An aero-engine blade tip shape and gap precision measurement method and device

Abstract

A kind of aero-engine blade tip blade tip topography and gap precision measurement method, for obtaining, by, obtain instantaneous gap value;Wherein, the flight time of laser round trip probe end face to the target to be measured, the speed of light;The method has the advantages of overcoming dynamic blur effect, high precision.And a kind of aero-engine blade tip blade tip topography and gap precision measurement device, the device is used to measure the gap of the target to be measured, the gap of the engine blade in the engine casing, corresponding measurement is carried out.The present application will greatly improve the measurement accuracy and spatial resolution of gap measurement, so as to master the high-precision data of blade tip topography and gap of complex blade tip configuration under real working condition.

Description

Technical Field

[0001] This invention relates to the field of precision measurement technology, and in particular to a method and apparatus for precision measurement of the morphology and clearance of aero-engine blade tips. Background Technology

[0002] As a core component of aero-engines, the performance of high-pressure turbines directly affects engine fuel consumption. To reduce the sensitivity of turbine performance to blade tip clearance during flight mission cycles, decrease leakage flow, and improve turbine efficiency, foreign designs for high-pressure turbine blade tips typically employ low-loss structures such as ribs, septa, and winglets to reduce the flow area at the blade tip clearance, thereby reducing leakage flow and improving efficiency. Therefore, the actual tip morphology and dynamic clearance distribution of complex blade configurations during aero-engine operation are crucial data for verifying the effectiveness of blade design. Current aero-engine blade clearance dynamic testing technology mainly relies on capacitance or eddy current principles, with sensor frequency responses typically around 230 kHz. This only allows for the measurement of average tip clearance and cannot obtain the dynamic tip morphology.

[0003] The reasons are as follows: (1) Since the electronic sensor takes about 4 microseconds to measure once, for a high-speed rotating blade with a typical linear velocity of 500m / s, the blade tip has rotated about 2mm during a single measurement. Therefore, the actual value of a single measurement is the average gap within a 2mm range of the blade tip, which means there is a dynamic fuzzy effect. (2) Since the typical blade tip width is only 10mm, when the blade rotates and sweeps across the electronic sensor, only 4-5 measurement values ​​can be captured, which cannot accurately describe the blade tip gap distribution.

[0004] In summary, existing electronic technologies are mainly suitable for measuring blade clearance in simple blade tip morphologies, such as compressor blades, but are incapable of accurately measuring the blade tip morphology and clearance in complex blade tip morphologies, such as high-pressure turbine blades. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for precise measurement of the morphology and clearance of aero-engine blade tips, which has the advantages of overcoming dynamic fuzziness effects and high precision.

[0006] To achieve the above objectives, this invention provides a method for precise measurement of the tip morphology and clearance of aero-engine blades, used to obtain... ,pass Obtain the instantaneous gap value ;in, The time it takes for the laser to travel to and from the probe end face to the target under test is denoted as . The speed of light; the method includes: step S1, emitting a laser beam toward the target to be tested, acquiring the signal light and the reference light, mixing them, and constructing a hybrid interference light field. Expression; Step S2, Obtain the mixed interference light field coherence function Expression; Step S3, for the mixed interference light field coherence function Perform Fourier transform to obtain the mixed interference optical field power spectral density function Expression; Step S4, based on power spectral density function Mixed interference light field After amplification, photoelectric conversion is performed to obtain the microwave power spectral density function in the frequency domain. Expression; Step S5, perform photoelectric conversion on the actual hybrid interference optical field to obtain the hybrid interference microwave field; and obtain the microwave power spectral density function of the hybrid interference microwave field in the time domain. Then it is transformed into the microwave power spectral density function in the frequency domain. ,get and .

[0007] Preferably, step S1 includes: based on The mixed interference light field at any time t Express:

[0008]

[0009] in, Let Q be the mixed interference optical field at any point at time t, where Q represents any point in physical terms only. Let be the reference light field at time t; for( The signal light field at a given moment.

[0010] Preferably, step S2 includes: using the coherence formula Obtaining the mixed interference light field coherence function expression:

[0011]

[0012] in, For the mutual coherence function of the mixed interference optical field; The average of the representative majors; The autocoherence function of the reference light field; Let be the autocoherence function of the signal light field; The mutual coherence function of the reference light; The mutual coherence function of the signal light; For conjugate operators; The phase change caused by arbitrary time delay.

[0013] Preferably, in step S3, the mixed interference light field power spectral density function for:

[0014]

[0015] in, The power spectral density function of the reference light field, Let be the power spectral density function of the signal light field. To perform the operation of taking the real part, The power spectral density components are those resulting from the cross-correlation between the reference light field and the signal light field.

[0016] Preferably, in step S4, photoelectric conversion is performed, and the microwave power spectral density function is... Represented as:

[0017]

[0018]

[0019]

[0020]

[0021] in, Let P be the detector response coefficient, Q be a constant term, and { } represents the convolution operation.

[0022] Preferably, step S5 includes step S51, performing photoelectric conversion on the actual hybrid interference optical field to obtain a hybrid interference microwave field; and acquiring its time-domain signal using an ADC to obtain the microwave power spectral density function in the time domain. Step S52, for the microwave power spectral density function in the time domain The data is chirped Z-transformed to the frequency domain, and then low-pass filtered to obtain the microwave power spectral density function in the frequency domain. Step S53, for the microwave power spectral density function in the frequency domain Perform an inverse Fourier transform and fit its peak value to obtain... Step S54, instantaneous gap value for: .

[0023] A precision measurement device for the blade tip morphology and clearance of an aero-engine is disclosed, used to implement the aforementioned precision measurement method for the blade tip morphology and clearance of an aero-engine. The device is used to measure the clearance of the target under test and the clearance of engine blades within the engine casing. The device includes: a femtosecond laser for emitting laser light; an optical circulator connected to the femtosecond laser to receive the laser light and transmit it to other components; a high-temperature resistant fiber optic probe, one end connected to the optical circulator via a transmission fiber and the other end connected to the target under test; receiving the laser light from the optical circulator and emitting it towards the target under test; the high-temperature resistant fiber optic probe acquiring the signal light emitted by the target under test and its own generated reference light, and mixing them to generate a mixed interference light field; the high-temperature resistant fiber optic probe transmitting the mixed interference light field to the optical circulator via the transmission fiber; and a computation module connected to the optical circulator, receiving the mixed interference light field from the optical circulator, and performing ADC acquisition and processing on its time-domain signal to obtain the instantaneous clearance value of the target under test.

[0024] Preferably, the optical circulator includes: a first port connected to a femtosecond laser to receive laser light from the femtosecond laser; a second port connected to the first port and connected to a high-temperature resistant fiber optic probe via a transmission fiber; and a third port connected to the first port, the second port, and the computing module, respectively.

[0025] Preferably, after the mixed interference light field is formed, the high-temperature resistant fiber optic probe transmits the mixed interference light field to the second port through the transmission fiber. The second port transmits the mixed interference light field to the third port. After receiving the mixed interference light field, the third port sends the mixed interference light field to the computing module.

[0026] Preferably, the computing module includes: an optical fiber amplifier connected to the third port, which receives and amplifies the mixed interference light field; a photodetector connected to the optical fiber amplifier, which receives the amplified mixed interference light field from the optical fiber amplifier, performs photoelectric conversion, and obtains the microwave power spectral density function of the mixed interference light field; a frequency demodulator connected to the photodetector, which receives and processes the microwave power spectral density function; and a computer connected to the frequency demodulator, which performs ADC acquisition on the time-domain signal and converts the power spectral density function in the time domain into the microwave power spectral density function in the frequency domain, thereby obtaining the instantaneous gap value.

[0027] In summary, compared with the prior art, the method and apparatus for precise measurement of blade tip morphology and clearance of aero-engines provided by the present invention have the following beneficial effects:

[0028] First, this invention uses a femtosecond laser as the detection laser, which shortens the sensing time of the leaf tip from the microsecond level to the sub-picosecond level, thus overcoming the dynamic ambiguity effect caused by the high-speed rotation of the leaf in principle.

[0029] Second, the present invention uses the optical-microwave real-time mapping method to demodulate the interference signal, improving the measurement frequency response from the hundreds of kHz level to the hundreds of MHz level, and realizing precise spatial resolution measurement of the blade tip height.

[0030] Third, this invention will significantly improve the measurement accuracy and spatial resolution of gap measurement, thereby enabling the mastery of high-precision data on the tip morphology and gap of blades with complex tip configurations under real working conditions. Attached Figure Description

[0031] Figure 1 This invention provides a precision measuring device for the morphology and clearance of aero-engine blade tips.

[0032] Figure 2 This refers to step S5 of the precision measurement method for the blade tip morphology and clearance of an aero-engine proposed in this invention.

[0033] Figure 3(a) shows the actual morphology of the high-pressure turbine blade tip in an embodiment of the present invention.

[0034] Figure 3(b) shows the tip clearance test results of an embodiment of the present invention.

[0035] Figure 4(a) shows a conventional capacitor device according to an embodiment of the present invention.

[0036] Figure 4(b) shows the existing capacitance test results of an embodiment of the present invention.

[0037] Figure 5 This is a flowchart illustrating a method for precise measurement of the blade tip morphology and clearance of an aero-engine, as proposed in this invention.

[0038] Figure label:

[0039] 1-Femtosecond laser, 2-Optical circulator, 3-Transmission fiber, 4-High temperature resistant fiber optic probe, 5-Fiber optic amplifier, 6-Photodetector, 7-Frequency demodulator, 8-Computer, 9-Engine casing, 10-Engine blade, 21-First port, 22-Second port, 23-Third port. Detailed Implementation

[0040] The following will be combined with the appendix in the embodiments of the present invention. Figure 1 ~Appendix Figure 5 The technical solutions, structural features, objectives and effects achieved in the embodiments of the present invention will be described in detail.

[0041] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0042] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0043] This invention provides a method and apparatus for precise measurement of the blade tip morphology and clearance of aero-engines, which can be applied to the precise measurement of the dynamic morphology and clearance of blade tips of complex blade configurations such as high-pressure turbine rotors during aero-engine testing.

[0044] like Figure 5 As shown, this invention proposes a method for precise measurement of the tip morphology and clearance of aero-engine blades, used to obtain... ,pass Obtain the instantaneous gap value ;in, This refers to the round-trip flight time of the laser from the probe end face to the target under test (the blade tip in this embodiment). The speed is the speed of light; the method includes:

[0045] Step S1: Emit a laser beam toward the target to be tested, acquire the signal beam and the reference beam, and mix them to construct a hybrid interference light field. Express;

[0046] Step S2, Obtain the mixed interference light field coherence function Express;

[0047] Step S3, for the mixed interference light field coherence function Perform Fourier transform to obtain the mixed interference optical field power spectral density function Express;

[0048] Step S4, based on the power spectral density function Mixed interference light field After amplification, photoelectric conversion is performed to obtain the microwave power spectral density function in the frequency domain. Express;

[0049] Step S5: Perform photoelectric conversion on the actual hybrid interference optical field to obtain a hybrid interference microwave field; and obtain the microwave power spectral density function of the hybrid interference microwave field in the time domain. Then it is transformed into the microwave power spectral density function in the frequency domain. ,get and .

[0050] Steps S1, S2, and S3 constitute the function construction process, i.e., generating a power spectral density function. The corresponding function model.

[0051] Steps S4 and S5 are based on the power spectral density function of the hybrid interference optical field. The microwave power spectral density function in the time domain of the mixed interferometric microwave field Equivalent; therefore, equivalent information can be obtained by performing time-domain acquisition and Fourier transform on the hybrid interferometric microwave field. This can be achieved through the microwave power spectral density function. The complete microwave power spectral density function is obtained by reverse calculation of the time-domain signal. Thus, the instantaneous gap value is obtained. .

[0052] Specifically, step S1 includes: based on The mixed interference light field at any time t Expressed as:

[0053]

[0054] in, Let Q be the mixed interference optical field at any point at time t, where Q represents any point in physical terms only. Let be the reference light field at time t; for( The signal light field at a given moment.

[0055] Specifically, step S2 includes:

[0056] Through the coherence formula Obtaining the mixed interference light field coherence function Expressed as:

[0057]

[0058] in, For the mutual coherence function of the mixed interference optical field; The average of the representative majors; The autocoherence function of the reference light field; Let be the autocoherence function of the signal light field; The mutual coherence function of the reference light; The mutual coherence function of the signal light; For conjugate operators; The phase change caused by arbitrary time delay.

[0059] in, The relationship with t is that, because the autocoherence function describes the coherence between the signal at the current moment and the signal after it has propagated a certain path (with phase increase), an arbitrary time delay needs to be added when performing ensemble averaging. To describe universal results.

[0060] Specifically, in step S3, the mixed interference light field power spectral density function Expressed as:

[0061]

[0062] in, The power spectral density function of the reference light field, Let be the power spectral density function of the signal light field. To perform the operation of taking the real part, The power spectral density components are those resulting from the cross-correlation between the reference light field and the signal light field.

[0063] As can be seen, although the time domain is only a few hundred femtoseconds, making it impossible to obtain time-domain interference fringes, it exhibits a clear interference phenomenon in the frequency domain, i.e., the power density increases with frequency. By flight time It oscillates periodically.

[0064] Specifically, in step S4, photoelectric conversion is performed, and the microwave power spectral density function in the frequency domain is... Represented as:

[0065]

[0066]

[0067]

[0068]

[0069] in, Let be the output microwave power spectral density function. Let P be the detector response coefficient, Q be a constant term, and { } represents the convolution operation.

[0070] Specifically, in steps S1 to S4, the interference signal that cannot be directly measured by a spectrometer is converted to the microwave band through real-time optical-microwave mapping, and has the same interference period.

[0071] Furthermore, given the current maturity of broadband instantaneous acquisition and recording equipment in the microwave band, in some scenarios, photoelectric conversion can be performed on actual hybrid interference optical fields to obtain hybrid interference microwave fields; due to the power spectral density function of the hybrid interference optical field... The microwave power spectral density function in the time domain of the mixed interferometric microwave field Equivalent; therefore, equivalent information can be obtained by performing time-domain acquisition and Fourier transform on the hybrid interferometric microwave field. Thus, the microwave power spectral density function in the time domain can be obtained. Then it is transformed into the microwave power spectral density function in the frequency domain. To achieve data acquisition, processing, and analysis, the theoretical and specific process of step S5 is as follows: Figure 2 As shown.

[0072] Specifically, step S5 includes,

[0073] Step S51: The actual hybrid interference optical field is photoelectrically converted to obtain a hybrid interference microwave field. Its time-domain signal (microwave pulse signal) is then acquired using an ADC (Analog-to-Digital Converter) to obtain the microwave power spectral density function in the time domain. ;

[0074] Step S52, for the microwave power spectral density function in the time domain The data is chirped Z-transformed to the frequency domain, and then low-pass filtered to obtain the microwave power spectral density function in the frequency domain. ;

[0075] The principle behind step S52 is that the chirped Z-transform also contains low-frequency and high-frequency components, resulting in a poor signal-to-noise ratio. Therefore, a low-pass filter is performed to remove high-frequency glitches and obtain a clean interference signal.

[0076] Step S53, for the microwave power spectral density function in the frequency domain Perform an inverse Fourier transform and fit its peak value to obtain... ;

[0077] The principle of step S53 is that the microwave power spectral density function in the frequency domain in step S52 is now... The microwave power spectral density function in the frequency domain in step S4 is satisfied. The representation can be obtained through inverse Fourier transform. Then, the distance is calculated.

[0078] Step S54, Instantaneous gap value for: ;in, It is the speed of light.

[0079] like Figure 1 As shown, the device is used to measure the gap of the target under test, specifically the gap of the engine blades 10 within the engine casing 9. The device includes:

[0080] Femtosecond laser 1, used to emit laser light;

[0081] Optical circulator 2 is connected to femtosecond laser 1, receives laser light from femtosecond laser 1, and transmits it to other components;

[0082] The high-temperature resistant fiber optic probe 4 is connected to the optical circulator 2 at one end via the transmission fiber 3 and to the target under test at the other end; it receives laser light from the optical circulator 2 and emits it towards the target under test; the high-temperature resistant fiber optic probe 4 acquires the signal light emitted by the target under test and the reference light it generates, and mixes them to produce a mixed interference light field;

[0083] The high-temperature resistant fiber optic probe 4 transmits the mixed interference optical field to the optical circulator 2 through the transmission fiber 3;

[0084] The principle is as follows: a portion of the laser light is transmitted and reflected back to the high-temperature resistant fiber optic probe 4 by the engine blade 10 as signal light, and the other portion of the laser light is reflected by the Fresnel effect at the end face of the high-temperature resistant fiber optic probe 4 as reference light.

[0085] The computing module is connected to the optical circulator 2, receives the mixed interference light field from the optical circulator 2, receives the external power spectral density function, and processes it to obtain the gap of the target under test.

[0086] In a preferred embodiment, the optical circulator 2 includes:

[0087] The first port 21 is connected to the femtosecond laser 1 and receives laser light from the femtosecond laser 1;

[0088] The second port 22 is connected to the first port 21 and is also connected to the high-temperature resistant fiber optic probe 4 via the transmission fiber optic 3.

[0089] And the third port 23 is connected to the first port 21, the second port 22 and the computing module respectively.

[0090] That is, during the laser emission process, the femtosecond laser 1 emits laser light to the first port 21, the first port 21 transmits the laser light to the second port 22, and the second port 22 transmits the laser light to the high-temperature resistant fiber optic probe 4 through the transmission fiber 3.

[0091] After the mixed interference light field is formed, the high-temperature resistant fiber optic probe 4 transmits the mixed interference light field to the second port 22 through the transmission fiber 3. The second port 22 transmits the mixed interference light field to the third port 23. After receiving the mixed interference light field, the third port 23 sends the mixed interference light field to the computing module.

[0092] In a specific embodiment, the computing module includes:

[0093] Fiber amplifier 5 is connected to the third port 23 to receive the mixed interference optical field and amplify it. Although the mixed interference optical field is only a hundred femtoseconds in the time domain, it exhibits obvious interference phenomena in the frequency domain, so amplification is required here.

[0094] The photodetector 6 is connected to the fiber amplifier 5, receives the amplified mixed interference light field from the fiber amplifier 5, performs photoelectric conversion, and obtains the microwave power spectral density function of the mixed interference light field;

[0095] Frequency demodulator 7 is connected to photodetector 6, receives microwave power spectral density function, and processes it;

[0096] Computer 8 is connected to frequency demodulator 7, receives external power spectral density function, and converts the power spectral density function into microwave power spectral density function in the time domain, thereby obtaining instantaneous gap value; in addition, this is equivalent to performing the content in step S5, and the parts not explicitly stated are prior art, which will not be described in detail here.

[0097] In a specific embodiment, a precision measurement device for the complex blade tip morphology and clearance of aero-engines is provided. Figure 1 The structure shown is used as an example to illustrate the best implementation scheme.

[0098] The femtosecond laser used in this embodiment has a repetition rate of 100 MHz, an output power of 22.30 mW, and a center wavelength of 1550 nm. The photodetector used has a bandwidth of 20 GHz, and the ADC sampling rate in the frequency demodulator is 40 GS / s. Experiments were conducted on a simulated high-speed rotating high-pressure turbine blade, and measurements were simultaneously performed using conventional capacitance technology. The existing capacitance (i.e., conventional capacitance) test results are shown in Figures 4(a) and 4(b), the actual blade used for measurement is shown in Figure 3(a), and the blade tip clearance measurement results under this invention are shown in Figure 3(b).

[0099] As can be seen, this invention can clearly obtain the tip morphology (two clear platform end faces at the top of the blade) and clearance value of the high-pressure turbine blade under rotating conditions. However, for traditional capacitance technology, due to insufficient measurement frequency response, the tip morphology is severely distorted (only two tips can be measured).

[0100] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. An aero-engine tip-shape and clearance precision measurement method, characterized in that, A method for obtaining , by , obtaining a time gap value ; wherein, is the time of flight of laser from the end face of the probe head to the target to be measured, is the speed of light; the method comprising: Step S1, emitting laser to the target to be measured, acquiring signal light and reference light and mixing to construct mixed interference light field expressing; Step S2, acquiring the mixed interference light field of the coherence function expressions; Step S3, Fourier transforming the coherence function of the mixed interference light field to obtain the power spectral density function of the mixed interference light field expressed as​​ Step S4, based on the power spectral density function The mixed interference optical field After amplification, photoelectric conversion is performed to obtain the microwave power spectral density function in the frequency domain Expression; Step S5, photoelectric conversion is performed on the actual mixed interference light field to obtain a mixed interference microwave field; and a time-domain microwave power spectral density function of the mixed interference microwave field is obtained , which is converted into a frequency-domain microwave power spectral density function , to obtain and ; The step S1 comprises: , the mixed interference light field at any time t is expressed as: wherein, is the mixed interference light field at an arbitrary point at time t, Q represents a physically arbitrary point only as an indicative meaning; is the reference light field at time t; is the signal light field at time t; is the signal light field at time t; Step S2 includes: using the coherence formula Obtaining the mixed interference light field coherence function Expressed as: wherein is the cross-coherence function of the mixed interference light field; represents the ensemble average; is the self-coherence function of the reference light optical field; is the self-coherence function of the signal light optical field; is the cross-coherence function of the reference light; is the cross-coherence function of the signal light; is the conjugate operator; is the phase change due to an arbitrary time delay; In said step S3, the mixed interference optical field whose power spectral density function is expressed as: wherein is the power spectral density function of the reference light optical field; is the power spectral density function of the signal light optical field; is the real part operation; is the power spectral density component of the mixed interference optical field under the cross-correlation of the reference light optical field and the signal light optical field; is the frequency of the mixed interference optical field.

2. The method of claim 1, wherein the method further comprises: determining the tip clearance of the blade of the turbine engine. In the step S4, photoelectric conversion is performed, and a microwave power spectral density function in the frequency domain is represented as: wherein is a constant term, Q is a constant term, and is a convolution operation.

3. The method of claim 2, wherein the method further comprises: The step S5 comprises, Step S51, photoelectric conversion is performed on the actual mixed interference optical field to obtain a mixed interference microwave field; the time domain signal thereof is collected by ADC to obtain a microwave power spectral density function in time domain ; Step S52, the microwave power spectrum density function in time domain The microwave power spectrum density function in frequency domain is obtained by performing the chirp Z transform to the frequency domain data and low-pass filtering ; Step S53, for the microwave power spectral density function in the frequency domain Perform an inverse Fourier transform and fit its peak value to obtain... ; Step S54, the time slot value is: .

4. An aero-engine tip-shape and clearance precision measuring device, characterized in that, The device is used for measuring the clearance of the engine blade (10) in the engine casing (9), and comprises: a femtosecond laser (1) for emitting laser; an optical circulator (2) connected with the femtosecond laser (1) and receiving laser from the femtosecond laser (1) and transmitting to other components; a high-temperature-resistant optical fiber probe (4) connected with the optical circulator (2) through a transmission optical fiber (3) at one end and connected with a target to be measured at the other end, receiving laser from the optical circulator (2) and emitting to the target to be measured, and obtaining signal light emitted by the target to be measured and reference light generated by itself, and mixing to generate mixed interference light field; the high-temperature-resistant optical fiber probe (4) transmits the mixed interference light field to the optical circulator (2) through the transmission optical fiber (3); an operation module connected with the optical circulator (2), receiving the mixed interference light field from the optical circulator (2), and performing ADC collection and processing on the time-domain signal to obtain the instantaneous clearance value of the target to be measured.

5. The device for measuring the tip shape and clearance of an aero-engine blade according to claim 4, characterized in that, The optical circulator (2) comprises: a first port (21) connected with the femtosecond laser (1) and receiving laser from the femtosecond laser (1); a second port (22) connected with the first port (21) and connected with the high-temperature-resistant optical fiber probe (4) through the transmission optical fiber (3); and a third port (23) connected with the first port (21), the second port (22) and the operation module.

6. The device for measuring the tip shape and clearance of an aero-engine blade according to claim 5, wherein, After the mixed interference light field is formed, the high-temperature-resistant optical fiber probe (4) transmits the mixed interference light field to the second port (22) through the transmission optical fiber (3), the second port (22) transmits the mixed interference light field to the third port (23), and the third port (23) transmits the mixed interference light field to the operation module after receiving the mixed interference light field.

7. The device according to claim 6, wherein, The operation module comprises: an optical fiber amplifier (5) connected with the third port (23) and receiving the mixed interference light field for amplification processing; a photoelectric detector (6) connected with the optical fiber amplifier (5) and receiving the amplified mixed interference light field from the optical fiber amplifier (5) for photoelectric conversion to obtain the frequency-domain microwave power spectral density function of the mixed interference light field; a frequency demodulator (7) connected with the photoelectric detector (6) and receiving the frequency-domain microwave power spectral density function for processing; a computer (8) connected with the frequency demodulator (7) and performing ADC collection on the time-domain signal and converting the time-domain power spectral density function into the frequency-domain microwave power spectral density function to obtain the instantaneous clearance value.

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