CN113358269A - Pore water fiber bragg grating differential pressure sensor and pressure detection device - Google Patents
Pore water fiber bragg grating differential pressure sensor and pressure detection device Download PDFInfo
- Publication number
- CN113358269A CN113358269A CN202110660256.5A CN202110660256A CN113358269A CN 113358269 A CN113358269 A CN 113358269A CN 202110660256 A CN202110660256 A CN 202110660256A CN 113358269 A CN113358269 A CN 113358269A
- Authority
- CN
- China
- Prior art keywords
- fiber
- spring
- pore water
- pressure sensor
- shell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
- G01L19/0627—Protection against aggressive medium in general
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/14—Housings
- G01L19/142—Multiple part housings
- G01L19/143—Two part housings
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The invention relates to a pore water fiber grating differential pressure sensor and a pressure detection device, and belongs to the technical field of sensors. The pore water fiber grating differential pressure sensor comprises a pressure diaphragm, a shell, a first spring, a second spring and a fiber grating; the shell comprises an upper shell and a lower shell, the interior of the shell is hollow so as to form a hydraulic chamber, and the hydraulic chamber is divided into an upper hydraulic chamber and a lower hydraulic chamber by a pressure diaphragm; the first spring is arranged in the upper hydraulic chamber, the upper end of the first spring is fixedly connected to the upper shell, and the lower end of the first spring is fixedly connected to the center of the upper surface of the pressure diaphragm; the second spring is arranged in the lower hydraulic chamber, the upper end of the second spring is fixedly connected to the center of the lower surface of the pressure diaphragm, and the lower end of the second spring is fixedly connected to the lower shell; the upper end and the lower end of the fiber grating are respectively and fixedly connected with the upper end and the lower end of the first spring. The pore water fiber grating differential pressure sensor has high static pressure capability, high sensitivity and high measurement precision, and can meet the accurate measurement requirement of the seabed pore water superporous pressure value.
Description
Technical Field
The invention belongs to the technical field of sensors, and particularly relates to a pore water fiber bragg grating differential pressure sensor and a pressure detection device.
Background
The deep sea bottom engineering geology in-situ observation is an important component in transparent sea, and especially has an important function for analyzing the deep sea dynamic geology process when being used for long-term observation on the deep sea geology.
In the current stage of deep sea bottom engineering geology in-situ observation, pore hydrostatic pressure is mainly measured by adopting a pore pressure sensor, however, sea water pressure change influences the sea bottom pore water pressure, and the dynamic characteristic of sea bottom sediments can be truly reflected by the super pore pressure instead of static pore pressure, so that the observation of the sea bottom super pore pressure is realized, and the research on the sea bottom dynamic geological process is greatly facilitated.
At present, a pore pressure sensor is mainly adopted for detecting the seabed pore water pressure, the traditional pore pressure sensor comprises an electronic pore pressure sensor and a fiber bragg grating pore pressure sensor, however, the pore water pressure detected by the pore pressure sensor and the pore pressure detected by the fiber bragg grating pore pressure sensor are both hydrostatic pressure existing in the seabed, and the seabed excess pore pressure value and the change thereof are difficult to accurately observe. Want through the hydrostatic pressure of traditional pore pressure sensor measurement, it is difficult to realize to accurately decompose out super pore pressure on hydrostatic pressure basis, need master more information such as this sea area internal wave, morning and evening tides, and the analytical process is loaded down with trivial details and is difficult to guarantee the accuracy of data, in addition, current pore pressure sensor exists defect such as precision is not high, sensitivity is not enough, is difficult to distinguish the information of super pore pressure value more.
The fiber grating differential pressure sensor can also measure the pressure difference, and is mainly applied to the industries of petrochemical industry, automobile industry, electric power energy and the like at present, however, the fiber grating differential pressure sensor needs to accurately measure the deep sea pore water super pore pressure, and the fiber grating differential pressure sensor is required to reach a static pressure range larger than 20Mpa, a pressure difference range +/-0.5 Mpa and a precision grade +/-0.1% FS, but the fiber grating differential pressure sensor applied in domestic commerce generally has the problems of low static pressure measurement capability and insufficient precision grade, and cannot meet the accurate measurement requirement of the seabed pore water super pore pressure value.
Disclosure of Invention
Aiming at the defects in the existing submarine pore water pressure measurement, the invention provides a pore water fiber grating differential pressure sensor and a pressure detection device.
The invention provides a pore water fiber grating differential pressure sensor, comprising:
the pressure diaphragm is horizontally arranged;
the shell comprises an upper shell and a lower shell which are respectively arranged above and below the pressure diaphragm, and the upper shell and the lower shell are tightly connected so that the pressure diaphragm is clamped between the upper shell and the lower shell; the shell is hollow so as to form a hydraulic chamber, the hydraulic chamber is divided into an upper hydraulic chamber positioned in the upper shell and a lower hydraulic chamber positioned in the lower shell by a pressure diaphragm, and the upper hydraulic chamber and the lower hydraulic chamber are isolated from each other; the upper shell is provided with an upper liquid inlet for communicating the upper hydraulic chamber with the outside of the upper shell, and the lower shell is provided with a lower liquid inlet for communicating the lower hydraulic chamber with the outside of the lower shell;
the first spring is arranged in the upper hydraulic chamber and stretches along the vertical direction, the upper end of the first spring is fixedly connected to the upper shell, and the lower end of the first spring is fixedly connected to the center of the upper surface of the pressure diaphragm;
the second spring is arranged in the lower hydraulic chamber and stretches along the vertical direction, the upper end of the second spring is fixedly connected to the center of the lower surface of the pressure diaphragm, and the lower end of the second spring is fixedly connected to the lower shell;
the fiber bragg grating is arranged in the upper hydraulic chamber in the vertical direction and penetrates through the first spring, the upper end and the lower end of the fiber bragg grating are respectively provided with an upper reserved fiber section and a lower reserved fiber section, the upper reserved fiber section and the lower reserved fiber section are respectively and fixedly connected to the upper end and the lower end of the first spring, and the upper end of the upper reserved fiber section penetrates out of the upper hydraulic chamber to form a tail fiber;
the central axis of the first spring, the central axis of the second spring and the center of the pressure diaphragm are arranged in a collinear manner.
The technical scheme adopts a sensitive structure consisting of the spring, the pressure diaphragm and the spring, so that the sensitivity and the measurement precision of the sensor are improved, meanwhile, the spring structures are arranged on the two sides of the pressure diaphragm, so that the fiber bragg grating can be prevented from being broken and damaged under the condition of overlarge pressure difference, the static pressure range of the sensor is favorably improved, and the accurate measurement requirement of the seabed pore water excess pore pressure value can be met.
In some embodiments, the first spring comprises a first spring body sleeved outside the fiber grating, and a first upper connecting shaft and a first lower connecting shaft which are respectively connected to the upper end and the lower end of the first spring body, the first upper connecting shaft and the first lower connecting shaft are coaxially arranged, the upper end of the first upper connecting shaft is fixedly connected to the upper shell, the lower end of the first lower connecting shaft is fixedly connected to the pressure diaphragm, and the upper reserved fiber section and the lower reserved fiber section of the fiber grating are respectively fixedly connected to the first upper connecting shaft and the first lower connecting shaft; the second spring comprises a second spring body, a second upper connecting shaft and a second lower connecting shaft which are connected to the upper end and the lower end of the second spring body respectively, the second spring body, the second upper connecting shaft and the second lower connecting shaft are arranged coaxially, the upper end of the second upper connecting shaft is fixedly connected to the pressure diaphragm, and the lower end of the second lower connecting shaft is fixedly connected to the lower shell.
In some embodiments, the upper hydraulic chamber comprises a first hydraulic section located at the lower part and a first limit guide section located at the upper part, the first hydraulic section is in contact with the pressure diaphragm, the first limit guide section is far away from the pressure diaphragm, the first spring body is located in the first limit guide section, and the inner diameter of the first limit guide section is matched with the outer diameter of the first spring body; the lower hydraulic chamber comprises a second hydraulic section located on the upper portion and a second limiting guide section located on the lower portion, the second hydraulic section is in contact with the pressure diaphragm, the second limiting guide section is far away from the pressure diaphragm, the second spring body is located in the second limiting guide section, and the inner diameter of the second limiting guide section is matched with the outer diameter of the second spring body. This technical scheme restricts the flexible direction of first spring body and second spring body and prevents the bending respectively through the first spacing direction section of setting and the spacing direction section of second, is favorable to ensureing measurement accuracy.
In some embodiments, the hydraulic chamber penetrates through the shell along the vertical direction, and an upper through opening and a lower through opening are respectively formed at the top of the upper shell and the bottom of the lower shell; an upper stop block for shielding the upper through hole is arranged at the upper through hole, a through hole for the upper reserved optical fiber section of the optical fiber grating to penetrate through is formed in the middle of the upper stop block, and the upper end of the first spring is fixedly connected to the upper stop block; a lower stop block for shielding the lower through hole is arranged at the lower through hole, and the lower end of the second spring is fixedly connected to the lower stop block. This technical scheme is convenient for process the hydraulic pressure room in the casing, is convenient for install pressure diaphragm, fiber grating, first spring and second spring simultaneously.
In some embodiments, the housing further includes a top cap covering the top of the upper housing, the top cap is tightly connected to the upper housing, and the upper reserved fiber section of the fiber grating passes through the top cap.
Besides, the invention also provides a pore water pressure detection device, which comprises:
the probe rod extends along the vertical direction, a tube cavity extending along the vertical direction is arranged in the probe rod, the tube cavity is divided into an upper tube cavity and a lower tube cavity from top to bottom, and the probe rod is provided with an upper water inlet communicated with the upper tube cavity and a lower water inlet communicated with the lower tube cavity;
in the pore water fiber grating differential pressure sensor, the pore water fiber grating differential pressure sensor is arranged between the upper pipe cavity and the lower pipe cavity of the probe rod and isolates the upper pipe cavity from the lower pipe cavity, an upper liquid inlet of the pore water fiber grating differential pressure sensor is communicated with the upper pipe cavity, and a lower liquid inlet of the pore water fiber grating differential pressure sensor is communicated with the lower pipe cavity;
and the fiber grating demodulation system is used for signal detection, data processing and storage of the pore water fiber grating differential pressure sensor and is connected with a tail fiber of the pore water fiber grating differential pressure sensor.
According to the technical scheme, the high-sensitivity and high-precision pore water fiber bragg grating differential pressure sensor is adopted, so that the accurate measurement of the seabed pore water overpressure value can be realized.
In some embodiments, the pore water pressure detection device further comprises a sealed cabin, and the sealed cabin is arranged at the top of the probe rod; the fiber bragg grating demodulation system is packaged in the sealed cabin and is connected with a tail fiber of the pore water fiber bragg grating differential pressure sensor through a cabin penetrating connecting piece. The technical scheme can realize long-term data acquisition and observation of the pressure of the pore water in the seabed.
In some embodiments, the fiber grating demodulation system comprises a broadband light source, a fiber isolator and a fiber circulator which are sequentially connected through a first transmission fiber, a spectrum demodulation module connected to the fiber circulator through a second transmission fiber, and a main controller electrically connected to the spectrum demodulation module; the optical fiber circulator is connected with a tail fiber of the pore water optical fiber grating differential pressure sensor.
In some embodiments, the pore water pressure detection device further comprises a sensor mounting seat arranged between the upper tube cavity and the lower tube cavity, and the sensor mounting seat is annular; the upper shell of the pore water fiber grating differential pressure sensor is positioned in the upper pipe cavity, the pore water fiber grating differential pressure sensor penetrates through the annular hole of the sensor mounting seat so that the lower shell of the pore water fiber grating differential pressure sensor extends into the lower pipe cavity, and a sealing element used for sealing a gap between the fiber grating differential pressure sensor and the sensor mounting seat is arranged between the pore water fiber grating differential pressure sensor and the sensor mounting seat so that the upper pipe cavity and the lower pipe cavity are isolated from each other.
In some embodiments, the lower liquid inlet of the pore water fiber grating differential pressure sensor is arranged at the bottom of the lower shell, a step surface for abutting against the sensor mounting seat is processed at the bottom of the lower shell around the lower liquid inlet, and the sealing element is arranged on the step surface.
Based on the technical scheme, the pore water fiber bragg grating differential pressure sensor and the pressure detection device in the embodiment of the invention have high static pressure capability, high sensitivity and high measurement precision, and can meet the accurate measurement requirement of the seabed pore water superporous pressure value.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
fig. 1 is a schematic structural diagram of a pore water fiber grating differential pressure sensor according to an embodiment of the present invention;
FIG. 2 is an enlarged view of a portion of FIG. 1 at A;
fig. 3 is a schematic structural diagram of a pore water pressure detection device according to an embodiment of the present invention;
fig. 4 is a block diagram of a fiber bragg grating demodulation system and a pore water fiber bragg grating differential pressure sensor in the pore water pressure detection apparatus according to the embodiment of the present invention.
In the figure:
1. a pore water fiber grating differential pressure sensor; 11. a pressure diaphragm; 12. a housing; 121. a top cap; 122. an upper housing; 123. a lower housing; 124. an upper hydraulic chamber; 1241. a first hydraulic section; 1242. a first limit guide section; 125. a lower hydraulic chamber; 1251. a second hydraulic section; 1252. a second limit guide section; 126. an upper liquid inlet; 127. a liquid inlet and outlet; 128. an upper stop block; 129. a lower stop block; 13. a first spring; 131. a first spring body; 132. a first upper connecting shaft; 133. a first lower connecting shaft; 14. a second spring; 141. a second spring body; 142. a second upper connecting shaft; 143. a second lower connecting shaft; 15. a fiber grating; 151. an optical fiber section is reserved; 152. a lower reserved optical fiber section; 16. tail fiber; 17. a protective sleeve; 18. a protective cap; 19. a seal member;
2. a probe rod; 21. a lumen; 211. an upper lumen; 212. a lower lumen; 22. an upper water inlet; 23. a lower water inlet; 3. sealing the cabin; 4. a cabin penetration connecting piece; 5. a sensor mount; 6. a fiber grating demodulation system; 61. a broadband light source; 62. a fiber isolator; 63. a fiber optic circulator; 64. a spectrum demodulation module; 65. and a master controller.
Detailed Description
The technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in fig. 1, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
As shown in fig. 1 and fig. 2, in an exemplary embodiment of the pore water fiber grating differential pressure sensor 1 of the present invention, the pore water fiber grating differential pressure sensor 1 includes a pressure diaphragm 11, a housing 12, a first spring 13, a second spring 14, and a fiber grating 15. Wherein, the pressure diaphragm 11 is arranged horizontally; the housing 12 includes an upper housing 122 and a lower housing 123 respectively disposed above and below the pressure diaphragm 11, the upper housing 122 and the lower housing 123 being tightly coupled such that the pressure diaphragm 11 is sandwiched between the upper housing 122 and the lower housing 123; the housing 12 is hollow inside to form a hydraulic chamber, the hydraulic chamber is divided by the pressure diaphragm 11 into an upper hydraulic chamber 124 located in the upper housing 122 and a lower hydraulic chamber 125 located in the lower housing 123, and the upper hydraulic chamber 124 and the lower hydraulic chamber 125 are isolated from each other; the upper shell 122 is provided with an upper liquid inlet 126 for communicating the upper hydraulic chamber 124 with the outside of the upper shell 122, and the lower shell 123 is provided with a lower liquid inlet 127 for communicating the lower hydraulic chamber 125 with the outside of the lower shell 123; the first spring 13 is arranged in the upper hydraulic chamber 124 and stretches along the vertical direction, the upper end of the first spring is fixedly connected to the upper shell 122, and the lower end of the first spring is fixedly connected to the center of the upper surface of the pressure diaphragm 11; the second spring 14 is disposed in the lower hydraulic chamber 125 and extends and contracts in the vertical direction, and has an upper end fixedly connected to the center of the lower surface of the pressure diaphragm 11 and a lower end fixedly connected to the lower housing 123; the center axis of the first spring 13, the center axis of the second spring 14, and the center of the pressure diaphragm 11 are arranged in a collinear manner. The fiber bragg grating 15 is disposed in the upper hydraulic chamber 124 in the vertical direction and penetrates through the first spring 13, the upper end and the lower end of the fiber bragg grating are respectively provided with an upper reserved fiber section 151 and a lower reserved fiber section 152, the upper reserved fiber section 151 and the lower reserved fiber section 152 are respectively fixedly connected to the upper end and the lower end of the first spring 13, and the upper end of the upper reserved fiber section 151 penetrates through the upper hydraulic chamber 124 to form the tail fiber 16.
The working principle of the pore water fiber grating differential pressure sensor 1 is as follows: seawater is introduced into an upper hydraulic chamber 124 through an upper liquid inlet 126, seabed pore water is introduced into a lower hydraulic chamber 125 through a lower liquid inlet 127, pressure difference occurs on two sides of a pressure membrane 11 due to pressure difference between the seawater and the pore water, the pressure membrane 11 deforms to drive a first spring 13 to stretch or compress, and the upper end and the lower end of an optical fiber grating 15 are fixedly connected to the upper end and the lower end of the first spring 13 through an upper reserved optical fiber section 151 and a lower reserved optical fiber section 152 respectively, so that the optical fiber grating 15 is stressed and strained due to stretching or compressing of the first spring 13, the central wavelength of the optical fiber grating 15 is shifted, and the magnitude of the pressure difference can be determined according to the central wavelength shift.
In the above exemplary embodiment, the fiber grating 15 is fixed on the first spring 13, and the first spring 13, the pressure diaphragm 11 and the second spring 14 constitute the sensitive structure of the pore water fiber grating differential pressure sensor 1, when there is a pressure difference across the pressure diaphragm 11, the stress of the pressure diaphragm 11 and the first spring 13 changes, thereby causing the strain of the fiber bragg grating 15, and the sensitive structure formed by the spring, the pressure diaphragm and the spring can effectively improve the sensitivity and the measurement precision of the sensor, meanwhile, the spring structures are arranged on the two sides of the pressure diaphragm 11, so that the fiber bragg grating 15 can be prevented from being broken and damaged under the condition of overlarge pressure difference, the static pressure range of the sensor can be improved, the static pressure range is more than 20Mpa, the measurement precision grade under the static pressure of more than 20Mpa can reach +/-0.1% FS, and the accurate measurement requirement of the sea floor pore water excess pore pressure value can be met. In addition, by changing the size and the thickness of the pressure diaphragm 11 and the parameter design of the first spring 13 and the second spring 14, the measurement precision of the sensor can be adjusted, and different measurement precision requirements can be met, so that the measurement requirements of different depths of the seabed and geological conditions can be met.
In some embodiments, as shown in fig. 2, the first spring 13 includes a first spring body 131 sleeved outside the fiber bragg grating 15, and a first upper connecting shaft 132 and a first lower connecting shaft 133 respectively connected to the upper end and the lower end of the first spring body 131, the first upper connecting shaft 132, and the first lower connecting shaft 133 are coaxially disposed, the upper end of the first upper connecting shaft 132 is fixedly connected to the upper housing 122, the lower end of the first lower connecting shaft 133 is fixedly connected to the pressure diaphragm 11, and the upper reserved fiber segment 151 and the lower reserved fiber segment 152 of the fiber bragg grating 15 are respectively fixedly connected to the first upper connecting shaft 132 and the first lower connecting shaft 133; as shown in fig. 1, the second spring 14 includes a second spring body 141, and a second upper connecting shaft 142 and a second lower connecting shaft 143 connected to the upper end and the lower end of the second spring body 141, respectively, the second spring body 141, the second upper connecting shaft 142, and the second lower connecting shaft 143 are coaxially disposed, the upper end of the second upper connecting shaft 142 is fixedly connected to the pressure diaphragm 11, and the lower end of the second lower connecting shaft 143 is fixedly connected to the lower housing 123. The arrangement of the first spring 13 and the second spring 14 can ensure the stability and the consistency of elastic deformation of the springs in the process of tension. In this embodiment, the upper reserved optical fiber segment 151 and the lower reserved optical fiber segment 152 of the fiber grating 15 are respectively bonded to the first upper connecting shaft 132 and the first lower connecting shaft 133 of the first spring 13 by glass cement. The lower end of the first lower connecting shaft 133 of the first spring 13 is preferably connected to the pressure diaphragm 11 by spot welding, and the upper end of the second upper connecting shaft 142 of the second spring 14 is preferably connected to the pressure diaphragm 11 by spot welding.
In some embodiments, when the stiffness of the first spring 13 and the second spring 14 is low, in order to avoid the influence of the bending of the first spring 13 and the second spring 14 when the first spring 13 and the second spring 14 are extended and contracted on the measurement accuracy and the sensitivity of the sensor, it is preferable that: as shown in fig. 1, the upper hydraulic chamber 124 includes a first hydraulic section 1241 located at a lower portion and a first limit guide section 1242 located at an upper portion, the first hydraulic section 1241 is in contact with the pressure diaphragm 11 to directly apply pressure to the pressure diaphragm 11, the first limit guide section 1242 is away from the pressure diaphragm 11, the first spring body 131 is located in the first limit guide section 1242, an inner diameter of the first limit guide section 1242 is matched with an outer diameter of the first spring body 131 to limit the first spring body 131 from being expanded and contracted only in a vertical direction and prevent the first spring body 131 from being bent when being expanded and contracted; the lower hydraulic chamber 125 includes a second hydraulic section 1251 at an upper portion and a second limit guide section 1252 at a lower portion, the second hydraulic section 1251 is in contact with the pressure diaphragm 11 to directly pressurize the pressure diaphragm 11, the second limit guide section 1252 is away from the pressure diaphragm 11, the second spring body 141 is located in the second limit guide section 1252, an inner diameter of the second limit guide section 1252 is matched with an outer diameter of the second spring body 141 to restrict the second spring body 141 from being contracted only in a vertical direction and prevent the second spring body 141 from being bent when being contracted.
In some embodiments, in order to facilitate the processing of the hydraulic chamber in the housing 12 and to facilitate the installation of the pressure diaphragm 11, the fiber grating 15, the first spring 13, and the second spring 14, as shown in fig. 1, the hydraulic chamber penetrates the housing 12 in the vertical direction, and forms an upper through-hole and a lower through-hole at the top of the upper housing 122 and the bottom of the lower housing 123, respectively; an upper stop block 128 for shielding the upper through hole is arranged at the upper through hole, a through hole for the upper reserved optical fiber section 151 of the optical fiber grating 15 to penetrate out is arranged in the middle of the upper stop block 128, and the upper end of the first spring 13 is fixedly connected to the upper stop block 128; a lower stop block 129 for shielding the lower through hole is arranged at the lower through hole, and the lower end of the second spring 14 is fixedly connected to the lower stop block 129. When the fiber grating pressure sensor is installed, a first spring 13 and a second spring 14 are connected to the pressure diaphragm 11 according to the principle of center alignment, and the fiber grating 15 is fixed on the first spring 13; the pressure diaphragm 11 is clamped between the upper shell 122 and the lower shell 123 through the tight connection between the upper shell 122 and the lower shell 123, and the first spring 13 penetrates into the upper hydraulic chamber 124 and the second spring 14 penetrates into the lower hydraulic chamber 125; the upper reserved optical fiber section 151 of the fiber bragg grating 15 penetrates out of the through hole of the upper stop block 128, the upper end of the first spring 13 is pulled out through the upper through hole and connected to the upper stop block 128, and then the upper stop block 128 is arranged at the upper through hole; the lower end of the second spring 14 is drawn out through the lower through-hole and connected to the lower stopper 129, and the lower stopper 129 is mounted at the lower through-hole. It should be noted that the connection mode between the upper casing 122 and the lower casing 123 is preferably a threaded connection; in order to ensure that the pressure diaphragm 11 is firmly connected between the upper shell 122 and the lower shell 123, the pressure diaphragm 11 may be welded to the upper shell 122 or the lower shell 123; the first spring 13 and the upper stop 128 are preferably connected by welding, and the second spring 14 and the lower stop 129 are preferably connected by welding; the upper stop 128 is preferably welded at the upper through opening and the lower stop 129 is preferably welded at the lower through opening.
In some embodiments, to ensure the tight connection of the pigtail to the housing, as shown in fig. 1, the housing 12 further includes a top cap 121 covering the top of the upper housing 122, the top cap 121 is tightly connected to the upper housing 122, and the upper reserved fiber segment 151 of the fiber grating 15 passes through the top cap 121. It should be noted that the connection between the top cap 121 and the upper case 122 is preferably a threaded connection.
In addition, in order to prolong the service life of the sensor, the housing 12 (including the top cap 121, the upper housing 122 and the lower housing 123) is preferably made of stainless steel, which is advantageous for application in a severe marine environment. The pigtail 16 is sheathed with a protective sheath 17 and a protective cap 18 to prevent it from being pulled apart.
Based on the above-mentioned pore water fiber bragg grating differential pressure sensor 1, as shown in fig. 3 and 4, an embodiment of the present invention further provides a pore water pressure detection device, which includes a probe rod 2, the above-mentioned pore water fiber bragg grating differential pressure sensor 1, and a fiber bragg grating demodulation system 6. The probe rod 2 extends along the vertical direction, a tube cavity 21 extending along the vertical direction is arranged in the probe rod 2, the tube cavity 21 is divided into an upper tube cavity 211 and a lower tube cavity 212 from top to bottom, and the probe rod 2 is provided with an upper water inlet 22 communicated with the upper tube cavity 211 and a lower water inlet 23 communicated with the lower tube cavity 212; the pore water fiber bragg grating differential pressure sensor 1 is arranged between an upper pipe cavity 211 and a lower pipe cavity 212 of the probe rod 2 and isolates the upper pipe cavity 211 from the lower pipe cavity 212, an upper liquid inlet 126 of the pore water fiber bragg grating differential pressure sensor 1 is communicated with the upper pipe cavity 211, and a lower liquid inlet 127 of the pore water fiber bragg grating differential pressure sensor 1 is communicated with the lower pipe cavity 212; the fiber grating demodulation system 6 is used for signal detection, data processing and storage of the pore water fiber grating differential pressure sensor 1, and the fiber grating demodulation system 6 is connected with a tail fiber 16 of the pore water fiber grating differential pressure sensor 1.
The application method of the pore water pressure detection device comprises the following steps: the lower end of the probe rod 2 is pressed into the sea bottom along the vertical direction, the lower water inlet 23 is positioned in the sea bottom, the upper water inlet 22 is positioned above the sea bottom, so that the sea bottom pore water enters the lower pipe cavity 212 through the lower water inlet 23, further enters the lower hydraulic chamber 125 through the lower liquid inlet 127 of the pore water fiber grating differential pressure sensor 1, simultaneously sea water enters the upper pipe cavity 211 through the upper water inlet 22, further enters the upper hydraulic chamber 124 through the upper liquid inlet 126 of the pore water fiber grating differential pressure sensor 1, the pressure diaphragm 11 is deformed due to the pressure difference on the two sides, the first spring 13 is driven to stretch or compress, the fiber grating 15 is stressed and strained, the central wavelength of the fiber grating 15 is changed, and the differential pressure information is demodulated by the fiber grating demodulating system 6 and stored.
The pore water pressure detection device adopts the high-sensitivity and high-precision pore water fiber bragg grating differential pressure sensor 1, and can realize accurate measurement of the seabed pore water overpressure value.
In some embodiments, for long-term data acquisition and observation of the seabed pore water pressure, as shown in fig. 3, the pore water pressure detection device further comprises a sealed cabin 3, wherein the sealed cabin 3 is arranged at the top of the probe rod 2; the fiber bragg grating demodulation system 6 is packaged in the sealed cabin 3 and is connected with a tail fiber 16 of the pore water fiber bragg grating differential pressure sensor 1 through the cabin penetrating connecting piece 4.
In some embodiments, as shown in fig. 4, the fiber grating demodulation system 6 includes a broadband light source 61, a fiber isolator 62 and a fiber circulator 63 connected in sequence by a first transmission fiber, a spectrum demodulation module 64 connected to the fiber circulator 63 by a second transmission fiber, and a master controller 65 electrically connected to the spectrum demodulation module 64; the fiber circulator 63 is connected with the tail fiber 16 of the pore water fiber grating differential pressure sensor 1. When the device is used, a broadband light source 61 emits an optical signal, the optical signal reaches the pore water fiber grating pressure difference sensor 1 through the optical fiber isolator 62 and the optical fiber circulator 63, the optical signal carrying pressure difference information is transmitted to the spectrum demodulation module 64 through the optical fiber circulator 63, the spectrum demodulation module 64 demodulates the optical signal into an electric signal and transmits the electric signal to the main controller 65, and the main controller 65 processes and stores data. It should be noted that the fiber grating demodulation system 6 necessarily further includes a power supply for supplying power to the broadband light source 61, the spectrum demodulation module 64 and the main controller 65, so as to ensure that the system works normally. It will be appreciated that other fibre grating demodulation systems 6 may be used by those skilled in the art, for example a fibre grating demodulator in cooperation with a master controller.
In some embodiments, in order to facilitate the installation of the above-mentioned pore water fiber bragg grating differential pressure sensor 1 between the upper tube cavity 211 and the lower tube cavity 212 of the probe rod 2, as shown in fig. 3, the pore water pressure detection apparatus further includes a sensor mount 5 disposed between the upper tube cavity 211 and the lower tube cavity 212, and the sensor mount 5 is annular; the upper shell 122 of the pore water fiber grating differential pressure sensor 1 is located in the upper pipe cavity 211, the pore water fiber grating differential pressure sensor 1 penetrates through the annular hole of the sensor mounting seat 5 so that the lower shell 123 of the pore water fiber grating differential pressure sensor 1 extends into the lower pipe cavity 212, and a sealing element 19 for sealing a gap between the fiber grating differential pressure sensor 1 and the sensor mounting seat 5 is arranged between the pore water fiber grating differential pressure sensor 1 and the sensor mounting seat 5 so that the upper pipe cavity 211 and the lower pipe cavity 212 are isolated from each other.
Specifically, as shown in fig. 1, the lower liquid inlet 127 of the pore water fiber grating differential pressure sensor 1 is opened at the bottom of the lower housing 123 (specifically, opened on the lower stopper 129), a step surface for abutting against the sensor mounting seat 5 is processed around the lower liquid inlet 127 at the bottom of the lower housing 123, and the sealing member 19 is disposed on the step surface. The seal 19 is preferably a gasket.
The relationship between the wavelength drift and the strain of the fiber grating is explained as follows:
when the optical fiber is subjected to a tension in the vertical direction (z direction), the strain in each direction can be obtained according to the principle of material mechanics:
in formula (1): e is the elastic modulus of the optical fiber; iota is the Poisson ratio of the optical fiber; epsilonxIs the x-direction strain; epsilonyIs the y-direction strain; epsilonzIs the z-direction strain; and p is the applied pressure.
Central wavelength lambda of optical fiber gratingBExpressed as:
λB＝2neffΛ (2)
in formula (2): n iseffIs the effective refractive index of the fiber grating; and Λ is the fiber grating period.
According to the formula (2) and the photoelastic effect, the following results are obtained:
in formula (3): delta lambdaBThe variation of the central wavelength of the fiber grating; lambda [ alpha ]BIs the central wavelength of the fiber grating; epsilonzIs the z-direction strain; n iseffIs the effective refractive index of the fiber grating; iota is the Poisson ratio of the optical fiber; p is a radical of11、p12Is the elasto-optic coefficient.
The relationship between the wavelength drift and the strain of the fiber grating is as follows:
in formula (4):
through the description of the embodiments of the pore water fiber bragg grating differential pressure sensor and the pressure detection device, it can be seen that the embodiments of the pore water fiber bragg grating differential pressure sensor and the pressure detection device at least have one or more of the following advantages:
1. the sensitivity and the measurement precision of the sensor are improved by adopting a sensitive structure consisting of the spring, the pressure diaphragm and the spring, and meanwhile, the spring structures are arranged on the two sides of the pressure diaphragm, so that the fiber bragg grating can be prevented from being broken and damaged under the condition of overlarge pressure difference, the static pressure range of the sensor is favorably improved, and the accurate measurement requirement of the pressure value of the seabed pore water exceeding the pore can be met;
2. the measurement precision of the sensor can be adjusted by changing the size and the thickness of the pressure diaphragm and the parameter design of the first spring and the second spring, and different measurement precision requirements are met, so that the measurement requirements of different depths and geological conditions of the seabed are met;
3. the sensor has the advantages of simple structure, easily obtained materials, low cost and high sensitivity.
Finally, it should be noted that: the embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.
Claims (10)
1. Pore water fiber bragg grating differential pressure sensor, its characterized in that includes:
the pressure diaphragm is horizontally arranged;
the shell comprises an upper shell and a lower shell which are respectively arranged above and below the pressure diaphragm, and the upper shell and the lower shell are tightly connected so that the pressure diaphragm is clamped between the upper shell and the lower shell; the shell is hollow to form a hydraulic chamber, the hydraulic chamber is divided into an upper hydraulic chamber positioned in the upper shell and a lower hydraulic chamber positioned in the lower shell by the pressure diaphragm, and the upper hydraulic chamber and the lower hydraulic chamber are isolated from each other; the upper shell is provided with an upper liquid inlet for communicating the upper hydraulic chamber with the outside of the upper shell, and the lower shell is provided with a lower liquid inlet for communicating the lower hydraulic chamber with the outside of the lower shell;
the first spring is arranged in the upper hydraulic chamber and stretches along the vertical direction, the upper end of the first spring is fixedly connected to the upper shell, and the lower end of the first spring is fixedly connected to the center of the upper surface of the pressure diaphragm;
the second spring is arranged in the lower hydraulic chamber and stretches along the vertical direction, the upper end of the second spring is fixedly connected to the center of the lower surface of the pressure diaphragm, and the lower end of the second spring is fixedly connected to the lower shell;
the fiber bragg grating is arranged in the upper hydraulic chamber in the vertical direction and penetrates through the first spring, the upper end and the lower end of the fiber bragg grating are respectively provided with an upper reserved fiber section and a lower reserved fiber section, the upper reserved fiber section and the lower reserved fiber section are respectively and fixedly connected to the upper end and the lower end of the first spring, and the upper end of the upper reserved fiber section penetrates through the upper hydraulic chamber to form a tail fiber;
the central axis of the first spring, the central axis of the second spring and the center of the pressure diaphragm are arranged in a collinear manner.
2. The pore water fiber bragg grating differential pressure sensor according to claim 1, wherein the first spring comprises a first spring body sleeved outside the fiber bragg grating, and a first upper connecting shaft and a first lower connecting shaft which are respectively connected to the upper end and the lower end of the first spring body, the first upper connecting shaft and the first lower connecting shaft are coaxially arranged, the upper end of the first upper connecting shaft is fixedly connected to the upper shell, the lower end of the first lower connecting shaft is fixedly connected to the pressure diaphragm, and an upper reserved fiber section and a lower reserved fiber section of the fiber bragg grating are respectively fixedly connected to the first upper connecting shaft and the first lower connecting shaft; the second spring comprises a second spring body, and a second upper connecting shaft and a second lower connecting shaft which are respectively connected to the upper end and the lower end of the second spring body, the second upper connecting shaft and the second lower connecting shaft are coaxially arranged, the upper end of the second upper connecting shaft is fixedly connected to the pressure diaphragm, and the lower end of the second lower connecting shaft is fixedly connected to the lower shell.
3. The pore water fiber bragg grating differential pressure sensor according to claim 2, wherein the upper hydraulic chamber comprises a first hydraulic section at a lower part and a first limit guide section at an upper part, the first hydraulic section is in contact with the pressure diaphragm, the first limit guide section is far away from the pressure diaphragm, the first spring body is positioned in the first limit guide section, and the inner diameter of the first limit guide section is matched with the outer diameter of the first spring body; the lower hydraulic chamber comprises a second hydraulic section positioned on the upper portion and a second limiting guide section positioned on the lower portion, the second hydraulic section is in contact with the pressure diaphragm, the second limiting guide section is far away from the pressure diaphragm, the second spring body is positioned in the second limiting guide section, and the inner diameter of the second limiting guide section is matched with the outer diameter of the second spring body.
4. The pore water fiber bragg grating differential pressure sensor according to claim 1 or 3, wherein the hydraulic chamber penetrates through the housing in a vertical direction, and an upper through port and a lower through port are formed at the top of the upper housing and the bottom of the lower housing, respectively; an upper stop block for shielding the upper through hole is arranged at the upper through hole, a through hole for the penetration of an upper reserved optical fiber section of the optical fiber grating is formed in the middle of the upper stop block, and the upper end of the first spring is fixedly connected to the upper stop block; and a lower stop block for shielding the lower through hole is arranged at the lower through hole, and the lower end of the second spring is fixedly connected to the lower stop block.
5. The pore water fiber bragg grating differential pressure sensor according to claim 4, wherein the housing further comprises a top cap covering the top of the upper housing, the top cap is tightly connected with the upper housing, and the upper reserved fiber section of the fiber bragg grating passes through the top cap.
6. Pore water pressure detection device, its characterized in that includes:
the probe rod extends along the vertical direction, a tube cavity extending along the vertical direction is arranged in the probe rod, the tube cavity is divided into an upper tube cavity and a lower tube cavity from top to bottom, and the probe rod is provided with an upper water inlet communicated with the upper tube cavity and a lower water inlet communicated with the lower tube cavity;
the pore water fiber grating differential pressure sensor according to any one of claims 1 to 5, wherein the pore water fiber grating differential pressure sensor is installed between and separates an upper pipe cavity and a lower pipe cavity of the probe rod, an upper liquid inlet of the pore water fiber grating differential pressure sensor is communicated with the upper pipe cavity, and a lower liquid inlet of the pore water fiber grating differential pressure sensor is communicated with the lower pipe cavity;
and the fiber grating demodulation system is used for signal detection, data processing and storage of the pore water fiber grating differential pressure sensor, and is connected with a tail fiber of the pore water fiber grating differential pressure sensor.
7. The pore water pressure detection device according to claim 6, further comprising a sealed cabin disposed on top of the probe; the fiber bragg grating demodulation system is packaged in the sealed cabin and is connected with the tail fiber of the pore water fiber bragg grating differential pressure sensor through a cabin penetrating connecting piece.
8. The pore water pressure detection device according to claim 6 or 7, wherein the fiber grating demodulation system comprises a broadband light source, a fiber isolator and a fiber circulator which are sequentially connected through a first transmission fiber, a spectrum demodulation module connected to the fiber circulator through a second transmission fiber, and a main controller electrically connected to the spectrum demodulation module; and the optical fiber circulator is connected with a tail fiber of the pore water optical fiber grating differential pressure sensor.
9. The pore water pressure detecting device according to claim 6, further comprising a sensor mount disposed between the upper tube cavity and the lower tube cavity, the sensor mount being annular; the upper shell of the pore water fiber grating differential pressure sensor is positioned in the upper pipe cavity, the pore water fiber grating differential pressure sensor penetrates through the annular hole of the sensor mounting seat so that the lower shell of the pore water fiber grating differential pressure sensor extends into the lower pipe cavity, and a sealing element used for sealing a gap between the fiber grating differential pressure sensor and the sensor mounting seat is arranged between the pore water fiber grating differential pressure sensor and the sensor mounting seat so as to enable the upper pipe cavity and the lower pipe cavity to be isolated from each other.
10. The pore water pressure detecting device according to claim 9, wherein the lower inlet of the pore water fiber grating differential pressure sensor is opened at the bottom of the lower housing, a step surface for abutting against the sensor mounting seat is processed at the bottom of the lower housing around the lower inlet, and the sealing member is arranged on the step surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110660256.5A CN113358269B (en) | 2021-06-15 | 2021-06-15 | Pore water fiber bragg grating differential pressure sensor and pressure detection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110660256.5A CN113358269B (en) | 2021-06-15 | 2021-06-15 | Pore water fiber bragg grating differential pressure sensor and pressure detection device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113358269A true CN113358269A (en) | 2021-09-07 |
| CN113358269B CN113358269B (en) | 2022-03-01 |
Family
ID=77534460
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110660256.5A Active CN113358269B (en) | 2021-06-15 | 2021-06-15 | Pore water fiber bragg grating differential pressure sensor and pressure detection device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113358269B (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6304686B1 (en) * | 2000-02-09 | 2001-10-16 | Schlumberger Technology Corporation | Methods and apparatus for measuring differential pressure with fiber optic sensor systems |
| US6422084B1 (en) * | 1998-12-04 | 2002-07-23 | Weatherford/Lamb, Inc. | Bragg grating pressure sensor |
| US20090151423A1 (en) * | 2007-12-18 | 2009-06-18 | Xu Wu | Pressure measuring device and method |
| CN204346620U (en) * | 2015-01-21 | 2015-05-20 | 西安科技大学 | A kind of rock pressure [in mine sensor based on fiber grating |
| CN104819802A (en) * | 2015-05-06 | 2015-08-05 | 中国海洋大学 | Deep-sea floor excess pore water pressure measurement feeler lever range protection device |
| CN210464755U (en) * | 2019-08-20 | 2020-05-05 | 青岛海洋科学与技术国家实验室发展中心 | Optical fiber pressure sensor |
-
2021
- 2021-06-15 CN CN202110660256.5A patent/CN113358269B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6422084B1 (en) * | 1998-12-04 | 2002-07-23 | Weatherford/Lamb, Inc. | Bragg grating pressure sensor |
| US6304686B1 (en) * | 2000-02-09 | 2001-10-16 | Schlumberger Technology Corporation | Methods and apparatus for measuring differential pressure with fiber optic sensor systems |
| US20090151423A1 (en) * | 2007-12-18 | 2009-06-18 | Xu Wu | Pressure measuring device and method |
| CN204346620U (en) * | 2015-01-21 | 2015-05-20 | 西安科技大学 | A kind of rock pressure [in mine sensor based on fiber grating |
| CN104819802A (en) * | 2015-05-06 | 2015-08-05 | 中国海洋大学 | Deep-sea floor excess pore water pressure measurement feeler lever range protection device |
| CN210464755U (en) * | 2019-08-20 | 2020-05-05 | 青岛海洋科学与技术国家实验室发展中心 | Optical fiber pressure sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113358269B (en) | 2022-03-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2830281C (en) | Multi-point pressure sensor and uses thereof | |
| JP6510522B2 (en) | Sensor for detecting pressure waves in liquid | |
| US20200181864A1 (en) | Effective stress cell for direct measurement of effective stress in saturated soil | |
| NO330841B1 (en) | Fiber optic hydrophone | |
| CN101625273B (en) | Fiber bragg grating osmometer | |
| CN1743821A (en) | High-performance optical fiber pressure sensor | |
| CN111750796A (en) | Bragg fiber grating static and dynamic automatic compensation type structural deformation monitoring system | |
| CN110702280A (en) | High-sensitivity fiber grating pressure sensor based on square diaphragm | |
| CN101832808A (en) | Taper chirped fiber grating liquid level sensor based on reflection spectrum bandwidth detection | |
| CN112097968A (en) | Optical fiber pressure and acceleration sensor and installation and calibration method thereof | |
| CN113358269B (en) | Pore water fiber bragg grating differential pressure sensor and pressure detection device | |
| WO2016205269A1 (en) | Fiber optic pressure apparatus, methods, and applications | |
| CN113447411B (en) | System and method for measuring concentration of silt in water body by using optical fiber sensor | |
| CN109186825B (en) | Optical fiber macrobend pressure sensor and measuring system thereof | |
| CN205607584U (en) | Fiber grating air pressure sensor | |
| CN112432695B (en) | Spiral optical fiber distributed sound field direction judgment method based on elastic body | |
| CN113188691A (en) | Optical fiber Fabry-Perot sealed cavity pressure sensor and preparation method thereof | |
| CN210464755U (en) | Optical fiber pressure sensor | |
| CN111220262A (en) | Wavelength-adjustable acceleration sensor based on fiber laser | |
| CN110470426A (en) | A kind of fiber-optic grating sensor and measurement method that can measure temperature and pressure simultaneously | |
| CN201903415U (en) | Six-dimension force sensing device | |
| CN105509957B (en) | A kind of fiber bragg grating pressure sensor | |
| CN211143037U (en) | Static parameter sounding probe | |
| CN2506990Y (en) | Optical fiber raster water level sensor | |
| CN113514187A (en) | Epoxy diaphragm integrated fiber bragg grating pressure sensor and performance evaluation device thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |