CN116465539A - Fiber bragg grating liquid pressure measuring device and method - Google Patents
Fiber bragg grating liquid pressure measuring device and method Download PDFInfo
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- 239000000806 elastomer Substances 0.000 claims abstract description 64
- 238000002955 isolation Methods 0.000 claims abstract description 49
- 238000009530 blood pressure measurement Methods 0.000 claims abstract description 16
- 230000005540 biological transmission Effects 0.000 claims abstract description 15
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- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L7/00—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements
- G01L7/02—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges
- G01L7/026—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges with optical transmitting or indicating means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
- G01L11/02—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means
- G01L11/025—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means using a pressure-sensitive optical fibre
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L7/00—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements
- G01L7/02—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges
- G01L7/028—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges correcting or regulating means
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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- Measuring Fluid Pressure (AREA)
Abstract
The invention discloses a fiber bragg grating liquid pressure measuring device and a method, which relate to the technical field of liquid pressure sensors and comprise a shell, a first fiber bragg grating component and a second fiber bragg grating component; the first fiber bragg grating assembly comprises a first isolation component, a first force transmission assembly, a first beam-type elastomer, a first fiber bragg grating sensor and a second fiber bragg grating sensor; a liquid containing cavity is formed between the first isolation part and the second isolation part; the end face of the first isolation part far away from the liquid containing cavity is provided with a first force conduction component; the end face of the first force transmitting assembly distal from the first isolation member being adjacent to the end face of the first beam-type elastomer; the first fiber bragg grating sensor and the second fiber bragg grating sensor are symmetrically arranged on two end faces of the first beam-type elastomer; the second fiber bragg grating component has the same structure as the first fiber bragg grating component. The invention achieves the effects of high pressure measurement precision, strong electromagnetic interference resistance and stable operation.
Description
Technical Field
The invention relates to the technical field of liquid pressure sensors, in particular to a fiber bragg grating liquid pressure measuring device and a fiber bragg grating liquid pressure measuring method.
Background
The hydraulic pressure is a main parameter reflecting the working condition of the hydraulic pipeline and relates to the function of the whole hydraulic system. The working pressure of the hydraulic system of the test bed is monitored in real time in a certain project, the working pressure is carried out under the condition of the test environment temperature (25+/-10), the working medium is aviation hydraulic oil, the working pressure range of the hydraulic system is 0-28MPa, and the temperature of the working medium is allowed to be increased by 10 ℃ than the environment temperature.
The pressure measurement of the hydraulic pipeline at the present stage is mainly a mechanical pressure sensor and an electrical pressure sensor. The mechanical pressure sensor usually takes a mechanical structural member as a main part, but the measurement point is single, the real-time transmission of data cannot be carried out, and the long-term real-time monitoring of the pressure of the hydraulic pipeline cannot be realized. The electrical pressure sensor generally adopts a resistor, a capacitor and the like as pressure sensitive elements, but the output of the pressure sensor is usually voltage and current signals, which are extremely easy to be influenced by electromagnetic interference and can influence the pressure measurement accuracy. And under the abominable operational environment of monitoring oil circuit pipeline hydraulic pressure, there is great security risk. In the field of fiber bragg grating liquid pressure transmission, there are many different kinds of products, and common fiber bragg grating liquid pressure monitoring methods are for example, polymer encapsulated fiber bragg grating pressure sensors, elastic sheet encapsulated fiber bragg grating pressure sensors and thin-wall cylinder encapsulated fiber bragg grating pressure sensors.
(1) Polymer encapsulated fiber grating pressure sensor: the polymer for the fiber grating is generally encapsulated in a thick-wall round through, and the fiber grating is driven to deform by utilizing the driving action of the polymer substrate so as to improve the pressure sensitivity of the fiber grating. The fiber grating is packaged in the organic polymer substrate, the packaging technology changes the relative sizes of the pressure and temperature sensitivity of the fiber grating, and the sensitivity of the fiber grating to pressure is improved. However, the fiber grating pressure sensor has the problem of temperature cross sensitivity, the change of external temperature can have a certain influence on the measurement of pressure, but the fiber grating is easily influenced by the cross coupling of strain and temperature, so that the temperature compensation is necessary in the pressure measurement process.
(2) An elastic sheet packaged fiber grating pressure sensor: the fiber bragg grating is packaged in the cylindrical cavity, and deformation caused by pressure response is directly converted into axial strain of the fiber bragg grating through a plane circular sheet, so that high-sensitivity pressure signal detection is realized. The FBG (FiberBragg Grating ) is stretched and converted into the change of the central reflection wavelength of the FBG by the elasto-optical effect of the FBG, so that the high-sensitivity signal detection is realized. Wherein, because the fiber grating is packaged in the cylinder cavity, the temperature in the cavity changes slowly along with the change of the environment. The influence of temperature change on sensing is mainly that the cylindrical shell is linearly expanded by thermal effect, so that the physical length and the modulation period of the fiber bragg grating are changed, the center wavelength drift is caused, and the temperature change has a certain influence on pressure measurement.
(3) Thin-wall cylinder packaged fiber grating pressure sensor: the fiber bragg grating is radially stuck in the V-shaped groove in the middle of the thin-wall cavity, the strain cylinder is strained in the axial direction and the radial direction when being stressed, and the axial strain drives the deformation of the fiber bragg grating, so that the pressure signal detection is realized. The strain cylinder will be strained in axial and radial directions when being stressed, and a V-shaped fixing groove is specially processed on the wall of the pressure measuring tube to tightly combine the grating with the pressure measuring tube and avoid the problem of increasing the thickness of the pressure sensing section tube caused by directly grooving the outer wall of the tube. When the sensor is packaged, the strain grating is adhered in the V-shaped groove in the middle of the thin-wall cavity along the radial direction, the temperature compensation grating is adhered at the thick wall of the tail end of the sensor, but the deformation of the thin-wall cylinder and the deformation of the passive temperature compensation sleeve formed by two materials restrict the wavelength change of the fiber grating together, and different materials have different thermal expansion coefficients, so that the uncertainty error of the structure is larger, and the sensitivity is not high enough.
Disclosure of Invention
The invention aims to provide a fiber bragg grating liquid pressure measuring device and method, which achieve the effects of high pressure measuring precision, strong electromagnetic interference resistance and stable operation.
In order to achieve the above object, the present invention provides the following solutions:
the fiber bragg grating liquid pressure measuring device comprises a shell, a first fiber bragg grating component and a second fiber bragg grating component; the first fiber bragg grating component and the second fiber bragg grating component are both arranged in the shell;
the first fiber bragg grating assembly comprises a first isolation component, a first force transmission assembly, a first beam-type elastomer, a first fiber bragg grating sensor and a second fiber bragg grating sensor; the second fiber bragg grating assembly comprises a second isolation part, a second force transmission assembly, a second beam-type elastomer, a third fiber bragg grating sensor and a fourth fiber bragg grating sensor;
a liquid containing cavity is formed between the first isolation part and the second isolation part; the end surface of the first isolation component far away from the liquid containing cavity is provided with the first force conduction component; an end face of the first force conduction assembly remote from the first isolation member is adjacent an end face of the first beam-type elastomer; the first fiber bragg grating sensor and the second fiber bragg grating sensor are symmetrically arranged on two end faces of the first beam-type elastomer, and the second fiber bragg grating sensor and the first force transmission component are positioned on the same side of the first beam-type elastomer;
the second fiber bragg grating component has the same structure as the first fiber bragg grating component;
when the device works, the liquid to be detected is contained in the liquid containing cavity, under the pressure action of the liquid to be detected, the first isolating part drives the first force conduction assembly to move towards the first beam-type elastomer, and meanwhile, the second isolating part drives the second force conduction assembly to move towards the second beam-type elastomer; the first force conduction component applies acting force to the first beam-type elastomer, so that the first beam-type elastomer deforms and drives the first fiber grating sensor and the second fiber grating sensor to deform; and the second force conduction assembly applies acting force to the second beam elastic body, so that the second beam elastic body deforms and drives the third fiber bragg grating sensor and the fourth fiber bragg grating sensor to deform.
Optionally, the first force conduction assembly comprises a first wedge and a first hemisphere;
the first wedge body is arranged on the end face of the first isolation part, which is far away from the liquid containing cavity; the first hemispherical body is arranged on the end face of the first wedge body, which is far away from the first isolation component, and the arc-shaped surface of the first hemispherical body is adjacent to the end face of the first beam-type elastomer.
Optionally, the first beam-like elastomer includes a fixed end and a free end;
the fixed end is fixedly arranged on the shell, and the free end is adjacent to the arc-shaped surface of the first hemispherical body;
when the acting force exerted by the first hemispherical body is not received, the plane of the fixed end and the free end is perpendicular to the surface of the shell; the free end moves when subjected to the force exerted by the first hemisphere.
Optionally, the first fiber grating assembly further includes a first stopper, a second stopper, and a third stopper;
the first limiting block is arranged on one side, far away from the first force conduction component, of the first beam-type elastomer, and the first limiting block is used for limiting the moving distance of the free end of the first beam-type elastomer;
the second limiting block and the third limiting block are arranged in the liquid containing cavity, the second limiting block and the third limiting block are positioned on the same plane, and the plane where the second limiting block and the third limiting block are positioned is parallel to the end face of the first isolation part; the second limiting block and the third limiting block are used for limiting the first isolation component to move towards the liquid containing cavity.
Optionally, a threaded damping hole is formed in the shell; the thread damping hole is used for injecting liquid to be detected into the liquid containing cavity.
Optionally, the first fiber grating assembly further comprises a first seal end cap;
the first seal end cap is disposed on a side of the first beam elastomer remote from the first force transmitting assembly.
In order to achieve the above purpose, the present invention also provides the following technical solutions:
the method for measuring the liquid pressure of the fiber bragg grating is applied to a device for measuring the liquid pressure of the fiber bragg grating, and comprises the following steps:
acquiring the force load sensitivity on the first beam elastomer and the sectional area of the first isolation component;
after the liquid to be measured is contained in the liquid containing cavity, acquiring the total wavelength drift of the first fiber bragg grating sensor, the total wavelength drift of the second fiber bragg grating sensor, the total wavelength drift of the third fiber bragg grating sensor and the total wavelength drift of the fourth fiber bragg grating sensor;
calculating a first acting force according to the total wavelength drift of the first fiber bragg grating sensor, the total wavelength drift of the second fiber bragg grating sensor, the total wavelength drift of the third fiber bragg grating sensor, the total wavelength drift of the fourth fiber bragg grating sensor and the force load sensitivity on the first beam-type elastomer; the first acting force is acting force applied to the first beam-type elastic body under the pressure action of liquid to be detected in the liquid containing cavity;
calculating a liquid pressure value according to the first acting force and the sectional area of the first isolation component; the liquid pressure value is the pressure value of the liquid to be measured in the liquid containing cavity.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention discloses a fiber bragg grating liquid pressure measuring device and a method, wherein a liquid containing cavity is formed between a first isolation part and a second isolation part, and liquid to be measured is contained in the liquid containing cavity, so that a liquid medium to be measured is completely isolated from a fiber bragg grating, the fiber bragg grating is prevented from being in a severe working environment of high pressure, high temperature and strong corrosion, and the working stability and the service life of a sensor are improved. Under the pressure action of the liquid to be tested, the first isolation part drives the first force conduction assembly to move towards the first beam-type elastomer, and the second isolation part simultaneously drives the second force conduction assembly to move towards the second beam-type elastomer; the first force conduction assembly applies acting force to the first beam-type elastomer, so that the first beam-type elastomer deforms and drives the first fiber grating sensor and the second fiber grating sensor to deform; the second force conduction assembly applies acting force to the second beam-type elastic body, so that the second beam-type elastic body deforms and drives the third fiber bragg grating sensor and the fourth fiber bragg grating sensor to deform; the invention adopts the combination of the fiber grating and the special pressure conversion structure to convert the liquid pressure into the fiber grating wavelength change, and has the characteristics of high pressure measurement precision and strong electromagnetic interference resistance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a fiber grating liquid pressure measuring device according to the present invention;
FIG. 2 is a schematic flow chart of the method for measuring the liquid pressure of the fiber grating according to the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In order to overcome the influence of external electromagnetic interference on pressure measurement and meet the requirement of wide-range high-precision pressure monitoring, the research of a liquid pressure transmitting device with wide monitoring range and high precision is very important in the field of pressure monitoring of hydraulic pipelines. Based on the problems of wide liquid pressure monitoring range, high precision, electromagnetic interference resistance and the like of the liquid pressure monitoring and real-time liquid pressure monitoring range are solved.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
As shown in fig. 1, the invention provides a fiber bragg grating liquid pressure measuring device, which comprises a shell, a first fiber bragg grating component and a second fiber bragg grating component; the first fiber bragg grating component and the second fiber bragg grating component are both arranged in the shell.
The first fiber bragg grating assembly comprises a first isolation component, a first force transmission assembly, a first beam-type elastomer BE1, a first fiber bragg grating sensor FBG1 and a second fiber bragg grating sensor FBG2; the second fiber bragg grating assembly comprises a second isolation component, a second force conduction assembly, a second beam-type elastomer BE2, a third fiber bragg grating sensor FBG3 and a fourth fiber bragg grating sensor FBG4. The specific internal structure of the second fiber bragg grating component is the same as that of the first fiber bragg grating component.
A liquid containing cavity VC1 is formed between the first isolation component and the second isolation component; the end surface of the first isolation component far away from the liquid containing cavity VC1 is provided with the first force conduction component; an end face of the first force conduction assembly remote from the first isolation member is adjacent to an end face of the first beam-type elastomer BE 1; the first fiber bragg grating sensor FBG1 and the second fiber bragg grating sensor FBG2 are symmetrically arranged on two end faces of the first beam-type elastic body BE1, and the second fiber bragg grating sensor FBG1 and the first force transmission component are located on the same side of the first beam-type elastic body BE 1. The optical fiber grating sensors FBG1 and FBG2 are symmetrically fixed on the beam type elastic body BE1, so that the load sensitivity can BE doubled, and measurement errors caused by the influence of temperature on the optical fiber grating FBG1 and FBG2 can BE counteracted. The same applies to the second fiber grating assembly.
In a specific embodiment, the first isolation component and the second isolation component are miniature pistons, and correspond to the miniature pistons MP1 and MP2 in fig. 1, so as to isolate the liquid to be tested from the force transmission component, the beam-type elastomer and the grating fiber sensor, avoid the fiber grating from being in a severe working environment of high pressure, high temperature and strong corrosion, and be favorable for improving the working stability and the service life of the sensor.
A threaded damping hole DH1 is formed in the shell; the thread damping hole DH1 is used for guiding the liquid containing cavity VC1 is filled with liquid to be measured. The liquid injected into the liquid containing cavity VC1 is communicated with the threaded damping hole DH1 under the action of the liquid pressure, so the liquid pressure P of the liquid containing cavity VC1 2 And the liquid pressure value P to be measured 1 Maintain the same (i.e. P 2 ＝P 1 )。
The first force transmission assembly comprises a first wedge-shaped body and a first hemispherical body, wherein the first wedge-shaped body is a first wedge-shaped steel body WS1, and the first hemispherical body is a first hemispherical steel body HE1; the first wedge body is arranged on the end face of the first isolation part, which is far away from the liquid containing cavity; the first hemispherical body is arranged on the end face of the first wedge body, which is far away from the first isolation component, and the arc-shaped surface of the first hemispherical body is adjacent to the end face of the first beam-type elastomer. The second wedge-shaped steel body WS2 and the second hemispherical steel body HE2 in the second fiber bragg grating assembly are similar.
The first beam-type elastic body BE1 includes a fixed end BE11 and a free end BE12; the fixed end BE11 is fixedly arranged on the shell, and the free end BE12 is adjacent to the arc-shaped surface of the first hemispherical body; when the force exerted by the first hemispherical body is not exerted, the plane of the fixed end BE11 and the free end BE12 is perpendicular to the surface of the shell; the free end BE12 moves when subjected to the force exerted by the first hemisphere. Further, the fixed end is the lower end, and the free end is the upper end.
In addition, since the first fiber grating sensor FBG1 and the second fiber grating sensor FBG2 are fixed to the first beam type elastic body BE1, and the third fiber grating sensor FBG3 and the fourth fiber grating sensor FBG4 are fixed to the second beam type elastic body BE2, the deformation of the fiber grating sensors FBG1, FBG2, FBG3 and FBG4 is determined by the beam type elastic bodies BE1 and BE2, and the beam type elastic bodies BE1 and BE2 can BE changed by adjusting the physical dimensions of the beam type elastic bodies. Therefore, the fiber grating sensors FBG1, FBG2, FBG3, FBG4 can be adapted to a wide range of pressure detection by adjusting the physical dimensions of the beam-type elastomer. The liquid pressure conversion element adopts a fiber grating sensor, so that the pressure measurement device has the characteristic of good electromagnetic interference resistance.
Preferably, the length of the fiber grating sensors FBG1, FBG2 is smaller than the length of the first beam-like elastomer BE1, so that the force transmission assembly does not squeeze the fiber grating sensors FBG1, FBG2 when in contact with the first beam-like elastomer BE1, without affecting the measurement data of the fiber grating sensors FBG1, FBG2.
In one embodiment, after the liquid to be measured fills the liquid containing chamber VC1, the micro piston MP1 is at the liquid pressure P of the liquid containing chamber VC1 2 Moves toward the beam type elastic body BE1 under the action of the spring; because the wedge-shaped steel body WS1 is fixedly connected with the miniature piston MP1, the hemispherical steel body HE1 is fixedly connected with the wedge-shaped steel body WS1, so that the hemispherical steel body HE1, the wedge-shaped steel body WS1 and the miniature piston MP1 keep the same direction movement; when the hemispherical steel body HE1 contacts the beam type elastomer BE1, the liquid pressure P in the liquid containing cavity VC1 2 Is applied with force F 21 At the free end BE12 of the beam-type elastomer BE1, F 21 The calculation formula is as follows:
wherein S is MP1 Is the sectional area of the micro piston MP 1. At the acting force F 21 The beam type elastic body BE1 deforms under the action of the sensor, and the fiber bragg grating sensors FBG1 and FBG2 are driven to deform accordingly. Since the fiber grating sensors FBG1, FBG2 are symmetrically fixed on the beam type elastic body BE1, the force F is applied 21 Under the action of the (2), the fiber grating sensor (FBG 1) is compressed, and the FBG2 is stretched, so that the grating wavelengths of the fiber grating sensor (FBG 1) and the FBG 2) are changed as shown in the following formula:
Δλ FBG1 ＝-k F21 F 21 +k T ΔT；
Δλ FBG2 ＝k F21 F 21 +k T ΔT；
wherein Deltalambda FBG1 、Δλ FBG2 Representing the total wavelength drift, k, of the fiber bragg grating sensors FBG1, FBG2 due to deformation and temperature changes F21 The FBG1 and FBG2 of the fiber bragg grating sensor are fixed on beam type elasticityForce load sensitivity on body BE 1; k (k) T The temperature sensitivity of the fiber bragg grating sensors FBG1 and FBG2 indicates wavelength drift caused by temperature changes of the fiber bragg grating sensors FBG1 and FBG2; Δt is the change in the operating temperature of the fiber bragg grating sensors FBG1, FBG2, and represents the wavelength shift caused by the temperature change of the fiber bragg grating sensors FBG1, FBG2; the "-" indicates that the FBG1 is compressed and the "+" FBG2 is stretched, and the fiber grating sensors FBG1 and FBG2 are the same type sensor and are symmetrically fixed to the beam type elastic body BE1, so that the force load sensitivity and the temperature sensitivity are the same. The relationship between the difference of the center wavelengths of the two fiber grating sensors FBG1, FBG2 and the load force is as follows:
Δλ FBG2 -Δλ FBG1 ＝2k F21 F 21 ；
wherein Deltalambda can be measured by a grating demodulator FBG1 And delta lambda FBG2 Further, the difference value of the center wavelengths of the fiber bragg grating sensors FBG1 and FBG2 and F are calculated 21 。
Similarly, in the second fiber grating assembly, the liquid pressure P in the liquid containing cavity VC1 2 Is applied with force F 22 On the beam-type elastomer BE2, F 22 The calculation formula of (2) is as follows:
wherein S is MP2 Is the sectional area of the miniature piston MP 2; the miniature pistons MP1 and MP2 are made of the same material and have the same physical dimensions, so that the sectional areas of MP1 and MP2 are the same, namely S MP2 ＝S MP1 Therefore BE2 and BE1 are subjected to the same pressure, i.e. F 22 ＝F 21 。
The wavelength changes delta lambda of the fiber bragg grating sensors FBG3, FBG4 are measured by a grating demodulator FBG3 And delta lambda FBG4 The relationship between the difference in the center wavelengths of the two fiber grating sensors FBG3, FBG4 and the load force is shown as follows:
Δλ FBG3 -Δλ FBG4 ＝2k F22 F 22 ；
wherein k is F22 For the force load sensitivity of the fiber bragg grating sensors FBG3, FBG4 fixed on the beam type elastic body BE2, the force F is applied 22 Under the influence of (1) the fiber grating sensor FBG3 is stretched and the fiber grating sensor FBG4 is compressed.
As the beam type elastic bodies BE1 and BE2 are made of the same material and have the same physical size, and the fiber grating sensors FBG1, FBG2, FBG3 and FBG4 are made of the same model, the force load sensitivity k on the beam type elastic body BE2 is high F22 Sensitivity k to force load on beam elastomer BE1 F11 Identical, i.e. k F22 ＝k F11 The method comprises the steps of carrying out a first treatment on the surface of the And because BE2 and BE1 are subjected to the same pressure, namely F 22 ＝F 21 The method comprises the steps of carrying out a first treatment on the surface of the The method can be deduced that:
Δλ FBG2 -Δλ FBG1 +Δλ FBG3 -Δλ FBG4 ＝4k F21 F 21 。
f can be obtained by calculation according to the above formula 21 Then from P 2 ＝F 21 ×S MP1 Obtaining the liquid pressure P of the liquid containing cavity VC1 2 From the liquid pressure P of the analysis liquid-holding chamber VC1 2 With the pressure P of the liquid to be measured 1 Maintain the same, i.e. P 2 ＝P 1 Obtaining the pressure P of the liquid to be measured 1 The structure that the grating sensors FBG1 and FBG2 are symmetrically fixed on the beam type elastic body BE1 and the structure that the grating sensors FBG3 and FBG4 are symmetrically fixed on the beam type elastic body BE2 can not only improve the load sensitivity by times, but also offset measurement errors caused by the influence of the temperature on the fiber gratings FBG1, FBG2, FBG3 and FBG4.
Preferably, the first fiber bragg grating assembly further comprises a first limiting block LB1, a second limiting block LB2 and a third limiting block LB3; the first limiting block LB1 is arranged on one side, far away from the first force transmission component, of the first beam-type elastomer BE1, and the first limiting block LB1 is used for limiting the moving distance of the free end of the first beam-type elastomer VE1, so that the fiber grating sensors FBG1 and FBG2 are prevented from being overloaded due to overlarge deformation of BE1 and BE2 caused by overpressure, and the fiber grating liquid pressure transmitting device is beneficial to ensuring normal operation. And a fourth limiting block LB4 in the second fiber bragg grating component is similar.
The second limiting block LB2 and the third limiting block LB3 are arranged in the liquid containing cavity, the second limiting block LB2 and the third limiting block LB3 are positioned on the same plane, and the plane where the second limiting block LB2 and the third limiting block LB3 are positioned is parallel to the end face of the first isolation component; the second limiting block LB2 and the third limiting block LB3 are configured to limit the movement of the first isolation component to the liquid containing cavity, and specifically limit the movement of the micro piston MP1 to the liquid containing cavity VC 1. The fifth limiting block LB5 and the sixth limiting block LB6 in the second fiber grating component are similar.
The first fiber bragg grating assembly further comprises a first sealing end cover EC1; the first seal end cap EC1 is disposed on a side of the first beam-type elastomer BE1 remote from the first force-conducting assembly. Specifically, the first fiber bragg grating component is located at one side far away from the first beam-type elastomer, so that the fiber bragg grating sensors FBG1 and FBG2 are isolated from the external environment, and the fiber bragg gratings FBG1 and FBG2 are protected from dust. And the same applies to a second sealing end cover EC2 in the second fiber bragg grating assembly.
In summary, in the present invention, the liquid to be measured is contained in the liquid containing cavity, under the pressure action of the liquid to be measured, the first isolating component drives the first force conducting component to move towards the first beam-type elastomer, and simultaneously, the second isolating component drives the second force conducting component to move towards the second beam-type elastomer; the first force conduction component applies acting force to the first beam-type elastomer, so that the first beam-type elastomer deforms and drives the first fiber grating sensor and the second fiber grating sensor to deform; and the second force conduction assembly applies acting force to the second beam elastic body, so that the second beam elastic body deforms and drives the third fiber bragg grating sensor and the fourth fiber bragg grating sensor to deform. The fiber bragg grating liquid pressure measuring device realizes a wide pressure measuring range and high pressure measuring precision, and meanwhile, the pressure transmitting device has the characteristic of high electromagnetic interference resistance, and has important application value and practicability in a liquid pipe network pressure monitoring system. The fiber bragg grating sensor can be guaranteed to work in a rated pressure range through the structural design of the limit stop, and damage to the beam type elastomer and the fiber bragg grating sensor is avoided.
As shown in fig. 2, a specific embodiment of the present invention further provides a method for measuring a liquid pressure of an optical fiber grating, which is applied to the device for measuring a liquid pressure of an optical fiber grating, where the method includes:
step 100, obtaining a force load sensitivity on a first beam elastomer and a cross-sectional area of a first isolation assembly.
Step 200, after the liquid to be measured is contained in the liquid containing cavity, the total wavelength drift of the first fiber bragg grating sensor, the total wavelength drift of the second fiber bragg grating sensor, the total wavelength drift of the third fiber bragg grating sensor and the total wavelength drift of the fourth fiber bragg grating sensor are obtained.
Step 300, calculating a first acting force according to the total wavelength drift of the first fiber bragg grating sensor, the total wavelength drift of the second fiber bragg grating sensor, the total wavelength drift of the third fiber bragg grating sensor, the total wavelength drift of the fourth fiber bragg grating sensor and the force load sensitivity on the first beam-type elastomer; the first acting force is acting force applied to the first beam-type elastic body under the pressure action of liquid to be detected in the liquid containing cavity.
Step 400, calculating a liquid pressure value according to the first acting force and the sectional area of the first isolation component; the liquid pressure value is the pressure value of the liquid to be measured in the liquid containing cavity.
The calculation formula of the first acting force is as follows:
Δλ FBG2 -Δλ FBG1 +Δλ FBG3 -Δλ FBG4 ＝4k F21 F 21 ；
wherein Deltalambda FBG1 Representing the total wavelength drift of the first fiber grating sensor, i.e. the total wavelength drift of the fiber grating sensor FBG1 caused by deformation and temperature change, Δλ FBG2 Representing the total wavelength drift of the second fiber bragg grating sensor, namely the total wavelength drift delta caused by the deformation and temperature change of the fiber bragg grating sensor FBG2λ FBG3 Representing the total wavelength drift of the third fiber grating sensor, i.e. the total wavelength drift of the fiber grating sensor FBG3 caused by deformation and temperature change, Δλ FBG4 Representing the total wavelength drift of the fourth fiber bragg grating sensor, i.e. the total wavelength drift, k, of the fiber bragg grating sensor FBG4 due to deformation and temperature changes F21 Representing the sensitivity of force load on the first beam elastomer, F 21 Representing the first force.
The calculation formula of the liquid pressure value is as follows:
P 2 ＝F 21 ×S MP1 ；
wherein F is 21 Representing the first force, P 2 Representing the liquid pressure value, S MP1 The cross-sectional area of the first isolation assembly, i.e., the cross-sectional area of the micro piston MP1, is shown.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (9)
1. The device is characterized by comprising a shell, a first fiber bragg grating component and a second fiber bragg grating component; the first fiber bragg grating component and the second fiber bragg grating component are both arranged in the shell;
the first fiber bragg grating assembly comprises a first isolation component, a first force transmission assembly, a first beam-type elastomer, a first fiber bragg grating sensor and a second fiber bragg grating sensor; the second fiber bragg grating assembly comprises a second isolation part, a second force transmission assembly, a second beam-type elastomer, a third fiber bragg grating sensor and a fourth fiber bragg grating sensor;
a liquid containing cavity is formed between the first isolation part and the second isolation part; the end surface of the first isolation component far away from the liquid containing cavity is provided with the first force conduction component; an end face of the first force conduction assembly remote from the first isolation member is adjacent an end face of the first beam-type elastomer; the first fiber bragg grating sensor and the second fiber bragg grating sensor are symmetrically arranged on two end faces of the first beam-type elastomer, and the second fiber bragg grating sensor and the first force transmission component are positioned on the same side of the first beam-type elastomer;
the second fiber bragg grating component has the same structure as the first fiber bragg grating component;
when the device works, the liquid to be detected is contained in the liquid containing cavity, under the pressure action of the liquid to be detected, the first isolating part drives the first force conduction assembly to move towards the first beam-type elastomer, and meanwhile, the second isolating part drives the second force conduction assembly to move towards the second beam-type elastomer; the first force conduction component applies acting force to the first beam-type elastomer, so that the first beam-type elastomer deforms and drives the first fiber grating sensor and the second fiber grating sensor to deform; and the second force conduction assembly applies acting force to the second beam elastic body, so that the second beam elastic body deforms and drives the third fiber bragg grating sensor and the fourth fiber bragg grating sensor to deform.
2. The fiber bragg grating fluid pressure measurement device of claim 1, wherein said first force-conducting assembly comprises a first wedge and a first hemisphere;
the first wedge body is arranged on the end face of the first isolation part, which is far away from the liquid containing cavity; the first hemispherical body is arranged on the end face of the first wedge body, which is far away from the first isolation component, and the arc-shaped surface of the first hemispherical body is adjacent to the end face of the first beam-type elastomer.
3. The fiber bragg grating liquid pressure measurement device of claim 2, wherein said first beam-like elastomer comprises a fixed end and a free end;
the fixed end is fixedly arranged on the shell, and the free end is adjacent to the arc-shaped surface of the first hemispherical body;
when the acting force exerted by the first hemispherical body is not received, the plane of the fixed end and the free end is perpendicular to the surface of the shell; the free end moves when subjected to the force exerted by the first hemisphere.
4. The fiber bragg grating liquid pressure measurement device of claim 3 wherein said first fiber bragg grating assembly further comprises a first stopper, a second stopper and a third stopper;
the first limiting block is arranged on one side, far away from the first force conduction component, of the first beam-type elastomer, and the first limiting block is used for limiting the moving distance of the free end of the first beam-type elastomer;
the second limiting block and the third limiting block are arranged in the liquid containing cavity, the second limiting block and the third limiting block are positioned on the same plane, and the plane where the second limiting block and the third limiting block are positioned is parallel to the end face of the first isolation part; the second limiting block and the third limiting block are used for limiting the first isolation component to move towards the liquid containing cavity.
5. The fiber bragg grating liquid pressure measurement device of claim 1, wherein a threaded damping hole is formed in the housing; the thread damping hole is used for injecting liquid to be detected into the liquid containing cavity.
6. The fiber bragg grating fluid pressure measurement device of claim 1, wherein the first fiber bragg grating assembly further comprises a first seal end cap;
the first seal end cap is disposed on a side of the first beam elastomer remote from the first force transmitting assembly.
7. A fiber bragg grating liquid pressure measurement method applied to the fiber bragg grating liquid pressure measurement device according to any one of claims 1 to 6, the method comprising:
acquiring the force load sensitivity on the first beam elastomer and the sectional area of the first isolation component;
after the liquid to be measured is contained in the liquid containing cavity, acquiring the total wavelength drift of the first fiber bragg grating sensor, the total wavelength drift of the second fiber bragg grating sensor, the total wavelength drift of the third fiber bragg grating sensor and the total wavelength drift of the fourth fiber bragg grating sensor;
calculating a first acting force according to the total wavelength drift of the first fiber bragg grating sensor, the total wavelength drift of the second fiber bragg grating sensor, the total wavelength drift of the third fiber bragg grating sensor, the total wavelength drift of the fourth fiber bragg grating sensor and the force load sensitivity on the first beam-type elastomer; the first acting force is acting force applied to the first beam-type elastic body under the pressure action of liquid to be detected in the liquid containing cavity;
calculating a liquid pressure value according to the first acting force and the sectional area of the first isolation component; the liquid pressure value is the pressure value of the liquid to be measured in the liquid containing cavity.
8. The method of claim 7, wherein the first force is calculated by the formula:
Δλ FBG2 -Δλ FBG1 +Δλ FBG3 -Δλ FBG4 ＝4k F21 F 21 ；
wherein Deltalambda FBG1 Representation ofTotal wavelength drift, Δλ, of the first fiber bragg grating sensor FBG2 Representing the total wavelength drift, deltalambda, of the second fiber grating sensor FBG3 Indicating the total wavelength drift of the third fiber bragg grating sensor, delta lambda FBG4 Representing the total wavelength drift, k, of the fourth fiber bragg grating sensor F21 Representing the sensitivity of force load on the first beam elastomer, F 21 Representing the first force.
9. The fiber bragg grating liquid pressure measurement method of claim 7, wherein the liquid pressure value is calculated by the formula:
P 2 ＝F 21 ×S MP1 ；
wherein F is 21 Representing the first force, P 2 Representing the liquid pressure value, S MP1 Representing the cross-sectional area of the first isolation assembly.
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