Non-contact measuring device for internal pressure of thin-walled cylindrical pressure vessel

Abstract

The utility model relates to pressure measurement technical field especially relates to thin -walled cylinder formula pressure vessel's internal pressure non -contact measuring device, including strain sensing array, by at least three along the pressure vessel outer wall circumferential even distribution's axial strain sensor constitutes, for synchronous measurement each distribution point's axial strain, signal measurement circuit is connected with every strain sensor in strain sensing array, is used for obtaining and outputting each measurement point's real -time axial strain measurement value, processing unit is connected with signal measurement circuit communication, calculates distribution consistent degree index based on at least three real -time axial strain measurement value, according to distribution consistent degree index selection corresponding pressure calculation strategy, is based on real -time axial strain measurement value calculation and is outputted internal pressure estimation of pressure vessel, thereby realizes high -precision, high -reliability non -contact measurement.

Description

Technical Field

[0001] This utility model relates to the field of pressure measurement technology, and in particular to a non-contact measurement device for the internal pressure of a thin-walled cylindrical pressure vessel. Background Technology

[0002] For measuring the internal pressure of pressure vessels, the traditional method is to open a pressure tapping hole in the vessel wall and install a pressure gauge or pressure transmitter through a threaded connection. This method has obvious drawbacks in high-pressure, high-sealing-requirement, or corrosive media: the pressure tapping port itself becomes a potential leak point, and the direct contact of the pressure sensor's sensitive element with the corrosive medium can lead to measurement failure, shortened lifespan, and safety risks.

[0003] Some existing technologies employ non-contact indirect measurement methods based on external wall strain measurement. The basic principle is that under internal pressure, the outer wall of a thin-walled cylinder will generate axial and circumferential elastic strain proportional to the internal pressure. By attaching resistance strain gauges to the outer wall and measuring the strain value, the internal pressure can be calculated using the elasticity formula (i.e., P={4Et / [D(1-2μ)]}*ε_x). To improve reliability, a redundant design with multiple (e.g., four) strain gauges evenly arranged circumferentially is usually adopted.

[0004] However, in practical engineering applications, especially under complex conditions such as long-term service, material micro-inhomogeneity, welding residual stress, non-uniform external constraints, or temperature fields, the aforementioned existing non-contact measurement methods still have the following technical shortcomings: Multiple discrete strain gauges can only sense the strain at a few local "points" on the outer wall of the container. When the overall strain field of the container is not ideally uniform due to manufacturing, installation or use reasons, the simple average value of the measurements at these discrete points may not accurately represent the overall average axial strain used for theoretical calculations, resulting in systematic pressure calculation errors. The output signal of a strain gauge is the result of the combined effects of multiple factors such as internal pressure, ambient temperature changes, and material creep / relaxation. Existing methods rely on fixed material parameters (elastic modulus E, Poisson's ratio μ), which cannot dynamically distinguish and compensate for the coupling interference caused by temperature changes and time-varying material properties in long-term monitoring, resulting in difficult-to-correct drift in readings under static or slowly varying pressure. Existing multi-gauge redundancy designs utilize data in a rudimentary manner, typically limited to simple fault alarms (such as a circuit failure) or calculating the arithmetic mean. They fail to fully exploit the overall deformation state information of the container contained in the spatial distribution information of multiple strain gauges, thus failing to identify and correct errors caused by the non-uniformity of the strain field, and also failing to achieve higher-level system self-diagnosis and self-adaptation.

[0005] Therefore, to address the aforementioned issues, a non-contact measurement method and device for the internal pressure of a thin-walled cylindrical pressure vessel is proposed. The discrete strain gauge measurement points are considered as sparse sampling of a continuous strain field. The uniformity of the strain field is evaluated by analyzing the data consistency of these sampling points, and the optimal pressure calculation strategy is intelligently selected accordingly. At the same time, an environmental parameter monitoring and model self-learning mechanism are introduced to dynamically compensate for interference, thereby achieving high-precision and high-reliability non-contact measurement. Utility Model Content

[0006] In order to overcome the problems of pressure calculation errors affecting measurement accuracy and insufficient stability caused by environmental interference and long-term drift in the existing methods for measuring the internal pressure of pressure vessels.

[0007] The technical solution of this utility model is as follows: A non-contact internal pressure measuring device for a thin-walled cylindrical pressure vessel, comprising: The strain sensing array consists of at least three axial strain sensors uniformly arranged circumferentially along the outer wall of the pressure vessel, used to synchronously measure the axial strain at each arrangement point. The signal measurement circuit is connected to each strain sensor in the strain sensing array and is used to acquire and output the real-time axial strain measurement value of each measurement point. The processing unit, which is communicatively connected to the signal measurement circuit, is configured as follows: Receive the real-time axial strain measurement value; Calculate the distribution consistency index based on the at least three real-time axial strain measurements; Select the corresponding pressure calculation strategy based on the distribution consistency index, and calculate and output the estimated internal pressure of the pressure vessel based on the real-time axial strain measurement value.

[0008] Preferably, the strain sensing array includes four axial strain sensors, which are evenly spaced at 90-degree intervals along the circumferential direction of the outer wall of the pressure vessel.

[0009] Preferably, the axial strain sensor is a metal strain gauge, and the axis of its sensing grid is parallel to the axis of the pressure vessel.

[0010] Preferably, the device further includes a temperature sensor configured to measure the temperature of the outer wall of the container in the strain sensing array region and to communicate with the processing unit; the processing unit is further configured to receive the temperature of the outer wall of the container and, based on historical data of the temperature value and / or estimated internal pressure, dynamically correct the material parameters used for pressure calculation.

[0011] Preferably, the processing unit is configured to: select a pressure calculation strategy as follows: When the distribution consistency index is higher than the first preset threshold, the first calculation module is used, which calculates based on the statistics of the at least three real-time axial strain measurements. When the distribution consistency index is lower than the second preset threshold, the second calculation module is used. This module performs the following operations: identifying and eliminating outliers in the measured values, constructing an axial strain distribution model based on the remaining valid measured values ​​and their spatial locations, calculating the equivalent axial strain through the model, and calculating the estimated internal pressure based on this model. Wherein, the second preset threshold is less than or equal to the first preset threshold.

[0012] The beneficial effects of this utility model are: The change in the distribution consistency index output by this invention can indirectly reflect the structural health status of the pressure vessel. For example, when the vessel becomes out of round, bulges locally, or is subjected to abnormal external constraints, this index will drop significantly. Therefore, while performing pressure measurement, this device can also provide early warning signals for the safety status assessment of the vessel, thus expanding its functionality. Attached Figure Description

[0013] Figure 1 The diagram shows the internal pressure non-contact measuring device and the three-dimensional assembly structure of the thin-walled cylindrical pressure vessel of this utility model. Figure 2 The diagram shown is a cross-sectional view of the internal pressure non-contact measuring device and the container assembly of the thin-walled cylindrical pressure vessel of this utility model. Figure 3 The diagram shown is a partial structural schematic of the non-contact internal pressure measuring device of the thin-walled cylindrical pressure vessel of this utility model. Explanation of reference numerals in the attached figures: 1. Strain sensor array; 2. Temperature sensor. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] Example 1 Please see Figure 1 , Figure 2 , Figure 3 .

[0016] A non-contact internal pressure measuring device for a thin-walled cylindrical pressure vessel, used to implement the above method, includes: The strain sensing array 1 consists of at least three axial strain sensors uniformly arranged along the circumference of the outer wall of the pressure vessel, used to synchronously measure the axial strain at each arrangement point. The signal measurement circuit is connected to each strain sensor in the strain sensing array 1 and is used to acquire and output the real-time axial strain measurement value of each measurement point. The processing unit, which is communicatively connected to the signal measurement circuit, is configured as follows: Receives real-time axial strain measurements; Calculate the distribution consistency index based on at least three real-time axial strain measurements; Select the corresponding pressure calculation strategy based on the distribution consistency index, and calculate and output the estimated internal pressure of the pressure vessel based on the real-time axial strain measurement value.

[0017] Furthermore, the strain sensing array 1 includes four axial strain sensors, which are evenly spaced at 90-degree intervals along the circumference of the outer wall of the pressure vessel. The four-point arrangement is the best balance between cost and the ability to acquire circumferential distribution information, and can effectively capture low-order non-uniform modes such as possible elliptic deformation.

[0018] Furthermore, the axial strain sensor is a metal strain gauge, with the axis of its sensitive grid parallel to the axis of the pressure vessel to ensure accurate measurement of axial strain.

[0019] Furthermore, the device also includes a temperature sensor 2, which is configured to measure the temperature of the outer wall of the container in the region of the strain sensor array 1 and is communicatively connected to the processing unit; the processing unit is further configured to receive the temperature of the outer wall of the container and dynamically correct the material parameters used for pressure calculation based on historical data of the temperature value and / or the internal pressure estimate; thereby realizing temperature compensation and model self-calibration.

[0020] Furthermore, when selecting a stress calculation strategy, the processing unit is specifically configured to execute a judgment logic: When the distribution consistency index is higher than the first preset threshold, the strain field is determined to be highly uniform, and the first calculation module is called to execute the first strategy for calculation.

[0021] When the distribution uniformity index is lower than the second preset threshold (the second preset threshold ≤ the first preset threshold), it is determined that there is obvious non-uniformity in the strain field, and the second calculation module is called to execute the second strategy for calculation.

[0022] If the metric falls between the two, a weighted fusion or a default strategy can be used for processing.

[0023] Through the above steps, this invention treats discrete strain gauge measurement points as sparse sampling of a continuous strain field, evaluates the uniformity of the strain field by analyzing the data consistency of these sampling points, and intelligently selects the optimal pressure calculation strategy accordingly. At the same time, it introduces environmental parameter monitoring and model self-learning mechanisms to dynamically compensate for interference, thereby achieving high-precision and high-reliability non-contact measurement.

[0024] Example 2 Optionally, this utility model also provides an embodiment.

[0025] In this embodiment, the measuring device mainly consists of the following parts: Strain sensing array 1: Four identical metal resistance strain gauges (e.g., nominal resistance 350Ω, sensitivity coefficient K=2.0) are used. These four strain gauges (marked as R1, R2, R3, R4) are uniformly pasted circumferentially along the same circumferential cross-section of the outer wall of the thin-walled cylindrical pressure vessel being measured. During pasting, it is ensured that the sensitive grid axis of each strain gauge is strictly parallel to the axial direction of the vessel to sense axial strain. The circumferential angle between the four strain gauges is 90 degrees.

[0026] Signal measurement circuit: A full-bridge or half-bridge measurement circuit is used; four strain gauges (R1-R4) serve as the four arms of the bridge (or two of them are measurement arms and the other two are temperature-compensated fixed resistors), connected to the signal conditioning module; this module includes an excitation power supply, an amplifier, a filter, and an analog-to-digital converter (ADC) to convert the strain gauge resistance change into a digital voltage signal, and finally calculate four independent real-time axial strain measurements (ε1, ε2, ε3, ε4); the signal conditioning module acquires data from the four channels in a synchronous sampling manner to ensure the time consistency of the data.

[0027] Processing unit: can be a microcontroller (MCU), digital signal processor (DSP) or industrial computer; it is connected to the ADC output of the signal measurement circuit to receive and process strain digital signals from four channels.

[0028] During service, changes in internal pressure cause deformation of the outer wall of the container. Four attached strain gauges synchronously sense the axial strain at their locations and convert it into electrical signals through a measurement circuit. The processing unit executes steps S2-S4 in a loop and outputs the estimated internal pressure P_est calculated based on the current strain field state using an intelligent selection strategy in real time. This scheme uses a high-precision average value when the strain field is uniform and automatically switches to the median method, which has stronger anti-interference capabilities, when non-uniformity occurs. Compared with the traditional method that uses the average value, the overall measurement accuracy and robustness are improved.

[0029] Example 3 Optionally, this utility model also provides an embodiment.

[0030] This embodiment adds the following components to the device of embodiment 2: Temperature sensor 2: A non-contact infrared temperature sensor 2 or a contact patch temperature sensor 2, installed on the outer wall of the container, for real-time measurement of the wall temperature T in the area where the strain gauge array is located.

[0031] Enhanced processing unit: It has computing power and storage space to run more complex algorithms.

[0032] In routine measurements, the processing unit uses the current temperature T and the latest estimated pressure P_est to calculate E_corrected and μ_corrected in real time based on the updated dynamic model. It then replaces the fixed parameters E and μ with these values ​​and substitutes them into the pressure calculation formula. Finally, it outputs the internal pressure value P_final, which has been compensated for by temperature and time-varying effects.

[0033] During operation, the device in this embodiment not only performs strain measurement and consistency judgment, but also monitors temperature and runs a background self-calibration algorithm. When the strain field is severely non-uniform, it can reconstruct the strain distribution of the entire circumference by modeling, calculate the equivalent average strain that is more in line with mechanical meaning, and reduce the error caused by non-uniform deformation. At the same time, the temperature compensation and parameter self-learning mechanism work continuously to dynamically counteract temperature drift and slow changes in material properties, ensuring the stability and accuracy of long-term measurements. In addition, the output distribution consistency index η itself can serve as an auxiliary monitoring parameter for the health status of the container structure.

[0034] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A non-contact measuring device for the internal pressure of a thin-walled cylindrical pressure vessel, characterized in that, include: The strain sensing array (1) consists of at least three axial strain sensors uniformly arranged along the circumference of the outer wall of the pressure vessel, used to synchronously measure the axial strain at each arrangement point. The signal measurement circuit is connected to each strain sensor in the strain sensing array (1) to acquire and output the real-time axial strain measurement value of each measurement point; The processing unit, which is communicatively connected to the signal measurement circuit, is configured as follows: Receive the real-time axial strain measurement value; Calculate the distribution consistency index based on the at least three real-time axial strain measurements; Select the corresponding pressure calculation strategy based on the distribution consistency index, and calculate and output the estimated internal pressure of the pressure vessel based on the real-time axial strain measurement value.

2. The non-contact internal pressure measuring device for a thin-walled cylindrical pressure vessel according to claim 1, characterized in that: The strain sensing array (1) includes four axial strain sensors, which are evenly spaced at 90-degree intervals along the circumferential direction of the outer wall of the pressure vessel.

3. The non-contact internal pressure measuring device for a thin-walled cylindrical pressure vessel according to claim 1, characterized in that: The axial strain sensor is a metal strain gauge, and the axial direction of its sensing grid is parallel to the axial direction of the pressure vessel.

4. The non-contact internal pressure measuring device for a thin-walled cylindrical pressure vessel according to claim 1, characterized in that: The device also includes a temperature sensor (2), which is configured to measure the temperature of the outer wall of the container in the region of the strain sensing array (1) and is communicatively connected to the processing unit; the processing unit is further configured to receive the temperature of the outer wall of the container and dynamically correct the material parameters used for pressure calculation based on historical data of the temperature value and / or the internal pressure estimate.

5. The non-contact internal pressure measuring device for a thin-walled cylindrical pressure vessel according to claim 1, characterized in that: When selecting a pressure calculation strategy, the processing unit is configured as follows: When the distribution consistency index is higher than the first preset threshold, the first calculation module is used, which calculates based on the statistics of the at least three real-time axial strain measurements. When the distribution consistency index is lower than the second preset threshold, the second calculation module is used. This module performs the following operations: identifying and eliminating outliers in the measured values, constructing an axial strain distribution model based on the remaining valid measured values ​​and their spatial locations, calculating the equivalent axial strain through the model, and calculating the estimated internal pressure based on this model. Wherein, the second preset threshold is less than or equal to the first preset threshold.

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