Flow field surface pressure measuring method based on reflection spectrum

Abstract

The invention provides a flow field surface pressure measurement method based on a reflection spectrum, relates to the field of high-speed flow field pressure measurement, and solves the problems of low spatial resolution, damage to a flow field structure, weak anti-electromagnetic interference capability, poor stability and the like of an existing high-speed flow field pressure measurement technology. The method comprises the following steps: designing a one-dimensional grating waveguide structure device based on a grating abnormal phenomenon in a grating theory, and preparing the designed one-dimensional grating waveguide structure device; carrying out pressure calibration on the prepared one-dimensional grating waveguide structure device, placing the device into a test pressure measurement system of a high-speed flow field after calibration is completed, and carrying out flow field pressure measurement on the surface of the model through a reflection spectrum of the one-dimensional grating waveguide structure device; the grating structure is designed through the pressure sensitive mechanism of the flexible grating structure, real-time measurement of the high-speed flow field pressure is achieved through reflection spectrum frequency movement, interference to the flow field is small, electromagnetic interference to the environment is small, the device is simple, and the measurement and maintenance cost is low.

Description

Technical Field

[0001] The invention relates to the field of high-speed flow field pressure measurement, and in particular to a flow field surface pressure measurement method based on reflection spectroscopy. Background Art

[0002] With the development of aerospace engineering, the demand for accurate measurement of flow field pressure characteristics of high-speed aircraft is growing. This is not only crucial for the design and optimization of aircraft, but also the basis for ensuring its performance and safety. However, traditional pressure measurement technologies such as pressure hole method, pressure sensor method and pressure sensitive paint (PSP) method have exposed a series of technical bottlenecks and limitations when facing complex and changeable high-speed flow field environments.

[0003] Pressure hole method: This method measures pressure by drilling holes in the aircraft model and connecting pipes. However, this method destroys the original surface structure of the model and may change the fluid dynamics, thus affecting the measurement accuracy. In addition, due to the limited number of holes, it cannot provide sufficient spatial resolution, and the airflow conduction loss and signal hysteresis in the pipe limit the real-time and accuracy of the data.

[0004] Pressure sensor technology: Using micro-electromechanical system (MEMS) technology to install sensors on the model surface can improve measurement accuracy, but the high cost, complex structure and potential electromagnetic interference problems during the measurement process, coupled with the existence of measurement blind spots, make this method limited in fully covering high-speed flow fields.

[0005] Pressure-sensitive paint PSP technology: Although PSP provides high spatial resolution and little disturbance to the flow field, under high-speed flow conditions, the adverse pressure gradient formed on the surface of the model makes it difficult for oxygen molecules to reach the near-wall area, causing uneven oxygen distribution and resulting in measurement errors. PSP is also limited by the stability of the formula, fluorescence time, uniformity of the spray thickness, and short effective measurement time. These factors reduce the accuracy, reliability, and repeatability of the measurement, making it difficult to adapt to the needs of fine research on high-speed flow fields.

[0006] In view of the shortcomings and deficiencies of existing technologies, it is urgent to develop a new pressure measurement technology to overcome the above challenges and meet the high requirements of high-speed aircraft research on strong three-dimensional and unsteady flow field pressure measurement. Summary of the invention

[0007] Based on the current status of the background technology, the purpose of the present invention is to solve the problems of low spatial resolution, damage to flow field structure, weak anti-electromagnetic interference ability and poor stability of the existing high-speed flow field pressure measurement technology, and therefore proposes a flow field surface pressure measurement method based on reflection spectrum; the method uses flexible materials to develop pressure-sensitive grating devices, designs grating structures through the pressure-sensitive mechanism of flexible grating structures, and realizes real-time measurement of high-speed flow field pressure through reflection spectrum frequency shift. The present invention has little interference to the flow field, little environmental electromagnetic interference, simple device, and low measurement and maintenance costs.

[0008] The present invention adopts the following technical solutions to achieve the purpose: A method for measuring flow field surface pressure based on reflection spectroscopy, the method comprising the following steps: S1. Design one-dimensional grating waveguide structure device based on grating anomaly phenomenon in grating theory; S2. Prepare the designed one-dimensional grating waveguide structure device; S3. Perform pressure calibration on the prepared one-dimensional grating waveguide structure device, and after calibration, place it in the experimental pressure measurement system of the high-speed flow field; measure the flow field pressure on the model surface through the reflection spectrum of the one-dimensional grating waveguide structure device.

[0009] Furthermore, in step S1, the designed one-dimensional grating waveguide structure device includes a three-layer grating waveguide structure, which is a grating layer, a dielectric layer and a substrate from top to bottom; for the grating layer, it is designed as a one-dimensional grating structure arranged along the length direction of the one-dimensional grating waveguide structure device.

[0010] Furthermore, the material of the grating layer is the flexible material PMDS, and the materials of the dielectric layer and the substrate are both non-absorption dielectric materials; when the structural parameters of the grating layer made of the flexible material PMDS change, the resonant wavelength changes, resulting in a resonance anomaly phenomenon, which redistributes the light field energy and thereby changes the reflection spectrum of the one-dimensional grating waveguide structure device.

[0011] Furthermore, in step S2, when preparing the one-dimensional grating waveguide structure device, the non-absorbing medium material of the base adopts a silicon dioxide substrate; and the preparation process adopts a standard clean room semiconductor micro-nano processing process.

[0012] Furthermore, in step S3, when performing pressure calibration, the incident light is made to illuminate the one-dimensional grating waveguide structure device, so that the projection direction of the incident light on the horizontal plane is the same as the grating period length direction of the grating layer with a one-dimensional grating structure in the one-dimensional grating waveguide structure device; the pressure value is smoothly applied to the one-dimensional grating waveguide structure device, and the movement parameters of the reflection spectrum of the incident light after passing through the one-dimensional grating waveguide structure device at different pressure values ​​are recorded respectively as the calibration results of different pressure values.

[0013] Furthermore, the experimental pressure measurement system of the high-speed flow field includes a spectrometer, a reflector, an airflow space and a detector; when performing flow field pressure measurement, the aircraft model is placed in the airflow space, and the calibrated one-dimensional grating waveguide structure device is fixed on the surface of the aircraft model; the spectrometer is used to emit incident light with preset parameters, and the horizontal plane projection direction and the incident angle of the incident light are adjusted through the reflector so that the incident light illuminates the one-dimensional grating waveguide structure device; the detector is used to record the reflection spectrum generated by the incident light after passing through the one-dimensional grating waveguide structure device, and the reflection spectrum is compared with the calibration result to obtain the flow field surface pressure of the aircraft model in the current airflow space, thereby completing the flow field pressure measurement.

[0014] In summary, due to the adoption of this technical solution, the beneficial effects of the present invention are as follows: The one-dimensional grating waveguide structure device made by the present invention can be closely attached to the surface of the model without destroying the original structure of the model, avoiding interference with the flow field characteristics, and improving the accuracy and reliability of the measurement. By utilizing the frequency shift principle of the grating structure, the present invention can achieve rapid response and real-time monitoring of pressure changes in high-speed flow fields, overcome the problems of signal delay and attenuation in traditional methods, and improve the real-time and effectiveness of data.

[0015] The working mechanism of the grating device is not affected by the electromagnetic field, which enables the present invention to maintain stable performance in test scenarios with complex electromagnetic environments, ensuring the purity and consistency of the measured data. Compared with traditional MEMS sensor technology and PSP technology, the measurement process of the present invention will be simpler, without the need for complex pipelines or expensive material formulations, greatly reducing the purchase and maintenance costs of related equipment, and also reducing the complexity of operation.

[0016] Flexible grating devices can be flexibly arranged at any part of the model, including those surfaces with complex shapes or large curvatures, so as to make targeted pressure measurements and realize high-density, high-spatial-resolution pressure distribution measurement processes, so they are particularly suitable for analyzing the complex characteristics of strong three-dimensional and unsteady flow fields. The measurement technology of the present invention is also easy to integrate with existing test platforms, has good scalability, and can flexibly adjust the measurement range and accuracy according to different measurement requirements, providing strong technical support for future high-speed aircraft flow field research. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall process of the method of the present invention; Figure 2 It is a schematic structural diagram of a one-dimensional grating waveguide structure device in the present invention; Figure 3 A schematic diagram of the cross section and design parameters of a one-dimensional grating waveguide structure device in the present invention; Figure 4 A schematic diagram of the reflection spectrum of the device simulated and designed in the present invention under different pressures; Figure 5 One of the schematic diagrams showing the change of the resonance wavelength and peak value of the reflection spectrum with pressure; Figure 6 The second schematic diagram of the change of the resonance wavelength and peak value of the reflection spectrum with pressure; Figure 7 A schematic diagram of the preparation of a one-dimensional grating waveguide structure device in the present invention; Figure 8 It is a structural schematic diagram of the test pressure measurement system of the high-speed flow field in the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1 like Figure 1 As shown, a flow field surface pressure measurement method based on reflection spectroscopy, the overall process of the method can be summarized as the following steps: S1. Design one-dimensional grating waveguide structure device based on grating anomaly phenomenon in grating theory; S2. Prepare the designed one-dimensional grating waveguide structure device; S3. Perform pressure calibration on the prepared one-dimensional grating waveguide structure device, and after calibration, place it in the experimental pressure measurement system of the high-speed flow field; measure the flow field pressure on the model surface through the reflection spectrum of the one-dimensional grating waveguide structure device.

[0021] This embodiment will provide a detailed description of the design process of the one-dimensional grating waveguide structure device in step S1. First, a grating (also called a diffraction grating) is an optical element with a periodic structure, which modulates the amplitude or phase of the incident light through the periodic change of the refractive index field.

[0022] In grating theory, the phenomenon that the diffraction efficiency of a grating changes suddenly with the incident angle or wavelength is called grating anomaly. Based on this phenomenon, this embodiment designs a one-dimensional grating waveguide structure device with a three-layer grating waveguide structure. Figure 2 As shown, the one-dimensional grating waveguide structure device comprises a grating layer, a dielectric layer and a substrate from top to bottom; the grating layer is designed as a one-dimensional grating structure arranged along the length direction of the one-dimensional grating waveguide structure device.

[0023] In this embodiment, when designing a one-dimensional grating waveguide structure device, the material of the grating layer adopts the flexible material PMDS. The flexible material PMDS is a rubber material with high elasticity and transparency, and its operating temperature is between -50 ~ 200 ° C. It has a low Young's modulus, so it is often used for stretchable substrate materials. The Young's modulus of the flexible material PMDS used in this embodiment is 750kPa, and the Poisson's ratio is 0.49. For the dielectric layer and the substrate, the materials are all non-absorbent dielectric materials, and their Young's modulus is larger than that of the flexible material PMDS, so it can be considered as a non-stretchable material.

[0024] It can be known from the eigenvalue equation of the planar waveguide mode corresponding to the grating waveguide well known in the art that when the structural parameters of the grating layer of the flexible material PMDS change, the resonance wavelength changes, resulting in a resonance anomaly, which redistributes the light field energy and thus changes the reflection spectrum of the one-dimensional grating waveguide structure device. This is the theoretical basis for the design process of this embodiment.

[0025] Therefore, the design process of the one-dimensional grating waveguide structure device in this embodiment is as follows: like Figure 3 As shown, the material refractive index of the grating layer is determined , the material refractive index of the dielectric layer and the refractive index of the substrate material ; For a grating layer with a one-dimensional grating structure, determine the grating period , Fill Factor , and the central wavelength of the incident light required for the grating layer to work is recorded as , the incident angle is recorded as , so that the projection direction of the incident light on the horizontal plane is the same as the grating period length direction of the one-dimensional grating structure; Determine the thickness of the grating layer and the thickness of the dielectric layer , and set constraints on the refractive index: the material refractive index of the dielectric layer At the same time, it is greater than the refractive index of the material of the grating layer and the refractive index of the substrate material ; Then, based on the slab waveguide theory, the characteristic equations of the one-dimensional grating waveguide structure device in TE and TM modes are obtained:

[0026]

[0027] In the two characteristic equations, the three intermediate parameters , , ;in is the diffraction order, is the incident light wave vector, is the propagation constant; when the first Propagation constant of the evanescent wave and the dielectric layer The propagation constant of the waveguide mode When matching, The evanescent wave resonates with the guided mode in the dielectric layer, so that the energy of the incident light is effectively coupled to the waveguide mode, thereby obtaining the following formula:

[0028] In the formula, ; Thus, the design of one-dimensional grating waveguide structure devices is realized.

[0029] The TE mode (transverse electric mode) and TM mode (transverse magnetic mode) of the waveguide mentioned in the design process are the two basic modes of electromagnetic wave propagation in the waveguide structure. The TE mode is characterized by the electric field being confined within the cross section of the waveguide, while the magnetic field has components in the cross section and parallel to the propagation direction; the TM mode is characterized by the magnetic field being confined within the cross section of the waveguide, while the electric field has components in the cross section and parallel to the propagation direction.

[0030] The constant matching mentioned in the design process causes the guided mode to resonate, which is a resonance anomaly phenomenon (also called guided mode resonance), which is a type of grating anomaly. The principle of this phenomenon is the coupling of the grating diffraction wave with the leakage wave supported by the waveguide. It can be understood that when the phase of some diffraction waves in the grating matches the phase of the guided mode supported by the waveguide, the energy of the light field is redistributed. The guided mode resonance of the grating is a very special optical phenomenon with the characteristics of narrow bandwidth, high diffraction efficiency, wavelength sensitivity and angle sensitivity. It is often used to design high reflectors, refractive index detectors, narrowband filters, etc.; the design and measurement scenarios of this embodiment also utilize it.

[0031] Based on the design process of the one-dimensional grating waveguide structure device, as the preferred embodiment of this invention, the thin film anti-reflection layer design principle is adopted, the grating layer and the dielectric layer are designed as thin film structures, and the optical thickness of the thin film of the grating layer and the dielectric layer is selected to be the central wavelength of the incident light. ,Right now , is the equivalent refractive index of the grating layer.

[0032] After designing and optimizing, the specific design parameters of the three-layer grating waveguide structure of the optimal one-dimensional grating waveguide structure device are determined in this embodiment as follows: the central wavelength of the incident light , and TE polarization is used, that is, the direction of the electric field is parallel to the grating strips; the refractive index of the material of the grating layer ,thickness ; Material refractive index of the dielectric layer ,thickness ; Refractive index of the substrate material ; Grating period of the grating layer , filling factor .

[0033] Based on the above design parameters, this embodiment introduces the experimental situation of relevant data as follows.

[0034] Figure 4 is the reflection spectrum of the device grating structure under different pressures during the simulation process. Figure 4 It can be seen that at 0kPa pressure and 0° incident angle, the reflection spectrum is There is a strong reflection resonance peak at ; when the incident angle increases to 3°, The resonance peak at is split into and The splitting of the reflection peak with the incident angle can be explained by the grating theory. From the formula obtained by the energy coupling of the incident light at the above resonance, it can be seen that at normal incidence, Leaky wave corresponding to the evanescent wave and Leaky wave corresponding to the evanescent wave overlap and cannot be distinguished, which manifests as a strong reflection resonance peak; at oblique incidence, Leaky wave corresponding to the evanescent wave , The two resonance peaks appearing under oblique incidence are therefore two different leaky wave modes.

[0035] like Figure 4 As shown in FIG. 1 , when the pressure increases from 0 kPa to 200 kPa, the resonance modes in regions 1 and 2 in the figure are both red-shifted as the pressure increases, but the resonance intensity in region 1 decreases as the pressure increases, while the resonance intensity in region 2 remains unchanged; this is because when the incident angle, wavelength, and period are the same, the resonance mode increases as the equivalent refractive index of the grating increases. In the one-dimensional grating structure of the one-dimensional grating waveguide structure device designed in the above embodiment, the initial grating height, i.e., the thickness of the grating layer , width is the grating period Multiply by the fill factor for When the pressure increases, the equivalent refractive index of the grating layer increases with the width, and the corresponding resonance peak redshifts. The resonance intensity varies with the structure because the diffraction efficiency of the two modes is different in sensitivity to the grating height and width.

[0036] Figure 5 , Figure 6 The following figure shows the change of the resonance wavelength and peak value of the reflection spectrum with pressure. The two are in different wavelength ranges. It can be seen from the figure that the wavelengths of the two resonance peaks increase linearly with pressure. When the pressure increases from 0kPa to 200kPa, Figure 5 The resonant wavelength in Move to , wavelength shift ; Figure 6 The resonance wavelength From moving to , wavelength shift In addition, the resonance peaks of the two resonance modes vary differently with pressure, which is due to the different sensitivities of the different modes to the grating height and width.

[0037] Example 2 Based on Example 1, this example introduces in detail the preparation process of the designed one-dimensional grating waveguide structure device, which corresponds to the content of step S2 in the method. When preparing the one-dimensional grating waveguide structure device, the non-absorbing medium material of the substrate adopts a silicon dioxide substrate; the preparation process adopts a standard ultra-clean room semiconductor micro-nano processing process.

[0038] The semiconductor micro-nano processing technology in the clean room is a highly precise technology used to manufacture micron or even nanometer-level electronic components, such as integrated circuits, sensors, actuators, and micro-electromechanical systems. These processes are carried out in an ultra-clean environment to ensure that the products are free from contamination, thereby achieving the required performance and reliability. The one-dimensional grating waveguide structure device of this embodiment is also particularly suitable for preparation under this process.

[0039] In this embodiment, Figure 7 As shown, the preparation process of a one-dimensional grating waveguide structure device includes the following steps: S21, preparing a dielectric layer on a silicon dioxide substrate by electron beam sputtering; S22, mixing the basic components of the flexible material PMDS and the curing agent in a ratio of 10:1 to obtain a PMDS prepolymer; uniformly dropping the PMDS prepolymer on the dielectric layer, and evenly spin coating it using a coating machine, and then heating and curing it on a constant temperature table at a temperature of 80° C. to obtain a PDMS thin film layer; S23, using an electron beam lithography method to perform a pattern mask on the PDMS thin film layer, and then using plasma etching, electron beam sputtering and metal stripping methods in sequence to obtain a PDMS grating pattern with a one-dimensional grating structure as a grating layer; S24. Using a slicing method, a one-dimensional grating waveguide structure device is obtained to complete the preparation process.

[0040] Example 3 Based on any of the above embodiments, this embodiment introduces the content of step S3 in the method in detail. When performing pressure calibration, the incident light is irradiated on the one-dimensional grating waveguide structure device, and the projection direction of the incident light on the horizontal plane is the same as the grating period length direction of the grating layer with a one-dimensional grating structure in the one-dimensional grating waveguide structure device; the pressure value is smoothly applied to the one-dimensional grating waveguide structure device, and the movement parameters of the reflection spectrum of the incident light after passing through the one-dimensional grating waveguide structure device at different pressure values ​​are recorded respectively as calibration results of different pressure values.

[0041] like Figure 8 As shown, the experimental pressure measurement system of the high-speed flow field includes a spectrometer, a reflector, an airflow space and a detector; when measuring the flow field pressure, the aircraft model is placed in the airflow space, and the calibrated one-dimensional grating waveguide structure device is fixed on the surface of the aircraft model; the spectrometer is used to emit incident light with preset parameters, and the horizontal plane projection direction and the incident angle of the incident light are adjusted through the reflector so that the incident light illuminates the one-dimensional grating waveguide structure device; the detector is used to record the reflection spectrum generated by the incident light after passing through the one-dimensional grating waveguide structure device, and compared with the calibration result, the flow field surface pressure of the aircraft model in the current airflow space is obtained, and the flow field pressure measurement is completed.

[0042] In summary, the method of the present invention can closely fit the model surface for non-invasive measurement without interfering with the flow field characteristics. It also has the advantages of anti-interference, strong stability and low maintenance cost, providing strong technical support for the flow field research of future high-speed aircraft.

Claims

1. A method for measuring flow field surface pressure based on reflection spectroscopy, characterized in that: The method comprises the following steps: S1. Design one-dimensional grating waveguide structure device based on grating anomaly phenomenon in grating theory; S2. Prepare the designed one-dimensional grating waveguide structure device; S3. Perform pressure calibration on the prepared one-dimensional grating waveguide structure device, and after calibration, place it in the experimental pressure measurement system of the high-speed flow field; measure the flow field pressure on the model surface through the reflection spectrum of the one-dimensional grating waveguide structure device.

2. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 1, characterized in that: In step S1, the designed one-dimensional grating waveguide structure device includes three layers of grating waveguide structure, which are a grating layer, a dielectric layer and a substrate from top to bottom; for the grating layer, it is designed as a one-dimensional grating structure arranged along the length direction of the one-dimensional grating waveguide structure device.

3. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 2, characterized in that: The material of the grating layer is the flexible material PMDS, and the materials of the dielectric layer and the substrate are both non-absorption dielectric materials; when the structural parameters of the grating layer made of the flexible material PMDS change, the resonance wavelength changes, resulting in a resonance anomaly phenomenon, which redistributes the light field energy and further changes the reflection spectrum of the one-dimensional grating waveguide structure device.

4. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 2, characterized in that: The design process of one-dimensional grating waveguide structure device is as follows: Determine the material refractive index of the grating layer , the material refractive index of the dielectric layer and the refractive index of the substrate material ; For a grating layer with a one-dimensional grating structure, determine the grating period , Fill Factor , and the central wavelength of the incident light required for the grating layer to work is recorded as , the incident angle is recorded as , so that the projection direction of the incident light on the horizontal plane is the same as the grating period length direction of the one-dimensional grating structure; Determine the thickness of the grating layer and the thickness of the dielectric layer , and set constraints on the refractive index: the material refractive index of the dielectric layer At the same time, it is greater than the refractive index of the material of the grating layer and the refractive index of the substrate material ; Then, based on the slab waveguide theory, the characteristic equations of the one-dimensional grating waveguide structure device in TE and TM modes are obtained: In the two characteristic equations, the three intermediate parameters , , ;in is the diffraction order, is the incident light wave vector, is the propagation constant; when the first Propagation constant of the evanescent wave and the dielectric layer The propagation constant of the waveguide mode When matching, The evanescent wave resonates with the guided mode in the dielectric layer, so that the energy of the incident light is effectively coupled to the waveguide mode, thereby obtaining the following formula: In the formula, ; Thus, the design of one-dimensional grating waveguide structure devices is realized.

5. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 4, characterized in that: Based on the design process of one-dimensional grating waveguide structure device, the thin film anti-reflection layer design principle is adopted to design the grating layer and the dielectric layer into a thin film structure, and the optical thickness of the grating layer and the dielectric layer is selected to be the central wavelength of the incident light. ,Right now , is the equivalent refractive index of the grating layer.

6. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 5, characterized in that: The specific design parameters of the three-layer grating waveguide structure of the one-dimensional grating waveguide structure device are: the central wavelength of the incident light , and TE polarization is used; the refractive index of the material of the grating layer ,thickness ; Material refractive index of the dielectric layer ,thickness ; Refractive index of the substrate material ; Grating period of the grating layer , filling factor .

7. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 3, characterized in that: In step S2, when preparing a one-dimensional grating waveguide structure device, the non-absorbing medium material of the base is a silicon dioxide substrate; and the preparation process adopts a standard clean room semiconductor micro-nano processing process.

8. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 7, characterized in that: The preparation process of a one-dimensional grating waveguide structure device includes the following steps: S21, preparing a dielectric layer on a silicon dioxide substrate by electron beam sputtering; S22, mixing the basic components of the flexible material PMDS and the curing agent in a ratio of 10:1 to obtain a PMDS prepolymer; uniformly dropping the PMDS prepolymer on the dielectric layer, and evenly spin coating it using a coating machine, and then heating and curing it on a constant temperature table at a temperature of 80° C. to obtain a PDMS thin film layer; S23, using an electron beam lithography method to perform a pattern mask on the PDMS thin film layer, and then using plasma etching, electron beam sputtering and metal stripping methods in sequence to obtain a PDMS grating pattern with a one-dimensional grating structure as a grating layer; S24. Using a slicing method, a one-dimensional grating waveguide structure device is obtained to complete the preparation process.

9. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 1, characterized in that: In step S3, when performing pressure calibration, the incident light is made to illuminate the one-dimensional grating waveguide structure device, so that the projection direction of the incident light on the horizontal plane is the same as the grating period length direction of the grating layer with a one-dimensional grating structure in the one-dimensional grating waveguide structure device; the pressure value is smoothly applied to the one-dimensional grating waveguide structure device, and the movement parameters of the reflection spectrum of the incident light after passing through the one-dimensional grating waveguide structure device at different pressure values ​​are recorded respectively as the calibration results of different pressure values.

10. The method for measuring flow field surface pressure based on reflection spectroscopy according to claim 9, characterized in that: The experimental pressure measurement system of the high-speed flow field includes a spectrometer, a reflector, an airflow space and a detector. When measuring the flow field pressure, the aircraft model is placed in the airflow space, and the calibrated one-dimensional grating waveguide structure device is fixed on the surface of the aircraft model. The spectrometer is used to emit incident light with preset parameters, and the horizontal plane projection direction and the incident angle of the incident light are adjusted through the reflector so that the incident light illuminates the one-dimensional grating waveguide structure device. The detector is used to record the reflection spectrum generated by the incident light after passing through the one-dimensional grating waveguide structure device, and compared with the calibration result, the surface pressure of the flow field of the aircraft model in the current airflow space is obtained, and the flow field pressure measurement is completed.

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