System and method for measuring surface pressure of wind tunnel model based on double-layer PSP

Abstract

The invention discloses a wind tunnel model surface pressure measuring system and method based on a double-layer PSP, and belongs to the technical field of aerodynamic wind tunnel test detection. The microsecond pulsating pressure field and the microsecond pulsating temperature field can be measured at the same time on the premise that microsecond pressure response time is kept. A double-layer PSP coating is sprayed on the surface of a test model, mark points are arranged on the double-layer PSP coating, a first lens and a first optical filter are sequentially installed on a first high-speed camera, and a second lens and a second optical filter are sequentially installed on a second high-speed camera; the first high-speed camera and the second high-speed camera are respectively connected with a synchronizer, and the synchronizer is connected with a computer; laser emitted by the excitation light source is irradiated on the double-layer PSP coating to obtain fluorescence for exciting the double-layer PSP coating. According to the invention, the correction of microsecond pulsating pressure errors caused by non-uniform temperature in the process of measuring the surface pressure of the wind tunnel model is realized.

Description

Technical Field

[0001] This invention belongs to the field of aerodynamic wind tunnel testing technology, specifically relating to a wind tunnel model surface pressure measurement system and method based on a double-layer PSP. Background Technology

[0002] Pressure Sensitive Paint (PSP) technology is a non-contact optical surface pressure measurement technique used for measuring pressure on model surfaces in wind tunnel tests. The principle of PSP is that pressure-sensitive probe molecules with an oxygen quenching effect emit fluorescence under excitation light of a specific wavelength. The fluorescence intensity is inversely proportional to the oxygen content (air pressure) surrounding the pressure-sensitive probe molecules. Compared to traditional contact surface pressure measurement techniques that involve opening pressure measurement holes on the model surface, PSP technology offers advantages such as non-contact operation, high spatial resolution, ease of fabrication, and low cost. The light intensity method is a typical PSP testing technique, calculating the pressure field based on the ratio of windy test images to windless reference images and the quantitative relationship between pressure and temperature. Because pressure-sensitive probe molecules have a thermal quenching effect—meaning the probe's fluorescence intensity is also inversely proportional to its temperature—measurement errors due to uneven model temperature occur in actual pressure measurements, known as the temperature effect. Two-component PSP effectively suppresses temperature-induced pressure errors. It contains both a pressure-sensitive probe and a reference probe, both fluorescent components. The reference probe is insensitive to pressure, only to temperature. Therefore, in the intensity-based method of pressure measurement, temperature correction can be achieved by using the ratio of the fluorescence images of the two probes. Currently, existing two-component PSPs can effectively suppress steady-state and millisecond-level pressure errors. However, the response time cannot reach below 1 ms or even below 100 μs, making it impossible to achieve pulsating pressure measurements above 1000 Hz. Summary of the Invention

[0003] The problem to be solved by this invention is to achieve simultaneous measurement of microsecond-level pulsating pressure field and temperature field while maintaining microsecond-level pressure response time. A wind tunnel model surface pressure measurement system and measurement method based on a double-layer PSP are proposed.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A wind tunnel model surface pressure measurement system based on a double-layer PSP includes a double-layer PSP coating, marker points, a first high-speed camera, a second high-speed camera, a first lens, a second lens, a first filter, a second filter, an excitation light source, a synchronizer, and a computer.

[0006] The double-layer PSP coating is sprayed onto the surface of the test model, and marking points are set on the double-layer PSP coating. A first lens and a first filter are sequentially installed on the first high-speed camera, and a second lens and a second filter are sequentially installed on the second high-speed camera. The first high-speed camera and the second high-speed camera are respectively connected to a synchronizer, and the synchronizer is connected to a computer.

[0007] The laser emitted by the excitation source irradiates the double-layer PSP coating, thereby exciting the fluorescence of the double-layer PSP coating.

[0008] Furthermore, the dual-layer PSP coating includes a primer layer, a reference layer, and a pressure-sensitive layer. An air spray gun is used to uniformly spray the coating onto the surface of the test model in the order of spraying the primer layer, the reference layer, and the pressure-sensitive layer.

[0009] The primer layer is a white shielding primer;

[0010] The pressure-sensitive layer is composed of a pressure-sensitive probe and a first solvent. The pressure-sensitive probe is PtTFPP and the first solvent is trifluorotoluene. The mass-volume ratio of the pressure-sensitive probe to the first solvent is 50mg:100ml.

[0011] The reference layer consists of a reference probe, an adhesive, and a second solvent. The reference probe is (BaSr)₂SiO₄:Eu 2+ The binder is acrylic emulsion, the second solvent is deionized water, and the mass-volume ratio of the reference probe, binder and second solvent is 40g:3g:100ml.

[0012] Furthermore, the thickness of the reference layer is 20–30 μm, and the pressure-sensitive layer is adsorbed onto the porous structure of the reference layer.

[0013] Furthermore, the first filter is a bandpass filter with a center wavelength of 535nm and a bandwidth of 30nm, and the second filter is a bandpass filter with a center wavelength of 650nm and a bandwidth of 10nm.

[0014] Furthermore, the number of excitation light sources is 3-5, and the center wavelength of the laser light from the excitation light sources is 405nm.

[0015] A method for measuring surface pressure of a wind tunnel model based on a dual-layer PSP, implemented using the aforementioned dual-layer PSP-based wind tunnel model surface pressure measurement system, includes the following steps:

[0016] S1. Applying a double-layer PSP coating: First, clean the surface of the test model with a lint-free cloth dampened with anhydrous ethanol. Then, apply the primer layer using an air spray gun. After the primer layer is applied, place the test model in a constant temperature oven and heat it at 70°C for 6 hours, followed by natural cooling. Apply the reference layer using an air spray gun. After the reference layer dries naturally, apply the pressure-sensitive layer using an air spray gun. After the pressure-sensitive layer dries naturally, the PSP coating is obtained.

[0017] S2. Marker point arrangement: Measure the surface of the test model with a flexible ruler, select several spanwise sections, select several chord length positions on each spanwise section, and draw circular marker points using a black marker or stamp;

[0018] S3. Set up the PSP test system: Install the test model in the wind tunnel test section, arrange multiple excitation light sources to make the surface of the test model uniformly illuminated; set up the first high-speed camera and the second high-speed camera to capture images of the reference layer and the pressure-sensitive layer respectively; adjust the first high-speed camera and the second high-speed camera to capture the field of view of the entire test model, and connect them to the synchronizer and the computer;

[0019] S4. Camera Calibration: Use a calibration board to calibrate the first high-speed camera and the second high-speed camera, and obtain the camera calibration coefficients;

[0020] S5. Experimental Image Acquisition: The wind tunnel starts blowing air, the excitation light source is turned on, and after the flow field stabilizes, the computer controls the synchronizer, which controls the first high-speed camera and the second high-speed camera to start synchronously acquiring images of the reference layer and pressure-sensitive layer of the PSP experiment. After the acquisition is completed, the computer controls the camera to stop recording and store the data.

[0021] S6. Reference Image Acquisition: In windless conditions, turn on the excitation light source, and the computer controls the synchronizer. The synchronizer controls the first high-speed camera and the second high-speed camera to start synchronously acquiring images of the reference layer and pressure-sensitive layer of the PSP test. After the acquisition is completed, the computer controls the camera to stop recording and store the data.

[0022] S7. Dark Image Acquisition: Turn off the excitation source to ensure there is no stray light interference in the wind tunnel. The computer controls the first high-speed camera and the second high-speed camera to capture dark images and store the data. The dark images include the effects of camera dark current noise.

[0023] S8. The images and dark images of the reference layer and pressure-sensitive layer acquired in steps S5-S8 are processed to obtain the surface pressure test results of the wind tunnel model based on the double-layer PSP.

[0024] Furthermore, the specific implementation method of step S8 includes the following steps:

[0025] S8.1. Image distortion correction: For all images of the pressure-sensitive layer and the reference layer captured, image distortion correction is performed according to the camera calibration coefficient to obtain the image of the pressure-sensitive layer and the image of the reference layer after distortion correction;

[0026] S8.2. Image Averaging: The reference image and dark image of the pressure-sensitive layer and reference layer after distortion correction obtained in step S8.1 are averaged to obtain the light intensity of the average reference image of the pressure-sensitive layer. Light intensity of average dark image Light intensity of the average reference image of the reference layer Light intensity of average dark image ;

[0027] S8.3. Marker point identification: For all test images of the distortion-corrected pressure-sensitive layer and reference layer obtained in step S8.1 and the average reference image obtained in step S8.2, mark points are identified by detecting circular contours based on Hough transform, or the first set of mark points is manually selected and the mark points of all test images and reference images are obtained by normalized two-dimensional cross-correlation.

[0028] S8.4. Image Registration: For all test images and average reference images of the pressure-sensitive layer and the reference layer, perform image registration according to the marker points identified in step S8.3, and align all test images of the pressure-sensitive layer and the reference layer to the coordinates of the average reference image respectively;

[0029] S8.5. Calculate the light intensity ratio: For the test images, average reference images, and average dark images of the pressure-sensitive layer and the reference layer, calculate the light intensity ratio of the pressure-sensitive layer and the light intensity ratio of the reference layer;

[0030] S8.6. Mask Calculation: Based on the light intensity ratio of the pressure-sensitive layer and the light intensity ratio of the reference layer, perform mask calculation, remove invalid pixels on the image, generate a mask based on the gray-scale thresholding method of the reference image, or manually select a mask to obtain the light intensity ratio of the pressure-sensitive layer and the reference layer after masking;

[0031] S8.7. Light intensity ratio filtering: The light intensity ratio between the pressure-sensitive layer and the reference layer after masking is filtered and filled to obtain the light intensity ratio between the pressure-sensitive layer and the reference layer after filtering and filling.

[0032] S8.8. Temperature field calculation: For the filtered reference layer light intensity ratio, the light intensity ratio is converted into a temperature field according to the prior calibration relationship between the light intensity ratio and temperature;

[0033] S8.9. Pressure field and temperature field matching: Based on the marker points identified in step S8.3, the light intensity ratio of the pressure-sensitive layer after filtering and filling is aligned with the coordinates of the temperature field at each moment.

[0034] S8.10. Pressure Field Temperature Correction: For the coordinate transformation of the pressure-sensitive layer in the i-th frame, the light intensity ratio is adjusted based on the temperature value of its effective pixel j. The ratio of light intensity to pressure-sensitive channel The prior calibration relationship between the light intensity ratio and pressure and temperature obtained in the laboratory is used to convert the light intensity ratio of the pressure-sensitive layer into a pressure value. ;

[0035] S8.11. Repeat step S8.10 until all valid pixels have been calculated, completing the temperature correction calculation for each image in the time series and obtaining the corrected pressure field.

[0036] Furthermore, in step S8.5, for the i-th frame of the test image of the pressure-sensitive layer... Light intensity ratio for:

[0037] ;

[0038] For the i-th frame of the reference layer test image Light intensity ratio for:

[0039] .

[0040] Furthermore, the prior calibration relationship of the temperature field in step S8.8 is expressed as:

[0041]

[0042] in, Let be the temperature corresponding to the i-th frame of the image. For reference temperature, , These are the first, second, and third coefficients of the prior calibration relation for the temperature field, respectively.

[0043] Furthermore, the prior calibration relation of the pressure field in step S8.10 is expressed as:

[0044]

[0045] in, For reference pressure, , These are the first, second, and third coefficients of the prior calibration relation for the pressure field, respectively.

[0046] The beneficial effects of this invention are:

[0047] This invention discloses a wind tunnel model surface pressure measurement system based on a dual-layer PSP, which can simultaneously measure microsecond-level pulsating pressure and temperature fields while maintaining a microsecond-level pressure response time, thus creating conditions for temperature correction of the microsecond-level pulsating pressure field. This invention forms a porous coating using nanoscale reference probe particles, improving oxygen diffusivity to increase the coating's response speed to the microsecond level while providing temperature reference capability. This invention achieves simultaneous measurement of the microsecond-level pulsating pressure and temperature fields by synchronously acquiring the fluorescence of the pressure-sensitive probe and reference probe using dual cameras and comparing the results. This invention employs a pressure-temperature field coupling calculation method combined with prior calibration data to correct for microsecond-level pulsating pressure errors caused by temperature inhomogeneity. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the surface pressure measurement system for a wind tunnel model based on a double-layer PSP, as described in this invention.

[0049] Figure 2 This is a flowchart of a wind tunnel model surface pressure measurement method based on a double-layer PSP as described in this invention;

[0050] Figure 3 This is a graph showing the PSP response time measured by a wind tunnel model surface pressure measurement system based on a double-layer PSP, as described in this invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0052] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0053] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 -Appendix Figure 3 Detailed explanation is as follows:

[0054] Example 1:

[0055] A wind tunnel model surface pressure measurement system based on a double-layer PSP includes a double-layer PSP coating 1, marker points 2, a first high-speed camera 3, a second high-speed camera 4, a first lens 5, a second lens 6, a first filter 7, a second filter 8, an excitation light source 9, a synchronizer 10, and a computer 11.

[0056] The double-layer PSP coating 1 is sprayed on the surface of the test model 12. Marking points 2 are provided on the double-layer PSP coating 1. The first high-speed camera 3 is equipped with a first lens 5 and a first filter 7 in sequence. The second high-speed camera 4 is equipped with a second lens 6 and a second filter 8 in sequence. The first high-speed camera 3 and the second high-speed camera 4 are respectively connected to a synchronizer 10. The synchronizer 10 is connected to a computer 11.

[0057] The laser emitted by the excitation light source 9 irradiates the double-layer PSP coating 1, thereby exciting the fluorescence of the double-layer PSP coating 1.

[0058] Furthermore, the double-layer PSP coating 1 includes a primer layer, a reference layer, and a pressure-sensitive layer. It is uniformly sprayed on the surface of the test model 12 using an air spray gun in the order of spraying the primer layer, the reference layer, and the pressure-sensitive layer.

[0059] The primer layer is a white shielding primer;

[0060] The pressure-sensitive layer is composed of a pressure-sensitive probe and a first solvent. The pressure-sensitive probe is PtTFPP and the first solvent is trifluorotoluene. The mass-volume ratio of the pressure-sensitive probe to the first solvent is 50mg:100ml.

[0061] The reference layer consists of a reference probe, an adhesive, and a second solvent. The reference probe is (BaSr)₂SiO₄:Eu 2+ The binder is acrylic emulsion, the second solvent is deionized water, and the mass-volume ratio of the reference probe, binder and second solvent is 40g:3g:100ml.

[0062] Furthermore, the thickness of the reference layer is 20–30 μm, and the pressure-sensitive layer is adsorbed onto the porous structure of the reference layer.

[0063] Furthermore, the first filter 7 is a bandpass filter with a center wavelength of 535nm and a bandwidth of 30nm, and the second filter 8 is a bandpass filter with a center wavelength of 650nm and a bandwidth of 10nm.

[0064] Furthermore, the number of excitation light sources 9 is 3-5, and the center wavelength of the laser light from the excitation light sources 9 is 405nm.

[0065] Example 2:

[0066] A method for measuring surface pressure of a wind tunnel model based on a dual-layer PSP, implemented using the wind tunnel model surface pressure measurement system based on a dual-layer PSP described in Example 1, includes the following steps:

[0067] S1. Applying a double-layer PSP coating: First, clean the surface of the test model with a lint-free cloth dampened with anhydrous ethanol. Then, apply the primer layer using an air spray gun. After the primer layer is applied, place the test model in a constant temperature oven and heat it at 70°C for 6 hours, followed by natural cooling. Apply the reference layer using an air spray gun. After the reference layer dries naturally, apply the pressure-sensitive layer using an air spray gun. After the pressure-sensitive layer dries naturally, the PSP coating is obtained.

[0068] S2. Marker point arrangement: Measure the surface of the test model with a flexible ruler, select several spanwise sections, select several chord length positions on each spanwise section, and draw circular marker points using a black marker or stamp;

[0069] S3. Set up the PSP test system: Install the test model in the wind tunnel test section, arrange multiple excitation light sources to make the surface of the test model uniformly illuminated; set up the first high-speed camera and the second high-speed camera to capture images of the reference layer and the pressure-sensitive layer respectively; adjust the first high-speed camera and the second high-speed camera to capture the field of view of the entire test model, and connect them to the synchronizer and the computer;

[0070] S4. Camera Calibration: Use a calibration board to calibrate the first high-speed camera and the second high-speed camera, and obtain the camera calibration coefficients;

[0071] S5. Experimental Image Acquisition: The wind tunnel starts blowing air, the excitation light source is turned on, and after the flow field stabilizes, the computer controls the synchronizer, which controls the first high-speed camera and the second high-speed camera to start synchronously acquiring images of the reference layer and pressure-sensitive layer of the PSP experiment. After the acquisition is completed, the computer controls the camera to stop recording and store the data.

[0072] S6. Reference Image Acquisition: In windless conditions, turn on the excitation light source, and the computer controls the synchronizer. The synchronizer controls the first high-speed camera and the second high-speed camera to start synchronously acquiring images of the reference layer and pressure-sensitive layer of the PSP test. After the acquisition is completed, the computer controls the camera to stop recording and store the data.

[0073] S7. Dark Image Acquisition: Turn off the excitation source to ensure there is no stray light interference in the wind tunnel. The computer controls the first high-speed camera and the second high-speed camera to capture dark images and store the data. The dark images include the effects of camera dark current noise.

[0074] S8. The images and dark images of the reference layer and pressure-sensitive layer acquired in steps S5-S8 are processed to obtain the surface pressure test results of the wind tunnel model based on the double-layer PSP.

[0075] Furthermore, the specific implementation method of step S8 includes the following steps:

[0076] S8.1. Image distortion correction: For all images of the pressure-sensitive layer and the reference layer captured, image distortion correction is performed according to the camera calibration coefficient to obtain the image of the pressure-sensitive layer and the image of the reference layer after distortion correction;

[0077] S8.2. Image Averaging: The reference image and dark image of the pressure-sensitive layer and reference layer after distortion correction obtained in step S8.1 are averaged to obtain the light intensity of the average reference image of the pressure-sensitive layer. Light intensity of average dark image Light intensity of the average reference image of the reference layer Light intensity of average dark image ;

[0078] S8.3. Marker point identification: For all test images of the distortion-corrected pressure-sensitive layer and reference layer obtained in step S8.1 and the average reference image obtained in step S8.2, mark points are identified by detecting circular contours based on Hough transform, or the first set of mark points is manually selected and the mark points of all test images and reference images are obtained by normalized two-dimensional cross-correlation.

[0079] S8.4. Image Registration: For all test images and average reference images of the pressure-sensitive layer and the reference layer, perform image registration according to the marker points identified in step S8.3, and align all test images of the pressure-sensitive layer and the reference layer to the coordinates of the average reference image respectively;

[0080] Furthermore, the preferred image registration method is the direct linear transformation method, but the projection coordinate transformation method or the cubic surface coordinate transformation method can also be used;

[0081] S8.5. Calculate the light intensity ratio: For the test images, average reference images, and average dark images of the pressure-sensitive layer and the reference layer, calculate the light intensity ratio of the pressure-sensitive layer and the light intensity ratio of the reference layer;

[0082] Furthermore, in step S8.5, for the i-th frame of the test image of the pressure-sensitive layer... Light intensity ratio for:

[0083] ;

[0084] For the i-th frame of the reference layer test image Light intensity ratio for:

[0085] .

[0086] S8.6. Mask Calculation: Based on the light intensity ratio of the pressure-sensitive layer and the light intensity ratio of the reference layer, perform mask calculation, remove invalid pixels on the image, generate a mask based on the gray-scale thresholding method of the reference image, or manually select a mask to obtain the light intensity ratio of the pressure-sensitive layer and the reference layer after masking;

[0087] S8.7. Light intensity ratio filtering: The light intensity ratio between the pressure-sensitive layer and the reference layer after masking is filtered and filled to obtain the light intensity ratio between the pressure-sensitive layer and the reference layer after filtering and filling.

[0088] S8.8. Temperature field calculation: For the filtered reference layer light intensity ratio, the light intensity ratio is converted into a temperature field according to the prior calibration relationship between the light intensity ratio and temperature;

[0089] Furthermore, the prior calibration relationship of the temperature field in step S8.8 is expressed as:

[0090]

[0091] in, Let be the temperature corresponding to the i-th frame of the image. For reference temperature, , These are the first, second, and third coefficients of the prior calibration relation for the temperature field, respectively.

[0092] S8.9. Pressure field and temperature field matching: Based on the marker points identified in step S8.3, the light intensity ratio of the pressure-sensitive layer after filtering and filling is aligned with the coordinates of the temperature field at each moment.

[0093] Furthermore, the preferred alignment method is the direct linear transformation method, but the projected coordinate transformation method or the cubic surface coordinate transformation method can also be used;

[0094] S8.10. Pressure Field Temperature Correction: For the coordinate transformation of the pressure-sensitive layer in the i-th frame, the light intensity ratio is adjusted based on the temperature value of its effective pixel j. The ratio of light intensity to pressure-sensitive channel The prior calibration relationship between the light intensity ratio and pressure and temperature obtained in the laboratory is used to convert the light intensity ratio of the pressure-sensitive layer into a pressure value. ;

[0095] Furthermore, the prior calibration relation of the pressure field in step S8.10 is expressed as:

[0096]

[0097] in, For reference pressure, , These are the first, second, and third coefficients of the prior calibration relation for the pressure field, respectively.

[0098] S8.11. Repeat step S8.10 until all valid pixels have been calculated, completing the temperature correction calculation for each image in the time series and obtaining the corrected pressure field.

[0099] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0100] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A wind tunnel model surface pressure measurement system based on a double-layer PSP, characterized in that, Includes a double-layer PSP coating (1), markers (2), a first high-speed camera (3), a second high-speed camera (4), a first lens (5), a second lens (6), a first filter (7), a second filter (8), an excitation light source (9), a synchronizer (10), and a computer (11). The double-layer PSP coating (1) is sprayed on the surface of the test model (12). Marking points (2) are set on the double-layer PSP coating (1). The first high-speed camera (3) is equipped with a first lens (5) and a first filter (7) in sequence. The second high-speed camera (4) is equipped with a second lens (6) and a second filter (8) in sequence. The first high-speed camera (3) and the second high-speed camera (4) are respectively connected to a synchronizer (10). The synchronizer (10) is connected to a computer (11). The laser emitted by the excitation light source (9) irradiates the double-layer PSP coating (1), thereby exciting the fluorescence of the double-layer PSP coating (1).

2. The wind tunnel model surface pressure measurement system based on a double-layer PSP according to claim 1, characterized in that, The double-layer PSP coating (1) includes a primer layer, a reference layer and a pressure-sensitive layer. The coating is uniformly sprayed on the surface of the test model (12) using an air spray gun in the order of spraying the primer layer, the reference layer and the pressure-sensitive layer. The primer layer is a white shielding primer; The pressure-sensitive layer is composed of a pressure-sensitive probe and a first solvent. The pressure-sensitive probe is PtTFPP and the first solvent is trifluorotoluene. The mass-volume ratio of the pressure-sensitive probe to the first solvent is 50mg:100ml. The reference layer consists of a reference probe, an adhesive, and a second solvent. The reference probe is (BaSr)₂SiO₄:Eu 2+ The binder is acrylic emulsion, the second solvent is deionized water, and the mass-volume ratio of the reference probe, binder and second solvent is 40g:3g:100ml.

3. The wind tunnel model surface pressure measurement system based on a double-layer PSP according to claim 2, characterized in that, The thickness of the reference layer is 20-30 μm, and the pressure-sensitive layer is adsorbed onto the porous structure of the reference layer.

4. The wind tunnel model surface pressure measurement system based on a double-layer PSP according to claim 3, characterized in that, The first filter (7) is a bandpass filter with a center wavelength of 535nm and a bandwidth of 30nm, and the second filter (8) is a bandpass filter with a center wavelength of 650nm and a bandwidth of 10nm.

5. The wind tunnel model surface pressure measurement system based on a double-layer PSP according to claim 4, characterized in that, The number of excitation light sources (9) is 3-5, and the center wavelength of the laser of the excitation light source (9) is 405nm.

6. A method for measuring surface pressure of a wind tunnel model based on a double-layer PSP, implemented using the wind tunnel model surface pressure measurement system based on a double-layer PSP as described in claims 1-5, characterized in that... Includes the following steps: S1. Applying a double-layer PSP coating: First, clean the surface of the test model with a lint-free cloth dampened with anhydrous ethanol. Then, apply the primer layer using an air spray gun. After the primer layer is applied, place the test model in a constant temperature oven and heat it at 70°C for 6 hours, followed by natural cooling. Apply the reference layer using an air spray gun. After the reference layer dries naturally, apply the pressure-sensitive layer using an air spray gun. After the pressure-sensitive layer dries naturally, the PSP coating is obtained. S2. Marker point arrangement: Measure the surface of the test model with a flexible ruler, select several spanwise sections, select several chord length positions on each spanwise section, and draw circular marker points using a black marker or stamp; S3. Set up the PSP test system: Install the test model in the wind tunnel test section and arrange multiple excitation light sources to make the surface of the test model uniformly illuminated; Set up a first high-speed camera and a second high-speed camera to capture images of the reference layer and the pressure-sensitive layer, respectively; adjust the first high-speed camera and the second high-speed camera to capture the entire field of view of the experimental model, and connect them to a synchronizer and a computer; S4. Camera Calibration: Use a calibration board to calibrate the first high-speed camera and the second high-speed camera, and obtain the camera calibration coefficients; S5. Experimental Image Acquisition: The wind tunnel starts blowing air, the excitation light source is turned on, and after the flow field stabilizes, the computer controls the synchronizer, which controls the first high-speed camera and the second high-speed camera to start synchronously acquiring images of the reference layer and pressure-sensitive layer of the PSP experiment. After the acquisition is completed, the computer controls the camera to stop recording and store the data. S6. Reference Image Acquisition: In windless conditions, turn on the excitation light source, and the computer controls the synchronizer. The synchronizer controls the first high-speed camera and the second high-speed camera to start synchronously acquiring images of the reference layer and pressure-sensitive layer of the PSP test. After the acquisition is completed, the computer controls the camera to stop recording and store the data. S7. Dark Image Acquisition: Turn off the excitation source to ensure there is no stray light interference in the wind tunnel. The computer controls the first high-speed camera and the second high-speed camera to capture dark images and store the data. The dark images include the effects of camera dark current noise. S8. The images and dark images of the reference layer and pressure-sensitive layer acquired in steps S5-S8 are processed to obtain the surface pressure test results of the wind tunnel model based on the double-layer PSP.

7. The method for measuring surface pressure of a wind tunnel model based on a double-layer PSP according to claim 6, characterized in that, The specific implementation method of step S8 includes the following steps: S8.

1. Image distortion correction: For all images of the pressure-sensitive layer and the reference layer captured, image distortion correction is performed according to the camera calibration coefficient to obtain the image of the pressure-sensitive layer and the image of the reference layer after distortion correction; S8.

2. Image Averaging: The reference image and dark image of the pressure-sensitive layer and reference layer after distortion correction obtained in step S8.1 are averaged to obtain the light intensity of the average reference image of the pressure-sensitive layer. Light intensity of average dark image Light intensity of the average reference image of the reference layer Light intensity of average dark image ; S8.

3. Marker point identification: For all test images of the distortion-corrected pressure-sensitive layer and reference layer obtained in step S8.1 and the average reference image obtained in step S8.2, mark points are identified by detecting circular contours based on Hough transform, or the first set of mark points is manually selected and the mark points of all test images and reference images are obtained by normalized two-dimensional cross-correlation. S8.

4. Image Registration: For all test images and average reference images of the pressure-sensitive layer and the reference layer, perform image registration according to the marker points identified in step S8.3, and align all test images of the pressure-sensitive layer and the reference layer to the coordinates of the average reference image respectively; S8.

5. Calculate the light intensity ratio: For the test images, average reference images, and average dark images of the pressure-sensitive layer and the reference layer, calculate the light intensity ratio of the pressure-sensitive layer and the light intensity ratio of the reference layer; S8.

6. Mask Calculation: Based on the light intensity ratio of the pressure-sensitive layer and the light intensity ratio of the reference layer, perform mask calculation, remove invalid pixels on the image, generate a mask based on the gray-scale thresholding method of the reference image, or manually select a mask to obtain the light intensity ratio of the pressure-sensitive layer and the reference layer after masking; S8.

7. Light intensity ratio filtering: The light intensity ratio between the pressure-sensitive layer and the reference layer after masking is filtered and filled to obtain the light intensity ratio between the pressure-sensitive layer and the reference layer after filtering and filling. S8.

8. Temperature field calculation: For the filtered reference layer light intensity ratio, the light intensity ratio is converted into a temperature field according to the prior calibration relationship between the light intensity ratio and temperature; S8.

9. Pressure field and temperature field matching: Based on the marker points identified in step S8.3, the light intensity ratio of the pressure-sensitive layer after filtering and filling is aligned with the coordinates of the temperature field at each moment. S8.

10. Pressure Field Temperature Correction: For the coordinate transformation of the pressure-sensitive layer in the i-th frame, the light intensity ratio is adjusted based on the temperature value of its effective pixel j. The ratio of light intensity to pressure-sensitive channel The prior calibration relationship between the light intensity ratio and pressure and temperature obtained in the laboratory is used to convert the light intensity ratio of the pressure-sensitive layer into a pressure value. ; S8.

11. Repeat step S8.10 until all valid pixels have been calculated, and complete the temperature correction calculation for each image in the time series to obtain the corrected pressure field.

8. The method for measuring surface pressure of a wind tunnel model based on a double-layer PSP according to claim 7, characterized in that, In step S8.5, for the i-th frame of the test image of the pressure-sensitive layer... Light intensity ratio for: ； For the i-th frame of the reference layer test image Light intensity ratio for: 。 9. The method for measuring surface pressure of a wind tunnel model based on a double-layer PSP according to claim 8, characterized in that, The prior calibration relation for the temperature field in step S8.8 is expressed as follows: ； in, Let i be the temperature corresponding to the i-th frame of the image. For reference temperature, , These are the first, second, and third coefficients of the prior calibration relation for the temperature field, respectively.

10. A method for measuring surface pressure of a wind tunnel model based on a double-layer PSP according to claim 9, characterized in that, The prior calibration relation for the pressure field in step S8.10 is expressed as follows: ； in, For reference pressure, , These are the first, second, and third coefficients of the prior calibration relation for the pressure field, respectively.

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