Ultrahigh-pressure safe light-transmitting environment box for calibration of laser cavitation underwater pressure sensor

Abstract

The invention discloses an ultrahigh-pressure safe light-transmitting environment box for calibration of a laser cavitation underwater pressure sensor. The device comprises a pressure-bearing box body, a cylindrical inner cavity is formed by processing a metal matrix, and the cylindrical inner cavity is used for containing a liquid medium required by calibration and bearing an ultrahigh pressure environment; the visual observation channel comprises a plurality of observation openings, each observation opening adopts a conical surface transition structure, the inner wall of the box body is a large-end round hole, the inner wall of the box body is shrunk towards the outer side of the box body to form a small-end round hole, and threads are formed in the inner wall of the box body; and the pressure sensor mounting port is arranged on the surface of the pressure-bearing box body. Through collaborative design of a composite pressure bearing structure, a sealing mechanism and an intelligent safety system, optical monitoring and safety control in an ultrahigh pressure environment are realized through structure innovation and function integration, and the technical problem that optical visualization and equipment reliability are difficult to consider in a high pressure environment is solved.

Description

Technical Field

[0001] This invention belongs to the technical field of high-pressure experimental equipment, specifically to a light-transmitting experimental chamber structure suitable for simulating ultra-high pressure environments up to 100 MPa. This chamber is particularly useful for dynamic calibration systems of underwater pressure sensors based on laser-induced cavitation, but can also be expanded to other applications requiring optical observation, such as high-pressure material performance testing. Background Art

[0002] In the field of national strategic equipment research and development, there is a large demand for microsecond-level dynamic pressure measurement in liquid environments. To ensure the accuracy and reliability of underwater pressure sensor measurement data, pressure sensors need to be calibrated regularly. However, the commonly used verification procedures all calibrate pressure sensors in an atmospheric environment. To this end, researchers have proposed an improved solution. This solution uses a high-pressure environmental chamber combined with laser-induced cavitation bubbles to generate pressure waves as a dynamic calibration excitation source. The shock waves during the cavitation collapse process are used to simulate the in-situ ambient pressure, thereby calibrating the sensor to be calibrated.

[0003] The high-pressure sealed test chamber, the core device of this experiment, directly determines the accuracy and safety of underwater pressure sensor calibration. However, the high-pressure environmental chambers currently used in calibration processes have many limitations, including low pressure limits, easily cracked light-transmitting windows, seals that are easily squeezed out and fail under high pressure, and the risk of quartz glass windows shattering in high-pressure environments. Furthermore, existing technologies generally lack effective real-time leakage risk detection mechanisms and millisecond-level safety response capabilities, making them difficult to meet the needs of simulation and safety experiments in extreme deep-sea environments. Summary of the Invention

[0004] This invention belongs to the technical field of high-pressure experimental equipment, specifically to a light-transmitting experimental chamber structure suitable for simulating 100MPa ultra-high-pressure environments. This chamber can simulate deep-sea environments up to 10,000 meters deep. The chamber is particularly useful for dynamic calibration systems of underwater pressure sensors based on laser-induced cavitation, but can also be expanded to applications requiring in-situ optical observation, such as high-pressure material performance testing.

[0005] Ultra-high pressure, safe, and light-transmitting environmental chamber for calibrating laser cavitation underwater pressure sensors, including:

[0006] The pressure-bearing box is made of a metal matrix with a cylindrical inner cavity, which is used to contain the liquid medium required for calibration and withstand the ultra-high pressure environment;

[0007] The visual observation channel includes multiple observation ports, each of which adopts a conical transition structure. The inner wall of the box is a large circular hole, which shrinks to a small circular hole toward the outside of the box and is threaded. The end of the large circular hole is processed with threads, and a trapezoidal sealing groove is provided at the root of the thread, with a sealing ring pre-installed in the groove. The transparent compression cover can engage with the threads of the large circular hole to fix and compress the sapphire glass window, forming a visual observation channel with dynamic sealing enhancement capabilities.

[0008] The pressure sensor installation port is arranged on the surface of the pressure box, and a threaded hole is processed on the bottom surface for installing the pressure sensor. During installation, a sealing ring is installed at the bottom, and the combined thread can achieve sealing in an ultra-high pressure environment of 100MPa.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] (1) The pressure box structure is designed with an integrated sapphire light hole and flange pressure-increasing and pressure-relieving channels, which can realize liquid filling, precise pressure control and optical in-situ monitoring simultaneously under an ultra-high pressure environment of 100MPa.

[0011] (2) A visual observation channel with sealing capability is constructed, and a pressure-driven dynamic sealing enhancement mechanism is innovatively introduced to adaptively enhance the interface sealing strength with pressure. Through the conical surface matching and dynamic sealing enhancement design, excellent light transmittance and sealing can be maintained under high-pressure environments, thereby taking into account both optical observation needs and interface sealing enhancement.

[0012] (3) The least squares algorithm is integrated to construct a leakage prediction model, and the sealing failure warning index E(t) is calculated through real-time pressure fluctuation analysis. When E(t) ≥ 0.5, high-speed pressure relief and power interlock protection are triggered, realizing intelligent safety control of the entire process of ultra-high pressure experiments from risk prediction to active protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the ultra-high pressure safety light-transmitting environmental chamber used for calibrating laser cavitation underwater pressure sensors;

[0014] Figure 2 Cross-section of the ultra-high pressure safety light-transmitting environmental chamber used for calibrating laser cavitation underwater pressure sensors;

[0015] Figure 3 It is a cross-sectional view of the assembly of the transparent pressing cover and the observation port;

[0016] Figure 4 Schematic diagram of sapphire glass structure;

[0017] Figure 5 Assemble the schematic diagram for visualizing the observation channel;

[0018] Figure 6 This is a schematic diagram of the connection between the box and the flange;

[0019] Figure 7 It is the top view and cross-sectional view of the pressure sensor installation port;

[0020] Figure 8 This is the workflow diagram of the leakage prediction model. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and examples.

[0022] like Figures 1 to 7 As shown, this embodiment proposes a light-transmitting environmental chamber for optical monitoring and safety control in ultra-high-pressure environments. This embodiment includes a flange 1, a pressure-bearing chamber 2, a visual observation channel 3, a pressure sensor mounting port 4, an observation port 5, a transparent compression cover 6, a sapphire glass window 7, a flange connection component 8, a flange 9, a double-layer sealing structure 10, and threaded holes 11. Its core innovation lies in the coordinated design of a composite pressure-bearing structure, a sealing mechanism, and an intelligent safety system. Through structural innovation and functional integration, it achieves optical monitoring and safety control in ultra-high-pressure environments, resolving the technical challenge of balancing optical visualization and equipment reliability in high-pressure environments.

[0023] The pressure-bearing box is machined from a metal matrix to form a cylindrical inner cavity. Three viewing windows are provided on the box, each with a conical transition structure. Each set of windows consists of a large circular hole on the inner wall of the box, which shrinks toward the outside of the box to become a small circular hole with threads. The large circular hole is threaded, and a trapezoidal sealing groove is provided at the root of the thread, with a sealing ring pre-installed in the groove. A transparent clamping cover engages with the threads of the large circular hole to secure and compress the sapphire glass window. The clamping cover undergoes axial displacement under the action of medium pressure, and dynamic enhancement of the interface sealing performance is achieved through the transmission of conical contact pressure. By combining the optical transmission properties of sapphire material with the high strength properties of metal structures, a visual observation channel with dynamic sealing enhancement capabilities is constructed.

[0024] In one embodiment, the pressure box 2 is made of stainless steel precision casting, and the cross-sectional view of the entire box is as follows: Figure 2 As shown. There are three observation ports 5 on it. Among them, the first and second observation ports are arranged in parallel, and respectively undertake the functions of lighting and high-speed camera shooting; the third observation port adopts a layout perpendicular to the first two, and is dedicated to the laser incident path. All observation ports 5 adopt a conical transition design: the inner wall end of the box is a large end circular hole, which gradually shrinks to a small end circular hole toward the outside of the box. The end of the large end circular hole is processed with a thread, and a trapezoidal sealing groove is provided at the root of the thread, and a fluororubber O-ring is pre-installed in the groove. As shown Figure 3As shown, the transparent pressing cover 6 can be engaged with the thread of the large end circular hole and tightly matched with the metal shell, thereby fixing and pressing the sapphire glass window 7. The overall structure forms a Figure 4 As shown in the visualization observation channel with dynamic sealing capability, the sapphire glass window 7 is precisely processed into a matching truncated cone structure, such as Figure 5 Its surface is frosted to enhance sealing, and its light transmittance at 600nm wavelength exceeds 85%.

[0025] The core sealing mechanism of this design lies in its dynamic reinforcement design: when the pressure of the medium inside the box increases, the pressure acts on the compression cover, causing it to undergo axial displacement toward the outside of the box. This displacement is transmitted through the components, further compressing the O-ring in the trapezoidal sealing groove, thereby achieving adaptive reinforcement sealing under high pressure. This structure effectively suppresses interfacial leakage in high-pressure environments of 100 MPa.

[0026] The box body is welded with a pressure-bearing component, with a central through-hole and a welded flange connection 8. The flange integrates a pressure relief valve, a pressurizing device, and a liquid filling module. A double sealing structure 10 is provided on the flange end face to ensure connection reliability. The pressure-bearing box body has a pressure sensor mounting port on its surface, with threaded holes machined into its bottom surface for mounting the pressure sensor. During installation, a sealing ring is installed at the bottom, which, in conjunction with the threads, ensures a seal even under ultra-high pressures of 100 MPa. The two mounting ports are symmetrically positioned along the axis, ensuring that the centers of the pressure-sensing surfaces of the two sensors are aligned and adjacent to each other after installation.

[0027] In one embodiment, the box body and the flange connection component 8 are rigidly connected by welding to ensure that the overall structure can withstand an ultra-high pressure environment of 100MPa. A through hole is opened in the center and a flange interface is welded. The flange 9 integrates multiple key functional modules, including: a pressure relief valve for safely releasing overpressure; a booster device for establishing and maintaining a high-pressure environment; a liquid filling module for injecting or discharging working medium into the box body. Figure 6 As shown, a double-layer sealing structure 10 is provided on the flange connection end face, the first layer is a thick polytetrafluoroethylene gasket, and the second layer is a copper-nickel alloy metal gasket to ensure connection reliability.

[0028] like Figure 7 As shown, the pressure sensor installation port 4 is arranged on the surface of the pressure box (see Figure 7 a), the bottom surface of the threaded hole 11 (see Figure 7 In b), the pressure sensor can be installed. During installation, a sealing ring is installed at the bottom. The threaded seal ensures sealing even under ultra-high pressures up to 100 MPa. The two mounting ports are symmetrically positioned along the axis, ensuring that the centers of the pressure-sensing surfaces of the two sensors are aligned and adjacent to each other after installation.

[0029] This application further constructs a leakage prediction model based on recursive least squares method. The workflow of the model is as follows: Figure 8 As shown, the model utilizes the output signal data of the standard pressure sensor collected in real time during the calibration process to simultaneously assess the sealing status and predict the risk of seal failure. The model also features abnormality diagnosis and emergency interlock protection, responding to pressure anomalies within milliseconds and triggering a pressure relief action, thereby shutting off the booster pump power. The model calculates the seal failure warning index E(t) in real time and determines whether pressure fluctuations exceed a safety threshold. When E(t) ≥ 0.5, this is considered a safety threshold, triggering an audible and visual alarm, activating the piezoelectric ceramic high-speed pressure relief valve, and achieving a pressure relief rate of 200 L / min, and shutting off the booster pump power.

[0030] The present invention provides an experimental platform with high pressure bearing capacity, optical visualization and active safety protection for dynamic sensor calibration of pressure sensors and verification of precision instruments.

[0031] Furthermore, the principle of the leakage prediction model based on recursive least squares method is as follows:

[0032] Assume that the standard sensor output sequence is P(t), and establish an autoregressive model to predict the current pressure value through historical pressure data:

[0033]

[0034] In the formula is the current pressure prediction value; n is the model order, indicating the length of historical data; θ i (t) is a time-varying weight parameter reflecting the contribution of historical pressure to the current value; ε(t) is the prediction residual, representing the degree of deviation between the actual pressure and the model. Under normal operating conditions, the residual ε(t) is small. However, when a leak occurs, the pressure fluctuates abnormally, and the residual increases significantly.

[0035] Next, the parameters are updated. The parameter update equation is as follows:

[0036]

[0037] where φ(t)=[P(t-1),P(t-2),...,P(tn)] T

[0038] θ(t)=[θ1(t),θ2(t),...,θn(t)] T

[0039] Where φ(t) is the regression vector, composed of historical pressure data, and θ(t) is the weight parameter vector. By updating the weight parameter θ(t) in real time, the sum of squared prediction residuals can be minimized, thereby adaptively tracking pressure changes. λ is the forgetting factor, λ∈(0,1], which is used to reduce the weight of old data. P(t) is the covariance matrix, which is used to dynamically adjust the parameter update amplitude.

[0040] The real-time residual reflects the deviation between the actual pressure and the predicted value. Under normal fluctuations, ε(t) obeys a zero-mean Gaussian distribution and exhibits non-Gaussian characteristics during leakage. Its expression is as follows:

[0041]

[0042] The seal failure warning index E(t) is calculated based on the above formula, and the pressure fluctuation is determined by the seal failure warning index E(t). The expression is as follows.

[0043]

[0044] Where N is the number of sampling points in the time window N = f s T, where T = 500ms, f s is the sampling frequency; σ 2 is the pressure noise variance, obtained through offline calibration; E(t) is the normalized fluctuation index, which is used to quantify the degree of pressure anomaly.

[0045] When E(t)≥0.5, the pressure fluctuation is determined to exceed the safety threshold, the alarm is immediately triggered, the pressure relief valve is opened, and the power supply of the booster pump is cut off.

[0046] In summary, the ultra-high pressure safety light-transmitting environment chamber proposed in this application can realize optical monitoring and safety control in ultra-high pressure environments, and can simulate deep-sea environments up to 10,000 meters deep. The sapphire window achieves high-pressure light transmission and enhanced interface sealing through structural innovation, which can effectively suppress leakage in an ultra-high pressure environment of 100MPa. The intelligent safety control system can be based on a leakage prediction model and, based on the standard pressure sensor data in the water tank collected in real time during the calibration process, dynamically evaluate the sealing status and predict potential sealing failure risks while completing the sensor calibration, providing active protection for system safety. This technology provides an innovative solution for in-situ observation and reliable sealing in extreme high-pressure environments, and promotes the development of high-pressure experimental equipment towards higher parameters and greater intelligence.

[0047] The present invention is not limited to the above-mentioned embodiments, and all equivalent changes and modifications made within the scope of application of the present invention should fall within the scope of the present invention.

Claims

1. Ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration, characterized by: include: The pressure-bearing box (2) is formed by processing a metal base into a cylindrical inner cavity, which is used to contain the liquid medium required for calibration and withstand the ultra-high pressure environment; A visual observation channel (3) includes a plurality of observation ports (5), each of which adopts a conical transition structure, wherein the inner wall of the box body is a large end circular hole, which shrinks toward the outer side of the box body to become a small end circular hole and is provided with a thread; the end of the large end circular hole is processed with a thread, and a trapezoidal sealing groove is provided at the root of the thread, and a sealing ring is pre-installed in the groove; a transparent pressing cover (6) can be engaged with the thread of the large end circular hole, thereby fixing and pressing the sapphire glass window (7), forming a visual observation channel with dynamic sealing enhancement capability; The pressure sensor installation port (4) is arranged on the surface of the pressure-bearing box (2), and a threaded hole (11) is processed on the bottom surface thereof for installing the pressure sensor. During installation, a sealing ring is installed at the bottom thereof, and the combined thread can achieve sealing in an ultra-high pressure environment of 100 MPa.

2. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to claim 1, characterized in that: It also includes a flange connection component (8) welded to the pressure-bearing box (2), with a through hole in the center and a flange interface welded thereto. The flange is integrated with a pressure relief valve, a pressurizing device, and a liquid filling module. A double sealing structure is provided on the flange end face to ensure connection reliability.

3. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to claim 1 or 2, characterized in that: The sapphire glass window (7) is precisely machined into a matching truncated cone structure, the surface is frosted to enhance sealing, and the light transmittance at a wavelength of 600 nm exceeds 85%.

4. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to claim 2, characterized in that: The flange end face of the flange connection component (8) is provided with a double-layer sealing structure (10), the first layer being a thick polytetrafluoroethylene gasket and the second layer being a copper-nickel alloy metal gasket, to ensure connection reliability.

5. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to claim 1, characterized in that: The observation ports (5) include a first observation port and a second observation port arranged in parallel, which respectively undertake the functions of lighting and high-speed camera shooting; and a third observation port is arranged perpendicular to the first two and is dedicated to the laser incident path.

6. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to claim 1 or 5, characterized in that: The pressure sensor mounting openings (4) are symmetrically arranged along the axis, so that after installation, the centers of the pressure-sensing surfaces of the two sensors are located in the same straight line, and the centers of the pressure-sensing surfaces are close to each other.

7. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to claim 1, characterized in that: It also includes an intelligent safety unit, which has a leakage prediction model built based on the recursive least squares method. It uses the output signal data of the standard pressure sensor collected in real time during the calibration process to evaluate the sealing status and predict the risk of sealing failure.

8. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to claim 7, characterized in that: The leakage prediction model is constructed based on the recursive least squares method, and the sum of squares of the prediction residuals is minimized by updating the weight parameters in real time, thereby adaptively tracking the pressure change pattern.

9. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to claim 8, characterized in that: The leakage prediction model calculates the seal failure warning index by real-time pressure fluctuation analysis E (t), when E When (t)≥0.5, high-speed pressure relief and power interlock protection are triggered, realizing intelligent safety control of the entire process of ultra-high voltage experiments from risk prediction to active protection.

10. The ultra-high pressure safety light-transmitting environmental chamber for laser cavitation underwater pressure sensor calibration according to any one of claims 7 to 9, characterized in that: The intelligent safety unit can respond to pressure anomalies and trigger pressure relief within milliseconds, with a pressure relief rate of 200 L / min, and cut off the power supply to the booster pump.

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