CN116973592A - Ocean current flow speed monitoring device based on vibration sensitive type optical fiber sensing - Google Patents
Ocean current flow speed monitoring device based on vibration sensitive type optical fiber sensing Download PDFInfo
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- CN116973592A CN116973592A CN202310943882.4A CN202310943882A CN116973592A CN 116973592 A CN116973592 A CN 116973592A CN 202310943882 A CN202310943882 A CN 202310943882A CN 116973592 A CN116973592 A CN 116973592A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/02—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring forces exerted by the fluid on solid bodies, e.g. anemometer
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
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Abstract
The invention discloses a ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing, which comprises a submarine cable, a distributed optical fiber vibration sensing system and n spindle-shaped structural bodies, wherein the submarine cable is connected with the ocean current flow velocity monitoring device through the optical fiber vibration sensing system; the n spindle-shaped structures are sequentially and fixedly nested outside the submarine cable, the distance L between two adjacent spindle-shaped structures meets the requirement of one or a plurality of spatial resolutions, the n spindle-shaped structures deform optical fibers in the submarine cable under the action of ocean currents, ocean current flow velocity information is converted into torque information of the submarine cable, and then the torque information is converted into phase change information of transmitted light in the submarine cable optical fibers; and the distributed optical fiber vibration sensing system calculates the current ocean current flow velocity of the ocean surface where the current ocean cable is positioned according to the phase change relation of the flow velocity and the transmitted light in the ocean cable optical fiber. The invention can collect the strain information of the submarine cable under water for a long time, the collected data has strong objectivity, and the sea current flow velocity of the depth of the submarine cable can be truly reflected.
Description
Technical Field
The invention belongs to the technical field of optical fiber sensing, and particularly relates to a device and a method for monitoring ocean current flow velocity based on vibration-sensitive optical fiber sensing.
Background
With the beginning of the 20 th century oceanography becoming an independent discipline, technological developments are continually pushing people to explore and develop the ocean. The ocean current flow rate is one of the most intuitive and important parameters of ocean state, and the real-time monitoring of the ocean current flow rate is a serious problem in ocean scientific research and industrial development.
On the one hand, knowing the current flow rate and direction can help the offshore vessel to plan an optimal route to avoid the sea area with a faster flow rate, and fuel and time costs are saved while the occurrence of offshore accidents is reduced. In addition, when maritime accidents occur to perform search and rescue actions, the drifting direction and speed of the personnel and articles lost or in danger at sea are closely related to the sea flow, and the search and rescue personnel can be helped to narrow the search and rescue range by knowing the flow speed and direction of the sea flow in advance, so that the search and rescue efficiency is improved. On the other hand, from the viewpoints of ocean resource utilization and environmental protection, the ocean current related information can help fishermen select the optimal fishing ground to improve capturing efficiency, and meanwhile, when ocean energy development is carried out, the optimal ocean energy equipment layout and design scheme can be helped to be selected. In addition, when marine pollution such as oil leakage occurs, prediction of the current flow rate and direction can help predict the spread range and speed of the pollutant, and take effective pollution control measures in time. For ocean science research, long-time monitoring of ocean current flow speed is helpful for understanding important problems such as substance migration rules in the ocean, substance circulation processes of an ocean ecological system, ocean climate change and ocean topography evolution, and provides important data support for ocean science research.
However, the existing methods for measuring the ocean current flow velocity have a plurality of fatal problems including rotor type flowmeters, laser Doppler flowmeters, ocean environment detection analysis radars and the like. If the traditional rotor flow velocity meter has the defects of high starting flow velocity, instability, large volume, inconvenient use and carrying and the like, the natural flow state of water flow can be destroyed during flow measurement, so that the measurement accuracy is affected. When aquatic weed floats exist in water, the rotating shaft is wound, and besides the serious influence on the flow velocity, the safety threat to the velocimeter is also existed. The laser Doppler velocimeter has the advantages that due to the fact that sea surface environments are complex and changeable, suspended particles in the air and suspended organisms in the sea water can influence a propagation path of laser, and measurement accuracy is difficult to guarantee. In addition, the laser doppler flowmeters have the problems of heavy equipment, high cost, need of skilled operators and the like. The marine environment detection analysis radar has high noise resistance due to serious electromagnetic signal interference on the sea surface. The distributed optical fiber sensing technology has the advantages of strong electromagnetic interference resistance, simple equipment, high sensitivity and the like, so that the distributed optical fiber sensing technology has important significance for monitoring the ocean current flow speed in real time. There is a need for a monitoring device that can effectively use the distributed optical fiber sensing technology for real-time monitoring of the ocean current velocity.
Disclosure of Invention
The technical problems to be solved are as follows: the invention provides a ocean current flow velocity monitoring device and method based on vibration sensitive optical fiber sensing, which can collect strain information of an ocean cable under water for a long time, the collected data has strong objectivity, the ocean current flow velocity of the depth of the ocean cable can be truly reflected, and the ocean current flow velocity monitoring device and method have an important guarantee function for real-time monitoring of the ocean current flow velocity for a long time.
The technical scheme is as follows:
the ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing comprises an ocean cable, a distributed optical fiber vibration sensing system and n spindle-shaped structural bodies, wherein n is an even number greater than or equal to 2;
the submarine cable is positioned at the sea level to be tested;
the n spindle-shaped structures are sequentially and fixedly nested outside the submarine cable, the distance L between two adjacent spindle-shaped structures meets the requirement of one or a plurality of spatial resolutions, the n spindle-shaped structures deform optical fibers in the submarine cable under the action of ocean currents, the ocean current flow velocity information is converted into torque information of the submarine cable, and then the torque information is converted into phase change information of transmitted light in the submarine cable optical fibers;
the distributed optical fiber vibration sensing system is connected with the upper end of the submarine cable, receives and processes and analyzes phase change information of transmitted light in the submarine cable optical fiber, and calculates and obtains the current sea current flow velocity of the sea level where the submarine cable is located according to the phase change relation of the flow velocity and the transmitted light in the submarine cable optical fiber.
Further, the spindle-shaped structure is made of polyolefin elastomer.
Further, the number of the spindle-shaped structures and the distance between the adjacent structures are related to the density of the sea cables and the material density of the spindle-shaped structures, and the equivalent density of the sea cables nested with the spindle-shaped structures approaches to the density of the sea level to be measured.
Further, the n spindle-shaped structures are arranged at equal intervals, two adjacent spindle-shaped structures are positioned at two sides of the submarine cable, and central symmetry axes of all the spindle-shaped structures are positioned in the same plane.
Further, the spindle-shaped structure includes a first transition portion and a second transition portion connected to each other, the first transition portion having a lateral width greater than a lateral width of the second transition portion; the first conversion part is provided with a hole, the submarine cable passes through the hole, and waterproof adhesive is filled between the submarine cable and the hole so that the spindle-shaped structure body is fixedly nested outside the submarine cable.
Further, a metal counterweight is placed in the first conversion part, so that the gravity center of the spindle-shaped structure body is located at the end part of the first conversion part far away from the second conversion part, and the central axis of the spindle-shaped structure body under the action of no ocean current is always perpendicular to the sea level.
Further, the extending areas of the parts of the spindle-shaped structures located on the two sides of the submarine cable are different.
Further, the extension areas of the parts of the spindle-shaped structures located on the two sides of the submarine cable are doubled.
Further, the submarine cable comprises an outer sheath, an armored steel wire, an inner sheath, a steel pipe and a strain measuring optical fiber;
the outer sheath is positioned at the outer side of the inner sheath, and gaps between concentric circles formed by the outer sheath and the inner sheath are uniformly filled with a plurality of armoured steel wires; the strain measuring optical fiber is sleeved in a steel pipe made of stainless steel, and the gap is filled with fiber paste; the filled steel tube is arranged in the inner sheath, and the gap is filled with filler and then stranded into a cable.
The invention also discloses a ocean current flow speed monitoring method based on vibration-sensitive optical fiber sensing, which is realized by adopting the ocean current flow speed monitoring device;
the ocean current flow velocity monitoring method comprises the following steps:
s1, measuring the sea water depth of a sea cable working position, and selecting the depth to be measured;
s2, calculating the number and arrangement spacing of the spindle-shaped structures needed to be nested on the submarine cable, so that the equivalent density of the submarine cable nested with the spindle-shaped structures approaches to the seawater density at the depth to be measured;
s3, connecting a distributed optical fiber vibration sensing system at the upper end of the submarine cable, wherein the optical fibers are connected by using a flange; placing the lower end of the submarine cable in seawater to enable the submarine cable to stably float at the depth to be measured;
and S4, demodulating data transmitted back by the strain measuring optical fiber in the submarine cable in real time, and acquiring the current sea current flow velocity at the current measuring depth according to the phase change relation of the flow velocity and the transmitted light in the submarine cable optical fiber.
The beneficial effects are that:
firstly, according to the ocean current flow velocity monitoring device based on vibration sensitive type optical fiber sensing, POE elastomer is adopted as the material of the spindle-shaped structure body nested on the ocean cable, and the POE elastomer has high elasticity, high-strength physical and mechanical properties, excellent ageing resistance and corrosion resistance, and has longer service life and maintenance period compared with the traditional flow velocity monitoring device under the long-time working environment of monitoring the ocean current flow velocity in real time.
Secondly, according to the ocean current flow velocity monitoring device based on vibration sensitive type optical fiber sensing, the density of the ocean cables is larger than that of the sea water, the density of the spindle-shaped structures is slightly smaller than that of the sea water, and the monitoring device can adjust the overall equivalent density by controlling the nesting number of the spindle-shaped structures and the spacing between the adjacent structures, so that the ocean current flow velocity of different water depths is measured, and the speed measuring range of the device is greatly improved.
Thirdly, according to the ocean current flow velocity monitoring device based on the vibration sensitive optical fiber sensing, spindle-shaped structures nested on the ocean cable are arranged at equal intervals left and right, and central symmetry axes of all the structures are positioned on the same plane, so that balance of weights at two sides of the ocean cable is ensured, and additional deformation of the ocean cable is avoided; in addition, the periodic structure strengthens acting force of ocean currents on the submarine cable, and is beneficial to demodulating optical phase change information transmitted in optical fibers in the submarine cable in the later period.
Fourth, compared with the existing ocean current flow speed detection mode, the ocean current flow speed monitoring device based on vibration-sensitive optical fiber sensing has the advantages that the optical fiber is used as a signal transmission medium, and the ocean current flow speed monitoring device has good electromagnetic interference resistance; the whole system only comprises two parts of submarine cable and signal demodulation processing equipment, and the device is simple and convenient to operate; in addition, after the submarine cable is successfully laid, the long-time real-time monitoring of the submarine current flow speed can be realized without the field operation of personnel.
Drawings
FIG. 1 is a schematic diagram of a vibration-sensitive fiber sensing-based ocean current flow velocity monitoring device according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view of a submarine cable used in an embodiment of the invention.
Fig. 3 is a schematic view of a spindle-shaped structure according to an embodiment of the present invention.
Detailed Description
The following examples will provide those skilled in the art with a more complete understanding of the invention, but are not intended to limit the invention in any way.
Example 1
Referring to fig. 1, the embodiment discloses a ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing, wherein the ocean current flow velocity monitoring device comprises an ocean cable, a distributed optical fiber vibration sensing system and n spindle-shaped structural bodies, wherein n is an even number greater than or equal to 2;
the submarine cable is positioned at the sea level to be tested;
the n spindle-shaped structures are sequentially and fixedly nested outside the submarine cable, so that the distance L between every two adjacent spindle-shaped structures meets one or a plurality of requirements on spatial resolution, the n spindle-shaped structures deform optical fibers in the submarine cable under the action of ocean currents, ocean current flow velocity information is converted into torque information of the submarine cable, and then the torque information is converted into phase change information of transmission light in the submarine cable optical fibers;
the distributed optical fiber vibration sensing system is connected with the upper end of the submarine cable, receives and processes and analyzes phase change information of transmitted light in the submarine cable optical fiber, and calculates and obtains the current sea current flow velocity of the sea level where the submarine cable is located according to the phase change relation of the flow velocity and the transmitted light in the submarine cable optical fiber.
For long-term ocean current flow rate monitoring, the signal demodulation processing module of the distributed optical fiber vibration sensing system can be arranged at a wharf, so that operation and maintenance of operation and maintenance personnel and real-time monitoring of the ocean current flow rate are facilitated.
Fig. 2 is a cross-sectional view of a submarine cable used in an embodiment of the invention. The submarine cable comprises an outer sheath, armored steel wires, an inner sheath, a steel pipe and a strain measuring optical fiber, wherein the outer sheath is positioned at the outer side of the inner sheath, a plurality of armored steel wires are uniformly filled in gaps between concentric circles formed by the outer sheath and the inner sheath, the strain measuring optical fiber is sleeved in the steel pipe made of stainless steel, and fiber paste is filled in the gaps; the filled steel tube is arranged in the inner sheath, and the gap is filled with filler and then stranded into a cable; in this embodiment, the submarine cable is used for protecting an optical fiber structure and for establishing a transmission link between an underwater signal and a marine demodulation device, the upper end is connected with the signal demodulation processing module, and the lower end is used for receiving the ocean current flow velocity information, so that the purpose of acquiring the sensing data under the sea at sea is achieved.
Fig. 3 is a schematic view of a spindle-shaped structure according to an embodiment of the present invention. The spindle-shaped structure comprisesThe first conversion part and the second conversion part are connected with each other, and the transverse width of the first conversion part is larger than that of the second conversion part; the first conversion part is provided with a hole, the submarine cable passes through the hole, and waterproof adhesive is filled between the submarine cable and the hole so that the spindle-shaped structure body is fixedly nested outside the submarine cable. As a preferable example, the spindle-shaped structure is made of POE material and has a density of 0.9g/cm 3 The material has high elasticity, high strength, physical and mechanical properties, and excellent ageing resistance and corrosion resistance under the premise of low density. Illustratively, the individual spindle-shaped structures weigh 400g with an internal counterweight, have an axial height of 40cm, a butt lateral length of 10cm, a center thickness of 6cm, and a bore for nesting located 4cm from the butt in the axial center. As the outer diameter of the submarine cable used in the system is 3cm, the size of the hole for nesting is slightly larger than 3cm and is 3.1-3.2 cm, and waterproof adhesive is used for firmness after nesting to the corresponding position, so that the submarine cable is tightly attached to the outside of the submarine cable, relative rotation between the submarine cable and the submarine cable is avoided, and the measurement accuracy of the system is reduced due to the reduction of the impact effect of the ocean current.
In order to obtain different pressures at two sides of the sea cable so as to achieve the purpose of converting the sea current flow velocity information into the torque information of the sea cable, the spindle-shaped structure body in the embodiment has larger difference of length and thickness at the two sides of the sea cable, so that the extension areas of the two sides are different, for example, the extension area S1 of the longer and thinner end is twice as large as the extension area S2 of the thicker and shorter end. Since the ocean pressure within 30cm of the axial height of the structure body can be regarded as equal pressure approximately, and S1 and S2 are located in the same plane and s1=2xs2, according to the pressure formula p=f/S, the pressure F1 applied to the extension surface of the longer and thinner end is twice the pressure F2 applied to the extension surface of the thicker and shorter end. Because of the pressure difference between the upper side and the lower side of the submarine cable, the submarine cable can twist at the positions of the nested spindle-shaped structures to generate certain torque, so that the optical fiber in the submarine cable is deformed, and the phase of transmitted light in the optical fiber is changed. When the ocean current flow velocity is changed, the pressure P is changed, and under the condition that the stressed areas at the two sides are unchanged, the pressure P and the stressed pressure F are in a linear relation, so that a certain linear mapping relation exists between the phase of the transmitted light of the ocean current flow velocity in the optical fiber, and the current ocean current flow velocity is obtained through demodulation processing of the phase signals.
As a preferable example, a metal counterweight is placed inside the spindle-shaped structure, and a hastelloy alloy resistant to acid corrosion can be used as the metal, so that unbalance of the mass of each structure due to long-term seawater infiltration corrosion is avoided. In addition, the metal counterweights are all placed at the same position of the thicker end of the structural body, so that the whole gravity center of the structural body is positioned at the port of the thicker end, the ocean current impact is always perpendicular to the extension surface of the spindle-shaped structural body in a calm state, the datum points of the ocean current impact are defined for measurement of different ocean current flow rates, and the measurement accuracy of the system is improved. As in the previous example, a metal counterweight with a weight of 150g is placed inside the spindle-shaped structure, and the metal counterweight is located at the port of the thick end, so that the central axis of the spindle-shaped structure under no ocean current interference is always perpendicular to the ocean surface, thereby ensuring that the ocean current impact is always perpendicular to the extension surface of the spindle-shaped structure in a calm state.
In the layout design of the spindle-shaped structures, the installation mode that the spindle-shaped structures are arranged on two sides of the submarine cable at equal intervals left and right and the central symmetry axes of all the structures are located in the same plane is adopted, so that balance of weights on two sides of the submarine cable is guaranteed, the submarine cable does not generate extra strain when the submarine cable is impacted by ocean currents, and the influence of bending deformation of the submarine cable on measurement accuracy is eliminated. In addition, the periodic structure strengthens acting force of ocean currents on the submarine cable, is beneficial to enhancing the phase change degree of transmitted light in optical fibers in the submarine cable, and is convenient for subsequent demodulation processing.
Example two
The embodiment of the invention provides a sea current flow rate monitoring method based on vibration-sensitive optical fiber sensing, which is realized based on the sea current flow rate monitoring system, and concretely comprises the following steps:
s1, measuring the sea water depth of a submarine cable working place and selecting the required depth to be measured. In this embodiment, the following steps are described by taking the ocean current flow velocity at the position where the needed measurement depth is 10m underwater in the sea area of south China as an example.
S2, calculating the number and arrangement spacing of the spindle-shaped structures needed to be nested on the submarine cable, so that the equivalent density of the submarine cable nested with the spindle-shaped structures approaches to the seawater density at the depth to be measured. The sea water density of 10m under the sea area of south China sea can be measured to be about 1.05g/cm3 in advance, if a sea cable with the length of 100m, the sectional area of 28.27cm2 and the mass of 4kg/m is selected, the overall equivalent density of POE material adopted by the spindle-shaped structure body and internal metal counterweight added by the spindle-shaped structure body is 0.87g/cm3, and the volume of the single structure body is about 2000cm 3 From the above information, it can be deduced that the equivalent density of the whole speed measuring device is 1.052g/cm when 90 spindle-shaped structures are nested 3 . Therefore, the 90 spindle-shaped structural bodies are only required to be arranged at intervals of 1.1m and nested on the submarine cable, and the speed measuring device can be stably positioned at the depth of 10m under water.
S3, the upper end of the submarine cable is connected with a distributed optical fiber vibration sensing system, wherein the optical fibers are connected by using a flange; the lower end is placed in the sea water, and the sea water is waited to float at the depth to be measured until the sea water is stable. For example, the distributed optical fiber vibration sensing system can adopt a phi-OTDR system, the wavelength of the used laser is 1550nm, the pulse width is 30ns, the pumping current is 450mA, and the spatial resolution is 1m.
And S4, demodulating data transmitted back by the strain measuring optical fiber in the submarine cable in real time, and acquiring the current sea current flow velocity at the current measuring depth according to the phase change relation of the flow velocity and the transmitted light in the submarine cable optical fiber.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the invention without departing from the principles thereof are intended to be within the scope of the invention as set forth in the following claims.
Claims (10)
1. The ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing is characterized in that the ocean current flow velocity monitoring system comprises an ocean cable, a distributed optical fiber vibration sensing system and n spindle-shaped structural bodies, wherein n is an even number greater than or equal to 2;
the submarine cable is positioned at the sea level to be tested;
the n spindle-shaped structures are sequentially and fixedly nested outside the submarine cable, the distance L between two adjacent spindle-shaped structures meets the requirement of one or a plurality of spatial resolutions, the n spindle-shaped structures deform optical fibers in the submarine cable under the action of ocean currents, the ocean current flow velocity information is converted into torque information of the submarine cable, and then the torque information is converted into phase change information of transmitted light in the submarine cable optical fibers;
the distributed optical fiber vibration sensing system is connected with the upper end of the submarine cable, receives and processes and analyzes phase change information of transmitted light in the submarine cable optical fiber, and calculates and obtains the current sea current flow velocity of the sea level where the submarine cable is located according to the phase change relation of the flow velocity and the transmitted light in the submarine cable optical fiber.
2. The device for monitoring the ocean current flow velocity based on vibration-sensitive optical fiber sensing according to claim 1, wherein the spindle-shaped structure is made of polyolefin elastomer.
3. The ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing according to claim 1, wherein the number of spindle-shaped structures and the distance between adjacent structures are related to the density of ocean cables and the material density of the spindle-shaped structures, and the equivalent density of the ocean cables nested with the spindle-shaped structures approaches to the density of the ocean surface to be measured.
4. The ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing according to claim 1, wherein the n spindle-shaped structures are arranged at equal intervals, two adjacent spindle-shaped structures are positioned at two sides of the ocean cable, and central symmetry axes of all spindle-shaped structures are positioned in the same plane.
5. The vibration-sensitive optical fiber sensing-based ocean current flow velocity monitoring device of claim 1, wherein the spindle-shaped structure includes a first transition portion and a second transition portion connected to each other, the first transition portion having a lateral width greater than a lateral width of the second transition portion; the first conversion part is provided with a hole, the submarine cable passes through the hole, and waterproof adhesive is filled between the submarine cable and the hole so that the spindle-shaped structure body is fixedly nested outside the submarine cable.
6. The ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing according to claim 5, wherein a metal counterweight is placed inside the first conversion portion, so that the center of gravity of the spindle-shaped structure is located at the end portion of the first conversion portion away from the second conversion portion, and the center axis of the spindle-shaped structure under no ocean current is always perpendicular to the ocean surface.
7. The ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing according to claim 1, wherein the extending areas of the portions of the spindle-shaped structure located on both sides of the ocean cable are different.
8. The vibration-sensitive optical fiber sensing-based ocean current flow velocity monitoring device according to claim 7, wherein the extending areas of the spindle-shaped structures at both sides of the ocean cable differ by one time.
9. The ocean current flow velocity monitoring device based on vibration-sensitive optical fiber sensing according to claim 1, wherein the ocean cable comprises an outer sheath, an armored steel wire, an inner sheath, a steel tube and a strain-measuring optical fiber;
the outer sheath is positioned at the outer side of the inner sheath, and gaps between concentric circles formed by the outer sheath and the inner sheath are uniformly filled with a plurality of armoured steel wires; the strain measuring optical fiber is sleeved in a steel pipe made of stainless steel, and the gap is filled with fiber paste; the filled steel tube is arranged in the inner sheath, and the gap is filled with filler and then stranded into a cable.
10. A method for monitoring the current flow rate based on vibration-sensitive optical fiber sensing, which is characterized in that the method for monitoring the current flow rate is realized by adopting the current flow rate monitoring device according to any one of claims 1 to 9;
the ocean current flow velocity monitoring method comprises the following steps:
s1, measuring the sea water depth of a sea cable working position, and selecting the depth to be measured;
s2, calculating the number and arrangement spacing of the spindle-shaped structures needed to be nested on the submarine cable, so that the equivalent density of the submarine cable nested with the spindle-shaped structures approaches to the seawater density at the depth to be measured;
s3, connecting a distributed optical fiber vibration sensing system at the upper end of the submarine cable, wherein the optical fibers are connected by using a flange; placing the lower end of the submarine cable in seawater to enable the submarine cable to stably float at the depth to be measured;
and S4, demodulating data transmitted back by the strain measuring optical fiber in the submarine cable in real time, and acquiring the current sea current flow velocity at the current measuring depth according to the phase change relation of the flow velocity and the transmitted light in the submarine cable optical fiber.
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