 5a is connected directly to the camera 6 by its optical conduit 15.
  • the fiberscope 5a can be mounted in very difficult to access and congested areas.
  • the images obtained are diaphragmed by the circular entrance pupil of the light of the ferrule 16, forming means of shooting.
  • the images are discretized because of the juxtaposition of the optical fibers.
  • the probe of the device 1 is an endoscope 5b. It comprises a rigid optical conduit 22.
  • This conduit 22 typically comprises a metal conduit, in which are arranged in series lenses, spaced apart from each other by their focal length, not shown.
  • the rigid optical conduit 22 is housed in a sleeve 23 of connection to the casing 4 of the compressor.
  • the sleeve 23 comprises a head portion 24, connecting the fibers 11 connected to the stroboscope 10, and a hollow tubular portion 25.
  • the tubular portion 25 has an external thread 26, which is screwed into a corresponding bore of the housing 4, thus ensuring the tightness of the whole.
  • the optical duct 22 opens into the internal duct of the tubular portion 25, which is extended by the bore 9 of the casing 4, and is therefore at the right of the place of passage of the leading edge of the top of the blades 2, which she takes the images.
  • the fibers 11 connected to the stroboscope 10, not shown, here extend in a partial arc around the optical duct 22.
  • the camera 6 can be mounted at the outer end of the optical conduit 22, if space permits, by a connector.
  • the optical conduit 22 thus provides a shooting function, by its internal end, and an image conduction function to the camera 6.
  • the optical conduit 22 can also be connected to other means of conduction images typically optical fibers, in turn connected to the camera 6.
  • the endoscope 5b is slightly more restrictive to mount than the fiberscope 5a.
  • the images that it takes are not discretized as for the fiberscope 5a, the lighting being able to be better, which provides images of better resolution.
  • the field of the filmed object if it is more precise, is on the other hand smaller, because of the magnification by the lenses; this magnification also implies that the apparent speed of the blades in front of the endoscope 5b is all the greater, which requires a better precision in the shooting so that the images are not too fuzzy and do not involve drag or trace too important because of the movement of the blades.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The device has an optical probe (5) installed at right side of blades (2) and is connected to a CCD type digital camera (6). A stroboscope (10) is connected to the probe via optical fibers (11). A synchronization device (12) is controlled by frequency of rotation of the blades and is connected to the stroboscope and the camera. The camera acquires the image which is processed by an image processing unit (8). An independent claim is also included for a process for measuring axial displacement of the rotor blade of a turbomachine for testing at the ground.

Description

L'invention concerne un dispositif de mesure du déplacement axial du sommet des aubes d'un e turbomachine pour des essais au sol et un procédé d'utilisation du dispositif.The invention relates to a device for measuring the axial displacement of the blade tips of a turbomachine for ground tests and a method of using the device.

Un turboréacteur comprend généralement une soufflante, un ou plusieurs étages de compresseur, une chambre de combustion, un ou plusieurs étages de turbine et une tuyère d'éjection. La soufflante, le compresseur et la turbine comprennent des rotors, dont les aubes sont entraînées en rotation autour de l'axe du turboréacteur.A turbojet engine generally comprises a fan, one or more compressor stages, a combustion chamber, one or more turbine stages and an ejection nozzle. The blower, the compressor and the turbine comprise rotors whose vanes are rotated about the axis of the turbojet engine.

Les éléments rotatifs du turboréacteur sont soumis, en fonctionnement, à de nombreuses contraintes mécaniques et thermiques, qui induisent des dilatations et des déplacements au sein de leurs structures. Il est dès lors important, avant la mise au point d'un turboréacteur, de mettre en oeuvre des essais au sol pour quantifier ces déplacements et dimensionner la structure du turboréacteur en conséquence.The rotating elements of the turbojet engine are subjected, in operation, to numerous mechanical and thermal stresses, which induce expansions and displacements within their structures. It is therefore important, prior to the development of a turbojet engine, to implement ground tests to quantify these displacements and dimension the structure of the turbojet engine accordingly.

L'invention concerne la mesure du déplacement axial du sommet des aubes d'un rotor d'une turbomachine, en particulier d'un rotor d'un turboréacteur.The invention relates to measuring the axial displacement of the blade tips of a rotor of a turbomachine, in particular a rotor of a turbojet engine.

Cette mesure est généralement effectuée en fonctionnement au sol dans un banc d'essais. On utilise une barrette de fibres optiques, logée au droit des aubes dans un alésage de leur carter de rétention, prévu à cet effet. La barrette comporte un alignement de fibres optiques juxtaposées, dans lesquelles sont émis des faisceaux lumineux ; les faisceaux sont ou non réfléchis par le sommet des aubes, selon qu'ils se trouvent au droit de ces dernières ou pas. Le déplacement axial du sommet des aubes est déduit du nombre de fibres dont le faisceau est réfléchi.This measurement is generally performed in ground mode in a test bench. A strip of optical fibers is used, housed at the right of the blades in a bore of their retention housing, provided for this purpose. The bar comprises an alignment of juxtaposed optical fibers in which light beams are emitted; the beams are or are not reflected by the top of the blades, according to whether they are at the right of the latter or not. The axial displacement of the blade tips is deduced from the number of fibers whose beam is reflected.

Ce dispositif présente divers inconvénients. Tout d'abord, sa précision est faible et directement liée au diamètre des fibres optiques, en l'espèce 0,25 mm. En outre, ces fibres optiques sont fragiles et présentent une probabilité non négligeable de rupture lors de la mise en place de la barrette ou de son transport. Or, il est impossible de remplacer une seule fibre dans une barrette lorsqu'elle est cassée ; c'est la barrette entière qu'il faut remplacer lors de la rupture d'une fibre. Une barrette possédant souvent plusieurs centaines de fibres d'une dizaine de mètres, le coût de remplacement est très élevé. La mise en oeuvre et l'implantation sur le turboréacteur d'un tel dispositif est par ailleurs très contraignante.This device has various disadvantages. First, its accuracy is low and directly related to the diameter of the optical fibers, in this case 0.25 mm. In addition, these optical fibers are fragile and have a significant probability of rupture during the introduction of the bar or its transport. However, it is impossible to replace a single fiber in a bar when it is broken; it is the entire bar that must be replaced when breaking a fiber. A bar often having several hundred fibers of ten meters, the replacement cost is very high. The implementation and implementation on the turbojet of such a device is also very restrictive.

On a pensé remplacer ce dispositif par une caméra, présentant l'intérêt d'une résolution plus grande, d'une part, et d'une plus grande robustesse, d'autre part. Toutefois, l'encombrement d'une caméra est trop important pour qu'elle soit mise en place de façon satisfaisante sur un turboréacteur, qui présente de nombreux obstacles à sa périphérie. Une caméra supporte mal de surcroît les contraintes vibratoires en fonctionnement d'un turboréacteur.It was thought to replace this device with a camera, presenting the interest of a larger resolution, on the one hand, and a greater robustness, on the other hand. However, the size of a camera is too important for it to be implemented satisfactorily on a turbojet, which has many obstacles on its periphery. In addition, a camera does not withstand the vibratory stresses during operation of a turbojet engine.

L'invention vise à proposer un dispositif palliant les inconvénients énoncés ci-dessus.The aim of the invention is to propose a device that overcomes the disadvantages mentioned above.

A cet effet, l'invention concerne un dispositif de mesure du déplacement axial du sommet des aubes d'un rotor d'une turbomachine, pour des essais au sol, caractérisé par le fait qu'il comprend des moyens de prise de vues et de conduction d'images agencés pour être implantés au droit des aubes et reliés à des moyens déportés d'acquisition des images.To this end, the invention relates to a device for measuring the axial displacement of the top of the vanes of a rotor of a turbomachine, for ground tests, characterized in that it comprises means for taking pictures and conduction of images arranged to be implanted at the right of the blades and connected to remote means of image acquisition.

Grâce à l'invention, il est possible de mesurer le déplacement axial du sommet des aubes grâce à un dispositif, dont les moyens de prise de vues et de conduction d'images ont un accès aisé au droit des aubes, fournissant des images avec une bonne définition grâce à ses moyens d'acquisition des images, déportés et donc placés en un lieu peu contraignant, le dispositif ayant une durée de vie supérieure à celle des dispositifs de l'art antérieur.Thanks to the invention, it is possible to measure the axial displacement of the blade tips by means of a device, whose image taking and image conduction means have easy access to the blades, providing images with a large number of images. good definition thanks to its image acquisition means, remote and therefore placed in a place of little constraint, the device having a longer life than the devices of the prior art.

De préférence, le dispositif comprend des moyens de génération de lumière.Preferably, the device comprises means for generating light.

Avantageusement dans ce cas, le dispositif comprend des moyens de synchronisation des moyens de génération de lumière et des moyens d'acquisition des images.Advantageously in this case, the device comprises synchronization means of the light generating means and image acquisition means.

Avantageusement encore, les moyens de synchronisation sont commandés par la fréquence de rotation des aubes.Advantageously, the synchronization means are controlled by the rotation frequency of the blades.

De préférence, le dispositif comprend des moyens de traitement des images reliés aux moyens d'acquisition des images.Preferably, the device comprises image processing means connected to the image acquisition means.

Selon une première forme de réalisation, les moyens de prise de vues et de conduction d'images comprennent un fibroscope.According to a first embodiment, the image-taking and image-conduction means comprise a fiberscope.

Selon une deuxième forme de réalisation, les moyens de prise de vues et de conduction d'images comprennent un endoscope.According to a second embodiment, the image-taking and image-conduction means comprise an endoscope.

L'invention concerne également un procédé de mesure du déplacement axial du sommet des aubes d'un rotor d'une turbomachine pour des essais au sol avec le dispositif ci-dessus.The invention also relates to a method for measuring the axial displacement of the top of the vanes of a rotor of a turbomachine for ground tests with the device above.

L'invention s'applique particulièrement bien à la mesure du déplacement axial du sommet des aubes d'un rotor d'un turboréacteur, mais il va de soi que la demanderesse n'entend pas limiter l'étendue de sa protection à cette seule application. L'invention s'applique à toute turbomachine comportant un rotor avec des aubes ; par l'expression "essais au sol", on entend des essais effectués sur un banc d'essai au sol par opposition à des essais en fonctionnement aérien pour un turboréacteur.The invention is particularly applicable to measuring the axial displacement of the top of the blades of a rotor of a turbojet, but it goes without saying that the applicant does not intend to limit the scope of its protection to this application alone . The invention applies to any turbomachine comprising a rotor with vanes; the term "ground tests" means tests performed on a test bench on the ground as opposed to tests in air operation for a turbojet engine.

L'invention sera mieux comprise à l'aide à la description suivante du dispositif et du procédé de l'invention, en référence aux planches annexées, sur lesquelles :

  • la figure 1 représente une vue schématique fonctionnelle du dispositif de l'invention ;
  • la figure 2 représente une vue en coupe schématique de la sonde optique d'une première forme de réalisation du dispositif de l'invention ;
  • la figure 3 représente une vue en coupe schématique de la sonde optique d'une deuxième forme de réalisation du dispositif de l'invention.
The invention will be better understood with the help of the following description of the device and method of the invention, with reference to the attached plates, in which:
  • Figure 1 shows a schematic functional view of the device of the invention;
  • FIG. 2 represents a schematic sectional view of the optical probe of a first embodiment of the device of the invention;
  • FIG. 3 represents a schematic sectional view of the optical probe of a second embodiment of the device of the invention.

En raison des contraintes mécaniques, aérodynamiques et thermiques de fonctionnement sur l'ensemble des éléments constitutifs d'un turboréacteur, les sommets des aubes de ses rotors peuvent subir des déplacements axiaux sur l'axe du turboréacteur, entre leur position à l'arrêt du turboréacteur et leur position en régime de fonctionnement. Ces déplacements doivent être mesurés, préalablement à la mise en service d'un turboréacteur, afin de pouvoir modéliser le comportement des aubes en fonctionnement et dimensionner le turboréacteur en conséquence. A cet effet, on met en place des dispositifs de mesure des déplacements axiaux du sommet des aubes, utilisés lors d'essais au sol du turboréacteur. Dans ces derniers, le turboréacteur est placé dans un banc d'essai et mis en fonctionnement.Due to the mechanical, aerodynamic and thermal operating constraints on all the constituent elements of a turbojet engine, the tips of the vanes of its rotors can undergo axial displacements on the axis of the turbojet engine, between their position when the engine is stopped. turbojet engine and their operating position. These displacements must be measured, prior to the commissioning of a turbojet, in order to be able to model the behavior of the blades in operation and size the turbojet engine accordingly. For this purpose, one sets up devices for measuring the axial displacements of the top of the blades, used during ground tests of the turbojet engine. In the latter, the turbojet engine is placed in a test bench and put into operation.

En référence à la figure 1, un dispositif 1 de mesure du déplacement axial du sommet des aubes d'un rotor de turboréacteur selon l'invention va être décrit, en relation avec la mesure du déplacement axial du sommet des aubes 2 d'un compresseur d'un turboréacteur. Ces aubes 2 s'étendent radialement autour de l'axe 3 du turboréacteur, autour duquel elles sont montées rotatives. Elles sont contenues dans un carter 4. Le dispositif 1 a pour fonction de mesurer le déplacement axial du sommet des aubes 2 en fonctionnement du turboréacteur, lors d'essais au sol.Referring to Figure 1, a device 1 for measuring the axial displacement of the blade tip of a turbojet rotor according to the invention will be described, in connection with the measurement of the axial displacement of the top of the blades 2 of a compressor of a turbojet. These blades 2 extend radially around the axis 3 of the turbojet, around which they are rotatably mounted. They are contained in a casing 4. The function of the device 1 is to measure the axial displacement of the top of the blades 2 during operation of the turbojet engine during ground tests.

Le dispositif comprend des moyens 5 de prise de vues et de conduction d'images, qui comprennent ici une sonde optique 5, qui peut être en l'espèce un fibroscope ou un endoscope, comme on le verra plus loin. La sonde 5 est logée dans un alésage 9 du carter 4 du compresseur, spécialement percé pour les essais au sol. Elle est placée au droit des aubes 2 pour prendre des images de leur sommet.The device comprises image-taking and image-conduction means 5, which here comprise an optical probe 5, which may in this case be a fiberscope or an endoscope, as will be seen below. The probe 5 is housed in a bore 9 of the compressor casing 4, which is specially drilled for the ground tests. It is placed at the right of the blades 2 to take pictures of their summit.

La sonde optique 5 est reliée à des moyens 6 d'acquisition des images, dont la fonction est ici de convertir les images en signal vidéo numérique, qui peuvent comprendre par exemple une caméra numérique ou un capteur. Il s'agit dans le cas d'espèce considéré d'une caméra numérique 6 de type CCD, qui comporte un obturateur électronique pouvant être ouvert ou fermé pour faire ou non l'acquisition d'images. La sonde 5 assure la prise de vues au niveau des aubes 2 et la conduction des images vers la caméra 6. A cet effet, la caméra 6 peut, soit être connectée à la sonde 5 à son extrémité opposée à celle en regard du sommet des aubes 2, soit être connectée à la sonde 5 par des moyens supplémentaires de conduction des images, par exemple des fibres optiques.The optical probe 5 is connected to image acquisition means 6, whose function here is to convert the images into a digital video signal, which may comprise, for example, a digital camera or a sensor. In this case, it concerns a digital camera 6 of the CCD type, which comprises an electronic shutter that can be opened or closed to make or not the acquisition of images. The probe 5 ensures the taking of pictures at the level of the blades 2 and the conduction of the images towards the camera 6. For this purpose, the camera 6 can either be connected to the probe 5 at its end opposite to that opposite the apex of the 2, or be connected to the probe 5 by additional means of conduction images, for example optical fibers.

La caméra 6 est reliée à des moyens 8 de traitement du signal vidéo qu'elle émet, par des moyens appropriés. En l'espèce, la caméra 6, ainsi que les moyens de traitement 8, sont contenus dans un ordinateur 7, schématisé sur la figure 1 par une tour et un écran.The camera 6 is connected to means 8 for processing the video signal that it transmits, by appropriate means. In this case, the camera 6, as well as the processing means 8, are contained in a computer 7, shown schematically in Figure 1 by a tower and a screen.

Un dispositif 10 de génération de lumière, en l'espèce un stroboscope 10, est prévu, relié à la sonde optique 5 par des fibres optiques 11. La lumière, guidée par les fibres optiques 11 convenablement agencées à proximité de la sonde 5, éclaire le sommet des aubes 2 lorsque le stroboscope 10 émet un flash. Par flash, on entend un éclat de lumière bref. Le stroboscope 10 et la caméra 6 sont commandés par un dispositif 12 de synchronisation des flashs du stroboscope 10 et de l'obturateur électronique de la caméra 6. Le dispositif de synchronisation 12 est relié au stroboscope 10 par l'intermédiaire de moyens 13 de couplage optique, bien connus de l'homme du métier. Le dispositif de synchronisation 12 est également relié à la caméra 6, qu'il commande, ainsi qu'à la sonde optique 5, qui permet un bouclage de son asservissement. Le turboréacteur comporte des moyens de comptage du régime moteur, c'est-à-dire ici de la fréquence de rotation des aubes 2 du compresseur, non représentés, reliés à un diviseur 14 qui commande le dispositif de synchronisation 12, auquel il est relié par des moyens appropriés.A device 10 for generating light, in this case a strobe 10, is provided, connected to the optical probe 5 by optical fibers 11. The light, guided by the optical fibers 11 suitably arranged near the probe 5, illuminates the top of the blades 2 when the strobe 10 emits a flash. By flash, we hear a brief flash of light. The stroboscope 10 and the camera 6 are controlled by a device 12 for synchronizing the flashes of the stroboscope 10 and the electronic shutter of the camera 6. The synchronization device 12 is connected to the stroboscope 10 via means 13 of coupling optical, well known to those skilled in the art. The synchronization device 12 is also connected to the camera 6, which it controls, as well as to the optical probe 5, which allows looping of its servocontrol. The turbojet comprises means for counting the speed motor, that is to say here the frequency of rotation of the compressor blades 2, not shown, connected to a divider 14 which controls the synchronization device 12, to which it is connected by appropriate means.

Le fonctionnement du dispositif 1 de mesure du déplacement axial du sommet des aubes 2 du compresseur va maintenant être expliqué plus en détails, en relation avec un procédé de mesure particulier. Le dispositif 1 est ici utilisé pour mesurer le déplacement axial du sommet des aubes 2 du compresseur du turboréacteur, en l'espèce le déplacement axial de leur bord d'attaque. On pourrait aisément adapter le procédé pour mesurer le déplacement axial de leur bord de fuite.The operation of the device 1 for measuring the axial displacement of the top of the blades 2 of the compressor will now be explained in more detail, in relation to a particular measuring method. The device 1 is used here to measure the axial displacement of the top of the blades 2 of the turbojet compressor, in this case the axial displacement of their leading edge. The method could easily be adapted to measure the axial displacement of their trailing edge.

La sonde optique 5 est montée dans son alésage de réception 9 du carter 4. La sonde 5 peut comporter un filetage coopérant avec un filetage de l'alésage 9 et/ou être insérée avec un joint d'étanchéité. L'alésage 9 est percé depuis l'extérieur du carter 4 et débouche sur sa paroi interne, à proximité du sommet des aubes 2. La sonde 5 comprend un système optique de prise de vues et de conduction des images. Selon les deux formes de réalisations préférées de l'invention, la sonde 5 peut être soit un fibroscope, soit un endoscope, qui seront décrits plus loin. Un hublot transparent peut être disposé au niveau de l'orifice interne de l'alésage 9, afin d'assurer la continuité de la veine de gaz et ainsi ne pas perturber l'écoulement de ce dernier, tout en permettant la prise de vues par la sonde 5. Toutefois, dans certaines conditions, il n'est pas nécessaire de prévoir un hublot, si la perturbation induite par l'orifice de l'alésage 9 n'est pas trop importante, la sonde 5 assurant par ailleurs l'étanchéité de l'alésage 9. Par ailleurs, la sonde 5 elle-même peut assurer, par sa portion d'extrémité, la continuité de la veine de gaz.The optical probe 5 is mounted in its receiving bore 9 of the housing 4. The probe 5 may comprise a thread cooperating with a thread of the bore 9 and / or be inserted with a seal. The bore 9 is pierced from outside the housing 4 and opens on its inner wall, near the top of the blades 2. The probe 5 comprises an optical system for taking pictures and conduction images. According to the two preferred embodiments of the invention, the probe 5 can be either a fiberscope or an endoscope, which will be described later. A transparent window can be arranged at the internal orifice of the bore 9, in order to ensure the continuity of the gas stream and thus not to disturb the flow of the latter, while allowing images to be taken by the probe 5. However, under certain conditions, it is not necessary to provide a window, if the disturbance induced by the orifice of the bore 9 is not too great, the probe 5 also ensuring the tightness of the bore 9. Moreover, the probe 5 itself can ensure, by its end portion, the continuity of the gas stream.

La sonde 5 est reliée aux moyens d'acquisition des images 6, ici la caméra numérique 6. La caméra 6 peut être directement connectée à la sonde 5, si tant est qu'elle ne soit pas ainsi placée dans un lieu trop encombré du turboréacteur et qu'elle ne souffre pas de son régime de fonctionnement dans ce lieu. Elle est bien dans cette mesure déportée des moyens de prise de vues. La caméra 6 peut être déportée plus loin encore, par exemple sur une structure du turboréacteur, reliée à la sonde par des moyens supplémentaires de conduction des images, par exemple des fibres optiques. Dans les deux cas qui viennent d'être envisagés, la caméra 6 est alors reliée aux moyens 8 de traitement des images par des moyens appropriés, typiquement des conducteurs électriques. La caméra 6 peut aussi être directement incorporée à l'ordinateur 7, comme dans le cas d'espèce considéré, reliée à la sonde par des fibres optiques. L'ordinateur 7 est ici situé dans une salle de commande du banc d'essai dans lequel le turboréacteur est disposé, en l'espèce à une dizaine de mètre de la sonde 5. Il comporte également les moyens 8 de traitement des images auxquels la caméra 6 est connectée.The probe 5 is connected to the image acquisition means 6, here the digital camera 6. The camera 6 can be directly connected to the probe 5, if it is not so placed in a too crowded location of the turbojet engine and that it does not suffer from its operating regime in this place. It is well to this extent deported means of shooting. The camera 6 can be deported further still, for example on a structure of the turbojet, connected to the probe by additional means of conduction images, for example optical fibers. In the two cases just considered, the camera 6 is then connected to the image processing means 8 by appropriate means, typically electrical conductors. The camera 6 can also be directly incorporated in the computer 7, as in the case in question, connected to the probe by optical fibers. The computer 7 is here located in a control room of the test bench in which the turbojet engine is disposed, in this case about ten meters from the probe 5. It also comprises the means 8 for processing the images to which the camera 6 is connected.

Le stroboscope 10 est ici placé sur le turboréacteur, ou à proximité de ce dernier, et relié à la sonde par les fibres optiques 11, disposées en arc de cercle, fermé ou non, autour de la sonde optique 5. Le stroboscope émet des flash lumineux qui éclairent, par le biais des fibres optiques 11, l'espace du turboréacteur situé au droit de la sonde 5, du côté interne, et donc une éventuelle aube 2 passant à cet endroit au moment du flash.The strobe 10 is here placed on or near the turbojet, and connected to the probe by the optical fibers 11, arranged in a circular arc, closed or not, around the optical probe 5. The strobe flashes light that illuminate, through the optical fibers 11, the space of the turbojet engine located right of the probe 5, the inner side, and therefore a possible blade 2 passing at this point at the time of the flash.

Afin d'initialiser le procédé, on place une aube 2 au droit de la sonde 5 et une première prise de vues est effectuée, à l'arrêt, qui donne la position à l'arrêt du sommet des aubes 2. A cet effet, le stroboscope 10 est allumé de manière synchronisée avec l'ouverture de l'obturateur électronique de la caméra 6, qui acquiert ainsi des images du sommet de l'aube 2, transmises jusqu'à elle par la sonde 5 et les fibres optiques de conduction des images. Cette première prise de vues permet également d'effectuer un réglage optique de la sonde 5 et un réglage de la puissance du stroboscope 10 afin d'obtenir un contraste optimal de l'image. Elle permet également d'assurer la synchronisation de l'émission d'un flash par le stroboscope 10 avec l'ouverture de l'obturateur de la caméra 6, afin que la caméra acquiert effectivement une image lorsque le flash est allumé, c'est-à-dire le sommet de l'aube 2 éclairé.In order to initialize the process, a blade 2 is placed at the right of the probe 5 and a first shot is taken, when stopped, which gives the position at the stop of the top of the blades 2. For this purpose, the strobe 10 is lit synchronously with the opening of the electronic shutter of the camera 6, which thus acquires images of the top of the blade 2, transmitted to it by the probe 5 and the optical fibers of conduction images. This first shot also makes it possible to perform optical adjustment of the probe 5 and adjustment of the power of the stroboscope 10 in order to obtain an optimal contrast of the image. It also makes it possible to ensure the synchronization of the emission of a flash by the strobe 10 with the opening of the shutter of the camera 6, so that the camera actually acquires an image when the flash is on, it is ie the top of the dawn 2 lit up.

Le turboréacteur est mis en fonctionnement. Lorsqu'un régime prédéterminé est atteint, on effectue des prises de vues du sommet d'une aube 2 particulière. Les prises de vues peuvent être faites de façon continue au fur et à mesure de l'évolution du régime du moteur, le signal émis par la caméra 6 étant un signal vidéo. A cet effet, le dispositif de synchronisation 12 est commandé par le diviseur 14. Ce dernier est commandé par le dispositif de comptage du régime moteur, qui sert de base temporelle au dispositif. Le diviseur 14 est agencé de façon à envoyer un signal au dispositif de synchronisation 12 tous les "n" tours du turboréacteur. Ce signal provoque l'émission, par le dispositif de synchronisation 12, d'un signal de commande d'émission d'un flash par le stroboscope 10 et d'acquisition synchronisée d'une image par la caméra 6 par ouverture de son obturateur. Ainsi, à chaque signal de déclenchement, le sommet d'aube 2 est éclairé par le flash et l'obturateur de la caméra 6 est ouvert pour acquérir l'image du sommet d'aube 2 éclairé.The turbojet engine is operated. When a predetermined speed is reached, shots of the top of a particular blade 2 are taken. Shooting can be done continuously as the speed of the engine changes, the signal emitted by the camera 6 being a video signal. For this purpose, the synchronization device 12 is controlled by the divider 14. The latter is controlled by the engine speed counting device, which serves as a time base for the device. The divider 14 is arranged to send a signal to the synchronization device 12 every "n" turns of the turbojet engine. This signal causes the synchronization device 12 to transmit a signal for sending a flash by the stroboscope 10 and synchronously acquiring an image by the camera 6 by opening its shutter. Thus, at each trigger signal, the blade tip 2 is illuminated by the flash and the shutter of the camera 6 is open to acquire the image of the illuminated blade tip 2.

Le nombre "n" est agencé de manière à ce que le signal de déclenchement corresponde toujours à la même aube 2. Ainsi, le même sommet d'aube 2 se situe au droit de la sonde 5 à chaque émission d'un flash du stroboscope et d'ouverture de l'obturateur de la caméra 6. Le dispositif de synchronisation est pour cela initialisé sur cette aube 2 particulière, désignée ci-après l'aube 2, et divise la fréquence de rotation ou fréquence de passage des aubes 2 par "n", de manière à ce que chaque image soit prise après n tours de l'aube 2. Le nombre "n" est agencé de manière à obtenir une fréquence du signal de déclenchement qui soit égale à la fréquence d'acquisition souhaitée pour la caméra 6. En l'espèce, la caméra 6 est agencée pour capturer 50 images par seconde, "n" étant donc agencé de façon à ce que la fréquence de rotation des aubes 2, divisée par "n", soit égale à 50 Hz ou voisine de 50 Hz.The number "n" is arranged so that the trigger signal always corresponds to the same blade 2. Thus, the same blade tip 2 is located at the right of the probe 5 at each emission of a strobe flash and the opening of the shutter of the camera 6. The synchronization device is for this purpose initialized on this particular blade 2, hereinafter referred to as the blade 2, and divides the frequency of rotation or frequency of passage of the blades 2 by "n", so that each image is taken after n turns of the blade 2. The number "n" is arranged to obtain a frequency of the trigger signal which is equal to the desired acquisition frequency for the camera 6. In this case, the camera 6 is arranged to capture 50 images per second, "n" being arranged so that the rotation frequency of the blades 2, divided by "n", is equal to 50 Hz or close to 50 Hz.

La durée d'éclairement du sommet d'aube et la durée d'ouverture de l'obturateur de la caméra 6 sont calibrés en fonction du régime du turboréacteur pour obtenir des images les plus contrastées possibles, sans toutefois que les durées soient trop faibles pour que l'éclairement et l'acquisition soient suffisants, en fonction de la sensibilité des capteurs vidéo de la caméra 6. La synchronisation du stroboscope 10 et de l'obturateur électronique de la caméra 6 se fait de manière continue en fonction du régime du turboréacteur. A chaque prise d'image, l'ensemble du système de synchronisation, qui est bouclé, est synchronisé de nouveau par rapport au régime du turboréacteur.The duration of illumination of the blade tip and the duration of opening of the shutter of the camera 6 are calibrated according to the turbojet engine speed to obtain the most contrasting images possible, but the times are not too low for that the illumination and the acquisition are sufficient, according to the sensitivity of the video sensors of the camera 6. The synchronization of the strobe 10 and the electronic shutter of the camera 6 is done continuously according to the turbojet engine speed . At each image acquisition, the entire synchronization system, which is looped, is synchronized again with respect to the turbojet engine speed.

En l'espèce, la caméra 6 est une caméra à trames entrelacées, chaque image étant acquise en une image dont une ligne sur deux, de l'ensemble des lignes, est éclairée, alternativement une image sur deux. Les images sont donc acquises à 25 Hz pour chacun des deux ensembles de lignes d'une ligne sur deux. Pour obtenir des images complètes remplissant l'ensemble des trames, les images de chaque ligne sont traitées pour être interpolées par calcul entre deux prises successives et leur assigner, pour les lignes non éclairées, la valeur calculée par l'interpolation. Il va de soi que les images pourraient être complètes dès leur acquisition.In this case, the camera 6 is a camera interlaced frames, each image being acquired in an image of which every other line of all lines is illuminated, alternately every other image. The images are thus acquired at 25 Hz for each of the two sets of lines of a line on two. To obtain complete images filling all the frames, the images of each line are processed to be interpolated by calculation between two successive taps and assigned to them, for the unlit lines, the value calculated by the interpolation. It goes without saying that the images could be complete as soon as they are acquired.

D'autres procédés d'acquisition des images peuvent être envisagés. Par exemple, l'obturateur de la caméra 6 peut rester ouvert, le flash n'étant allumé que lors des passages de l'aube 2 tous les "n" tours. La vidéo comporterait alors des périodes noires, ou juste avec la lumière ambiante, et des périodes éclairées. Par ailleurs, une lumière constante pourrait éclairer les aubes 2, l'obturateur de la caméra 6 étant réglé pour n'être ouvert que tous les "n" tours de l'aube 2. Toutefois, la rapidité d'ouverture et de fermeture de l'obturateur de la caméra 6 étant inférieure à celle de l'allumage et l'extinction du stroboscope 10, il vaut mieux que la précision de capture de l'aube 2 soit assurée par le stroboscope 10.Other image acquisition methods can be envisaged. For example, the shutter of the camera 6 can remain open, the flash being lit only during the passage of the blade 2 every "n" turns. The video would then have black periods, or just with ambient light, and illuminated periods. Furthermore, a constant light could illuminate the blades 2, the shutter of the camera 6 being set to be open only every "n" turns of the blade 2. However, the speed of opening and closing of the shutter of the camera 6 being smaller than that of the ignition and the extinction of the strobe 10, it is better that the capture accuracy of the blade 2 is provided by the strobe 10.

Les images acquises par la caméra 6 sont traitées dans les moyens de traitement 8 situés dans l'ordinateur 7. Une fois les images traitées pour être complètes sur toutes leurs lignes, elles sont analysées. Il est possible que des lumières parasites, autres que la lumière de l'image du sommet de l'aube 2, apparaissent sur les images. Ces lumières parasites peuvent notamment provenir de réflexions diverses dans l'enceinte contenant les aubes 2, par exemple sur les parois des aubes 2 ou sur leur pied, de réflexions liées au couplage entre les fibres optiques 11 du stroboscope 10 et la sonde 5. Ces lumières parasites sont filtrées dans le dispositif de traitement 8, soit par seuillage lumineux de l'image, soit par suppression de portions de l'image comportant des lumières parasites identifiables, dont on sait a priori qu'elles ne peuvent correspondre au sommet de l'aube 2. Le bruit du signal, notamment lié à la lumière ambiante, est également supprimé à l'aide d'un filtre passe-bas. On extrait ainsi l'image du sommet de l'aube 2 de l'image. On recherche ensuite le point le plus proche du bord de l'image, afin de tenir compte d'éventuelles désalignements de la sonde 5 avec l'aube 2, par scrutation de l'image de bas en haut par exemple, afin d'obtenir la position du sommet d'aube 2.The images acquired by the camera 6 are processed in the processing means 8 located in the computer 7. Once the processed images to be complete on all their lines, they are analyzed. It is possible that stray lights, other than the image light from the top of the blade 2, appear on the images. These parasitic lights may in particular come from various reflections in the enclosure containing the blades 2, for example on the walls of the blades 2 or on their feet, reflections related to the coupling between the optical fibers 11 of the strobe 10 and the probe 5. These parasitic lights are filtered in the processing device 8, either by luminous thresholding of the image, or by deleting portions of the image having identifiable parasitic lights, which we know a priori that they can not correspond to the apex of the image. 2. The signal noise, especially related to ambient light, is also suppressed using a low-pass filter. This extracts the image from the top of the blade 2 of the image. Next, the closest point to the edge of the image is sought to take account of any misalignments of the probe 5 with the blade 2, for example by scanning the image from the bottom upwards in order to obtain the position of the dawn top 2.

Les images sont au format numérique et sont donc constituées de pixels. L'objectif du procédé d'utilisation du dispositif 1 étant la mesure du déplacement axial du sommet des aubes 2, les positions des aubes 2 aux divers régimes de fonctionnement du turboréacteur sont comparées à leur position calculée à l'arrêt ; il faut ensuite convertir ces différences de positions de pixels en distance. A cet effet, on pourra avoir préalablement effectué l'acquisition d'images d'un objet témoin, de dimensions connues, placé à une distance de la sonde 5 sensiblement égale à celle à laquelle est placé le sommet des aubes 2, afin de calculer un facteur de conversion de pixels en millimètres, par exemple. A titre d'exemple, les déplacements axiaux des aubes représentent, pour une soufflante, 10 à 20 mm, pour un compresseur haute pression d'un turboréacteur à double flux, 5 à 10 mm, pour un compresseur basse pression, 1 à 5 mm.The images are in digital format and therefore consist of pixels. The objective of the method of use of the device 1 being the measurement of the axial displacement of the top of the blades 2, the positions of the blades 2 at the various operating speeds of the turbojet engine are compared to their calculated position when stopped; these differences in pixel positions must then be converted into distances. For this purpose, it may be previously carried out the acquisition of images of a control object, of known dimensions, placed at a distance from the probe 5 substantially equal to that at which is placed the top of the blades 2, in order to calculate a conversion factor of pixels in millimeters, for example. By way of example, the axial displacements of the blades represent, for a blower, 10 to 20 mm, for a high-pressure compressor of a turbofan engine, 5 to 10 mm, for a low-pressure compressor, 1 to 5 mm .

Grâce au dispositif de l'invention et à son procédé d'utilisation, on peut donc mesurer en temps réel, sur un turboréacteur en fonctionnement lors d'essais au sol, les déplacements axiaux du sommet des aubes à l'aide de moyens d'acquisition d'images déportés par rapport aux moyens de prise de vues, auxquels ils sont reliés par des moyens de conduction des images. La fréquence de prise d'images du dispositif est adaptée en temps réel au régime de fonctionnement du turboréacteur.Thanks to the device of the invention and to its method of use, it is therefore possible to measure, in real time, on a turbojet engine operating during ground tests, the axial displacements of the top of the blades by means of acquisition of deported images with respect to the shooting means, to which they are connected by means means of conduction of images. The imaging frequency of the device is adapted in real time to the operating speed of the turbojet engine.

Les deux formes de réalisation préférées de l'invention vont maintenant être décrites, en relation avec les figures 2 et 3.The two preferred embodiments of the invention will now be described, in connection with FIGS. 2 and 3.

En référence à la figure 2, selon une première forme de réalisation, la sonde du dispositif 1 est un fibroscope 5a. Il comporte un conduit optique souple 15, comprenant une pluralité de fibres optiques en parallèle, ici au nombre de 10 000. Le conduit optique 15 est collé à une ferrule 16, logée dans un manchon 17 de raccord au carter 4 du compresseur. Le manchon 17 comporte une portion de tête 18, de raccord des fibres 11 reliées au stroboscope 10, dans laquelle est logée la ferrule 16, qui se prolonge par une portion tubulaire creuse 19 ménageant avec elle un épaulement 20 d'appui sur le carter 4. La ferrule 16 peut également s'étendre dans la portion tubulaire 19. Cette dernière comporte un filetage externe 21, qui est vissé dans un alésage correspondant du carter 4, assurant ainsi l'étanchéité de l'ensemble. La ferrule 16 débouche dans le conduit interne de la portion tubulaire 19, qui se prolonge par l'alésage 9 du carter 4, et se situe donc au droit du lieu de passage du bord d'attaque du sommet des aubes 2, dont elle prend des images. Les fibres 11 reliées au stroboscope 10, non représentées, s'étendent ici en arc de cercle partiel autour de la ferrule 16. Le fibroscope 5a est relié directement à la caméra 6 par son conduit optique 15.With reference to FIG. 2, according to a first embodiment, the probe of the device 1 is a fiberscope 5a. It comprises a flexible optical conduit 15, comprising a plurality of optical fibers in parallel, in this case numbering 10,000. The optical conduit 15 is bonded to a ferrule 16, housed in a sleeve 17 for coupling to the casing 4 of the compressor. The sleeve 17 comprises a head portion 18 for connecting the fibers 11 connected to the stroboscope 10, in which the ferrule 16 is housed, which is extended by a hollow tubular portion 19 forming with it a bearing shoulder 20 on the housing 4 The ferrule 16 may also extend in the tubular portion 19. The latter has an external thread 21, which is screwed into a corresponding bore of the casing 4, thereby sealing the assembly. The ferrule 16 opens into the inner duct of the tubular portion 19, which extends through the bore 9 of the casing 4, and is therefore located at the place of passage of the leading edge of the top of the blades 2, which it takes images. The fibers 11 connected to the stroboscope 10, not shown, here extend in a partial arc around the ferrule 16. The fiberscope 5a is connected directly to the camera 6 by its optical conduit 15.

Du fait de la souplesse de ces moyens de conduction d'images, à savoir le conduit optique 15, le fibroscope 5a peut être monté dans des zones très difficiles d'accès et encombrées. Les images obtenues sont diaphragmées par la pupille d'entrée circulaire de la lumière de la ferrule 16, formant moyens de prise de vues. En outre, les images sont discrétisées du fait de la juxtaposition des fibres optiques.Due to the flexibility of these image conduction means, namely the optical conduit 15, the fiberscope 5a can be mounted in very difficult to access and congested areas. The images obtained are diaphragmed by the circular entrance pupil of the light of the ferrule 16, forming means of shooting. In addition, the images are discretized because of the juxtaposition of the optical fibers.

En référence à la figure 3, selon une deuxième forme de réalisation, la sonde du dispositif 1 est un endoscope 5b. Il comporte un conduit optique rigide 22. Ce conduit 22 comprend typiquement un conduit métallique, dans lequel sont disposées en série des lentilles, distantes les unes des autres de leur longueur focale, non représentées. Le conduit optique rigide 22 est logé dans un manchon 23 de raccord au carter 4 du compresseur. Le manchon 23 comporte une portion de tête 24, de raccord des fibres 11 reliées au stroboscope 10, et une portion tubulaire creuse 25. La portion tubulaire 25 comporte un filetage externe 26, qui est vissé dans un alésage correspondant du carter 4, assurant ainsi l'étanchéité de l'ensemble. Le conduit optique 22 débouche dans le conduit interne de la portion tubulaire 25, qui se prolonge par l'alésage 9 du carter 4, et se situe donc au droit du lieu de passage du bord d'attaque du sommet des aubes 2, dont elle prend les images. Les fibres 11 reliées au stroboscope 10, non représentées, s'étendent ici en arc de cercle partiel autour du conduit optique 22.With reference to FIG. 3, according to a second embodiment, the probe of the device 1 is an endoscope 5b. It comprises a rigid optical conduit 22. This conduit 22 typically comprises a metal conduit, in which are arranged in series lenses, spaced apart from each other by their focal length, not shown. The rigid optical conduit 22 is housed in a sleeve 23 of connection to the casing 4 of the compressor. The sleeve 23 comprises a head portion 24, connecting the fibers 11 connected to the stroboscope 10, and a hollow tubular portion 25. The tubular portion 25 has an external thread 26, which is screwed into a corresponding bore of the housing 4, thus ensuring the tightness of the whole. The optical duct 22 opens into the internal duct of the tubular portion 25, which is extended by the bore 9 of the casing 4, and is therefore at the right of the place of passage of the leading edge of the top of the blades 2, which she takes the images. The fibers 11 connected to the stroboscope 10, not shown, here extend in a partial arc around the optical duct 22.

La caméra 6 peut être montée à l'extrémité externe du conduit optique 22, si l'encombrement le permet, par un raccord. Le conduit optique 22 assure donc une fonction de prise de vues, par son extrémité interne, et une fonction de conduction d'images jusqu'à la caméra 6. Le conduit optique 22 peut aussi être relié à d'autres moyens de conduction des images, typiquement des fibres optiques, reliées à leur tour à la caméra 6.The camera 6 can be mounted at the outer end of the optical conduit 22, if space permits, by a connector. The optical conduit 22 thus provides a shooting function, by its internal end, and an image conduction function to the camera 6. The optical conduit 22 can also be connected to other means of conduction images typically optical fibers, in turn connected to the camera 6.

Du fait de la rigidité de ses moyens de prise de vues et de conduction d'images, à savoir le conduit optique 22, l'endoscope 5b est légèrement plus contraignant à monter que le fibroscope 5a. En revanche, les images qu'il prend ne sont pas discrétisées comme pour le fibroscope 5a, l'éclairage pouvant être meilleur, ce qui fournit des images de meilleure résolution. Le champ de l'objet filmé, s'il est plus précis, est en revanche plus petit, du fait du grossissement par les lentilles ; ce grossissement implique par ailleurs que la vitesse apparente des aubes devant l'endoscope 5b est d'autant plus grande, ce qui nécessite une meilleure précision sur la prise de vues afin que les images ne soient pas trop floues et ne comportent pas de traînée ou trace trop importante du fait du mouvement des aubes.Because of the rigidity of its imaging means and image conduction, namely the optical conduit 22, the endoscope 5b is slightly more restrictive to mount than the fiberscope 5a. On the other hand, the images that it takes are not discretized as for the fiberscope 5a, the lighting being able to be better, which provides images of better resolution. The field of the filmed object, if it is more precise, is on the other hand smaller, because of the magnification by the lenses; this magnification also implies that the apparent speed of the blades in front of the endoscope 5b is all the greater, which requires a better precision in the shooting so that the images are not too fuzzy and do not involve drag or trace too important because of the movement of the blades.

Claims (10)

Dispositif de mesure du déplacement axial des aubes (2) d'un rotor d'une turbomachine, pour des essais au sol, caractérisé par le fait qu'il comprend des moyens (5) de prise de vues et de conduction d'images agencés pour être implantés au droit des aubes (2) et reliés à des moyens (6) déportés d'acquisition des images.Device for measuring the axial displacement of the blades (2) of a rotor of a turbomachine, for ground tests, characterized in that it comprises means (5) for shooting and conduction of images arranged to be implanted at the right of the blades (2) and connected to means (6) remote image acquisition. Dispositif selon la revendication 1, comprenant des moyens (10) de génération de lumière.Device according to claim 1, comprising means (10) for generating light. Dispositif selon la revendication 2, comprenant des moyens (12) de synchronisation des moyens (10) de génération de lumière et des moyens (6) d'acquisition des images.Device according to claim 2, comprising means (12) for synchronizing the means (10) for generating light and means (6) for acquiring images. Dispositif selon la revendication 3, dans lequel les moyens (12) d e synchronisation sont commandés par la fréquence de rotation des aubes (2).Device according to claim 3, wherein the means (12) of synchronization are controlled by the rotation frequency of the blades (2). Dispositif selon l'une des revendications 1 à 4, comprenant des moyens (8) de traitement des images reliés aux moyens (6) d'acquisition des images.Device according to one of claims 1 to 4, comprising means (8) for processing images connected to the means (6) for acquiring images. Dispositif selon l'une des revendications 1 à 5, dans lequel les moyens (5) de prise de vues et de conduction d'images comprennent un fibroscope (5a).Device according to one of claims 1 to 5, wherein the means (5) for shooting and image conduction comprise a fiberscope (5a). Dispositif selon l'une des revendications 1 à 5, dans lequel les moyens (5) de prise de vues et de conduction d'images comprennent un endoscope (5b).Device according to one of claims 1 to 5, wherein the means (5) for shooting and image conduction comprises an endoscope (5b). Dispositif selon l'une des revendications 1 à 7, dans lequel les moyens (6) d'acquisition des images comprennent une caméra (6) du type CCD.Device according to one of claims 1 to 7, wherein the means (6) for acquiring images comprises a camera (6) of the CCD type. Procédé de mesure du déplacement axial des aubes (2) d'un rotor d'une turbomachine, pour des essais au sol, avec le dispositif de la revendication 4, dans lequel les moyens (12) de synchronisation émettent un signal de déclenchement des moyens (10) de génération de lumière et des moyens (6) d'acquisition des images à chaque passage d'une aube particulière tous les "n" tours.A method for measuring the axial displacement of the blades (2) of a rotor of a turbomachine, for ground tests, with the device of claim 4, wherein the means (12) of synchronization emit a trigger signal means (10) for generating light and means (6) for acquiring images at each passage of a particular blade every "n" turns. Procédé de mesure selon la revendication 9, dans lequel on mesure préalablement la position des aubes (2) à l'arrêt de la turbomachine.Measuring method according to claim 9, wherein the position of the blades (2) is previously measured at the stopping of the turbomachine.
EP05109335A 2004-10-12 2005-10-07 Apparatus and method of using the apparatus for measuring the axial displacement of the tips of the blades of a turbomachine in ground tests Withdrawn EP1647801A2 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR0452343A FR2876444B1 (en) 2004-10-12 2004-10-12 DEVICE FOR MEASURING THE TURBOMACHINE'S AXIS TILT AXIAL MOTION FOR TESTS ON THE GROUND AND METHOD OF USING THE DEVICE

Publications (1)

Publication Number Publication Date
EP1647801A2 true EP1647801A2 (en) 2006-04-19

Family

ID=34950670

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05109335A Withdrawn EP1647801A2 (en) 2004-10-12 2005-10-07 Apparatus and method of using the apparatus for measuring the axial displacement of the tips of the blades of a turbomachine in ground tests

Country Status (4)

Country Link
US (1) US20060088414A1 (en)
EP (1) EP1647801A2 (en)
JP (1) JP2006125393A (en)
FR (1) FR2876444B1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103323461A (en) * 2013-06-14 2013-09-25 上海大学 On-line detection method for movement of non-contact type wind driven generator blade
FR3079031A1 (en) * 2018-03-16 2019-09-20 Safran Aircraft Engines IMPROVED TEST DEVICE FOR TURBOMACHINE

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7918642B2 (en) * 2007-01-10 2011-04-05 United Technologies Corporation Instrument port seal for RF measurement
ES2320835B1 (en) * 2007-05-03 2010-01-29 Danobat, S. Coop MEASUREMENT DEVICE OF THE PARAMETERS OF A ROTOR OF ALABES AND MEASUREMENT PROCEDURE WITH SUCH DEVICE.
GB201004559D0 (en) * 2010-03-19 2010-05-05 Rolls Royce Plc Rotating blade analysis
US9488467B2 (en) 2010-10-28 2016-11-08 General Electric Company System and method for monitoring in real time, a gap between portions in a machine
KR101304324B1 (en) * 2012-04-06 2013-09-11 박찬홍 Turbine measurement method using image measurement technology
US8687206B2 (en) 2012-05-29 2014-04-01 United Technologies Corporation Optical detection of airfoil axial position with NSMS
FR3094397B1 (en) 2019-03-25 2021-05-14 Safran Aircraft Engines DEVICE AND METHOD FOR NON-DESTRUCTIVE CONTROL OF A ROTOR OF A CONTRAROTARY TURBINE OF AN AIRCRAFT TURBOMACHINE
DE102019113154A1 (en) * 2019-05-17 2020-11-19 Schenck Rotec Gmbh Method and device for measuring strain on a body subject to centrifugal force
CN114563148B (en) * 2022-03-04 2023-09-22 中国航发沈阳发动机研究所 Rigidity test structure of aero-engine inlet guide vane angle adjusting mechanism

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3327584A (en) * 1963-09-09 1967-06-27 Mechanical Tech Inc Fiber optic proximity probe
US3856410A (en) * 1972-11-27 1974-12-24 Tracker M Corp Method and apparatus for testing bladed rotors
US3917432A (en) * 1974-11-13 1975-11-04 Gen Electric Borescope support apparatus
US4049644A (en) * 1976-06-23 1977-09-20 Wennerstrom Arthur J Device for measuring tip deflection of rotating blades
US4180329A (en) * 1978-03-23 1979-12-25 The United States Of America As Represented By The Secretary Of The Air Force Single blade proximity probe
US4326804A (en) * 1980-02-11 1982-04-27 General Electric Company Apparatus and method for optical clearance determination
KR840006854A (en) * 1982-11-10 1984-12-03 원본미기재 Position detector
US4572663A (en) * 1983-12-22 1986-02-25 Elliott Turbomachinery Co., Inc. Method and apparatus for selectively illuminating a particular blade in a turbomachine
FR2641373B1 (en) * 1988-12-30 1993-01-15 Aerospatiale INSTALLATION FOR MEASURING DEFORMATIONS OF AN OBJECT SUBJECT TO CONSTRAINTS
US5349850A (en) * 1992-11-19 1994-09-27 General Electric Company Instrumentation light probe holder
US6037581A (en) * 1996-01-15 2000-03-14 Siemens Aktiengesellschaft Device for recording a change in position at a turbine configuration
US6785635B2 (en) * 1999-08-02 2004-08-31 Hood Technology Corporation Apparatus and method for predicting failures of spinning disks in turbo-machinery
US6727994B2 (en) * 2002-06-26 2004-04-27 Taiwan Semiconductor Manufacturing Co., Ltd Z-axis monitoring apparatus for robot blade
US7106421B2 (en) * 2003-04-04 2006-09-12 Omron Corporation Method of adjusting axial direction of monitoring apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103323461A (en) * 2013-06-14 2013-09-25 上海大学 On-line detection method for movement of non-contact type wind driven generator blade
CN103323461B (en) * 2013-06-14 2015-05-27 上海大学 On-line detection method for movement of non-contact type wind driven generator blade
FR3079031A1 (en) * 2018-03-16 2019-09-20 Safran Aircraft Engines IMPROVED TEST DEVICE FOR TURBOMACHINE

Also Published As

Publication number Publication date
US20060088414A1 (en) 2006-04-27
JP2006125393A (en) 2006-05-18
FR2876444A1 (en) 2006-04-14
FR2876444B1 (en) 2007-06-22

Similar Documents

Publication Publication Date Title
EP1647801A2 (en) Apparatus and method of using the apparatus for measuring the axial displacement of the tips of the blades of a turbomachine in ground tests
EP0351257B1 (en) Apparatus for the optical profile control of a tube or bore
FR2475719A1 (en) OPTICAL SYSTEM AND METHOD FOR DETERMINING THE GAME BETWEEN TWO ELEMENTS
EP2681537B1 (en) Device for searching for defects on parts by endoscopy
EP1542053B1 (en) Measuring device for video-endoscopic probe
EP2741310B1 (en) System for detecting cathodoluminescence optimising the collection of the signal, the spectral resolution and the preservation of brightness, and microscope implementing such a system
FR2969891A1 (en) ONLINE MONITORING SYSTEM OF A ROTARY MACHINE
FR2463926A1 (en) MEASURING DEVICE FOR CRACK PROPAGATION
CA2568021A1 (en) Device to measure cracks in piping
FR2579883A1 (en)
EP2577706B1 (en) Flexible cathodoluminescence detection system and microscope employing such a system
EP1494060A1 (en) Apparatus for searching and detecting flaws in parts by endoscopy
FR2969283A1 (en) SYSTEM FOR DETECTING SCALE IN A TURBINE ENGINE
EP1183518B1 (en) Device for determining the values of at least one parameter of particles, in particular water droplets
EP0222635A1 (en) Device for remotely monitoring defects on the inner surface of a deep cavity
FR3088720A1 (en) Probe suitable for measuring the composition of an oxidizing gas
EP1581833A1 (en) Miniature confocal optical head with integrated scanning and confocal imaging system using same
EP2667151A1 (en) Chromatic altimetry converter
EP0997722B1 (en) Procedure and instrument for controlling the connection of the bars in honeycomb panel cells
EP0619482B1 (en) Apparatus for controlling the continuity of a joint-forming adhesive ribbon
US20100033707A1 (en) Device and method for three-dimensional flow measurement
FR2909182A1 (en) Retroreflecting object e.g. eye, detecting method, involves forming two set of images of scene through respective filters whose bandwidths are adjusted on wavelengths during object illumination, respectively, and forming third set of image
EP0668493B1 (en) Procedure and device for testing of honeycomb structures using optical fibres
FR2568026A1 (en) HOLOGRAPHIC CAMERA AND NON-DESTRUCTIVE CONTROL DEVICE USING SUCH A CAMERA
EP0389727A1 (en) Arrangement for measuring the deformation of an object put under stress

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20051007

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA HR MK YU

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

18W Application withdrawn

Effective date: 20060411