Method for measuring the deformation of blades of a rotor of a turbine engine and associated turbine engine
The method using radially internal and external sensors to measure blade transit times in turbomachines enhances deformation detection accuracy and compatibility with high-temperature environments by eliminating static deformations and optimizing sensor placement.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2025-10-28
- Publication Date
- 2026-06-25
Smart Images
Figure FR2025051002_25062026_PF_FP_ABST
Abstract
Description
[0001] DESCRIPTION
[0002] Title of the invention: Method for measuring the deformation of rotor blades of a turbomachine and associated turbomachine
[0003] technical field
[0004] The invention relates to the technical field of turbomachinery for aircraft.
[0005] In particular, the invention relates to a method for measuring the deformation of blades of a rotor of a turbomachine and a turbomachine comprising a computer configured to implement such a method.
[0006] Previous techniques
[0007] During the design, verification, and validation of a turbomachine, it is necessary to experimentally characterize the vibrational behavior of the rotating elements of the turbomachine.
[0008] To achieve this, dedicated tests are implemented, for example to experimentally characterize blade deformations.
[0009] We know from the state of the art a method for measuring blade deformations consisting of using strain gauges, for example sensors glued onto the blades, which are able to measure deformations by knowing a constitutive law of the material of the blades.
[0010] However, the integration of these strain gauges can disrupt the dynamic behavior of the turbomachine being characterized, as well as the aerodynamics of the airflow within the turbomachine. Furthermore, these strain gauges are not suitable for the temperatures present in certain stages of the turbomachine, particularly the temperatures found in the low-pressure turbine.
[0011] We also know of the state of the art for non-intrusive measurements consisting of measuring the blade transit time at their tip, that is, at their radially outer end, the radial direction being orthogonal to the axis of rotation of the rotating elements of the turbomachine. Such measurements are known to those skilled in the art under the English term "Tip-Timing".
[0012] The blade tip passage time measurements are not suitable for the blades of a low-pressure turbomachine turbine, each of which has a heel at its radially external end.
[0013] To circumvent this difficulty, edge-timing measurements can be taken at the leading or trailing edge of the blade. Such measurements are known to those skilled in the art as "edge-timing".
[0014] The "Tip-Timing" and "Edge-Timing" methods known from the state of the art are generally characterized by deformation detectability thresholds on the order of 100 pm.
[0015] Another known method, consisting of measuring variations in blade length along a radial axis to deduce blade vibration modes, is described in FR-B-3 037 394.
[0016] Description of the invention
[0017] The present invention aims to overcome all or part of the aforementioned problems and to provide a method for measuring the deformation of blades of a turbine rotor having a blade deformation detection threshold lower than known methods of the prior art.
[0018] The invention relates to a method for measuring the deformation of the blades of a turbomachine rotor, the turbomachine comprising at least one radially internal sensor configured to measure blade transit times from a radially internal measuring point, and a plurality of radially external sensors configured to measure blade transit times from radially external measuring points with different azimuths, the distance between each radially external measuring point and an axis of rotation of the turbomachine being strictly greater than the distance between said radially internal measuring point and the axis of rotation of the turbomachine, the method comprising: - calculating, for each radially external sensor, for each blade, and for each revolution of the rotor, the difference between, on the one hand,the passage time of the blade in question, measured by the radially external sensor in question at the considered lathe, and, on the other hand, the passage time of one of the blades, measured by said radially internal sensor or by one of the radially internal sensors, which is the passage time closest to said passage time of the blade in question, measured by the radially external sensor in question at the considered lathe; and,
[0019] - the use, in a modeling for each radially external sensor considered, for each blade considered, and for each turn considered, of the corresponding calculated differences to deduce dynamic deflections of the blades.
[0020] The static deflection of a turbomachine blade is the measure of the displacement or deformation of the blade under the effect of static forces that do not vary over time.
[0021] Dynamic blade deflection is the measurement of the blade's displacement or deformation under the influence of time-varying dynamic forces, such as turbomachine vibrations or air pressure variations. Dynamic deflection takes into account the effects of temporal variations, such as turbomachine operating disturbances or resonance phenomena.
[0022] Using the corresponding calculated differences, we eliminate a time related to the static deformations of the blades and measure a time related to the dynamic deformations of the blades.
[0023] Unlike prior art methods for measuring tip or edge timing that estimate blade timing based on rotor rotation time and blade number, the method according to the invention uses blade timing measured by the internal radial sensor(s). This reduces the detection threshold for blade deformations and thus improves measurement accuracy compared to prior art methods for measuring tip or edge timing. The method for measuring blade deformation of a turbomachine rotor according to the invention is compatible with both tip timing and edge timing measurements.
[0024] According to an initial design, each radially external sensor of the turbomachine is configured to perform blade tip passage time measurements. This method of measuring blade deformations is known to those skilled in the art as "Tip-Timing".
[0025] According to a second alternative design, each radially external sensor of the turbomachine is configured to perform blade passage time measurements at the blade trailing edge or blade leading edge. This method of measuring blade deformation is known to those skilled in the art as "Edge-Timing".
[0026] Advantageously, the turbomachine comprising a plurality of radially internal sensors configured to perform blade transit time measurements from radially internal measuring points with different azimuths, the method comprises:
[0027] - the calculation, for each radially external sensor, for each blade, and for each revolution made by the rotor, of the difference between, on the one hand, the passage time of the blade in question measured by the radially external sensor in question at the revolution in question and, on the other hand, the passage time of one of the blades which is measured by one of the radially internal sensors and which is the passage time closest to said passage time of the blade in question measured by the radially external sensor in question at the revolution in question; and
[0028] - the use, in said modeling for each radially external sensor considered, for each blade considered, and for each tower considered, of the corresponding calculated differences to deduce dynamic deflections of the blades.
[0029] By using the passage time closest to said passage time of the blade in question measured by the radially external sensor in question on the lathe in question, the accuracy of measuring blade deformations is further improved.
[0030] Advantageously, the turbomachine includes the same number of radially internal and radially external sensors.
[0031] Advantageously, the radially inner and outer sensors are arranged in pairs, the radially inner and outer sensors of each pair having the same azimuth.
[0032] Advantageously, said or each radially internal sensor is located at a radial distance from the axis of rotation of the turbomachine which is between 0% and 50% of a distance range which goes from a radial distance taken between the axis of rotation of the turbomachine and the foot of one of the blades whose passage time is measured, to a radial distance taken between the axis of rotation of the turbomachine and the top of one of the blades whose passage time is measured, in particular between 10% and 30% of said distance range.
[0033] Advantageously, each radially external sensor is located at a radial distance from the axis of rotation of the turbomachine which is between 50% and 100% of said distance range, in particular between 60% and 90% of said distance range.
[0034] Optionally, the method for measuring the deformation of blades of a turbine rotor includes prior numerical simulations, including finite element simulations, to determine an inside radial distance corresponding to a blade vibration node, said or each radially inside sensor being located at said inside radial distance.
[0035] The vibration node of a blade corresponds to the radial position at which the blade in question does not vibrate, or to the radial position at which the blade in question is subject to a minimum of vibration.
[0036] Optionally, the method for measuring the deformation of turbine blades on a turbomachine rotor includes preliminary numerical simulations, particularly finite element simulations, to determine an outer radial distance corresponding to a blade vibration antinode, with each radially outer sensor located at said outer radial distance. The vibration antinode of a blade corresponds to the radial position at which the blade in question is subject to maximum vibration.
[0037] Optionally, the method for measuring the deformation of the blades of a turbomachine rotor includes the calculation of an instantaneous turbomachine regime as a function of the blade passage times measured by said internal radial sensor(s) and associated angular positions of the rotor, said modeling including the use of the calculated instantaneous turbomachine regime to deduce the dynamic blade deflections.
[0038] The accuracy of calculating the turbomachine regime, and therefore the dynamic deflections of the blades, is thus improved compared to calculations carried out from measurements of time of passage at the tip or edge of the blade known from the prior art.
[0039] Preferably, the transit times measured by the radially internal and external sensors are measured cumulatively.
[0040] Optionally, the calculation of the instantaneous turbomachine speed includes:
[0041] - the formation of pairs of values, for said or each radially internal sensor, for each blade, and for each revolution made by the rotor, between, on the one hand, the passage time of the blade in question measured by the radially internal sensor in question at the revolution in question and, on the other hand, the associated angular position of the rotor which is measured cumulatively; and
[0042] - the ranking of all pairs of values in ascending order of the passage times measured by said or the radially internal sensors.
[0043] Such a classification allows for simplified manipulation of pairs of values. The cumulatively measured angular position of the rotor is not a modulo 2π measurement and can take values strictly greater than 360 degrees.
[0044] Optionally, the calculation of the instantaneous speed of the turbomachine Reg(t) is performed piecewise Reg p (t), said calculation comprising, for any time t between two values of transit time ToaRp, ToaRp+i measured by said or the radially internal sensors which are successive in ascending order, the intermediate calculations of:
[0045] - Reg p F = ( —<ï)p+1 <ï)p— ) x - with the values of the
[0046]
[0047] ToaR p+1 -ToaRp J 6 p p
[0048] angular position of the rotor, measured in degrees, associated with measured ToaR transit times p , ToaR p+1 measured in seconds; and
[0049] - Reg p oy = — — —2 9p ~ Nc with Ne the number of radially internal sensors;
[0050] M°y_ Q Moy p 1 our determine Reg v (t) = —
[0051]
[0052] apv > ToaR p+ -1— - -ToaR p ( v t — ToaR v} + Reg a ^ p oy Reg p F is expressed in revolutions per minute.
[0053] When the turbomachine includes several radially internal sensors, the accuracy of calculating the instantaneous speed is improved due to the higher number of measurement points used for this piecewise interpolation.
[0054] Advantageously, said modeling includes the use of a correction parameter for an azimuth offset between the radially outer sensor considered and the radially inner sensor which measures the passage time closest to the passage time of the blade considered at the considered turn.
[0055] Thus, the accuracy of said modeling is further improved. Advantageously, said modeling includes the calculation of dynamic blade deflections such as:
[0056] dvr RegToat i k ),. n D ij,k = 2n ■ Ray - 60 ' ' ■ (T oa iJ>k - Tref) - Radius • — (y + / ?)
[0057]
[0058] in which i is the dawn considered;
[0059] j is the turn under consideration;
[0060] k is the radially external sensor under consideration;
[0061] Radius is the distance between the axis of rotation of the turbomachine and the radially outer measurement point of the radially outer sensor considered;
[0062] Reg(t) the instantaneous operating regime of the turbomachine;
[0063] Toai,j,k is the passage time of the blade in question, measured by the radially external sensor in question at the considered lathe; Tref is the passage time of one of the blades, measured by the said radially internal sensor or by one of the radially internal sensors, and which is the passage time closest to the passage time of the blade in question, measured by the radially external sensor in question at the considered lathe. Therefore, Tref = ToaR t r z with l the index of said radially internal sensor, which measures the passage time Tref of the blade i' at the turn j'.
[0064] y is the oriented angle between the radially external sensor considered and the radially internal sensor which measures the passage time closest to the passage time of the blade considered at the considered turn;
[0065] P is a correction parameter for an azimuth offset between the radially outer sensor considered and the radially inner sensor that measures the passage time closest to the passage time of the blade considered at the considered revolution. P also corrects a dependence on the indices "i, i', j and j'" of the Toatj terms k and Tref for each calculation of a dynamic deflection of the blades D^.
[0066] For example, a gain of more than two orders of magnitude in the detectability threshold of blade deformations of the order of 40 pm has been observed, and a further two and six orders of magnitude improvement in the accuracy of blade deformation measurements.
[0067] In a particular embodiment, the method for measuring the deformation of the blades of a turbine rotor is implemented by computer.
[0068] The present invention also relates to a computer program comprising code instructions which, when the program is executed by a computer, lead the computer to implement the process defined above.
[0069] The present invention also relates to a computer-readable data carrier on which a computer program as defined above is recorded.
[0070] The present invention also relates to a turbomachine comprising at least one radially internal sensor configured to perform blade passage time measurements from a radially internal measurement point, and a plurality of radially external sensors configured to perform blade passage time measurements from radially external measurement points having different azimuths, the distance between each radially external measurement point and an axis of rotation of the turbomachine being strictly greater than the distance between said radially internal measurement point and the axis of rotation of the turbomachine, the turbomachine further comprising a computer configured to implement the method of measuring the deformation of blades of a rotor of a turbomachine as defined above.
[0071] Brief description of the drawings
[0072] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:
[0073] [Fig 1] schematically illustrates a turbomachine equipped with a computer according to an example of an embodiment of the invention;
[0074] [Fig 2] schematically illustrates radially external and internal sensors of the turbomachine in Figure 1;
[0075] [Fig 3] schematically illustrates a dynamic deflection of a turbine blade of the turbomachine in Figure 1;
[0076] [Fig 4] illustrates in perspective a blade of a low-pressure turbine of the turbomachine in Figure 1; and
[0077] [Fig 5] schematically illustrates a method for measuring the deformation of the blades of a turbine rotor according to an example of an embodiment of the invention.
[0078] Detailed description
[0079] Figure 1 represents a turbomachine 2 with longitudinal axis X coinciding with an axis of rotation of the rotating elements of the turbomachine 2. The turbomachine 2 comprises, from upstream to downstream with reference to the direction of gas flow through the turbomachine 2, a blower 4, a low pressure compressor 6, a high pressure compressor 8, a combustion chamber 10, a high pressure turbine 12, and a low pressure turbine 14.
[0080] The turbomachine 2 further includes a computer 16 capable of implementing a method for measuring the deformation of the blades 18 of the turbomachine 2.
[0081] Figure 2 represents a rotating blade stage 18 of the turbomachine 2. The turbomachine 2 includes a plurality of radially internal sensors 20 and a plurality of radially external sensors 22. More specifically, the radially internal and external sensors 20, 22 are arranged on a stator stage of the turbomachine 2 and measure the passage times of the blades 18 of a rotor stage of the turbomachine 2.
[0082] Each radially internal sensor 20 is capable of measuring the blade passage times 18 from a radially internal measuring point. The radially internal sensors 20 are arranged at different azimuths. All the radially internal sensors 20 are at the same radial distance from the axis of rotation of the turbomachine 2.
[0083] Each radially external sensor 22 is capable of measuring the passage times of the blades 18 from a radially external measuring point. The radially external sensors 22 are arranged at different azimuths. All the radially external sensors 22 are at the same radial distance from the axis of rotation of the turbomachine 2.
[0084] The radially external sensors 22 are strictly further from the axis of rotation of the turbomachine 2 than the radially internal sensors 20.
[0085] Each radially inner sensor 20 here has the same azimuth as one of the radially outer sensors 22. Alternatively, the radially inner sensors 20 and the radially outer sensors 22 could have different azimuths.
[0086] In the example shown, the turbomachine 2 comprises fewer radially internal sensors 20 than radially external sensors 22. Alternatively, the turbomachine 2 could comprise the same number of radially internal and external sensors 20, 22, or a greater number of radially internal sensors 20. As a variant, the turbomachine 2 could have only one radially internal sensor 20.
[0087] With reference to Figure 3, the moving blades 18 undergo deflections relative to their rest position 24. In particular, each moving blade 18 undergoes a tangential displacement of its radially outer end in reaction to vibrations of the turbomachine 2. These deflections can be decomposed into a so-called static component which is generated by forces not varying over time, and a so-called dynamic component which is generated by forces which vary over time.
[0088] Figure 3 further shows a radially internal measurement point 26 located near a blade vibration node 18, a radially external measurement point for a blade edge measurement 28 located at a blade vibration antinode 18, and a radially external measurement point for a blade tip measurement 30. The radially external measurement point for a blade edge measurement 28 corresponds, for example, to a measurement known to those skilled in the art as "Edge-Timing." The radially external measurement point for a blade tip measurement corresponds, for example, to a measurement known to those skilled in the art as "Edge-Timing."
[0089] Preliminary numerical simulations, particularly using finite elements, can be performed to determine an inner radial distance corresponding to a blade vibration node 18 so as to position each radially inner sensor 20 at the inner radial distance from the axis of rotation. Similarly, preliminary numerical simulations, particularly using finite elements, can be performed to determine an outer radial distance corresponding to a blade vibration antinode 18 so as to position each radially outer sensor 22 at the outer radial distance from the axis of rotation.
[0090] Figure 4 shows in perspective the blade 18 and radially external measurement points at the leading and trailing edges 28a, 28b.
[0091] Figure 5 schematically represents the method for measuring the deformation of the blades 18 of the turbomachine 2. We start with a step 32 during which measurements are taken, with the radially external sensors 22, of the passage times Toa of the blades 18 from radially external measurement points 28 or 30, and measurements are taken, with the radially internal sensors 20, of the passage times ToaR of the blades 18 from radially internal measurement points 26.
[0092] Turbomachine 2 includes an analog-to-digital converter (not shown) to convert the Toa and ToaR transit time measurements taken by the radially internal and external sensors 20, 22.
[0093] Then, in step 34, the converted Toa and ToaR transit times and angular positions are loaded. kradially external sensors 22, angular positions pi of radially internal sensors 20, number of blades Na, number of radially internal sensors Ne, angular deviations a L between each blade 18 and a reference blade, hereafter called aubei, along the circumferential direction of the turbomachine 2, there is an angular deviation between the rotor reference frame and the stator reference frame coo, and an angular deviation between the reference blade aubei and the stator ao. The angles are measured with respect to a reference direction R which is vertical upwards.
[0094] Then, in step 36, a calculation of the dynamic deflections of the blades 18 is carried out.
[0095] To do this, we start with a sub-step 36a of calculating the angular positions of the rotor associated with the ToaR transit times measured by the radially internal sensors 20.
[0096] The calculation of the rotor's angular positions is, for example, carried out in the following way:
[0097] (jùij iÇrotor / stator) = a)(rotor / blade l) stator + ooDawn 1 / dawn i) stator
[0098]
[0099] +(jù(blade i / stator)ij i In other words, the angle of the rotor relative to the stator which is associated with the measurement of the passage time ToaR for the blade i, at turn j and measured by the radially inner sensor 1 is equal to the sum of the angle between the reference frame of the rotor and the reference blade aubei, the angle between the blade i considered and the reference blade aubei, and the angle of the blade i considered relative to the reference frame of the stator when it passes in front of the radially inner sensor 1 considered at the turn j considered.
[0100] In particular, these terms are:
[0101] ù aube i / stator = (p t + 360 • (d — 1)
[0102] 360
[0103] a)(dawn 1 / dawn i) = - x (i — 1)
[0104] has
[0105] (joÇrot / dawn 1) = &>0— a0
[0106] Next, we carry out a substep 36b of indexing during which we form pairs of values for each radially internal sensor 1, for each blade i, and for each revolution j made by the rotor, between, on the one hand, the passage time ToaRi,j,i of the blade i considered measured by the radially internal sensor 1 considered at the revolution j considered and, on the other hand, the associated angular position of the rotor coi,j,i which is measured cumulatively, the angular position of the rotor being measured relative to the stator of the turbomachine 2. The passage times Toa, ToaR of the blades 18 are also measured cumulatively.
[0107] When the pairs of values (ToaRi,j,i; coi,j,i) are formed, the set of pairs of values is ranked in ascending order of the ToaRi,j,i transit times measured by the radially internal sensors 20.
[0108] The pairs of values (ToaRi,j,i; coi,j,i) ranked are subsequently indexed (ToaRp; co P ).
[0109] Then, a substep 36c is performed to calculate the instantaneous speed Reg(t) of the turbomachine 2 as a function of the passage times ToaRi,j,i of the blades 18 measured by the radially internal sensors 20 and the associated angular positions of the rotor, the calculation of the instantaneous speed Reg(t) including in particular the use of the pairs of classified and indexed values (ToaRp; co P ).
[0110] The calculation of the instantaneous speed of the turbomachine Reg(t) is, for example, performed by interpolation and by pieces Reg p(t). To do this, during a first intermediate calculation, an approximation of the instantaneous regime is calculated by subtracting two successive acquisitions Reg p F .
[0111] For any time t between two transit time values ToaRp, ToaRp+i measured by the radially internal sensors 20 which are successive in ascending order, we calculate:
[0112] Rp n DF = ( ^P+I ~ M P \ £
[0113]
[0114] \ToaR p+1 - ToaR p J 6
[0115] With (jp,a> p+1 The values of the rotor's angular position, measured in degrees, associated with the measured transit times ToaRp, ToaRp+i, measured in seconds. Reg p F is expressed in revolutions per minute.
[0116] In a second intermediate calculation, a Regp moving average is calculated. Oyapproximations calculated during the first intermediate calculation.
[0117] T,.., • lin Moy Regp
[0118] In particular, we calculate Reg p = - F +Regp- - — - — Nc
[0119] .
[0120] The regime Reg(t) is then determined by piecewise interpolation:
[0121] -, Average -, Average
[0122] n Re 9p+1 Re 9p f „ n A in Mo V
[0123] Re 9v^> = V ~ ToaRp) + Reg.
[0124]
[0125] r 1 OCLKp^.1 — 1 OCLKp r ~
[0126] We then perform a sub-step 36d of calculation, and optionally of correction, of the dynamic deflections.
[0127] In substep 36d, for each radially external sensor k, for each blade i, and for each revolution j of the rotor, the difference is calculated between, on the one hand, the passage time Toai,j,k of the blade i considered, measured by the radially external sensor k considered at the revolution j considered, and, on the other hand, the passage time Tref of one of the blades i', at a revolution j', which is measured by one of the radially internal sensors 1 and which is the passage time ToaR^ t the closest to said passage time Toai,j,k of the considered dawn i measured by the radially external sensor k considered at the considered turn j.
[0128] We then use in models for each radially external sensor k considered, for each blade i considered, and for each turn j considered, the corresponding calculated differences to deduce dynamic deflections of the blades 18. These models include in particular the use of the instantaneous regime Reg(t) of the turbomachine.
[0129] Optionally, in each model we use a correction parameter for the azimuth offset between the radially external sensor k considered and the radially internal sensor 1 which measures the passage time Tref, also called ToaRi' ',1, closest to the passage time Toai,j,k of the blade i considered at the turn j considered.
[0130] In particular, each model includes the calculation of the dynamic deflections of the 18 blades as follows:
[0131] = 2TT ■ Radius ■ Re9 (T °^ l i ^. (Toa iJik - Tref) - Radius ■ ygjj (r + / ?)
[0132]
[0133] With i the number of the blade 18 considered, j the revolution considered, k the radially external sensor 22 considered, Radion the distance between the axis of rotation of the turbomachine 2 and the radially external measurement point 28, 30 of the radially external sensor 22 considered, Reg(t) the instantaneous speed of the turbomachine, Toai,j,k the passage time of the blade i considered measured by the radially external sensor k considered at revolution j considered, Tref the passage time of one of the blades i' at revolution j which is measured by one of the radially internal sensors 1 and which is the passage time closest to said passage time Toai,j,k of the blade i considered measured by the radially external sensor k considered at revolution j considered, y the oriented angle, positive or negative, which is measured between the radially external sensor k considered and the radially internal sensor 1 which measures the passage time Tref closest to the passage time Toai,j,k of the blade i considered at the considered revolution j, P the correction parameter for an azimuth offset between the radially outer sensor k considered and the radially inner sensor 1 which measures the passage time Tref closest to the passage time Toai,j,k of the blade i considered at the considered revolution j. Advantageously, the instantaneous speed of the turbomachine Reg(t) is calculated piecewise Reg, p t).
[0134] The correction parameter P for an azimuth offset between the radially external sensor k considered and the radially internal sensor 1 which measures the passage time Tref closest to the passage time Toai,j,k of the blade i considered at the considered revolution j is, for example, equal to:
[0135] 360
[0136] P = [(1 - l') + Na ■ (j - j')] * — - + (0 k - 0i)
[0137]
[0138] IN a
[0139] With i' dawn 18 whose passage time Tref, at turn j', measured is closest to the passage time Toai,j,k of dawn i considered at turn j considered.
[0140] Advantageously, the method of measuring the deformation of the blades 18 of the turbomachine 2 continues with a step 38 of characterizing the types of response of the blades 18, in particular synchronous and asynchronous responses, and then with a step 40 of calculating the stresses during which the calculated dynamic deflections are converted into stresses.
Claims
DEMANDS 1. A method for measuring the deformation of blades (18) of a rotor of a turbomachine (2), the turbomachine (2) comprising at least one radially inward sensor (20) configured to perform blade (18) transit time measurements from a radially inward measuring point (26), and a plurality of radially outward sensors (22) configured to perform blade (18) transit time measurements from radially outward measuring points (28, 30) having different azimuths, the distance between each radially outward measuring point (28, 30) and an axis of rotation of the turbomachine (2) being strictly greater than the distance between said radially inward measuring point (26) and the axis of rotation of the turbomachine (2), the method comprising: - the calculation, for each radially external sensor (22), for each blade (18), and for each revolution completed by the rotor, of the difference between, on the one hand, the passage time of the blade (18) in question measured by the radially external sensor (22) in question at the revolution in question and, on the other hand, the passage time of one of the blades (18) which is measured by said radially internal sensor (20) or by one of the radially internal sensors (20) and which is the passage time closest to said passage time of the blade (18) in question measured by the radially external sensor (22) in question at the revolution in question; and - the use, in a modeling for each radially external sensor (22) considered, for each blade (18) considered, and for each turn considered, of the corresponding calculated differences to deduce dynamic deflections of the blades (18).
2. A method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to claim 1, the turbomachine (2) comprising a plurality of radially internal sensors (20) configured to perform blade (18) passage time measurements from radially internal measuring points (26) having different azimuths, wherein the method comprises: - the calculation, for each radially external sensor (22), for each blade (18), and for each revolution made by the rotor, of the difference between, on the one hand, the passage time of the blade (18) considered measured by the radially external sensor (22) considered at the revolution considered and, on the other hand, the passage time of one of the blades (18) which is measured by one of the radially internal sensors (20) and which is the passage time closest to said passage time of the blade (18) considered measured by the radially external sensor (22) considered at the revolution considered.
3. Method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to claim 1 or 2, comprising prior numerical simulations, in particular by finite elements, to determine an inner radial distance corresponding to a blade vibration node (18), said or each radially inner sensor (20) being located at said inner radial distance.
4. Method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to any one of claims 1 to 3, comprising prior numerical simulations, in particular by finite elements, to determine an outer radial distance corresponding to a blade vibration antinode (18), each radially outer sensor (22) being located at said outer radial distance.
5. Method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to any one of claims 1 to 4, comprising calculating an instantaneous regime of the turbomachine (2) as a function of the passage times of the blades (18) measured by said or the radially internal sensor(s) (20) and of angular positions of the rotor associated therewith, said modeling comprising using the calculated instantaneous regime of the turbomachine (2) to deduce the dynamic deflections of the blades (18).
6. Method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to claim 5, wherein the calculation of the instantaneous speed of the turbomachine (2) comprises: - the formation of pairs of values, for said or each radially internal sensor (20), for each blade (18), and for each revolution made by the rotor, between, on the one hand, the passage time of the blade (18) considered, measured by the radially internal sensor (20) considered, at the revolution considered, and, on the other hand, the associated angular position of the rotor which is measured cumulatively; and - the ranking of all pairs of values in ascending order of the passage times measured by said or the radially internal sensors (20).
7. A method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to claim 6, wherein the calculation of the instantaneous speed of the turbomachine Reg(t) is performed piecewise Reg p (t), said calculation including, for any time t between two values of passage time ToaRp, ToaR P+i measured by said radially internal sensor(s) (20) which are successive in ascending order, the intermediate calculations of: - Reg p F = ( —<ï)p+1 <ï)p— ) x - with the values of the ToaR p+1 -ToaR p J 6 p p angular position of the rotor, measured in degrees, associated with the measured transit times ToaRp, ToaR P +i, measured in seconds; and - Reg p oy = — — —2 9p ~ Nc with Ne the number of radially internal sensors (20); M°y_ Q Mean to determine Reg v (t) = — - — - (t — ToaR v ) + Regp Oy . 1 apv > ToaR p+1 -ToaR p v ap 8. Method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to any one of claims 1 to 7, wherein said modeling includes the use of a correction parameter for an azimuth offset between the radially outer sensor (22) considered and the radially inner sensor (20) which measures the passage time closest to the passage time of the blade (18) considered at the revolution considered.
9. Method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to any one of claims 1 to 8, wherein said modeling includes the calculation of the dynamic deflections of the blades (18) as: dvr Reg(Toai j k ).. n D i,j,k = 2n ■ Ray - 6() ' ' ■ (Toaij' k - Tref) - Radius • — (y + / ?) in which i is the dawn (18) considered; j is the turn under consideration; k is the radially external sensor (22) considered; Radius is the distance between the axis of rotation of the turbomachine (2) and the radially outer measurement point (28, 30) of the radially outer sensor (22) considered; Reg(t) the instantaneous regime of the turbomachine (2); Toai,k is the passage time of the considered blade (18) measured by the radially external sensor (22) considered at the considered turn; Tref is the time of passage of one of the blades (18) which is measured by said radially inner sensor (20) or by one of the radially inner sensors (20) and which is the passage time closest to said passage time of the blade (18) considered measured by the radially outer sensor (22) considered at the turn considered; y is the oriented angle between the radially external sensor (22) considered and the radially internal sensor (20) which measures the passage time closest to the passage time of the blade (18) considered at the considered turn; P is a correction parameter for an azimuth offset between the radially external sensor (22) considered and the radially internal sensor (20) which measures the passage time closest to the passage time of the blade (18) considered at the considered turn.
10. Turbomachine (2) comprising at least one radially inward sensor (20) configured to perform blade (18) passage time measurements from a radially inward measuring point (26), and a plurality of radially outward sensors (22) configured to perform blade (18) passage time measurements from radially outward measuring points (28, 30) having different azimuths, the distance between each radially outward measuring point (28, 30) and an axis of rotation of the turbomachine (2) being strictly greater than the distance between said radially inward measuring point (26) and the axis of rotation of the turbomachine (2), characterized in that the turbomachine (2) comprises a computer (16) configured to implement the method for measuring the deformation of blades (18) of a rotor of a turbomachine (2) according to any one of claims 1 to 9.