CN114486057A

CN114486057A - Non-contact pressure measuring method and system based on strain and temperature sensors

Info

Publication number: CN114486057A
Application number: CN202111682834.1A
Authority: CN
Inventors: 郑显锋; 白伟; 何卫东
Original assignee: Measuring And Testing Institute Under Xi'an Aerospace Corp
Current assignee: Measuring And Testing Institute Under Xi'an Aerospace Corp
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2022-05-13

Abstract

The invention relates to a non-contact pressure measuring method, especially a non-contact dynamic pressure measuring method and system based on strain and temperature sensor, the measuring method and system adopts non-contact measuring mode isolated from pressure sensing medium to reduce pressure leakage risk point of whole pressure loop, non-contact measuring mode is adopted to measure strain change caused by pressure by non-contact with pressure transmitting medium, then temperature correction is carried out to obtain pressure data indirectly, on the basis of uniform material and performance of pipeline or container (generally, curved surface), the internal pressure change and strain and temperature of pressure sensing wall are in corresponding proportion (relevant verification test is carried out), dynamic pressure correction is added at the same time, real-time measurement of dynamic change of pressure in pipeline or container is realized by measuring strain and temperature of pressure sensing wall, the purpose of non-contact dynamic pressure measurement is achieved. The method can reduce the risk points of the pressure loop, improve the reliability of the high-pressure pipeline equipment, and has high universality and popularization.

Description

Non-contact pressure measuring method and system based on strain and temperature sensors

Technical Field

The present invention relates to a non-contact pressure measurement method, and more particularly, to a non-contact pressure measurement method and system based on strain and temperature sensors.

Background

With the rapid development of high-precision machining and high-precision measurement technologies, the requirements for pressure measurement in scientific research and production are higher and higher.

The traditional pressure measurement is generally realized by connecting a pressure measurement instrument to a part to be measured, but aiming at some fields, particularly the field of high-pressure measurement, a contact pressure measurement point is added in the whole pressure loop, and a leakage risk point is introduced into the whole pressure loop. The problems in the high-risk fields of aerospace, precision measurement/monitoring and the like are particularly obvious; in such fields, the demand for miniaturization and miniaturization of measuring equipment is increasing day by day, but the traditional method is difficult to meet the demand because of the additional leakage risk due to the introduction of a pressure meter in contact with the pressure transmission medium.

Chinese patent 2020105845917 discloses a non-contact pressure measurement method based on strain and temperature sensor measurement, which uses non-contact measurement, i.e. measures the strain variation caused by pressure by non-contact with pressure transmission medium, then makes temperature correction to obtain pressure data indirectly, on the basis of uniform material and performance of pipeline or container (generally, curved surface), the internal pressure variation is in corresponding proportion to the strain and temperature of pressure sensing wall (relevant verification test is already made), and realizes the measurement of the internal pressure of pipeline or container by measuring the strain and temperature of pressure sensing wall, thus realizing the purpose of non-contact pressure measurement.

However, the measurement system based on the method can only realize static pressure measurement, and the measurement system has a large volume and is inconvenient to carry.

Disclosure of Invention

The invention aims to provide a pipeline pressure measuring method and system based on a strain sensor, and aims to solve the problems that the conventional detection system cannot realize dynamic pressure and is large in size.

In the pressure relief process, the temperature in the pressure relief pressure loop can be rapidly reduced, and when the temperature of the pressure loop is measured by using the temperature sensor on the pipe wall, the temperature difference (temperature gradient) between the inner wall surface and the outer wall surface is large due to the measurement of the surface temperature, so that the error exists in the process of taking and correcting the pressure data by using the directly measured temperature data. According to the invention, through a large number of tests, the temperature correction introduced by the temperature parameter in the pressure relief process is found out to reduce the error introduced by the factor.

The technical scheme of the invention is to provide a non-contact pressure measurement method based on strain and temperature sensors, which is characterized by comprising a verification test process, a pressure calibration process and a pressure measurement process:

the verification test process comprises the following steps:

static verification test for obtaining strain and measured temperature T_MeasuringPressure corresponding fitting equation:

P＝f₁(ε)+f₂(T_measuring)；

Where P is pressure, ε is strain, T_MeasuringFor actually measuring the temperature, f₁(epsilon) is a pressure versus stress functional relationship; f. of₂(T_Measuring) As a function of pressure and temperature; determining the positions of the final measuring points of the pipeline and corresponding pressure and/or temperature sensors bonded at the positions of the measuring points;

the pressure calibration process comprises the following steps:

1) static pressure calibration:

obtaining a specific static pressure calibration equation of each measuring point position of the calibration pipeline through a static pressure calibration process:

P_n＝f_1n(ε)+f_2n(T_measuring)

Wherein f is_1n(epsilon) is a specific functional relation between pressure and stress at the nth measuring point; f. of_2n(T_Measuring) The specific function relation of pressure and temperature at the nth measuring point position is shown; the calibration pipeline is a pipeline which is obtained in a verification test and is provided with pressure and/or temperature sensors for determining the positions of measuring points and bonding and determining the positions of the measuring points;

2) dynamic pressure calibration:

the following two analytical data were obtained by dynamic pressure calibration test:

a. obtaining the relation between the strain value and the temperature value variation and the corresponding pressure relief rate in the pressure dynamic change process;

b. obtaining the pressure value and the actual dynamic standard pressure which are directly called and calculated by the static pressure calibration equationForce P_{Sign board}Deviation curve in time domain, wherein actual dynamic standard pressure P_{Sign board}Measuring by a dynamic pressure sensor at the position of a measuring point; the deviation of the two is used as the influence of the temperature measurement deviation on the pressure at the current pressure relief rate, and the actual temperature T at the pressure relief rate within a certain range is deduced according to the deviation curve_{Practice of}For measured temperature T in the interval_MeasuringCorrection formula f₃(T_Measuring)；

3) Storing analytical data obtained in the static pressure calibration equation and the dynamic pressure calibration process:

storing specific static pressure calibration equation P of each measuring point position in an acquisition processing memory module of the measuring system_n＝f_1n(ε)+f_2n(T_Measuring) And storing analytical data obtained in the dynamic pressure calibration process;

the acquisition processing memory module comprises a shell, and a signal acquisition unit, a power supply conversion unit, a battery system and an analysis and storage unit which are arranged in the shell;

a sensor interface is arranged on the shell;

the sensor interface is electrically connected with the analysis and storage unit through the signal acquisition unit;

the battery system supplies power to the signal acquisition unit and the analysis and storage unit through the power supply conversion unit;

the signal acquisition unit comprises a plurality of acquisition channels, each acquisition channel comprises an acquisition module, and each acquisition channel corresponds to each sensor in each sensor module one by one;

the pressure measurement process comprises the following steps:

1) connecting a calibration pipeline in the static pressure calibration process with a high-pressure container, acquiring current strain values and temperature values of each measuring point position in a measuring area through a strain sensor and a temperature sensor, and storing the current strain values and the temperature values in an analysis and storage unit of a measuring system acquisition and processing memory module;

2) the analysis and storage unit is used for analyzing and storing a fitting formula P according to the positions of the corresponding measuring points_n＝f_1n(ε)+f_2n(T_Measuring) Calculate the measuring pointA static pressure value in the pipeline at the position before the dynamic change of the pressure begins;

3) taking the static pressure value as a baseline pressure, setting the change conditions of the strain value and the temperature value in a time domain by analyzing the dynamic change process of the pressure, and calculating the pressure relief rate in the time domain based on the analytic data a of the dynamic pressure calibration test;

4) according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{In fact}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝f_1n(ε)+f_2n(T_{Practice of}) Solving the pressure value of the current time domain;

5) and (5) repeating the operations of the step (2) and the step (4) to obtain pressure values in all time domains of the whole dynamic change process, so as to obtain a dynamic pressure measurement curve of the whole dynamic change process.

Further, the static pressure calibration process specifically includes:

measuring multiple groups of temperature, pressure and strain values at different measuring point positions on the calibration pipeline, and substituting the measured values into a fitting formula P ═ f₁(ε)+f₂(T_Measuring) And respectively obtaining a specific static pressure calibration equation at each measuring point position: p_n＝f_1n(ε)+f_2n(T_Measuring)；

Where P is pressure, ε is strain, T_MeasuringFor actually measuring the temperature, f₁(epsilon) is a pressure versus stress functional relationship; f. of₂(T_Measuring) As a function of pressure and temperature.

Further, the dynamic pressure calibration test specifically comprises the following steps:

firstly, a dynamic pressure measuring sensor is uniformly arranged at each measuring point position of a pipeline used for a static verification test, a simulated pressure relief test is carried out at set time intervals, the dynamic pressure measuring sensor is used for measuring the pressure value of the pipeline at the corresponding measuring point position, and the pressure value is the actual dynamic standard pressure P_{Sign board}；

Collecting the variation of the strain value and the temperature value measured by the strain sensor and the temperature sensor at each measuring point position in the process of simulating the pressure release test on the basis of the strain value and the temperature value before the pressure dynamic change begins; establishing a relation between a strain value and a temperature value variation and a corresponding pressure relief rate in the pressure dynamic variation process;

(f) based on P ═ f₁(ε)+f₂(T_Measuring) Acquiring a pressure value calculated under multiple simulated pressure relief tests;

drawing the pressure value in the step (c) and the actual dynamic standard pressure P measured by the dynamic pressure measuring sensor under the test of simulating pressure release for many times_{Sign board}Obtaining a deviation curve of the pressure value calculated by directly calling the static pressure calibration equation and the actual dynamic standard pressure in a time domain, taking the deviation of the pressure value and the actual dynamic standard pressure as the influence of the temperature measurement deviation on the pressure at the current pressure relief rate, and deducing the actual temperature T at the pressure relief rate in a certain range according to the deviation curve_{Practice of}For measured temperature T in the interval_MeasuringCorrection formula f₃(T_Measuring)。

Further, aiming at pipelines made of stainless steel and titanium alloy, the strain and the measured temperature T are measured_MeasuringThe corresponding fitting formula of the pressure is as follows:

P＝aε+bT_measuring ³+cT_Measuring ²+dT_Measuring+e₁+e₂

Wherein a and e₁Is and K₁Related constants, b, c, d, e₂Is and K₂A related constant; k₁Is a coefficient of a strain-pressure related function, K₂Is the temperature and pressure related function coefficient;

the specific static pressure calibration equation of each measuring point position is as follows:

P_n＝a_nε+b_nT_measuring ³+c_nT_Measuring ²+d_nT_Measuring+e_1n+e_2n

Wherein a is_nAnd e_1nIs and K_1nConstant of correlation, b_n、c_n、d_n、e₂Is and K_2nConstant of correlationN is the serial number of the measuring point position;

the pressure measurement process, step 5) is specifically:

according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{Practice of}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝a_nε+b_n T_{Practice of} ³+c_n T_{Practice of} ²+d_n T_{Practice of}+e_1n+e_2nAnd solving the pressure value of the current time domain.

Further, the static verification test process is as follows:

selecting a pipeline connected with a high-pressure container, pasting temperature and strain sensors at different measuring point positions, and obtaining a fitting formula by using a plurality of groups of measurement data of temperature, pressure and strain values:

P＝f₁(ε)+f₂(T_measuring)；

Where P is pressure, ε is strain, T_MeasuringFor actually measuring the temperature, f₁(epsilon) is a pressure versus stress functional relationship; f. of₂(T_Measuring) As a function of pressure and temperature; and determining the positions of the final measuring points of the pipeline and corresponding pressure and/or temperature sensors bonded at the positions of the measuring points.

Further, the static verification test process specifically comprises:

step 1a, selecting a pipeline to be tested connected with a high-pressure container as a verification test pipeline;

step 1b, determining the positions and the number of the measuring points on the verification test pipeline and verification conditions, wherein the verification conditions comprise temperature measuring points and pressure measuring points;

step 1c, pasting corresponding strain sensors and temperature sensors at corresponding measuring point positions of the verification test pipeline;

step 1d, placing the verification test pipeline into an environment temperature test box, sealing one end of the verification test pipeline by using a plug, connecting the other end of the verification test pipeline with a standard pressure source, and simulating working states of different temperatures and different pressures;

step 1e, according to the temperature measurement points and the strain measurement points determined in the step 1b, for each measurement point position, pressurizing the verification test pipeline to a pressure measurement point under each temperature measurement point, controlling the temperature to the corresponding temperature measurement point, and recording a strain output value at each measurement point position after the pipeline temperature is stable to obtain a corresponding fitting formula of strain, temperature and pressure;

and step 1f, determining the positions of the final measuring points of the pipeline and corresponding pressure sensors and/or temperature sensors bonded at the positions of the measuring points according to the test data.

Further, the static pressure calibration process specifically includes the following steps:

step 1a, selecting a connecting pipeline determined in a verification test as a calibration pipeline;

step 1b, determining calibration conditions on a calibration pipeline, wherein the calibration conditions comprise a temperature measurement point and a pressure measurement point;

step 1c, placing the calibration pipeline into an environment temperature test box, sealing one end of the calibration pipeline by using a plug, and connecting the other end of the calibration pipeline with a standard pressure source to simulate working states at different temperatures and different pressures;

step 1d, according to the temperature measurement points and the strain measurement points determined in the step 1b, aiming at the positions of each measurement point, pressurizing the calibration pipeline to a pressure measurement point under each temperature measurement point, controlling the temperature to the corresponding temperature measurement point, recording the strain output value at the position of each measurement point after the pipeline temperature is stable, and according to the corresponding relation P (f) of the strain, the temperature and the pressure₁(ε)+f₂(T_Measuring) Obtaining a concrete fitting formula P of the pressure at the position of each measuring point with respect to the temperature and the strain_n＝f_1n(ε)+f_2n(T_Measuring)。

Furthermore, at least one measuring point position is determined through a verification test, and a strain sensor and a temperature sensor are pasted at the measuring point position; the strain sensor is used for testing the radial strain quantity of the pipeline.

Furthermore, the verification test determines 6N measuring point positions, and the measuring point positions are divided into N areas; in each area, strain sensors are pasted at four measuring point positions, and temperature sensors are pasted at the other two measuring point positions; and two strain sensors are in a group, two strain sensors in each group are arranged along the radial top of the pipeline, and two groups of strain sensors are arranged along the axial direction of the pipeline to test the radial strain of the pipeline.

The invention also provides a non-contact pressure measuring system based on the strain and temperature sensors, which is characterized in that: comprises a sensor module and an acquisition processing memory module;

the sensor module comprises at least one strain sensor and a temperature sensor, wherein the strain sensor is attached to the outer side surface of the pipeline and used for sensing pipeline strain change caused by pipeline pressure change, and the temperature sensor is used for measuring the temperature value of the pipeline and correcting the offset of the strain sensor, which is introduced by the influence of temperature, before the dynamic pressure change begins;

the acquisition processing memory module is used for acquiring and storing the measurement data of the sensor module and simultaneously storing a specific static pressure calibration equation P of each measuring point position_n＝f_1n(ε)+f_2n(T_Measuring) And storing analytical data a and b obtained in the dynamic pressure calibration process; and based on the collected sensor module measurement data, according to a fitting formula P at the position of the corresponding measuring point_n＝f_1n(ε)+f_2n(T_Measuring) Calculating a static pressure value before the dynamic change of the pressure in the pipeline at the position of the measuring point begins; taking the static pressure value as a baseline pressure, setting the change conditions of the strain value and the temperature value in a time domain by analyzing the dynamic change process of the pressure, and calculating the pressure relief rate in the time domain based on the analytic data a of the dynamic pressure calibration test; according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{Practice of}Will the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝f_1n(ε)+f_2n(T_{Practice of}) Solving the pressure value of the current time domain; and obtaining the pressure values in all time domains, further obtaining the pressure values in all time domains in the whole dynamic change process, and obtaining the dynamic pressure measurement curve in the whole dynamic change process.

Furthermore, the acquisition processing memory module comprises a shell, and a signal acquisition unit, a power supply conversion unit, a battery system and an analysis and storage unit which are arranged in the shell;

the shell is provided with a sensor interface;

the sensor interface is inserted with a sensor module at the position of a pressure measurement point to be measured, and an acquisition module in a corresponding acquisition channel in the signal acquisition unit converts an acquired signal into a digital signal and sends the digital signal to the analysis and storage unit; the analysis and storage unit is used for analyzing and storing a fitting formula P according to the positions of the corresponding measuring points_n＝f_1n(ε)+f_2n(T_{Side survey}) Calculating a static pressure value before the dynamic change of the pressure in the pipeline at the position of the measuring point begins; taking the static pressure value as a baseline pressure, setting the change conditions of the strain value and the temperature value in a time domain by analyzing the dynamic change process of the pressure, and calculating the pressure relief rate in the time domain based on the analytic data a of the dynamic pressure calibration test; according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{Practice of}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝f_1n(ε)+f_2n(T_{Practice of}) Solving the pressure value of the current time domain; and obtaining the pressure values in all time domains, further obtaining the pressure values in all time domains in the whole dynamic change process, and obtaining the dynamic pressure measurement curve in the whole dynamic change process.

Furthermore, each group of acquisition modules comprises an 1/4 bridge circuit, an amplifying circuit, a following circuit and an AD converter; the analog signal of the sensor passes through an 1/4 bridge circuit, an amplifying circuit and an AD converter, and finally the analog signal is converted into a voltage digital quantity to be output to a system control unit for processing; the 2.5V reference voltage output by the AD converter is used as a voltage reference source of an 1/4 bridge circuit after effective isolation and front-end noise reduction of the follower circuit.

The invention has the beneficial effects that:

1. the invention obtains a concrete static pressure calibration equation static calibration formula for calibrating each measuring point position of the pipeline through a static pressure calibration test, obtains two types of analytical data based on the dynamic pressure calibration test, and stores the static calibration formula and the two types of analytical data in an acquisition processing memory module of a measuring system. The measured data is stored in a memory card in the actual measurement process, the first baseline pressure analysis before dynamic change is carried out by a static pressure measurement method before analysis, and on the basis of the baseline pressure, the real-time pressure relief rate can be obtained through strain and temperature acquisition values based on the analysis data, so that the actual temperature T is obtained_{In fact}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝f_1n(ε)+f_2n(T_{Practice of}) Solving the pressure value of the current time domain; and the measured values are continuously analyzed according to the method in sequence to obtain an accurate dynamic pressure measurement result. The pressure dynamic measurement device is mainly used for pressure dynamic measurement in the flight test process of products in the aerospace field, solves the problem of dynamic measurement of the pressure of a driving gas cylinder in the dynamic process of the products, and provides data support for product optimization. The invention can realize the dynamic pressure non-contact measurement of a pressure container or a pipeline on the spot based on the acquisition processing memory module, during the measurement process, the acquisition processing memory module is only required to be inserted with a pressure and/or temperature sensor on a calibration pipeline connected with a high-pressure container through a sensor interface, and the acquisition module of a corresponding acquisition channel in the signal acquisition unit converts an acquired signal into a digital signal and sends the digital signal to the analysis and storage unit; the analysis and storage unit automatically matches the parameter information of the sensor module, and converts the acquired strain and temperature information of the sensor module into pressure parameter information for outputting and storing by using the specific calibration of the corresponding measuring point position. Simple measurement process and measurement systemThe system is small in size and convenient to carry.

2. According to the invention, a large number of verification tests are carried out at the early stage, and a pipeline characteristic fitting formula P ═ f is obtained according to the test conclusion₁(ε)+f₂(T_Measuring) Obtaining a concrete fitting formula of the temperature, the pressure and the strain value at the position of each measuring point through a calibration test, and substituting the current strain value and the temperature value into a corresponding fitting formula P in the measuring process_n＝f_1n(ε)+f_2n(T_Measuring) The pressure in the current pipeline can be calculated; the pressure data can be obtained by adopting non-contact measurement, risk points of a pressure loop (pressure leakage increased by adding a traditional contact pressure measurement point) are reduced, and the reliability of high-pressure pipeline equipment is improved.

3. The invention adopts the surface mount type sensor, and only needs to paste the sensor on the outer wall of the pipeline to be measured, thereby meeting the requirements of miniaturization and microminiaturization of measuring equipment.

4. The pressure strain test, the temperature strain test, the constant temperature pressure strain test, the repeated constant temperature pressure strain test (oil medium) and the repeated constant pressure strain temperature test prove that the pressure measurement method for measuring the pressure has obvious application effect in the pipeline and controllable measurement precision, can better solve the aim of carrying out non-contact pressure measurement or continuous pressure monitoring at any time in the pipeline, and has bright application prospect.

Drawings

FIG. 1 is a schematic view of a measurement system according to an embodiment of the present invention;

FIG. 2 is a block diagram of an acquisition processing memory module according to an embodiment of the present invention;

FIG. 3 is a functional block diagram of an acquisition processing memory module according to an embodiment of the present invention;

FIG. 4 is a schematic block diagram of an acquisition module of a signal acquisition unit according to an embodiment of the present invention;

FIG. 5 is a circuit diagram of a quarter-bridge circuit according to an embodiment of the present invention;

FIG. 6 is a connection diagram of a validation test according to an embodiment of the present invention;

FIG. 7 illustrates a sensor attachment method during a verification test according to an embodiment of the present invention;

FIG. 8 is a first test data curve of a verification test according to an embodiment of the present invention, which is data of the 3 rd channel of the strain gauge;

FIG. 9 is a second test data curve of a verification test according to the first embodiment of the present invention, which is data of the 4 th channel of the strain gauge;

FIG. 10 is a first strain versus temperature curve for a strain sensor at a fixed pressure;

FIG. 11 is a second curve of strain versus temperature for the strain gauge under constant pressure;

FIG. 12 is a schematic diagram of a determined measurement protocol sensor attachment location in accordance with one embodiment of the present invention;

FIG. 13 is a graph illustrating the deviation between the non-contact sensor measurement and the contact sensor measurement according to an embodiment of the present invention;

FIG. 14 is a graph showing the deviation between the measured value of the non-contact sensor and the measured value of the contact sensor at a specific pressure relief rate, and a pressure relief process curve according to a first embodiment of the present invention; a is a deviation curve of a value measured by a non-contact sensor and a value measured by a contact sensor under a specific pressure relief rate; b is a pressure relief process curve;

FIG. 15 is a graph showing the deviation between the non-contact sensor measurement and the contact sensor measurement at another pressure relief rate, and a pressure relief process curve according to another embodiment of the present invention; a is a deviation curve of a value measured by a non-contact sensor and a value measured by a contact sensor under a specific pressure relief rate; b is a pressure relief process curve;

FIG. 16 shows a strain sensor attachment method for a second verification test according to an embodiment of the present invention;

FIG. 17 shows the strain variation of the measuring point position 8 under pressure variation at different temperatures in the second verification test according to the embodiment of the present invention;

FIGS. 18 to 27 are graphs showing the changes of strain with pressure at the measuring point positions 8 at-10 deg.C, -5 deg.C, 0 deg.C, 10 deg.C, 20 deg.C-1, 20 deg.C-2, 20 deg.C-3, 25 deg.C, 30 deg.C and 40 deg.C, respectively, in the second verification test of the example of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, and it is apparent that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention, shall fall within the protection scope of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Example one

The measurement system of the present embodiment is shown in fig. 1, and mainly includes a sensor module and an acquisition processing memory module. The pressure monitoring device is suitable for dynamic monitoring of the pressure in the pressure gas cylinder and the pressure in the pipeline, and provides data support for dynamic change data analysis of the pressure in dynamic equipment facilities. The design is carried out according to the mode of the sensor module and the acquisition processing memory module in the implementation of the equipment, so that the configuration modes of a plurality of sensor modules and acquisition processing memory modules can be realized.

The sensor module is arranged on the outer wall surface of the pipeline (can be positioned in the middle), and comprises at least one strain sensor and a temperature sensor, wherein the strain sensor is used for sensing pipeline strain change caused by pipeline pressure change, the temperature sensor is used for measuring the temperature value of the pipeline, and the offset introduced by the strain sensor under the influence of temperature before the dynamic pressure begins is corrected. The embodiment can comprise four strain sensors and four temperature sensors, wherein four groups of strain sensors correspond to temperature input values, 4 groups of strain values can be measured, and abnormal values are eliminated by adopting an abnormal value elimination method (a Grabas criterion/Dixon criterion can be adopted) in order to ensure the accuracy of the pressure output. If there is no abnormal value, the average value of the 4 groups of values is output, and if there is an abnormal value, the average value of the residual pressure values is output. ) The measurement performance of the sensor modules is written into the acquisition and processing memory module when the sensor modules leave a factory, and the static pressure calibration equation and the dynamic analysis data are also written into the acquisition and processing memory module.

The static pressure calibration equation can be obtained by the following procedure:

firstly, obtaining strain and measured temperature T through static verification test_MeasuringPressure corresponding fitting equation:

P＝f₁(ε)+f₂(T_measuring)；

then, static pressure calibration is carried out:

measuring multiple groups of temperature, pressure and strain values at different measuring point positions on the calibration pipeline, and substituting the measured values into a fitting formula P ═ f₁(ε)+f₂(T_Measuring) And respectively obtaining a specific static pressure calibration equation at each measuring point position: p_n＝f_1n(ε)+f_2n(T_Measuring) (ii) a Where P is pressure, ε is strain, T_MeasuringFor actual measurement of temperature, f₁(epsilon) is a pressure versus stress functional relationship; f. of₂(T_Measuring) As a function of pressure and temperature. The calibration pipeline is a pipeline which is obtained in a verification test and is provided with pressure and/or temperature sensors for determining the positions of measuring points and bonding and determining the positions of the measuring points.

The dynamic analysis data are divided into two types, respectively:

a. obtaining the relation between the strain value and the temperature value variation and the corresponding pressure relief rate in the pressure dynamic variation process, namely the variation conditions of the strain and the temperature corresponding to different pressure relief rates;

b. obtaining a pressure value directly calling the static pressure calibration equation to calculate and an actual dynamic standard pressure P_{Sign board}Deviation curve in time domain, wherein actual dynamic standard pressure P_{Sign board}By measuring point positionMeasured by a dynamic pressure sensor; the deviation of the two is used as the influence of the temperature measurement deviation on the pressure at the current pressure relief rate, and the actual temperature T at the pressure relief rate within a certain range is deduced according to the deviation curve_{Practice of}For measured temperature T in the interval_MeasuringCorrection formula f₃(T_Measuring)；

The preparation method specifically comprises the following steps:

fourthly, drawing the pressure value in the third step and the actual dynamic standard pressure P measured by the dynamic pressure measuring sensor under the test of simulating pressure release for a plurality of times_{Sign board}Obtaining a deviation curve of the pressure value calculated by directly calling the static pressure calibration equation and the actual dynamic standard pressure in a time domain, taking the deviation of the pressure value and the actual dynamic standard pressure as the influence of the temperature measurement deviation on the pressure at the current pressure relief rate, and deducing the actual temperature T at the pressure relief rate in a certain range according to the deviation curve_{Practice of}For measured temperature T in the time domain_MeasuringCorrection formula f₃(T_Measuring)。

When a certain set pressure measuring point needs to be measured, the temperature and strain measurement value of the measuring point are directly stored in a data storage card of an acquisition processing memory module, the sampling rate of the acquisition processing memory module is designed in advance to ensure the accuracy of time output, and the conventional setting is 10 Hz. After the dynamic pressure measurement is completed, the dynamic pressure change curve can be analyzed through analysis.

The design block diagram of the acquisition processing memory module is shown in fig. 2. The method is mainly used for data analysis of the dynamic process to obtain a dynamic pressure curve graph of the dynamic pressure process and the pressure value of a single-measuring point at a specified time. The device mainly comprises a signal acquisition unit, a power supply conversion unit, a battery system and an analysis and storage unit which are arranged in a shell. The working principle is shown in fig. 3, and a sensor interface is arranged on the shell; the sensor interface is electrically connected with the analysis and storage unit through the signal acquisition unit; the battery system supplies power to the signal acquisition unit and the analysis and storage unit through the power supply conversion unit;

the signal acquisition unit comprises a plurality of acquisition channels, each acquisition channel comprises an acquisition module, and each acquisition channel corresponds to each sensor in each sensor module one by one; the sensor interface is inserted with a sensor module at the position of a pressure measurement point to be measured, and an acquisition module in a corresponding acquisition channel in the signal acquisition unit converts an acquired signal into a digital signal and sends the digital signal to the analysis and storage unit; the analysis and storage unit is used for analyzing and storing a fitting formula P according to the positions of the corresponding measuring points_n＝f_1n(ε)+f_2n(T_Measuring) Calculating a static pressure value before the dynamic change of the pressure in the pipeline at the position of the measuring point begins; taking the static pressure value as a baseline pressure, setting the change conditions of the strain value and the temperature value in a set time domain in the dynamic pressure change process, and calculating the pressure relief rate in the time period based on the analytic data a of the dynamic pressure calibration test; according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{In fact}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝f_1n(ε)+f_2n(T_{Practice of}) Solving the pressure value of the current time domain; and obtaining the pressure values in all time domains, further obtaining the pressure values in all time domains in the whole dynamic change process, and obtaining the dynamic pressure measurement curve in the whole dynamic change process.

As shown in fig. 4, each group of acquisition modules mainly comprises an 1/4 bridge circuit, an amplifying circuit, a follower circuit and an AD converter. The analog signals of the sensor respectively pass through an 1/4 bridge circuit, an amplifying circuit and an AD converter, and finally the acquired and converted voltage digital quantity is output to a system control unit for processing. Meanwhile, in order to ensure the stability of the sampled data, the 2.5V reference voltage output by the AD converter is used as a voltage reference source of the 1/4 bridge circuit after effective isolation and front-end noise reduction of the follower circuit, as shown in fig. 5. The signal acquisition unit of the embodiment has 5 independent acquisition modules which respectively correspond to the 4-path pressure sensor and the 1-path temperature sensor.

The specific verification test procedure of this example is as follows:

static verification test:

performing verification test by adopting a first material (stainless steel, which is a pipeline to be tested connected with a high-pressure container to be tested) pipeline

The pipeline is put into high low temperature test box, and the one end of pipeline is sealed with the end cap, and another termination standard pressure source, strain sensor and temperature sensor arrange in the different positions of pipeline, through adjusting different temperature, pressure condition, rise, step-down to the pipeline under every test temperature promptly, monitor the temperature variation, wait to record the output of meeting an emergency after the pipeline temperature is stable. Analyzing and calibrating the positions of all measuring points of 0-20 MPa in a temperature environment by using multiple groups of measurement data of temperature, pressure and strain values, and analyzing the corresponding relation P f of strain, temperature and pressure₁(ε)+f₂(T_Measuring) The embodiment is as follows: p ═ a epsilon + bT_Measuring ³+cT_Measuring ²+dT_Measuring+e₁+e₂Wherein a, b, c, d, e₁、e₂Are all constant, and the positions of different measuring points have different a, b, c, d and e₁、e₂A value;

the connection diagram of the verification test is shown in FIG. 6. The test comprises 8 measuring point positions in total, wherein a strain sensor and a temperature sensor are pasted at each measuring point position, a strain signal of the strain sensor is transmitted to a strain measuring instrument through a cable, strain values of different measuring point positions are displayed through different channels of the strain measuring instrument, and a temperature signal of the temperature sensor is transmitted to a temperature measuring instrument through the cable. Since the strain gauge selected in this embodiment has only 6 available channels, only 6 representative measuring point positions among 8 measuring points are selected for the verification test.

The specific conditions are as follows:

(1) temperature measurement points: -30 ℃, 0 ℃, 20 ℃, 40 ℃, 60 ℃ and 75 ℃.

(2) Pressure measurement points: 0MPa, 5MPa, 10MPa, 15MPa, 18MPa, 20 MPa.

(3) A strain sensor: high accuracy strain gauge.

(4) The pasting process comprises the following steps: and (3) treating the adhered surface of the pipeline, adopting an H-600 double-component epoxy resin adhesive to fix and adhere, and drying and curing the pipeline according to the use requirement.

(5) Selecting a pasting position: the two strain sensors are in a group, the four strain sensors are arranged at the top and are designed and adhered, and the strain sensors are respectively distributed on the pipeline according to the axial-radial-axial-radial sequence once according to different strain directions of the measurement pipeline. The sticking mode of the strain sensor is shown in figure 7, in the figure, the axial strain of the strain sensor test pipeline at the measuring point position 1, the measuring point position 2, the measuring point position 5 and the measuring point position 6, and the radial strain of the strain sensor test pipeline at the measuring point position 3, the measuring point position 4, the measuring point position 7 and the measuring point position 8.

(6) Temperature measurement: and a patch type temperature sensor is arranged beside each strain measuring point position and used for measuring the temperature of the measuring point position, and the accuracy grade of the patch type temperature sensor is A grade.

(7) Data output device selection: high accuracy strain gauge.

(8) Line connection: and a circuit board welding mode.

(9) A measurement circuit: a quarter bridge.

Static validation test verification conclusion

Aiming at the pipeline made of stainless steel. Through data analysis, the maximum axial strain is about 96 mu epsilon within the pressure range of 0-20 MPa, the maximum radial (or circumferential) strain is about 370 mu epsilon, and the radial change is about 4 times of the axial change, so that only the radial strain of the pipeline to be tested is tested in a specific calibration measurement test. The radial sensors with obvious changes are taken for data analysis, and test data curves are shown in fig. 8 and fig. 9. CH3 in fig. 8 indicates that the data collected is the data of the 3 rd channel of the strain gauge; CH4 in fig. 9 indicates that data of the 4 th channel of the strain gauge is collected.

It can be seen from fig. 8 and 9 that the strain sensor has good linear consistency at each temperature, and the pressure and strain are linear.

From fig. 10 and fig. 11, it can be known that the strain and the temperature of the strain sensor under the fixed pressure present a curve characteristic, and the relationship can be expressed by a quadratic equation, and the strain sensor has good consistency between the temperature and the strain relationship. By curve fitting, the pressure can be expressed as P ═ a epsilon + bT_{Side survey} ³+cT_Measuring ²+dT_Measuring+e₁+e₂(wherein P is pressure,. epsilon. is strain, and T is temperature). The requirement of measurement precision is met under the conditions of (-30-75) DEG C and (0-20) MPa. The pressure sensor can be used for real-time pressure measurement and monitoring of the pressure vessel.

Through the verification test, an optimal measuring point position is obtained, the measuring point position determined in the embodiment is shown in fig. 12, an arrow represents a strain sensing direction, wherein strain sensors are adhered to the

measuring point positions

1, 2, 3 and 4, the two strain sensors are in one group, the two strain sensors in each group are arranged along the radial top of the pipeline, the two groups of strain sensors are arranged along the axial direction of the pipeline, the radial strain of the pipeline is tested, and the two temperature sensors are adhered to the

measuring point positions

5 and 6.

The specific pressure calibration process and pressure measurement process of this embodiment are as follows:

static pressure calibration process:

taking the verification test pipeline with the corresponding sensor adhered to the optimal measuring point position as a calibration pipeline, and determining calibration conditions in the calibration process, wherein the calibration conditions comprise a temperature measuring point and a pressure measuring point; putting the calibration pipeline into an environment temperature test box for calibrationOne end of the pipeline is sealed by a plug, the other end of the pipeline is connected with a standard pressure source, according to the determined temperature measurement point and strain measurement point, the calibrated pipeline is pressurized to the pressure measurement point under each temperature measurement point aiming at each measurement point position, the temperature is controlled to the corresponding temperature measurement point, the strain output value at each measurement point position is recorded after the pipeline temperature is stable, and according to the corresponding relation P f of the strain, the temperature and the pressure₁(ε)+f₂(T) obtaining a concrete fitting formula P of pressure at each measuring point position with respect to temperature and strain_n＝f_1n(ε)+f_2n(T); and write it to the demodulator module. The embodiment specifically includes: p_n＝a_nε+b_nT³+c_nT²+d_nT+e_1n+e_2nWherein a is_nAnd e_1nIs and K_1nConstant of correlation, b_n、c_n、d_n、e₂Is and K_2nThe associated constant, n, being the number of station positions, e.g. for the first station position, P₁＝a₁ε+b₁T³+c₁T²+d₁T+e₁₁+e₂₁For the second measuring point position, P₂＝a₂ε+b₂T³+c₂T²+d₂T+e₁₂+e₂₂。

Dynamic pressure calibration process:

first, in the initial stage, that is, when the pressure is not yet released, P ═ a ∈ + bT is used according to the strain and temperature value at the measurement point position³+cT²+dT+e₁+e₂Calculating an initial pressure value;

secondly, arranging dynamic pressure measuring sensors at each measuring point of the static verification test pipeline, and performing a test of simulating pressure release every five minutes, wherein the pressure release rate is different every time; in the test process, the temperature in the pressure relief pressure loop can be quickly reduced, the surface temperature cannot be accurately measured under the condition that the inner wall surface and the outer wall surface have large temperature difference (temperature gradient) during temperature measurement, and if P is utilized, a epsilon + bT³+cT²+dT+e₁+e₂If the pressure value is calculated, an error caused by temperature reduction can be brought in; in this embodiment, a dynamic pressure measurement sensor is used to measure the pressure value of the pipeline at the corresponding measurement point, where the pressure value is the actual dynamic standard pressure P_{Sign board}(ii) a Acquiring the variation of the strain value and the temperature value measured by the strain sensor and the temperature sensor at each measuring point position in the process of simulating the pressure release test on the basis of the strain value and the temperature value before the pressure dynamic change starts; establishing a relation between a strain value and a temperature value variable quantity in a pressure dynamic change process and a corresponding pressure release rate; based on P ═ a epsilon + bT_Measuring ³+cT_Measuring ²+dT_Measuring+e₁+e₂Acquiring a pressure value calculated under multiple simulated pressure relief tests; drawing the pressure value of the step (c) and the actual dynamic standard pressure P measured by the dynamic pressure measuring sensor under the condition of simulating the pressure release test for many times_{Sign board}The curves are shown in fig. 13. Wherein, the value measured by the contact sensor is pressure data directly measured by the pressure sensor on the pipeline and is actual dynamic standard pressure P_{Sign board}. The non-contact sensor measures the value of P ═ a epsilon + bT_Measuring ³+cT_Measuring ²+dT_Measuring+e₁+e₂The pressure values obtained after calculation. It can be seen from the figure that there is a certain deviation between them, and the invention considers the deviation between them to be caused by the deviation of the temperature measurement in the pressure relief pressure circuit. In this embodiment, the error of the two pressure release rates is analyzed, and the error analysis is performed on the pressure release process, as shown in fig. 14 and 15, to derive the actual temperature T at a certain range of pressure release rate_{Practice of}For measured temperature T in the interval_MeasuringCorrection formula f₃(T_Measuring)。

Dynamic calibration test verification conclusion

1. The method has feasibility in the dynamic pressure measurement process;

2. the gas cylinder has larger temperature drop in the gas discharging process, the temperature drop is a conduction process from the inner wall to the outer wall of the gas cylinder, so that an error caused by temperature or temperature gradient is caused, and the error caused by the temperature correction caused by temperature parameters in the gas discharging process can be reduced through subsequent experiments.

3. After the deflation is stopped, the temperature in the gas cylinder rises to cause the gas to expand, and the pressure also rises after the abandonment of the deflation is stopped, which is an objective phenomenon.

And (3) a pressure measurement process:

1) connecting a calibration pipeline (excluding a dynamic pressure measurement sensor) in the static pressure calibration process with a high-pressure container, and acquiring the current strain value and temperature value of each measuring point position in a measuring area through a strain sensor and a temperature sensor; the acquisition processing memory module is inserted with a pressure and/or temperature sensor on a calibration pipeline connected with a high-pressure container through a sensor interface, and an acquisition module of a corresponding acquisition channel in the control signal acquisition unit converts an acquired signal into a digital signal and sends the digital signal to the analysis and storage unit;

2) the analysis and storage unit is used for analyzing and storing a fitting formula P ═ a epsilon + bT at the position of the corresponding measuring point_Measuring ³+cT_Measuring ²+dT_Measuring+e₁+e₂Calculating a static pressure value before the dynamic change of the pressure in the pipeline at the position of the measuring point begins;

4) according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{In fact}Will find the actual temperature T_{Practice of}Substituting into the static pressure calibration equation, wherein P is a epsilon + bT_{Practice of} ³+cT_{Practice of} ²+dT_{Practice of}+e₁+e₂Solving the pressure value of the current time domain;

Example two

The measurement system and the specific measurement test in this embodiment are identical to those in the first embodiment, and are different from those in the first embodiment in the static verification test.

The specific verification test of this example is as follows:

in this embodiment, the verification test is performed by using a pipe made of the second material (titanium alloy, which is a pipe to be tested and connected to a high-pressure vessel).

The method specifically connects 8 strain sensors, 2 temperature sensors and their associated display and transmission systems with fig. 6 in the first embodiment, except that the temperature values of the two temperature sensors are used as the temperature values of the positions of 8 measuring points in this embodiment. As shown in fig. 16.

The pipeline is placed in a high-low temperature test box, one end of the pipeline is sealed by a plug, the other end of the pipeline is connected with a standard pressure source, a strain sensor and a temperature sensor are arranged at different positions of the pipeline, the pipeline is pressurized at each test temperature by adjusting different temperature and pressure conditions, the temperature change is monitored, and the strain magnitude is recorded after the temperature of the pipeline is stable. Calibrating all test points of 0-20 MPa in a temperature environment, acquiring data through a temperature measuring instrument and a strain measuring instrument, analyzing the corresponding relation between strain and temperature and pressure, and fitting a binary polynomial of the pressure on the temperature and the strain.

The specific conditions are as follows:

(1) temperature measurement points: -10 ℃, minus 5 ℃, 0 ℃, 10 ℃, 20 ℃ three times, 25 ℃, 30 ℃ and 40 ℃.

(2) Pressure measurement points: 0MPa, 5MPa, 10MPa, 13MPa, 16MPa, 18MPa, 20 MPa.

(3) A strain sensor: high accuracy strain gauge.

(5) Selecting a pasting position: as shown in fig. 16, the positions from measurement point position 1 to measurement point position 8 are strain sensors, and the measurement point positions 9 and 10 are temperature sensors; strain sensor top arrays at a measuring point position 4 and a measuring point position 8, strain sensor top arrays at a measuring point position 1 and a measuring point position 5, and strain sensor top arrays at a measuring point position 3 and a measuring point position 6 are all used for testing the radial strain of the pipeline. And strain sensor heads at the measuring point position 2 and the measuring point position 7 are arranged and used for testing the axial strain of the pipeline.

(6) Temperature measurement: and a patch type temperature sensor is respectively arranged at the measuring point position 9 and the measuring point position 10 and used for measuring the temperature of the measuring point position, and the accuracy grade of the patch type temperature sensor is A grade.

(7) Data output device selection: high accuracy strain gauge.

(8) Line connection: and a circuit board welding mode.

Conclusion of the verification test

Mainly consider the strain changes of different temperatures under the same measuring point position condition and pressure change, and take the measuring point position 8 as an example to analyze.

As shown in FIG. 17, the strain changes at the measurement point positions 8 under pressure changes at different temperatures (-10 ℃ C., -5 ℃ C., 0 ℃ C., 10 ℃ C., 20 ℃ C., three times, 25 ℃ C., 30 ℃ C., 40 ℃ C.) (the average value results show that the strain values under the same pressure at different temperatures are averaged). From the experimental data in the figure, it can be seen that the pressure output is plotted as a cubic curve against the temperature input at constant pressure. P ═ f (T) (data from the current test line show that when T is taken as a cubic function, R is²Approaches to 1, wherein R²Correlation coefficient, R, being the degree of agreement between test data and fitting function²The closer to 1, the higher the degree of coincidence, and the closer to 0, the lower the degree of coincidence. ).

The curve graphs of the change of strain with pressure at the measuring point positions 8 at the temperatures of-10 ℃, 5 ℃, 0 ℃, 10 ℃, 20 ℃ -1 ℃, 20 ℃ -2 ℃, 20 ℃ -3 ℃, 25 ℃, 30 ℃ and 40 ℃ are shown in FIGS. 18-27, wherein the x axis is a pressure value with the unit of MPa, the y axis is a strain value with the unit of mu epsilon, and the mean value trajectory equation at each temperature value is shown in the following table:

as can be seen from fig. 18 to 27, at constant temperature, the pressure output value is linear with the strain input value. P ═ f (epsilon) (when epsilon is a linear function, R²Approaching 1).

In the case of the current test pipeline, the fitting formula of pressure with respect to temperature and strain is as follows: p ═ a epsilon + bT_Measuring ³+cT_Measuring ²+dT_Measuring+e₁+e₂Wherein, a, b, c, d, e₁、e₂Is constant, P is pressure, ε is strain, T_MeasuringTo measure the temperature.

Obtaining a specific fitting formula P at each measuring point position by utilizing a pressure calibration process_n＝a_nε+b_nT_Measuring ³+c_nT_Measuring ²+d_nT_Measuring+e_1n+e_2nAccording to a specific fitting formula P in the measurement experiment_n＝a_nε+b_nT_Measuring ³+c_nT_Measuring ²+d_nT_{Side survey}+e_1n+e_2nAnd calculating the pressure in the pipeline at the current measuring point position, and finally obtaining the current pressure value in the high-pressure container.

The feasibility and the practicability of the measuring method are verified, and a large number of verification tests are performed in the period, wherein the verification tests comprise the following steps: pressure strain, temperature strain, constant temperature pressure strain, repeated constant temperature pressure strain test (oil medium), each verification test is a further proof of the application of the method. The conclusions of each of the preliminary validation tests are summarized below:

1, pressure strain test:

and (3) analyzing test results: test data indicate that changes in line pressure cause changes in line strain that are clearly measurable. The radial variation of the pipeline is more obvious relative to the axial variation. But the strain changes irregularly, and other influence factors exist in preliminary consideration.

2 temperature strain test:

and (3) analyzing test results: from the results of the pressure strain test, it was preliminarily determined that temperature is also an influence quantity affecting the change in strain. Through analysis of experimental data, temperature can cause large strain changes to the pipeline.

3 constant temperature pressure strain test:

and (3) analyzing test results: by carrying out a pressurization strain test in a constant temperature box, when the temperature is constant, the uncertainty of temperature measurement exists, the temperature of a pressurization (nitrogen) pipeline rises sharply, and the strain measurement is carried out when the temperature is constant to be close to a standard temperature, and the measurement result shows that the relation between the pressure and the strain is almost linear under the constant temperature, although a certain deviation exists, the feasibility of the measurement method is shown.

4, repeated constant-temperature pressure strain test:

and (3) analyzing test results: through long-term test exploration, repeated pressure strain tests at different temperatures have data with particularly good linearity and individually deviated measurement data, and the reason for the deviation of the obtained measurement data is that temperature measurement is inaccurately introduced, so that the individual measurement result deviates and certain deviation exists in the linearity after a large amount of test data are analyzed and the conditions of measuring and collecting data are recorded. In order to ensure the accuracy of temperature measurement, the pipeline temperature is ensured to be relatively stable in a measurement state, and the precision of a temperature measuring instrument is improved. And (5) determining the oil pressure test at the later stage, and performing further verification.

5 repeated constant temperature pressure strain test (oil medium) test

And (3) analyzing test results: through long-term repeated test exploration, pressure strain tests are repeatedly carried out at different temperatures, under the condition that temperature measurement data are better guaranteed, a large amount of test data are analyzed, conditions of measurement and data collection are recorded, an obvious linear relation between strain and pressure is obtained, the difference between process data and return data is small, and data output is stable. The feasibility of measuring pressure using strain was further verified. In the next step, the influence of temperature on strain output should be further studied so as to achieve the purpose of accurately measuring pressure.

6 repeated constant pressure strain temperature test

And (3) analyzing test results: through long-term repeated groping tests, temperature strain tests are repeatedly carried out under different pressures, under the condition that pressure measurement data are guaranteed, a large amount of test data are analyzed, conditions of measuring and collecting data are recorded, a regular nonlinear relation between strain and temperature is obtained, the difference between process data and return data is small, and data output is stable.

The above experimental conclusion is the basis for supporting the measuring system formed by the method, and supports the determined fitting formula P ═ a epsilon + bT of the two pipelines which are researched in the calibration test³+cT²+dT+e₁+e₂And the fitting formula P ═ f of other measuring pipelines which are widely applicable to the method₁(ε)+f₂(T)。

Claims

1. A non-contact pressure measurement method based on strain and temperature sensors is characterized by comprising a verification test process, a pressure calibration process and a pressure measurement process:

the verification test process comprises the following steps:

P＝f₁(ε)+f₂(T_{side survey})；

the pressure calibration process comprises the following steps:

1) static pressure calibration:

P_n＝f_1n(ε)+f_2n(T_measuring)

2) dynamic pressure calibration:

a. obtaining the relation between the strain value and the temperature value variation and the corresponding pressure relief rate in the pressure dynamic variation process;

b. obtaining a pressure value directly calling the static pressure calibration equation to calculate and an actual dynamic standard pressure P_{Sign board}Deviation curve in time domain, wherein actual dynamic standard pressure P_SignMeasuring by a dynamic pressure sensor at the position of a measuring point; the deviation of the two is used as the influence of the temperature measurement deviation on the pressure at the current pressure relief rate, and the actual temperature T at the pressure relief rate within a certain range is deduced according to the deviation curve_{Practice of}For measured temperature T in the interval_MeasuringCorrection formula f₃(T_Measuring)；

a sensor interface is arranged on the shell;

the pressure measurement process comprises the following steps:

1) connecting a calibration pipeline in the static pressure calibration process with a high-pressure container, acquiring current strain values and temperature values of each measuring point position in a measuring area through a strain sensor and a temperature sensor, and storing the current strain values and the current temperature values in an acquisition processing memory module of a measuring system;

2) the analysis and storage unit is used for analyzing and storing a fitting formula P according to the positions of the corresponding measuring points_n＝f_1n(ε)+f_2n(T_Measuring) Calculating a static pressure value before the dynamic change of the pressure in the pipeline at the position of the measuring point begins;

4) according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{Practice of}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝f_1n(ε)+f_2n(T_{Practice of}) Solving the pressure value of the current time domain;

2. The strain and temperature sensor-based non-contact pressure measurement method according to claim 1, wherein the static pressure calibration process specifically comprises:

to different measuring points on the calibration pipelinePosition, measuring multiple groups of temperature, pressure and strain values, and substituting into fitting formula P ═ f₁(ε)+f₂(T_Measuring) And respectively obtaining a specific static pressure calibration equation at each measuring point position: p_n＝f_1n(ε)+f_2n(T_Measuring)；

3. The strain, temperature sensor-based non-contact pressure measurement method according to claim 2, wherein the dynamic pressure calibration test specifically comprises the steps of:

fourthly, drawing the pressure value in the third step and the actual dynamic standard pressure P measured by the dynamic pressure measuring sensor under the test of simulating pressure release for a plurality of times_{Sign board}Obtaining a deviation curve of the pressure value calculated by directly calling the static pressure calibration equation and the actual dynamic standard pressure in a time domain, taking the deviation of the pressure value and the actual dynamic standard pressure as the influence of the temperature measurement deviation on the pressure at the current pressure relief rate, and deducing the actual temperature T at the pressure relief rate in a certain range according to the deviation curve_{Practice of}In the inter-domain toMeasured temperature T_MeasuringCorrection formula f₃(T_{Side survey})。

4. The method of claim 2, wherein the strain and temperature T is measured for a pipe made of two materials, stainless steel and titanium alloy_MeasuringThe corresponding fitting formula of the pressure is as follows:

P＝aε+bT_measuring ³+cT_Measuring ²+dT_Measuring+e₁+e₂

P_n＝a_nε+b_nT_measuring ³+c_nT_Measuring ²+d_nT_Measuring+e_1n+e_2n

Wherein a is_nAnd e_1nIs and K_1nConstant of correlation, b_n、c_n、d_n、e₂Is and K_2nA related constant, n is a measuring point position serial number;

the pressure measurement process, step 5) is specifically:

according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{Practice of}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝a_nε+b_nT_{Practice of} ³+c_nT_{Practice of} ²+d_nT_{Practice of}+e_1n+e_2nAnd solving the pressure value of the current time domain.

5. The method of claim 4, wherein the static proof test procedure is:

P＝f₁(ε)+f₂(T_measuring)；

6. The method for non-contact pressure measurement based on strain and temperature sensor as claimed in claim 5, wherein the static verification test process is specifically as follows:

7. The strain, temperature sensor-based non-contact pressure measurement method according to claim 6, wherein the static pressure calibration process specifically comprises the steps of:

step 1d, according to the temperature measurement points and the strain measurement points determined in the step 1b, aiming at the positions of each measurement point, pressurizing the calibration pipeline to a pressure measurement point under each temperature measurement point, controlling the temperature to the corresponding temperature measurement point, recording the strain output value at the position of each measurement point after the pipeline temperature is stable, and according to the corresponding relation P (f) of the strain, the temperature and the pressure₁(ε)+f₂(T_{Side survey}) Obtaining a concrete fitting formula P of the pressure at the position of each measuring point with respect to the temperature and the strain_n＝f_1n(ε)+f_2n(T_Measuring)。

8. The method of claim 7, wherein the strain-temperature sensor-based non-contact pressure measurement is performed by: the method comprises the following steps that (1) at least one measuring point position is determined through a verification test, and a strain sensor and a temperature sensor are pasted at the measuring point position; the strain sensor is used for testing the radial strain quantity of the pipeline.

9. The method of claim 7, wherein the strain-temperature sensor-based non-contact pressure measurement is performed by: the verification test determines 6N measuring point positions which are divided into N areas; in each area, strain sensors are pasted at four measuring point positions, and temperature sensors are pasted at the other two measuring point positions; and two strain sensors are in a group, two strain sensors in each group are arranged along the radial top of the pipeline, and two groups of strain sensors are arranged along the axial direction of the pipeline to test the radial strain of the pipeline.

10. A non-contact pressure measurement system based on strain and temperature sensors is characterized in that: comprises a sensor module and an acquisition processing memory module;

the acquisition processing memory module is used for acquiring and storing the measurement data of the sensor module and simultaneously storing a specific static pressure calibration equation P of each measuring point position_n＝f_1n(ε)+f_2n(T_Measuring) And storing analytical data a and b obtained in the dynamic pressure calibration process; and based on the collected sensor module measurement data, according to a fitting formula P at the position of the corresponding measuring point_n＝f_1n(ε)+f_2n(T_Measuring) Calculating a static pressure value before the dynamic change of the pressure in the pipeline at the position of the measuring point begins; taking the static pressure value as a baseline pressure, setting the change conditions of the strain value and the temperature value in a time domain by analyzing the dynamic change process of the pressure, and calculating the pressure relief rate in the time domain based on the analytic data a of the dynamic pressure calibration test; according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{Practice of}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝f_1n(ε)+f_2n(T_{Practice of}) Solving the pressure value of the current time domain; and obtaining the pressure values in all time domains, further obtaining the pressure values in all time domains in the whole dynamic change process, and obtaining the dynamic pressure measurement curve in the whole dynamic change process.

11. The strain, temperature sensor-based non-contact pressure measurement system of claim 10, wherein: the acquisition processing memory module comprises a shell, and a signal acquisition unit, a power supply conversion unit, a battery system and an analysis and storage unit which are arranged in the shell;

a sensor interface is arranged on the shell;

the sensor interface is inserted with a sensor module at the position of a pressure measurement point to be measured, and an acquisition module in a corresponding acquisition channel in the signal acquisition unit converts an acquired signal into a digital signal and sends the digital signal to the analysis and storage unit; the analysis and storage unit is used for analyzing and storing a fitting formula P according to the positions of the corresponding measuring points_n＝f_1n(ε)+f_2n(T_Measuring) Calculating a static pressure value before the dynamic change of the pressure in the pipeline at the position of the measuring point begins; taking the static pressure value as a baseline pressure, setting the change conditions of the strain value and the temperature value in a time domain by analyzing the dynamic change process of the pressure, and calculating the pressure relief rate in the time domain based on the analytic data a of the dynamic pressure calibration test; according to the pressure relief rate, the actual temperature T is calculated based on the analytic data b of the dynamic pressure calibration test_{Practice of}Will find the actual temperature T_{Practice of}Substitution into the static pressure calibration equation, P_n＝f_1n(ε)+f_2n(T_{Practice of}) Solving the pressure value of the current time domain; and obtaining the pressure values in all time domains, further obtaining the pressure values in all time domains in the whole dynamic change process, and obtaining the dynamic pressure measurement curve in the whole dynamic change process.

12. The strain, temperature sensor-based non-contact pressure measurement system of claim 11, wherein: each group of acquisition modules comprises an 1/4 bridge circuit, an amplifying circuit, a following circuit and an AD converter; the analog signal of the sensor passes through an 1/4 bridge circuit, an amplifying circuit and an AD converter, and finally the analog signal is converted into a voltage digital quantity to be output to a system control unit for processing; the 2.5V reference voltage output by the AD converter is used as a voltage reference source of an 1/4 bridge circuit after effective isolation and front-end noise reduction of the follower circuit.