Three-dimensional background-oriented schlieren multi-camera experimental platform applied to jet flow measurement

Abstract

The application discloses a three-dimensional background-guided schlieren multi-camera experiment table applied to jet flow measurement, and belongs to the field of experimental testing devices.The three-dimensional background-guided schlieren multi-camera experiment table comprises a basic frame, a retractable camera mounting frame mounted on the basic frame, an adjustable background plate mounting frame mounted on the inner side of the camera mounting frame, a camera array in a semicircle distribution, and a jet flow experiment device; the jet flow experiment device is used for generating a jet flow to be measured; the jet flow experiment device is arranged near the center in the camera mounting frame, the position of the camera array is adjusted to be in a semicircle distribution along the jet flow to be measured through the retractable camera mounting frame, and the distance between the camera array and the jet flow experiment device is adjusted through the retracting and expanding range of the camera mounting frame; the background plate is adjusted to a position opposite to the camera array through the adjustable background plate mounting frame, and the distance between the background plate and the jet flow experiment device can be adjusted. The three-dimensional background-guided schlieren multi-camera experiment table solves the problem that the distance between the background plate and the jet flow to be measured and the distance between the camera and the jet flow to be measured are inconvenient to adjust.

Description

Technical Field

[0001] This invention belongs to the field of experimental testing devices, specifically relating to a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement. Background Technology

[0002] Background-guided schlieren imaging, as an experimental method for quantitatively measuring flow fields, has gradually gained attention from researchers due to its advantages such as non-contact operation, no particle intrusion, and ease of operation. The experimental setup for background-guided schlieren imaging includes a background plate, the flow field to be measured, a digital camera, and a computer. Its basic principle is similar to traditional schlieren imaging, utilizing the property that light is deflected when passing through a flow field with density perturbations to obtain flow field information. This also leads to a common drawback: the measured flow field information is the result of integration along the light path, which cannot reveal the fine structure inside complex flow fields. To overcome this drawback, researchers use a combination of multiple cameras and background plates to observe flow field information from multiple perspectives, and combine this with tomographic algorithms to quantitatively reconstruct the three-dimensional results of the flow field.

[0003] Background-guided schlieren experimental systems require careful consideration of two parameters: the distance l from the background plate to the flow field under test. b The distance l from the camera to the flow field being measured c Variations in these two parameters can have opposing effects on the sensitivity and spatial resolution of the measurement system, requiring a trade-off between them. Related studies do not provide universally applicable values; often, multiple trials are needed to determine l based on the specific flow field being measured. b and l c The size of l. For a two-dimensional background-guided schlieren experiment, changing l b and l c It is easy to implement, but for 3D background guided schlieren experiments, changing l b and l c The overall structure of the experimental setup needs to be considered. Currently, 3D background-guided schlieren multi-camera experimental setups used for jet measurement are typically not easily adjustable, and changes to the setup are difficult. b and l c The previous setup required rebuilding the test bench, increasing experimental costs and complicating operation. The background-guided schlieren imaging experimental setup needs strong stability to minimize the impact of test bench vibration on background point displacement. Simultaneously, due to the limitations imposed by the gas supply pipeline, the nozzle experimental setup is typically immobile. To facilitate other flow field visualization and measurement experiments on the jet, the 3D background-guided schlieren multi-camera experimental bench must be mobile. Based on these requirements, it is necessary to design a 3D background-guided schlieren multi-camera experimental bench for jet measurement. Summary of the Invention

[0004] The technical problem to be solved:

[0005] To overcome the shortcomings of existing technologies, this invention provides a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement. Through the structural characteristics of a retractable camera mounting frame, the distance from the camera array to the jet experimental device can be adjusted; the distance from the background plate to the jet experimental device can be adjusted through the position adjustment of the adjustable background plate. This solves the problem of the distance l between the background plate and the flow field to be measured in existing experimental stages. b The distance l from the camera to the flow field being measured c The problem of inconvenient adjustment was addressed by incorporating a fixed frame and a movable mechanism, which solved both vibration and mobility issues.

[0006] The technical solution of the present invention is: a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement, comprising a base frame, a retractable camera mounting frame detachably mounted on the base frame, an adjustable background plate mounting frame detachably mounted inside the camera mounting frame, a camera array distributed in a semi-circle, and a jet experimental device; the jet experimental device is used to generate the jet flow field to be measured.

[0007] The jet experiment device is located near the center within the camera mounting frame. The position of the camera array is adjusted to a semi-circular distribution along the flow field to be measured using the retractable camera mounting frame. The distance between the camera array and the jet experiment device is adjusted by adjusting the retraction range of the camera mounting frame. The background plate is adjusted to a position opposite to the camera array using the adjustable background plate mounting frame, and the distance between the background plate and the jet experiment device can also be adjusted.

[0008] A further technical solution of the present invention is: the camera mounting frame includes a distance adjustment component as the main body of the frame and a mounting component for mounting the camera array; the distance adjustment component and the base frame form an octagonal frame structure, and the cross-section is contracted and expanded by adjusting the connection position between each side, thereby adjusting the distance between the camera array mounted on it and the jet experimental device.

[0009] A further technical solution of the present invention is: the distance adjustment component includes 7 sets of outer frame units connected in sequence, with their two free ends detachably connected to the base frame, thus forming an octagonal cross-section frame; the camera array is respectively mounted on the outer frame unit on the upper part of the distance adjustment component along the circumferential direction through support members and connectors, and the shooting direction of the camera is adjustable.

[0010] A further technical solution of the present invention is as follows: the outer frame unit includes two parallel straight rods; the base frame is located below as the bottom edge of an octagon; wherein the two vertically arranged outer frame units are the two sides of the octagon, and the top outer corners of the four straight rods are beveled at 135°; there are a total of 10 straight rods, including the top edge parallel to the bottom edge, the two sets of outer frame units connecting the top edge and the two sides, and the two sets of outer frame units connecting the bottom edge and the two sides, all with beveled at 135° at both ends; and the interior corners of the octagon are all connected by 135° angle brackets, and the two vertically arranged outer frame units are connected to the base frame by 90° angle brackets;

[0011] The mounting assembly includes 16 short rods as supports, which are vertically fixed between two straight rods of the outer frame unit located above and to one side of the octagon, respectively, to mount 16 industrial cameras distributed along the semicircle of the flow field to be measured and to adjust the angle of the cameras relative to the center of the flow field.

[0012] A further technical solution of the present invention is as follows: the background plate mounting frame includes a mounting frame as the main body of the frame, and a support component for positioning the mounting frame; the mounting frame includes four sets of inner frame units connected in sequence, which are parallel to the bottom edge, side edge, and oblique edge connecting the two side edges and the bottom edge of the octagon, respectively, and are opposite to the four sides of the camera array, for mounting the background plate; the support component includes two sets of support frame units, which are respectively vertically mounted on the two inner frame units at the outer end, for detachably connecting the mounting frame to the camera mounting frame.

[0013] A further technical solution of the present invention is as follows: the inner frame unit and the support frame unit are both rectangular frames fixed by four straight rods. The four sets of inner frame units are connected by 45° angle brackets, and one end of the remaining inner frame units, except for the vertically set inner frame units, is beveled at 135°. The two inner frame units at the outer end are connected to the two support frame units by 90° angle brackets. The distance from the background plate to the flow field to be measured is adjusted by adjusting the connection position between each inner frame unit.

[0014] A further technical solution of the present invention is: the basic frame is a rectangular frame connected by 4 straight rods and 4 90° corner brackets, which is horizontally set at the bottom of the entire test bench.

[0015] A further technical solution of the present invention is: it also includes a fixed frame, the fixed frame comprising a left fixed frame and a right fixed frame symmetrically installed on both sides of the camera mounting frame; the left and right fixed frames are both three-dimensional frame tripods used to support the fixed camera mounting frame.

[0016] A further technical solution of the present invention is that the straight rods of the basic frame, the straight rods and short rods of the camera mounting frame, the straight rods of the background plate mounting frame, and the components of the fixing frame are all made of aluminum profiles.

[0017] A further technical solution of the present invention is: it also includes a moving device, which consists of 4 casters connected to the bottom of the base frame by 4 square aluminum profile adapter plates, so as to realize the overall movement and horizontal adjustment of the experimental platform.

[0018] Beneficial effects

[0019] The beneficial effects of this invention are as follows: The multi-camera experimental platform for jet measurement of this invention adopts a retractable structure for the camera mounting frame, which can shrink or expand the cross-section as needed to adjust the position of the camera array mounted on it. At the same time, the camera mounting frame is designed as an octagonal cross-section frame, which can accurately position the camera and ensure timely installation without affecting the shooting effect due to installation errors. The background plate mounting frame is adjustable, and its position relative to the camera mounting frame is adjustable. The installation positions between the internal frame units are also adjustable, which facilitates the determination of the background plate position.

[0020] This invention can realize the distance l from the background plate to the flow field to be measured. b The distance l from the camera to the flow field being measured c Adjustable, reducing measurement errors caused by vibration of the experimental platform due to jet flow, and allowing the entire experimental platform to move. The challenge of this invention lies in ensuring that the angle between each camera and the line connecting the camera to the flow field remains constant when adjusting the distance from the camera to the flow field; and ensuring that the distance from each background plate to the flow field centerline is equal when adjusting the distance from the background plate to the flow field. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement, which is an optional embodiment of the present invention.

[0022] Figure 2 This is a front view of a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement, which is optional according to an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the structure of a three-dimensional background-guided schlieren multi-camera experimental platform for jet measurement, which is optionally used in an embodiment of the present invention, after adjusting the distance between the camera and the flow field to be measured.

[0024] Figure 4 This is a schematic diagram of camera position adjustment for a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement, which is optional according to an embodiment of the present invention.

[0025] Figure 5 This is a side view of a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement, which is optional according to an embodiment of the present invention.

[0026] Figure 6 This is a top view of a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement, which is optional according to an embodiment of the present invention.

[0027] Figure 7 This is a partially enlarged view of the camera mounting frame of a three-dimensional background-guided schlieren multi-camera experimental platform for jet measurement, which is optional according to an embodiment of the present invention.

[0028] Figure 8 This is a partially enlarged view of a three-dimensional background-guided schlieren multi-camera experimental stage background plate mounting frame for jet measurement, which is optional according to an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached drawings: 1. Basic frame; 2. Distance adjustment component of camera mounting frame; 3. Mounting component of camera mounting frame; 4. Mounting frame of background plate mounting frame; 5. Supporting component of background plate mounting frame; 6. Fixed frame; 7. Moving device; 8. Jet flow experimental device; 9. Upper right section of distance adjustment component of camera mounting frame; 10. Right section of distance adjustment component of camera mounting frame; 11. 135° corner bracket; 12. Lower section of distance adjustment component of background plate mounting frame; 13. Right section of distance adjustment component of background plate mounting frame; 14. 45° corner bracket. Detailed Implementation

[0030] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Based on the fact that the flow field information obtained by existing technology is the result of integration along the optical path, which cannot reveal the fine structure inside complex flow fields, this invention provides a three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement. The stage includes a basic frame, a retractable camera mounting frame detachably mounted on the basic frame, an adjustable background plate mounting frame detachably mounted inside the camera mounting frame, a semi-circularly distributed camera array, and a jet experimental device. The jet experimental device is used to generate the jet flow field to be measured. The jet experimental device is positioned near the center within the camera mounting frame. The position of the camera array is adjusted to a semi-circular distribution along the flow field to be measured using the retractable camera mounting frame, and the distance between the camera array and the jet experimental device is adjusted by adjusting the retraction range of the camera mounting frame. The background plate is adjusted to a position opposite to the camera array using the adjustable background plate mounting frame, and the distance between the background plate and the jet experimental device can also be adjusted. The multi-camera experimental platform using the technical solution of this invention records the three-dimensional information of the jet flow field by arranging multiple cameras and multiple background plates, providing image data for three-dimensional background-guided schlieren technology, and realizing the adjustable distance between the background plate and the flow field to be measured and the distance between the camera and the flow field to be measured, while ensuring the stability and mobility of the experimental platform.

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0034] Reference Figure 1 As shown in the figure, this embodiment discloses a three-dimensional background-guided schlieren multi-camera experimental platform for jet measurement, comprising a base frame 1, a distance adjustment component 2 for the camera mounting frame, a mounting component 3 for the camera mounting frame, a distance adjustment component 4 for the background plate mounting frame, a support component 5 for the background plate mounting frame, a fixed frame 6, a moving device 7, and a jet experimental device 8. The frame as a whole adopts a detachable aluminum profile structure. The base frame forms the foundation of the entire experimental platform, with the moving device connected below and the camera mounting frame connected above. The background plate mounting frame is supported by the camera mounting frame, and together with the camera mounting frame, they form an octagonal structure. The fixed frame secures the entire platform with the help of the camera mounting frame. The jet experimental device generates the jet flow field to be measured.

[0035] Reference Figure 2As shown, the camera mounting frame includes a distance adjustment component 2 as the main body of the frame, and a mounting component 3 for mounting the camera array. The distance adjustment component 2 and the base frame 1 form an octagonal frame structure. By adjusting the connection positions between the sides, the cross-section can be contracted and expanded, thereby adjusting the distance between the camera array mounted on it and the jet experimental device 8. The distance adjustment component 2 includes 7 sets of outer frame units connected in sequence, with their two free ends detachably connected to the base frame 1, thus forming an octagonal cross-section frame. The camera array is mounted circumferentially on the outer frame units on the upper part of the distance adjustment component through supports and connectors, and the shooting direction of the camera is adjustable.

[0036] Specifically, the outer frame unit includes two parallel straight rods; the base frame, as the bottom edge of an octagon, is located below; the two vertically arranged outer frame units are the two sides of the octagon, and the top corners of the four straight rods are beveled at 135°; there are a total of 10 straight rods, including the top edge parallel to the bottom edge, the two sets of outer frame units connecting the top edge and the two sides, and the two sets of outer frame units connecting the bottom edge and the two sides, all with beveled at 135° at both ends; and the interior corners of the octagon are connected by 135° angle brackets, and the two vertically arranged outer frame units are connected to the base frame by 90° angle brackets; the mounting assembly includes 16 short rods as supports, which are vertically fixed between the two straight rods of the outer frame units located above and on one side of the octagon, respectively, for mounting 16 industrial cameras distributed along the semicircle of the flow field to be measured and adjusting the angle of the cameras relative to the center of the flow field.

[0037] Reference Figure 2 As shown, the background plate mounting frame includes a mounting frame 4 as the main body of the frame, and a support component 5 for positioning the mounting frame. The mounting frame 4 includes four sets of inner frame units connected sequentially, each parallel to the bottom edge, side edge, and oblique edge connecting the two side edges and the bottom edge of the octagon, and opposite to the four sides of the camera array, for mounting the background plate. The support component 5 includes two sets of support frame units, each vertically mounted on the two outer inner frame units, for detachably connecting the mounting frame 4 to the camera mounting frame. Both the inner frame units and the support frame units are rectangular frames fixed by four straight rods. The four sets of inner frame units are connected by 45° angle brackets, and one end of each inner frame unit except the vertically arranged inner frame unit is beveled at 135°. The two outer inner frame units are connected to the two support frame units by 90° angle brackets. The distance from the background plate to the flow field to be measured is adjusted by adjusting the connection positions between the inner frame units.

[0038] Specifically, the distance adjustment component 2 of the camera mounting frame has an upper right section 9 and a right section 10, which are connected by a 135° angle bracket 11. The distance adjustment component 4 of the background plate mounting frame has a lower section 12 and a right section 13, which are connected by a 45° angle bracket 14.

[0039] Specifically, the basic frame 1 forms the foundation of the entire experimental platform, consisting of a rectangular structure formed by four 90° corner brackets and four sections of aluminum profiles. The moving device 7 is connected to the bottom of the basic frame, and the camera mounting frame is connected to the top. The moving device 7 is connected to the bottom of the basic frame by four casters via four square aluminum profile adapter plates, enabling the overall movement and horizontal adjustment of the experimental platform.

[0040] Specifically, refer to Figure 5 and 6 As shown, the fixed frame 6 is symmetrical about the experimental platform body to the left and right, including front and rear fixed parts, left and right fixed parts and bottom connecting parts. The front and rear and left and right fixed parts consist of 8 aluminum profiles with 135° beveled ends, which are connected to the camera mounting frame and bottom connecting parts by 45° angle brackets respectively.

[0041] The three-dimensional background-guided schlieren multi-camera experimental stage applying the technical solution of this invention achieves the distance l from the background plate to the flow field under test through adjustable aluminum profile structures 2, 3, 4, and 5. b The distance l from the camera to the flow field being measured c These two distances are adjustable. The fixed frame 6 reduces the measurement error caused by the vibration of the experimental platform due to the jet, and the moving device 7 makes the entire experimental platform movable.

[0042] like Figure 2 As shown, the distance l from the background plate to the flow field under test is... b The distance l from the camera to the flow field to be measured c Effective length of a single segment of the background board mounting frame (x) b Effective length of a single segment of the camera mounting frame (x) cThe diagram illustrates the camera mounting frame, which consists of a distance adjustment assembly 2 and a mounting assembly 3. The distance adjustment assembly 2 comprises 14 aluminum profiles (front and back). The four vertical profiles have a 135° bevel at the top, the upper six profiles have 135° bevels at both ends, and are connected by 135° angle brackets. The lower four profiles also have 135° bevels at both ends and are connected to the base frame via 135° angle brackets, thus supporting the distance adjustment assembly. The mounting assembly 3 comprises 16 aluminum profiles, vertically fixed between the front and back of the distance adjustment assembly, used to mount 16 industrial cameras distributed along a semi-circle of the flow field to be measured. The background panel mounting frame consists of a distance adjustment assembly 4 and a support assembly 5. The distance adjustment assembly 4 comprises eight aluminum profiles (front and back). Except for the two vertical profiles, the remaining six profiles have a 135° bevel at one end and are connected by 45° angle brackets. The support assembly 5 includes horizontal supports, 45° supports, and internal vertical supports, used to support the background panel mounting.

[0043] In this embodiment, the jet flow experimental device consists of a gas source, an experimental pipeline, and an experimental nozzle. It can be any type of flow field generating device; this embodiment uses an axisymmetric nozzle jet flow experimental device as an example. The specific operation is as follows:

[0044] like Figure 3 As shown, the distance from the camera to the flow field under test is from... Figure 1 The maximum value is adjusted to a smaller value. The specific implementation steps are as follows:

[0045] 1) Remove the distance adjustment component 4 and support component 5 from the background board mounting frame.

[0046] 2) Based on the required distance l' from the camera to the flow field to be measured c Calculate the effective length x' of a single segment of the distance adjustment component 2 on the camera mounting frame. c :

[0047] x' c =2·l' c ·tan22.5°

[0048] 3) Move the right section of the distance adjustment component 2 of the camera mounting frame and its fixing device to the left, so that the distance from the right section to the center of the flow field to be measured is l'. c .

[0049] 4) Move the upper right section of the distance adjustment component 2 of the camera mounting frame downwards relative to the right section (x). c -x' c ) / 2.

[0050] 5) Move the upper section of the distance adjustment component 2 of the camera mounting frame to the lower right relative to the upper right section by x. c -x' c .

[0051] 6) Move the upper left section of the distance adjustment component 2 of the camera mounting frame to the right relative to the upper section by x. c -x' c .

[0052] 7) Move the left section of the distance adjustment component 2 of the camera mounting frame and its fixing device to the right by l. c -l' c +(x c -x' c ) / 2.

[0053] 8) To ensure that the angle between each camera and the line connecting them to the center of the flow field remains constant, taking the bottom right camera as an example, such as... Figure 4 As shown, the right segment of the distance adjustment component 2 relative to the camera mounting frame needs to be moved upwards (l) c -l' c )·tanα. For n cameras arranged along a semicircle, the angle between the line connecting an adjacent camera and the center of the flow field is θ = 180° / n, then:

[0054] α=(n / 4-1) / 2·θ

[0055] 9) The principle for adjusting the distance between the background plate and the flow field to be measured is the same as that for the camera. Adjust the distance l' between the background plate and the flow field to be measured according to the required distance. b Calculate the effective length x' of a single segment of the background panel mounting frame distance adjustment component 4. b :

[0056] x' b =2·l' b ·tan 22.5°

[0057] Then adjust in the order of left, lower left, lower, and right.

[0058] Reference Figure 7 As shown, the upper right segment 9 and right segment 10 of the distance adjustment component 2 of the camera mounting frame are connected by a 135° angle bracket 11, with both ends of 9 and 10 being beveled at 135°. The angle bracket 11 is removed, and the effective length x of a single segment of the distance adjustment component 2 of the camera mounting frame is adjusted. c To change the distance l from the camera to the flow field being measured c .

[0059] like Figure 8 As shown, the lower section 12 and right section 13 of the distance adjustment component 4 of the backdrop mounting frame are connected by a 45° angle bracket 14. Both ends of 12 and 13 are beveled at 135°. Disassemble the angle bracket 14 and adjust the effective length x of a single section of the backdrop mounting frame. b To change the distance l from the camera to the flow field being measured b .

[0060] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement, characterized in that: It includes a basic frame, a retractable camera mounting frame that can be detachably mounted on the basic frame, an adjustable background plate mounting frame that can be detachably mounted inside the camera mounting frame, a camera array that is distributed in a semi-circle, and a jet flow experimental device; the jet flow experimental device is used to generate the jet flow field to be measured. The jet experiment device is set near the center within the camera mounting frame. The position of the camera array is adjusted to be distributed in a semi-circle along the flow field to be measured by the retractable camera mounting frame, and the distance between the camera array and the jet experiment device is adjusted by adjusting the retraction range of the camera mounting frame. The background plate is adjusted to a position opposite to the camera array by the adjustable background plate mounting frame, and the distance between the background plate and the jet experiment device can be adjusted. The camera mounting frame includes a distance adjustment component as the main body of the frame and a mounting component for mounting the camera array. The distance adjustment component and the base frame form an octagonal frame structure. By adjusting the connection position between each side, the cross section is contracted and expanded, thereby adjusting the distance between the camera array mounted on it and the jet experimental device. The distance adjustment component includes 7 sets of outer frame units connected in sequence, with their two free ends detachably connected to the base frame, thus forming an octagonal cross-section frame; the camera array is mounted circumferentially on the outer frame unit on the upper part of the distance adjustment component through support members and connectors, and the shooting direction of the camera is adjustable. The outer frame unit includes two parallel straight rods; the base frame, as the bottom edge of an octagon, is located below; the two vertically arranged outer frame units are the two sides of the octagon, and the top corners of the four straight rods are beveled at 135°; there are a total of 10 straight rods, including the top edge parallel to the bottom edge, the two sets of outer frame units connecting the top edge and the two sides, and the two sets of outer frame units connecting the bottom edge and the two sides, all with 135° beveled ends; and the interior corners of the octagon are connected by 135° angle brackets, and the two vertically arranged outer frame units are connected to the base frame by 90° angle brackets; the mounting assembly includes 16 short rods as supports, which are vertically fixed between the two straight rods of the outer frame units located above and on one side of the octagon, respectively, for mounting 16 industrial cameras distributed along the semicircle of the flow field to be measured and adjusting the angle of the cameras relative to the center of the flow field; The background panel mounting frame includes a mounting frame as the main body of the frame, and a support component for positioning the mounting frame; the mounting frame includes four sets of inner frame units connected end to end in sequence, which are parallel to the bottom edge, side edge, and oblique edge connecting the two side edges and the bottom edge of the octagon, respectively, and are opposite to the four sides of the camera array, for mounting the background panel; the support component includes two sets of support frame units, which are vertically mounted on the two inner frame units at the outer end, for detachably connecting the mounting frame to the camera mounting frame.

2. The three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement according to claim 1, characterized in that: Both the inner frame unit and the support frame unit are rectangular frames fixed by four straight rods. The four sets of inner frame units are connected by 45° angle brackets, and one end of each inner frame unit except the vertically set inner frame unit is beveled at 135°. The two outer inner frame units are connected to the two support frame units by 90° angle brackets. The distance from the background plate to the flow field to be measured is adjusted by adjusting the connection position between each inner frame unit.

3. The three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement according to claim 1, characterized in that: The basic frame consists of four straight rods and four 90° angle brackets connected to form a rectangular frame, which is horizontally positioned at the bottom of the entire test bench.

4. The three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement according to claim 3, characterized in that: It also includes a fixed frame, which includes a left fixed frame and a right fixed frame symmetrically installed on both sides of the camera mounting frame; both the left and right fixed frames are three-dimensional frame tripods used to support the fixed camera mounting frame.

5. The three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement according to claim 4, characterized in that: The straight rods of the basic frame, the straight and short rods of the camera mounting frame, the straight rods of the background plate mounting frame, and the components of the fixing frame are all made of aluminum profiles.

6. The three-dimensional background-guided schlieren multi-camera experimental stage for jet measurement according to claim 5, characterized in that: It also includes a moving device, consisting of four casters connected to the bottom of the base frame via four square aluminum profile adapter plates, to enable the overall movement and horizontal adjustment of the experimental platform.

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