Three-dimensional stereoscopic particle image velocity measurement system

Abstract

The invention provides a three-dimensional stereoscopic particle image velocity measurement system. The three-dimensional stereoscopic particle image velocity measurement system comprises a light source assembly, a receiving camera, a special-shaped prism and a processing unit. The light source assembly is suitable for emitting sheet light to illuminate tracer particles in a flow field to be measured; a sensor of the receiving camera is configured into two parts which are respectively suitable for recording images of a first view field and a second view field in a to-be-measured flow field, the first view field and the second view field are inclined relative to a to-be-measured plane, the inclined directions are opposite to form an included angle, and the first view field and the second view field also have an overlapping region; the special-shaped prism is arranged between the to-be-measured flow field and the receiving camera, and is suitable for respectively guiding light rays of the first view field and the second view field to the receiving camera, and enabling the optical path lengths of the light rays of the first view field and the second view field to be equal; and the processing unit is suitable for receiving and storing the image from the receiving camera and processing the image to obtain velocity field data of the flow field to be measured.

Description

Technical Field

[0001] The present disclosure relates to the technical field of volumetric particle image velocimetry, and more specifically, to a three-dimensional volumetric particle image velocimetry system. Background Art

[0002] In traditional stereoscopic particle image velocity (SPIV) measurements, a pair of cameras are arranged to simultaneously capture tracer particles in the same flow field from different viewing angles. By comparing tracer particle images captured at different time points, correlation analysis can be performed to obtain the three-dimensional velocity components of the flow field. In order to measure the velocity component of the tracer particle perpendicular to the shooting plane, the two cameras' shooting angles for the same tracer particle must form an angle greater than a certain threshold. Therefore, it is impossible for both cameras to be perpendicular to the shooting plane at the same time. When the camera sensor is not parallel to the shooting plane, parallax problems will result. Applying a tilt-shift lens and following the Scheimpflug Principle, i.e. ensuring that the camera sensor plane, lens plane, and shooting plane intersect in a straight line, can effectively reduce this parallax.

[0003] In a single-camera binocular imaging system, the existing technology uses prisms and mirrors to change the optical path so that the camera's sensor is divided into two areas, each of which records a different field of view image. For SPIV applications, a certain angle is required between the two fields of view, which results in different inclination angles of the two fields of view to the shooting plane, resulting in a higher parallax. Since the two fields of view share the same sensor and tilt-shift lens, it is difficult to simultaneously satisfy Sham's law by adjusting the tilt-shift lens to eliminate the parallax between the two fields of view.

[0004] In order to solve this problem, there is an urgent need for a three-dimensional volumetric particle image velocimetry system that can eliminate the parallax between the two fields of view based on single-camera imaging to make the image clear and accurate. Summary of the invention

[0005] In view of this, the present disclosure provides a three-dimensional volumetric particle image velocimetry system, in which a special-shaped prism is arranged between the flow field to be measured and the receiving camera, which is suitable for guiding the light of two fields of view with an angle to the receiving camera and making the optical path lengths of the light of the two fields of view equal to eliminate parallax.

[0006] One aspect of the present disclosure provides a three-dimensional volumetric particle image velocimetry system, comprising: a light source assembly, adapted to emit sheet light to illuminate tracer particles in a flow field to be measured; a receiving camera, wherein the sensor of the receiving camera is configured into two parts, adapted to record images of a first field of view and a second field of view in the flow field to be measured, respectively, wherein the first field of view and the second field of view are inclined relative to a plane to be measured, and the inclination directions are opposite to form an angle, and the first field of view and the second field of view also have an overlapping area; a special-shaped prism, arranged between the flow field to be measured and the receiving camera, adapted to guide the light of the first field of view and the second field of view to the receiving camera, respectively, and to make the optical path lengths of the light of the first field of view and the second field of view equal; and a processing unit, adapted to receive and store the images from the receiving camera, and to process the images to obtain velocity field data of the flow field to be measured.

[0007] According to an embodiment of the present disclosure, the receiving camera is arranged on one side of the special-shaped prism and corresponds to the inclination direction of the first field of view, wherein the special-shaped prism includes: an incident surface, which is parallel to the plane to be measured and is suitable for receiving light from the first field of view and the second field of view; an exit surface, facing the receiving camera, and is suitable for emitting light from the first field of view and the second field of view to the receiving camera; a first reflecting surface, which is arranged on the propagation path of the light of the first field of view and is suitable for reflecting the light of the first field of view from the incident surface to the exit surface; a second reflecting surface, which is arranged on the propagation path of the light of the second field of view and is suitable for reflecting the light of the second field of view from the incident surface; and a third reflecting surface, which is arranged on the propagation path of the light of the second field of view reflected by the second reflecting surface and is suitable for reflecting the light of the second field of view to the exit surface; wherein the optical path lengths of the light of the first field of view and the light of the second field of view in the special-shaped prism are equal.

[0008] According to an embodiment of the present disclosure, the distance from the first reflection surface to the exit surface is smaller than the distance from the third reflection surface to the exit surface; the first reflection surface and the third reflection surface are connected by a connecting surface, and the extension direction of the connecting surface is orthogonal to the extension direction of the exit surface.

[0009] According to an embodiment of the present disclosure, a reflective film is disposed on the first reflective surface, the second reflective surface, and the third reflective surface.

[0010] According to an embodiment of the present disclosure, the light source assembly includes: a laser generator, adapted to generate columnar laser light; and a light sheet former, adapted to convert the columnar laser light into the light sheet light.

[0011] According to an embodiment of the present disclosure, a shift lens is also included, which is fixedly connected to the above-mentioned receiving camera and is suitable for making the focal planes of the above-mentioned first field of view and the above-mentioned second field of view intersect with the sensor plane of the above-mentioned receiving camera at the Sham line, so that the images of the above-mentioned first field of view and the above-mentioned second field of view obtained are clear.

[0012] According to an embodiment of the present disclosure, it also includes a fixing component, which is suitable for mounting the above-mentioned special-shaped prism and the above-mentioned shift lens on the reserved opening on the flow channel to be measured; wherein, the above-mentioned flow field to be measured is formed in the above-mentioned flow channel to be measured, the above-mentioned light sheet is irradiated to the above-mentioned flow field to be measured through the above-mentioned reserved opening, and the light of the above-mentioned first field of view and the above-mentioned second field of view enters the above-mentioned special-shaped prism through the above-mentioned reserved opening.

[0013] According to an embodiment of the present disclosure, the above-mentioned fixing component includes: a prism bracket, installed on the above-mentioned flow channel to be measured, suitable for fixing the above-mentioned special-shaped prism, and the above-mentioned prism bracket is configured to make the above-mentioned incident surface of the above-mentioned special-shaped prism cover part of the above-mentioned reserved opening to leave space for the above-mentioned sheet of light to enter; and a lens mounting ring, installed on the above-mentioned prism bracket, suitable for fixing the above-mentioned tilt-shift lens, and making the above-mentioned tilt-shift lens face the above-mentioned exit surface of the above-mentioned special-shaped prism.

[0014] According to an embodiment of the present disclosure, the fixing assembly further includes a window holder, which is suitable for installing a transparent window on the reserved opening and installing the prism bracket on the flow channel to be measured.

[0015] According to an embodiment of the present disclosure, it also includes a synchronizer, which is communicatively connected with the processing unit, the light source assembly and the receiving camera; wherein the processing unit is also suitable for generating an acquisition signal, and the synchronizer synchronously controls the receiving camera and the light source assembly to capture the image in response to the acquisition signal.

[0016] According to the embodiments of the present disclosure, the light sheet generated by the light source assembly can uniformly illuminate the tracer particles in the flow field to be measured, providing clear imaging conditions for the receiving camera, and using a special-shaped prism to effectively guide the light of the first field of view and the second field of view with opposite inclination directions to different sensor areas of the same receiving camera, while making the optical path lengths of the two fields of view equal, thereby eliminating parallax during the imaging process and improving image quality and measurement accuracy of velocity field data. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0018] Figure 1 A schematic diagram of a three-dimensional volumetric particle image velocimetry system according to an embodiment of the present disclosure is schematically shown.

[0019] Figure 2 The working principle diagram of the special-shaped prism according to the embodiment of the present disclosure is schematically shown.

[0020] Figure 3 The diagram schematically shows the arrangement of the fixing assembly on the flow channel to be tested according to an embodiment of the present disclosure.

[0021] In the drawings, the meanings of the reference numerals are as follows:

[0022] 1. Light source components;

[0023] 11. Pianguang;

[0024] 12. Laser generator;

[0025] 13. Sheet light source former;

[0026] 2. Flow field to be measured;

[0027] 21. First field of view;

[0028] 22. Second field of view;

[0029] 23. Plane to be measured;

[0030] 24. Overlapping area;

[0031] 21', first virtual image plane;

[0032] 22', second virtual image plane;

[0033] 3. Receive camera;

[0034] 4. Special-shaped prism;

[0035] 41. Incident surface;

[0036] 42. Exit surface;

[0037] 43. a first reflecting surface;

[0038] 44. A second reflecting surface;

[0039] 45. The third reflecting surface;

[0040] 46. ​​Connecting surface;

[0041] 5. Tilt-shift lens;

[0042] 6. Fix the components;

[0043] 61. Prism bracket;

[0044] 62. Lens mounting ring;

[0045] 63. Window retainer;

[0046] 64. Transparent window;

[0047] 7. Flow channel to be tested;

[0048] 8. Processing unit;

[0049] 9. Synchronizer. DETAILED DESCRIPTION

[0050] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0051] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "include", "comprising", etc. used herein indicate the existence of the features, steps, operations and / or mechanisms, but do not exclude the existence or addition of one or more other features, steps, operations or mechanisms.

[0052] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0053] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0054] Figure 1 A schematic diagram of a three-dimensional volumetric particle image velocimetry system according to an embodiment of the present disclosure is schematically shown.

[0055] The embodiment of the present disclosure provides a three-dimensional particle image velocimetry system, such as Figure 1As shown, it includes: a light source component 1, which is suitable for emitting a sheet of light 11 to illuminate the tracer particles in the flow field 2 to be measured; a receiving camera 3, the sensor of the receiving camera 3 is configured into two parts, which are respectively suitable for recording the images of the first field of view 21 and the second field of view 22 in the flow field 2 to be measured, the first field of view 21 and the second field of view 22 are inclined relative to the plane 23 to be measured, and the inclination directions are opposite to form an angle, and the first field of view 21 and the second field of view 22 also have an overlapping area 24; a special-shaped prism 4, which is arranged between the flow field 2 to be measured and the receiving camera 3, and is suitable for guiding the light of the first field of view 21 and the second field of view 22 to the receiving camera 3 respectively, and making the optical path lengths of the light of the first field of view 21 and the second field of view 22 equal; and a processing unit 8, which is suitable for receiving and storing images from the receiving camera 3, and processing the images to obtain velocity field data of the flow field 2 to be measured.

[0056] According to the above-mentioned setting mode, by configuring the light source assembly 1 to emit a sheet of light 11, the tracer particles in the flow field 2 to be measured are effectively illuminated, ensuring that the receiving camera 3 can capture a clear particle image. The sensor of the receiving camera 3 is divided into two parts, which respectively record the images of the first field of view 21 and the second field of view 22. The first field of view 21 and the second field of view 22 are inclined relative to the plane 23 to be measured and in opposite directions, forming a certain angle and overlapping to a certain extent, providing rich data for subsequent image processing. The special-shaped prism 4 guides the light of the first field of view 21 and the second field of view 22 to different sensor areas of the receiving camera 3, and ensures that the optical path length is equal, thereby eliminating parallax and improving the accuracy of the image and the measurement accuracy of the velocity field data. The processing unit 8 is responsible for receiving, storing and processing these images, and finally calculating the three-dimensional velocity field data of the flow field 2 to be measured.

[0057] In an illustrative embodiment, Figure 1 As shown, the light source assembly 1 includes: a laser generator 12 , which is suitable for generating columnar laser light; and a light sheet shaper 13 , which is suitable for converting the columnar laser light into a light sheet 11 .

[0058] According to the embodiment of the present disclosure, the laser generator 12 can be specifically selected as a Nd-YAG double-pulse laser generator 12, the single pulse energy of the laser is 200mj, the working wavelength is 532nm, and the maximum repetition frequency is 15Hz. The sheet light source former 13 can be specifically selected with a focal length of f=-20mm, corresponding to a divergence angle of 15°, and can be flexibly adjusted within a focal length range of 0.3 to 2.0 meters to adapt to flow fields of different thicknesses and characteristics.

[0059] According to an embodiment of the present disclosure, the receiving camera 3 can specifically use an Imager LX2M CCD camera, which has cross-frame progressive scanning technology, 12-bit grayscale display, a resolution of 1600×1200, a pixel physical size of 7.4μm×7.4μm, and a shooting frame rate of up to 35 frames / second.

[0060] Figure 2 The working principle diagram of the special-shaped prism 4 according to the embodiment of the present disclosure is schematically shown.

[0061] In an illustrative embodiment, Figure 2 As shown, the receiving camera 3 is arranged on one side of the special-shaped prism 4 and corresponds to the tilt direction of the first field of view 21, wherein the special-shaped prism 4 includes: an incident surface 41, which is parallel to the plane to be measured 23 and is suitable for receiving light from the first field of view 21 and the second field of view 22; an exit surface 42, which faces the receiving camera 3 and is suitable for emitting light from the first field of view 21 and the second field of view 22 to the receiving camera 3; a first reflection surface 43, which is arranged on the propagation path of the light from the first field of view 21 and is suitable for emitting light from the incident surface 41; The light of the first field of view 21 of the surface 41 is reflected to the exit surface 42; the second reflecting surface 44 is arranged on the propagation path of the light of the second field of view 22, and is suitable for reflecting the light of the second field of view 22 from the incident surface 41; and the third reflecting surface 45 is arranged on the propagation path of the light of the second field of view 22 reflected by the second reflecting surface 44, and is suitable for reflecting the light of the second field of view 22 to the exit surface 42; wherein, the optical path lengths of the light of the first field of view 21 and the second field of view 22 in the special-shaped prism 4 are equal.

[0062] According to the above-mentioned configuration, the incident surface 41 of the special-shaped prism 4 is parallel to the plane to be measured 23, ensuring that the light from the first field of view 21 and the second field of view 22 can be evenly received. The exit surface 42 faces the receiving camera 3, and through the ingenious configuration of the first reflection surface 43, the second reflection surface 44 and the third reflection surface 45, the light from the two fields of view, after being reflected inside the special-shaped prism 4, reaches the sensor of the receiving camera 3 with equal optical path length, thereby eliminating parallax and improving the matching accuracy of the image.

[0063] In detail, the incident surface 41 is parallel to the plane to be measured 23, and the first field of view 21 and the second field of view 22 have an angle and are inclined in opposite directions, that is, the incident surface 41 is perpendicular to the midline of the angle between the first field of view 21 and the second field of view 22, and the light of the first field of view 21 and the second field of view 22 enter the incident surface 41 at the same incident angle. Afterwards, the light of the first field of view 21 is reflected by the first reflection surface 43 and emitted from the exit surface 42, and the light of the second field of view 22 is reflected by the second reflection surface 44 and the third reflection surface 45 and emitted from the exit surface 42. Further, as Figure 2As shown, according to the law of reflection and refraction of light, the first virtual image plane 21' of the first field of view 21 and the second virtual image plane 22' of the second field of view 22 can be obtained. By setting the inclination angles and positions of the three reflecting surfaces according to the angles of the two fields of view, the distance and angle between the first virtual image plane 21' and the second virtual image plane 22' can be minimized, that is, the optical paths of the light rays of the first field of view 21 and the second field of view 21 are equal, and they are incident on the sensor of the receiving camera 3 at the same angle.

[0064] According to the embodiment of the present disclosure, the special-shaped prism 4 is made of K9 optical glass, the refractive index corresponding to the laser with a wavelength of 532nm is about 1.5168, and the transmittance can reach 90%.

[0065] Furthermore, considering the actual difficulty of processing the special-shaped prism 4, the special-shaped prism 4 can be divided into two parts, processed separately, and then glued together.

[0066] In an illustrative embodiment, reflective films are disposed on the first reflective surface 43 , the second reflective surface 44 and the third reflective surface 45 .

[0067] According to the above-mentioned configuration, the reflection efficiency and image quality of light are significantly improved by configuring the reflection film on the three reflection surfaces of the special-shaped prism 4. The presence of the reflection film ensures that the light loss is minimal during the reflection process, thereby enhancing the transmission intensity of the light, so that the receiving camera 3 can capture a clearer and brighter particle image.

[0068] In detail, the reflective film includes a metal reflective film such as an aluminum film, a silver film, and the like.

[0069] According to the embodiment of the present disclosure, the first reflection surface 43, the second reflection surface 44 and the third reflection surface 45 are coated with aluminum film, and the reflectivity of the laser beam with a wavelength of 532 nm can reach 95%.

[0070] In an illustrative embodiment, Figure 1 and Figure 2 As shown, it also includes a shift lens 5, which is fixedly connected to the receiving camera 3 and is suitable for making the focal planes of the first field of view 21 and the second field of view 22 intersect the sensor plane of the receiving camera 3 at the Sham line, so that the images of the first field of view 21 and the second field of view 22 obtained are clear.

[0071] In detail, under the action of the special-shaped prism 4, the two virtual image planes of the first field of view 21 and the second field of view 22 can be regarded as being in the same plane. At this time, through the single-receiving camera 3 and the shift lens 5, Schaum's law can be satisfied to obtain a high-quality particle image.

[0072] It should be noted that the Tilt-Shift Lens is a specially designed photographic lens that allows the photographer to adjust the optical axis of the lens when shooting, thereby changing the perspective relationship and clarity area of ​​the image. Sham's Law is an optical principle that states that when the focal plane of the lens, the film plane (or sensor plane) and the optical axis of the lens intersect in a straight line, the image on the entire focal plane will be clear. This straight line is called the Sham's line.

[0073] According to an embodiment of the present disclosure, the shift lens 5 is composed of a Nikon 50mm fixed-focus lens and a shift ring.

[0074] In an illustrative embodiment, Figure 2 As shown, the distance from the first reflecting surface 43 to the exit surface 42 is smaller than the distance from the third reflecting surface 45 to the exit surface 42 ; the first reflecting surface 43 and the third reflecting surface 45 are connected by a connecting surface 46 , and the extending direction of the connecting surface 46 is orthogonal to the extending direction of the exit surface 42 .

[0075] According to the above-mentioned setting mode, the boundary between the first reflection surface 43 and the third reflection surface 45 is connected by the connecting surface 46, and the connecting surface 46 is configured to be perpendicular to the exit surface 42, so that the first reflection surface 43 and the third reflection surface 45 are adjacent in the orthographic projection in the vertical direction of the exit surface 42, shortening the distance between the light in the reflection path of the first reflection surface 43 and the third reflection surface 45, reducing the angle difference between the first virtual image plane 21' and the second virtual image plane 22'. At the same time, it ensures that the reflection path of the first reflection surface 43 is not blocked, thereby improving the optical efficiency and image quality of the system.

[0076] Figure 3 The diagram schematically shows the arrangement of the fixing assembly 6 on the flow channel 7 to be tested according to an embodiment of the present disclosure.

[0077] In an illustrative embodiment, Figure 3 As shown, it also includes a fixing component 6, which is suitable for mounting the special-shaped prism 4 and the shift lens 5 on the reserved opening on the flow channel 7 to be measured; wherein, a flow field 2 to be measured is formed in the flow channel 7 to be measured, and the light sheet 11 is irradiated to the flow field 2 to be measured from the reserved opening, and the light of the first field of view 21 and the second field of view 22 enters the special-shaped prism 4 from the reserved opening.

[0078] According to the above-mentioned setting method, the fixing component 6 ensures the precise alignment and stable positioning of the special-shaped prism 4 and the shift lens 5, so that the sheet light 11 can accurately illuminate the flow field 2 to be measured through the reserved opening, and the light of the first field of view 21 and the second field of view 22 can smoothly enter the special-shaped prism 4 for optical processing. The integration and operational convenience of the entire three-dimensional stereoscopic particle image velocimetry system are improved, and the measurement error caused by equipment movement or vibration is reduced, thereby improving the stability and data quality of the flow field measurement. In addition, the use of the fixing component 6 also facilitates the rapid deployment and adjustment of the system, and is suitable for different experimental environments and flow channel structures.

[0079] According to the embodiments of the present disclosure, Figure 3 As shown, the fixing assembly 6 is mounted on the casing of the compressor, but the present disclosure is not limited thereto. In detail, the flow channel 7 to be tested includes, but is not limited to, the casing of the compressor, the blade channel of the turbine to study the flow characteristics of the blade surface, the wind tunnel test section to simulate the airflow around the aircraft, the water tunnel to simulate the fluid behavior of underwater objects, the inlet and outlet pipes of the pump to analyze the flow efficiency in the pump, the intake duct of the car to study the engine intake system, the application of pipeline flow analysis in the chemical industry and other industries, the microfluidic chip for biomedical and chemical analysis, the combustion chamber to explore the fuel combustion process, the cooling channel to analyze the heat exchange efficiency, and the local area of ​​the river or ocean to study the impact of water flow on the ecosystem.

[0080] In an illustrative embodiment, Figure 3 As shown, the fixing assembly 6 includes: a prism bracket 61, which is installed on the flow channel 7 to be measured and is suitable for fixing the special-shaped prism 4. The prism bracket 61 is constructed so that the incident surface 41 of the special-shaped prism 4 covers part of the reserved opening to leave space for the sheet light 11 to enter; and a lens mounting ring 62, which is installed on the prism bracket 61 and is suitable for fixing the shift lens 5 so that the shift lens 5 is directly opposite to the exit surface 42 of the special-shaped prism 4.

[0081] According to the above-mentioned setting mode, the fixing component 6 ensures the precise alignment and stable fixation of the special-shaped prism 4 and the shift lens 5, wherein the prism bracket 61 makes the incident surface 41 of the special-shaped prism 4 partially cover the reserved opening, providing a path for the sheet light 11 to enter the flow field 2 to be measured, while ensuring the efficiency of light entering the special-shaped prism 4. The lens mounting ring 62 ensures that the shift lens 5 is directly facing the exit surface 42 of the special-shaped prism 4, and only the position of the sheet light 11 and the inclination and focal length of the shift lens 5 need to be adjusted during measurement. The optical performance and measurement stability of the entire three-dimensional stereoscopic particle image velocimetry system are improved, the errors caused by equipment vibration or misalignment are reduced, and accurate three-dimensional flow field data are ensured.

[0082] In an illustrative embodiment, Figure 3As shown, the fixing assembly 6 further includes a window fixture 63, which is suitable for installing a transparent window 64 on the reserved opening and installing the prism bracket 61 on the flow channel 7 to be measured.

[0083] According to the above arrangement, a transparent window 64 can be installed on the reserved opening through the window holder 63, thereby protecting the internal optical elements, such as the special-shaped prism 4 and the shift lens 5, from direct contact and possible damage caused by the fluid in the flow channel, and also helping to maintain the sealing of the flow channel and the cleanliness of the optical path. At the same time, the window holder 63 can also be used to connect the flow channel 7 to be tested and the prism bracket 61.

[0084] In an illustrative embodiment, the window holder 63 may be mounted on the flow channel to be measured 7 by fastening bolts.

[0085] In an illustrative embodiment, the window holder 63 and the prism holder 61 may be processed by computer numerical control (CNC). Specifically, when designing the prism holder 61 , a groove may be provided according to the special-shaped prism 4 to fix the position of the special-shaped prism 4 .

[0086] In an illustrative embodiment, Figure 1 As shown, it also includes a synchronizer 9, which is communicatively connected with the processing unit 8, the light source assembly 1 and the receiving camera 3; wherein the processing unit 8 is also suitable for generating an acquisition signal, and the synchronizer 9 synchronously controls the receiving camera 3 and the light source assembly 1 to capture an image in response to the acquisition signal.

[0087] In detail, the processing unit 8 is used to set the shooting frequency of the receiving camera 3 and the laser pulse frequency of the laser generator 12, and transmit the data to the synchronizer 9 through the data line. The synchronizer 9 connects the receiving camera 3 and the laser generator 12 through a BNC line. The synchronizer 9 controls the synchronous shooting of the camera and the laser generator 12 to obtain the measurement image.

[0088] Furthermore, according to an embodiment of the present disclosure, the processing unit 8 may use image processing and analysis software to perform data acquisition and data pre-processing, and import the pre-processed data into numerical calculation software for data processing and flow field image drawing to obtain flow field data and images.

[0089] According to the embodiment of the present disclosure, a three-dimensional volumetric particle image velocimetry system is realized by using a camera and a special-shaped prism 4. The parallax of the virtual image corresponding to different viewing angles of the camera is reduced through reflection on the prism coating surface, which solves the high parallax problem of the two fields of view of the single-camera SPIV, reduces the number of cameras and synchronization accuracy required for the traditional SPIV, reduces the equipment requirements, and has a high engineering application value; the fixed component 6 fixes the position of each optical element, simplifies the measurement operation process, and saves measurement time. The three-dimensional volumetric particle image velocimetry system of the present invention can reduce the parallax of different fields of view of the single-camera SPIV, obtain high-quality particle images, reduce the number of cameras used, simplify the measurement process of SPIV, and has a strong practical application value.

[0090] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A three-dimensional particle image velocimetry system, characterized in that: include: A light source assembly (1) adapted to emit sheet light (11) to illuminate tracer particles in the flow field to be measured (2); A receiving camera (3), wherein a sensor of the receiving camera (3) is configured into two parts, respectively adapted to record images of a first field of view (21) and a second field of view (22) in the flow field to be measured (2), wherein the first field of view (21) and the second field of view (22) are inclined relative to the plane to be measured (23), and the inclination directions are opposite to form an angle, and the first field of view (21) and the second field of view (22) also have an overlapping area (24); a special-shaped prism (4), arranged between the flow field to be measured (2) and the receiving camera (3), and adapted to guide the light of the first field of view (21) and the light of the second field of view (22) to the receiving camera (3), respectively, and to make the optical path lengths of the light of the first field of view (21) and the light of the second field of view (22) equal; as well as A processing unit (8) is adapted to receive and store the image from the receiving camera (3), and to process the image to obtain velocity field data of the flow field (2) to be measured.

2. The three-dimensional particle image velocimetry system according to claim 1, characterized in that: The receiving camera (3) is arranged on one side of the special-shaped prism (4) and corresponds to the tilt direction of the first field of view (21), wherein the special-shaped prism (4) comprises: An incident surface (41) parallel to the plane to be measured (23), and adapted to receive light from the first field of view (21) and the second field of view (22); an emission surface (42), facing the receiving camera (3), and adapted to emit light from the first field of view (21) and the second field of view (22) to the receiving camera (3); A first reflection surface (43) is arranged on a propagation path of the light of the first field of view (21), and is adapted to reflect the light of the first field of view (21) from the incident surface (41) to the exit surface (42); a second reflecting surface (44), arranged on a propagation path of the light of the second field of view (22), and adapted to reflect the light of the second field of view (22) from the incident surface (41); and a third reflecting surface (45), arranged on a propagation path of the light of the second field of view (22) reflected by the second reflecting surface (44), and adapted to reflect the light of the second field of view (22) to the exit surface (42); The optical path lengths of the light rays of the first field of view (21) and the light rays of the second field of view (22) in the special-shaped prism (4) are equal.

3. The three-dimensional particle image velocimetry system according to claim 2, characterized in that: The distance from the first reflection surface (43) to the exit surface (42) is smaller than the distance from the third reflection surface (45) to the exit surface (42); The first reflecting surface (43) and the third reflecting surface (45) are connected via a connecting surface (46), and an extending direction of the connecting surface (46) is orthogonal to an extending direction of the exit surface (42).

4. The three-dimensional particle image velocimetry system according to claim 2, characterized in that: Reflective films are provided on the first reflective surface (43), the second reflective surface (44) and the third reflective surface (45).

5. The three-dimensional particle image velocimetry system according to claim 1, characterized in that: The light source assembly (1) comprises: A laser generator (12) adapted to generate a columnar laser; and The light sheet shaper (13) is suitable for converting the columnar laser into the light sheet (11).

6. The three-dimensional particle image velocimetry system according to claim 2, characterized in that: It also includes a shift lens (5) fixedly connected to the receiving camera (3) and adapted to make the focal planes of the first field of view (21) and the second field of view (22) intersect with the sensor plane of the receiving camera (3) at the Sham line, so that the images of the first field of view (21) and the second field of view (22) are clear.

7. The three-dimensional particle image velocimetry system according to claim 6, characterized in that: It also includes a fixing assembly (6) adapted to mount the special-shaped prism (4) and the tilt-shift lens (5) on a reserved opening on the flow channel (7) to be measured; The flow field (2) to be measured is formed in the flow channel (7) to be measured, the sheet of light (11) is irradiated to the flow field (2) to be measured through the reserved opening, and the light of the first field of view (21) and the second field of view (22) enters the special-shaped prism (4) through the reserved opening.

8. The three-dimensional particle image velocimetry system according to claim 7, characterized in that: The fixing component (6) comprises: a prism holder (61), mounted on the flow channel (7) to be measured, and adapted to fix the special-shaped prism (4); the prism holder (61) being configured so that the incident surface (41) of the special-shaped prism (4) covers a portion of the reserved opening, thereby leaving space for the sheet of light (11) to enter; and A lens mounting ring (62) is mounted on the prism bracket (61) and is suitable for fixing the tilt-shift lens (5) so that the tilt-shift lens (5) faces the emission surface (42) of the special-shaped prism (4).

9. The three-dimensional particle image velocimetry system according to claim 8, characterized in that: The fixing assembly (6) further comprises a window fixer (63) adapted to install a transparent window (64) on the reserved opening, and to install the prism bracket (61) on the flow channel (7) to be measured.

10. The three-dimensional particle image velocimetry system according to claim 1, characterized in that: It also includes a synchronizer (9), wherein the synchronizer (9) is communicatively connected with the processing unit (8), the light source assembly (1) and the receiving camera (3); The processing unit (8) is further adapted to generate an acquisition signal, and the synchronizer (9) synchronously controls the receiving camera (3) and the light source assembly (1) to capture the image in response to the acquisition signal.

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