Underwater explosion bubble water jet pressure field measuring system

Abstract

This application discloses an underwater explosive bubble water jet pressure field measurement system, relating to the field of water jet pressure field measurement technology. The system includes: a PVDF array pressure sensor, a data acquisition unit, and a host computer. The host computer generates a trigger signal and sends it to the data acquisition unit. The data acquisition unit generates two three-dimensional control signals based on the trigger signal, controlling the closing of one row and one column of analog switches in the switching module. This allows the acquisition module to collect the pressure generated by the underwater explosive bubble water jet through the sensing element and sends the pressure to the host computer. The host computer receives the pressure and processes it based on preset data processing logic. This application aims to solve the problem of poor measurement results in existing technologies when measuring the pressure field of explosive bubble water jets, achieving high-precision acquisition and analysis of microsecond-level water jet pressure fields.

Description

Technical Field

[0001] This application relates to the field of water jet pressure field measurement technology, and in particular to an underwater explosive bubble water jet pressure field measurement system. Background Technology

[0002] The study of underwater explosion bubble dynamics is of great value in fields such as ship protection, underwater blasting engineering, and explosion damage assessment. The physical field of the evolution process of water jet generated by the instability of underwater explosion bubbles is very complex. The high-pressure water jet generated at the moment of collapse during the arterial contraction phase is the main load source for inducing radioactive impact and structural damage.

[0003] Currently, it is difficult to accurately characterize the analytical solution through theoretical calculations, and numerical simulation and experimental methods are mainly used for research. Accurate measurement of the spatial pressure distribution field of instantaneously collapsing water jets is crucial for revealing the fluid-structure interaction mechanism and improving engineering protection design. However, there are currently a series of problems in measuring the spatial pressure distribution field of instantaneously collapsing water jets: For example, existing sensors have limitations: traditional piezoelectric ceramic sensors or piezoresistive sensors can withstand high pressure, but their frequency response range is insufficient to capture microsecond-level water jet pressure spikes; hydrophones have excellent high-frequency characteristics, but their range is insufficient and they are extremely prone to failure under the high pressure generated by underwater explosions and bubble collapses.

[0004] Furthermore, water jet loads are not uniform loads during their evolution. Existing single-point pressure sensors cannot effectively and comprehensively measure the changes in spatial non-uniform pressure over time, making it difficult to meet the measurement requirements of water jet loads.

[0005] For example, insufficient spatial resolution: existing measurements mostly rely on single-point or sparsely arranged sensors, which can only acquire local pressure field data and cannot obtain the full pressure field data when the bubble collapses.

[0006] For example, the integration level is low. Existing measurements mostly use separate instrument combinations (such as oscilloscope + independent sensor), which results in low integration level. Summary of the Invention

[0007] In response to the aforementioned problems and technical requirements, the applicant proposes an underwater explosive bubble water jet pressure field measurement system to solve the problem of poor measurement results in existing technologies when measuring the pressure field of explosive bubble water jets, and to achieve high-precision acquisition and analysis of microsecond-level water jet pressure fields.

[0008] This application provides an underwater explosive bubble water jet pressure field measurement system, the system comprising: PVDF array pressure sensor, data acquisition unit and host computer; The PVDF array pressure sensor comprises: a double-layer membrane with N*N sensitive elements formed by N rows and N columns of PVDF plates; wherein N is an integer greater than 1; wherein N columns are the upper PVDF membrane and N rows are the lower PVDF membrane; and it is connected to a data acquisition instrument via a coaxial cable and a BNC interface. The data acquisition unit includes a switching module and an acquisition module. The switching module includes two analog switch circuits, each containing N analog switches, which are respectively connected to the coaxial cables corresponding to the N rows and N columns of the PVDF array pressure sensor. The data acquisition unit communicates with the PVDF array pressure sensor and the host computer. The host computer is used to generate trigger signals and send them to the data acquisition instrument; The data acquisition instrument generates two three-dimensional control signals based on the trigger signal to control the closing of one row and one column of analog switches in the switching module, so as to acquire the pressure generated by the sensing element in the underwater exploding bubble water jet through the acquisition module and send the pressure to the host computer. The host computer receives the pressure and processes it based on preset data processing logic.

[0009] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, N equals 8; The row numbers of the row-oriented sensitive elements are predefined as A, B, C, D, E, F, G, H, and the column numbers of the column-oriented sensitive elements are predefined as a, b, c, d, e, f, g, h. Based on the principle of minimizing the single control quantity change of the analog switch, the change sequence of the control signal corresponding to the analog switch is determined, wherein the change sequence includes: 001-000-010-011-111-110-100-101. The data acquisition instrument controls the analog switch in a zigzag sequence based on the changing sequence of the trigger signal and the control signal.

[0010] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, the row direction of the PVDF array pressure sensor is connected to the input terminal of an analog switch circuit, and the column direction of the PVDF array pressure sensor is connected to the input terminal of another analog switch circuit. The output of one analog switch circuit is connected to the P terminal input of the acquisition module's acquisition circuit, and the output of another analog switch circuit is connected to the N terminal input of the acquisition module's acquisition circuit. The data acquisition device also includes: a main control unit; The host computer sends a trigger signal to the main control unit; The main control unit generates two three-dimensional control signals based on the trigger signal. At the same time, only one row and one column of analog switches are closed, and the electrical signal is input to the acquisition module. The acquisition module converts electrical signals into pressure and sends the converted pressure to the main control unit; The main control unit sends the pressure to the host computer.

[0011] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, the data acquisition instrument further includes: a power management module; The power management module splits the input DC power into two paths: one path powers the analog switching circuit, and the other path powers the main control unit.

[0012] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, the power management module divides the input DC power supply into two paths. One path generates ±20V voltage, and after passing through a linear regulator, it generates ±15V voltage to power the analog switching circuit. Another path generates an 18V power supply, which is then converted into a 5V voltage by a switching regulator to power the main control unit.

[0013] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, the acquisition module acquires the voltage values ​​of the row and column signals corresponding to the switching module relative to the ground, then calculates the relative voltage values ​​of the row signals and column signals using a differential method, and sends the calculation results to the host computer.

[0014] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, after the switching module completes one scanning cycle, it outputs a level flip signal.

[0015] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, the main control unit includes two components: one component is used to generate control signals, and the other component is used to receive trigger signals.

[0016] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, A, B, C, D, E, F, G, H and a, b, c, d, e, f, g, h are connected to the inner core of the coaxial cable through 16 enameled wires.

[0017] According to the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application, the host computer displays the waveform signal corresponding to each sensitive element based on the received pressure and performs cloud map drawing within a preset frame range.

[0018] The underwater exploding bubble water jet pressure field measurement system provided in this application includes: a PVDF array pressure sensor, a data acquisition unit, and a host computer. The PVDF array pressure sensor comprises a double-layer membrane with N*N sensitive elements formed by N rows and N columns of PVDF plates. The PVDF array sensor can accurately capture the microsecond-level water jet pressure at the moment of bubble collapse. The data acquisition unit includes a switching module and an acquisition module. The switching module includes two analog switch circuits, each containing N analog switches, which are respectively connected to the coaxial cables corresponding to the N rows and N columns of the PVDF array pressure sensor. The data acquisition unit generates two three-dimensional control signals based on the trigger signal transmitted from the host computer, controlling the closing of the analog switches in one row and one column of the switching module. This allows the acquisition module to collect the pressure generated by the underwater exploding bubble water jet by the sensitive elements, avoiding mutual interference caused by simultaneous changes in control signals and improving the accuracy of signal acquisition. The host computer receives the pressure and processes it based on preset data processing logic to achieve the purpose of acquiring, analyzing, and storing the pressure field, realizing high-precision acquisition and analysis of the microsecond-level water jet pressure field. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are 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 one of the structural schematic diagrams of the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application; Figure 2 This is the second schematic diagram of the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application; Figure 3 This is the third schematic diagram of the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application; Figure 4 This is the fourth schematic diagram of the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application; Figure 5 This is the fifth schematic diagram of the underwater explosion bubble water jet pressure field measurement system provided in the embodiments of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] This application provides an underwater explosion bubble water jet pressure field measurement system, such as... Figure 1 As shown, the system includes: a PVDF array pressure sensor 101, a data acquisition unit 102, and a host computer 103.

[0023] The PVDF array pressure sensor 101 includes: a double-layer membrane with N*N sensitive elements formed by N rows and N columns of PVDF plates, where N is an integer greater than 1.

[0024] In this diagram, column N represents the upper PVDF film, and row N represents the lower PVDF film; the data acquisition instrument is connected via a BNC interface connected to a coaxial cable.

[0025] The data acquisition unit 102 includes a switching module and an acquisition module.

[0026] The switching module includes two analog switch circuits, each containing N analog switches. The analog switch circuits are connected to the coaxial cables corresponding to the N rows and N columns of the PVDF array pressure sensor 101, respectively. The data acquisition unit 102 is connected to both the PVDF array pressure sensor and the host computer for communication.

[0027] The host computer 103 is used to generate a trigger signal and send the trigger signal to the data acquisition instrument 102.

[0028] The data acquisition unit 102 generates two three-dimensional control signals based on the trigger signal to control the closing of one row and one column of analog switches in the switching module, so as to acquire the pressure generated by the underwater explosion bubble water jet by the sensitive element through the acquisition module and send the pressure to the host computer 103.

[0029] The host computer 103 receives the pressure and processes it based on the preset data processing logic.

[0030] The underwater exploding bubble water jet pressure field measurement system provided in this application includes: a PVDF array pressure sensor, a data acquisition unit, and a host computer. The PVDF array pressure sensor comprises a double-layer membrane with N*N sensitive elements formed by N rows and N columns of PVDF plates. The PVDF array sensor can accurately capture the microsecond-level water jet pressure at the moment of bubble collapse. The data acquisition unit includes a switching module and an acquisition module. The switching module includes two analog switch circuits, each containing N analog switches, which are respectively connected to the coaxial cables corresponding to the N rows and N columns of the PVDF array pressure sensor. The data acquisition unit generates two three-dimensional control signals based on the trigger signal transmitted from the host computer, controlling the closing of the analog switches in one row and one column of the switching module. This allows the acquisition module to collect the pressure generated by the underwater exploding bubble water jet by the sensitive elements, avoiding mutual interference caused by simultaneous changes in control signals and improving the accuracy of signal acquisition. The host computer receives the pressure and processes it based on preset data processing logic to achieve the purpose of acquiring, analyzing, and storing the pressure field, realizing high-precision acquisition and analysis of the microsecond-level water jet pressure field.

[0031] In one specific embodiment, N equals 8.

[0032] The row numbers of the row-oriented sensitive elements are predefined as A, B, C, D, E, F, G, H, and the column numbers of the column-oriented sensitive elements are a, b, c, d, e, f, g, h.

[0033] like Figure 2 As shown, the structure of the PVDF array pressure sensor 101 is an array pressure sensor with 64 sensitive elements arranged in 8 rows and 8 columns.

[0034] Where ah represents the column sensing element of the PVDF array pressure sensor, and AH represents the row sensing element of the PVDF array pressure sensor. Each sensing element is a sensing capacitor. When pressure is applied to the sensing element, a proportional charge will be generated.

[0035] In this diagram, the red wire represents the signal output line on the upper surface of the PVDF, the blue wire represents the output line on the lower surface of the PVDF, and the black square represents the sensitive element of the PVDF array pressure sensor composed of rows and columns of sensitive elements.

[0036] When the red and blue wires of the corresponding sensitive element are simultaneously connected to the sampling circuit of the acquisition module, the acquired voltage is the pressure value generated by the corresponding sensitive element. The preferred design size of a single sensitive element in the PVDF array pressure sensor 101 is 5mm × 5mm, and the preferred spacing between sensitive element boundaries is 3mm. Therefore, the preferred total area of ​​the sensitive elements in the 8×8 array pressure sensor is 61mm × 61mm. Row or longitudinal sensitive elements are connected by wires no wider than 1.5mm. Row and longitudinal sensitive elements are not connected to each other. Each sensitive element is a capacitor formed by corresponding row and longitudinal sensitive elements.

[0037] The PVDF array pressure sensor 101 uses a PVDF film with a thickness of 30μm±5%, and the upper and lower surfaces are covered with conductive films. The entire sensor is encapsulated with polyimide. The row and column sensing elements are connected to the enameled wires at the corresponding edges of the PVDF film via gold-plated pads. The pad size is preferably 8mm×3mm, and all pads are on the front side of the PVDF film to facilitate the soldering of the enameled wires.

[0038] Specifically, using analog switches, only one row and one column are connected to the data acquisition instrument 102 at any given time. To avoid crosstalk caused by the simultaneous changes of multiple analog switch control signals, the order of changes in the control signals corresponding to the analog switches is determined based on the principle of minimizing the single change in the control quantity of the analog switches.

[0039] The sequence of changes includes: 001-000-010-011-111-110-100-101.

[0040] Specifically, the order of change is 001(2)-000(1)-010(3)-011(4)-111(8)-110(7)-100(5)-101(6)-001(2).

[0041] The values ​​in parentheses represent the input port numbers of the data acquisition instrument 102 corresponding to the analog switch.

[0042] Specifically, the data acquisition instrument 102 controls the analog switch in a zigzag sequence based on the change sequence of the trigger signal and the control signal. That is, based on the change process of the above control signal, it ensures that only one control bit changes at any given time for the two analog sensors (see the bold slanted text in Table 1, where the bold slanted text represents the changing control signal), and finally obtains a zigzag switching sequence corresponding to the change sequence of the PVDF array pressure sensor 101.

[0043]

[0044] Table 1. Change sequence of PVDF array pressure sensors Specifically, based on the transformation sequence in Table 1, the switching sequence corresponding to the PVDF array pressure sensor is a "zigzag" switching sequence, which can be found in [reference]. Figure 3 .

[0045] In this configuration, A~H and a~h are each connected to the inner core of the coaxial shielded cable via 16 enameled wires with a diameter of 0.2mm. The 0.2mm enameled wire was chosen to ensure strength while selecting the smallest possible wire diameter, facilitating the later installation of the PVDF array pressure sensor protective cover.

[0046] In one specific embodiment, the row direction of the PVDF array pressure sensor is connected to the input of an analog switch circuit, and the column direction of the PVDF array pressure sensor is connected to the input of another analog switch circuit. See also [link to specific details]. Figure 4 .

[0047] A~H are connected to the input terminals of high-speed analog switch 1, and a~h are connected to the input terminals of high-speed analog switch 2.

[0048] in, Figure 4 The high-speed analog switch in the diagram is the analog switch. High-speed analog switch 1 corresponds to one analog switch, OUT1 is the output of high-speed analog switch 1, high-speed analog switch 2 corresponds to another analog switch, OUT2 is the output of high-speed analog switch 2.

[0049] The output of one analog switch circuit is connected to the P terminal of the acquisition module's acquisition circuit, and the output of another analog switch circuit is connected to the N terminal of the acquisition module's acquisition circuit.

[0050] The host computer 103 sends a trigger signal to the main control unit; the main control unit generates two three-way control signals based on the trigger signal, and at the same time, only one row and one column of analog switches are closed, inputting the electrical signal into the acquisition module; the acquisition module converts the electrical signal into pressure and sends the converted pressure to the main control unit; the main control unit sends the pressure to the host computer.

[0051] Specifically, high-speed switching is key to enabling single-channel acquisition of multiple sensing elements in a PVDF array pressure sensor. When both output lines of a sensing element are simultaneously connected to the back-end acquisition instrument, an impact waveform will be acquired under impact pressure. Utilizing the characteristics of PVDF sensing elements, this application designs a switching module for a PVDF array pressure sensor based on a high-speed analog switch.

[0052] When the main control unit controls the analog switch, only one sensitive element's output is connected to the signal conditioning circuit at any given time.

[0053] Specifically, the ADG1208 chip can be selected as a high-speed analog switch chip, a single-chip iCMOS analog multiplexer with 8 built-in single channels. The ADG1208 switches one of the 8 inputs to a common output based on the address determined by the 3-bit binary address lines A0, A1, and A2 (control signals).

[0054] Among them, iCMOS devices can withstand dual power supply voltages of up to ±15V, while also improving performance, significantly reducing power consumption and minimizing package size.

[0055] The ADG1208 provides an EN input to enable or disable the device; when disabled, all channels are turned off. When the ADG1208 input is connected to the common output, each channel has the same conductivity in both directions, and the input signal range can be extended to the supply voltage range.

[0056] The ADG1208 uses a dual positive and negative power supply and has a high typical level transition time. The higher the voltage, the shorter the transition time. Under ±15V power supply conditions, the typical transition time is 80ns and the typical level duration is 240ns (accounting for 60% of the total cycle). Therefore, the limit switch switching frequency is converted to 1 / (80×2+240)=2.5MHz, which meets the 1.28MHz operating frequency requirement.

[0057] When operating at a switching frequency of 1.28MHz, the PVDF array pressure sensor containing 64 sensitive elements scans once in 50μs at a frequency of 20kHz, which meets the requirements for acquiring impact waveforms.

[0058] In one specific embodiment, the data acquisition device 102 further includes a power management module.

[0059] The power management module splits the input DC power into two paths: one path powers the analog switching circuit, and the other path powers the main control unit.

[0060] Specifically, the power management module divides the input DC power supply into two paths. One path generates ±20V and then ±15V after passing through a linear regulator to power the analog switching circuit. The other path generates 18V and then 5V after passing through a switching regulator to power the main control unit.

[0061] In one specific embodiment, the acquisition module acquires the voltage values ​​of the row and column signals corresponding to the switching module relative to ground, then calculates the relative voltage values ​​of the row signals and column signals using a differential method, and sends the calculation results to the host computer 103.

[0062] In one specific embodiment, after the switching module completes one scan cycle, it outputs a level toggle signal.

[0063] In one specific embodiment, the main control unit includes two components: one component is used to generate control signals, and the other component is used to receive trigger signals.

[0064] Specifically, based on the 1.28MHz switching frequency provided by the main control unit, 64 switching operations of 8 levels are obtained in one complete cycle. The order of level changes satisfies the logic in Table 2. The time required for 64 switching operations is 50μs. The scanning frequency of the PVDF array pressure sensor is 20kHz.

[0065] Furthermore, the switching frequency can be increased, for example to 2MHz. The time required for 64 switching is 32μs. The scanning frequency of the PVDF array pressure sensor is 31.25kHz. The order of level changes within one scanning cycle is also shown in Table 2.

[0066]

[0067] Table 28 Connection methods for voltage levels and switching modules Specifically, to eliminate the ground error generated by the PVDF array pressure sensor 101 after passing through the switching module, the data acquisition unit 102 adopts a differential input mode. That is, it separately acquires the voltage values ​​of the row and column signals relative to ground after passing through the switching module, and then uses a differential method to calculate the relative voltage values ​​of the row and column signals, which are then used as the signal output of the data acquisition card. Simultaneously, to ensure that the switching frequency of the switching module is consistent with the acquisition frequency, a level-to-together signal is output after the switching module completes one scan cycle.

[0068] The connection methods between the PVDF array pressure sensor and the data acquisition instrument are shown in Table 3:

[0069] Table 3. Connection methods between PVDF array pressure sensors and data acquisition instruments Specifically, the multi-channel data acquisition instrument has three channels, which are respectively connected to the switched row signal, the switched column signal, and the scan frame signal. To ensure the consistency of the sampling time of the three channels, an ADC chip with synchronous sampling mode needs to be selected. Based on the constraints of a sampling rate of not less than 1.28MHz, a sampling bit depth of not less than 14 bits, and a synchronous sampling channel depth of not less than 3, the AD7380-4 chip can be used as the sampling chip.

[0070] The AD7380-4 is a 16-bit, four-channel, synchronous sampling, high-speed, successive approximation register (SAR) analog-to-digital converter (ADC) operating from a 3.3V supply and achieving a maximum throughput of 4 MSPS. The differential analog inputs accept a wide common-mode input voltage, sampling and converting on the falling edge of the CS signal. The AD7380-4 features an on-chip oversampling module to improve dynamic range and reduce noise at lower bandwidths. Oversampling can improve resolution by up to two bits. The REFIN pin has a reference voltage range of 2.5V to 3.3V. Both the conversion and data acquisition processes utilize standard control inputs, enabling bidirectional interaction with microprocessors such as FPGAs. Conversion results can be output simultaneously in 4-wire mode for faster throughput, or in 1-wire serial mode when slower throughput is permissible. The device is compatible with 1.8V, 2.5V, and 3.3V interfaces when using independent logic power supplies. The AD7380-4 is packaged in an LFCSP and operates from -40°C to +125°C.

[0071] Specifically, before the acquired signal enters the ADC chip, it needs to pass through a signal matching circuit. The signal matching circuit uses two ADA4896-2 chips, which are unity-gain stable, low-noise, rail-to-rail output, high-speed voltage feedback amplifiers with a bandwidth of 230MHz and a wide operating voltage range (3V to 10V). They are particularly suitable for systems requiring high dynamic range, accuracy, and high speed. The operating temperature range is a wide industrial temperature range of -40℃ to +125℃.

[0072] Specifically, the main control unit uses two sets of ZYNQ7000 series minimum systems. One set is used to generate control signals (driving high-speed analog switches to switch at a frequency of 1.28MHz) and scan frame signals to ensure that the switching frequency and the acquisition frequency are consistent. The other set is used to control the high-speed data acquisition instrument, including data reading from the ADC chip, Ethernet interconnection, offline storage of the TF card, and control of external trigger signals.

[0073] The main control unit is a ZYNQ7000 series high-performance processor, based on an ARM Cortex-A9 core processor and FPGA architecture, with a maximum clock frequency of 667MHz. The Cortex-A9 processor integrates peripherals such as Ethernet, SDIO, and GPIO, enabling easy configuration of two main data interface circuits: TF cards and Ethernet interfaces, allowing for both online and offline data acquisition. The programmable logic side follows FPGA design methods, configuring six channels of high-speed switching signals to achieve high-speed analog switch switching (control signals, i.e., signal switching control at a preset frequency); and a four-channel 16-bit serial data transmission interface for high-speed data acquisition. The ARM side can control the FPGA section to acquire data via the AXI bus interface, storing the acquired data in a TF card or sending it to the host computer control software via Ethernet. The main control chip can receive external trigger signals; scanning and acquisition begin when the trigger signal is high and stop when it is low. The Ethernet interface simultaneously receives configuration parameters from the host computer control software, configuring the sampling rate, trigger mode, and input range.

[0074] Specifically, the power management module splits the input DC power supply into two paths. The first path generates ±20V, which is then regulated by a linear regulator to produce ±15V low-ripple power to power the analog switching circuit. The ±15V then passes through a linear regulator to produce ±10V low-ripple power to power the signal conditioning circuit. The second path generates 18V, which is then regulated by a switching regulator to produce 5V power to power the switching control FPGA, the acquisition control FPGA, and the ADC acquisition chip.

[0075] The power supply of the high-speed data acquisition instrument uses an input magnetic ring filter to reduce electromagnetic interference, and the analog ground and digital ground are isolated to avoid affecting the high-speed parallel data. The high-speed data acquisition instrument is equipped with a well-grounded shielded shell to reduce the impact of environmental noise on the signal acquisition of the PVDF array pressure sensor.

[0076] Due to the complex internal structure and numerous level conversions involved in the high-speed data acquisition unit, it is equipped with a full metal protective housing. The high-speed data acquisition unit has 16 BNC input interfaces, which connect to the 16 output pins of the PVDF array pressure sensor via a coaxial shielded cable, enabling high-speed switching of the sensing element. The output terminals of the high-speed data acquisition unit include digital I / O ports, a TF memory card port, a gigabit Ethernet communication port, indicator lights, an external trigger port, and a grounding terminal. The node terminals are connected to the metal protective housing to ensure equipotential bonding.

[0077] In one specific embodiment, the host computer 103 displays the waveform signal corresponding to each sensitive element based on the received pressure in a split-screen display, and performs cloud map drawing within a preset frame range.

[0078] Specifically, the host computer 103 can acquire signals from a PVDF array pressure sensor with 64 sensitive elements and configure the high-speed data acquisition instrument (data acquisition instrument).

[0079] Specifically, the connection between the data acquisition unit and the host computer includes: connecting a 24VDC power supply through the system's power terminal; connecting the "Ethernet" port of the high-speed data acquisition unit to the host computer's network port through the system's gigabit Ethernet; and connecting to the trigger port through the system's BNC cable. DIO4 and GND together form the trigger port. The system supports "software trigger," "rising edge trigger," and "high-level trigger," with a trigger level of 3.3V or 5V. The default level of the DIO4 trigger port is high, and a stable low level needs to be provided to DIO4 before the acquisition unit is powered on.

[0080] The host computer 103 drives the high-speed data acquisition instrument hardware to complete the acquisition of pressure values, generate intensity cloud maps, and store them as TDMS files, realizing the acquisition, analysis, and storage of raw sensor data. The main interface of the program is divided into three sub-pages via tabs: array sensor data acquisition, array sensor waveform display, and array sensor cloud map display and data export.

[0081] The array sensor data acquisition interface is used to acquire signals from the PVDF array pressure sensor via a high-speed data acquisition instrument. It can display the connection status of the high-speed data acquisition instrument, set the sampling rate, trigger mode, and sampling time of the high-speed data acquisition instrument, and display the acquired raw waveforms in real time. The array sensor waveform display interface can import the acquired raw data files. It can display the waveform information of 64 sensitive elements in a split screen, or display the waveform information of any sensitive element on the same display screen, and perform waveform zooming, panning, and other operations. The array sensor cloud map display and data export interface is used to draw cloud maps of PVDF array pressure sensor data within a specific frame range. The cloud map has an encrypted display function, and the cloud map data can be exported to text, Excel spreadsheets, MAT files, and other formats for further processing.

[0082] Specifically, when a user acquires data from a PVDF array pressure sensor, the software automatically creates a data storage folder named after the sampling time and stores all subsequently exported files and contour maps in this folder. Users can also analyze and display historical data without connecting to a high-speed data acquisition instrument, offering high interactivity. The host computer control software primarily uses a sequential structure, supplemented by event structures, conditional structures, and loop structures to implement the above functions. To ensure the integrity of the data sampled by the high-speed data acquisition instrument, the raw data files are stored using dedicated .tdms files for high-speed data acquisition.

[0083] Specifically, the pressure acquisition process of the measurement system in this application includes: (1) Open the host computer control software, click the “Connect” button, the software will execute the acquisition task and automatically jump to the “Array Sensor Data Acquisition” interface; if you click the “Do Not Connect” button, the software will directly enter the data processing task, and the historical data can be preprocessed. The software will automatically jump to the “Array Sensor Waveform Display” interface.

[0084] (2) The software will automatically start the connection task. The "Feedback Information" status bar will display "Connecting to the acquisition card..." and the "Acquisition device connection successful" status will be displayed in gray.

[0085] (3) After the high-speed data acquisition instrument is successfully connected, the "feedback information" status bar will display "Acquisition card connected successfully!" and the "Acquisition instrument connected successfully" status will be displayed in green. The "Start acquisition" button will change from gray to green. At this time, the high-speed data acquisition instrument is successfully initialized and can execute the content of (5).

[0086] (4) If the high-speed data acquisition device fails to connect, the "Feedback Information" status bar will display "Data acquisition card connection failed! Reconnect the data acquisition card..." and the "Data acquisition device connection failed" status will be displayed in red. At this time, it is necessary to check whether the high-speed data acquisition device is powered on normally, whether the gigabit network cable is connected securely, and whether the computer's IP address is set correctly. At this time, the high-speed data acquisition device is in the reconnection state until the connection is successful, and then the content of (3) can be executed.

[0087] (5) The sampling rate and switching rate of the high-speed data acquisition instrument are both fixed at 1280000 SPS. Before clicking the “Start Acquisition” button, the trigger mode and sampling time settings need to be completed. The trigger mode can be selected from five modes: “software trigger”, “external rising edge trigger”, “external falling edge trigger”, “external high level trigger”, and “external low level trigger”. The maximum sampling time can be set to 5000ms.

[0088] (6) Click the "Start Acquisition" button and wait for the waveform in the array sensor data acquisition interface to stop updating, indicating that one acquisition is complete. After the acquisition is complete, the circular light next to the "Start Acquisition" button will turn green. At the same time, the storage location of the raw data acquired in this acquisition will be displayed in the "File Storage Path" box.

[0089] (7) If you need to collect data again, click the “Start Collection” button. The specific operation is the same as (6).

[0090] (8) After the data acquisition is completed, click the “Close Data Acquisition” button. The host computer control software will exit the “Array Sensor Data Acquisition” interface and automatically jump to the “Array Sensor Waveform Display” interface.

[0091] Specifically, the data processing flow of the measurement system in this application includes: (11) If you enter the “Array Sensor Waveform Display” interface after the acquisition process ends, the raw data file of the last acquisition will be automatically linked in the “Read Raw Data” option box; if you select “Do not connect to high-speed data acquisition instrument” when the program starts, click the folder graphic button next to the “Read Raw Data” option box and select the historical data file to be processed in the pop-up dialog box.

[0092] (12) Click the “Draw Sensitive Element Waveform” button to display the voltage signal waveforms of 64 sensitive elements during the sampling time on the interface. The number in the upper left corner of the waveform is consistent with the sensitive element number of the PVDF array pressure sensor. The upper right corner of the interface can display information such as “maximum value”, “minimum value”, “total data length”, and “vertical extreme value” of the file read this time.

[0093] (13) By entering the corresponding numbers in the “Start Frame” and “End Frame” input boxes, the horizontal magnification and reduction of the voltage waveforms of 64 sensitive elements can be achieved, which can be used to observe the waveform changes within a specific sampling point range.

[0094] (14) Click the “Single Plot” button to display the waveform of any number of the 64 sensitive elements in the figure in the form of a single enlarged waveform; the button selection order is consistent with the sensitive element numbering of the PVDF array pressure sensor.

[0095] (15) Click the “Select All” button to display the voltage signals of all 64 sensitive elements in the figure; click the “Deselect All” button to cancel the display of voltage waveforms of all sensitive elements.

[0096] (16) Click the “X-axis” button on the interface, and scroll the mouse wheel in the waveform display area to zoom in or out of the waveform horizontally. At the same time, the numbers in the “start frame” and “end frame” input boxes will change accordingly, which is the current drawing range. Click the “zoom in” button and select the horizontal zoom button to zoom in on the waveform horizontally in the waveform display area. The same applies to the “Y-axis” button.

[0097] (17) After determining the waveform display area, the frame range displayed in the "Start Frame" and "End Frame" is the frame range for drawing the cloud map. Click the "Enter Cloud Map Interface" button, and the software will jump to the "Array Sensor Cloud Map Display and Data Export" interface.

[0098] (18) Click the "Draw Cloud Map" button to start drawing the cloud map. The "Cloud Map Intensity Range (V)" button can adjust the range of the cloud map intensity scale, and the "Cloud Map Update Rate (ms)" button can adjust the cloud map change rate. Enter the value and press Enter to confirm. The cloud map update rate setting range is 10-5000. The "Cloud Map Interpolation Number" tab can adjust the cloud map interpolation situation, which can be selected directly. Each generated frame image is stored in BMP format in the "YYYY_MM_DD-HH_MM_SS" folder in the "Measured Data" folder, where "YYYY_MM_DD-HH_MM_SS" represents "Year_Month_Day-Hour_Minute_Second". After completing the cloud map drawing, click the "End Drawing" button and wait for the number in the "Current Frame of Cloud Map" display box to stop changing.

[0099] (19) Select "Start and End Frame Export" in the "Export Data Range" tab, and click the "Export Data" button to export .txt (text), .xls (Excel), and .mat (Matlab) files. A dialog box will pop up saying "Data export complete, exit program!" The "Export File Path" display box shows the folder where the exported data is located.

[0100] (20) If you need to run the program again, you can directly click the button in the upper left corner of the interface to return to (12).

[0101] This application does not restrict or specify the content of the interface, but only describes the process.

[0102] pass Figure 5 The measurement system of this application is illustrated as follows: The PVDF array pressure sensor is connected to the signal conditioning circuit via an analog switching circuit.

[0103] The high-speed data acquisition unit (data acquisition unit) includes: analog switching circuit, signal conditioning circuit, analog-to-digital conversion circuit, and main control chip. The main control chip is connected to the host computer (host computer control software) via Ethernet through the ETH bus, and to the TF card via the SOIO bus.

[0104] This application achieves high-precision spatiotemporal capture and analysis of microsecond-level high-pressure water jet pressure fields through a PVDF array pressure sensor, a multi-channel high-speed data acquisition instrument, and a host computer. Specifically, it employs a flexible-packaged high-density PVDF array sensor, which combines a wide measurement bandwidth, MHz-level response frequency, and strong shock resistance, accurately capturing the microsecond-level water jet pressure peak at the moment of bubble collapse. The high-speed acquisition instrument uses an FPGA + multi-ADC chip cascade architecture, enabling high-speed analog switching and multi-channel high-speed data acquisition. Combined with a differential input mode, it eliminates the ground error generated by the PVDF array pressure sensor after passing through the switching module, meeting the phase fidelity error requirements of microsecond-level transient signals. The software in the host computer integrates a dynamic pressure field reconstruction algorithm, enabling the acquisition, analysis, and storage of raw sensor data. The system as a whole supports a closed-loop trigger-acquisition-analysis model for underwater exploding bubble water jet scenarios. Experimental data can directly drive fluid-structure coupling simulations, guiding engineering practices such as ship protection design and underwater explosion parameter optimization.

[0105] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0106] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0107] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A system for measuring the pressure field of an underwater exploding bubble water jet, characterized in that, The system includes: a PVDF array pressure sensor, a data acquisition unit, and a host computer; The PVDF array pressure sensor comprises: a double-layer membrane with N*N sensitive elements formed by N rows and N columns of PVDF plates; wherein N is an integer greater than 1; wherein N columns are the upper PVDF membrane and N rows are the lower PVDF membrane; and it is connected to a data acquisition instrument via a coaxial cable and a BNC interface. The data acquisition unit includes a switching module and an acquisition module. The switching module includes two analog switch circuits, each containing N analog switches, which are respectively connected to the coaxial cables corresponding to the N rows and N columns of the PVDF array pressure sensor. The data acquisition unit communicates with the PVDF array pressure sensor and the host computer. The host computer is used to generate trigger signals and send them to the data acquisition instrument; The data acquisition instrument generates two three-dimensional control signals based on the trigger signal to control the closing of one row and one column of analog switches in the switching module, so as to acquire the pressure generated by the sensing element in the underwater exploding bubble water jet through the acquisition module and send the pressure to the host computer. The host computer receives the pressure and processes it based on preset data processing logic.

2. The underwater explosion bubble water jet pressure field measurement system according to claim 1, characterized in that, The value of N is 8; The row numbers of the row-oriented sensitive elements are predefined as A, B, C, D, E, F, G, H, and the column numbers of the column-oriented sensitive elements are a, b, c, d, e, f, g, h. Based on the principle of minimizing the single control quantity change of the analog switch, the change sequence of the control signal corresponding to the analog switch is determined, wherein the change sequence includes: 001-000-010-011-111-110-100-101; The data acquisition instrument controls the analog switch in a zigzag sequence based on the changing sequence of the trigger signal and the control signal.

3. The underwater explosion bubble water jet pressure field measurement system according to claim 1 or 2, characterized in that, The row direction of the PVDF array pressure sensor is connected to the input of an analog switch circuit, and the column direction of the PVDF array pressure sensor is connected to the input of another analog switch circuit. The output of one analog switch circuit is connected to the P terminal input of the acquisition circuit of the acquisition module, and the output of another analog switch circuit is connected to the N terminal input of the acquisition circuit of the acquisition module. The data acquisition device also includes: a main control unit; The host computer sends a trigger signal to the main control unit; The main control unit generates two three-dimensional control signals based on the trigger signal. At the same time, only one row and one column of analog switches are closed, and the electrical signal is input to the acquisition module. The acquisition module converts electrical signals into pressure and sends the converted pressure to the main control unit; The main control unit sends the pressure to the host computer.

4. The underwater explosion bubble water jet pressure field measurement system according to claim 3, characterized in that, The data acquisition device also includes: a power management module; The power management module splits the input DC power into two paths: one path powers the analog switching circuit, and the other path powers the main control unit.

5. The underwater explosion bubble water jet pressure field measurement system according to claim 4, characterized in that, The power management module splits the input DC power into two paths. One path generates ±20V voltage, which is then converted into ±15V voltage by a linear regulator to power the analog switching circuit. Another path generates an 18V power supply, which is then converted into a 5V voltage by a switching regulator to power the main control unit.

6. The underwater explosion bubble water jet pressure field measurement system according to claim 1 or 2, characterized in that, The acquisition module acquires the voltage values ​​of the row and column signals corresponding to the switching module relative to ground, then calculates the relative voltage values ​​of the row and column signals using a differential method, and sends the calculation results to the host computer.

7. The underwater explosion bubble water jet pressure field measurement system according to claim 1 or 2, characterized in that, After the switching module completes one scan cycle, it outputs a level toggle signal.

8. The underwater explosion bubble water jet pressure field measurement system according to claim 3, characterized in that, The main control unit includes two components: one component is used to generate control signals, and the other component is used to receive trigger signals.

9. The underwater explosion bubble water jet pressure field measurement system according to claim 2, characterized in that, A, B, C, D, E, F, G, H and a, b, c, d, e, f, g, h are connected to the inner core of the coaxial cable through 16 enameled wires.

10. The underwater explosion bubble water jet pressure field measurement system according to claim 1 or 2, characterized in that, The host computer displays the waveform signal corresponding to each sensitive element based on the received pressure in a split-screen display, and performs cloud map drawing within a preset frame range.

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