Turbine blade film hole diameter non-contact measurement system and method

Abstract

The invention relates to the technical field of blade film hole measurement, in particular to a turbine blade film hole diameter non-contact measurement system and method. According to the technical scheme, the device comprises a tunable laser, a polarization controller, an optical fiber circulator, a vertical coupling echo wall microcavity, a photoelectric detector, a three-dimensional displacement device, turbine blades and a double-shaft turntable. Wherein the output end of the tunable laser is connected with the input end of the polarization controller. According to the invention, through the evanescent field sensitive characteristic of the sub-wavelength scale echo wall microcavity probe, the nanoscale precision non-contact measurement of the aperture of the turbine blade air film hole is realized, and the industrial measurement problem caused by contact damage, optical diffraction limitation and insufficient industrial CT precision of a micropore with a large depth-diameter ratio is solved in a breakthrough manner; on the premise of zero damage, the detection precision is improved to the nanometer level, and meanwhile, by means of a miniaturized optical fiber system and a double-shaft dynamic calibration structure, the complex deep hole detection cost is remarkably reduced, and second-level efficient measurement is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of blade film hole measurement, and particularly to a non-contact measurement system and method for the aperture of turbine blade film holes. Background Art

[0002] Aero-engines are known as the "pearl on the industrial crown", and their performance directly determines the thrust, fuel economy and reliability of aircraft. Turbine blades are one of the key components in the hot-end parts of aero-engines that bear the most severe loads and operate in the harshest environments. In order to operate reliably at continuously increasing turbine inlet temperatures, turbine blades widely adopt complex cooling structures. Among them, the film cooling technology forms a protective film on the blade surface by machining a large number of tiny film holes on the blade surface, isolating the high-temperature gas, thereby effectively reducing the blade surface temperature. Geometric parameters of the film holes such as aperture and position directly affect the cooling efficiency. Therefore, accurate and efficient measurement of the film hole aperture is a key link in blade manufacturing and quality control.

[0003] Current measurement technologies for the aperture of turbine blade film holes can be divided into two categories: contact measurement and non-contact measurement. Contact measurement technologies mainly rely on the direct contact between a probe and the film hole to obtain size information. A common one is a coordinate measuring machine, which scans the contour of the film hole through a precise probe to calculate the aperture size. Its advantages are high measurement accuracy and good repeatability; the disadvantage is that the probe contacting the measured surface may damage the film hole. Non-contact measurement technologies avoid contacting the film hole, thereby reducing the possibility of damage and improving the measurement efficiency. Common ones include optical microscopes and industrial CT. The advantage of an optical microscope is simple operation and low cost, but its accuracy is limited by optical diffraction and it is difficult to measure the aperture of tiny deep holes. Industrial CT can achieve non-destructive detection of the internal film holes of the blade and obtain three-dimensional topography information of the film holes, but the equipment cost is high and the measurement resolution is relatively low, usually above 10 μm. Therefore, in the face of increasingly demanding requirements for film hole aperture measurement, there is an urgent need for a non-contact measurement technology that can adapt to micro-holes with a large depth-to-diameter ratio. This application proposes a non-contact measurement system and method for the aperture of turbine blade film holes. Summary of the Invention

[0004] The purpose of the present invention is to address the problem in the background art that there is no non-contact measurement that can adapt to micro-holes with a large depth-to-diameter ratio, and to propose a non-contact measurement system and method for the aperture of turbine blade film holes.

[0005] In a first aspect, the present application provides a non-contact measurement system for the aperture of turbine blade film holes, including a tunable laser, a three-dimensional displacement device and a two-axis turntable. The output end of the tunable laser is connected to a polarization controller, and the output end of the polarization controller is connected to an optical fiber circulator; The through output end of the fiber optic circulator is connected to a vertically coupled whispering gallery microcavity, which is fixed on the three-dimensional displacement device, and the reflective output end of the fiber optic circulator is connected to a photodetector; A turbine blade is fixed on the two-axis turntable, and the two-axis turntable is used to adjust the spatial orientation of the turbine blade so that the axis of the air film hole coincides with the axis of the probe of the vertically coupled whispering gallery microcavity.

[0006] Optionally, the vertically coupled whispering gallery microcavity is formed by melting the end of a micro-nano fiber into a microsphere structure, the diameter of its probe is 0.3 - 2 μm, and the diameter of the microsphere is 0.01 - 1 mm.

[0007] Optionally, the vertically coupled whispering gallery microcavity is configured as: When the probe penetrates into the air film hole and the gap between the microsphere and the inner wall of the hole is at the sub-wavelength scale, its evanescent field is disturbed by the hole wall, resulting in a change in the characteristic parameters of the reflection spectrum.

[0008] Optionally, the characteristic parameters include at least one of the maximum reflectivity and the resonant wavelength.

[0009] Optionally, the diameter of the microsphere of the vertically coupled whispering gallery microcavity is 20 μm, and the diameter of the probe is 0.4 μm.

[0010] Optionally, the operating wavelength of the tunable laser is 1530 - 1536 nm, and the line width is 280 - 320 kHz.

[0011] Optionally, the photodetector is configured to: by monitoring the change amount of the characteristic parameters of the reflection spectrum, be used for the nano-level precision detection of the gap between the microsphere and the inner wall of the air film hole, and the gap value corresponding to the optimal interval of the detection sensitivity is 0.2 μm.

[0012] In a second aspect, the present application provides a non-contact measurement method for the aperture of the air film hole of a turbine blade, which is applied to a non-contact measurement system for the aperture of the air film hole of a turbine blade described in the first aspect, and includes the following steps: S1: Adjust the turbine blade through the two-axis turntable so that the axis of the air film hole coincides with the axis of the probe of the vertically coupled whispering gallery microcavity; S2: The tunable laser emits a laser with a continuously tunable wavelength, and after the polarization state is adjusted by the polarization controller, it is input into the fiber optic circulator; S3: The laser is input into the vertically coupled whispering gallery microcavity through the fiber optic circulator, and the light wave that satisfies the resonance condition forms a resonance in the microcavity, and the reflected light wave is transmitted to the photodetector through the fiber optic circulator; S4: The photodetector converts the reflected light wave into an electrical signal to obtain a reflection spectrum; S5: Under the control of the three-dimensional displacement device, drive the vertically coupled whispering gallery microcavity to move along the diameter direction of the air film hole to the first measurement position, and obtain the first gap between the microsphere and the inner wall of the hole. ; S6: Continue to drive the vertically coupled whispering gallery microcavity to move to the second measurement position opposite in the diameter direction, and obtain the second gap between the microsphere and the inner wall of the hole. ; S7: Calculate the aperture of the air film hole according to the formula : , where is the diameter of the microsphere, is the displacement of the probe in the diameter direction recorded by the three-dimensional displacement device.

[0013] Optionally, the acquisition of the first gap and the second gap specifically includes: Through the mapping relationship between the reflection spectrum characteristic parameters and the preset calibration curve, convert the maximum reflectivity change or resonance wavelength drift of the reflection spectrum into a gap value; The calibration curve is established by experimentally measuring the reflection spectrum characteristic parameters at different known gaps.

[0014] Optionally, the displacement in step S7 is measured with nanometer-level accuracy by a grating ruler or a laser interferometer built in the three-dimensional displacement device.

[0015] Compared with the prior art, the present application includes at least one of the following beneficial technical effects: The measurement scheme of the air film hole aperture of the turbine blade based on the whispering gallery microcavity adopted in the present invention is a non-contact measurement, avoiding the drawback that the contact force in contact measurement may damage the surface of the measured part; The gap between the whispering gallery microcavity and the inner wall of the air film hole in the present invention is realized by monitoring the characteristic parameters of the reflection spectrum, and the accuracy can reach the nanometer level, greatly improving the measurement accuracy; The whispering gallery microcavity in the present invention has an elongated probe structure, which is suitable for measuring the aperture of microholes with a large depth-to-diameter ratio, overcoming the problem that the traditional probe radius is too large to measure microholes; The measurement system in the present invention is easy to miniaturize, simple to manufacture, and low in cost.

[0016] The present invention realizes the non-contact measurement of the air film hole aperture of the turbine blade with nanometer-level accuracy through the evanescent field sensitive characteristics of the sub-wavelength scale whispering gallery microcavity probe, and breakthroughly solves the industry measurement problems of large depth-to-diameter ratio microholes caused by contact damage, optical diffraction limitation and insufficient accuracy of industrial CT. On the premise of zero damage, the detection accuracy is improved to the nanometer level. At the same time, with the help of the miniaturized optical fiber system and the biaxial dynamic calibration structure, the cost of complex deep hole detection is significantly reduced and the efficient measurement in seconds is realized. Description of the Drawings

[0017] Figure 1 A non-contact measurement system diagram of the aperture of the film cooling holes on a turbine blade is given; Figure 2 It is the distribution diagram of the resonant mode field of the vertically coupled whispering gallery mode microcavity; Figure 3 It is the reflection spectrum diagram of the vertically coupled whispering gallery mode microcavity; Figure 4 It is the distribution diagram of the resonant mode field when the vertically coupled whispering gallery mode microcavity is close to the inner wall of the film cooling hole; Figure 5 It is the reflection spectrum diagram of the vertically coupled whispering gallery mode microcavity at different gaps; Figure 6 It is the curve diagram of the change of the maximum reflectivity at different gaps; Figure 7 It is the curve diagram of the change of the resonant wavelength at different gaps.

[0018] Reference Signs: 1, tunable laser; 2, polarization controller; 3, fiber optic circulator; 4, vertically coupled whispering gallery mode microcavity; 5, photodetector; 6, three-dimensional displacement device; 7, turbine blade; 8, two-axis turntable. Detailed Embodiments

[0019] The technical solution of the present invention will be further described below in conjunction with the drawings and specific embodiments.

[0020] Embodiment Refer to Figure 1 As shown, a non-contact measurement system of the aperture of the film cooling holes on a turbine blade proposed by the present invention includes a tunable laser 1, a polarization controller 2, a fiber optic circulator 3, a vertically coupled whispering gallery mode microcavity 4, a photodetector 5, a three-dimensional displacement device 6, a turbine blade 7, and a two-axis turntable 8.

[0021] Among them, the output end of the tunable laser 1 is connected to the input end of the polarization controller 2. The tunable laser 1 is used to generate a laser with continuously tunable wavelength and input it into the polarization controller 2; the output end of the polarization controller 2 is connected to the input end of the fiber optic circulator 3. The polarization controller 2 is used to adjust the polarization state of the laser light wave and input it into the fiber optic circulator 3.

[0022] In addition, the through output end of the optical fiber circulator 3 is connected to the input end of the vertical coupling whispering gallery microcavity 4, and the reflection output end of the optical fiber circulator 3 is connected to the input end of the photodetector 5. The optical fiber circulator 3 is used to transmit the laser light wave into the vertical coupling whispering gallery microcavity 4 and input the laser light wave reflected back from the vertical coupling whispering gallery microcavity 4 into the photodetector 5. The vertical coupling whispering gallery microcavity 4 is used to generate laser resonance and reflect the resonant light wave signal back to the optical fiber circulator 3. The vertical coupling whispering gallery microcavity 4 is directly fabricated on the micro-nano optical fiber and has a microsphere structure, which is convenient for detecting the pore wall deep in the micropore.

[0023] In this embodiment, the photodetector 5 is used to convert the reflected laser into an electrical signal, and then obtain the reflection spectrum. The three-dimensional displacement device 6 is implemented by a high-precision nano translation stage to accurately obtain the displacement of the vertical coupling whispering gallery microcavity 4. The vertical coupling whispering gallery microcavity 4 is fixed on the three-dimensional displacement device 6 and can achieve high-precision three-dimensional displacement.

[0024] It is worth noting that the turbine blade 7 is fixed on the two-axis turntable 8 to ensure that the film hole on the turbine blade 7 can be adjusted to be coaxial with the vertical coupling whispering gallery microcavity 4. In this embodiment, the working wavelength of the tunable laser 1 is near 1533 nm, and the line width is 300 kHz. The diameter of the microsphere of the vertical coupling whispering gallery microcavity 4 is 20 μm, the diameter of the probe is 0.4 μm, and the microsphere is obtained by arc discharge. Before measurement, the film hole is adjusted to be coaxial with the probe on the vertical coupling whispering gallery microcavity 4 by using the two-axis turntable 8.

[0025] Furthermore, the laser with continuously changing wavelength emitted from the tunable laser 1 enters the optical fiber circulator 3 after the polarization state is adjusted by the polarization controller 2, and then enters the vertical coupling whispering gallery microcavity 4. The light waves that meet the resonance conditions form resonance in the microsphere cavity and are strengthened, as Figure 2 shown, and a part of the light waves are reflected back to the optical fiber circulator 3. The light waves that do not meet the resonance conditions will be scattered to the outside and cannot be reflected, which is manifested as a peak in the reflection spectrum, as Figure 3As shown, it is a resonant mode. The characteristic parameters of this peak, such as the maximum reflectivity or the resonant wavelength, are affected by the gap between the vertically coupled whispering gallery microcavity 4 and the inner wall of the air film hole of the turbine blade 7. The change of the gap will cause the change of the characteristic parameters of the reflection spectrum. Therefore, by monitoring the characteristic parameters of the reflection spectrum, the gap between the vertically coupled whispering gallery microcavity 4 and the inner wall of the air film hole of the turbine blade 7 can be obtained, and the accuracy reaches the nanometer level. In the non-contact case, by moving the vertically coupled whispering gallery microcavity 4 along the diameter direction of the air film hole, the sizes of the two gaps between the vertically coupled whispering gallery microcavity 4 and the inner wall of the air film hole at both ends of the diameter are obtained respectively, and then the diameter of the microsphere and the displacement are superimposed to obtain the aperture value of the air film hole, thus solving the problem of difficult non-contact high-precision measurement of the aperture of micro-holes with a large depth-diameter ratio in the prior art.

[0026] As Figure 4 shown is the field distribution of the resonant mode when the vertically coupled whispering gallery microcavity 4 approaches the inner wall of the air film hole in this embodiment. The gap between the two is denoted as d. It can be seen that the inner wall of the air film hole has an obvious influence on the evanescent field.

[0027] As Figure 5 shown are the reflection spectra of the vertically coupled whispering gallery microcavity at different gaps. It can be seen that the slight change of the gap has a relatively obvious influence on the reflection spectrum. As the gap decreases, the maximum reflectivity of the reflection spectrum gradually decreases, and at the same time, the resonant wavelength also gradually decreases.

[0028] To more intuitively see the variation law of the characteristic parameters of the resonant mode with the gap, as Figure 6 and Figure 7 shown, the curves of the maximum reflectivity and the resonant wavelength of the reflection spectrum changing with the gap are given respectively. It can be seen that both the maximum reflectivity and the resonant wavelength decrease as the gap decreases. The change sensitivity of the maximum reflectivity basically remains unchanged, while the change sensitivity of the resonant wavelength gradually increases.

[0029] In order to maximize the non-contact measurement accuracy of the aperture of the air film hole of the turbine blade based on the whispering gallery microcavity proposed by the present invention, the detected value of the gap d between the vertically coupled whispering gallery microcavity 4 and the inner wall of the air film hole needs to be set in the region with the highest sensitivity. Although Figure 7 shows that the change sensitivity of the resonant wavelength keeps increasing as the gap decreases, when the gap is too small, it will cause the peak of the reflection spectrum to broaden and the peak value to decrease (as Figure 5 ), thus resulting in a decrease in the extraction accuracy of the resonant wavelength. Therefore, considering both the sensitivity and the peak parameter extraction accuracy, the detected value of the gap d is set to 0.2 μm, as shown by the vertical dashed lines in Figure 6 and Figure 7 . The probe diameter of the vertically coupled whispering gallery microcavity 4 of the present invention is 0.3 - 2 μm, and the diameter of the microsphere on the vertically coupled whispering gallery microcavity 4 is 0.01 - 1 mm; The above embodiments of the present invention provide a non-contact measurement system for the aperture of the film cooling holes of a turbine blade. Based on the principle of the interaction between the evanescent field of a whispering gallery microcavity and external substances, and using the characteristic that the change in the gap between the external substance and the whispering gallery microcavity will cause a change in the characteristic parameters of the resonance mode, by monitoring the maximum reflectivity and resonance wavelength of the resonance mode in the reflection spectrum, the monitoring of the gap between the vertical-coupling whispering gallery microcavity 4 and the inner wall of the film cooling hole 7 of the turbine blade is realized; under the control of the three-dimensional displacement device 6, the vertical-coupling whispering gallery microcavity 4 is moved along the diameter direction of the film cooling hole, and the gaps between the vertical-coupling whispering gallery microcavity 4 and the inner wall of the film cooling hole at both ends of the diameter of the film cooling hole are measured respectively; the sum of the two end gaps, the diameter of the microsphere and the displacement amount can obtain the aperture of the film cooling hole.

[0030] The above is an embodiment of the non-contact measurement system for the aperture of the film cooling holes of a turbine blade based on a whispering gallery microcavity of the present invention. The following is an embodiment of a non-contact measurement method for the aperture of the film cooling holes of a turbine blade of the present invention.

[0031] The embodiment of the present invention also provides a non-contact measurement method for the aperture of the film cooling holes of a turbine blade, which is applied to the above non-contact measurement system for the aperture of the film cooling holes of a turbine blade, and includes the following steps: S1: Adjust the turbine blade 7 through the two-axis turntable 8 so that the axis of the film cooling hole coincides with the probe axis of the vertical-coupling whispering gallery microcavity 4; S2: The tunable laser 1 emits a laser with continuously tunable wavelength, and after the polarization state is adjusted by the polarization controller 2, it is input into the fiber optic circulator 3; S3: The laser is input into the vertical-coupling whispering gallery microcavity 4 through the fiber optic circulator 3, and the light waves that meet the resonance condition form resonance in the microcavity, and the reflected light waves are transmitted to the photodetector 5 through the fiber optic circulator 3; S4: The photodetector 5 converts the reflected light wave into an electrical signal to obtain a reflection spectrum; S5: Under the control of the three-dimensional displacement device 6, drive the vertical-coupling whispering gallery microcavity 4 to move along the diameter direction of the film cooling hole to the first measurement position, and obtain the first gap between the microsphere and the inner wall of the hole ; S6: Continue to drive the vertical-coupling whispering gallery microcavity 4 to move to the second measurement position opposite in the diameter direction, and obtain the second gap between the microsphere and the inner wall of the hole ; The obtaining of the first gap and the second gap specifically includes: through the mapping relationship between the characteristic parameters of the reflection spectrum and the preset calibration curve, converting the change amount of the maximum reflectivity or the resonance wavelength drift amount of the reflection spectrum into a gap value; the calibration curve is established by experimentally measuring the characteristic parameters of the reflection spectrum at different known gaps; S7: Calculate the aperture of the film cooling hole according to the formula : , where is the diameter of the microsphere, The displacement of the probe in the diameter direction recorded by the three-dimensional displacement device 6. The displacement ΔL is measured by a grating scale or a laser interferometer built in the three-dimensional displacement device 6.

[0032] Through the sub-wavelength evanescent field sensitive characteristics of the vertically coupled whispering gallery microcavity (probe diameter 0.3 - 2 μm), the present invention breaks through the size limit of traditional contact probes (such as CMM) and the optical diffraction limit (such as microscopes), realizes non-destructive measurement of air film holes with a depth-to-diameter ratio > 10:1, and avoids the risk of contact damage.

[0033] Utilizing the nano-scale sensitivity of the microcavity reflection spectrum characteristic parameters (maximum reflectivity / resonant wavelength) to the gap, the present invention improves the gap detection accuracy to the nano-scale (optimal range 0.2 μm), which is two orders of magnitude higher than that of industrial CT (resolution about 10 μm). By combining a microsphere with a diameter of 0.01 - 1 mm and an ultra-fine probe, it can penetrate into the internal curved channels of turbine blades. The biaxial turntable dynamically adjusts the blade pose to ensure the precise alignment of the microcavity with the axis of the air film hole, overcoming the problem that traditional equipment cannot locate deep holes.

[0034] The present invention does not require a complex optical path. All components are connected by optical fibers, which are resistant to environmental interference and easy to encapsulate; calibration-free algorithm: the aperture is directly output through the superposition operation of the displacement ΔL (recorded by the nano translation stage) and the gap value (formula: ), reducing the manual calibration link. Only two displacement positionings (at both ends of the diameter) are required for a single measurement. Combined with the real-time analysis of the high-sensitivity reflection spectrum, the measurement period is shortened to the second level, and the efficiency is greatly improved compared with industrial CT (which requires three-dimensional scanning and reconstruction).

[0035] The above specific embodiments are merely several alternative embodiments of the present invention. Based on the technical solution of the present invention and the relevant revelations of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A non-contact measurement system for the aperture of a turbine blade film cooling hole, characterized in that, It includes a tunable laser (1), a three-dimensional displacement device (6) and a two-axis turntable (8). The output end of the tunable laser (1) is connected with a polarization controller (2), and the output end of the polarization controller (2) is connected with an optical fiber circulator (3); The direct output end of the optical fiber circulator (3) is connected with a vertically coupled whispering gallery microcavity (4), the vertically coupled whispering gallery microcavity (4) is fixed on the three-dimensional displacement device (6), and the reflected output end of the optical fiber circulator (3) is connected with a photodetector (5); A turbine blade (7) is fixed on the two-axis turntable (8), and the two-axis turntable (8) is used to adjust the spatial orientation of the turbine blade (7) so that the axis of the air film hole coincides with the probe axis of the vertically coupled whispering gallery microcavity (4); The vertically coupled whispering gallery microcavity (4) is formed by melting the end of a micro-nano optical fiber into a microsphere structure, its probe diameter is 0.3 - 2 μm, and the microsphere diameter is 0.01 - 1 mm; The vertically coupled whispering gallery microcavity (4) is configured as: When the probe penetrates into the air film hole and the gap between the microsphere and the inner wall of the hole is at the sub-wavelength scale, its evanescent field is disturbed by the hole wall, resulting in a change in the characteristic parameters of the reflection spectrum.

2. The non-contact measurement system for the aperture of the gas film holes of a turbine blade according to claim 1, wherein The characteristic parameters include at least one of the maximum reflectivity and the resonant wavelength.

3. The non-contact measurement system for the aperture of the film cooling holes of a turbine blade according to claim 1, wherein The microsphere diameter of the vertically coupled whispering gallery microcavity (4) is 20 μm, and the probe diameter is 0.4 μm.

4. A non-contact measurement system for the aperture of the gas film holes of a turbine blade according to claim 1, characterized in that, The working wavelength of the tunable laser (1) is 1530 - 1536 nm, and the line width is 280 - 320 kHz.

5. The non-contact measurement system for the aperture of the gas film hole of a turbine blade according to claim 1, characterized in that, The photodetector (5) is configured as: by monitoring the change amount of the characteristic parameters of the reflection spectrum, it is used for the nano-level precision detection of the gap between the microsphere and the inner wall of the air film hole, and the gap value corresponding to the optimal interval of the detection sensitivity is 0.2 μm.

6. A non-contact measurement method for the aperture of a turbine blade film cooling hole, which is applied to a non-contact measurement system for the aperture of a turbine blade film cooling hole according to any one of claims 1-5, characterized in that, It includes the following steps: S1: Adjust the turbine blade (7) through the two-axis turntable (8) to make the axis of the air film hole coincide with the probe axis of the vertically coupled whispering gallery microcavity (4); S2: The tunable laser (1) emits a laser with a continuously tunable wavelength, and after the polarization state is adjusted by the polarization controller (2), it is input into the optical fiber circulator (3); S3: The laser is input into the vertically coupled whispering gallery microcavity (4) through the optical fiber circulator (3), and the light waves that meet the resonance condition form resonance in the microcavity, and the reflected light waves are transmitted to the photodetector (5) through the optical fiber circulator (3); S4: The photodetector (5) converts the reflected light wave into an electrical signal to obtain a reflection spectrum; S5: Under the control of the three-dimensional displacement device (6), drive the vertically coupled whispering gallery microcavity (4) to move along the diameter direction of the air film hole to the first measurement position, and obtain the first gap between the microsphere and the inner wall of the hole ; S6: Continue to drive the vertically coupled whispering gallery microcavity (4) to move to the second measurement position opposite in the diameter direction, and obtain the second gap between the microsphere and the inner wall of the hole ; S7: Calculate the pore diameter of the gas film holes according to the formula : , where is the diameter of the microsphere, is the displacement of the probe in the diameter direction recorded by the three-dimensional displacement device (6).

7. A non-contact measurement method for the aperture of the film cooling holes of a turbine blade according to claim 6, characterized in that The first gap and the second gap are obtained specifically as follows: Through the mapping relationship between the characteristic parameters of the reflection spectrum and the preset calibration curve, the change amount of the maximum reflectivity or the drift amount of the resonant wavelength of the reflection spectrum is converted into a gap value; The calibration curve is established by experimentally measuring the characteristic parameters of the reflection spectrum at different known gaps.

8. A non-contact measurement method for the aperture of the film cooling holes of a turbine blade according to claim 6, characterized in that, The displacement amount described in step S7 is measured by the grating ruler or laser interferometer built in the three-dimensional displacement device (6).

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