CN111707440B - Experimental device and method capable of obtaining continuous multi-amplitude microsecond-level time-dependent flow field - Google Patents
Experimental device and method capable of obtaining continuous multi-amplitude microsecond-level time-dependent flow field Download PDFInfo
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- CN111707440B CN111707440B CN202010547041.8A CN202010547041A CN111707440B CN 111707440 B CN111707440 B CN 111707440B CN 202010547041 A CN202010547041 A CN 202010547041A CN 111707440 B CN111707440 B CN 111707440B
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Abstract
The invention discloses an experimental device and method for obtaining continuous multi-microsecond-level time-dependent flow field, which comprises an experimental section for forming a flow field accompanied with trace particles by air flow, a multi-cavity laser for outputting laser pulses, a shooting device for shooting images of the flow field, a time synchronizer for setting triggering time sequences of the multi-cavity laser and a plurality of shooting units, a distortion calibration plate for correcting image distortion and a public identification area calibration plate for obtaining cross-correlation areas captured by different shooting units respectively. According to the invention, a plurality of shooting units are connected in parallel, a distortion calibration board is adopted to obtain a pixel coordinate correction function of image distortion when the shooting units shoot a flow field, and a public identification area calibration board is adopted to obtain cross-correlation areas and scaling translation functions of images shot by different shooting units; the inherent optical error of the experimental system in the shot flow field image is quantified and corrected through the combination of the two images, so that the accuracy of the method and the accuracy and effect of experimental measurement are improved.
Description
Technical Field
The invention relates to the technical field of optical flow display experiments, in particular to an experimental device and method for obtaining continuous multi-microsecond-level time-dependent flow fields.
Background
In order to promote the continuous progress of aerospace technology, a plurality of continuous microsecond-level time-related detailed flow field structures are helpful for revealing the whole process of development of various vortexes in a complex flow field, in particular to complex flow processes in the flow mechanics field such as supersonic speed turbulence boundary layers, shock wave strings, mixed layers and shock wave boundary layers which are mutually influenced.
The existing technologies mainly include two types: firstly, PIV shooting and NPLS shooting are carried out by using a double-cavity laser and a cross-frame camera, but the method has the defect that only two microsecond-level time-related detail flow field images of each group can be obtained, and the method is not suitable for observing the whole generation process of vortexes in the complex flow process and a flow field structure with strong unsteady characteristics; secondly, a high-speed camera is adopted for shooting, although a plurality of microsecond-level time-related fine flow field images can be obtained by adopting the mode, the dynamic characteristics of a flow field can be observed, but the method is limited in that the pixel resolution of the shot images is low (generally, only 320 × 320) on the premise that the technical level of the high-speed camera meets the time correlation at present, and the shot images are difficult to be used for scientific research.
Chinese patent CN110095246A discloses a shooting system and an experimental system for shooting flow field structures in wind tunnel experiments, wherein the shooting device comprises a plurality of frame-crossing cameras, the frame-crossing cameras and the dual-cavity laser are arranged in one-to-one correspondence, and the input end of each frame-crossing camera is provided with a filtering component for passing light with specific wavelength. In the technical scheme, auxiliary optical devices such as a filter component and the like are used for preventing overexposure of the second frame, the complexity of the system is greatly improved, the system is too dependent on a cross-frame camera, the replaceability and the economy are not strong, further, the system does not have the functions of image correction and matching, and the shot flow field image and the experimental system have inherent optical errors, so that the accuracy of the experimental system and the accuracy and the effect of experimental measurement are difficult to guarantee.
Therefore, it is necessary to design a new experimental apparatus and method for obtaining a plurality of microsecond time-dependent flow fields.
Disclosure of Invention
Aiming at the technical problem to be solved, the invention provides a flow field experimental device and a method for obtaining continuous multiple microsecond-level time-dependent fine throttle field images by matching a plurality of shooting unit arrays and adopting a means of combining image distortion calibration and public area image calibration.
In order to solve the technical problems, the invention is realized by the following technical scheme: an experimental device for obtaining a plurality of continuous microsecond-level time-dependent flow fields, comprising:
the experimental section is used for forming a flow field accompanied with trace particles by the flowing of the gas flow;
the multi-cavity laser is arranged above the experimental section and used for outputting laser pulses to the experimental section so as to illuminate a flow field in the experimental section and enable trace particles in the flow field to emit scattered light;
the shooting device comprises a plurality of shooting units which are arranged in front of an observation area of an experimental section and form an array group, and the plurality of shooting units are exposed and imaged by using the scattered light to shoot a flow field image in the experimental section;
the time synchronizer is respectively connected with the multi-cavity laser and the shooting device and is used for setting the trigger time sequence of each shooting unit in the multi-cavity laser and the shooting device;
the distortion calibration board is used for obtaining a pixel coordinate correction function f of image distortion when different shooting units in the shooting device shoot a flow field in advance before a wind tunnel experiment;
and the public identification area calibration board is used for obtaining the cross-correlation area and the scaling translation function g of the flow field image shot by different shooting units in the shooting device in advance before the wind tunnel experiment.
Furthermore, the shooting units in the shooting device are frame-spanning cameras or CCD cameras meeting preset shutter parameters and exposure requirements, wherein the number of the shooting units in the array is 2-9, each shooting unit is numbered in sequence through a label, the shutters of the shooting units are all global shutters, and the exposure time is 1-3 microseconds.
Further, the time synchronizer sets the time interval of the laser pulses output by the multi-cavity laser to be 0.6-5 microseconds.
Furthermore, the distortion calibration plate is provided with calibration images, wherein the calibration images are a circle with the diameter D and a plurality of squares which are located at the center of the circle and are arrayed in a 2 i-2 i mode, the side lengths of the squares are all a, i is the number, the circle is used for correcting radial deformation of the flow field image, and the squares are used for correcting gradient distortion and parallelism of the flow field image.
Furthermore, the line width range of the calibration image is 0.05 mm-0.15 mm, and the value range of i is an integer within 1-5.
Furthermore, the public identification area calibration plate is provided with calibration images, the calibration images are rectangles with side lengths and widths of d and a plurality of dots which are located inside the rectangles and are arrayed in a j-j mode, wherein j is the number.
Furthermore, the side length width d of the rectangle ranges from 5mm to 10mm, the diameter range of the dots ranges from 2 mm to 5mm, and the value range of j is an integer within 3-10.
Furthermore, the configuration of the experimental section is any one of an external flow field, a rectangular section flow field and a circular internal section flow field.
The invention also provides an experimental method for obtaining a continuous multi-microsecond-level time-related flow field, which comprises the following steps of:
s1, inserting the distortion calibration board into the experimental section, and simultaneously shooting a reference picture on the distortion calibration board by a plurality of shooting units in the shooting device to obtain a picture A; correcting the picture A according to the size values a and D of the distortion calibration plate to obtain a pixel coordinate correction function f of image distortion of each shooting unit;
s2, inserting the public identification area calibration plate into the experimental section, and simultaneously shooting a reference picture on the public identification area calibration plate by a plurality of shooting units in the shooting device to obtain a picture B; according to the relative positions of the boundary area of the public identification area calibration board and the circle center coordinates of the dots, and in combination with a pixel coordinate correction function f of image distortion, obtaining respective cross-correlation areas and scaling translation functions g of different shooting units in the shooting device;
s3, setting the trigger time sequence of the multi-cavity laser and a plurality of shooting units in the shooting device through a time synchronizer, wherein the shooting time of each shooting unit corresponds to the laser time step of the corresponding cavity in the multi-cavity laser one by one;
and S4, respectively correcting the flow field image shot by each shooting unit by combining the pixel coordinate correction function f of image distortion obtained by the distortion calibration board and the cross-correlation area and the scaling translation function g obtained by the public identification area calibration board, and obtaining a plurality of continuous detail flow field images with microsecond-level time correlation.
The invention also provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to realize the following steps:
s1, inserting the distortion calibration board into the experimental section, and simultaneously shooting a reference picture on the distortion calibration board by a plurality of shooting units in the shooting device to obtain a picture A; correcting the picture A according to the size values a and D of the distortion calibration plate to obtain a pixel coordinate correction function f of image distortion of each shooting unit;
s2, inserting the public identification area calibration plate into the experimental section, and simultaneously shooting a reference picture on the public identification area calibration plate by a plurality of shooting units in the shooting device to obtain a picture B; according to the relative positions of the boundary area of the public identification area calibration board and the circle center coordinates of the dots, and in combination with a pixel coordinate correction function f of image distortion, obtaining respective cross-correlation areas and scaling translation functions g of different shooting units in the shooting device;
s3, setting the trigger time sequence of the multi-cavity laser and a plurality of shooting units in the shooting device through a time synchronizer, wherein the shooting time of each shooting unit corresponds to the laser time step of the corresponding cavity in the multi-cavity laser one by one;
and S4, respectively correcting the flow field image shot by each shooting unit by combining the pixel coordinate correction function f of image distortion obtained by the distortion calibration board and the cross-correlation area and the scaling translation function g obtained by the public identification area calibration board, and obtaining a plurality of continuous detail flow field images with microsecond-level time correlation.
Compared with the prior art, the invention has the advantages that:
the method adopts a plurality of shooting unit arrays, and each shooting unit is exposed once in a corresponding cavity in a multi-cavity laser, so that the defects that a frame-crossing camera can only complete the shooting of two pictures each time and the exposure time of a second frame is uncontrollable are overcome, and the problem that the shooting resolution of a high-speed camera in a microsecond time interval is low is also overcome, the image acquired by each frame of the method can reach 1000 ten thousand pixel resolution, and the price of the shooting unit is cheap and the source channel is wide; by increasing the number of shooting units in the shooting device, the number of flow field images related to each group of experimental time can be increased, and the flow mechanism and the development process can be analyzed more favorably.
The method comprises the steps that a distortion calibration plate is adopted to correct image distortion caused by distances and angles between a flow field and a plurality of shooting unit positions in a shooting device in advance before a wind tunnel experiment, and a public identification area calibration plate is adopted to obtain cross-correlation areas captured by different shooting units in the shooting device in advance before the wind tunnel experiment; and the inherent optical error of the experimental system in the shot flow field image is quantified and corrected through the combination of the distortion calibration plate and the public identification area calibration plate, so that the accuracy of the device and the method disclosed by the invention and the precision and the effect of experimental measurement are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
The invention is further described below with reference to the accompanying drawings:
FIG. 1 is a general structure diagram of an experimental apparatus for obtaining a plurality of microsecond time-dependent flow fields;
FIG. 2 is a schematic diagram of the distortion calibration plate of the present invention;
FIG. 3 is a schematic structural view of a public identification area calibration plate according to the present invention;
FIG. 4 is an internal block diagram of the computer device of the present invention;
1. a multi-cavity laser; 2. a time synchronizer; 3. a photographing device; 4. a distortion calibration plate; 5. a public identification area calibration board; 6. an experimental section; 11. a light guide arm.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
Descriptions in this specification as relating to "first", "second", etc. are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to any indicated technical feature or quantity. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
Example one
Implementation area: a circular inner cross-section flow field; purpose of the experiment: and realizing the flow field shooting of a 2D plane.
The experimental device capable of obtaining continuous multi-microsecond time-related flow fields as shown in fig. 1 is suitable for performing optical experiments on fine turbulence and flow processes, and discloses a complex flow mechanism which is difficult to analyze by a conventional method, and mainly comprises an experimental section 6, a multi-cavity laser 1, a shooting device 3, a time synchronizer 2, a distortion calibration plate 4 and a common identification area calibration plate 5.
More specifically, the experimental section 6 is used for enabling the gas flow to form a flow field accompanied with tracer particles; the multi-cavity laser 1 is arranged above the experimental section 6 and used for outputting laser pulses to the experimental section 6 to illuminate a flow field in the experimental section 6 and enable trace particles in the flow field to emit scattered light, and a light guide arm 11 on the multi-cavity laser 1 can extend to a window of the experimental section 6 and be aligned with the window; the shooting device 3 comprises a plurality of shooting units which are arranged in front of an observation area of the experimental section 6 and form an array group, in the embodiment, the shooting units are arrayed into one group and used for shooting a flow field image in the experimental section 6 by utilizing scattered light exposure imaging; the time synchronizer 2 is respectively connected with the multi-cavity laser 1 and the shooting device 3 and is used for setting the trigger time sequence of a plurality of shooting units in the multi-cavity laser 1 and the shooting device 3; the distortion calibration plate 4 is used for obtaining a pixel coordinate correction function f of image distortion when a plurality of shooting units in the shooting device 3 shoot the flow field image in advance before a wind tunnel experiment; the public identification area calibration board 5 is used for obtaining, in advance, a cross-correlation area and a scaling translation function g when the flow field image is captured by a plurality of capturing units in the capturing device 3 before a wind tunnel experiment.
Preferably, the shooting unit in the shooting device 3 is a CCD camera meeting preset shutter parameters and exposure requirements, and other optical devices for assisting in shading and completing exposure, such as a filter assembly, are not required between each CCD camera and the flow field to be measured, thereby greatly reducing the complexity of the system. The number of CCD cameras in the array in this embodiment is 4 and is numbered 1, 2, 3, 4 in sequence by label. The shutters of the CCD cameras are all global shutters, and the exposure time is 1-3 microseconds; the time interval of the laser triggering of the adjacent cavity of the multi-cavity laser 1 is 0.6-5 microseconds. The multiple CCD camera arrays are adopted, and each CCD camera is exposed once in a corresponding cavity in the multi-cavity laser, so that the defects that a frame-crossing camera can only complete the shooting of two flow field images each time and the exposure time of a second frame is uncontrollable are overcome; by increasing the number of CCD cameras in the camera 3, the number of flow field images relevant to each set of experimental time can be increased, which is more advantageous for analyzing the flow mechanism and the development process.
In another embodiment of the present invention, the shooting units in the shooting device 3 are frame-crossing cameras, the number of the shooting units is 2 to 9, and each shooting unit is numbered sequentially through a tag, but the frame-crossing cameras are expensive and suitable for scenes with higher requirements.
In the present embodiment, as shown in fig. 2, the distortion calibration plate 4 has a calibration image, where the calibration image is a circle with a diameter D and a plurality of squares with a side length a and arranged in a 2 × 2 array at the center of the circle, the diameter D is a circular cross-sectional inner diameter, the circle is used to correct radial distortion of the flow field image, and the square is used to correct gradient distortion and parallelism of the flow field image; the line width of the calibration image should be as thin as possible, and the specific range is 0.05mm to 0.15mm, and more preferably 0.05mm, based on the recognition of the shooting unit.
In other embodiments of the invention, the squares are arrayed in a pattern of 4 x 4, 6 x 6, 8 x 8, 10 x 10 at the center of the circle.
In the present embodiment, as shown in fig. 3, the calibration plate 5 of the public identification area has a calibration image, which is a rectangle with a side length and a width d and a plurality of dots arranged in a 3 × 3 array inside the rectangle; the length, width and side length of the rectangle are selected according to an actual observation area of the flow field, the range of the side length and width d of the rectangle is 5-10 mm, and the diameter range of the dots is 2-5 mm.
In other embodiments of the invention, the dots are arranged in an array of 4 × 4, 5 × 5, 6 × 6, 7 × 7, 8 × 8, 9 × 9, 10 × 10 inside the rectangle.
As shown in fig. 2, since the coordinate and length relationship of the distortion calibration plate 4 are known, the difference between the actual flow field image and the distortion calibration plate 4 can be conveniently obtained by photographing the distortion calibration plate 4. Taking an experimental observation area as an internal flow field of a circular tube as an example, the circular tube is considered to have curvature deformation in the Y-axis direction, so that distortion in the Y-axis direction is generated, and the deformation in the X-axis direction can be ignored because no radian changes. The pixel coordinate point matrix of the reference picture is [ X1, Y1], and
after actual shooting, obtaining the coordinate point of the graph pixel as [ X1, Y2], and achieving the purpose of correcting distortion
By calculating f (X) from [ Y1] ═ Y2 × f (X1), f (X) can be defined as a polynomial expansion of degree 6, that is, by using a function fitting method
By solving the minimum variance of the equation, the constants alpha, beta, gamma, delta, epsilon,
η
similarly, if distortion exists in all relevant directions, the methods of the functions f1(X) and f2(Y) are similar to the examples.
As shown in fig. 3, each capturing unit first identifies the black frame in the image through gray value and image identification, and since the black frame is rectangular, the flow field image is deformed and corrected by using an image processing tool, and then the pixel coordinates of 9 dots in the image are solved, the image is translated by taking the pixel coordinate point of the central capturing unit as a reference, and the rest of the capturing units take the pixel coordinate point as a reference, wherein the function g1(X) of the pixel abscissa is μ X + ν, and the function of the pixel ordinate is a function of the pixel ordinate
Where μ is the scaling factor and v is the abscissaThe coordinate translation coefficient is a function of the coordinate translation,
the common area selection, scaling and translation of the cross-correlation area and the scaling translation function g and the picture distortion correction of the pixel coordinate correction function f subjected to image distortion are used as the ordinate translation coefficients, so that the photos taken by each shooting unit have spatial correlation, and the photos taken at a given time interval have temporal correlation.
Example two
The invention also provides an experimental method for obtaining a plurality of continuous microsecond-level time-related flow fields on the basis of the first embodiment, namely the using process of the first embodiment, which comprises the following steps:
s1, before the experiment begins, the distortion calibration plate 4 is inserted into the experiment section 6, and a plurality of shooting units in the shooting device 3 shoot a reference picture for the distortion calibration plate 4 at the same time to obtain a picture A; correcting the picture A according to the clear size values a and D in the distortion calibration plate 4 to obtain a pixel coordinate correction function f of image distortion of each shooting unit;
s2, before the experiment begins, the calibration board 5 of the public identification area is inserted into the experimental section 6, after a plurality of shooting units in the shooting device 3 shoot a reference picture for the distortion calibration board 4, a reference picture is shot for the calibration board 5 of the public identification area to obtain a picture B; according to the definite boundary area inside the public identification area calibration board 5 and the relative positions of the circle center coordinates of a plurality of dots, and in combination with a pixel coordinate correction function f of image distortion, obtaining the respective cross-correlation areas and scaling translation functions g of different shooting units in the shooting device 3;
s3, in a formal experiment, setting triggering time sequences of each shooting unit in the multi-cavity laser 1 and the shooting device 3 through the time synchronizer 2, wherein the shooting time of each shooting unit corresponds to the laser time step of a corresponding cavity in the multi-cavity laser 1 one by one, so that the shooting units are all sent 200-800 nanoseconds before the multi-cavity laser 1 is sent, the exposure time of the shooting units is 1-3 microseconds, and the laser triggering time interval of adjacent cavities is 0.6-5 microseconds;
and S4, after the shooting is finished, respectively correcting the flow field image shot by each shooting unit by combining the pixel coordinate correction function f of the image distortion obtained by the distortion calibration board 4 and the cross-correlation area and the zooming translation function g obtained by the public identification area calibration board 5, thereby obtaining a plurality of continuous microsecond-level time-dependent detail flow field images.
The invention provides a flow field experimental device and a method capable of obtaining continuous multi-microsecond time correlation, which adopts a distortion calibration plate to pre-correct image distortion caused by distances and angles between a flow field and a plurality of shooting unit positions in a shooting device before a wind tunnel experiment, and adopts a public identification area calibration plate to pre-obtain cross-correlation areas captured by different shooting units in the shooting device before the wind tunnel experiment; the inherent optical error of the experimental system in the shot flow field image is quantitatively corrected through the combination of the distortion calibration plate and the public identification area calibration plate, so that the accuracy of the device and the method and the precision and the effect of experimental measurement are improved; compared with a method adopting a high-speed camera, the method has the advantages of higher definition and more accurate precision through a plurality of shooting units and an image calibration method.
EXAMPLE III
Experiment area: an outflow flow field; purpose of the experiment: and realizing the flow field shooting of a 2D plane.
The experimental device for obtaining a continuous multi-microsecond time correlation flow field as shown in fig. 1 to 3 comprises an experimental section 6, a multi-cavity laser 1, a shooting device 3, a time synchronizer 2, a distortion calibration plate 4 and a public identification area calibration plate 5.
The difference from the first embodiment is that the diameter D of the distortion calibration plate 4 covers the whole experimental area of the external flow field to adapt to the experimental needs of the external flow field, and other parts and using processes are the same as those of the first embodiment.
Example four
Experiment area: a rectangular cross-section flow field; purpose of the experiment: 3D flow field shooting is realized.
The experimental device for obtaining a continuous multi-microsecond time correlation flow field as shown in fig. 1 to 3 comprises an experimental section 6, a multi-cavity laser 1, a shooting device 3, a time synchronizer 2, a distortion calibration plate 4 and a public identification area calibration plate 5.
The difference from the first embodiment is that the shooting unit arrays are 2-4 groups, angles between each shooting unit array group and a flow field observation area are different, distances are kept consistent as much as possible, the 2D plane flow field shooting and the 3D flow field shooting can be performed, and other parts and using processes are the same as those of the first embodiment.
EXAMPLE five
As shown in fig. 4, the present invention further provides a computer device according to the second embodiment, which includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method according to the second embodiment when executing the computer program.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. An experimental device for obtaining a plurality of continuous microsecond-level time-dependent flow fields, comprising:
the experimental section (6) is used for forming a flow field accompanied with tracer particles by the flowing of the gas flow;
a multi-cavity laser (1) for outputting laser pulses to the experimental section (6) to cause trace particles within a flow field to emit scattered light;
the shooting device (3) is used for shooting by utilizing the scattered light exposure imaging according to a plurality of shooting units of the array to obtain a flow field image in the experimental section (6);
a time synchronizer (2) for setting the trigger timing of the multi-cavity laser (1) and the plurality of shooting units in the shooting device (3);
the distortion calibration plate (4) is used for obtaining a pixel coordinate correction function of image distortion when the shooting unit shoots the flow field image in advance;
a public identification area calibration plate (5) for obtaining in advance a cross-correlation area and a scaling translation function when the shooting unit shoots the flow field image;
and respectively correcting the flow field image shot by each shooting unit by combining a pixel coordinate correction function of image distortion obtained by the distortion calibration board (4) and a cross-correlation area and a scaling translation function obtained by the public identification area calibration board (5), and obtaining a plurality of continuous detail flow field images with microsecond-level time correlation.
2. The experimental device for obtaining a continuous multi-microsecond time-dependent flow field according to claim 1, wherein the shooting unit is a frame-crossing camera or a CCD camera meeting preset shutter parameters and exposure requirements;
the number of the shooting units in the array is 2-9, each shooting unit is numbered in sequence through a label, the shutters of the shooting units are all global shutters, and the exposure time is 1-3 microseconds.
3. An experimental apparatus for flow field with time correlation in microseconds available continuously, according to claim 1, characterized in that the time synchronizer (2) sets the time interval of the laser pulses output from the multi-cavity laser (1) to 0.6-5 microseconds.
4. An experimental apparatus for obtaining a plurality of microsecond time-dependent flow fields according to claim 1, wherein the distortion calibration plate (4) has a calibration image, the calibration image is a circle with a diameter D and a plurality of squares with a side length a and arranged in an array of 2i x 2i at the center of the circle, wherein the circle is used for correcting the radial distortion of the flow field image, and the squares are used for correcting the gradient distortion and the parallelism of the flow field image.
5. The experimental apparatus for obtaining a plurality of microsecond time-dependent flow fields according to claim 4, wherein the line width of the calibration image is in the range of 0.05mm to 0.15mm, and the value of i is in the range of 1 to 5.
6. An experimental apparatus for flow field with time correlation in microseconds available continuously, according to claim 1, characterized in that said calibration plate (5) of public identification area has calibration image, said calibration image is rectangle with side length and width d and multiple dots arranged in j x j array in the interior of said rectangle.
7. The experimental device for obtaining a plurality of microsecond time-dependent flow fields as claimed in claim 6, wherein the side length width d of the rectangle is 5-10 mm, the diameter of the circular point is 2-5 mm, and the value of j is 3-10.
8. An experimental device for obtaining a plurality of microsecond time-dependent flow fields in succession according to claim 1, characterized in that the experimental section (6) is configured as any one of an external flow field, a rectangular section flow field and a circular internal section flow field.
9. A flow field experiment method for obtaining a plurality of microsecond time-dependent flow field experiment devices according to any one of claims 1-8, comprising the following steps:
s1, inserting the distortion calibration plate (4) into the experimental section (6), and simultaneously shooting a reference picture for the distortion calibration plate (4) by a plurality of shooting units in the shooting device (3) to obtain a picture A; correcting the picture A according to the size values a and D of the distortion calibration plate (4) to obtain a pixel coordinate correction function f of image distortion of each shooting unit;
s2, inserting the public identification area calibration plate (5) into the experimental section (6), and respectively shooting a reference picture for the public identification area calibration plate (5) by each shooting unit in the shooting device (3) to obtain a picture B; according to the relative positions of the boundary area of the public identification area calibration board (5) and the circle center coordinates of the dots, and in combination with a pixel coordinate correction function of image distortion, obtaining the respective cross-correlation areas and scaling translation functions g of different shooting units in the shooting device (3);
s3, setting triggering time sequences of a plurality of shooting units in the multi-cavity laser (1) and the shooting device (3) through the time synchronizer (2), wherein the shooting time of each shooting unit corresponds to the laser time steps of the corresponding cavity in the multi-cavity laser (1) one by one;
and S4, respectively correcting the flow field image shot by each shooting unit by combining the pixel coordinate correction function f of the image distortion obtained by the distortion calibration board (4) and the cross-correlation area and the scaling translation function g obtained by the public identification area calibration board (5), and obtaining a plurality of continuous detail flow field images with microsecond-level time correlation.
10. A computer arrangement comprising a memory and a processor, characterized in that the memory stores a computer program which, when executed by the processor, carries out the steps of the method as claimed in claim 9.
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| CN202010547041.8A CN111707440B (en) | 2020-06-16 | 2020-06-16 | Experimental device and method capable of obtaining continuous multi-amplitude microsecond-level time-dependent flow field |
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| CN112504627B (en) * | 2020-11-20 | 2023-08-15 | 中国船舶科学研究中心 | Simple calibration method for PIV of right-angle section cavitation water drum |
| CN113960043A (en) * | 2021-10-20 | 2022-01-21 | 中国人民解放军国防科技大学 | Method and device for determining time evolution characteristics of supersonic/hypersonic turbulence |
| CN115469115B (en) * | 2022-11-14 | 2023-01-31 | 中国空气动力研究与发展中心设备设计与测试技术研究所 | Fluorescence detection method and device |
| CN117647374B (en) * | 2024-01-25 | 2024-04-16 | 中国空气动力研究与发展中心高速空气动力研究所 | Method for obtaining migration speed of high-speed jet shear layer based on dynamic pressure data |
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