High-pressure gas explosion test system in porous digital caustic experimental system

Abstract

This invention belongs to the field of explosion mechanics and experimental stress analysis technology, specifically disclosing a high-pressure gas explosion experimental system within a porous digital caustics experimental system. The system comprises four subsystems: high-pressure gas explosion generation, porous caustics optical measurement, data acquisition and processing, and integrated control and synchronous triggering. By using an FPGA module for real-time image segmentation and feature extraction to compress data, and by utilizing synchronous triggering to ensure precise synchronization of the explosion, illumination, and acquisition timelines, efficient, reliable, and automated observation and analysis of the transient physical field of the explosion is achieved. This system is not only suitable for studying standard explosion waves but can also be flexibly adapted to simulating complex turbulent fields and studying wave-system interactions, expanding the application boundaries and research value of porous digital caustics technology.

Description

Technical Field

[0001] This invention belongs to the field of explosion mechanics and experimental stress analysis technology, specifically relating to a high-pressure gas explosion test system in a porous digital caustics experimental system. Background Technology

[0002] In the fields of explosion mechanics and fluid dynamics, precise observation and quantitative analysis of transient and high-pressure physical phenomena are crucial for revealing their underlying mechanisms. Digital caustics experimental systems, as an advanced optical measurement technology, can non-contactly acquire key physical parameters such as the morphology of the explosion shock wave front and the pressure field distribution by recording and analyzing caustic spot images generated by changes in refractive index gradients in transparent media. This has made it an indispensable research tool in this field.

[0003] The porous digital caustics experimental system, by introducing a porous array structure, aims to achieve simultaneous observation of an explosion field over a larger spatial area or with higher spatial resolution, in order to capture multi-point detailed information about the explosion process. The basic principle of this system is to use a high-speed camera to record the evolution of caustic light spots passing through the porous plate, and then invert the dynamic physical quantities of the entire field.

[0004] In existing technologies, analyzing transient physical processes at the microsecond or even nanosecond level, such as explosion shock waves, requires high-speed imaging equipment with extremely high sampling rates. However, the extremely high sampling rate directly results in an enormous amount of image data generated in a single experiment, placing enormous pressure on data transmission bandwidth, data storage media, and subsequent image processing computing resources.

[0005] Meanwhile, the information acquisition efficiency of existing systems is limited by the physical bottlenecks of hardware performance. When pursuing higher temporal resolution and a larger spatial observation range, it is often difficult to achieve both simultaneously, hindering the improvement of effective information acquisition efficiency. Furthermore, for high-pressure gas explosion experiments, how to efficiently and reliably integrate the porous caustic optical system with experimental subsystems such as rapid high-pressure gas release, safety protection, and synchronous trigger control, while ensuring the stability and accuracy of optical measurements under extreme conditions, remains a challenge that has not yet been systematically addressed in existing technologies. Therefore, there is an urgent need for a high-pressure gas explosion experimental system capable of efficiently processing massive amounts of data, optimizing information acquisition efficiency, and achieving close coordination among all subsystems. Summary of the Invention

[0006] The purpose of this invention is to provide a high-pressure gas explosion test system in a multi-aperture digital caustic experimental system, so as to solve the technical contradictions in the prior art, such as the huge processing pressure caused by the massive data generated by high-speed imaging, the limitation of information acquisition efficiency by hardware bottlenecks, and the difficulty in integrating the multi-aperture caustic optical system with the high-pressure gas explosion test subsystem and the poor coordination.

[0007] This invention provides a high-pressure gas explosion test system in a porous digital caustics experimental system, comprising:

[0008] The high-pressure gas explosion generation subsystem is used to generate a controllable high-pressure gas explosion source, including a high-pressure gas chamber, a fast-release valve, an explosion cavity, a pressure sensor array, and a safety shield.

[0009] The porous caustic optical measurement subsystem is used for synchronous optical observation of the transient physical field generated by the explosion at multiple points in space. It includes an extended light source, a collimating lens group, a porous plate, an imaging lens group, and a high-speed image sensor.

[0010] The data acquisition and processing subsystem is used for efficient acquisition, compression and real-time analysis of observed images, including an image acquisition card, a field-programmable gate array preprocessing module and a host computer analysis unit;

[0011] The integrated control and synchronization triggering subsystem is used to coordinate the timing actions and safety interlocks of all subsystems, including the master control unit, distributed slave control units, and synchronization signal generator.

[0012] Preferably, the high-pressure air chamber is connected to the inlet of the quick-release valve via a high-pressure pipeline;

[0013] The outlet of the quick-release valve is rigidly connected to the air inlet of the explosion chamber;

[0014] The explosion cavity is a sealed container made of transparent material, with a pre-installed turbulence structure inside to form a specific flow field;

[0015] The pressure sensor array is embedded in the inner wall of the explosion cavity in a spatial grid pattern for multi-point monitoring of the pressure dynamics inside the cavity.

[0016] The safety shield covers the outside of the explosion cavity. It is made of high-strength transparent composite material and has a reserved window for light to pass through.

[0017] Preferably, the light emitted by the extended light source passes sequentially through the collimating lens group to form parallel light, and the parallel light passes perpendicularly through the explosion cavity and its internal transient flow field;

[0018] A beam carrying refractive index gradient information after passing through the flow field is incident on the porous plate; the porous plate is a planar array structure, and a micro-pore array arranged in a regular matrix is ​​etched on the porous plate, the diameter of each micro-pore is 50 micrometers to 200 micrometers, and the center distance between adjacent micro-pores is 3 to 5 times the pore diameter;

[0019] The multiple beams formed after passing through the porous plate are converged by the imaging lens group and form a corresponding multifocal speckle array image on the target surface of the high-speed image sensor.

[0020] Preferably, the image acquisition card is directly connected to the data output interface of the high-speed image sensor and is responsible for receiving the raw image data stream;

[0021] The field-programmable gate array preprocessing module is integrated inside the image acquisition card, and the image preprocessing logic is embedded inside it.

[0022] The host computer analysis unit is connected to the image acquisition card via a high-speed data bus and runs caustic image inversion analysis software.

[0023] Preferably, the main control unit is a human-computer interaction interface and a main logic controller;

[0024] The distributed slave control unit includes a pneumatic control unit, a light source control unit, and a camera control unit, which are respectively connected to the fast release valve, the extended light source, and the high-speed image sensor via a dedicated control bus.

[0025] The synchronization signal generator receives a trigger signal from the pressure sensor array or a manual trigger command from the main control unit, and generates multiple synchronization pulse signals with precise delay relationships, which are respectively sent to the fast release valve, the extended light source, and the high-speed image sensor to ensure strict timing synchronization between the explosion initiation, light source illumination, and image acquisition.

[0026] Preferably, the image preprocessing logic executed by the field-programmable gate array preprocessing module is as follows:

[0027] Real-time region segmentation and feature extraction are performed on the input high-speed image data stream;

[0028] The image preprocessing logic first uses the pre-stored spatial coordinate template of the multi-spot array to segment the image sub-region corresponding to each independent spot from each frame of the original image;

[0029] Next, an edge detection algorithm based on gray-level gradient is executed in parallel for each image sub-region to extract the contour pixel coordinate set of the caustic spot;

[0030] Finally, the contour coordinates of all extracted caustic spots and their corresponding timestamps are packaged to generate a compressed feature data package, which is then transmitted to the host computer analysis unit.

[0031] Preferably, the caustic image inversion analysis software running on the host computer analysis unit performs the following steps:

[0032] Receive feature data packets from the field-programmable gate array preprocessing module;

[0033] For the contour coordinate set of each caustic spot in the data packet, the caustic line equation based on geometric optics is applied for fitting to calculate the geometric characteristic parameters of the caustic spot, including the principal radius of curvature and the focal offset.

[0034] Based on the pre-calibrated mapping relationship between the refractive index of the medium and pressure and density, the geometric characteristic parameters are converted into pressure values ​​and density gradient values ​​at the corresponding spatial points.

[0035] Based on the spatial location calibration data of the porous plate, the physical quantities of all spatial points are reconstructed as the full-field pressure distribution cloud map and density gradient field of the explosion field at the corresponding time.

[0036] Preferably, the safety shield is equipped with an automatically opening and closing protective shutter at the reserved window.

[0037] The protective shutter is linked with the integrated control and synchronous triggering subsystem. The control logic is as follows: the protective shutter remains open from the time the system enters the preparatory state until the explosion test is completed; the protective shutter automatically closes within 100 milliseconds after the test is completed or when the system detects abnormal vibration.

[0038] Preferably, the multiple synchronization pulse signals generated by the synchronization signal generator have a programmable delay sequence; the delay sequence is defined as:

[0039] The first pulse triggers the opening of the rapid release valve, defined as the time zero point. ;

[0040] The second pulse is in The extended light source is triggered to reach the preset light intensity at any given time, and the first time change is... Pre-set according to gas filling pressure and valve characteristics;

[0041] The third pulse is in The high-speed image sensor is triggered to start acquiring data at a specific time, and the second time change is... The time it is expected to arrive at the observation area is set according to the shock wave, and the acquisition duration and frame rate of the high-speed image sensor are determined by the pulse width and frequency.

[0042] Preferably, the system operation mode includes a single trigger mode and a cyclic trigger mode;

[0043] In single-trigger mode, a single synchronization sequence executes a single explosion and data acquisition.

[0044] In the cyclic triggering mode, the integrated control and synchronization triggering subsystem automatically controls the high-pressure air chamber to refill after a single test, and restarts the synchronization sequence again after the pressure reaches the set value and the system status self-check passes, so as to realize unattended continuous repeated tests.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] 1. This invention solves the problems of data deluge, efficiency bottleneck and system coordination in high-pressure gas explosion porous caustics experiments by constructing a highly integrated and intelligent system-level solution.

[0047] 2. The system innovatively introduces a real-time image preprocessing module based on field-programmable gate array at the front end of the data acquisition link. The real-time image preprocessing module directly performs region segmentation and feature extraction on massive raw images through hardware logic, compresses the data volume, alleviates the pressure of data transmission and storage, and concentrates computing resources on the inversion of core physical quantities, thereby improving data processing efficiency.

[0048] 3. The system uses a precise integrated control and synchronous triggering subsystem to strictly synchronize the three key actions of rapid release of high-pressure gas, high-brightness light source illumination, and ultra-high-speed image acquisition with microsecond-level precision. An automatic safety protection mechanism is designed to ensure the stable operation of the optical measurement subsystem and the safety of personnel and equipment under extreme explosion conditions, achieving a high degree of automation and reliability in the test process.

[0049] 4. The system adopts a modular design, which allows for independent optimization of each subsystem, such as adjustable turbulence structure and low thermal deformation porous plate support. This makes the system not only suitable for standard explosion wave research, but also flexible enough to be adapted to cutting-edge scientific issues such as simulating complex turbulent fields and studying wave system interactions, thus expanding the application boundaries and scientific research value of porous digital caustics technology. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the overall technical solution architecture of the present invention;

[0051] Figure 2 This is a schematic diagram of the core principle framework of real-time image preprocessing and data compression based on field-programmable gate array in this invention;

[0052] Figure 3 This is a diagram of the precise synchronous control logic framework between the high-pressure gas explosion, optical measurement, and data acquisition in this invention.

[0053] Figure 4 This is a flowchart illustrating the reconstruction logic of the present invention, which involves the inversion of physical quantities of a full-field explosion from multifocal speckle image features.

[0054] Figure 5 This is a schematic diagram illustrating the multi-level interaction relationship between the modular design and secure collaborative operation of the system in this invention. Detailed Implementation

[0055] Example 1: Refer to Appendix Figure 1 To be continued Figure 5 The high-pressure gas explosion test system in the multi-aperture digital caustics experimental system proposed in this invention is an integrated experimental platform for high-precision and high-efficiency optical diagnostics of extreme transient physical fields. This system achieves closed-loop control across the entire chain, from explosion source generation, light field modulation, image acquisition to physical quantity inversion, by deeply coupling the high-pressure gas explosion generation subsystem, the multi-aperture caustics optical measurement subsystem, the data acquisition and processing subsystem, and the integrated control and synchronous triggering subsystem.

[0056] Please refer to the attached document. Figure 1 , attached Figure 1 The overall technical architecture of the present invention is shown. The subsystems are closely coordinated through a high-speed communication bus and a synchronization signal network to form an intelligent experimental system with self-sensing, self-decision-making and self-protection capabilities.

[0057] The high-pressure gas explosion generation subsystem is the energy and disturbance source of the entire experimental system. Its core function is to controllably generate high-pressure gas explosion events with specific initial conditions. This subsystem includes a high-pressure chamber, a rapid release valve, an explosion cavity, a pressure sensor array, and a safety shield. The high-pressure chamber is a seamless steel container with a pressure resistance of not less than 50 MPa and an internal volume of 2 to 10 liters, used to store compressed air, nitrogen, or a mixture of combustible gases.

[0058] The high-pressure chamber is rigidly connected to the inlet of the quick-release valve via a 6 mm inner diameter stainless steel high-pressure pipeline. A metal sealing ring is used at the connection to ensure no leakage under high pressure. The quick-release valve is an electromagnetically driven high-speed valve with an opening response time of less than 1 millisecond and a maximum diameter of 12 mm. It can release high-pressure gas from the high-pressure chamber to the explosion cavity within microseconds, thus creating a steep pressure front.

[0059] The explosion chamber is a cylindrical sealed container made of high-strength optical glass or fused silica, with an inner diameter of 300 mm, a height of 400 mm, and a wall thickness of 20 mm. It can withstand internal instantaneous pressure peaks of up to 10 MPa without rupturing.

[0060] The explosion cavity is pre-installed with a turbulence structure to form a specific flow field. This turbulence structure consists of multiple layers of staggered perforated plates with an opening ratio of 30% to 70%. The spacing between adjacent perforated plates can be manually adjusted within the range of 10 mm to 50 mm to simulate turbulence structures at different scales.

[0061] The pressure sensor array is embedded in the inner wall of the explosion cavity in the form of a spatial grid. A total of 16 miniature piezoelectric pressure sensors are arranged, each with a range of 0 to 20 MPa, a response frequency of not less than 1 MHz, and a sampling interval of 25 mm. It is used to monitor the dynamic evolution of pressure at multiple points in the cavity in real time during the explosion.

[0062] The safety shield covers the outside of the explosion cavity. It is made of high-strength transparent composite material and consists of three layers: the outer layer is a 5 mm thick explosion-proof polycarbonate plate, the middle layer is a 3 mm thick tempered glass, and the inner layer is a 2 mm thick flexible energy-absorbing film.

[0063] The safety shield is designed with four symmetrically distributed reserved windows for optical measurement beams to pass perpendicularly through the explosion cavity. The edges of the windows are precision polished to reduce light scattering. An automatically opening and closing protective shutter is installed at each of the reserved windows. This shutter is controlled by an electromagnetic drive mechanism, and its control logic is linked to the integrated control and synchronous triggering subsystem.

[0064] Once the system enters the ready state, the main control unit sends an opening command to the shutter driver, and the shutter opens fully within 200 milliseconds;

[0065] Within 100 milliseconds after the explosion test is completed, or when the system detects an abnormal vibration signal (such as acceleration greater than 5g), the shutter immediately closes, effectively preventing debris from flying and causing damage to optical equipment and personnel in the event of accidental cavity rupture.

[0066] The porous caustic optical measurement subsystem is the core sensing unit of this invention. Its function is to perform non-contact, full-field, high spatiotemporal resolution optical observation of the transient refractive index gradient field generated by the explosion. This porous caustic optical measurement subsystem includes an extended light source, a collimating lens group, a porous plate, an imaging lens group, and a high-speed image sensor.

[0067] The extended light source is a high-brightness pulsed xenon lamp or laser diode array with a light-emitting area of ​​not less than 50 mm × 50 mm, an adjustable pulse width range of 1 microsecond to 100 microseconds, and a peak light intensity of not less than 106 candela per square meter, ensuring that an image with a sufficient signal-to-noise ratio is obtained in an extremely short exposure time.

[0068] The light emitted from the extended light source first passes through a collimating lens group, which consists of two achromatic cemented doublet lenses with focal lengths of 100 mm and 200 mm, respectively. This collimating lens group is used to convert the diverging beam into a collimated beam with parallelism better than 0.1 milliradians. This collimated beam passes perpendicularly through the explosion cavity and its internal transient flow field. Due to the drastic change in gas density caused by the explosion wave, a local refractive index gradient is generated, causing the beam to deflect during propagation.

[0069] The outgoing beam carrying refractive index gradient information is then incident on the porous plate. The porous plate is a planar array structure, and its substrate material is microcrystalline glass with a thermal expansion coefficient of less than 1×10⁻⁶ / degree Celsius, with a thickness of 2 mm. The surface is ultra-precision polished, and its flatness is better than... ( nanometer).

[0070] The porous plate is etched with a regular matrix array of micropores, with an array size of 64×64. The diameter of each micropore is 50 micrometers to 200 micrometers, and the center distance between adjacent micropores is 3 to 5 times the diameter of the pore, i.e., 150 micrometers to 1000 micrometers, in order to avoid crosstalk between sub-beams.

[0071] The porous plate is mounted on the vibration isolation optical platform via a three-point flexible support structure. This three-point flexible support structure consists of three symmetrically distributed flexible hinges, each made of beryllium copper alloy. This allows the porous plate to undergo minute in-plane deformation when heated or stressed, thus avoiding out-of-plane warping and ensuring that the flatness change of the micropore array is less than 1 micrometer throughout the entire experiment.

[0072] The 64×64 sub-beams formed after passing through the perforated plate are converged by an imaging lens group consisting of three high numerical aperture objectives with a total magnification of 1x and a working distance of 300 mm, ensuring that all sub-beams are clearly imaged on the target surface of the high-speed image sensor.

[0073] The high-speed image sensor is a back-illuminated CMOS sensor with a resolution of 2048×2048 pixels, a pixel size of 11 micrometers×11 micrometers, a maximum frame rate of 1 million frames per second, a dynamic range of no less than 12 bits, and can continuously acquire 1024 frames of images in single-trigger mode, with each frame containing 8 megabytes of data.

[0074] The data acquisition and processing subsystem is responsible for the efficient acquisition, real-time compression, and intelligent analysis of the raw data stream output by the high-speed image sensor. It is a key module for overcoming the bottleneck of massive data processing. The data acquisition and processing subsystem includes an image acquisition card, a field-programmable gate array (FPGA) preprocessing module, and a host computer analysis unit.

[0075] The image acquisition card is a high-speed acquisition device with a PCIe 4.0 interface, supporting CameraLink HS or CoaX Press 2.0 protocols. It boasts a maximum data throughput bandwidth of 25 gigabits per second and connects directly to the data output interface of a high-speed image sensor, ensuring frame-free transmission. The field-programmable gate array (FPGA) preprocessing module is integrated within the image acquisition card, utilizing Xilinx Ultrascale+ series chips with no fewer than 1 million logic units and dedicated image preprocessing logic.

[0076] Please refer to the attached document. Figure 2, attached Figure 2 This paper demonstrates the core principle framework of real-time image preprocessing and data compression based on field-programmable gate arrays (FPGAs). First, a pre-stored spatial coordinate template for a multi-foc speckle array is used. This template, obtained through static optical calibration during the system calibration phase, contains the center position of each speckle in the image coordinate system. and effective radius — Divide each original image frame into 64×64 independent image sub-regions, each sub-region being 64×64 pixels in size.

[0077] Next, a gray-level gradient-based edge detection algorithm is executed in parallel for each image sub-region. This edge detection algorithm extracts the contour pixel coordinate set of the caustic spot by calculating the magnitude and direction of the local pixel gradient. .

[0078] Finally, the contour coordinates of all 64×64 caustic spots, their corresponding timestamps, and system status flags are packaged to generate a compressed feature data packet. This feature data packet is less than 5% the size of the original image; for example, for an 8-megabyte original image, the feature data packet is typically no larger than 400 kilobytes.

[0079] The host computer analysis unit is a workstation equipped with dual Intel Xeon processors, 256 gigabytes of memory, and an NVIDIA A100 GPU. It is connected to the image acquisition card via a PCIe x16 bus and runs caustic image inversion analysis software. After receiving feature data packets, the software performs a physical quantity reconstruction process.

[0080] Please refer to the attached document. Figure 4 The appendix Figure 4 This paper demonstrates the reconstruction logic from multi-focal speckle image features to the inversion of full-field explosion physics quantities. Specifically, the software applies a caustic line equation based on geometric optics to fit the contour coordinate set of each caustic speckle, calculating the geometric feature parameters of that caustic speckle, including the principal radius of curvature. and focus offset The equation for caustics can be expressed as:

[0081] ;

[0082] denoted as the refractive index of the medium. The x-axis is... The vertical axis represents the coordinates. This is based on a pre-defined mapping relationship between the medium's refractive index and pressure / density—a relationship established using the Gladstone-Dale formula, i.e. , It is the Gladstone-Dale constant. For gas density, and density And pressure Using the ideal gas law Correlation—converting geometric feature parameters into pressure values ​​at corresponding spatial points. With density gradient value . It is the thermodynamic temperature.

[0083] By combining the spatial position calibration data of the porous plate (i.e., the three-dimensional coordinates of each micropore in the world coordinate system), the physical quantities of all spatial points are reconstructed into the full-field pressure distribution cloud map and density gradient vector field of the explosion field at the corresponding time through cubic spline interpolation or radial basis function interpolation methods. The spatial resolution reaches the order of 1 millimeter and the temporal resolution reaches the order of 1 microsecond.

[0084] The integrated control and synchronization triggering subsystem is the "central nervous system" of the entire system, responsible for coordinating the timing actions, status monitoring, and safety interlocks of all subsystems. The integrated control and synchronization triggering subsystem includes a master control unit, distributed slave control units, and a synchronization signal generator. The master control unit is the human-machine interface and overall logic controller, running on an industrial-grade touchscreen computer. It provides a graphical user interface, allowing users to set parameters such as explosion pressure, light source pulse width, camera frame rate, and acquisition delay, and displays system status, sensor readings, and safety alarms in real time.

[0085] Reference Appendix Figure 5 , attached Figure 5 The demonstration showcased a distributed slave control unit comprising a pneumatic control unit, a light source control unit, and a camera control unit, connected to a quick-release valve, an extended light source, and a high-speed image sensor via RS-485 or CAN bus, respectively. The pneumatic control unit incorporates a proportional pressure reducing valve and a pressure feedback loop, enabling precise control of the high-pressure chamber's inflation pressure to an accuracy of ±0.1 MPa. The light source control unit provides programmable current drive, ensuring the light source reaches a preset light intensity at a specified time. The camera control unit configures the camera's exposure time, gain, and trigger mode. A synchronization signal generator serves as the core timing engine, receiving input signals including threshold trigger signals from the pressure sensor array (automatically triggered when the pressure at a certain point exceeds a set threshold) or manual trigger commands from the master control unit.

[0086] Please refer to the attached document. Figure 3 , attached Figure 3 This demonstrates the precise synchronization control logic between the high-pressure gas explosion, optical measurement, and data acquisition. A synchronization signal generator produces three TTL-level synchronization pulse signals with precise time delay relationships:

[0087] The first pulse is at time zero. Triggers the opening of the rapid release valve;

[0088] The second pulse is in The first time change is triggered by the extended light source. The values ​​are preset using a lookup table based on the gas filling pressure and valve opening characteristics, with typical values ​​ranging from 0.5 milliseconds to 5 milliseconds.

[0089] The third pulse is in The high-speed image sensor is triggered to start acquiring data at a specific time, and the second time change is recorded. The time set according to the expected arrival time of the shock wave in the observation area is typically 1 to 10 milliseconds, and the pulse width determines the acquisition duration, while the frequency determines the frame rate.

[0090] All delay parameters are set with an accuracy better than 1 microsecond, ensuring strict synchronization between explosion initiation, light source illumination, and image acquisition. In addition, the system has a multi-level safety interlock mechanism: when any pressure sensor reading is abnormal, the shutter is not opened, the cooling system malfunctions, or vibration exceeds the limit, the main control unit immediately stops the synchronization sequence and initiates an emergency depressurization procedure.

[0091] The system operates in two modes: single-trigger mode and cyclic trigger mode. In single-trigger mode, the operator sets parameters through the human-machine interface and clicks the "Start Test" button. The system then executes a complete synchronization sequence, completing a single explosion and data acquisition.

[0092] In cyclic triggering mode, the integrated control and synchronization triggering subsystem automatically executes subsequent procedures after a single test: first, the quick-release valve is closed, the vacuum pump is started to evacuate the explosion chamber to below 10 kPa, then the high-pressure gas chamber is refilled to the set pressure, and all sensors and actuators undergo self-checks. Once the pressure stabilizes and the system status self-check passes, the system automatically restarts the synchronization sequence, enabling unattended, continuous, and repeated tests. Parameters for each test (such as inflation pressure, spoiler spacing, and light source intensity) can be set independently, facilitating parametric studies. The entire cycle can be as short as 30 seconds, improving experimental efficiency.

[0093] The system of this invention exhibits superior performance in actual operation. In a typical experiment, the high-pressure chamber was filled with 5 MPa compressed air, and the turbulence structure was set as a three-layer perforated plate with an opening ratio of 50% and a spacing of 30 mm. The synchronization signal generator was set... millisecond, Milliseconds: A high-speed image sensor acquires 200 frames of images at a frame rate of 500,000 frames per second. The field-programmable gate array (FPGA) preprocessing module successfully compresses each 8-megabyte raw image frame into a 380-kilobyte feature data packet, achieving a data compression ratio of 95.25%.

[0094] Within 5 seconds of data acquisition, the host computer analysis unit reconstructed the full-field pressure cloud map, clearly showing the diffraction, reflection, and focusing phenomena of the explosion wave behind the turbulent structure, verifying the system's effectiveness in diagnosing complex flow fields. The shutter of the safety shield reliably closed within 80 milliseconds after the test, without any safety incidents.

[0095] In summary, this embodiment constructs an efficient, reliable, and intelligent high-pressure gas explosion porous caustics experimental platform through highly integrated subsystem design, front-end hardware-level data compression, microsecond-level synchronous control, and multiple safety mechanisms, providing a powerful tool for interdisciplinary research in transient fluid mechanics, explosion mechanics, and optical diagnostic technology.

[0096] Example 2: Based on Example 1, this example is adaptively optimized for explosion scenarios with higher energy densities. The key improvements are to the energy release mechanism of the high-pressure gas explosion generation subsystem and the anti-interference capability of the porous caustic optical measurement subsystem. This example is suitable for studying extreme conditions such as the combustion-to-detonation process of combustible gases or the interaction of shock waves driven by high-energy explosives.

[0097] In this embodiment, the high-pressure gas explosion generation subsystem incorporates a dual-chamber premixing structure. Specifically, the explosion chamber is divided into an upstream premixing chamber and a downstream main explosion chamber, connected by an adjustable throat. The premixing chamber is used to premix fuel gases (such as hydrogen or methane) and oxidizers (such as oxygen or air), with the mixing ratio precisely controlled by a mass flow controller, ranging from 80% to 120% of the stoichiometric ratio. The main explosion chamber remains empty or is filled with inert gas.

[0098] The quick-release valve has been replaced with a high-speed rotary valve or a rupture diaphragm, and its opening mechanism has been changed from electrical signal triggering to pressure wave triggering to achieve a steeper pressure rise. The pressure sensor array has been upgraded to a fiber Bragg grating sensor array, which has stronger anti-electromagnetic interference capabilities and is suitable for detonation environments with strong electromagnetic pulses. The safety shield has been enhanced with a five-layer composite structure, with an outer layer of 10 mm thick bulletproof ceramic plate and an inner layer of metal mesh to withstand high-speed fragment impacts. The protective shutter's drive mechanism has been changed to hydraulic drive, reducing the closing time to less than 50 milliseconds.

[0099] In this embodiment, the porous caustic optical measurement subsystem employs dual-wavelength differential technology to suppress background radiation interference. The extended light source has been upgraded from a single-wavelength source to two independent pulsed lasers with wavelengths of 532 nm and 635 nm, emitting alternately. A beam-splitting prism and a dual-channel imaging lens group are added behind the porous plate to image the sub-beams of different wavelengths onto two high-speed image sensors respectively.

[0100] Because the high-temperature field of an explosion generates strong blackbody radiation with a spectral distribution independent of the laser wavelength, while the caustic signal is wavelength-dependent, differential processing can effectively separate the real caustic signal from background noise. The field-programmable gate array (FPGA) preprocessing module correspondingly adds dual-channel data fusion logic, first extracting features from the two channels separately, and then synthesizing the final caustic spot contour using weighted averaging or principal component analysis.

[0101] In this embodiment, the data acquisition and processing subsystem enhances real-time inversion capabilities. The host computer analysis unit deploys a lightweight neural network model, trained offline using extensive simulation data. This model directly predicts local pressure gradients from caustic spot contours, avoiding complex geometric-optical fitting processes and reducing single-frame inversion time from 5 seconds to 200 milliseconds. The lightweight neural network model takes as input a set of 64×64 caustic spot contour coordinates and outputs the pressure gradient tensor of the corresponding spatial points.

[0102] The integrated control and synchronization triggering subsystem adds multi-level triggering logic. The synchronization signal generator not only responds to pressure thresholds but also to temperature, light intensity, or ion current signals, enabling multi-physics field joint triggering. For example, when the ion probe detects that the flame front has reached a preset position, the synchronization sequence is immediately initiated to ensure data capture during the critical stage of detonation transition.

[0103] This embodiment was successfully applied in a hydrogen-air mixture detonation experiment. The system ignited the mixture at an initial pressure of 20 kPa and successfully captured the lattice structure evolution during the transition from combustion to detonation, achieving a spatial resolution of 0.5 mm and a temporal resolution of 500 nanoseconds. The dual-wavelength differential technique improved the signal-to-noise ratio by three times, and the correlation coefficient between the neural network inversion results and traditional methods reached 0.98, verifying the superior performance of this embodiment under extreme conditions.

[0104] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0105] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-pressure gas explosion test system in a multi-hole digital caustic experimental system, characterized in that, include: The high-pressure gas explosion generation subsystem is used to generate a controllable high-pressure gas explosion source, including a high-pressure gas chamber, a fast-release valve, an explosion cavity, a pressure sensor array, and a safety shield. The porous caustic optical measurement subsystem is used for synchronous optical observation of the transient physical field generated by the explosion at multiple points in space. It includes an extended light source, a collimating lens group, a porous plate, an imaging lens group, and a high-speed image sensor. The data acquisition and processing subsystem is used for efficient acquisition, compression and real-time analysis of observed images, including an image acquisition card, a field-programmable gate array preprocessing module and a host computer analysis unit; An integrated control and synchronization triggering subsystem is used to coordinate the timing actions and safety interlocks of all subsystems, including a master control unit, distributed slave control units, and a synchronization signal generator; The light emitted by the extended light source passes sequentially through the collimating lens group to form parallel light, and the parallel light passes perpendicularly through the explosion cavity and its internal transient flow field; A beam carrying refractive index gradient information after passing through the flow field is incident on the porous plate; the porous plate is a planar array structure, and a micro-pore array arranged in a regular matrix is ​​etched on the porous plate, the diameter of each micro-pore is 50 micrometers to 200 micrometers, and the center distance between adjacent micro-pores is 3 to 5 times the pore diameter; The multiple sub-beams formed after passing through the perforated plate are converged by the imaging lens group and form a corresponding multifocal speckle array image on the target surface of the high-speed image sensor; The image preprocessing logic executed by the field-programmable gate array (FPGA) preprocessing module is as follows: Real-time region segmentation and feature extraction are performed on the input high-speed image data stream; The image preprocessing logic first uses the pre-stored spatial coordinate template of the multi-spot array to segment the image sub-region corresponding to each independent spot from each frame of the original image; Next, an edge detection algorithm based on gray-level gradient is executed in parallel for each image sub-region to extract the contour pixel coordinate set of the caustic spot; Finally, the contour coordinates of all extracted caustic spots and their corresponding timestamps are packaged to generate a compressed feature data package, which is then transmitted to the host computer analysis unit.

2. The high-pressure gas explosion test system in the porous digital caustic experimental system according to claim 1, characterized in that, The high-pressure air chamber is connected to the inlet of the quick-release valve via a high-pressure pipeline; The outlet of the quick-release valve is rigidly connected to the air inlet of the explosion chamber; The explosion cavity is a sealed container made of transparent material, with a pre-installed turbulence structure inside to form a specific flow field; The pressure sensor array is embedded in the inner wall of the explosion cavity in a spatial grid pattern for multi-point monitoring of the pressure dynamics inside the cavity. The safety shield covers the outside of the explosion cavity. It is made of high-strength transparent composite material and has a reserved window for light to pass through.

3. The high-pressure gas explosion test system in the porous digital caustic experimental system according to claim 1, characterized in that, The image acquisition card is directly connected to the data output interface of the high-speed image sensor and is responsible for receiving the raw image data stream. The field-programmable gate array preprocessing module is integrated inside the image acquisition card, and the image preprocessing logic is embedded inside it. The host computer analysis unit is connected to the image acquisition card via a high-speed data bus and runs caustic image inversion analysis software.

4. The high-pressure gas explosion test system in the porous digital caustic experimental system according to claim 1, characterized in that, The main control unit is a human-computer interaction interface and a main logic controller; The distributed slave control unit includes a pneumatic control unit, a light source control unit, and a camera control unit, which are respectively connected to the fast release valve, the extended light source, and the high-speed image sensor via a dedicated control bus. The synchronization signal generator receives a trigger signal from the pressure sensor array or a manual trigger command from the main control unit, and generates multiple synchronization pulse signals with precise delay relationships, which are respectively sent to the fast release valve, the extended light source, and the high-speed image sensor to ensure strict timing synchronization between the explosion initiation, light source illumination, and image acquisition.

5. The high-pressure gas explosion test system in the porous digital caustic experimental system according to claim 1, characterized in that, The caustic image inversion analysis software running in the host computer analysis unit performs the following steps: Receive feature data packets from the field-programmable gate array preprocessing module; For the contour coordinate set of each caustic spot in the data packet, the caustic line equation based on geometric optics is applied for fitting to calculate the geometric characteristic parameters of the caustic spot, including the principal radius of curvature and the focal offset. Based on the pre-calibrated mapping relationship between the refractive index of the medium and pressure and density, the geometric characteristic parameters are converted into pressure values ​​and density gradient values ​​at the corresponding spatial points. Based on the spatial location calibration data of the porous plate, the physical quantities of all spatial points are reconstructed as the full-field pressure distribution cloud map and density gradient field of the explosion field at the corresponding time.

6. The high-pressure gas explosion test system in the porous digital caustic experimental system according to claim 1, characterized in that, The safety shield is equipped with an automatically opening and closing protective shutter at the reserved window. The protective shutter is linked with the integrated control and synchronous triggering subsystem. The control logic is as follows: the protective shutter remains open from the time the system enters the preparatory state until the explosion test is completed; the protective shutter automatically closes within 100 milliseconds after the test is completed or when the system detects abnormal vibration.

7. The high-pressure gas explosion test system in the porous digital caustic experimental system according to claim 1, characterized in that, The synchronization signal generator generates multiple synchronization pulse signals with programmable delay sequences; these delay sequences are defined as follows: The first pulse triggers the opening of the rapid release valve, defined as the time zero point. ; The second pulse is in The extended light source is triggered to reach the preset light intensity at any given time, and the first time change is... Pre-set according to gas filling pressure and valve characteristics; The third pulse is in The high-speed image sensor is triggered to start acquiring data at a specific time, and the second time change is... The time it is expected to arrive at the observation area is set according to the shock wave, and the acquisition duration and frame rate of the high-speed image sensor are determined by the pulse width and frequency.

8. The high-pressure gas explosion test system in the porous digital caustic experimental system according to claim 1, characterized in that, The system operation modes include single-trigger mode and cyclic trigger mode; In single-trigger mode, a single synchronization sequence executes a single explosion and data acquisition. In the cyclic triggering mode, the integrated control and synchronization triggering subsystem automatically controls the high-pressure air chamber to refill after a single test, and restarts the synchronization sequence again after the pressure reaches the set value and the system status self-check passes, so as to realize unattended continuous repeated tests.

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