Device and method for synchronously measuring inner region and outer region of gas-solid two-phase boundary layer

Abstract

The invention discloses a gas-solid two-phase boundary layer inner and outer area synchronous measurement device, which comprises an experiment area for gas-solid two-phase flow to penetrate through, a high-energy pulse laser is arranged on the experiment area, fluorescent paint is sprayed on the inner wall of the experiment area, and a plurality of prime lens cameras are arranged on the periphery of the experiment area. The inner wall of the experimental area is provided with a telephoto lens and a double telephoto lens, and the telephoto lens camera and the prime lens camera are both connected with a synchronous controller; the invention also discloses a method for synchronously measuring the inner and outer regions of the gas-solid two-phase boundary layer. According to the invention, the measurement precision is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of boundary layer gas-solid two-phase velocity measurement, and particularly to a device and method for synchronously measuring the inner and outer regions of a gas-solid two-phase boundary layer. Background Art

[0002] Particle Image Velocimetry (PIV) technology is a non-contact measurement method that can obtain the planar and three-dimensional velocities of a flow field. Its basic principle is to uniformly seed tracer particles in the flow field, and then use a laser sheet light or volume light with uniform light intensity to illuminate the tracer particles in the flow. Then, a CCD / CMOS camera is used to capture the particle images through continuous double exposure or multiple exposures within a certain period of time. By performing cross-correlation operations on the windows at the same positions in the image pairs through the cross-correlation algorithm, the positions of the particles are obtained. The flow field velocity is calculated based on the time of the image pairs.

[0003] Based on the velocity measurement principle of PIV, it can be seen that the quality of the PIV velocity measurement results depends on the imaging quality of the tracer particles. PIV measurements generally use pulsed lasers as the illumination light source. This laser has the characteristics of strong energy and uniform intensity, but when it shines on the object surface, there will be strong reflection, which affects the recognition of tracer particles on the wall surface and has a significant impact on the velocity measurement of the object surface flow.

[0004] Some scholars have proposed adding baffles and restricting the incident laser path to avoid the reflection problem. For example, Patent 201910804073.9 designs a baffle device for PIV experiments to avoid reflection, and Patent 202110445421.5 conceives an anti-reflection device and its usage method for PIV experiments by restricting the incident laser path and customizing the shooting area, which effectively avoids some reflection problems. Patent 202111626952.0 uses the fluorescence PIV method to only excite the tracer particles to obtain longer wavelengths and filter out the surrounding ambient light and other stray light; then a filter is used to filter out other stray light to obtain a tracer particle image with higher contrast.

[0005] For the research on gas-solid two-phase measurement, the strong scattering of particles may mask the surrounding tracer particles, resulting in serious errors in the flow field measurement at that location, especially near the wall surface. The previous methods cannot well solve this problem.

[0006] In the existing gas-solid two-phase measurement, it is difficult to solve the wall surface reflection. The reflection near the measurement area of the wall surface is strong, and the signal-to-noise ratio of the obtained data tracer particles is low. In the existing gas-solid two-phase boundary layer flow, it is difficult to measure near the wall, especially in the viscous sublayer near the wall (y +The range of <5). At the same time, there is an interaction between different flow layers during the boundary layer flow, and this factor is not considered in the existing two-phase experimental measurements, and the synchronous measurement of the inner and outer regions. Summary of the Invention

[0007] To solve the problems existing in the prior art, the object of the present invention is to provide a device and method for synchronous measurement of the inner and outer regions of a gas-solid two-phase boundary layer, and the present invention improves the measurement accuracy.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a device for synchronous measurement of the inner and outer regions of a gas-solid two-phase boundary layer, including an experimental area for penetrating the gas-solid two-phase flow, a high-energy pulsed laser is provided on the experimental area, the inner wall of the experimental area is sprayed with a fluorescent coating, a plurality of fixed-focus lens cameras are provided outside the experimental area, a long-focus lens and a 2X teleconverter are provided on the inner wall of the experimental area, and both the long-focus lens camera and the fixed-focus lens camera are connected to a synchronous controller.

[0009] As a further improvement of the present invention, the high-energy pulsed laser is installed on the experimental area through an optical fiber.

[0010] The present invention also provides a method for synchronous measurement of the inner and outer regions of a gas-solid two-phase boundary layer, including the following steps:

[0011] Step 1: Calcinate and dye the glass bead particles;

[0012] Step 2: Install the device for synchronous measurement of the inner and outer regions of the gas-solid two-phase boundary layer as described above, and spray a fluorescent coating on the inner wall of the measurement device;

[0013] Step 3: Tracer particle seeding and laser calibration;

[0014] Step 4: Data acquisition and image processing.

[0015] As a further improvement of the present invention, in Step 1, the calcination of the glass bead particles is specifically as follows:

[0016] Preheating stage: Set the high-temperature furnace to a preset temperature and maintain a constant temperature for a preset time to ensure the stability of the temperature in the furnace;

[0017] Calcination: Uniformly spread the glass bead particles on a high-temperature-resistant ceramic crucible, and place the ceramic crucible in the furnace for calcination for a preset time;

[0018] Temperature increase control: During the calcination process, check the temperature curve every fixed time to ensure that the temperature fluctuation does not exceed the preset threshold;

[0019] Cooling: After the calcination is completed, slowly cool down to avoid cracks in the glass beads caused by sudden temperature drop. After cooling to room temperature, take out the glass beads for standby.

[0020] As a further improvement of the present invention, in step 1, the glass bead particles are dyed as follows:

[0021] Prepare the dyeing solution: According to the recommended use concentration of the dye, prepare a 5-10% Kiton 620 solution, add ethanol as a stabilizer to the solution, and the volume ratio of ethanol is 10-20% to improve the dispersibility of the dye in the solution and avoid precipitation; adjust the pH value of the solution to between 4 and 5, use a pH meter to monitor the acidity and alkalinity of the solution in real time, and fine-tune the acidity and alkalinity by adding NaOH or HCl;

[0022] Dyeing process: Add the calcined glass bead particles to the dyeing solution and mix them in a ratio of 1:10 by particle weight to solution volume; start the stirring device in the dyeing reactor, and control the stirring speed at 100-200 revolutions per minute; the dyeing reaction is carried out at room temperature, and the reaction time is 30 minutes to 1 hour to ensure that the dye is fully attached to the surface of the glass beads; during the dyeing process, take a small amount of samples every 10 minutes to observe the dyeing effect and check the uniformity and adhesion strength of the color on the particle surface;

[0023] Washing and drying: After dyeing is completed, stop stirring and take out the particles from the solution; wash the particles with deionized water multiple times, and assist with an ultrasonic cleaner each time to ensure that the dye is completely combined on the particle surface and remove the unbound dye; dry the washed particles in an oven at 50-60 degrees Celsius.

[0024] As a further improvement of the present invention, it also includes detecting the dyeing effect: Detect by a fluorescence microscope and observe the fluorescence emission effect of the glass bead particles under the illumination with an excitation wavelength of 620 nm.

[0025] As a further improvement of the present invention, in step 2, spraying the fluorescent coating on the inner wall of the measuring device is as follows:

[0026] Select the coating material: Mix the water-based fluorescent coating Kiton 620 with a polymer to prepare a uniform coating solution; conduct a stability test on the coating solution before the experiment starts to observe whether there is precipitation or caking to ensure the uniformity of the fluorescence intensity;

[0027] Spraying: Use spraying equipment to evenly spray the fluorescent coating on the wall surface of the experimental area of the experimental device, ensuring that the coating thickness is maintained between 10-50 microns; use a thickness gauge to check the uniformity of the coating and measure the thickness in different areas to ensure consistency; re-spray or adjust the uneven parts.

[0028] Fluorescence effect detection: After coating and drying, irradiate the wall surface with a laser, observe the fluorescence emission effect, and ensure there is no significant reflection; irradiate the wall surface from different angles, take multiple groups of images, and analyze whether the fluorescence of the coating is uniform; if the difference in luminous intensity is too large, appropriately re-coat or adjust the coating thickness until a uniform effect is achieved.

[0029] As a further improvement of the present invention, step 3 is specifically as follows:

[0030] Particle seeding: Add DEHS tracer particles at the position of the wind tunnel power section, turn on the flow field to evenly distribute the particles; check the particle density through preliminary imaging to ensure uniform particle distribution;

[0031] Laser intensity calibration: Adjust the intensities of the inner and outer region lasers, observe the uniformity of the laser spot, and ensure uniform light intensity distribution in the imaging area; synchronously adjust the laser pulse frequency according to the camera shooting frequency to ensure stable light illumination for each shot;

[0032] Image stitching detection: Test the camera stitching effect, eliminate the stitching seams by adjusting the overlap and alignment of the adjacent lens fields of view, and make the image present a seamless effect; after completing the stitching, detect the overall brightness and clarity of the image to ensure the final stitched image is uniform.

[0033] As a further improvement of the present invention, step 4 is specifically as follows:

[0034] Particle injection and experiment start: Transport the dyed glass bead particles to the experimental area through air flow, and the injection speed of the particles matches the fluid speed set in the experiment; during the experiment, control the air flow speed by adjusting the output power of the air pump;

[0035] Image acquisition and data processing: After the fluid starts to move, start the laser and camera synchronization controller, and start acquiring images at the set frequency; continuously acquire exposure images during the experiment duration to obtain paired image data; during the acquisition process, monitor the image quality in real time to ensure that the image pairs are clear, have high contrast, and the particle distribution is uniform;

[0036] Data preprocessing: Remove the image background, segment the particle phase and fluid phase in the image, extract data respectively, after separate phase processing, extract the data of the particle phase and fluid phase respectively to prepare for the velocity field calculation, use a filtering algorithm to enhance the image contrast, and perform coordinate calibration on the image;

[0037] Calculating the velocity field by cross-correlation algorithm: Divide the image into regions of a fixed size, perform cross-correlation operations on the image pairs, determine the average particle displacement within each region, and construct the displacement distribution of the entire flow field; divide the regional displacement by the exposure interval to obtain the velocity vector field of each region, and combine them to generate the complete fluid velocity field;

[0038] Data Saving and Post-Processing: Save the velocity vector field data in a file format suitable for subsequent analysis and visualization; check the accuracy of the velocity field data, compare the velocity distributions in different regions, identify anomalies, and optimize the acquisition process.

[0039] The beneficial effects of the present invention are as follows:

[0040] 1. In the study of the gas-solid two-phase boundary layer, high requirements are placed on measurement accuracy and spatial resolution. Especially in the complex flow field of the boundary layer, synchronous measurement of the inner and outer regions is required to accurately describe the flow field. The present invention uses a high-spatial-resolution camera and a large-field-of-view camera system, combined with the synchronous triggering technology of a laser, to perform synchronous measurement of the inner and outer regions to achieve high-precision detection of the gas-solid two-phase boundary layer.

[0041] 2. The method proposed by the present invention can effectively reduce the reflection near the wall surface, effectively improve the signal-to-noise ratio of the near-wall flow data, improve the measurement accuracy, and the high-resolution camera near the wall can measure the viscous sublayer of the boundary layer and can measure the near-wall region more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic structural diagram of the measurement device in the embodiment of the present invention;

[0043] Figure 2 is a comparison diagram of the measurement effects in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The embodiments of the present invention will be described in detail below with reference to the drawings.

[0045] Embodiment

[0046] A method for synchronous measurement of the inner and outer regions of a gas-solid two-phase boundary layer, comprising:

[0047] 1. High-temperature calcination of fluorescent glass microspheres:

[0048] Physical and chemical effects during the calcination process: Calcination is carried out in a high-temperature environment of 600 - 800 degrees Celsius, mainly to cause minor changes in the surface structure of the glass beads. At high temperatures, fine pores and roughness will appear on the surface of the glass beads, which is beneficial to the adsorption of the dye. In addition, calcination can remove the organic matter or impurities that may exist on the particle surface, improve the purity of the particles, and ensure more uniform binding of the dye to the particle surface.

[0049] Operation steps:

[0050] Preheating stage: Set the high-temperature furnace to 600 degrees Celsius and keep it at a constant temperature for 10 minutes to ensure the stability of the furnace temperature.

[0051] Calcination: Evenly spread the glass beads in a high-temperature resistant ceramic crucible. The filling thickness of the crucible should not exceed 5 mm to ensure that each glass bead is evenly heated. Place the crucible in the furnace and calcine for 2 hours.

[0052] Temperature increase control: During the calcination process, check the temperature curve every 15 minutes to ensure that the temperature fluctuation does not exceed ±10 degrees Celsius, so as to prevent the internal structure of the glass beads from changing due to excessive temperature.

[0053] Cooling: After the calcination is completed, slowly cool down to avoid cracks in the glass beads caused by sudden temperature drop. After cooling to room temperature, take out the glass beads for standby.

[0054] Selection of dye and its principle: Kiton 620 is a highly efficient fluorescent dye with good light stability and non-toxicity, suitable for long-term experiments. Kiton 620 can absorb laser energy and emit fluorescence, and this property can significantly enhance the visibility of particles under laser irradiation in PIV measurement.

[0055] 1.1 Preparation of staining solution:

[0056] Prepare a 5 - 10% Kiton 620 solution according to the recommended use concentration of the dye. Ethanol also needs to be added to the solution as a stabilizer, and the volume ratio of ethanol is 10 - 20% to improve the dispersion of the dye in the solution and avoid precipitation.

[0057] The pH value of the solution should be adjusted between 4 - 5 to ensure the best binding effect of the dye molecules on the surface of the glass beads in a neutral environment. Use a pH meter to monitor the acidity and alkalinity of the solution in real time, and make fine adjustments by adding NaOH or HCl if necessary.

[0058] 1.2 Staining process:

[0059] Add the calcined glass beads to the staining solution and mix them at a ratio of 1:10 of the particle weight to the solution volume. The solution volume should be reasonably configured according to the number of particles to ensure that all particles are fully immersed.

[0060] Start the stirring device in the staining reactor, and control the stirring speed at 100 - 200 revolutions per minute. The staining reaction is carried out at room temperature, and the reaction time is 30 minutes to 1 hour to ensure that the dye fully adheres to the surface of the glass beads.

[0061] During the staining process, take a small amount of samples every 10 minutes to observe the staining effect and check the uniformity and adhesion strength of the color on the particle surface.

[0062] 1.3 Cleaning and drying after staining:

[0063] After the staining is completed, stop stirring and remove the particles from the solution. Wash the particles with deionized water multiple times, usually 5 times. Assist with an ultrasonic cleaner during each wash to ensure that the stain is completely bound to the particle surface and to remove unbound stain.

[0064] The washed particles are dried in an oven at 50 - 60 degrees Celsius for 4 hours. This process can further remove residual moisture and prevent the particles from adhering to the experimental equipment due to wetness during subsequent experiments.

[0065] 1.4 Detection of staining effect:

[0066] The dried stained particles need to be detected by a fluorescence microscope to confirm the uniformity and stability of the staining. Observe the fluorescence emission effect of the particles under illumination with an excitation wavelength of 620 nm. The particles with uniform staining should exhibit consistent red fluorescence with stable brightness and no obvious fluorescence decay.

[0067] 2. Installation and testing of experimental instruments:

[0068] 2.1 Selection and installation of laser light source:

[0069] 2.1.1 Selection of laser:

[0070] Model selection: Select a high - energy pulsed laser according to the experimental needs. Set the pulse energy to 200 mJ and 500 mJ to ensure that when penetrating the gas - solid two - phase flow, the light scattering intensity is sufficient, making the tracer particles in the flow field clearly visible during imaging.

[0071] Test energy: Before the experiment, adjust the laser energy level and conduct tests to ensure that the two finally selected lasers can maintain imaging clarity under different flow rate conditions.

[0072] 2.1.2 Wavelength setting:

[0073] Selected wavelength: Set the laser wavelength at 532 nm (green light), which matches the absorption peak of Kiton 620 fluorescent dye and can effectively excite orange - red fluorescence.

[0074] Signal - to - noise ratio verification: At the initial stage of the experiment, test the fluorescence effect in a small sample area and observe whether the signal - to - noise ratio meets the requirements. If the fluorescence intensity is found to be uneven, the laser energy or dye concentration can be appropriately adjusted.

[0075] 2.1.3 Installation of optical fiber:

[0076] Connection and fixation: Connect one end of the optical fiber to the laser and install the other end on the bracket above the experimental area. The stable installation of the optical fiber can avoid beam deviation.

[0077] Angle and Height Adjustment: Adjust the height of the bracket and the angle of the fiber optic end so that the laser beam evenly covers the experimental area. Fine-tune the height and angle of the fiber optic output end according to the flow field size to obtain the best illumination range and intensity distribution.

[0078] Uniformity Detection: After the installation is completed, use an imaging device to collect the irradiation images to ensure that the laser irradiation is uniform and there are no significant brightness differences.

[0079] The structural schematic diagram of the measuring device is as Figure 1 shown.

[0080] 2.2 Installation of Fluorescent Coated Wall:

[0081] 2.2.1 Coating Material Selection:

[0082] Material Preparation: Mix the water-based fluorescent paint Kiton 620 with a polymer to prepare a uniform paint solution. The Kiton 620 fluorescent material can emit strong fluorescence under 532nm laser irradiation.

[0083] Solution Stability Test: Conduct a stability test on the paint solution before the experiment to observe whether there is precipitation or caking to ensure the uniformity of the fluorescence intensity.

[0084] 2.2.2 Coating Steps:

[0085] Spraying: Use professional spraying equipment to evenly spray the fluorescent paint on the wall of the experimental device, ensuring that the coating thickness is maintained between 10 - 50 microns. This thickness can not only ensure the fluorescence intensity but also make the coating durable.

[0086] Thickness Control: Use a thickness gauge to check the uniformity of the coating and measure the thickness in different areas to ensure consistency. Re-coat or adjust the uneven parts.

[0087] 2.2.3 Fluorescent Effect Detection:

[0088] Irradiation Test: After the coating is dry, irradiate the wall with a laser and observe the fluorescence emission effect to ensure there is no significant reflection.

[0089] Uniformity Detection: Irradiate the wall from different angles, take multiple groups of images, and analyze whether the fluorescence of the coating is uniform. If the luminous intensity difference is too large, re-coat or adjust the paint thickness appropriately until a uniform effect is achieved.

[0090] 2.3 Installation and Calibration of the Camera System:

[0091] 2.3.1 System Composition:

[0092] Camera Configuration: In this experiment, four 50mm fixed-focus cameras and one 200mm telephoto lens camera were configured. A 2x teleconverter was added to form a complete imaging system.

[0093] Synchronous Connection: Connect each camera to the synchronous controller to ensure accurate synchronous shooting during the laser pulse, so as to avoid data errors caused by image misalignment.

[0094] 2.3.2 Installation of Fixed-Focus Cameras:

[0095] Arrangement of Outer Region Cameras: Arrange the four 50mm fixed-focus cameras evenly around the experimental area. Adjust the height according to the size of the experimental flow field so that the viewing angle of the cameras covers the entire outer region flow field.

[0096] Focal Length Calibration: After installation, start the calibration program of the camera and use a calibration board to adjust the focal length of the camera to ensure that the image is distortion-free.

[0097] Imaging Scale Calibration: During the calibration process, each camera takes a grid image of a known size, and uses the calibration to calculate the imaging scale of each camera to ensure the accuracy of the data.

[0098] 2.3.3 Settings of Telephoto Lens and Teleconverter:

[0099] Arrangement in the Near-Wall Region: Install the 200mm telephoto lens and the 2x teleconverter on the inner wall of the experimental area, which is dedicated to shooting the tiny flow details in the near-wall flow field.

[0100] Magnification Calibration: Adjust the magnification of the teleconverter to ensure that the entire range of the near-wall region is covered and the imaging is clear. Shoot the calibration board and perform accuracy calibration so that the enlarged image corresponds to the actual size.

[0101] 2.4 Synchronous Debugging of Laser and Camera:

[0102] Connection and Frequency Setting: Connect the laser and the camera system, and set the controller frequency to 4Hz to ensure 4 pulse shots per second. According to the experimental requirements, connect the camera systems and the laser in the inner and outer regions to the synchronous control system, and adjust the trigger signal through the timing control module. The 50mm lens camera is synchronized with the 500mJ laser, and the telephoto lens camera is synchronized with the 200mJ laser to ensure that the pulses of the 200mJ and 500mJ lasers are strictly synchronized with the exposure instant of the camera.

[0103] 2.4.2 Trigger Delay Adjustment:

[0104] Delay Correction: Before the experiment starts, gradually adjust the trigger delay parameter of the controller to ensure that the opening time of the laser pulse and the camera shutter match precisely.

[0105] Synchronous verification: Conduct multiple test shootings to confirm that the laser irradiation and camera exposure are completely synchronous, avoiding signal loss. Adjust the delay parameter until the imaging is clear and the image signal is error-free.

[0106] 2.5 Tracer particle seeding and laser calibration:

[0107] 2.5.1 Particle seeding:

[0108] Seeding steps: Add DEHS tracer particles at the position of the wind tunnel power section and turn on the flow field to evenly distribute the particles.

[0109] Density detection: Check the particle density through preliminary imaging to ensure uniform particle distribution. If it is not uniform, adjust the wind tunnel parameters to optimize the particle distribution.

[0110] 2.5.2 Laser intensity calibration:

[0111] Regional intensity adjustment: Adjust the intensity of the inner and outer zone lasers, observe the uniformity of the laser spot, and ensure uniform light intensity distribution in the imaging area.

[0112] Pulse frequency adjustment: Synchronously adjust the laser pulse frequency according to the camera shooting frequency to ensure stable light illumination for each shooting.

[0113] 2.5.3 Image stitching detection:

[0114] Stitching algorithm optimization: Test the camera stitching effect, eliminate the stitching seam by adjusting the overlap and alignment of adjacent lens fields of view, and make the image present a seamless effect.

[0115] Imaging uniformity inspection: After completing the stitching, detect the overall brightness and clarity of the image to ensure the uniformity of the final stitched image.

[0116] 3. Data acquisition and image processing:

[0117] 3.1 Particle injection and experiment start:

[0118] Particle injection device: Use the particle injection device to transport the dyed glass bead particles to the experimental area through air flow. The injection speed of the particles needs to match the set fluid speed of the experiment to ensure uniform distribution of the particles in the experimental area without affecting the natural flow characteristics of the gas-solid two-phase flow.

[0119] Airflow speed control: The airflow speed used in the experiment ranges from 15 meters per second, and the airflow speed is precisely controlled by adjusting the output power of the air pump. The accuracy of the airflow speed should be maintained within ±0.1 meters per second to ensure repeatability under different experimental conditions.

[0120] 3.2 Image acquisition and data processing process:

[0121] 3.2.1 Image Acquisition:

[0122] Start Acquisition: After the fluid starts to move, start the laser and camera synchronization controller and start acquiring images at the set frequency.

[0123] Continuous Acquisition: During the experimental duration, continuously acquire A and B exposure images to obtain paired image data, preparing for subsequent cross-correlation processing.

[0124] Real-time Monitoring: During the acquisition process, monitor the image quality in real time to ensure that the image pairs are clear, have high contrast, and have uniform particle distribution. If problems are found, adjust the laser and camera parameters in a timely manner.

[0125] 3.2.2 Data Preprocessing:

[0126] Background Removal: Remove the background from the images to reduce background light and noise and improve the contrast of the tracer particles.

[0127] Two-parameter Phase Separation:

[0128] Particle-fluid Phase Separation: Segment the particle phase and fluid phase in the images and extract the data separately to support subsequent analysis.

[0129] Data Extraction: After phase separation processing, extract the data of the particle phase and fluid phase separately to prepare for velocity field calculation.

[0130] Image Enhancement: Use a filtering algorithm to enhance the image contrast to ensure clear particle edges for further analysis.

[0131] Image Calibration: Calibrate the coordinates of the images so that each pixel corresponds to the actual physical position to ensure that the data matches the true flow field size.

[0132] 3.2.3 Cross-correlation Algorithm for Calculating the Velocity Field:

[0133] Region Division: Divide the images into regions of a fixed size (interrogation windows) to facilitate the calculation of particle displacement for each region.

[0134] Cross-correlation Calculation: Perform cross-correlation operations on the image pairs to determine the average particle displacement within each region and construct the displacement distribution of the entire flow field.

[0135] Velocity Field Calculation: Divide the regional displacement by the exposure interval to obtain the velocity vector field for each region and combine them to generate the complete fluid velocity field.

[0136] 3.2.4 Data Saving and Post-processing:

[0137] Data Storage: Save the velocity vector field data in a file format suitable for subsequent analysis and visualization.

[0138] Precision analysis: Check the accuracy of the velocity field data, compare the velocity distributions in different regions, identify anomalies, and optimize the acquisition process.

[0139] The obtained comparison pictures are as Figure 2 shown.

[0140] The above-described embodiments only represent the specific implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. An apparatus for synchronously measuring the inner and outer regions of a gas-solid two-phase boundary layer, characterized in that It includes an experimental area for passing through a gas-solid two-phase flow. A high-energy pulsed laser is provided on the experimental area. The inner wall of the experimental area is sprayed with a fluorescent coating. Multiple fixed-focus lens cameras are provided outside the experimental area. A long-focus lens and a 2X teleconverter are provided on the inner wall of the experimental area. And both the long-focus lens camera and the fixed-focus lens camera are connected to a synchronous controller.

2. The device for synchronously measuring the inner and outer regions of the gas-solid two-phase boundary layer according to claim 1, wherein The high-energy pulsed laser is installed on the experimental area through an optical fiber.

3. A method for synchronously measuring the inner and outer regions of a gas-solid two-phase boundary layer, characterized in that It includes the following steps: Step 1: Calcinate and dye glass bead particles. Step 2: Install the device for synchronous measurement of the inner and outer regions of the gas-solid two-phase boundary layer as described in claim 1 or 2, and spray a fluorescent coating on the inner wall of the measuring device. Step 3: Trace particle seeding and laser calibration. Step 4: Data acquisition and image processing.

4. The method for synchronously measuring the inner and outer regions of the gas-solid two-phase boundary layer according to claim 3, wherein In Step 1, the calcination of the glass bead particles is specifically as follows: Preheating stage: Set the high-temperature furnace to a preset temperature and maintain a constant temperature for a preset time to ensure the stability of the temperature in the furnace. Calcination: Evenly spread the glass bead particles on a high-temperature-resistant ceramic crucible, and place the ceramic crucible in the furnace for calcination for a preset time. Temperature increase control: During the calcination process, check the temperature curve every fixed time to ensure that the temperature fluctuation does not exceed the preset threshold. Cooling: After the calcination is completed, slowly cool down to avoid cracks in the glass beads caused by sudden temperature drop. After cooling to room temperature, take out the glass beads for standby.

5. The method for synchronously measuring the inner and outer regions of a gas-solid two-phase boundary layer according to claim 4, wherein In Step 1, the dyeing of the glass bead particles is specifically as follows: Prepare the dyeing solution: According to the recommended usage concentration of the dyeing agent, configure a 5-10% Kiton 620 solution. Add ethanol as a stabilizer to the solution. The volume ratio of ethanol is 10-20% to improve the dispersion of the dyeing agent in the solution and avoid precipitation. Adjust the pH value of the solution to between 4 and 5. Use a pH meter to monitor the acidity and alkalinity of the solution in real time, and fine-tune the acidity and alkalinity by adding NaOH or HCl. Dyeing process: Add the calcined glass bead particles to the dyeing solution and mix them in a ratio of 1:10 by particle weight to solution volume. Start the stirring device in the dyeing reactor, and control the stirring speed at 100-200 revolutions per minute. The dyeing reaction is carried out at room temperature, and the reaction time is 30 minutes to 1 hour to ensure that the dyeing agent is fully attached to the surface of the glass beads. During the dyeing process, take a small amount of samples every 10 minutes to observe the dyeing effect and check the uniformity and adhesion strength of the color on the particle surface. Washing and drying: After the dyeing is completed, stop stirring and take out the particles from the solution. Wash the particles multiple times with deionized water, and use an ultrasonic cleaner to assist each time to ensure that the dyeing agent is completely combined on the particle surface and remove the unbound dyeing agent. The washed particles are dried in an oven at 50-60 degrees Celsius.

6. The method for synchronously measuring the inner and outer regions of the gas-solid two-phase boundary layer according to claim 5, wherein It also includes detecting the dyeing effect: Detect by a fluorescence microscope and observe the fluorescence emission effect of the glass bead particles under light with an excitation wavelength of 620 nm.

7. The method for synchronously measuring the inner and outer regions of the gas-solid two-phase boundary layer according to claim 3, characterized in that, In Step 2, spraying the fluorescent coating on the inner wall of the measuring device is specifically as follows: Select coating material: Mix the water-based fluorescent paint Kiton 620 with a polymer to prepare a uniform paint solution. Before the experiment starts, conduct a stability test on the paint solution to observe whether there is precipitation or caking to ensure the uniformity of fluorescence intensity. Spraying: Use spraying equipment to evenly spray the fluorescent paint on the wall surface of the experimental area of the experimental device, ensuring that the coating thickness is maintained between 10 - 50 microns. Use a thickness gauge to check the uniformity of the coating and measure the thickness in different areas to ensure consistency. Re-coat or adjust the uneven parts. Fluorescence effect detection: After the coating dries, irradiate the wall surface with a laser and observe the fluorescence emission effect to ensure there is no significant reflection. Irradiate the wall surface from different angles, take multiple sets of images, and analyze whether the fluorescence of the coating is uniform. If the difference in luminous intensity is too large, appropriately re-coat or adjust the paint thickness until a uniform effect is achieved.

8. The method for synchronously measuring the inner and outer regions of the gas-solid two-phase boundary layer according to claim 3, wherein The specific steps of step 3 are as follows: Particle seeding: Add DEHS tracer particles at the position of the wind tunnel power section, start the flow field to evenly distribute the particles. Check the particle density through preliminary imaging to ensure uniform particle distribution. Laser intensity calibration: Adjust the intensities of the inner and outer zone lasers, observe the uniformity of the laser spot, and ensure uniform light intensity distribution in the imaging area. Synchronously adjust the laser pulse frequency according to the camera shooting frequency to ensure stable light for each shot. Image stitching detection: Test the stitching effect of the camera, eliminate the stitching seams by adjusting the overlap and alignment of the adjacent lens fields of view, and make the image present a seamless effect. After completion of stitching, detect the overall brightness and clarity of the image to ensure the uniformity of the final stitched image.

9. The method for synchronously measuring the inner and outer regions of the gas-solid two-phase boundary layer according to claim 8, characterized in that, The specific steps of step 4 are as follows: Particle injection and experiment start: Transport the dyed glass bead particles to the experimental area through air flow, and the injection speed of the particles matches the fluid speed set in the experiment. During the experiment, control the air flow speed by adjusting the output power of the air pump. Image acquisition and data processing: After the fluid starts to move, start the laser and camera synchronization controller, and start acquiring images at the set frequency. Continuously acquire exposure images within the experimental duration to obtain paired image data. During the acquisition process, monitor the image quality in real time to ensure that the image pairs are clear, have high contrast, and uniform particle distribution. Data preprocessing: Remove the image background, segment the particle phase and fluid phase in the image, extract data respectively. After phase separation processing, extract the data of the particle phase and fluid phase respectively to prepare for the calculation of the velocity field. Use a filtering algorithm to enhance the image contrast and calibrate the coordinates of the image. Calculate the velocity field using the cross-correlation algorithm: Divide the image into regions of a fixed size, perform cross-correlation operations on the image pairs, determine the average particle displacement within each region, and construct the displacement distribution of the entire flow field. Divide the regional displacement by the exposure interval to obtain the velocity vector field of each region, and combine them to generate the complete fluid velocity field. Data saving and post-processing: Save the velocity vector field data in a file format suitable for subsequent analysis and visualization. Check the accuracy of the velocity field data, compare the velocity distributions in different regions, identify anomalies, and optimize the acquisition process.

Images