Device and method for measuring dust concentration distribution at inlet of aero-engine

Abstract

The invention discloses a device and method for measuring dust concentration distribution at an inlet of an aero-engine, and belongs to the field of aero-engine sand swallowing tests, the device comprises a pulse laser light source, a shaping module, an optical image acquisition module and a data post-processing module, the pulse laser light source is arranged at a preset position around the aero-engine and is used for emitting laser beams, and the shaping module is used for shaping the laser beams; the aero-engine is located in a sand dust environment to be detected; the shaping module is used for receiving the laser beam and outputting a sheet-shaped beam; the optical image acquisition module is used for receiving coherent scattered light emitted by the grit in the irradiation area of the flaky light beam to form a laser speckle image, and transmitting the obtained laser speckle image to the data post-processing module; and the data post-processing module processes the laser speckle image by adopting an inlet sand dust concentration measurement algorithm to obtain the concentration distribution of the inlet sand dust of the aero-engine. The device is simple in structure, and is suitable for measuring the sand dust concentration distribution at the inlet in the sand swallowing experiments of aero-engines with different sizes or stages.

Description

Technical Field

[0001] The present invention relates to the field of sand ingestion tests for aeroengines, and particularly to a device and method for measuring the sand and dust concentration distribution at the inlet of an aeroengine. Background Art

[0002] To ensure that an aeroengine can operate stably under harsh flight conditions with a large amount of sand and dust, such as desert environments and dusty weather encountered during takeoff, landing, and flight of an aircraft, the sand ingestion test has become one of the important test items for the design and finalization of new engines. In the sand ingestion test, a sand ingestion device is used to inject test sand and dust into the aeroengine to simulate as much as possible the state of the engine inhaling sand and dust during actual use. At present, the research on sand ingestion tests mainly focuses on the influence of sand and dust particles on the performance of turboprop / turbofan engines. Limited by the existing measurement technology conditions, the sand intake in the sand ingestion test can only be inversely obtained based on relevant parameters such as the travel of the feeding mechanism and the particle size range of the sand and dust, and the sand and dust concentration distribution and instantaneous sand intake mass flow rate in the cross-section near the engine inlet cannot be obtained, which limits the data breadth of engine performance testing.

[0003] The sand ingestion device consists of a sand bucket, a sand scraping mechanism, a feeding mechanism, a mixer, a distributor, a compressed air pipeline, a mounting bracket, and a measurement and control system. Its working principle is as follows: The sand scraping mechanism driven by the feeding mechanism rotates uniformly and descends uniformly in the sand bucket, so that the sand and dust are blown into the mixer from the sand outlet pipeline by high-pressure air; the sand and dust uniformly mixed with air are transported to the distributor through several hoses and ejected from the nozzles. The sand and dust are diffused through the nozzles to completely cover the engine air intake grid (diameter ≥ 800 mm), and then are sucked into the engine intake duct to complete the sand ingestion process. Among them, the sand intake is inversely obtained from the travel of the feeding mechanism and the instantaneous rotational speed of the driving motor. The sand intake obtained by the above method only represents the total mass of all the sand and dust inhaled by the aeroengine during a certain time interval, and the reliability of the inversion algorithm is lower than that of the visualization measurement method. Therefore, for the actual requirements such as the measurement of the total sand intake, the spatial distribution of sand and dust, and the instantaneous distribution characteristics of sand and dust in the sand ingestion test, it is necessary to develop a special measurement technology.

[0004] At present, for the measurement technology of the concentration distribution of discrete phases such as solid particles, visualization image measurement technologies such as holography and shadow method are generally adopted. As many particles as possible in the field of view are captured by a camera, and then accurate concentration distribution information of the discrete phase is obtained. Among them, the holography method is developed based on theories such as Huygens-Fresnel diffraction theory and light scattering theory. Its principle is that a laser irradiates a cloud field to form scattered light, and a holographic dry plate or a camera is used to record the interference fringes generated by the scattered light and the original laser. The particle position and particle size information are obtained by optical reconstruction or numerical reconstruction. The shadow method captures particles based on the difference in the light transmission characteristics of different media, and then uses image processing technology to obtain the particle size and distribution information, which has the advantages of simple principle, convenient testing, and low cost. However, the above methods cannot be directly applied to the sand ingestion test of aero-engines. On the one hand, both the holography method and the shadow method require the optical axes of the light source end and the camera acquisition end to coincide. When measuring the sand dust distribution at the engine inlet section, this layout will inevitably affect the engine intake air flow, and then lead to the deviation of the ground simulation conditions of the sand ingestion test from the actual engine operating conditions. On the other hand, one of the measurement / imaging principles of the holography method and the shadow method is to perform two-dimensional compression on the imaging area of the lens. Therefore, there are a large number of particle stacks and interactions in the image, which makes it impossible to accurately obtain the particles and their distribution in a single plane section.

[0005] Therefore, it is necessary to carry out research on the measurement technology of the sand dust concentration distribution and the development of measurement devices at the inlet of aero-engines for the sand ingestion test of aero-engines. Summary of the Invention

[0006] The purpose of the present invention is to provide a device and method for measuring the sand dust concentration distribution at the inlet of aero-engines, so as to solve problems such as the low reliability of the backtracking algorithm for calculating the sand ingestion amount in traditional sand ingestion experiments and the inability to monitor or obtain the sand dust concentration at different cross-sections at the inlet during the experiment.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions: A device for measuring the sand dust concentration distribution at the inlet of aero-engines includes a pulsed laser light source, a shaping module, an optical image acquisition module, and a data post-processing module: The pulsed laser light source is placed at a preset position around the aero-engine and is used to emit a laser beam, and the aero-engine is located in the sand dust environment to be measured; The shaping module is used to receive the laser beam and output a sheet-shaped beam; The optical image acquisition module is used to receive the coherent scattered light emitted by the sand and gravel in the area irradiated by the sheet-shaped beam, form a laser speckle image, and transmit the obtained laser speckle image to the data post-processing module; The data post - processing module processes the laser speckle image using an imported sand and dust concentration measurement algorithm to obtain the sand and dust concentration distribution at the inlet of the aero - engine.

[0008] Further, the optical image acquisition module includes a distributed optical collector and a timing trigger controller. The timing trigger controller is used to control the distributed optical collector to capture the coherent scattered light emitted by the gravel, forming a laser speckle image. The distributed optical collector includes several cameras and telecentric camera lenses that cooperate with the cameras.

[0009] Further, the shaping module includes a zero - order wave plate, a reflector, a plano - convex cylindrical lens, and a plano - concave cylindrical lens arranged in sequence. The shaping module is used to make the plane where the sheet - shaped light beam is located perpendicular to the optical axis of the camera.

[0010] Further, the data post - processing module is a computer with an imported sand and dust concentration measurement algorithm built - in. The imported sand and dust concentration measurement algorithm is specifically as follows: Input the laser speckle image obtained in the actual scene into a pre - established gravel morphology and particle size inversion model to obtain the morphology and particle size information of the gravel. Based on the morphology and particle size information of the gravel, use basic geometric shapes to model the gravel and calculate the equivalent mass. Taking the center position at the inlet of the aero - engine as a reference to construct a reference coordinate system, divide the laser speckle image into grids according to the reference coordinate system, determine the grid size according to the maximum particle size of the gravel, convert the number of gravels and the equivalent mass in each grid into values between 0 and 1, and then obtain a statistical chart of the relative concentration of the gravel. Obtain the sand and dust concentration distribution at the inlet of the aero - engine according to the statistical chart of the relative concentration of the gravel.

[0011] Further, the establishment process of the gravel morphology and particle size inversion model is specifically as follows: Based on the mapping relationship between the pre - obtained gravel morphology and the laser speckle image, obtain a gravel speckle simulation calculation model. Use the maximum inscribed rhombus method to automatically generate several gravel morphology images as a dataset of irregular - shaped gravel morphologies. Import the dataset of irregular - shaped gravel morphologies as input into the gravel speckle simulation calculation model, and output several laser speckle images corresponding to the gravel morphology images to obtain a dataset of irregular - shaped gravel speckle images. Use a deep - learning network to train the dataset of irregular - shaped gravel speckle images to establish a gravel morphology and particle size inversion model.

[0012] Furthermore, the mapping relationship between the gravel morphology and the laser speckle image is obtained by a calibration device, which includes an ultrasonic levitation stage, a speckle image collector, and a gravel morphology collector. The ultrasonic levitation stage is installed within the imaging focal planes of the speckle image collector and the gravel morphology collector, and the force field center of the ultrasonic levitation stage is aligned with the center of the imaging area and the irradiation area of the sheet beam. The ultrasonic levitation stage includes an upper part and a lower part of the ultrasonic levitation stage, and the upper and lower parts of the ultrasonic levitation stage are used to levitate gravel with multiple morphologies. The gravel morphology and the speckle image are respectively collected by the gravel morphology collector and the speckle image collector to obtain the mapping relationship between the gravel morphology and the speckle image.

[0013] A method for measuring the sand and dust concentration distribution at the inlet of an aeroengine includes the following steps: A laser beam is emitted by a pulsed laser light source placed at a preset position around the aeroengine to be measured. The laser beam is received by a shaping module and outputs a sheet beam. The coherent scattered light emitted by the gravel within the irradiation area of the sheet beam is received by an optical image acquisition module to form a laser speckle image, and the obtained laser speckle image is transmitted to a data post-processing module. The data post-processing module processes the speckle image to obtain the sand and dust concentration distribution at the inlet of the aeroengine.

[0014] Furthermore, the process of the data post-processing module processing the laser speckle image to obtain the sand and dust concentration distribution at the inlet of the aeroengine is specifically as follows: The laser speckle image obtained in the actual scene is input into a pre-established gravel morphology and particle size inversion model to obtain the morphology and particle size information of the gravel. Based on the morphology and particle size information of the gravel, the gravel is modeled using basic geometric shapes and the equivalent mass is calculated. Taking the center position of the aeroengine inlet as a reference to construct a reference coordinate system, the speckle image is divided into grids according to the reference coordinate system, the grid size is determined according to the maximum particle size of the gravel, and the number of gravels and the equivalent mass within each grid are converted into values between 0 and 1, and then a statistical chart of the relative concentration of the gravel is obtained. The sand and dust concentration distribution at the inlet of the aeroengine is obtained according to the statistical chart of the relative concentration of the gravel.

[0015] Furthermore, the establishment process of the gravel morphology and particle size inversion model is specifically as follows: Based on the mapping relationship between the gravel morphology and the laser speckle image obtained in advance, a gravel speckle simulation calculation model is obtained. Automatically generate a number of gravel morphology images using the maximum inscribed rhombus method as a dataset of irregular gravel morphology, and import the dataset of irregular gravel morphology as input into the gravel speckle simulation calculation model to output a number of laser speckle images corresponding to the gravel morphology images, obtaining a dataset of irregular gravel speckle images; Use a deep learning network to train the dataset of irregular gravel speckle images and establish an inversion model for gravel morphology and particle size.

[0016] Furthermore, the mapping relationship between the gravel morphology and the laser speckle image is obtained through a calibration device. The calibration device includes an ultrasonic suspension table, a speckle image collector, and a gravel morphology collector. The ultrasonic suspension table is installed within the imaging focal plane of the speckle image collector and the gravel morphology collector, and the force field center of the ultrasonic suspension table is aligned with the center of the imaging area and the irradiation area of the sheet beam; The ultrasonic suspension table includes an upper part of the ultrasonic suspension table and a lower part of the ultrasonic suspension table, and the upper part and the lower part of the ultrasonic suspension table are used to suspend gravel with multiple morphologies; Collect the gravel morphology and the speckle image through the gravel morphology collector and the speckle image collector respectively to obtain the mapping relationship between the gravel morphology and the speckle image.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a device for measuring the sand and dust concentration distribution at the inlet of an aeroengine. Based on laser irradiation of irregular gravel, the coherent scattered light propagates to the far field to generate a laser speckle image. Using the inlet sand and dust concentration measurement algorithm, high-precision measurement of the gravel morphology / particle size and sand and dust concentration distribution at the inlet section of the aeroengine during the sand swallowing experiment is realized, thereby solving problems such as the low reliability of the backtracking algorithm for calculating the sand swallowing amount in traditional sand swallowing experiments and the inability to monitor or obtain the sand and dust concentration at different cross-sections at the inlet. The present invention can be used to improve the design ability of the sandblasting device used in the sand swallowing experiment. In addition, the present invention adopts a visualization measurement technology, the measurement result has high precision, the measurement process has a clear physical basis, and due to the modular design of the present invention, the structure is simple, convenient to carry, and suitable for measuring the sand and dust concentration distribution at the inlet during the sand swallowing experiment of aeroengines of different sizes or stages.

[0018] Furthermore, by designing the structure of the shaping module, the plane where the sheet beam is located is perpendicular to the optical axis of the camera, so that the imaging position is more than 1.5 m away from the inlet of the aeroengine. In this way, the influence of the measurement device on the inlet air flow of the aeroengine can be significantly reduced, and thus the sand swallowing experiment can be more in line with the actual harsh environmental conditions.

[0019] Furthermore, a sand grain speckle simulation calculation model is obtained through the mapping relationship between the sand grain morphology and the laser speckle image. By learning and training the sand grain speckle simulation calculation model, a sand grain morphology and particle size inversion model is obtained. Based on the sand grain morphology and particle size inversion model for measurement, it is possible to calculate the true morphology and particle size of the sand grains using the speckle imaging principle, and it is also possible to identify or detect smaller micro sand grains compared to traditional image measurement techniques at a far field (imaging distance > 1500 mm), thereby improving the test accuracy and application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings of the specification are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0021] Figure 1 is a structural diagram of the device for measuring the sand and dust concentration distribution at the inlet of an aeroengine according to the present invention; Figure 2 is a structural diagram of the calibration device according to the present invention; Figure 3 is a structural diagram of the distributed optical collector according to the present invention; Figure 4 is a specific implementation diagram of the sand and dust concentration distribution in the aeroengine sand ingestion test according to the present invention; Figure 5 is an algorithm step diagram of the sand grain morphology and particle size inversion model according to the present invention; Figure 6 is an algorithm step diagram of the inlet sand and dust concentration measurement algorithm according to the present invention.

[0022] Among them, 1. Short pulse width low-frequency laser; 2. Air gap zero-order wave plate; 3. 532 nm laser mirror; 4. 532 nm laser plano-convex cylindrical lens; 5. 532 nm laser plano-concave cylindrical lens; 6. Ultrasonic suspension table; 7. Sheet beam; 8. Sand grain coherent scattered light; 9. Distributed optical collector; 10. Timing trigger controller; 11. Computer; 12. Speckle image collector; 13. Sand grain morphology collector; 14. Irregular sand grains; 15. Illumination light source; 16. Upper part of the ultrasonic suspension table; 17. Lower part of the ultrasonic suspension table; 18. Sand grain storage barrel; 19. Sand grain conveying pipe; 20. Sand grain fluidization section; 21. Sand grain dispersion pipe; 22. Harsh sand and dust environment; 23. Aeroengine inlet; 24. Pressure plate; 25. Support; 26. Support rod; 27. Distributed fixed bracket; 28. Telephoto camera lens; 29. Horizontal rotation bracket; 30. Vertical rotation bracket; 31. Camera. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0025] Embodiment 1 As Figure 1 shown, the present invention provides an optical device for measuring the sand and dust concentration distribution at the inlet of an aeroengine, including a pulsed laser light source, a shaping module, an optical image acquisition module, and a data post-processing module. In the sand and dust environment to be measured, the pulsed laser light source is placed at a preset position around the aeroengine to emit a laser beam. The shaping module is used to receive the laser beam and output a sheet-shaped beam 7. The optical image acquisition module is used to receive the coherent scattered light emitted by the sand and gravel within the irradiation area of the sheet-shaped beam 7 and transmit the obtained laser speckle image to the data post-processing module. The imported sand and dust concentration measurement algorithm built in the data post-processing module can quickly process the laser speckle image and accurately obtain the sand and dust concentration distribution at the inlet of the aeroengine. The shaping module includes several optical elements, and the optical elements include a zero-order wave plate, a reflector, a plano-convex cylindrical lens, and a plano-concave cylindrical lens arranged in sequence. Its function is to shape the circular output light spot into a sheet-shaped beam 7 (illumination area ≮0.64m 2 ), and make the sand and gravel in the illumination area emit high-intensity coherent scattered light. Refer to Figure 1 and Figure 3 , the optical image acquisition module is a distributed optical collector 9 and a timing trigger controller 10. The timing trigger controller 10 is used to control the distributed optical collector 9 to capture the coherent scattered light emitted by the sand and gravel to form a laser speckle image. The distributed optical collector 9 includes several cameras 31 (specifically, high-resolution CCD cameras can be used) and telecentric camera lenses 28 that cooperate with the cameras 31.

[0026] It further includes a calibration device, which includes an ultrasonic suspension stage 6, a speckle image collector 12, and a gravel morphology collector 13. The ultrasonic suspension stage 6 includes an upper part 16 and a lower part 17 of the ultrasonic suspension stage. Multiple-morphology gravel is arranged between the upper part 16 and the lower part 17 of the ultrasonic suspension stage. The size range of the gravel is 50μm - 3000μm. The morphology of the gravel includes regular circles, approximate circles, approximate regular polygons, and various irregular morphologies. The speckle image collector 12 is composed of an industrial lens and a high-resolution CCD (Charge Coupled Device) camera. The gravel morphology collector 13 is composed of a high-magnification morphology observation lens and a high-resolution CCD camera.

[0027] During use, the distance between the industrial lens and the inlet section of the aero-engine should be ≮120 cm, and the sheet-shaped light beam 7 output by the shaping module should be perpendicular to the optical axis of the telecentric camera lens 28 of the optical image acquisition module. Finally, the image data collected by the optical image acquisition module is transmitted to the data post-processing module through a communication optical cable, and the morphology, particle size, in-section dust concentration distribution, and instantaneous mass flow rate of the gravel are obtained through processing.

[0028] The main body of the data post-processing module is a high-performance computer 11. The detailed processing process of this data post-processing module is as follows: In the first step, rely on the calibration device to obtain the gravel morphology images of different gravels and the corresponding laser speckle images, and form a gravel speckle image-morphology database, that is, the mapping relationship between the gravel morphology and the speckle image; In the second step, develop a gravel speckle simulation calculation model based on the ray tracing method and the laser speckle imaging theory based on the mapping relationship between the gravel morphology and the speckle image; In the third step, use the maximum inscribed rhombus method to automatically generate a number of gravel morphology images, that is, a dataset of abnormal-shaped gravel morphologies, and import it as input into the gravel speckle simulation calculation model. This gravel speckle simulation calculation model will output the corresponding speckle image, and then a large number of speckle images corresponding to the gravel morphology images can be obtained, that is, a dataset of abnormal-shaped gravel speckle images; In the fourth step, use a deep learning network to train the dataset of abnormal-shaped gravel speckle images obtained in the third step above to establish a gravel morphology and particle size inversion model. The function of this gravel morphology and particle size inversion model is to process the input speckle image and directly output the corresponding gravel morphology and particle size information; In the fifth step, obtain the laser speckle image of the gravel in the actual scenario, input it into the gravel morphology and particle size inversion model, and obtain the morphology and particle size information of the gravel; In the sixth step, use basic geometric figures to model the abnormal-shaped gravel and calculate the equivalent mass; In the seventh step, a reference coordinate system is constructed based on the center position of the aero-engine inlet, and the speckle image is meshed accordingly. The mesh size is determined according to the maximum particle size of the sand and gravel in the experiment. The number of sand and gravel in each mesh and the equivalent mass are converted into values between 0 and 1, and then a statistical chart of the relative concentration of sand and gravel is obtained.

[0029] The present invention relies on the sheet beam 7 to induce the coherent scattered light of the abnormally shaped sand and gravel, and by means of the scattering light interference phenomenon during the far-field propagation of the coherent scattered light. On the one hand, the imaging thickness can be limited within the camera focal plane to avoid the additional influence of out-of-focus sand and gravel on the measurement; on the other hand, this method can measure tiny sand and gravel at a relatively long distance, thereby avoiding the influence of the measuring device on the inlet flow field of the aero-engine during the sand swallowing experiment and deviating from the actual process.

[0030] The pulsed laser light source, the shaping module, and the optical image acquisition module are the key components of the device of the present invention. Capturing the sand and gravel distribution image in a certain cross-section can be achieved by the following two different techniques.

[0031] In the first technical solution, the optical axes of the pulsed laser light source and the high-resolution CCD camera are coaxially arranged. When it is necessary to measure the sand and gravel distribution image in a certain cross-section, the focal plane is made to coincide with the cross-section by adjusting the lens of the high-resolution CCD camera, and then the pulsed laser light source is turned on and made to directly irradiate the high-resolution CCD camera. When the sand and gravel pass through the test area, a shadow area will appear simultaneously in the high-resolution CCD camera. Parameters such as the sand and gravel concentration distribution in the cross-section can be obtained by reading the area and position coordinates of the shadow area in the image. This solution has the advantages of simple optical system and flexible adjustment of the test cross-section; however, the halo of out-of-focus sand and gravel caused by the lens depth of field has a greater impact on the measurement results (especially at high concentrations), the imaging principle shows that the distance between the focusing plane and the lens should be very close when measuring sand and gravel, resulting in a greater impact on the inlet air flow of the aero-engine, and the arrangement direction of the pulsed laser light source is against the inlet air flow direction of the aero-engine, resulting in greater difficulty in fixing the pulsed laser light source. Therefore, it is not suitable for measuring the sand and dust concentration distribution in the aero-engine sand swallowing experiment.

[0032] In the second technical solution, the optical axes of the pulsed laser light source and the high-resolution CCD camera are perpendicular to each other by using a cross arrangement. When measuring the gravel distribution image in a certain cross-section, the sheet beam 7 and the lens focal plane are respectively adjusted to coincide with the measurement cross-section. The sheet beam 7 is used to induce the shaped gravel to emit coherent scattered light, and the high-resolution CCD camera captures the laser speckle image generated during the far-field propagation of the coherent scattered light. Based on the mapping relationship between the gravel morphology and the speckle image obtained by the calibration device, the morphology and particle size information of the gravel are measured, and parameters such as the gravel concentration distribution in the cross-section are obtained by reading the area and position coordinates of the shadow area in the speckle image. This solution includes a shaping optical path for the laser beam, and the layout is relatively complex. However, the pulsed laser light source and the shaping module can be arranged outside the air inlet flow area of the aero-engine, which can avoid interfering with the air flow. The far-field propagation characteristics of the coherent scattered light can improve the measurement accuracy of tiny gravel, and then the high-resolution CCD camera can be installed at a relatively far distance from the air inlet of the aero-engine to minimize the impact on the inlet air flow. Therefore, the second technical solution is adopted in the present invention.

[0033] The technical solution for measuring the sand and dust concentration distribution at the inlet of an aero-engine by using the above device is as follows: The main steps for measuring the sand and dust concentration distribution at the inlet of an aero-engine include: static calibration, establishing an inversion model for the gravel morphology and particle size, measurement debugging, sand swallowing environment simulation, image acquisition, concentration distribution determination, etc., specifically including the following steps: A. Static calibration: Two high-resolution CCD cameras are respectively installed in cooperation with an industrial lens and a high-power morphology observation lens. The optical axis of the industrial lens needs to be kept coincident with the central longitudinal axis of the air inlet flow of the aero-engine, and with the optical axis of the industrial lens as the reference, the optical axis of the high-power morphology observation lens is tilted at an angle of 1-2° to ensure that the centers of the imaging frames of the two high-resolution CCD cameras are aligned with the same spatial area. The ultrasonic suspension stage 6 is installed in the imaging focal plane of the high-resolution CCD camera, and the weightless area of the ultrasonic suspension stage 6 is aligned with the center of the imaging area and the irradiation area of the sheet beam 7. The ultrasonic suspension stage 6 includes an upper part 16 and a lower part 17 of the ultrasonic suspension stage. Gravels with different morphologies / sizes are placed in the weightless area of the ultrasonic suspension stage 6 (i.e., between the upper part 16 and the lower part 17 of the ultrasonic suspension stage) in multiple times, and the high-resolution CCD camera is controlled by the timing trigger controller 10 to capture and save the speckle image and the high-resolution gravel morphology image of the gravel; B. Construct a gravel morphology and particle size inversion model. First, rely on a calibration device to obtain gravel morphology images of different gravels and their corresponding laser speckle images, that is, a gravel speckle-morphology database, and then obtain the mapping relationship between the gravel morphology and the speckle image. Second, develop a gravel speckle simulation calculation model based on the ray tracing method and the laser speckle imaging theory based on the mapping relationship between the gravel morphology and the speckle image. Third, use the maximum inscribed rhombus method to automatically generate a large number of gravel morphology images, that is, a dataset of abnormal gravel morphologies, and import it as input into the gravel speckle simulation calculation model. This gravel speckle simulation calculation model will output the corresponding speckle image, and then a large number of speckle images corresponding to the gravel morphology images can be obtained, that is, a dataset of abnormal gravel speckle images. Then, use a deep learning network to train the dataset of abnormal gravel speckle images to establish a gravel morphology and particle size inversion model. The function of this gravel morphology and particle size inversion model is to process the input speckle image and directly output the morphology and particle size information of the corresponding gravel. C. Measurement and debugging. According to the requirement that the sheet beam 7 is perpendicular to the optical axis of the high-resolution CCD camera, arrange the whole composed of the pulsed laser light source and the shaping module and the optical image acquisition module in a split manner at a suitable position. Specifically, the laser beam is emitted from the pulsed laser light source, its polarization angle is adjusted by a zero-order wave plate, and its emission direction is adjusted by a reflector to align with the beam shaping part. The beam shaping part consists of a plano-convex cylindrical lens and a plano-concave cylindrical lens, and the optical axis is in the horizontal and vertical direction of the central longitudinal axis of the intake air flow of the aeroengine. By compressing the direction of the laser beam and x stretching the y direction, the output of the sheet beam 7 is realized, and its thickness is kept uniform in the area of 800 mm in length. Among them, the pulsed laser light source and the shaping module should ensure that the optical path part is not less than 50 cm away from the intake air flow area of the aeroengine, and the telephoto camera lens 28 of the high-resolution CCD camera in the optical image acquisition module is not less than 120 cm away from the inlet section of the aeroengine. D. Simulate the sand swallowing environment. After disassembling the calibration device, install the sand and dust supply and dispersion device, connect the required gas pipeline, and turn on the sand and dust supply and dispersion device. When it is observed that the sand and dust flow stably into the aeroengine inlet along with the intake air flow of the aeroengine, adjust the adjustment knob of the sand and dust supply and dispersion device, and observe whether the response of the sand and dust supply and dispersion device is normal and whether the particle size of the outflowing gravel changes. If everything is normal, keep the operating state. E. Image acquisition. Adjust the experimental conditions according to the requirements of the sand swallowing experiment, and use the timing trigger controller 10 to control the sheet beam 7 and the high-resolution CCD camera under each experimental condition to capture and save the speckle images of the gravel. F. Concentration distribution measurement: Import the full-field speckle images of the inlet section of the aero-engine saved into the inlet sand and dust concentration measurement algorithm. The inlet sand and dust concentration measurement algorithm first segments the full-field speckle images, obtains the speckle images of each gravel and saves them independently; secondly, based on the gravel morphology and particle size inversion model, outputs the two-dimensional morphology of each gravel. S ; Then, the inlet sand and dust concentration measurement algorithm fits the two-dimensional morphology with a circle based on the basic geometric filling method S and calculates the equivalent particle size. D i Equivalent volume V i and equivalent mass m i ; Furthermore, a reference coordinate system is constructed with the center position of the aero-engine inlet as the reference, and the speckle images are meshed accordingly. The grid size is determined according to the maximum particle size D max in the test. The numerical values are mapped into the interval [0, 1] according to the number of gravels and the equivalent mass in each grid (0 means empty, 1 means all gravels), and then a statistical chart of the relative concentration of gravels is obtained.

[0034] Example 2 Referring to Figure 1 , the present invention proposes a device for measuring the sand and dust concentration distribution at the inlet of an aero-engine, including a short-pulse-width low-frequency laser 1 (corresponding to the pulsed laser light source in Example 1), an air-gap zero-order waveplate 2 (corresponding to the zero-order waveplate in Example 1), a 532 nm laser mirror 3 (corresponding to the mirror in Example 1), a 532 nm laser plano-convex cylindrical lens 4 (corresponding to the plano-convex cylindrical lens in Example 1), a 532 nm laser plano-concave cylindrical lens 5 (corresponding to the plano-concave cylindrical lens in Example 1), a distributed optical collector 9, a timing trigger controller 10, and a computer 11.

[0035] Referring to Figure 2 , during the calibration test, an ultrasonic standing wave force field is formed by an ultrasonic levitation table 6 composed of an upper part 16 and a lower part 17 of the ultrasonic levitation table. The irregular gravels 14 (corresponding to the multi-morphology gravels in Example 1) are levitated in the ultrasonic standing wave force field and irradiated by a sheet beam 7 and an illumination light source 15 respectively. The speckle images of the gravels generated by the sheet beam 7 are collected by a speckle image collector 12, and the morphology images of the gravels generated by the illumination light source 15 are collected by a gravel morphology collector 13. The speckle images and morphology images of the same irregular gravel 14 are stored in the computer 11 in one-to-one correspondence to obtain the mapping relationship between the gravel morphology and the speckle images.

[0036] Referring to Figure 3, the distributed optical collector 9 includes a pressure plate 24, a support 25, a support rod 26, a distributed fixing bracket 27, a telecentric camera lens 28, a horizontal rotation bracket 29, a vertical rotation bracket 30, a camera 31, etc. Specifically, the distributed optical collector 9 includes 4 telecentric camera lenses 28 and 4 cameras 31. The image stitching technology is adopted to realize the coupling of multiple cameras, so as to achieve the purpose of covering the intake air flow path of the aeroengine with the shooting area. The pressure plate 24, the support 25, the support rod 26, and the distributed fixing bracket 27 are used to fix the above-mentioned telecentric camera lenses 28 and cameras 31; the horizontal rotation bracket 29 and the vertical rotation bracket 30 are used to finely adjust the positions of the telecentric camera lenses 28 and cameras 31.

[0037] Refer to Figure 4 , the simulated harsh sand and dust environment 22 is generated by a sand and dust supply and dispersion device composed of a sand storage barrel 18, a sand delivery pipe 19, a sand fluidization section 20, and a sand dispersion pipe 21. Specifically, the sand in the sand storage barrel 18 falls to the sand fluidization section 20 under the action of gravity, and after being mixed and fluidized with high-pressure air in the sand fluidization section 20, it flows through the sand delivery pipe 19, and then is ejected at the sand dispersion pipe 21 to form a harsh sand and dust environment 22. Furthermore, the measurement principle of the present invention can be summarized as follows: the sheet-shaped light beam 7 is obtained by shaping the 532nm laser emitted by the short pulse-width and low-frequency laser 1 through optical elements such as an air-gap zero-order wave plate 2, a 532nm laser mirror 3, a 532nm laser plano-convex cylindrical lens 4, and a 532nm laser plano-concave cylindrical lens 5. The sheet-shaped light beam 7 is formed at the inlet 23 of the aeroengine. The sheet-shaped light beam 7 irradiates the irregular sand grains 14 in the harsh sand and dust environment 22. The irregular sand grains 14 emit sand grain coherent scattering light 8 to the surrounding space. The sand grain coherent scattering light 8 is collected by the distributed optical collector 9 fixed at the far field to obtain a laser speckle image. The speckle image is transmitted to the computer 11, and the built-in imported sand and dust concentration measurement algorithm is used to obtain the concentration data and concentration distribution of a local area in the harsh sand and dust environment 22.

[0038] Refer to Figure 5 , the implementation idea of the sand grain morphology and particle size inversion model is as follows: a. Based on the calibration test, a series of sand grain morphology images and the corresponding speckle images are obtained, a sand grain speckle image-morphology database is established, and the mapping relationship between the sand grain morphology and the speckle image is obtained according to the sand grain speckle image-morphology database; b. The sand grain morphology image is imported into the boundary recognition algorithm to read the morphology characteristics, and the morphology characteristics are used as the output and imported into the sand grain speckle simulation calculation model. The simulation calculation result is compared with the actually captured speckle image to verify the sand grain speckle simulation calculation model; c. Automatically generate a variety of images of abnormal-shaped gravel morphologies, i.e., the abnormal-shaped gravel morphology dataset, using the maximum inscribed rhombus method. Import this abnormal-shaped gravel morphology dataset into the gravel speckle simulation calculation model to obtain multiple groups of speckle images corresponding one-to-one to the gravel morphology images, i.e., the abnormal-shaped gravel speckle image dataset. Use the speckle images of this abnormal-shaped gravel speckle image dataset as the input and the gravel morphology images as the output, and train a gravel morphology and particle size inversion model using a deep learning network. The deep learning network specifically uses cGAN (Conditional Generative Adversarial Network).

[0039] Refer to Figure 6 , and the implementation idea of the imported sand and dust concentration measurement algorithm is as follows: Transmit the full-field speckle images collected in the sand swallowing test to the computer 11 and import them into the imported sand and dust concentration measurement algorithm. The imported sand and dust concentration measurement algorithm first performs segmentation on the full-field speckle images (i.e., initial image processing) to obtain the speckle images of each gravel and save them independently. Figure 6 In x 1 , y 1 ), ( x 2 , y 2 ), ( x 3 , y 3 ) and ( x 4 , y 4 ) are the coordinates of 4 gravels respectively; secondly, based on the gravel morphology and particle size inversion model, output the two-dimensional morphology of each gravel S ; then, the imported sand and dust concentration measurement algorithm fits the two-dimensional morphology S using a circle based on the basic geometric filling method and calculates the equivalent particle size D i ( D 1 , D 2 , D 3 and D 4 are the equivalent particle sizes of 4 gravels respectively), the equivalent volume V i and the equivalent mass m i ; furthermore, construct a reference coordinate system based on the center position of the aero-engine inlet and divide the speckle image into grids accordingly. According to the maximum particle size in the testD max Determine the grid size, map the values into the interval [0, 1] according to the number of sand and gravel in each grid and the equivalent mass (0 means empty, 1 means all sand and gravel), and then obtain the statistical chart of the relative concentration of sand and gravel. According to the statistical chart of the relative concentration of sand and gravel, the sand and dust concentration distribution at the inlet of the aero-engine can be obtained.

[0040] Specifically, for the method for measuring the sand and dust concentration distribution at the inlet of an aero-engine proposed by the present invention, taking the simulated harsh sand and dust environment 22 in the laboratory as an example, the device involved in the present invention is used to measure the sand and dust concentration distribution, including the following specific steps: (1) Static calibration: The speckle image collector 12 and the sand and gravel morphology collector 13 are installed in cooperation with a small vertical inclination angle. The optical axis of the speckle image collector 12 needs to be kept coincident with the central longitudinal axis of the intake air flow of the aero-engine, and with the optical axis of the speckle image collector 12 as the reference, the optical axis of the sand and gravel morphology collector 13 is inclined at an angle of about 1-2°, ensuring that the centers of the imaging screens of the speckle image collector 12 and the sand and gravel morphology collector 13 are aligned with the same spatial area. The ultrasonic suspension table 6 (composed of the upper part 16 and the lower part 17 of the ultrasonic suspension table) is installed in the imaging focal plane of the speckle image collector 12 and the sand and gravel morphology collector 13, and the force field center of the ultrasonic suspension table 6 is aligned with the center of the imaging area and the irradiation area of the sheet beam 7. The special-shaped sand and gravel 14 with different morphologies / sizes are placed at the force field center of the ultrasonic suspension table 6 in multiple times. Respectively using the sheet beam 7 and the illumination light source 15 (which cannot generate coherent scattered light) as the light source, the timing trigger controller 10 is used to control the short pulse width low-frequency laser 1, the speckle image collector 12 and the sand and gravel morphology collector 13 to act, so as to capture and save the sand and gravel speckle image and the high-resolution sand and gravel morphology image; (2) Construct a sand and gravel morphology and particle size inversion model: First, rely on the calibration device to obtain the sand and gravel morphology images of different sand and gravel and the corresponding speckle images, that is, the sand and gravel speckle-morphology database, and then obtain the mapping relationship between the sand and gravel morphology and the speckle image; Secondly, develop a sand and gravel speckle simulation calculation model based on the ray tracing method and the laser speckle imaging theory based on the mapping relationship between the sand and gravel morphology and the speckle image; Furthermore, use the maximum inscribed rhombus method to automatically generate a large number of sand and gravel morphology images, that is, the special-shaped sand and gravel morphology data set, and import it as the input into the sand and gravel speckle simulation calculation model. The sand and gravel speckle simulation calculation model will output the corresponding speckle image, and then a large number of speckle images corresponding to the sand and gravel morphology images can be obtained, that is, the special-shaped sand and gravel speckle image data set; Then, use the deep learning network to train the special-shaped sand and gravel speckle image data set to establish a sand and gravel morphology and particle size inversion model. The function of the sand and gravel morphology and particle size inversion model is to process the input speckle image and directly output the morphology and particle size information of the corresponding sand and gravel; (3)Testing and debugging: According to the requirement that the sheet beam 7 is perpendicular to the optical axis of the distributed optical collector 9, the short-pulse low-frequency laser 1, the shaping module (composed of an air-gap zero-order waveplate 2, a 532 nm laser mirror 3, a 532 nm laser plano-convex cylindrical lens 4, and a 532 nm laser plano-concave cylindrical lens 5), and the distributed optical collector 9 are arranged at appropriate positions in a separated manner. Specifically, the circular laser beam is emitted from the short-pulse low-frequency laser 1, its polarization angle is adjusted by the air-gap zero-order waveplate 2, and the 532 nm laser mirror 3 is used to adjust its emission direction to align with the beam shaping part. The beam shaping part is composed of a 532 nm laser plano-convex cylindrical lens 4 and a 532 nm laser plano-concave cylindrical lens 5, and its optical axis is in the horizontal and vertical orientation of the central longitudinal axis of the intake air flow of the aero-engine. By compressing the x direction and stretching the y direction of the laser beam, the output of the sheet beam 7 is realized, and its thickness is kept uniform within a region of 800 mm in length. Among them, the short-pulse low-frequency laser 1 and the shaping module should ensure that the optical path part is not less than 50 cm away from the intake air flow region of the aero-engine, and the distributed optical collector 9 in the optical image acquisition module is not less than 150 cm away from the inlet section of the aero-engine; (4)Simulating the harsh sand and dust environment 22: Install the sand and dust supply and dispersion device (composed of a gravel storage bucket 18, a gravel conveying pipe 19, a gravel fluidization section 20, a gravel dispersion pipe 21, etc.), connect the required gas pipeline and turn on the sand and dust supply and dispersion device, observe whether the sand and dust in the simulated harsh sand and dust environment 22 flow stably towards the inlet of the aero-engine along with the intake air flow, and adjust the adjustment knob of the sand and dust supply and dispersion device, observe whether the response of the sand and dust supply and dispersion device is normal and whether the particle size of the outflowing sand and dust changes. If everything is normal, maintain the operating state of the sand and dust supply and dispersion device; (5)Adjust the experimental conditions, and use the timing trigger controller 10 to control the sheet beam 7 and the distributed optical collector 9 under each experimental condition, capture and save the full-field speckle images of the inlet section of the aero-engine; (6)Concentration distribution measurement: Import the full-field speckle images of the inlet section of the aero-engine saved into the inlet sand and dust concentration measurement algorithm. The inlet sand and dust concentration measurement algorithm first segments the full-field speckle images, obtains the speckle images of each gravel and saves them independently; secondly, based on the gravel morphology and particle size inversion model, outputs the two-dimensional morphology of each gravel S ; then, the inlet sand and dust concentration measurement algorithm uses a circle to fit the two-dimensional morphology S based on the basic geometric filling method, and calculates and obtains the equivalent particle size D i , the equivalent volume V i , and the equivalent mass m i; Furthermore, a reference coordinate system is constructed based on the center position of the aviation engine inlet, and the speckle image is meshed accordingly. According to the maximum particle size in the experiment D max the grid size is determined, and the numerical values are mapped into the interval [0, 1] according to the number of sand grains and the equivalent mass in each grid (0 means empty, 1 means all sand grains), and then a statistical chart of the relative concentration of sand grains is obtained. According to the statistical chart of the relative concentration of sand grains, the sand and dust concentration distribution at the inlet of the aviation engine can be obtained.

[0041] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent replacements to the specific implementation manners of the invention, but these changes, modifications or equivalent replacements are all within the protection scope of the pending claims of the invention.

Claims

1. A device for measuring the concentration distribution of sand and dust at the inlet of an aircraft engine, characterized in that: Including pulse laser light source, shaping module, optical image acquisition module and data post-processing module: The pulse laser light source is placed at a preset position around the aircraft engine for emitting a laser beam, and the aircraft engine is located in a sand and dust environment to be tested; The shaping module is used to receive the laser beam and output a sheet-shaped beam (7); The optical image acquisition module is used to receive the coherent scattered light emitted by the gravel in the area irradiated by the sheet light beam (7), form a laser speckle image, and transmit the obtained laser speckle image to the data post-processing module; The data post-processing module processes the laser speckle image using an inlet dust concentration measurement algorithm to obtain the distribution of the inlet dust concentration of the aircraft engine.

2. The device for measuring the dust concentration distribution at the inlet of an aircraft engine according to claim 1, characterized in that: The optical image acquisition module comprises a distributed optical collector (9) and a timing trigger controller (10), wherein the timing trigger controller (10) is used to control the distributed optical collector (9) to capture coherent scattered light emitted by gravel to form a laser speckle image; The distributed optical collector (9) comprises a plurality of cameras (31) and a telephoto camera lens (28) cooperating with the cameras (31).

3. The device for measuring the dust concentration distribution at the inlet of an aircraft engine according to claim 2, characterized in that: The shaping module comprises a zero-order wave plate, a reflector, a plano-convex cylindrical mirror and a plano-concave cylindrical mirror which are arranged in sequence, and the shaping module is used to make the plane where the sheet-shaped light beam (7) is located perpendicular to the optical axis of the camera (31).

4. The device for measuring the dust concentration distribution at the inlet of an aircraft engine according to claim 1, characterized in that: The data post-processing module is a computer (11) with a built-in inlet dust concentration measurement algorithm. The inlet dust concentration measurement algorithm is specifically: The laser speckle image obtained in the actual scene is input into the pre-established gravel morphology and particle size inversion model to obtain the gravel morphology and particle size information; Based on the morphology and particle size information of gravel, basic geometric figures are used to model the gravel and calculate the equivalent mass; A reference coordinate system is constructed based on the center position of the aircraft engine inlet. The laser speckle image is gridded according to the reference coordinate system. The grid size is determined according to the maximum particle size of the gravel. The number of gravel in each grid and the equivalent mass are converted into a value between 0 and 1, and then a statistical graph of the relative concentration of gravel is obtained. Based on the statistical graph of the relative concentration of gravel, the distribution of sand and dust concentration at the aircraft engine inlet is obtained.

5. The device for measuring the dust concentration distribution at the inlet of an aircraft engine according to claim 4, characterized in that: The establishment process of the gravel morphology and particle size inversion model is specifically as follows: A sand and gravel speckle simulation calculation model is obtained based on the mapping relationship between the pre-acquired sand and gravel morphology and the laser speckle image; The maximum inscribed diamond method is used to automatically generate several gravel morphology images as a special-shaped gravel morphology dataset, and the special-shaped gravel morphology dataset is imported into the gravel speckle simulation calculation model as input, and several laser speckle images corresponding to the gravel morphology images are output to obtain a special-shaped gravel speckle image dataset; A deep learning network is used to train the special-shaped gravel speckle image dataset and establish a gravel morphology and particle size inversion model.

6. The device for measuring the dust concentration distribution at the inlet of an aircraft engine according to claim 5, characterized in that: The mapping relationship between the gravel morphology and the laser speckle image is obtained by a calibration device, the calibration device comprising an ultrasonic suspension platform (6), a speckle image collector (12) and a gravel morphology collector (13), the ultrasonic suspension platform being installed in the imaging focal plane of the speckle image collector (12) and the gravel morphology collector (13), and the force field center of the ultrasonic suspension platform being aligned with the center of the imaging area and the irradiation area of ​​the sheet light beam (7); The ultrasonic suspension platform comprises an ultrasonic suspension platform upper portion (16) and an ultrasonic suspension platform lower portion (17), and the space between the ultrasonic suspension platform upper portion (16) and the ultrasonic suspension platform lower portion (17) is used to suspend sand and gravel with various morphologies; The gravel morphology collector (13) and the speckle image collector (12) respectively collect the gravel morphology and the speckle image, and obtain a mapping relationship between the gravel morphology and the speckle image.

7. A method for measuring the concentration distribution of sand and dust at the inlet of an aircraft engine, based on the device for measuring the concentration distribution of sand and dust at the inlet of an aircraft engine according to claim 1, characterized in that: The method comprises the following steps: The laser beam is emitted by a pulsed laser light source placed at a preset position around the aircraft engine to be tested; The laser beam is received by the shaping module and outputs a sheet beam (7); Receiving coherent scattered light emitted by gravel in the area irradiated by the sheet light beam (7) through an optical image acquisition module to form a laser speckle image, and transmitting the obtained laser speckle image to a data post-processing module; The speckle image is processed by the data post-processing module to obtain the dust concentration distribution at the aircraft engine inlet.

8. The method for measuring the dust concentration distribution at the inlet of an aircraft engine according to claim 7, characterized in that: The laser speckle image is processed by the data post-processing module to obtain the dust concentration distribution at the aircraft engine inlet, specifically: The laser speckle image obtained in the actual scene is input into the pre-established gravel morphology and particle size inversion model to obtain the gravel morphology and particle size information; Based on the morphology and particle size information of gravel, basic geometric figures are used to model the gravel and calculate the equivalent mass; A reference coordinate system is constructed based on the center position of the aircraft engine inlet. The speckle image is gridded according to the reference coordinate system. The grid size is determined according to the maximum particle size of the gravel. The number of gravel in each grid and the equivalent mass are converted into a value between 0 and 1, and then a statistical graph of the relative concentration of gravel is obtained. Based on the statistical graph of the relative concentration of gravel, the distribution of sand and dust concentration at the aircraft engine inlet is obtained.

9. The method for measuring the dust concentration distribution at the inlet of an aircraft engine according to claim 8, characterized in that: The establishment process of the gravel morphology and particle size inversion model is specifically as follows: A sand and gravel speckle simulation calculation model is obtained based on the mapping relationship between the pre-acquired sand and gravel morphology and the laser speckle image; The maximum inscribed diamond method is used to automatically generate several gravel morphology images as a special-shaped gravel morphology dataset, and the special-shaped gravel morphology dataset is imported into the gravel speckle simulation calculation model as input, and several laser speckle images corresponding to the gravel morphology images are output to obtain a special-shaped gravel speckle image dataset; A deep learning network is used to train the special-shaped gravel speckle image dataset and establish a gravel morphology and particle size inversion model.

10. The method for measuring the dust concentration distribution at the inlet of an aircraft engine according to claim 9, characterized in that: The mapping relationship between the gravel morphology and the laser speckle image is obtained by a calibration device, the calibration device comprising an ultrasonic suspension platform (6), a speckle image collector (12) and a gravel morphology collector (13), the ultrasonic suspension platform (6) being installed in the imaging focal plane of the speckle image collector (12) and the gravel morphology collector (13), and the force field center of the ultrasonic suspension platform being aligned with the center of the imaging area and the irradiation area of ​​the sheet light beam (7); The ultrasonic suspension platform (6) comprises an ultrasonic suspension platform upper portion (16) and an ultrasonic suspension platform lower portion (17), and the space between the ultrasonic suspension platform upper portion (16) and the ultrasonic suspension platform lower portion (17) is used to suspend sand and gravel with various morphologies; The gravel morphology collector (13) and the speckle image collector (12) respectively collect the gravel morphology and the speckle image, and obtain a mapping relationship between the gravel morphology and the speckle image.

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