A split type optical fiber sensing system for dynamic strain of a high temperature turbine rotor system

Abstract

The application discloses a split type optical fiber sensing system for dynamic strain of a high-temperature turbine rotor system, which comprises a blackbody light source (2), an optical fiber Fabry-Perot sensor, an optical fiber collimator (5), a surface optical wedge (7), a surface array infrared detector (6) and a signal processing module (8). The surface optical wedge and the surface array detector are directly used as demodulation elements, transverse shaking of a rotating shaft only causes translation of a light spot position, does not affect relative light intensity distribution of the light spot, and reduces influence on demodulation.

Description

Technical Field

[0001] This invention relates to the field of fiber optic strain sensing, specifically a split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system. Background Technology

[0002] High-temperature turbine rotor systems play an irreplaceable role in aero-engines, but their operating environment is harsh: high temperature and pressure, fluid erosion, and continuous high-speed rotation. Centrifugal force, vibration, and fluid loads can cause deformation, cracks, corrosion, and even fracture of turbine components, posing safety hazards. Dynamic strain is an important indicator reflecting the local characteristics of turbine rotors and can be used for health monitoring and fault early warning of turbine rotor structures. Therefore, research on rotor surface strain sensing methods is of great significance.

[0003] Strain measurement of rotating structures faces two major challenges: signal sensing and signal transmission. Traditional resistance methods employ resistance strain gauges for sensing, combined with slip rings to extract signals from the rotating end. While electrical measurement methods are relatively mature, resistance strain gauges have short lifespans at high temperatures and are susceptible to electromagnetic interference. Furthermore, the noise generated by the friction between the slip ring brush and the slip ring further reduces demodulation accuracy. These characteristics limit the application of resistance methods in high-temperature, high-interference environments.

[0004] Fiber optic sensing technology is characterized by its small size, light weight, and resistance to electromagnetic interference, making it more suitable for strain sensing in special environments. Fiber optic sensing technology is divided into fiber optic grating sensing and fiber optic Fabry-Perot sensing. Fiber optic grating structures experience performance degradation after prolonged operation at temperatures exceeding 1000℃, rendering them unsuitable for long-term operation, and they also suffer from temperature-strain cross-sensitivity issues. Fiber optic Fabry-Perot sensors, on the other hand, reflect temperature and strain changes in the measured structure through variations in cavity length. Sapphire Fabry-Perot sensors, in particular, can withstand temperatures exceeding 1200℃ and can address the issues of high-temperature performance degradation and cross-sensitivity.

[0005] For signal transmission in fiber optic Fabry-Perot sensors, smooth ring structures are currently the primary method used both domestically and internationally. While smooth ring structures offer resistance to electromagnetic interference, high transmission rates, and long service lives, they are also complex, expensive, and require withstanding significant impact loads at high speeds, leading to increased insertion loss. Therefore, smooth ring structures are insufficient to meet the signal transmission requirements at high speeds. Summary of the Invention

[0006] The purpose of this invention is to provide a split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, including a blackbody light source, a fiber optic Fabry-Perot sensor, a fiber optic collimator, a surface-type optical wedge, a surface-array infrared detector, and a signal processing module.

[0007] The blackbody light source undergoes spontaneous blackbody radiation at high temperature, causing the incident light to couple from the end face of the optical fiber into the fiber optic Fabry-Perot sensor.

[0008] The fiber optic Fabry-Perot sensor is attached to the surface of the structure being measured and transmits the Fabry-Perot light signal containing strain information into the optical fiber.

[0009] The fiber collimator collimates the Fabry-Perot light signal into a parallel light signal, which is then emitted into free space.

[0010] The surface-shaped optical wedge receives the parallel optical signal and demodulates it to obtain a demodulated optical signal;

[0011] The area array infrared detector collects and demodulates optical signals, generates a two-dimensional image, and transmits it to the signal processing module;

[0012] The signal processing module processes the two-dimensional image to obtain the cavity length of the fiber optic Fabry-Perot sensor.

[0013] Furthermore, the fiber optic Fabry-Perot sensor is an intrinsic Fabry-Perot sensor made of sapphire fiber.

[0014] Furthermore, the surface-shaped optical wedge is an air-cavity optical wedge, with the thickness of the optical wedge continuously varying along the horizontal x-direction and remaining constant along the horizontal y-direction.

[0015] Each pixel in a two-dimensional image corresponds to a thickness value of the optical wedge, generating a demodulated optical signal.

[0016] Furthermore, the area array infrared detector generates an index number for each pixel while generating a two-dimensional image; the pixel index number is related to the thickness of the optical wedge corresponding to that pixel.

[0017] Furthermore, the relationship between the pixel index number and the thickness of the corresponding light wedge is as follows:

[0018] h=h0+xstanθ (1)

[0019] In the formula, θ is the tilt angle of the optical wedge, x is the index number of the infrared array detector along the direction of optical wedge thickness change, s is the pixel size, h0 is the optical wedge thickness corresponding to index number 0, and h is the optical wedge thickness corresponding to index number x.

[0020] Furthermore, the signal processing module performs the following steps to process the two-dimensional image:

[0021] 1) Perform analog-to-digital conversion on the two-dimensional image to obtain a digital signal;

[0022] 2) The digital signal is windowed and truncated to obtain a two-dimensional light intensity signal array I(x,y);

[0023] 3) Integrate and accumulate the light intensity values ​​of the two-dimensional light intensity signal column by column to transform the two-dimensional light intensity array I(x,y) into a one-dimensional array I1(x);

[0024] 4) Perform peak analysis on the one-dimensional array I1(x) to find the index number i corresponding to the maximum value I1(i) in the one-dimensional array I1(x);

[0025] 5) Based on the correspondence between pixel index number i and optical wedge thickness h, determine the optical wedge thickness corresponding to the position of the maximum value of light intensity integral, and use this optical wedge thickness as the cavity length L of the Fabry sensor.

[0026] Furthermore, the intensity E(λ,T) of the spontaneous emission from the blackbody source is shown below:

[0027]

[0028] In the formula, ε(λ) is the effective emission coefficient of the cavity, h' is Planck's constant, λ is the wavelength, c is the speed of light, and K B is Boltzmann's constant, and T is the thermodynamic temperature.

[0029] Furthermore, the intensity I of the transmitted light from the Fabry-Perot lamp. T (λ) is shown below:

[0030]

[0031] In the formula, R is the reflectivity of the fiber end face, L is the cavity length of the Fabry-Perot sensor, and n represents the refractive index inside the optical wedge.

[0032] Furthermore, the two-dimensional intensity distribution I(x,y) of the demodulated optical signal is shown below:

[0033]

[0034] In the formula, R1 and R2 are the reflectivities of the upper and lower surfaces of the optical wedge; (x,y) are the position coordinates of the CCD surface; h(x) is the thickness of the optical wedge corresponding to point (x,y); (x p ,y p B represents the position of the center point of the two-dimensional Gaussian spot. x and B y λ represents the standard deviation of the Gaussian distribution of the light spot along the x-axis and y-axis, respectively; when the thickness of the optical wedge is equal to the length of the Fabry-Perot cavity, the two-dimensional intensity distribution I(x,y) of the demodulated optical signal reaches its maximum value. max , λ min These are the upper and lower limits of the wavelength;

[0035] The technical effects of this invention are undeniable, and its beneficial effects are as follows:

[0036] 1) Fiber optic Fabry-Perot is used for strain sensing in high-temperature turbine rotor systems. The sensor is small in size, has strong anti-electromagnetic interference capability, and high transmission rate.

[0037] 2) The cavity length signal is extracted by free space coupling, avoiding the impact load and insertion loss caused by using slip ring structure for physical connection;

[0038] 3) The light source and sensor are integrated, and the sensing end and demodulation end are spatially independent. This transmissive Fabry-Perot structure improves the light intensity and avoids the light intensity loss caused by the bidirectional coupling of the reflective structure.

[0039] 4) The lateral jitter of the light spot in this invention has a low impact on demodulation.

[0040] This invention directly uses a surface-shaped optical wedge and an area array detector as demodulation elements. The lateral jitter of the rotating shaft only causes the position of the light spot to shift, without affecting the relative light intensity distribution of the light spot, thus reducing the impact on demodulation. Attached Figure Description

[0041] Figure 1 This is a schematic diagram showing the relative coordinate positions of the surface-shaped optical wedge and the area array infrared detector;

[0042] Figure 2 (a) is a simulation diagram of the light spot intensity distribution collected by the area array infrared detector. Figure 2 (b) is a simulation diagram of the result of integrating the spot intensity distribution along the y-axis;

[0043] Figure 3 A schematic diagram of a turbine rotor dynamic strain measurement system provided in an embodiment of the present invention;

[0044] In the figure, the structure under test is 1, blackbody light source is 2, sensor head is 3, sapphire fiber is 4, fiber collimator is 5, area array infrared detector is 6, area type optical wedge is 7, and signal processing module is 8. Detailed Implementation

[0045] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0046] Example 1:

[0047] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system includes a blackbody light source 2, a fiber optic Fabry-Perot sensor, a fiber optic collimator 5, a surface-type optical wedge 7, a surface-array infrared detector 6, and a signal processing module 8.

[0048] The blackbody light source 2 undergoes spontaneous blackbody radiation at high temperature, causing the incident light to couple from the end face of the optical fiber into the fiber optic Fabry-Perot sensor.

[0049] The fiber optic Fabry-Perot sensor is attached to the surface of the structure under test 1 and transmits the Fabry-Perot light signal containing strain information into the optical fiber.

[0050] The fiber collimator 5 collimates the Fabry-Perot light signal into a parallel light signal, which is then emitted into free space.

[0051] The surface-shaped optical wedge 7 receives the parallel optical signal and demodulates it to obtain a demodulated optical signal;

[0052] The area array infrared detector 6 collects demodulated light signals, generates a two-dimensional image, and transmits it to the signal processing module 8;

[0053] The signal processing module 8 processes the two-dimensional image to obtain the cavity length of the fiber optic Fabry-Perot sensor.

[0054] Example 2:

[0055] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with the same technical content as in Embodiment 1, further wherein the fiber optic Fabry-Perot sensor is an intrinsic Fabry-Perot sensor made of sapphire fiber.

[0056] Example 3:

[0057] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with technical content identical to any one of embodiments 1-2, and further, as... Figure 1 As shown, the surface-shaped optical wedge 7 is an air cavity optical wedge, and the thickness of the optical wedge changes continuously along the horizontal x-direction and remains constant along the horizontal y-direction.

[0058] Example 4:

[0059] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with the same technical content as any one of embodiments 1-3, further wherein each pixel of the two-dimensional image corresponds to a demodulated optical signal generated by a thickness value of the optical wedge.

[0060] Example 5:

[0061] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with the same technical content as any one of embodiments 1-4, further wherein the area array infrared detector 6 generates an index number for each pixel while generating a two-dimensional image; the pixel index number is related to the thickness of the optical wedge corresponding to that pixel.

[0062] Example 6:

[0063] See Figures 1 to 3A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with technical content identical to any one of embodiments 1-5, further wherein the correlation between the pixel index number and the thickness of the corresponding optical wedge is as follows:

[0064] h=h0+xstanθ(1)

[0065] In the formula, θ is the tilt angle of the optical wedge, x is the index number of the infrared array detector along the direction of optical wedge thickness change, s is the pixel size, h0 is the optical wedge thickness corresponding to index number 0, and h is the optical wedge thickness corresponding to index number x.

[0066] Example 7:

[0067] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with technical content identical to any one of embodiments 1-6, further comprising the following steps for the signal processing module 8 to process the two-dimensional image:

[0068] 1) Perform analog-to-digital conversion on the two-dimensional image to obtain a digital signal;

[0069] 2) The digital signal is windowed and truncated to obtain a two-dimensional light intensity signal array I(x,y);

[0070] 3) Integrate and accumulate the light intensity values ​​of the two-dimensional light intensity signal column by column to transform the two-dimensional light intensity array I(x,y) into a one-dimensional array I1(x);

[0071] 4) Perform peak analysis on the one-dimensional array I1(x) to find the index number i corresponding to the maximum value I1(i) in the one-dimensional array I1(x);

[0072] 5) Based on the correspondence between pixel index number i and optical wedge thickness h, determine the optical wedge thickness corresponding to the position of the maximum value of light intensity integral, and use this optical wedge thickness as the cavity length L of the Fabry sensor.

[0073] Example 8:

[0074] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with technical content identical to any one of embodiments 1-7, further wherein the spontaneous emission intensity E(λ,T) of the blackbody light source 2 is as follows:

[0075]

[0076] In the formula, ε(λ) is the effective emission coefficient of the cavity, h' is Planck's constant, λ is the wavelength, c is the speed of light, and K B is Boltzmann's constant, and T is the thermodynamic temperature.

[0077] Example 9:

[0078] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with technical content identical to any one of embodiments 1-8, further wherein the intensity I of the Fabry-Perot transmitted light... T (λ) is shown below:

[0079]

[0080] In the formula, R is the reflectivity of the fiber end face, and L is the cavity length of the Fabry-Perot sensor. n represents the refractive index inside the optical wedge. The refractive index inside the air cavity optical wedge is n = 1.

[0081] Example 10:

[0082] See Figures 1 to 3 A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with the same technical content as any one of embodiments 1-9, further wherein the two-dimensional light intensity distribution I(x,y) of the demodulated optical signal is as follows:

[0083]

[0084] In the formula, R1 and R2 are the reflectivities of the upper and lower surfaces of the optical wedge; (x,y) are the position coordinates of the CCD surface; h(x) is the thickness of the optical wedge corresponding to point (x,y); (x p ,y p B represents the position of the center point of the two-dimensional Gaussian spot. x and B y λ represents the standard deviation of the Gaussian distribution of the light spot along the x-axis and y-axis, respectively; when the thickness of the optical wedge is equal to the length of the Fabry-Perot cavity, the two-dimensional intensity distribution I(x,y) of the demodulated optical signal reaches its maximum value. max , λ min These are the upper and lower limits of the wavelength;

[0085] Example 11:

[0086] A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, with the same technical content as any one of embodiments 1-10, wherein the fiber optic Fabry-Perot sensor includes a sensing head 3 and a sapphire fiber 4.

[0087] Example 12:

[0088] A split-type fiber optic sensing system for dynamic strain in a high-temperature turbine rotor system, such as Figure 3 As shown, it includes: a blackbody light source, a sensor head, an optical fiber collimator, a surface-type optical wedge, a surface-array infrared detector, and a computer.

[0089] When the turbine disk rotates in a high-temperature environment, the blackbody cavity bonded to the surface of the disk by high-temperature adhesive generates spontaneous radiation, and the blackbody radiation light is coupled into the sapphire optical fiber.

[0090] The Fabry-Perot cavity sensor detects structural strain, and the cavity length changes accordingly. The transmitted light from the sensor carries information about the Fabry-Perot cavity length.

[0091] After the transmitted light from the fiber end exits the Fabry-Perot cavity, the fiber collimator collimates it into a parallel spot, which is then emitted into free space.

[0092] Parallel light spots are incident perpendicularly onto a surface-shaped light wedge. The transmitted and reflected light from the surface-shaped light wedge undergo correlation interference, and a grayscale image of the correlation interference light is captured by an array infrared detector.

[0093] After the image data is converted from digital signal to digital signal, it is sent to the host computer for processing to obtain two-dimensional data I(x,y) of the intensity distribution of the relevant interference light. The host computer program integrates the two-dimensional data along the y-axis to obtain a one-dimensional integral array I1(x). Then, peak finding is performed on I1(x) to find the index number i corresponding to the maximum point I(i) of the one-dimensional array. Using the correspondence between the index number and the wedge thickness h(x), the wedge thickness h(i) corresponding to i can be found. This thickness is the cavity length value of the fiber optic Fabry-Perot sensor under test.

[0094] In actual measurement using the demodulation system, it is difficult to guarantee that the zero point of the optical wedge and the area array detector will perfectly coincide, and the minimum thickness of the optical wedge cannot be guaranteed to be zero. If L0 is the optical wedge thickness corresponding to the first pixel, L is the cavity length of the fiber Fabry-Perot sensor under test, θ is the wedge tilt angle, i is the index number corresponding to the maximum value of the light intensity integral, and s is the pixel size, then the cavity length can be calculated as: L = L0 + istanθ. In this formula, L0 is an unknown quantity, which can be obtained by calibration using a Fabry-Perot sensor with a known cavity length.

[0095] Example 13:

[0096] A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system includes a blackbody light source, a sapphire fiber optic Fabry-Perot sensor, a fiber optic collimator, a surface-type optical wedge, a surface-array infrared detector, and a signal processing module.

[0097] The functions of each part of the measurement system are:

[0098] The blackbody light source is the light source of the measurement system. It generates spontaneous blackbody radiation at high temperature, and the incident light is coupled from the end face of the optical fiber into the sapphire optical fiber.

[0099] The sensing head is a fiber optic Fabry-Perot strain sensor, which is bonded to the surface of the structure being measured.

[0100] The fiber collimator is connected to a multimode fiber and collimates the Fabry-Perot transmitted light spot emitted from the fiber end into parallel light, which is then emitted into free space.

[0101] The surface-shaped optical wedge is a hardware-related demodulation element used to demodulate optical signals containing strain information;

[0102] The area array infrared detector is a light signal acquisition element used to detect a two-dimensional image of the light output by the area-shaped light wedge;

[0103] The signal processing module processes the two-dimensional image acquired by the array infrared detector to obtain the cavity length of the Fabry-Perot cavity sensor.

[0104] The signal processing module processes the two-dimensional image using the following steps:

[0105] (1) Convert the acquired analog images into digital signals through analog-to-digital conversion;

[0106] (2) Acquire the converted digital signal and window it to obtain a two-dimensional light intensity signal array I(x,y);

[0107] (3) Integrate and accumulate the light intensity values ​​of the two-dimensional light intensity signal column by column to transform the two-dimensional light intensity array I(x,y) into a one-dimensional array I1(x);

[0108] (4) Perform peak analysis on the one-dimensional array I1(x) obtained by integration to find the index number i corresponding to the maximum value of the one-dimensional array;

[0109] (5) By using the correspondence between the pixel index number i of the area array detector and the wedge thickness h of the optical wedge, the optical wedge thickness corresponding to the position of the maximum value of the light intensity integral can be found. This thickness is the cavity length L of the Fabry sensor.

[0110] The basic principle of optical signal cavity length demodulation is as follows: the light intensity distribution of the light spot received by the area CCD array changes with the Fabry-Perot cavity length, and the thickness of the optical wedge corresponding to the maximum light intensity is the Fabry-Perot cavity length. Generally, the light intensity of spontaneous emission from a blackbody source can be expressed as:

[0111]

[0112] Where ε(λ) is the effective emission coefficient of the cavity, h is Planck's constant, λ is the wavelength, c is the speed of light, and K... B Let I be the Boltzmann constant and T be the thermodynamic temperature. The intensity of the transmitted signal from the FAPER cavity is I. T (λ) is:

[0113]

[0114] Where R is the reflectivity of the fiber end face and L is the cavity length of the Fabry-Perot sensor.

[0115] The relative coordinate positions of the optical wedge and the area array infrared detector are as follows: Figure 1 As shown, the surface-type optical wedge, used as a non-scanning correlation element, constructs a reference Fabry-Perot cavity structure with a cavity length that varies continuously in space. Its transmitted and reflected light undergo correlation interference, and the two-dimensional intensity distribution of the output light from the optical wedge is as follows:

[0116]

[0117] The exponential term represents the Gaussian distribution function of the beam in space, R1 and R2 are the reflectivities of the upper and lower surfaces of the optical wedge, h(x) is the thickness of the optical wedge at that point, and (x,y) are the position coordinates of the CCD surface. When the thickness of the optical wedge is equal to the length of the Fabry-Perot cavity, the integral expression reaches its maximum value, and the distribution simulation of I(x,y) is as follows: Figure 2 As shown in (a).

[0118] like Figure 1 As shown, the thickness of the optical wedge remains constant along the y-axis. Integrating the acquired two-dimensional array of light intensity along the y-axis transforms the two-dimensional distribution into a one-dimensional distribution. The simulation graph of the integration result is shown below. Figure 2 As shown in (b), the thickness of the optical wedge corresponding to the pixel at the maximum light intensity is the demodulation value of the cavity length.

[0119] The relationship between the pixel index number and the optical wedge thickness can be determined through calibration experiments. The formula is L = L0 + istanθ. In this formula, L0 is the optical wedge thickness corresponding to the first pixel, L is the cavity length of the fiber optic Fabry-Perot sensor under test, θ is the wedge tilt angle, i is the index number corresponding to the maximum value of the light intensity integral, and s is the pixel size. Since L0 is an unknown quantity, it can be calculated directly by calibrating the corresponding index number using a Fabry-Perot sensor with a known cavity length.

Claims

1. A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system, characterized in that: It includes a blackbody light source (2), a fiber optic Fabry-Perot sensor, a fiber optic collimator (5), a surface-type optical wedge (7), a surface-array infrared detector (6), and a signal processing module (8); The blackbody light source (2) generates spontaneous blackbody radiation at high temperature, causing the incident light to couple from the end face of the optical fiber into the fiber Fabry-Perot sensor; The fiber optic Fabry-Perot sensor is attached to the surface of the structure under test (1) and transmits the Fabry-Perot light signal containing strain information into the optical fiber; The fiber collimator (5) collimates the Fabry-Perot light signal into a parallel light signal, which is then emitted into free space. The surface-shaped optical wedge (7) receives the parallel optical signal and demodulates it to obtain a demodulated optical signal; The area array infrared detector (6) collects demodulated light signals, generates a two-dimensional image, and transmits it to the signal processing module (8). The signal processing module (8) processes the two-dimensional image to obtain the cavity length of the fiber optic Fabry-Perot sensor; Fabry-Perot transmitted light intensity As shown below: （3） In the formula, R is the reflectivity of the fiber end face, and L is the cavity length of the Fabry-Perot sensor; Let be Planck's constant. where λ is the wavelength, c is the speed of light, and K is the velocity. B is Boltzmann's constant, T is the thermodynamic temperature; n represents the refractive index inside the optical wedge; The two-dimensional intensity distribution of the demodulated optical signal As shown below: （4） In the formula, R1 and R2 are the reflectivities of the upper and lower surfaces of the optical wedge; (x,y) are the position coordinates of the surface of the area array infrared detector (6); h(x) is the thickness of the optical wedge corresponding to point (x,y); (x p ,y p B represents the position of the center point of the two-dimensional Gaussian spot. x and B y These are the standard deviations of the Gaussian distribution of the light spot along the x-axis and y-axis, respectively; It is the intensity of light transmitted through Fabry-Perot; Wavelength; These are the upper and lower limits of the wavelength; When the thickness of the optical wedge is equal to the length of the Fabry-Perot cavity, the two-dimensional intensity distribution of the demodulated optical signal is shown. To obtain the maximum value; The steps of the signal processing module (8) in processing the two-dimensional image include: Step 1) Perform analog-to-digital conversion on the two-dimensional image to obtain a digital signal; Step 2) Window the digital signal to obtain a two-dimensional light intensity signal array. ; Step 3) Integrate and accumulate the light intensity values ​​of the two-dimensional light intensity signal column by column, and then convert the two-dimensional light intensity signal array into a single array. Transform it into a one-dimensional array I1(x); Step 4) Perform peak analysis on the one-dimensional array I1(x) to find the index number i corresponding to the maximum value I1(i) in the one-dimensional array I1(x); Step 5) Based on the correspondence between pixel index number i and optical wedge thickness h, determine the optical wedge thickness corresponding to the position of the maximum value of light intensity integral, and use the optical wedge thickness as the cavity length L of the Fabry sensor.

2. The split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system according to claim 1, characterized in that: The fiber optic Fabry-Perot sensor is an intrinsic Fabry-Perot sensor made of sapphire fiber.

3. The split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system according to claim 1, characterized in that: The surface-shaped optical wedge (7) is an air cavity optical wedge, and the thickness of the optical wedge changes continuously along the horizontal x direction and remains unchanged along the horizontal y direction; Each pixel in a two-dimensional image corresponds to a thickness value of the optical wedge, generating a demodulated optical signal.

4. The split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system according to claim 3, characterized in that: The area array infrared detector (6) generates an index number for each pixel while generating a two-dimensional image; the pixel index number is related to the thickness of the optical wedge corresponding to that pixel.

5. A split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system according to claim 4, characterized in that: The relationship between pixel index number and the corresponding wedge thickness is shown below: （1） In the formula, The angle of the light wedge. s is the index number of the area array infrared detector along the direction of the optical wedge thickness change, h0 is the optical wedge thickness corresponding to index number 0, and h is the optical wedge thickness corresponding to index number x.

6. The split-type fiber optic sensing system for dynamic strain of a high-temperature turbine rotor system according to claim 1, characterized in that, Intensity of spontaneous emission from a blackbody light source (2) As shown below: （2） In the formula, The effective emission coefficient of the cavity, Let be Planck's constant. where λ is the wavelength, c is the speed of light, and K is the velocity. B is Boltzmann's constant, and T is the thermodynamic temperature.

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