Water entry experiment system of underwater vehicle and experiment method thereof

Abstract

The invention provides a water entry experiment system of an underwater vehicle and an experiment method of the water entry experiment system, and belongs to the technical field of underwater vehicle experiments. Comprising a water tank, a high-speed camera and a launching assembly, the top of the water tank is open, an elastic bullet attaching layer is arranged at the bottom of the water tank, the high-speed camera is arranged beside the water tank, the launching assembly comprises a coil gun launcher and a control unit, and the coil gun launcher comprises a launching support, a gun barrel, a coil, a photoelectric switch and a capacitor; the multiple sections of coils are wound on the gun barrel in the length direction of the gun barrel, each section of coil is correspondingly connected with a capacitor, a photoelectric switch is arranged between every two adjacent coils, the control unit comprises a controller, an external power supply, a boost switch and a silicon controlled trigger switch, and each section of coil is connected with the corresponding capacitor in series through the silicon controlled trigger switch. By optimizing and improving the defects of the traditional experimental device for the supercavitation projectile, the accuracy and reliability of the experiment can be improved.

Description

Technical Field

[0001] This invention relates to the field of underwater vehicle testing technology, and in particular to an underwater vehicle entry testing system and method. Background Technology

[0002] Because water is much denser than air, conventional underwater vehicles experience significantly greater drag, generally limiting their speed to 40 knots and resulting in shorter ranges. To improve underwater speed and achieve greater range, numerous scholars and engineers both domestically and internationally have proposed various methods for drag reduction and speed increase, such as drag reduction through surface vibration, shape optimization, hydrophobic surface treatment, and supercavitation. Among these, supercavitation technology is a cutting-edge fluid dynamics technique that significantly reduces water resistance by enveloping the underwater vehicle in gas bubbles through special shape design or ventilation methods. Applying this technology to underwater projectiles can achieve extremely high underwater speeds and ranges, showing significant potential for both military and civilian applications.

[0003] In related technologies, to study the water entry process, cavitation generation, and ballistic characteristics of supercavitating projectiles, physical simulation experiments need to be conducted in a laboratory environment. Currently, publicly available experiments generally employ launching devices powered by high-pressure compressed gas. These devices typically consist of a high-pressure gas source, a quick-opening valve, a launch tube, and a velocity measurement system. The instantaneously released high-pressure gas propels the projectile within the launch tube, accelerating it to a preset water entry velocity.

[0004] However, to accelerate the projectile to high speeds, the required gas pressure and storage volume necessitate a large overall size for the launching device, its supporting gas supply system, and related stabilizing support structures. This places stringent demands on the space, load-bearing capacity, and safety of the experimental site, resulting in poor experimental flexibility and economy. More critically, during high-speed propulsion, the projectile inevitably experiences intense friction and collision with the inner wall of the launch tube, easily leading to subtle plastic deformation of the projectile itself and the internal structure of the launching device. This deformation can cause unexpected attitude disturbances upon water entry, and the change in drag can interfere with the precise achievement of the preset incident velocity. All these factors combined result in poor controllability of the experimental process, ultimately affecting the accuracy and reliability of the experimental data, making it difficult to support precise research on the mechanism of supercavitation water entry. Summary of the Invention

[0005] This invention provides a water entry test system and method for underwater vehicles, optimizing and improving upon the shortcomings of traditional supercavitating projectile test devices to enhance the accuracy and reliability of the experiment. The technical solution is as follows: In a first aspect, embodiments of the present invention provide a water entry test system for an underwater vehicle, comprising: A water tank, wherein the top of the water tank is open and the bottom is provided with an elastic cushioning layer; A high-speed camera is installed beside the water tank; The launching assembly includes a coilgun launcher and a control unit. The coilgun launcher includes a launching bracket, a barrel, a coil, a photoelectric switch, and a capacitor. The barrel is fixedly mounted on the launching bracket and includes a loading end and an outlet end facing the water tank. The coil has multiple segments wound around the barrel along its length. Each segment of the coil is connected to a corresponding capacitor. A photoelectric switch is provided between adjacent ends of the coils. The control unit includes a controller, an external power supply, a boost switch, and a thyristor trigger switch. Each segment of the coil is connected in series with a corresponding capacitor via the thyristor trigger switch. The controller is configured as follows: When an external charging control command is received, the boost switch is triggered to conduct so that the capacitor can be charged using an external power source; When a launch command is received, or when a high-level signal is received from the photoelectric switch, the thyristor trigger switch is triggered to conduct, so that the capacitor discharges to the corresponding coil and generates a magnetic field, thereby accelerating the projectile passing through the coil inside the gun barrel. When an image acquisition command is received, the high-speed camera is controlled to capture images of the projectile entering the water.

[0006] Optionally, the controller is configured to: when both the launch command and the image acquisition command are received simultaneously, trigger the thyristor trigger switch connected to the coil closest to the loading end to conduct.

[0007] Optionally, the launch bracket is externally wrapped with a non-magnetic insulating layer.

[0008] Optionally, the gun barrel is a ceramic tube.

[0009] Optionally, the controller includes a control panel mounted on the launch bracket and a host computer, wherein the control panel is communicatively connected to the host computer.

[0010] Optionally, it also includes an angle adjustment device, which is disposed at the top opening of the water tank and connected to the firing bracket, for adjusting the firing angle of the gun barrel.

[0011] Optionally, a horizontally arranged mounting rail is provided on one side of the top of the water tank. The angle adjustment device includes a fixed angle bracket and an arc-shaped connector disposed above the fixed angle bracket. The fixed angle bracket is connected to the mounting rail by bolts. The arc-shaped connector is provided with two concentrically arranged arc-shaped adjustment grooves. The firing bracket is provided with a bolt fixing groove parallel to the gun barrel. The firing bracket is connected to the arc-shaped connector by bolts through the bolt fixing groove and the arc-shaped adjustment groove.

[0012] Optionally, it also includes lighting components, including LED square lights and a soft light screen, wherein multiple LED square lights are arranged around the water tank, and the soft light screen and the high-speed camera are arranged on opposite sides of the water tank.

[0013] Optionally, the projectile body is a pure iron projectile body.

[0014] Secondly, embodiments of the present invention also provide an experimental method, implemented based on the underwater vehicle entry test system described in the first aspect, comprising: Step 1: Fill the water tank with water through the top opening, and adjust the relative position of the firing bracket and the water tank so that the outlet end of the gun barrel faces the water tank and has a preset firing angle; Step 2: Load the projectile into the gun barrel from the loading end. Send an external charging control command to the controller manually or via the host computer to trigger the boost switch to turn on so as to charge the capacitor using an external power source, and start the photoelectric switch to be in monitoring mode. Step 3: Send a launch command and an image acquisition command to the controller manually or via a host computer to trigger the thyristor trigger switch connected to the coil closest to the loading end, so that the corresponding coil discharges and generates a magnetic field to accelerate the projectile located at the loading end; Step 4: When the projectile passes the position of the photoelectric switch inside the barrel, the photoelectric switch outputs a high-level signal to trigger the thyristor trigger switch to turn on, causing the capacitor to discharge to the corresponding coil and generate a magnetic field, which accelerates the projectile passing through the coil inside the barrel step by step until the projectile leaves the barrel and is fired at its final speed. Step 5: Use the high-speed camera to film the process of the projectile entering the water.

[0015] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: The problem of the large size of traditional launching devices has been solved: the use of coil gun launchers to replace traditional high-pressure gas guns eliminates the need for a large high-pressure gas source system and stable support structure, significantly reducing the size and lowering the requirements for experimental space, load-bearing capacity and safety, while improving the flexibility and economy of the experiment.

[0016] The problem of deformation caused by friction between the projectile and the launch tube has been solved: the acceleration principle of the coilgun launcher is to accelerate the projectile non-contactly by electromagnetic force. There is only necessary radial support between the projectile and the gun barrel. There is no severe axial friction and collision caused by gas propulsion in traditional air guns. This avoids plastic deformation of the projectile itself and the inside of the launching device, and improves the stability of the projectile's water entry attitude and the accuracy of the incident velocity.

[0017] The problem of poor speed control accuracy has been solved: by adjusting the charging voltage of the capacitor and the number of coil stages, the final speed of the projectile can be precisely controlled; by synchronous triggering control of the photoelectric switch, each coil segment is ensured to be energized at the optimal time to maximize acceleration efficiency; and by using the shielding effect of the non-magnetic insulation layer, electromagnetic leakage interference with the projectile's motion is avoided, thus comprehensively improving the accuracy and repeatability of speed control.

[0018] The accuracy and reliability of experimental data were improved: the synchronous triggering mechanism of the high-speed camera and the launch component ensured accurate capture of critical moments; the surround illumination configuration and soft light processing improved image clarity and contrast; the angle adjustment device enabled precise control of the launch angle; and the excellent magnetic properties of the pure iron projectile body ensured the stability of electromagnetic acceleration. These improvements comprehensively enhanced the completeness, accuracy, and reliability of the experimental data, providing a reliable experimental platform for studying the water entry mechanism of supercavitating projectiles. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of an underwater vehicle entry test system provided in an embodiment of the present invention; Figure 2 This is a partial structural schematic diagram of the coilgun launcher provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the coilgun launcher provided in an embodiment of the present invention without a non-magnetic insulating layer; Figure 4 This is a schematic diagram of the structure of the coilgun launcher provided in an embodiment of the present invention after being wrapped with a non-magnetic insulating layer; Figure 5 This is a schematic diagram of the angle adjustment device provided in an embodiment of the present invention; Figure 6 This is a block diagram of the control structure of the control unit provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the control structure of a single-segment coil provided in an embodiment of the present invention; Figure 8 This is a flowchart of the experimental method provided in the embodiments of the present invention.

[0021] In the picture: 1-Water tank; 2-High-speed camera; 3-Launch assembly; 4-Angle adjustment device; 5-Illumination assembly; 11-Elastic impact layer; 12-Mounting rail; 31-Coil ballistic missile launcher; 32-Control unit; 41-Fixing angle bracket; 42-Arc connector; 51-LED square light; 52-Soft light screen; 311-Launch bracket; 312-Cannon barrel; 313-Coil; 314-Photoelectric switch; 315-Capacitor; 316-Non-magnetic insulation layer; 321-Controller; 322-External power supply; 323-Boost switch; 324-SCR trigger switch; 421-Arc adjustment groove; 3111-Bolt fixing groove; 3211-Control panel; 3212-Host computer; 312a-Loading end; 312b-Exit end; 311a-Bottom mounting beam; 311b-Mounting box. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the overall structure of an underwater vehicle entry test system provided in an embodiment of the present invention; Figure 2 This is a partial structural schematic diagram of the coilgun launcher provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the coilgun launcher provided in an embodiment of the present invention without a non-magnetic insulating layer; Figure 4 This is a schematic diagram of the structure of the coilgun launcher provided in an embodiment of the present invention after being wrapped with a non-magnetic insulating layer; Figure 5 This is a schematic diagram of the angle adjustment device provided in an embodiment of the present invention; Figure 6 This is a block diagram of the control structure of the control unit provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the control structure of a single-segment coil provided in an embodiment of the present invention. Figures 1 to 7 As shown, this embodiment of the invention provides a water entry test system for an underwater vehicle, including a water tank 1, a high-speed camera 2, and a launching component 3.

[0024] The water tank 1 has an opening at the top and an elastic projectile-bearing layer 11 at the bottom. A high-speed camera 2 is positioned beside the water tank 1. The launching assembly 3 includes a coilgun launcher 31 and a control unit 32. The coilgun launcher 31 includes a launching bracket 311, a barrel 312, a coil 313, a photoelectric switch 314, and a capacitor 315. The barrel 312 is fixedly mounted on the launching bracket 311 and includes a loading end 312a and an outlet end 312b facing the water tank 1. The coil 313 has multiple segments wound around the barrel 312 along its length. Each segment of the coil 313 is connected to a corresponding capacitor 315. A photoelectric switch 314 is positioned between adjacent ends of the coil 313. The control unit 32 includes a controller 321, an external power supply 322, a boost switch 323, and a thyristor trigger switch 324. Each segment of the coil 313 is connected in series with a corresponding capacitor 315 via the thyristor trigger switch 324. The controller 321 is configured as follows: When an external charging control command is received, the boost switch 323 is triggered to turn on so that the capacitor 315 can be charged using the external power supply 322. When a launch command is received, or when a high-level signal is received from photoelectric switch 314, the thyristor trigger switch 324 is triggered to conduct, so that capacitor 315 discharges to the corresponding coil 313 and generates a magnetic field, which accelerates the projectile passing through coil 313 inside the barrel 312. When an image acquisition command is received, the high-speed camera 2 is controlled to take pictures of the projectile entering the water.

[0025] In this embodiment of the invention, the water tank 1 is an open-type experimental water tank with a top opening design that facilitates water filling and projectile immersion experiments from above. An elastic impact layer 11, made of rubber and approximately 20mm thick, is provided at the bottom of the water tank 1. The purpose of the elastic impact layer 11 is to buffer the impact force of the projectile on the bottom of the water tank when it enters the water at high speed and sinks to the bottom, preventing direct collision that could damage the water tank or deform the projectile structure, thereby protecting the experimental equipment and personnel. This design solves the problem of equipment damage and safety hazards that may result from direct impact of the projectile on the bottom of the water tank in traditional immersion experiments.

[0026] In the preferred embodiment, the internal dimensions of the water tank 1 are 2m × 1.2m × 1.5m, constructed from double-layered 10mm tempered glass, providing excellent transparency and structural strength. The water tank 1 not only has an elastic impact layer 11 at the bottom, but also approximately 20mm thick rubber pads on both sides to cushion the impact that the projectile may experience upon entering the water. This comprehensive cushioning design ensures the safety and repeatability of the experimental process.

[0027] The high-speed camera 2 is positioned beside the water tank 1, preferably at the front of the water tank 1. The main function of the high-speed camera 2 is to observe the flow phenomena on the free surface of the liquid, the underwater cavitation evolution process of the rotating body, and its underwater trajectory. Through high-speed imaging technology, the formation, development, and closure of cavitation bubbles at the moment the projectile enters the water can be captured, providing reliable experimental data for studying the hydrodynamic characteristics of supercavitating projectiles.

[0028] In a specific embodiment of this solution, the high-speed camera 2 can be a Phantom V611 model, equipped with a 105mm f / 2.8 Nikon lens. The camera frame rate is set to 5000fps, with a frame interval of 200μs, allowing for continuous recording and data storage for 2 seconds. Shooting is performed at full resolution of 1280×800, enabling it to adapt to the unpredictable motion trajectories of rotating bodies with different initial tilt angles within the water tank.

[0029] The launching assembly 3 includes a coilgun launcher 31 and a control unit 32. Compared with traditional high-pressure gas cannon launching devices, the coilgun launcher 31 has advantages such as small size, high energy conversion efficiency, no mechanical contact, and no ablation or wear, fundamentally solving the problems of large size, deformation caused by friction between the projectile and the launching tube, and poor velocity control accuracy of traditional launching devices. Among them, the launching bracket 311 is the overall support structure of the coilgun launcher 31, providing structural support for the entire coilgun. The launching bracket 311 includes a bottom mounting beam 311a made of aluminum material and a mounting box 311b fixed to the bottom mounting beam 311a by bolts. The coilgun launcher 31 is supported by the metal bottom mounting beam 311a, and the 3D-printed mounting box 311b completely encloses the part of the coilgun launcher 31 except for the exit end 312b of the barrel 312, avoiding water splashes that may come into contact with the relevant electronic control components during the experiment. It has the characteristics of light weight, high strength, and high safety. The launch bracket 311 can be used in conjunction with the angle adjustment device 4 to enable the projectile to enter the water at different angles.

[0030] The gun barrel 312 is fixedly mounted on the firing bracket 311, with a loading end 312a and an exit end 312b at its two ends. The loading end 312a is used to load the projectile into the gun barrel 312, and the exit end 312b is arranged facing the water tank 1 so that the projectile can directly enter the water tank 1 for water entry testing after being fired. The inner diameter of the gun barrel 312 matches the diameter of the projectile; in one specific embodiment, the inner diameter of the gun barrel 312 is 6 mm.

[0031] The coil 313 has multiple segments and is wound around the gun barrel 312 along its length. The multiple coil segments 313 are arranged sequentially along the axial direction of the gun barrel 312, forming a multi-stage acceleration structure. In a specific embodiment of this design, the coil 313 can be configured as six segments (i.e., a six-stage acceleration coil), each segment having a length of 28 mm, an outer diameter of 20 mm, an inner diameter of 6 mm, and 168 turns. The coil 313 is made of copper material, which has good electrical conductivity.

[0032] Capacitor 315 serves as an energy storage element, and each segment of coil 313 is connected to a corresponding capacitor 315. After storing energy, capacitor 315 rapidly releases it, forming a transient high-energy pulse that provides discharge current to coil 313. In a specific embodiment of this solution, capacitor 315 has a capacitance of 1000μF and a rated voltage of 450V.

[0033] A photoelectric switch 314 is positioned between two adjacent coil segments 313. The photoelectric switch 314 detects the position of the projectile within the barrel 312 and outputs a trigger signal. The photoelectric switch 314 includes an infrared emitter and an infrared receiver, forming a photoelectric detection pair. The infrared emitter emits infrared light of a specific wavelength (approximately 940nm), and the infrared receiver receives the emitted light. Under normal conditions (when the optical path is unobstructed), the photoelectric switch 314 outputs a low level; when the projectile passes by, it blocks the optical path, causing a change in the resistance of the receiver and resulting in a high-level trigger signal.

[0034] In the control unit 32, the controller 321 is the core component, responsible for coordinating the working timing of each component. The controller 321 is electrically connected to the photoelectric switch 314, the thyristor trigger switch 324, the boost switch 323, and the high-speed camera 2, achieving unified control. An external power supply 322 provides power to the entire system. The boost switch 323 is connected between the external power supply 322 and the capacitor 315. When the boost switch 323 is turned on, the power from the external power supply 322 is boosted by the boost circuit to charge the capacitor 315. Multiple thyristor trigger switches 324 are provided, with each coil 313 connected in series with its corresponding capacitor 315 via a thyristor trigger switch 324. The thyristor trigger switches 324 are used to control the discharge timing of the capacitor 315 to the coil 313. When the thyristor trigger switch 324 receives the trigger signal and turns on, the energy storage capacitor 315 and the corresponding coil 313 form a closed circuit. The electrical energy stored in the capacitor 315 is released rapidly in the form of pulse current. The coil 313 instantly generates a strong magnetic field, which applies electromagnetic force to the projectile to accelerate it.

[0035] Furthermore, controller 321 is configured to implement the following control logic: Charging control: When an external charging control command is received, the controller 321 triggers the boost switch 323 to turn on, using the external power supply 322 to charge each capacitor 315. Current flows through the current-limiting resistor, and the capacitors 315 are gradually fully charged. The controller 321 can display the charging voltage in real time. When the voltage reaches a reference value (e.g., 380V), charging is complete, and the coilgun launcher 31 is in the pre-firing state.

[0036] Launch control: When a launch command is received, or when a high-level signal is received from photoelectric switch 314, controller 321 triggers the corresponding thyristor trigger switch 324 to conduct. After the thyristor trigger switch 324 is conducted, capacitor 315 discharges to the corresponding coil 313 and generates a magnetic field, which accelerates the projectile passing through the coil 313 inside the barrel 312.

[0037] The specific launch control process is as follows: First, the thyristor trigger switch 324 connected to the first-stage coil 313 is directly triggered and turned on, initially accelerating the projectile. When the projectile flies to the position of the photoelectric switch 314 at the front end of the second-stage coil 313, the projectile blocks the infrared light path, and the photoelectric switch 314 outputs a high-level signal, triggering the second-stage thyristor trigger switch 324 to turn on, accelerating the projectile a second time. This process continues, with the projectile being accelerated sequentially by each stage of the coil 313, the velocity continuously increasing until it leaves the barrel 312 and is fired at its final velocity.

[0038] Image acquisition control: When an image acquisition command is received, the controller 321 controls the high-speed camera 2 to start and record the entire process of the projectile entering the water.

[0039] Through the above control logic, the controller 321 realizes the synchronous triggering of the projectile launch and the high-speed camera 2 shooting, ensuring that the instantaneous process of the projectile entering the water can be completely recorded.

[0040] Optionally, the controller 321 is configured to activate the thyristor trigger switch 324 connected to the coil 313 closest to the loading end 312a when both a launch command and an image acquisition command are received simultaneously. Exemplarily, in a preferred embodiment of the present invention, the control strategy of the controller 321 is further optimized. To achieve simultaneous activation of the moving body launch, high-speed camera 2 image capture, and data recording functions, the controller 321 connects the coilgun launcher 31 and the high-speed camera 2 for coordinated control.

[0041] Specifically, to prevent accidental activation and other potentially dangerous operations, the controller 321 is equipped with a safety interlock mechanism. When the system is in the pre-launch state after charging is complete, simply activating the launch button will not produce any response. Only when the launch button and the image acquisition button are activated simultaneously (i.e., when the controller 321 receives both the launch command and the image acquisition command at the same time) will the coilgun launcher 31 launch the projectile, and the high-speed camera 2 will be triggered to acquire image information. This synchronous trigger control ensures that safety accidents caused by misoperation are avoided; the precise synchronization between projectile launch and high-speed camera 2 imaging ensures that the critical moment of projectile entry into the water is not missed; and it simplifies the overall operation process and improves experimental efficiency.

[0042] Optionally, the launching bracket 311 is externally wrapped with a non-magnetic insulating layer 316. Exemplarily, in this embodiment of the invention, during the experiment, it was found that when a projectile accelerated by the coilgun leaves the barrel 312, it may not move linearly along its own axis but instead undergoes random motion. Analysis revealed that this problem is mainly caused by the following reasons: During operation, the acceleration coils 313 at each stage are energized and de-energized sequentially. When the projectile passes through a certain acceleration coil 313, the coil is energized, generating a magnetic field, and the projectile accelerates. After the projectile leaves, the coil needs to be de-energized immediately. However, due to the response delay of the switching devices, when the projectile leaves the barrel 312, the final stage coil may still have residual current, and an incompletely decaying magnetic field still exists around the coil. Since the projectile is ferromagnetic, it will be magnetized by the residual magnetic field and subjected to Ampere force. Although the intensity of the residual magnetic field is lower than during the acceleration phase, due to the small size and light weight of the projectile, it may still interfere with the projectile's trajectory.

[0043] To address the aforementioned electromagnetic leakage issue, in this embodiment, the launching bracket 311 is externally wrapped with a non-magnetic insulating layer 316. The non-magnetic insulating layer 316 can be made of tin foil, which is tightly wrapped around the entire outer shell of the coilgun to reduce electromagnetic penetration and effectively avoid electromagnetic interference.

[0044] Tin foil material has excellent electromagnetic shielding properties, and is also lightweight, low-cost, and easy to process. By wrapping it with a non-magnetic insulating layer 316, the electromagnetic field generated by the coil 313 can be effectively shielded from leakage, ensuring the stability of the projectile's trajectory after leaving the barrel 312, and improving the reliability and repeatability of the experiment.

[0045] Optionally, the barrel 312 is a ceramic tube. Exemplarily, in this embodiment of the invention, a silicon carbide ceramic tube is used as the barrel 312. Silicon carbide ceramics possess high hardness, high strength, and high wear resistance, enabling them to withstand the friction and impact of repeated projectile firing without easily deforming. Furthermore, silicon carbide is a non-magnetic material and will not be magnetized by the magnetic field generated by the coil 313, effectively avoiding electromagnetic interference. As an insulating material, it also prevents electrical short circuits between the coils 313, and its low coefficient of thermal expansion ensures dimensional stability during operation, guaranteeing the alignment of the barrel 312. In summary, by using a silicon carbide ceramic tube as the barrel 312, while ensuring mechanical performance, its non-magnetic and insulating properties effectively avoid electromagnetic interference, enabling the projectile to move stably along a predetermined trajectory, thus improving the accuracy and reliability of the experiment.

[0046] Optionally, the controller 321 includes a control panel 3211 mounted on the launching bracket 311 and a host computer 3212, with the control panel 3211 and the host computer 3212 communicatively connected. Exemplarily, in this embodiment of the invention, the control panel 3211 is directly mounted on the launching bracket 311, specifically located on the loading end 312a side of the barrel 312, facilitating on-site loading and further operations by experimental personnel. The control panel 3211 is equipped with operation and display elements such as a charging button, a firing button, a data acquisition button, and a voltage display screen. The voltage display screen is used to display the charging voltage of the capacitor 315 in real time. When the voltage reaches a reference value (e.g., 380V), it indicates that charging is complete and the coilgun launcher 31 is in a pre-firing state. Experimental personnel can manually control charging, firing, and data acquisition operations via the buttons on the control panel 3211.

[0047] The host computer 3212 is typically a computer or other intelligent terminal device, which communicates with the control panel 3211. The host computer 3212 can remotely send various control commands to the controller 321, including external charging control commands, transmission commands, and image acquisition commands. Simultaneously, the host computer 3212 can also receive image data captured by the high-speed camera 2, and perform storage and post-processing analysis.

[0048] By configuring the control panel 3211 and the host computer 3212, the controller 321 can achieve two operating modes: Manual operation mode: The experimenter operates the equipment on-site through the buttons on the control panel 3211, which is suitable for single experiments or debugging phases.

[0049] Remote operation mode: Experimenters can remotely send control commands through the host computer 3212, which is suitable for batch experiments or situations where it is necessary to be far away from the experimental site, thus improving experimental safety.

[0050] Specifically, the communication connection between the control panel 3211 and the host computer 3212 can be a wired connection (such as RS232, RS485, USB, etc.) or a wireless connection (such as WiFi, Bluetooth, etc.), and the configuration can be selected according to actual needs.

[0051] Optionally, an angle adjustment device 4 is also included, disposed at the top opening of the water tank 1 and connected to the launching bracket 311, for adjusting the launching angle of the gun barrel 312. Exemplarily, in this embodiment of the invention, the angle adjustment device 4 enables the projectile to undergo water entry experiments at different water entry angles. The water entry angle is one of the important parameters in the water entry experiment; different water entry angles result in different cavitation morphologies and trajectories after the projectile enters the water. The angle adjustment device 4 allows for convenient adjustment of the launching angle of the gun barrel 312, meeting the experimental requirements under different working conditions.

[0052] Specifically, a horizontally arranged mounting rail 12 is provided on one side of the top of the water tank 1. The angle adjustment device 4 includes a fixed angle bracket 41 and an arc-shaped connector 42 disposed above the fixed angle bracket 41. The fixed angle bracket 41 is bolted to the mounting rail 12. The arc-shaped connector 42 is provided with two concentrically arranged arc-shaped adjustment grooves 421. The firing bracket 311 is provided with a bolt fixing groove 3111 parallel to the barrel 312. The firing bracket 311 and the arc-shaped connector 42 are bolted together through the bolt fixing groove 3111 and the arc-shaped adjustment groove 421. The fixed angle bracket 41 is bolted to the mounting rail 12. The fixed angle bracket 41 can slide along the mounting rail 12 to adjust the horizontal position of the coilgun launcher 31, so that the outlet end 312b of the barrel 312 is aligned with the predetermined water inlet point in the water tank 1. After adjustment, the fixed angle bracket 41 is fixed to the mounting rail 12 by tightening the bolts. An arc-shaped connector 42 is integrally mounted above the fixed angle bracket 41. The arc-shaped connector 42 has two concentrically arranged arc-shaped adjustment slots 421. These two arc-shaped adjustment slots 421 are arranged around the same center, allowing the launch bracket 311 to rotate around this center. The launch bracket 311 and the arc-shaped connector 42 are bolted together via bolt fixing slots 3111 and the arc-shaped adjustment slots 421. Specifically, on one side of the launch bracket 311, two bolts are passed through the two arc-shaped adjustment slots 421 on the arc-shaped connector 42 and the bolt fixing slots 3111 on the launch bracket 311, and tightened to secure them. Specifically, two angle adjustment devices 4 can be provided, fixing the launch bracket 311 from both sides to improve assembly stability. The overall assembly structure is simple, easy to adjust, accurately positioned, and reliably fixed, meeting the experimental requirements for different water entry angles.

[0053] Optionally, the system also includes an illumination assembly 5, comprising LED square lamps 51 and a soft light screen 52. Multiple LED square lamps 51 are arranged around the water tank 1, and the soft light screen 52 and the high-speed camera 2 are positioned on opposite sides of the water tank 1. Exemplarily, in this embodiment of the invention, sufficient and uniform illumination is required to ensure that the high-speed camera 2 obtains a clear image. Multiple LED square lamps 51 are arranged around the water tank 1 to illuminate the entire experimental flow field. Specifically, four 200W LED square lamps 51 are placed behind the water tank 1 to provide backlight illumination. The backlight illumination makes the projectile and cavitation appear as clear outlines in the image from the high-speed camera 2. A soft light screen 52 is installed between the rear of the water tank 1 and the LED square lamps 51, and the soft light screen 52 and the high-speed camera 2 are positioned on opposite sides of the water tank 1. The function of the soft light screen 52 is to reduce reflection and glare, provide uniform illumination, and make the captured image clearer. To further eliminate shadows and improve the shadow areas on the front of the projectile and cavitation in the photographed images, LED square lights 51 can be placed on both sides of the water tank 1 as auxiliary light sources. In one specific embodiment, a 100W LED square light 51 is placed on each side.

[0054] The aforementioned lighting configuration enables the acquisition of clear and uniform experimental images, facilitating subsequent analysis of the projectile's trajectory and cavitation evolution. The arrangement of lighting component 5 is crucial for the imaging quality of high-speed photography; a reasonable lighting configuration is the fundamental guarantee for obtaining high-quality experimental data.

[0055] Optionally, the projectile body is made of pure iron. Exemplarily, in this embodiment of the invention, pure iron is an excellent soft magnetic material with high saturation magnetic induction. Under the influence of the changing magnetic field generated by coil 313, the pure iron projectile body can quickly respond and induce current, interacting with the magnetic field to generate a large electromagnetic thrust. Due to the soft magnetic properties of pure iron, it will not generate an excessively strong residual magnetic field after magnetization, thus not adversely affecting the electromagnetic force during launch. Furthermore, pure iron has a low resistivity, resulting in minimal loss of induced current flowing within the projectile body, maximizing the utilization of electromagnetic energy for acceleration. The pure iron projectile body can quickly demagnetize after leaving the magnetic field, and will not be affected by external magnetic field interference due to magnetization, ensuring the stability of launch and the controllability of the projectile's trajectory.

[0056] In a specific embodiment, the projectile is a solid iron rotating body structure, and can be designed with different head shapes according to experimental requirements, including cylindrical, hemispherical, conical, and truncated conical shapes. The diameter of the projectile can be set to 6mm, the total length can be set to 24mm, and the mass is approximately 5g.

[0057] Figure 8 This is a flowchart of the experimental method provided in an embodiment of the present invention. For example... Figure 8 As shown, this embodiment of the invention also provides an experimental method based on, as Figures 1 to 7The underwater vehicle's water entry test system shown includes: S1. Water is injected into the water tank 1 through the top opening. The relative position of the firing bracket 311 and the water tank 1 is adjusted so that the outlet end 312b of the cannon barrel 312 faces the water tank 1 and has a preset firing angle.

[0058] Specifically, water is poured into the water tank 1 through the top opening until it reaches a suitable height. Based on the water level, the relative position of the launching bracket 311 and the water tank 1 is adjusted, including adjusting the height of the coilgun launcher 31 and adjusting the firing angle of the barrel 312 via the angle adjustment device 4, so that the outlet end 312b of the barrel 312 faces the water tank 1 and has a preset firing angle. The firing angle can be accurately read and recorded using an electronic level.

[0059] At the same time, the impact point of the projectile is estimated, the high-speed camera 2 is adjusted to a suitable position, and the focal length and image size are adjusted to ensure that the impact point is in the center of the captured image and to obtain a clear image.

[0060] S2. Load the projectile into the gun barrel 312 from the loading end 312a. Send an external charging control command to the controller 321 via manual or host computer 3212 to trigger the boost switch 323 to conduct so that the capacitor 315 can be charged by the external power supply 322, and start the photoelectric switch 314 to enter the monitoring state.

[0061] Specifically, the experimental projectile model was selected and recorded, and the projectile was loaded into the gun barrel 312 from the loading end 312a.

[0062] External charging control commands can be sent to the controller 321 manually (by operating the charging button on the control panel 3211) or by the host computer 3212. After receiving the external charging control command, the controller 321 triggers the boost switch 323 to conduct, using the external power supply 322 to charge each capacitor 315.

[0063] As capacitor 315 gradually charges, the voltage display on controller 321 shows the charging voltage in real time. When the voltage reaches a reference value (e.g., 380V), charging is complete, and coilgun launcher 31 is in pre-firing mode.

[0064] Simultaneously, photoelectric switch 314 is activated and enters monitoring mode. At this time, all thyristor trigger switches 324 are initially off, awaiting a trigger signal. The infrared emitting tube in photoelectric switch 314 continuously emits modulated infrared light, and the infrared receiving tube monitors the optical path in real time, outputting a low-level normal signal, ready to detect the projectile's position at any time.

[0065] S3. By manually or via the host computer 3212, a launch command and an image acquisition command are sent to the controller 321, triggering the thyristor trigger switch 324 connected to the coil 313 closest to the loading end 312a to conduct, so that the corresponding coil 313 discharges and generates a magnetic field, thereby accelerating the projectile located at the loading end 312a.

[0066] Specifically, the transmitter and image acquisition commands are sent to the controller 321 manually (by pressing the transmitter and acquisition buttons on the control panel 3211 simultaneously) or by the host computer 3212.

[0067] After receiving the firing command and the image acquisition command, the controller 321 triggers the thyristor trigger switch 324 connected to the coil 313 (i.e., the first-stage coil) closest to the loading end 312a. At this time, the thyristor trigger switch 324 is turned on, and the corresponding energy storage capacitor 315 forms an oscillating circuit with the first-stage coil 313. The discharge current generates a magnetic field in the first-stage coil 313, which applies a forward Lorentz force to the projectile. The projectile is pushed from a stationary state and accelerates forward along the axial direction of the gun barrel 312.

[0068] At the same time, the high-speed camera 2 is triggered to start acquiring image information at a preset frame rate (such as 5000fps).

[0069] S4. When the projectile passes the position of photoelectric switch 314 inside the barrel 312, the photoelectric switch 314 outputs a high-level signal to trigger the thyristor trigger switch 324 to conduct, causing capacitor 315 to discharge to the corresponding coil 313 and generate a magnetic field, which accelerates the projectile passing through coil 313 inside the barrel 312 step by step until the projectile leaves the barrel 312 and is fired at its final speed.

[0070] Specifically, when the projectile moves forward inside the barrel 312 and passes the position of the first photoelectric switch 314 (located between the first-stage coil 313 and the second-stage coil), the projectile blocks the infrared light path, and the photoelectric switch 314 outputs a high-level signal.

[0071] After receiving the high-level signal, the controller 321 triggers the thyristor trigger switch 324 connected to the second-stage coil 313 to turn on, causing the corresponding capacitor 315 to discharge to the second-stage coil 313 and generate a magnetic field, which applies a secondary electromagnetic thrust to the projectile that is located at the center of the coil, further increasing the speed of the projectile.

[0072] At the same time, as the voltage of capacitor 315 drops below the voltage corresponding to the holding current of the thyristor trigger switch 324, the first-stage coil 313 is automatically turned off, the current of the first-stage coil 313 decays to zero, the magnetic field disappears, and the reverse resistance to the projectile is avoided.

[0073] The projectile continues to fly forward, passing through each stage of photoelectric switches 314 and coils 313 in sequence, repeating the process of "monitoring → triggering, discharging, and accelerating". The projectile is accelerated by all stages of coils 313 in sequence, and the speed continues to accumulate until the projectile leaves the gun barrel 312 and is fired at its final speed.

[0074] S5. Use high-speed camera 2 to film the process of the projectile entering the water.

[0075] Specifically, a high-speed camera 2 is used to continuously film the entire process of the projectile entering the water. The high-speed camera 2 continuously acquires images at a preset frame rate, recording the entire process of water splashing, cavitation generation, cavitation evolution, and the underwater trajectory of the projectile at the moment of entry into the water.

[0076] After the image is captured, it is transmitted to the host computer 3212 for storage. By analyzing and processing the image data, key parameters such as the projectile's water entry velocity, water entry angle, trajectory, and cavitation morphology can be extracted to study the physical laws governing the projectile's water entry process.

[0077] To ensure the effectiveness and authenticity of the experiment, each experimental condition was repeated at least three times, and the best set of images was saved for later data analysis and numerical simulation results verification.

[0078] To avoid the randomness of the water entry experiment and ensure the reliability of the obtained experimental results, repeated experiments were conducted under various operating conditions. Verification showed that the relative deviations of the incident velocity and angle of this experimental system could be controlled within ±1.5%, the maximum repeatability error of the velocity value during water entry was less than 5%, and the maximum repeatability error of the angle value was less than 6%. These data indicate that this experimental system has high accuracy and repeatability, and the obtained experimental data has sufficient precision to analyze the physical problems during the projectile's water entry process.

[0079] The underwater vehicle entry test system provided in this embodiment of the invention, combined with the above-described experimental method, achieves the following technical effects: The problem of the large size of traditional launching devices has been solved: the coil gun launcher 31 replaces the traditional high-pressure gas gun, eliminating the need for a large high-pressure gas source system and stable support structure, greatly reducing the size and lowering the requirements for experimental site space, load-bearing capacity and safety, and improving the flexibility and economy of the experiment.

[0080] The problem of deformation caused by friction between the projectile and the launch tube has been solved: the acceleration principle of the coilgun launcher 31 is to accelerate the projectile by non-contact propulsion using electromagnetic force. There is only necessary radial support between the projectile and the cannon barrel 312. There is no severe axial friction and collision caused by gas propulsion in traditional air guns. This avoids plastic deformation of the projectile itself and the inside of the launching device, and improves the stability of the projectile's water entry attitude and the accuracy of the incident velocity.

[0081] The problem of poor speed control accuracy has been solved: by adjusting the charging voltage of capacitor 315 and the number of stages of coil 313, the final speed of the projectile can be precisely controlled; by synchronous triggering control of photoelectric switch 314, it is ensured that each segment of coil 313 is energized at the optimal time to maximize acceleration efficiency; by shielding the non-magnetic insulating layer 316, electromagnetic leakage is prevented from interfering with the projectile's motion, thus comprehensively improving the accuracy and repeatability of speed control.

[0082] The safety of the experiment is improved: the elastic impact layer 11 and the buffer protection design of the rubber pad effectively protect the experimental water tank and personnel safety; the waterproof and insulating properties of the non-magnetic insulating layer 316 avoid equipment short circuits and safety hazards caused by water splashing; the safety interlock mechanism of the controller 321 prevents dangerous operations such as accidental triggering.

[0083] The accuracy and reliability of experimental data were improved: the synchronous triggering mechanism of the high-speed camera 2 and the launch component 3 ensured accurate capture of critical moments; the surround illumination configuration and soft light processing improved image clarity and contrast; the angle adjustment device 4 enabled precise control of the launch angle; and the excellent magnetic properties of the pure iron projectile body ensured the stability of electromagnetic acceleration. These improvements comprehensively enhanced the completeness, accuracy, and reliability of the experimental data, providing a reliable experimental platform for studying the water entry mechanism of supercavitating projectiles.

[0084] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. “Up,” “down,” “left,” “right,” etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0085] The above description is merely an optional embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water entry test system for an underwater vehicle, characterized by, The application relates to a water tank (1) with an open top and an elastic baffle (11) at the bottom, a high-speed camera (2) arranged beside the water tank (1), a launching assembly (3) comprising a coil gun launcher (31) and a control unit (32), the coil gun launcher (31) comprising a launching support (311), a barrel (312), a coil (313), a photoelectric switch (314) and a capacitor (315), the barrel (312) being fixedly installed on the launching support (311) and comprising a loading end (312a) and an outlet end (312b) arranged towards the water tank (1), the coil (313) being arranged in multiple sections and being wound on the barrel (312) along the length direction of the barrel (312), each section of the coil (313) being connected with the capacitor (315), the photoelectric switch (314) being arranged between two adjacent sections of the coil (313), the control unit (32) comprising a controller (321), an external power supply (322), a voltage boosting switch (323) and a thyristor trigger switch (324), each section of the coil (313) being connected with the corresponding capacitor (315) in series through the thyristor trigger switch (324), and the controller (321) being configured to: trigger the voltage boosting switch (323) to conduct to charge the capacitor (315) with the external power supply (322) when receiving an external charging control instruction; trigger the thyristor trigger switch (324) to conduct when receiving a launching instruction or a high-level signal of the photoelectric switch (314), so that the capacitor (315) discharges to the corresponding coil (313) to generate a magnetic field and accelerate a bullet in the barrel (312) passing through the coil (313); and control the high-speed camera (2) to shoot the bullet entering the water when receiving an image collection instruction. The controller (321) is configured to trigger the thyristor trigger switch (324) connected with the coil (313) closest to the loading end (312a) to conduct when the launching instruction and the image collection instruction are simultaneously received. The launching support (311) is wrapped with a non-magnetic insulation layer (316) outside. The barrel (312) is a ceramic tube. The controller (321) comprises a control panel (3211) arranged on the launching support (311) and an upper computer (3212), and the control panel (3211) is in communication connection with the upper computer (3212). The application further comprises an angle adjusting device (4) arranged at the top opening of the water tank (1) and connected with the launching support (311) to adjust the launching angle of the barrel (312). ​ 2. The water entry test system of an underwater vehicle according to claim 1, wherein ​ 3. The water entry test system of an underwater vehicle according to claim 1, wherein ​ 4. The water entry test system of an underwater vehicle according to claim 1, wherein ​ 5. The water entry test system of an underwater vehicle according to claim 1, wherein ​ 6. The water entry test system of an underwater vehicle according to claim 1, wherein ​ 7. The water entry test system of an underwater vehicle according to claim 6, wherein The side of the top of the water tank (1) is provided with a transversely arranged mounting rail (12), the angle adjusting device (4) comprises a fixed angle code (41) and an arc-shaped connector (42) arranged above the fixed angle code (41), the fixed angle code (41) is connected with the mounting rail (12) through bolts, the arc-shaped connector (42) is provided with two concentrically arranged circular arc adjusting grooves (421), the launching support (311) is provided with a bolt fixing groove (3111) parallel to the cannon barrel (312), and the launching support (311) is connected with the arc-shaped connector (42) through the bolt fixing groove (3111) and the circular arc adjusting groove (421).

8. The water entry test system of an underwater vehicle according to any one of claims 1 to 7, characterized in that, Further comprising a lighting assembly (5) comprising LED square lamps (51) and soft light screens (52), a plurality of LED square lamps (51) are arranged around the water tank (1), and the soft light screens (52) are arranged on opposite sides of the water tank (1) with the high-speed camera (2).

9. The water entry test system of an underwater vehicle according to any one of claims 1 to 7, characterized in that, The elastic body is a pure iron elastic body.

10. An experimental method, implemented based on the water-entry experimental system of the underwater vehicle according to any one of claims 1 to 9, characterized in that, Comprise: Step 1, water is injected into the water tank (1) from the top opening, the relative position of the launching support (311) and the water tank (1) is adjusted so that the outlet end (312b) of the cannon barrel (312) faces the water tank (1) and has a preset launching angle; Step 2, the elastic body is loaded into the cannon barrel (312) from the loading end (312a), an external charging control instruction is sent to the controller (321) through manual or upper computer (3212), the boost switch (323) is triggered to be turned on to charge the capacitor (315) with an external power supply (322), and the photoelectric switch (314) is started to be in a monitoring state; Step 3, a launching instruction and an image acquisition instruction are sent to the controller (321) through manual or upper computer (3212), the thyristor trigger switch (324) connected with the coil (313) closest to the loading end (312a) is triggered to be turned on, so that the corresponding coil (313) is discharged and a magnetic field is generated, and the elastic body located at the loading end (312a) is accelerated; Step 4, when the elastic body passes the position of the photoelectric switch (314) in the cannon barrel (312), the photoelectric switch (314) outputs a high-level signal to trigger the thyristor trigger switch (324) to be turned on, so that the capacitor (315) discharges to the corresponding coil (313) and generates a magnetic field, and the elastic body passing the coil (313) in the cannon barrel (312) is accelerated step by step until the elastic body is shot out at a final speed; Step 5, the process of the elastic body entering the water is photographed by using the high-speed camera (2).

Images