Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
  • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
• • 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
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
  • G01B7/14—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring distance or clearance between spaced objects or spaced apertures
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
  • G01H1/00—Measuring characteristics of vibrations in solids by using direct conduction to the detector
  • G01H1/003—Measuring characteristics of vibrations in solids by using direct conduction to the detector of rotating machines
  • G01H1/006—Measuring characteristics of vibrations in solids by using direct conduction to the detector of rotating machines of the rotor of turbo machines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2250/00—Geometry
  • F05D2250/30—Arrangement of components
  • F05D2250/31—Arrangement of components according to the direction of their main axis or their axis of rotation
  • F05D2250/314—Arrangement of components according to the direction of their main axis or their axis of rotation the axes being inclined in relation to each other
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2270/00—Control
  • F05D2270/80—Devices generating input signals, e.g. transducers, sensors, cameras or strain gauges
  • F05D2270/821—Displacement measuring means, e.g. inductive

Definitions

• the present invention relates to a device and a method for measuring the passage times of the blade tips in a stage of a turbomachine such as an airplane turbojet or turboprop.
• a turbomachine with a double flow comprises a fan at the outlet of which the flow of air is divided into a primary air flow circulating inside a turbojet engine in a compressor, a combustion chamber and a turbine and a secondary air flow circulating around the turbojet engine.
• the compressor comprises several rows of moving blades arranged alternately with rows of stationary blades and surrounded by a housing.
• a coating of abradable material is carried by the inner surface of the fan casing and arranged at the blades of the fan.
• the integration of sensors is achieved by the formation of orifices in the casing at the blades, which weakens the housing and forms cavities at the radially outer ends of the vanes which generate noise because of the passage of blades to great speed.
• Another drawback stems from the fact that it is difficult to know precisely the relative axial positioning of the sensors with respect to the blade tips. This difficulty stems from the accumulation of manufacturing tolerances of the wheel and the fastening elements of the wheel on its rotor itself positioned axially relative to the housing carrying the sensors.
• the aerodynamic, thermal and mechanical stresses of the operating turbomachine can also affect the relative axial positioning of the blade tips with respect to the electrodes.
• the invention aims in particular to provide a simple, economical and effective solution to these various problems.
• a turbomachine stage comprising a capacitive sensor mounted on a casing at the right of the path of passage of the blade tips of a mobile wheel for measuring the passage times of the blade tips, characterized in that the sensor comprises at least one elongate electrode fixed on the inner face of the housing and oriented obliquely with respect to the trajectory of the blade tips so as to extend along the axis of rotation of the wheel. through trajectories at least leading edges or trailing edges of the blades, and in that the downstream end of the electrode is offset circumferentially with respect to its upstream end in the same direction as the trailing edges of the vanes compared to the leading edges of the blades.
• the combination according to the invention of a capacitive sensor with an elongated electrode and its positioning across the trajectory at least the leading edges or trailing edges of the blade tips makes it possible to have information on the time of passing a predetermined zone of the blade, namely the leading or trailing edges of the blades, and this regardless of the relative axial positioning of the tips of the blades relative to the sensor.
• the circumferential offset of the downstream end of the electrode with respect to its upstream end in the same direction as the trailing edges of the vanes with respect to the leading edges of the blades ensures that only one blade apex at a time is positioned in line with the electrode, i.e., aligned in a radial direction with the electrode.
• the signals obtained at the output of the sensor are relative to a blade tip only, which facilitates their interpretation.
• the electrode is dimensioned and positioned so as to extend across the trajectories of the leading edges and vanishing edges of the blades, which makes it possible to measure with a single electrode the passage times of the leading edges. and trailing edges of the vanes.
• the electrode extends along an axis forming a non-zero angle with a plane passing through the leading edge and the trailing edge of a blade.
• the leading edge will pass first in front of the electrode and then the rest of the blade tip will pass in front of the electrode. electrode and the trailing edge will be detected temporally last.
• a second elongate electrode is fixed on the inner face of the housing and oriented so as to form a non-zero angle with the first electrode.
• This configuration makes it possible, with the aid of the leading edge and the trailing edge time of a given blade to reach the right of the first electrode, and of the leading edge and the trailing edge of this first electrode. blade given to the right of the second electrode, coupled to the speed of rotation of the blades, to know the axial position of the leading and trailing edges of the blades relative to the housing.
• means are provided for determining the profile of clearance between a blade tip and the housing, from the sensor output signal and calibration values.
• the invention also relates to a turbomachine, such as a turbojet engine or a turboprop engine, comprising at least one stage such as as previously described.
• the sensor or sensors are covered by an abradable layer carried by the inner face of the housing to the right of the blade tips, which avoids making passage openings for the sensors as in the prior art, and allows to protect capacitive sensors from moisture.
• the invention also relates to a method for measuring the passage times of the blade tips in a turbomachine, characterized in that it consists of:
• this electrode being oriented obliquely with respect to the trajectory of the vertices of the vane so as to extend along the axis of rotation of the wheel across the trajectories of at least the leading edges or trailing edges of the vanes, the downstream end of the electrode being circumferentially offset by at its upstream end in the same direction as the trailing edges of the vanes with respect to the leading edges of the vanes,
• the method consists in measuring the variations in the difference in the passage time of the blades between the leading edges and the trailing edges of the blades over time and in deducing therefrom information relating to twisting or twisting blades around their longitudinal axes.
• the method consists of:
• FIG. 1 is a schematic half-view in axial section of a fan of a turbojet engine
• FIG. 2 is a schematic axial sectional view of a sensor carried by the fan casing of Figure 1, in the prior art;
• FIG. 3 is a schematic representation of a deformation of the blade by twisting or twisting along a longitudinal axis passing through the foot and the blade tip;
• FIG. 4 is a graph of the time detection of the passage of blade tips to the right of a sensor according to the prior art
• FIG. 5 is a schematic top view of two consecutive blade tips and a slender sensor according to the invention.
• FIG. 6 is a schematic representation of the displacement of a blade tip facing an elongate electrode according to the invention
• FIG. 7 is a graph of the variation of electrical capacitance measured by the elongated electrode as a function of time during the passage of the blades facing the electrode of FIG. 5;
• FIG. 8 is a graph showing the evolution of the capacity electrical in a different arrangement of the elongate electrode with respect to the blade tips;
• FIG. 9 is a schematic representation of a deformation of the blade by twisting or twisting along a longitudinal axis passing through the foot and the blade tip and an elongate electrode according to the invention.
• FIG. 10 is a schematic top view of two elongate electrodes according to the invention and a blade tip;
• FIG. 1 shows a fan 10 of a shaft turbomachine 12, comprising a wheel formed of a disc 14 carrying at its periphery a plurality of blades 16 whose feet are engaged in grooves of the disc 14 and whose blades 18 extend radially outwards in the direction of a fan casing 20 carrying a nacelle 22 externally surrounding the vanes 16.
• the blower wheel is rotated about the axis 12 the turbomachine by a shaft 24 fixed by bolts 26 to a frustoconical wall 28 integral with the fan wheel.
• the shaft 24 is supported and guided by a bearing 30 which is carried by the upstream end of an annular support 32 attached downstream to an intermediate casing (not shown) disposed downstream of a low-pressure compressor 34 whose rotor 36 is secured to the blower wheel via a connecting wall 38.
• the fan casing 20 comprises on an inner face a coating of abradable material 40 disposed at the right of the fan blades 16 and intended to wear during contact with the radially outer ends of the blades 16. This layer of abradable material 40 reduces the clearance between the tops of the blades 16 and the fan casing 20 and thus optimize the performance of the turbomachine.
• the low-pressure compressor 34 comprises an alternation of fixed vanes 42 carried by an outer casing 44 and movable wheels 46 carried by the rotor 36.
• Each movable wheel 46 comprises a plurality blades regularly distributed around the axis 12 of the turbomachine and is surrounded externally by a layer 48 of abradable material carried by the inner surface of the casing 44 of the low pressure compressor.
• This housing 20 comprises bosses 50 formed on its outer surface and circumferentially spaced apart from each other.
• Each boss 50 comprises an orifice 52 opening inside the housing 20 in the flow passage of the air flow and contains a sensor 54 of substantially cylindrical shape, connected by a cable to the processing means 56.
• Each sensor 54 comprises an annular base 57 at its radially outer end.
• An annular wedge 58 is interposed between the base 57 and the outer surface of the boss 50. This wedge 58 provides adjustment of the insertion level of the sensor inside the orifice.
• Each sensor 54 is inserted from outside the housing into an orifice 52 and the thickness of the spacer 58 is such that the active face of the sensor is recessed within the orifice 52 relative to at the outlet of the orifice in the air flow vein.
• the layer of abradable material 40 covers the inner surface of the casing with the exception of outlets 52 orifices. A cavity 60 is thus formed between the radially outer ends of the vanes 18 and the active face or electrode 62 of each sensor 54.
• FIG. 3 diagrammatically represents the top 64 of a blade in undeformed position D 0 and two deformation positions Di, D 2 by twisting the blade around a longitudinal axis 65 extending between its foot and its apex.
• the blade comprises a leading edge 66 and a trailing edge 68.
• Three possible axial positions A, B, C of a sensor relative to at dawn For the first position A, at the passage of the blade in the state of strain Di in front of the electrode, the sensor records a variation of the electrical capacitance (in arbitrary unit, FIG. 4) as a function of time. This curve passes through a maximum amplitude corresponding to a time representing the passage time of the zone Ai of the blade tip 64 to the right of the electrode.
• the invention therefore proposes to solve this drawback as well as those mentioned above by means of at least one capacitive sensor comprising a rectilinear electrode 70 fixed on the internal face of the casing.
• the electrode 70 extends along the axis of rotation 72 and across the path of the blades so that at least the leading edges 66 or the trailing edges 68 of the blades pass to the right of the blade. electrode 70 carried by the housing.
• the electrode 70 is dimensioned and positioned on the housing so that the detection of the leading edges or trailing edges can be achieved regardless of the state of deformation of the blade. In practice, to ensure this detection, the sensor must extend sufficiently upstream or downstream of the leading edge or the trailing edge, respectively to ensure its detection by the electrode (see Figure 9 representing several deformation states). of a dawn).
• the electrode 70 extends both across the trajectories of the leading edges and the trailing edges of the blades. With such an arrangement, the electrode can detect both the passage of leading edges 66 and trailing edges 68 of the blades.
• the downstream end 74 of the electrode 70 is shifted circumferentially with respect to its upstream end 76 in the same direction as the trailing edges 68 of the blades with respect to the leading edges 66 of the blades.
• the axis 77 of the rectilinear electrode 70 forms a non-zero angle with the planes 78, 83 containing the leading edge 66 and the trailing edge 68 of blades 79, 81.
• the axis 77 intercepts the plane 78 upstream of the leading edge 66 of the blade 79 and intercepts the plane 83 downstream of the trailing edge 68 of the blade 81. In this way, it can be ensured that the leading edge 66 passes first in front of the rectilinear electrode 70 and that the remainder of the blade tip passes in front of the electrode to the trailing edge 68.
• FIG. 6 represents three positions Pi, P 2 and P 3 of the rectilinear electrode with respect to a blade vertex 80. For ease of representation, three positions of the same electrode 70 are represented, although it is blade which shifts with respect to the electrode 70.
• the first position Pi of the electrode corresponds to that where the leading edge 66 of the blade is positioned at the right of the rectilinear electrode 70 which corresponds to the instant t x in FIG. 7.
• the second position P 2 of the electrode corresponds to that where the median portion 82 of the blade tip 80 is positioned to the right of the electrode 70, which corresponds to the instant t 2 in Figure 7.
• the third position P 3 of the electrode 70 corresponds to that where the trailing edge 68 of the blade is positioned at the right of the rectilinear electrode 70, which corresponds to the instant t 3 in FIG. 7.
• a calibration of the amplitude of the electrical capacitance is performed as a function of the distance between the blade tip 80 and the electrode 70 and as a function of the position of the electrode 70 to the right of the blade tip 80.
• the leading edge 66 of the blade 80 is positioned at the right of the electrode 70 and several measurements of the electrical capacitance of the electrode 70 are made by bringing the blade tip 80 closer to the electrode 70. This operation is repeated for a plurality of successive positions P, from the electrode 70 to the right from the blade tip 80 to the positioning P 3 of the electrode 70 to the right of the trailing edge 68 of the blade 80.
• a calibration curve of the amplitude is obtained. of the electrical capacitance as a function of the distance from the electrode 70 to the right of the blade tip 80 for each position of the blade tip 80 with respect to the electrode 70, which makes it possible to deduce the variations of the game along the top of a dawn 80.
• the invention thus makes it possible to determine the game y. between the top of a blade and the housing from the upstream end of the blade tip 80 joining the leading edge 66 to the downstream end of the blade tip 80 joining the trailing edge 68.
• the electrode 70 is inclined relative to the axis 72 so that the vertex 80 of a single blade can be positioned at the right of the electrode at each moment. This type of editing simplifies the interpretation of signals electric obtained at the output of the sensor.
• the leading edge 66 of a first blade and the trailing edge 68 of a second adjacent blade would be detected simultaneously by the electrode. which would induce an increase in the electrical capacitance measured by the sensor.
• the first between t x and t 2 corresponds to the passage of a first blade to the electrode
• the second level between t 2 and t 3 corresponds to simultaneous detection of the top of the first blade and the top of the second blade
• the third step between t 3 and t 4 corresponding to the detection of the top of the second blade alone.
• Figure 9 is a view similar to Figure 3 of the prior art and on which was added a rectilinear electrode 84 oriented along the axis of rotation 72 of the blades.
• the blade When the blade is in its undistorted state D 0 , it passes to the right of the electrode 84 between times t x and t 2 . In the state of strain Di, it passes to the right of the electrode between times t and t 2 .
• variation between the time differences t x - t 2 , t [- t 2 and i [- t 2 gives information on the twisting or twisting of the blade along its longitudinal axis 65.
• a second rectilinear electrode 86 is fixed on the internal face of the casing and oriented so as to form a non-zero angle with the first electrode 84 and with a plane 78 passing through the leading edge and the trailing edge of dawn ( Figure 10).
• this calculation method assumes that the amplitude of deformation of the blade is negligible compared to the arc distance traveled by the dawn, which in practice is generally the case.
• digital processing such as for example an average of times t 3 - t l and t 4 - t 2 on several turns.
• the electrodes 70, 84, 86, 90, 82 are of rectilinear shape.
• the electrodes can have an elongated shape without being straight.
• the electrodes may have a curved shape adapted to extend along the axis of rotation 72 of the wheel across the trajectories at least leading edges 66 or trailing edges 66 of the vanes.
• Other electrode shapes are also possible such as, for example, a zig-zag shape comprising a succession of curved parts or a succession of rectilinear parts arranged end to end.
• turbomachine it is however understood that the invention is applicable to any subset of a machine comprising a casing and a paddle wheel rotating inside the housing which carries at least an electrode arranged and sized as described above.
• the invention is applicable to a turbomachine fan as previously described and shown in FIG.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

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• 2011
  • 2011-07-01 FR FR1155983A patent/FR2977316B1/fr active Active
• 2012
  • 2012-06-27 RU RU2014103480/28A patent/RU2593427C2/ru not_active IP Right Cessation
  • 2012-06-27 WO PCT/FR2012/051478 patent/WO2013004951A2/fr active Application Filing
  • 2012-06-27 CN CN201280031373.4A patent/CN103620355B/zh not_active Expired - Fee Related
  • 2012-06-27 EP EP12738537.5A patent/EP2726829A2/de not_active Withdrawn
  • 2012-06-27 BR BR112013033935A patent/BR112013033935A2/pt not_active Application Discontinuation
  • 2012-06-27 CA CA2839815A patent/CA2839815A1/fr not_active Abandoned
  • 2012-06-27 US US14/130,382 patent/US20140126993A1/en not_active Abandoned

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