An experimental device and method for exploring attack effect of underwater near-field explosion on small-size and small-mass target

Abstract

This invention belongs to the field of underwater explosion experimental technology, specifically relating to an experimental apparatus and method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets. The experimental apparatus provided by this invention demonstrates outstanding advantages in improving the scientific rigor and applicability of underwater near-field explosion experiments, and lays a solid foundation for in-depth research on the damage mechanisms of small-sized, low-mass targets. This invention adopts a modular and flexible design, enabling precise synchronous data acquisition, non-contact parameter extraction and intelligent nonlinear motion analysis, and adaptability to complex experimental scenarios. It provides a reliable experimental platform for studying the damage mechanisms of small targets and lays a technical foundation for the attack and defense testing of underwater unmanned systems.

Description

Technical Field

[0001] This invention belongs to the field of underwater explosion experimental technology, specifically relating to an experimental apparatus and method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets. Background Technology

[0002] Underwater unmanned systems are typical examples of small underwater targets, characterized by their small size and light weight. Therefore, under explosive loads, bubbles can envelop small-volume targets or cause small-mass targets to move. Current research indicates that the damage effects of the shock wave and bubbles generated by an explosion on targets differ significantly, depending on factors such as the target's size, mass, and shape. While techniques for measuring wall pressure on curved boundaries from underwater near-field explosions are relatively mature—for example, Chinese invention patent application CN202010557766.5 discloses a multi-angle electric spark bubble wall pressure load experimental device—existing explosion experimental devices primarily target larger targets, and research on small targets remains insufficient, resulting in a lack of effective data and theoretical support to understand the impact of explosions on these targets.

[0003] These targets exhibit unique response characteristics during explosions, further complicating the research. However, there is currently a lack of experimental setups capable of simulating these conditions in a laboratory. Therefore, developing an explosion testing apparatus capable of accommodating small-sized, low-mass targets is particularly necessary to provide more accurate experimental data for damage assessment and protection design. Summary of the Invention

[0004] The purpose of this invention is to provide an experimental apparatus and method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets.

[0005] An experimental apparatus for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets includes a trough plate, an experimental support, an experimental water tank, a high-voltage electrical control box, an electric spark base, a first experimental cylinder mounting mechanism, and a second experimental cylinder mounting mechanism.

[0006] The slotted plate has a positioning port and two slots, with the positioning port located between the two slots. The experimental water tank is installed inside the experimental support, and a crossbeam is installed on the top of the experimental support. A structural frame extending vertically is installed on the crossbeam. The electric spark base is installed inside the experimental water tank, and a discharge needle column is installed on the electric spark base. A discharge needle is installed at the upper end of the discharge needle column. Light sources and high-speed cameras are located on both sides of the experimental support. The high-speed camera is paired with a signal acquisition device to capture the contact process between the electric spark bubble and the experimental cylinder. The high-voltage control box is connected to the discharge needle through a wire and is connected to the high-speed camera and signal acquisition device through a synchronization sensor to ensure that the high-voltage control box, high-speed camera, and signal acquisition device work synchronously.

[0007] The first experimental cylinder mounting mechanism includes a first experimental cylinder and two sets of sliding positioning plates. The spacing between the two sets of sliding positioning plates is adapted to the first experimental cylinder, and the upper end of the first experimental cylinder is fixed to the lower end of the two sets of sliding positioning plates.

[0008] The second experimental cylinder mounting mechanism includes a second experimental cylinder and two sets of sliding plates, the spacing of which is adapted to the second experimental cylinder; each sliding plate includes an upper annular mounting opening and a lower slide rail; both ends of the second experimental cylinder are respectively disposed in the lower slide rails of the two side sliding plates.

[0009] An experimental method for investigating the effect of underwater near-field explosions on small-sized, low-mass targets includes the following steps:

[0010] Step 1: Design the first and second experimental cylinders based on the small size and small mass target;

[0011] The first experimental cylinder is a complete cylinder, and the second experimental cylinder has grooves at both ends. The first experimental cylinder and the second experimental cylinder have the same radius and mass.

[0012] Step 2: Arrange the slot plate vertically and install it at the lower end of the structural frame. After adjusting the spacing of the two sets of sliding positioning plates, fix the upper end of the first experimental cylinder to the lower end of the two sets of sliding positioning plates, and fix the upper end of the two sets of sliding positioning plates in the slot of the slot plate.

[0013] Step 3: Fill the experimental water tank with water. Adjust the longitudinal position of the electric spark base according to the experimental content so that the first experimental cylinder and the discharge needle are below the water surface and the distance between the first experimental cylinder and the discharge needle meets the experimental requirements. Adjust the light source and the high-speed camera so that the light intensity of the light source meets the experimental requirements and the shooting position of the light source and the high-speed camera is on the same horizontal line as the discharge needle.

[0014] Step 4: Begin the first experiment with the cylindrical object. Use the high-voltage control box to generate underwater bubbles from the underwater discharge needle. The high-speed camera and signal acquisition device work synchronously.

[0015] Step 5: Unload the first experimental cylinder, sliding positioning plates, and slotted plate; arrange the slotted plate horizontally and install it at the lower end of the structural frame. Fit the upper annular mounting openings of the two sets of sliding plates into the two slots of the slotted plate through the positioning sliders. After adjusting the distance between the two sets of sliding plates by sliding the positioning sliders, set the left and right ends of the second experimental cylinder in the lower slide rails of the two side sliding plates, and fix the two sets of positioning sliders in the positioning openings of the slotted plate.

[0016] Step 6: Adjust the water level in the experimental tank, the initial position and distance between the second experimental cylinder and the discharge needle, and the shooting positions of the light source and the high-speed camera, consistent with Step 3;

[0017] Step 7: Begin the experiment with the second experimental cylinder. The underwater discharge needle is made to generate the same underwater bubbles as in Step 4 by the high-voltage control box. The second experimental cylinder moves vertically along the lower slide rail of the two side slides due to the explosion of the bubbles. The high-speed camera and signal acquisition instrument work synchronously.

[0018] Step 8: Based on the video captured by the high-speed camera, process each frame, convert each frame image into a grayscale image, apply Gaussian blur to smooth the image, and then obtain the outlines of the bubble and the first and second experimental cylinders through edge detection and binary filling.

[0019] Features were extracted from each connected region of the bubble profile. Based on the image size and scale, the variation law of bubble pulsation velocity with distance parameter in the two experiments was obtained. Feature points were extracted from each connected region of the first and second experimental cylinders. The displacement of the second experimental cylinder was identified. The Hearst exponent of the displacement time series was calculated based on the rescaled range analysis method. The nonlinear motion law of the second experimental cylinder was obtained based on the Hearst exponent. The experiment on the attack effect of underwater near-field explosion on small-sized and small-mass targets was completed.

[0020] Furthermore, in step 2, the slotted plates are arranged vertically and fixed to the lower end of the structural frame by bolts at the four corners.

[0021] Furthermore, in step 2, the upper end of the sliding positioning piece is fixed to two slots on the slot plate by positioning bolts.

[0022] Furthermore, in step 2, the upper end of the first experimental cylinder is fixed to the lower end of the sliding positioning plate by eye screws.

[0023] Furthermore, in step 5, the slotted plates are arranged horizontally and fixed to the lower end of the structural frame by corner brackets at the four corners.

[0024] Furthermore, in step 5, mounting holes are provided on both sides of the upper part of the annular mounting port of the slide plate, and it is connected to the lower sides of the positioning slider by bolts.

[0025] Furthermore, in step 5, the two sets of positioning sliders are fixed in the positioning opening of the slot plate by locking bolts.

[0026] Furthermore, in step 8, features are extracted from each connected region of the bubble profile. After the bubble reaches its maximum radius, the moment when the fill degree is less than 0.3 is considered the moment the bubble bursts. The curves showing the changes in bubble radius and fill degree are plotted. The expansion rate is defined as a positive value and the contraction rate as a negative value. The curves showing the changes in bubble radius over time, bubble expansion rate over time, and bubble longitudinal position and longitudinal velocity over time are plotted to obtain the variation law of bubble pulsation velocity with distance parameter in the two experiments.

[0027] Furthermore, the calculation of the Hurst exponent of the displacement time series based on the rescaled range analysis method in step 8 is specifically as follows:

[0028] The mean of a time series is calculated using rescaled range analysis. The time series X = {X1, X2, ..., X...} N}, where N represents the length of the sequence, and X represents the time series of displacement, velocity, and acceleration. First, calculate the mean of the time series:

[0029]

[0030] Calculate the deviation sequence Y i for:

[0031]

[0032] Calculate the cumulative deviation sequence Z i :

[0033]

[0034] The range of a cumulative deviation series is defined as:

[0035] R(N) = max(Z1, Z2, ..., Z N )-min(Z1,Z2,…,Z N )

[0036] That is, calculate the difference between the maximum and minimum values ​​of the Z-sequence;

[0037] The standard deviation S(N) of the time series X is:

[0038]

[0039] According to the rescaled range analysis method, the relationship between the rescaled range R / S and the time scale N follows a power law:

[0040]

[0041] Taking the logarithm transforms both sides into a linear relationship:

[0042]

[0043] The slope H is obtained through linear regression, and this value is the Hearst exponent.

[0044] The beneficial effects of this invention are as follows:

[0045] The experimental device of this invention demonstrates outstanding advantages in improving the scientific rigor and applicability of underwater near-field explosion experiments, and lays a solid foundation for in-depth research on the damage mechanisms of small-sized, low-mass targets. Its modular and flexible design enables precise and synchronous data acquisition, non-contact parameter extraction, and intelligent nonlinear motion analysis, adapting to complex experimental scenarios. It provides a reliable experimental platform for the study of damage mechanisms of small targets and lays a technical foundation for the attack and defense testing of underwater unmanned systems. Attached Figure Description

[0046] Figure 1 This is a front view schematic diagram of the first experimental cylindrical mounting mechanism in this invention.

[0047] Figure 2 This is a schematic isometric side view of the first experimental cylindrical mounting mechanism in this invention.

[0048] Figure 3 This is a front view schematic diagram of the second experimental cylindrical mounting mechanism in this invention;

[0049] Figure 4 This is a schematic isometric side view of the second experimental cylindrical mounting mechanism in this invention.

[0050] Figure 5 This is a partial schematic diagram of the electric spark discharge needle in this invention.

[0051] Figure 6 This is a partial structural diagram of the assembly of the second experimental cylindrical mounting mechanism and the experimental water tank in this invention.

[0052] Figure 7 This is a schematic diagram of the overall structure of the experimental apparatus of the present invention.

[0053] Figure 8 This is a schematic diagram of the assembly of the slider and the positioning slider in this invention.

[0054] Figure 9 This is an exploded structural diagram of the second experimental cylindrical mounting mechanism in this invention.

[0055] Figure 10 This is a schematic diagram of the structure of the second experimental cylinder in this invention.

[0056] Figure 11 for Figure 10 A schematic diagram of the cross-section at point AA. Detailed Implementation

[0057] The present invention will now be further described with reference to the accompanying drawings.

[0058] like Figures 1 to 11 As shown, the present invention provides an experimental apparatus for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets, including a second experimental cylinder 1, a slide rail 2, a slot plate 3, a positioning slider 4, a corner bracket 5, a structural frame 6, a sliding positioning piece 7, an eye screw 8, a first experimental cylinder 9, a light source 10, an experimental support 11, an experimental water tank 12, a high-speed camera 13, a signal acquisition instrument 14, a high-voltage electrical control box 15, a crossbeam 16, an EDM base 17, a discharge needle column 18, a discharge needle 19, a positioning bolt 20, and a locking bolt 21.

[0059] The slot plate 3 has a positioning port 32 and two slots 31, with the positioning port 32 located between the two slots 31. The experimental water tank 12 is installed inside the experimental support 11. A crossbeam 16 is installed on the top of the experimental support 11, and a structural frame 6 extending vertically is provided on the crossbeam 16. The electric spark base 17 is installed inside the experimental water tank 12. A discharge needle column 18 is installed on the electric spark base 17, and a discharge needle 19 is installed at the upper end of the discharge needle column 18. A light source 10 and a high-speed camera 13 are provided on both sides of the experimental support 11. The high-speed camera 13 is paired with a signal acquisition device 14 to capture the process of the electric spark bubble contacting the experimental cylinder. The high-voltage control box 15 is connected to the discharge needle 19 through a wire, and is also connected to the high-speed camera 13 and the signal acquisition device 14 through a synchronization sensor to ensure that the high-voltage control box 15, the high-speed camera 13, and the signal acquisition device 14 work synchronously.

[0060] The first experimental cylinder mounting mechanism includes a first experimental cylinder 9 and two sets of sliding positioning plates 7. The spacing between the two sets of sliding positioning plates 7 is adapted to the first experimental cylinder 9, and the upper end of the first experimental cylinder 9 is fixed to the lower end of the two sets of sliding positioning plates 7.

[0061] The second experimental cylinder mounting mechanism includes a second experimental cylinder 1 and two sets of sliding plates. The spacing between the two sets of sliding plates is adapted to the second experimental cylinder 1. The sliding plates include an upper annular mounting port 71 and a lower slide rail 2. The two ends of the second experimental cylinder 1 are respectively set in the lower slide rail 2 of the two side sliding plates.

[0062] An experimental method for investigating the effect of underwater near-field explosions on small-sized, low-mass targets includes the following steps:

[0063] Step 1: Design the first experimental cylinder 9 and the second experimental cylinder 1 based on the target of small size and small mass;

[0064] The first experimental cylinder 9 is a complete cylinder, and the second experimental cylinder 1 has grooves at both ends. The first experimental cylinder 9 and the second experimental cylinder 1 have the same radius and mass.

[0065] Step 2: Arrange the slot plate 3 vertically and fix it to the lower end of the structural frame 6 with bolts at the four corners. After adjusting the spacing of the two sets of sliding positioning plates 7, fix the upper end of the sliding positioning plates 7 to the two slots 31 on the slot plate 3 respectively with positioning bolts 20. Fix the upper end of the first experimental cylinder 9 to the lower end of the sliding positioning plates 7 with eye screws 8.

[0066] Step 3: Fill the experimental water tank 12 with water. Adjust the longitudinal position of the electric spark base 17 according to the experimental requirements so that the first experimental cylinder 9 and the discharge needle 19 are below the water surface and the distance between the first experimental cylinder 9 and the discharge needle 19 meets the experimental requirements. Adjust the light source 10 and the high-speed camera 13 so that the light intensity of the light source 10 meets the experimental requirements and the shooting position of the light source 10 and the high-speed camera 13 is on the same horizontal line as the discharge needle 19.

[0067] Step 4: Begin the experiment with the first cylinder 9. Use the high-voltage control box 15 to generate underwater bubbles with the underwater discharge needle 19. The high-speed camera 13 and the signal acquisition instrument 14 work synchronously.

[0068] Step 5: Unload the first experimental cylinder 9, sliding positioning piece 7, and slot plate 3; arrange the slot plate 3 horizontally and fix it to the lower end of the structural frame 6 by the corner brackets 5 at the four corners; the upper annular mounting openings 71 of the two sets of sliding pieces are fitted into the two slots 31 of the slot plate 3 by the positioning sliders 4; the upper sides of the annular mounting openings 71 of the sliding pieces are provided with mounting holes and are connected to the lower sides of the positioning sliders 4 by bolts; after adjusting the distance between the two sets of sliding pieces by sliding the positioning sliders 4, set the left and right ends of the second experimental cylinder 1 in the lower slide rails 2 of the two side sliding pieces; fix the two sets of positioning sliders 4 in the positioning openings 32 of the slot plate 3 by locking bolts 21;

[0069] Step 6: Adjust the water level in the experimental water tank 12, the initial position and distance between the second experimental cylinder 1 and the discharge needle 19, and the shooting positions of the light source 10 and the high-speed camera 13, consistent with Step 3;

[0070] Step 7: Begin the experiment of the second experimental cylinder 1. The underwater discharge needle 19 is made to generate the same underwater bubbles as in step 4 by the high voltage control box 15. The second experimental cylinder 1 moves vertically along the lower slide rail 2 of the two side slide plates 4 due to the explosion of the bubbles. The high-speed camera 13 and the signal acquisition instrument 14 work synchronously.

[0071] Step 8: Based on the video captured by the high-speed camera 13, process each frame, convert each frame image into a grayscale image, apply Gaussian blur to smooth the image, and then obtain the outlines of the bubble and the first experimental cylinder 9 and the second experimental cylinder 1 through edge detection and binary filling.

[0072] Features were extracted from each connected region of the bubble profile. Based on the image size and scale, the variation law of bubble pulsation velocity with distance parameter in the two experiments was obtained. Feature points were extracted from each connected region of the first experimental cylinder 9 and the second experimental cylinder 1. The displacement of the second experimental cylinder 1 was identified. The Hearst exponent of the displacement time series was calculated based on the rescaled range analysis method. The nonlinear motion law of the second experimental cylinder 1 was obtained based on the Hearst exponent. The experiment on the attack effect of underwater near-field explosion on small-sized and small-mass targets was completed.

[0073] The mean of a time series is calculated using rescaled range analysis. The time series X = {X1, X2, ..., X...} N}, where N represents the length of the sequence, and X represents the time series of displacement, velocity, and acceleration. First, calculate the mean of the time series:

[0074]

[0075] Calculate the deviation sequence Y i for:

[0076]

[0077] Calculate the cumulative deviation sequence Z i :

[0078]

[0079] The range of a cumulative deviation series is defined as:

[0080] R(N) = max(Z1, Z2, ..., Z N )-min(Z1,Z2,…,Z N )

[0081] That is, calculate the difference between the maximum and minimum values ​​of the Z-sequence;

[0082] The standard deviation S(N) of the time series X is:

[0083]

[0084] According to the rescaled range analysis method, the relationship between the rescaled range R / S and the time scale N follows a power law:

[0085]

[0086] Taking the logarithm transforms both sides into a linear relationship:

[0087]

[0088] The slope H is obtained through linear regression, and this value is the Hearst exponent.

[0089] Existing experimental cylinder fixing mechanisms can only limit the movement of experimental cylinders of a specific size, and the constraint method for experimental cylinders is singular, which cannot meet the needs of exploring the attack effect of explosions on small-sized, low-mass targets.

[0090] When an underwater unmanned system is attacked from directly below by an anti-underwater unmanned system, it will move, with the most significant movement occurring perpendicular to the horizontal plane, i.e., in the Z-direction. If the attack intensity is high, it may even damage the underwater unmanned system. The attack process can be simulated in experimental tank 12, where the underwater unmanned system can be simplified as a cylinder.

[0091] The experimental cylinder has two structures, corresponding to two experimental constraints.

[0092] The first constraint condition is that when conducting the experiment with the first experimental cylinder 9 as the target, the first experimental cylinder 9 has no degrees of freedom, and the first experimental cylinder fixing mechanism is used. Figure 1 The structural frame 6 is bolted to the crossbeam 16. The slotted plate 3 is bolted to the lowest side of the structural frame 6, meaning the slotted plate 3 is perpendicular to the ground. The upper parts of the two sliding positioning plates 7 have two through holes. Positioning bolts 20 pass through the through holes in the sliding positioning plates 7 and the corresponding slots 31 in the slotted plate 3, connecting to positioning nuts. The positioning bolts 20 fix the sliding positioning plates 7 to the slotted plate 3. Eye bolts 8 are bolted to the lower end of the sliding positioning plates 7. The self-tapping thread of the eye bolts 8 mates with the pre-drilled blind hole thread on the surface of the first experimental cylinder 9. By changing the position of the positioning bolts mate between the sliding positioning plates 7 and the slotted plate 3, the distance between the two sliding positioning plates 7 can be adjusted to accommodate first experimental cylinders 9 of different lengths.

[0093] The second constraint condition is that when conducting experiments with a second experimental cylinder 1 with positioning grooves at both ends as the target, the second experimental cylinder 1 with positioning grooves at both ends is fixed in the X and Y directions and free to move in the Z direction. That is, the second experimental cylinder with positioning grooves at both ends can only move perpendicular to the ground. Using the second experimental cylinder fixing mechanism, the structural frame 6 is bolted to the mounting beam 16, and the slot plate 3 is connected to the structural frame 6 by bolts and angle brackets 5. The slot plate 3 is located directly below the structural frame 6 and is parallel to the ground. Two positioning sliders 4 are installed in the corresponding slots of the slot plate. There is a through hole at the central axis of symmetry of the upper end face of the positioning slider 4. The locking bolt 21 passes through the through hole and is connected to the locking nut through the positioning port 32 on the center line of the slot plate 3. By loosening the locking bolt 21 on the upper end face of the positioning slider, the distance between the positioning sliders 4 can be adjusted to accommodate second experimental cylinders of different lengths. In the Z-direction free experiment, the second experimental cylinder 1 with positioning grooves at both ends is fitted with the slide rail 2 with a clearance, and is circumferentially and axially limited with the slide rail 2, ensuring that the second experimental cylinder 1 with positioning grooves at both ends only moves in the Z-direction after being subjected to bubble pulsation load.

[0094] When an underwater near-field electric spark explosion load is applied to the surface of the experimental cylinder, the cylinder will exhibit a corresponding response, including motion and damage. By adjusting the installation position of the electric spark base 17, a certain relative positional relationship can be maintained between the discharge needle 19 and the experimental cylinder. The discharge needle 19 is mounted on the discharge needle post 18, the discharge needle post 18 is mounted on the electric spark base 17, and the electric spark base 17 is mounted on the crossbeam 16. The discharge needle 19, the discharge needle post 18, and the electric spark base 17 are all submerged below the water surface in the experimental water tank 12. The position of the experimental cylinder in the experimental water tank 12 can be adjusted by the position of the structural frame 6 on the mounting crossbeam 16.

[0095] The high-voltage control box 15 is connected to the discharge needle 19 via a wire. At the same time, the high-voltage control box 15 is connected to the high-speed camera 13 and the signal acquisition device 14 via a synchronization sensor. The purpose is to ensure that the high-voltage control box 15, the high-speed camera 13, and the data acquisition device work synchronously. Because the time from the generation to the collapse of the underwater explosion bubble is very short (milliseconds), all devices need to work at the same time to avoid missing relevant data and phenomena due to the short time of the experimental phenomenon, especially the process from the beginning of contact between the electric spark bubble and the experimental cylinder until its collapse.

[0096] The experimental environment for this invention is as follows: Figures 5 to 7 As shown, the experimental water tank 12 is made of transparent glass, ensuring that the light emitted by the light source 10 can pass through the water tank. Simultaneously, the high-speed camera 13 captures the movement of objects inside the water tank. During the experiment, the water tank is placed on an experimental support and fixed in place. The light source and high-speed camera are placed on opposite sides of the water tank. The light source is 0.5 meters from the wall of the water tank. The high-speed camera is also 0.5 meters from the wall of the water tank. The center of the light source is at the same height as the high-speed camera. The experimental table is placed approximately 2 meters away from the water tank. The data acquisition instrument and high-voltage control box are placed on the experimental table.

[0097] The experimental support 11 is made of aluminum profiles, which are connected by bolts and angle brackets. The experimental support 11 is 1.5m high and 0.78m wide. The overall frame of the support is composed of 4 aluminum profiles of 1.5m and 8 aluminum profiles of 0.7m. The water tank platform is made of 7 aluminum profiles of 0.7m length spliced ​​together and installed in the lower part of the overall structure of the experimental support. The upper platform is 0.5m above the ground.

[0098] During the experiment, the experimental water tank 12 is installed and fixed on the water tank platform of the experimental support 11; the experimental water tank 12 is adjusted to be in the center position; the crossbeam 16 is fixed on the experimental support 11; the structural frame 6 is fixed to the crossbeam 16 with bolts; the height of the structural frame 6 is adjusted so that the experimental cylindrical body is in the center position below the horizontal plane inside the experimental water tank 12; the distance between the discharge needle 19 and the two experimental cylinders is adjusted; the discharge needle 19 discharges to generate an electric spark, which in turn causes the discharge needle 19 to generate bubbles in the experimental water tank 12. The bubbles couple with the first experimental cylinder 9 or the second experimental cylinder 1 and interact with each other. Under the interaction, the second experimental cylinder 1 moves in the Z direction, while the first experimental cylinder 9 does not move; at the same time, the bubbles pulsate and collapse; the high-speed camera 13 records the entire experimental process, and the signal acquisition instrument 14 stores the video file of the experimental process.

[0099] High-speed camera 13, combined with signal acquisition device 14, captures the contact process between electric spark bubble and experimental cylinder, simulating the attack process of anti-underwater unmanned system, providing an experimental basis for analyzing the near-field bubble pulsation and load characteristics of cylindrical surface boundary under different angles of attack and different explosion distances.

[0100] Based on the footage captured by the high-speed camera 13, a secondary programming image processing program was developed to read the video frame by frame and convert it into a grayscale image. Gaussian blur was applied to smooth the image, and then edge detection and binary filling were used to obtain the outlines of bubbles and small-sized, low-mass targets.

[0101] Features such as maximum diameter (radius) and fill degree are extracted from each connected region of the bubble. After the bubble reaches its maximum radius, the bubble bursts when the fill degree is below 0.3. The curves of the bubble radius and fill degree change are plotted. The bursting time (in milliseconds) is output to the console. Based on the bubble radius change rate, the expansion rate is positive and the contraction rate is negative, resulting in the following curves: bubble radius change over time, bubble expansion rate change over time, and bubble longitudinal position and longitudinal velocity change over time. The bubble motion pattern and bubble load are automatically identified to achieve non-contact measurement of the bubble parameters, and the variation law of the first and second pulsating bubble load with distance parameters is identified.

[0102] Feature points are extracted from each connected region of small-sized, low-mass targets, the motion patterns of small-sized, low-mass targets are automatically identified, and the motion parameters (including displacement, velocity, acceleration, etc.) of small-sized, low-mass targets are automatically output.

[0103] The experimental device of this invention has a simple structure, is suitable for small size and small mass targets, has interchangeable parts, is easy to disassemble and assemble, is simple to operate, and can easily carry out multiple repeated experiments.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An experimental apparatus for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets, characterized in that: It includes a trough plate (3), an experimental support (11), an experimental water tank (12), a high-voltage electrical control box (15), an electric spark base (17), a first experimental cylinder mounting mechanism, and a second experimental cylinder mounting mechanism; The slot plate (3) has a positioning port (32) and two slots (31), with the positioning port (32) located between the two slots (31); the experimental water tank (12) is installed inside the experimental support (11), and a crossbeam (16) is installed on the top of the experimental support (11), with a structural frame (6) extending vertically on the crossbeam (16); the electric spark base (17) is installed inside the experimental water tank (12), and a discharge needle column (18) is installed on the electric spark base (17), with a discharge needle column (18) installed on the upper end of the discharge needle column (18). The experimental support (11) is equipped with a discharge needle (19); a light source (10) and a high-speed camera (13) are provided on both sides of the experimental support (11); the high-speed camera (13) is paired with a signal acquisition instrument (14) to capture the process of electric spark bubbles contacting the experimental cylinder; the high-voltage control box (15) is connected to the discharge needle (19) through a wire, and is connected to the high-speed camera (13) and the signal acquisition instrument (14) through a synchronization sensor to ensure that the high-voltage control box (15), the high-speed camera (13) and the signal acquisition instrument (14) work synchronously; The first experimental cylinder mounting mechanism includes a first experimental cylinder (9) and two sets of sliding positioning plates (7). The spacing between the two sets of sliding positioning plates (7) is adapted to the first experimental cylinder (9). The upper end of the first experimental cylinder (9) is fixed to the lower end of the two sets of sliding positioning plates (7). The second experimental cylinder mounting mechanism includes a second experimental cylinder (1) and two sets of sliding plates, the spacing of which is adapted to the second experimental cylinder (1); the sliding plates include an upper annular mounting port (71) and a lower slide rail (2); the two ends of the second experimental cylinder (1) are respectively set in the lower slide rail (2) of the two side sliding plates.

2. An experimental method based on the experimental apparatus described in claim 1 for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets, characterized in that, Includes the following steps: Step 1: Design the first experimental cylinder (9) and the second experimental cylinder (1) based on the target of small size and small mass; The first experimental cylinder (9) is a complete cylinder, and the second experimental cylinder (1) has grooves at both ends. The first experimental cylinder (9) and the second experimental cylinder (1) have the same radius and mass. Step 2: Arrange the slot plate (3) vertically and install it at the lower end of the structural frame (6). After adjusting the spacing of the two sets of sliding positioning plates (7), fix the upper end of the first experimental cylinder (9) to the lower end of the two sets of sliding positioning plates (7) and fix the upper end of the two sets of sliding positioning plates (7) in the slot (31) of the slot plate (3). Step 3: Fill the experimental water tank (12) with water, and adjust the longitudinal position of the electric spark base (17) according to the experimental content so that the first experimental cylinder (9) and the discharge needle (19) are below the water surface and the distance between the first experimental cylinder (9) and the discharge needle (19) meets the experimental requirements; adjust the light source (10) and the high-speed camera (13) so that the light intensity of the light source (10) meets the experimental requirements, and make the shooting position of the light source (10) and the high-speed camera (13) on the same horizontal line as the discharge needle (19); Step 4: Start the experiment of the first experimental cylinder (9). Use the high voltage control box (15) to make the underwater discharge needle (19) generate underwater bubbles. The high-speed camera (13) and the signal acquisition instrument (14) work synchronously. Step 5: Unload the first experimental cylinder (9), sliding positioning piece (7) and slot plate (3); arrange the slot plate (3) horizontally and install it at the lower end of the structural frame (6). Fit the upper annular mounting opening (71) of the two sets of sliding pieces into the two slots (31) of the slot plate (3) through the positioning slider (4). After adjusting the distance between the two sets of sliding pieces by sliding the positioning slider (4), set the left and right ends of the second experimental cylinder (1) in the lower slide rail (2) of the two side sliding pieces. Fix the two sets of positioning sliders (4) in the positioning opening (32) of the slot plate (3). Step 6: Adjust the water level in the experimental water tank (12), the initial position and distance between the second experimental cylinder (1) and the discharge needle (19), and the shooting position of the light source (10) and the high-speed camera (13) to be consistent with Step 3; Step 7: Start the experiment of the second experimental cylinder (1). The underwater discharge needle (19) is made to generate the same underwater bubbles as in step 4 by the high voltage control box (15). The second experimental cylinder (1) moves vertically along the lower slide rail (2) of the two sides of the slide plate due to the explosion of the bubbles. The high-speed camera (13) and the signal acquisition instrument (14) work synchronously. Step 8: Based on the video captured by the high-speed camera (13), process frame by frame, convert each frame image into a grayscale image, apply Gaussian blur to smooth the image, and then obtain the outlines of the bubble and the first experimental cylinder (9) and the second experimental cylinder (1) through edge detection and binary filling. Features were extracted from each connected region of the bubble contour. Based on the image size and scale, the variation law of bubble pulsation velocity with distance parameter in the two experiments was obtained. Feature points were extracted from each connected region of the first experimental cylinder (9) and the second experimental cylinder (1). The displacement of the second experimental cylinder (1) was identified. The Hearst exponent of the displacement time series was calculated based on the rescaled range analysis method. The nonlinear motion law of the second experimental cylinder (1) was obtained based on the Hearst exponent. The experiment of underwater near-field explosion attacking small-sized and small-mass targets was completed.

3. The experimental method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets according to claim 2, characterized in that: In step 2, the slotted plate (3) is arranged vertically and fixed to the lower end of the structural frame (6) by bolts at the four corners.

4. The experimental method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets according to claim 2, characterized in that: In step 2, the upper end of the sliding positioning piece (7) is fixed in two slots (31) on the slot plate (3) by positioning bolts (20).

5. An experimental method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets according to claim 2, characterized in that: In step 2, the upper end of the first experimental cylinder (9) is fixed to the lower end of the sliding positioning piece (7) by eye screws (8).

6. The experimental method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets according to claim 2, characterized in that: In step 5, the slotted plate (3) is arranged horizontally and fixed to the lower end of the structural frame (6) by the corner brackets (5) at the four corners.

7. The experimental method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets according to claim 2, characterized in that: In step 5, the annular mounting port (71) of the slide plate has mounting holes on both sides of the upper part, and is connected to the lower sides of the positioning slider (4) by bolts.

8. An experimental method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets according to claim 2, characterized in that: In step 5, the two sets of positioning sliders (4) are fixed in the positioning opening (32) of the slot plate (3) by locking bolts (21).

9. An experimental method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets according to claim 2, characterized in that: In step 8, features are extracted from each connected region of the bubble profile. After the bubble reaches its maximum radius, the moment when the fill degree is less than 0.3 is the moment the bubble bursts. The curves of the change in bubble radius and fill degree are plotted. The expansion rate is defined as a positive value and the contraction rate as a negative value. The curves of bubble radius change with time, bubble expansion rate change with time, and bubble longitudinal position and longitudinal velocity change with time are plotted to obtain the variation law of bubble pulsation velocity with distance parameter in the two experiments.

10. An experimental method for investigating the attack effect of underwater near-field explosions on small-sized, low-mass targets according to claim 2, characterized in that: The calculation of the Hearst exponent of the displacement time series in step 8 based on the rescaled range analysis method is as follows: The mean of a time series is calculated using rescaled range analysis. The time series X = {X1, X2, ..., X...} N }, where N represents the length of the sequence, and X represents the time series of displacement, velocity, and acceleration. First, calculate the mean of the time series: Calculate the deviation sequence Y i for: Calculate the cumulative deviation sequence Z i : The range of a cumulative deviation series is defined as: R(N)=max(Z1,Z2,…,Z N )-min(Z1,Z2,…,Z N ) That is, calculate the difference between the maximum and minimum values ​​of the Z-sequence; The standard deviation S(N) of the time series X is: According to the rescaled range analysis method, the relationship between the rescaled range R / S and the time scale N follows a power law: Taking the logarithm transforms both sides into a linear relationship: The slope H is obtained through linear regression, and this value is the Hearst exponent.

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