A multifunctional optical fiber sensor, flow field monitoring system and method

Abstract

The present invention proposes a multifunctional optical fiber sensor, a flow field monitoring system and method, wherein the multifunctional optical fiber sensor comprises: an optical fiber, a waveguide trunk, a plurality of waveguide branches arranged in parallel, and a sensing component, wherein the waveguide trunk is formed in the optical fiber, the waveguide branch is formed in the optical fiber and is connected to the waveguide trunk, and the sensing component is connected to the waveguide branch, and the sensing component is at least used to generate a plurality of light source detection signals for detecting the temperature, pressure, and flow velocity of the flow field. The present invention enables the multifunctional optical fiber sensor to generate a plurality of light source detection signals for detecting the flow field, and to monitor a plurality of parameters of the flow field, integrating a plurality of monitoring functions into one, and the technical solution of the present invention is conducive to realizing the decoupling of temperature, pressure, and flow velocity signals by setting a plurality of waveguide branches, thereby improving the measurement accuracy of the multifunctional optical fiber sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of flow field sensors, and in particular to a multifunctional optical fiber sensor, a flow field monitoring system and a method. Background Art

[0002] As the "neuron" of flow field monitoring, the fiber optic flow field sensor can keenly sense parameters such as temperature, pressure, and flow velocity in the flow field. The fiber optic flow field sensor is usually used in the fields of ultra-high-speed aircraft flight status monitoring, nuclear reactor coolant monitoring, high-temperature smelting monitoring, etc. It has very important application value in the field of science and technology. However, the flow field sensor used in the existing technology has a single measurement parameter and does not meet the requirements of multi-parameter monitoring in high-temperature environments. The sapphire fiber-peroxidation cavity sensor can measure temperature and pressure at the same time. However, the existing sapphire fiber-peroxidation cavity sensor is not only large in size and complex in structure, but also cannot achieve the decoupling of temperature and pressure signals, resulting in inaccurate measurement results. Therefore, it is urgent to propose a new technology that can monitor multiple parameters, decouple signals, and measure accurately. Summary of the invention

[0003] An object of the present invention is to provide a multifunctional optical fiber sensor, a flow field monitoring system and a method, which are intended to solve the technical problems in the prior art that the flow field sensor has a single measurement parameter, cannot decouple signals, and has inaccurate measurements.

[0004] To achieve the above-mentioned purpose, the first aspect of an embodiment of the present application proposes a multifunctional optical fiber sensor, which includes: an optical fiber, a waveguide trunk, a plurality of waveguide branches arranged in parallel, and a sensing component, wherein the waveguide trunk is formed in the optical fiber, the waveguide branches are formed in the optical fiber and are connected to the waveguide trunk, the sensing component is connected to the waveguide branches, and the sensing component is at least used to generate a plurality of light source detection signals for detecting the temperature, pressure, and flow velocity of the flow field.

[0005] In a specific implementation of the first aspect of the present application, the sensing component includes a first sensing unit, the waveguide branch includes a first branch, the first sensing unit is connected to the first branch, the first sensing unit is used to generate a first detection signal for measuring an external temperature change ΔT, the first branch extends in a direction gradually approaching the first side of the optical fiber, and the first sensing unit includes a fiber Bragg grating.

[0006] In a specific implementation of the first aspect of the present application, the sensor assembly includes a second sensor unit, the waveguide branch includes a second branch, the second sensor unit is connected to the second branch, and the second sensor unit is used to generate a measurement of the external dynamic pressure change ΔP E And a second detection signal of the external fluid flow velocity u.

[0007] In a specific implementation of the first aspect of the present application, the second branch extends along the direction of the waveguide trunk, the second sensing unit includes a first microcavity and a diaphragm, the first microcavity is connected to the second branch, and the diaphragm is connected to the first microcavity to form a closed microcavity.

[0008] In a specific implementation of the first aspect of the present application, the sensor assembly includes a third sensor unit, the waveguide branch includes a third branch, the third sensor unit is connected to the third branch, and the third sensor unit is used to generate a measurement of the external static pressure change ΔP I The third detection signal.

[0009] In a specific implementation of the first aspect of the present application, the third branch extends in a direction gradually away from the first side portion of the optical fiber, and the third sensing unit includes a second microcavity, and an opening is provided on a side of the second microcavity away from the first side portion of the optical fiber.

[0010] In a specific implementation of the first aspect of the present application, the optical fiber includes any one of sapphire optical fiber, zirconium oxide optical fiber, and lutetium oxide optical fiber.

[0011] The second aspect of an embodiment of the present application proposes a flow field monitoring system, which includes a fiber optic sensor, a laser, a fiber optic circulator, and a signal processing module. The fiber optic sensor is the fiber optic sensor described in any one of the above embodiments. The fiber optic circulator includes three ports, and the three ports are respectively connected to the laser, the signal processing module, and the fiber optic sensor. The fiber optic circulator is at least used to receive and transmit the light source signal generated by the laser.

[0012] In a specific implementation of the second aspect of the present application, the fiber optic circulator receives multiple light source detection signals generated by the fiber optic sensor and transmits the multiple light source detection signals to the signal processing module. The signal processing module includes a photoelectric detector, a signal collector, and a computer device. The photoelectric detector is used to convert the multiple light source detection signals into digital electrical signals. The signal collector is used to collect the digital electrical signals and transmit them to the computer device. The computer device is used to filter the digital electrical signals and calculate the drift of the light source signal, the external temperature change ΔT, and the external static pressure change ΔP I , External dynamic pressure change ΔP E and flow rate u.

[0013] A third aspect of the embodiments of the present application provides a flow field monitoring method, using the flow field monitoring system described in any one of the above embodiments, the flow field monitoring method comprising:

[0014] The light source signal is emitted to the optical fiber circulator by a laser, and is transmitted to the multifunctional optical fiber sensor through the optical fiber circulator;

[0015] receiving a plurality of light source detection signals from the optical fiber sensor through the optical fiber circulator, transmitting the light source detection signals to the photoelectric detector, and converting the light source detection signals into digital electrical signals through the photoelectric detector;

[0016] Collecting the digital electrical signal through a signal collector and transmitting the digital signal to a computer device;

[0017] The digital electrical signal is filtered by the computer device, and the external temperature change ΔT and the external static pressure change ΔP are determined by calculating the drift of the light source signal. I , External dynamic pressure change ΔP E and flow rate u.

[0018] In a specific implementation of the third aspect of the present application, the drift of the light source signal is calculated to determine the ambient temperature change ΔT and the ambient static pressure change ΔP. I , External dynamic pressure change ΔP E And the flow rate u includes:

[0019] Monitor the reflection spectrum formed by the first sensing unit to determine the reflection spectrum drift Δλ of the fiber Bragg grating 1 , and according to the reflection spectrum drift amount Δλ 1 Determine the temperature change ΔT of the external environment;

[0020] Monitor the first resonance spectrum formed by the third sensing unit to determine the drift Δλ of the first resonance spectrum of the open microcavity 3 , and according to the temperature change ΔT and the first resonance spectrum drift Δλ 3 Determine the external static pressure change ΔP I ;

[0021] Monitor the second resonance spectrum formed by the second sensing unit to determine the drift Δλ of the second resonance spectrum of the closed microcavity 2 , and according to the temperature change ΔT, the external static pressure change ΔP I And the second resonance spectrum shift Δλ 2 , determine the external dynamic pressure change ΔP E ;

[0022] According to the external dynamic pressure change ΔP E Determine the flow velocity u of the external fluid.

[0023] Compared with the prior art, the multifunctional optical fiber sensor provided by the embodiment of the present invention has the following beneficial effects: the present invention enables the multifunctional optical fiber sensor to monitor multiple parameters of the flow field by setting a plurality of waveguide branches, and enables the multifunctional optical fiber sensor to generate a plurality of light source detection signals for detecting the flow field by setting a sensing component, thereby integrating a plurality of monitoring functions into one. The technical solution of the present invention simplifies the structure of the multifunctional optical fiber sensor, thereby simplifying the volume of the multifunctional optical fiber sensor. The technical solution of the present invention facilitates the decoupling of temperature and pressure signals by setting a plurality of waveguide branches, thereby improving the measurement accuracy of the multifunctional optical fiber sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0025] Figure 1 is a schematic diagram of the composition of a multifunctional optical fiber sensor provided by an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of another multifunctional optical fiber sensor provided by an embodiment of the present invention;

[0027] Figure 3 is a schematic structural diagram of a multifunctional optical fiber sensor provided by an embodiment of the present invention;

[0028] Figure 4 is a schematic diagram of a flow field monitoring system provided by an embodiment of the present invention;

[0029] Figure 5 is a schematic diagram of another flow field monitoring system provided by an embodiment of the present invention;

[0030] Figure 6 is a flowchart of a signal processing module provided by an embodiment of the present invention;

[0031] Figure 7 is a flow chart of a flow field monitoring method provided by an embodiment of the present invention;

[0032] Figure 8 yes Figure 7 The detailed flow chart of step S40 is shown.

[0033] Explanation of the accompanying drawings: waveguide trunk 10; first branch 11; second branch 12; third branch 13; first sensing unit 21; fiber Bragg grating 21a; second sensing unit 22; first microcavity 22a; diaphragm 22b; third sensing unit 23; second microcavity 23a; first side portion 30 of optical fiber; optical fiber sensor 100; optical fiber circulator 200; laser 300; signal processing module 400; photodetector 410; signal collector 420; computer equipment 430. DETAILED DESCRIPTION

[0034] In order to make the invention purpose, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described below are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0035] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0036] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0037] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting" depending on the context. Similarly, the phrase "if it is determined" or "if [the described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [the described condition or event] is detected" or "in response to detecting [the described condition or event]" depending on the context. In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0040] The first aspect of the embodiment of the present application provides a multifunctional optical fiber sensor 100. For details, please refer to Figure 1 and Figure 3 , Figure 1 is a schematic diagram of the composition of a multifunctional optical fiber sensor 100 provided in an embodiment of the present invention, Figure 3 It is a structural schematic diagram of a multifunctional optical fiber sensor 100 provided in an embodiment of the present invention. The multifunctional optical fiber sensor 100 shown includes: an optical fiber, a waveguide trunk 10, a plurality of waveguide branches arranged in parallel, and a sensor component. The waveguide trunk 10 is formed in the optical fiber, the waveguide branch is formed in the optical fiber and is connected to the waveguide trunk 10, the sensor component is connected to the waveguide branch, and the sensor component is at least used to generate a plurality of light source detection signals for detecting the temperature, pressure, and flow velocity of the flow field.

[0041] Compared with the prior art, the multifunctional optical fiber sensor 100 provided in the embodiment of the present invention has the following beneficial effects: the present invention enables the multifunctional optical fiber sensor 100 to monitor multiple parameters of the flow field by setting a plurality of waveguide branches, and enables the multifunctional optical fiber sensor 100 to generate a plurality of light source detection signals for detecting the flow field by setting a sensing component, thereby integrating a plurality of monitoring functions into one, and the technical solution of the present invention simplifies the structure of the multifunctional optical fiber sensor 100 so that the volume of the multifunctional optical fiber sensor 100 is simplified, and the technical solution of the present invention facilitates the decoupling of temperature and pressure signals by setting a plurality of waveguide branches, thereby improving the measurement accuracy of the multifunctional optical fiber sensor 100.

[0042] Please refer again Figure 3 In a specific implementation of the first aspect of the present application, the sensing component includes a first sensing unit 21, the waveguide branch includes a first branch 11, the first sensing unit 21 is connected to the first branch 11, the first branch 11 extends in a direction gradually approaching the first side portion 30 of the optical fiber, and the first sensing unit 21 includes a fiber Bragg grating 21a;

[0043] The first sensing unit 21 is used to generate a first detection signal for measuring the change in external temperature ΔT. The fiber Bragg grating 21a in the first sensing unit 21 generates a reflection spectrum that drifts with the change in the external measured temperature. The calculation formula is as follows: Δλ 1 =A 1 *ΔT, the reflection spectrum drift of the fiber Bragg grating 21a is only related to the temperature, so the temperature value of the measured environment can be obtained by monitoring the reflection spectrum drift of the fiber Bragg grating 21a, Δλ 1 A is the reflection spectrum drift of the fiber Bragg grating 21a; 1 is the temperature coefficient of the fiber Bragg grating 21a, which can be obtained by a prior temperature calibration experiment; ΔT is the change in the ambient temperature, which can be obtained by formula 1: Δλ 1 =A 1 * Calculate ΔT.

[0044] The grating period of the fiber Bragg grating 21a is 1-10um, and the grating period refers to the distance between two adjacent refractive index modulation units. The specific grating period can be selected from any value of 2um, 5um, 8um, 10um, and 2n*Λ=λ, where Λ is the grating period and λ is the wavelength. Further, the overall length of the fiber Bragg grating 21a can be set to 1-10mm, such as 1mm, 2mm, 4mm, 6mm, 8mm, 10mm, and the specific grating period Λ can be customized according to the central wavelength. Optionally, the first sensing unit 21 includes a spiral grating, and a detection signal for measuring the ambient temperature can be obtained through the spiral grating.

[0045] In a specific implementation of the first aspect of the present application, the sensor assembly includes a third sensor unit 23, the waveguide branch includes a third branch 13, the third sensor unit 23 is connected to the third branch 13, and the third sensor unit 23 is used to generate a measurement of the external static pressure change ΔP I The third detection signal. The third branch 13 extends in a direction gradually away from the first side portion 30 of the optical fiber, and the third sensing unit 23 includes a second microcavity 23a, and the second microcavity 23a is provided with an opening on a side away from the first side portion 30 of the optical fiber to form an open microcavity. The open microcavity is formed by femtosecond laser micromachining. The open microcavity of the third sensing unit 23 along the two end faces of the optical fiber axis will form an FPI interferometer structure, and its resonant spectrum will drift with the changes in the external temperature and static pressure. The specific calculation method is as shown in Formula 2: Δλ 3 =A 3 ΔT+B 3 ΔP I Among them, Δλ3 is the resonance spectrum drift of the open microcavity; A 3 is the temperature coefficient of the resonance spectrum drift of the open microcavity, B 3 is the temperature coefficient of the resonance spectrum drift of the open microcavity, which can be obtained by the previous temperature and pressure calibration experiment; ΔT is the change of the external ambient temperature, which can be calculated by formula 1. Therefore, the change of the external static pressure ΔP can be calculated by formula 2. I .

[0046] See also Figure 2 , Figure 2 1 is a schematic diagram of another multifunctional optical fiber sensor 100 provided in an embodiment of the present invention. In a specific implementation of the first aspect of the present application, the sensing component includes a second sensing unit 22, the waveguide branch includes a second branch 12, the second sensing unit 22 is connected to the second branch 12, and the second sensing unit 22 is used to generate a measurement of the external dynamic pressure change ΔP E and a second detection signal of the external fluid flow velocity u. The second branch 12 extends along the direction of the waveguide trunk 10. In this embodiment, the waveguide trunk 10 is arranged along the axial direction of the optical fiber from the middle of the first end of the optical fiber. One end of the first branch 11, one end of the second branch 12 and one end of the third branch 13 converge at the end of the waveguide trunk 10. The other end of the second branch 12 extends toward the second end of the optical fiber. The first branch 11 and the third branch 13 are arranged on both sides of the second branch 12. The other end of the first branch 11 is close to one side of the optical fiber, i.e., the first side portion 30 of the optical fiber. The other end of the third branch 13 is close to the other side opposite to the optical fiber. The first branch 11 and the third branch 13 can be arranged symmetrically relative to the central axis of the optical fiber. The second sensing unit 22 is located at the center of the second end of the optical fiber. The first sensing unit 23 and the third sensing unit 23 are arranged on both sides of the optical fiber and close to the second end of the optical fiber, so that the structure of the optical fiber sensor 100 is more compact. The second sensing unit 22 includes a first microcavity 22a and a diaphragm 22b. The first microcavity 22a is connected to the second branch 12. The first microcavity 22a is located at the end of the optical fiber. The diaphragm 22b is connected to the first microcavity 22a to form a closed microcavity. The first microcavity 22a is provided with an opening at the second end of the optical fiber, and the diaphragm 22b is sealed at the opening to form a closed microcavity. Specifically, the first microcavity 22a is connected to the second branch 12 by CO. 2 The closed microcavity is formed by sealing a diaphragm 22b at the end opening of the first microcavity 22a by laser welding wafers. The diaphragm 22b is a single crystal sapphire wafer, and the lateral spacing of the first microcavity 22a is 10um to 100um, such as 10um, 20um, 40um, 50um, 70um, 90um, etc.

[0047] The first microcavity 22a of the second sensing unit 22 and the bottom surface of the membrane 22b form a Fabry-Perot interferometer FPI structure, whose resonance spectrum will drift with the changes of external temperature, static pressure and dynamic pressure. The specific calculation method is as shown in Formula 3: Δλ 2 =A 2 ΔT+B 2 ΔP I +C 2 ΔP E Among them, Δλ 2 is the resonance spectrum drift of the closed microcavity; A 2 , B 2 and C 2 are the temperature, static pressure and dynamic pressure coefficients of the resonance spectrum drift of the closed microcavity, which can be obtained by prior calibration experiments; ΔT is the change in the external environment temperature, which can be calculated by formula 1, and the change in the external static pressure ΔP I It can be calculated by formula 2. Therefore, substituting it into formula 3 can calculate the change of external dynamic pressure ΔP E The flow velocity u can be calculated according to the following formula:

[0048]

[0049] Where ρ is the density of the external fluid.

[0050] The optical fiber is made of high temperature resistant material, and the waveguide trunk 10 and the plurality of parallel waveguide branches are engraved by laser processing, such as femtosecond laser engraving. The optical fiber includes any one of sapphire optical fiber, zirconium oxide optical fiber and lutetium oxide optical fiber. The single crystal optical fiber is a sapphire optical fiber with a maximum temperature resistance of more than 1800°C, the zirconium oxide optical fiber is an optical fiber with a maximum temperature resistance of more than 2200°C, and the lutetium oxide optical fiber is an optical fiber with a maximum temperature resistance of more than 2400°C.

[0051] Please refer to Figure 4 , Figure 4It is a schematic diagram of a flow field monitoring system provided in an embodiment of the present invention. The second aspect of the embodiment of the present application proposes a flow field monitoring system, the flow field monitoring system includes a fiber optic sensor 100, a laser 300, a fiber optic circulator 200, and a signal processing module 400. The fiber optic sensor 100 is the fiber optic sensor 100 described in any one of the above embodiments. The fiber optic circulator 200 includes three ports, and the three ports are respectively connected to the laser 300, the signal processing module 400, and the fiber optic sensor 100. The fiber optic circulator 200 is at least used to receive and transmit the light source signal generated by the laser 300. After the light source signal is received by the optical fiber circulator 200, the light source signal is transmitted to the optical fiber sensor 100 and enters the interior through the waveguide trunk 10 and propagates dispersedly to multiple waveguide branches. After the light source signal is transmitted to the first sensing unit 21, the second sensing unit 22, and the third sensing unit 23 of the optical fiber sensor 100, multiple light source detection signals are generated and reflected. The multiple light source detection signals include the first detection signal, the second detection signal, and the third detection signal. Then, the first detection signal is transmitted in the first branch 11 in the reverse direction, the second detection signal is transmitted in the second branch 12 in the reverse direction, and the third detection signal is transmitted in the third branch 13 in the reverse direction, and then converged to the waveguide trunk 10, and then transmitted from the waveguide trunk 10 to the optical fiber circulator 200, that is, the light source signal is transmitted bidirectionally in the waveguide trunk 10 and multiple waveguide branches. The incoming signal is the light source signal, and the outgoing signal is the multiple light source detection signals. After the outgoing multiple light source detection signals are transmitted to the optical fiber circulator 200 , the optical fiber circulator 200 transmits the multiple light source detection signals to the signal processing module 400 .

[0052] Please refer to Figure 5 , Figure 5 is a schematic diagram of another flow field monitoring system provided by an embodiment of the present invention. In a specific implementation of the second aspect of the present application, the optical fiber circulator 200 receives a plurality of light source detection signals generated by the optical fiber sensor 100, and transmits the plurality of light source detection signals to the signal processing module 400. The signal processing module 400 includes a photoelectric detector 410, a signal collector 420, and a computer device 430;

[0053] The photoelectric detector 410 is used to convert the multiple light source detection signals into digital electrical signals. The optical fiber circulator 200 transmits the multiple light source detection signals to the photoelectric detector 410 of the signal processing module 400. The signal collector 420 is used to collect the digital electrical signals and transmit them to the computer device 430. The computer device 430 includes a host computer. The computer device 430 is used to filter the digital electrical signals and calculate the drift of the light source signal, the external temperature change ΔT, and the external static pressure change ΔP.I , External dynamic pressure change ΔP E and flow rate u.

[0054] Please refer to Figure 6 , Figure 6 It is a work flow chart of the signal processing module 400 provided by an embodiment of the present invention, wherein the computer device 430 includes a first bandpass filter, a second bandpass filter, and a third bandpass filter. By setting the first bandpass filter, the central wavelength corresponding to the fiber Bragg grating 21a can be screened, and the central wavelength corresponding to the fiber Bragg grating 21a is 1550nm, so as to measure the change of the central wavelength with temperature for more accurate temperature measurement. By setting the second bandpass filter, the wavelength of 1330nm-1380nm can be screened, and the change of dynamic static pressure can be calculated by analyzing the resonant spectrum drift of the signal in this band, and then the flow rate of the external fluid can be calculated. By setting the third bandpass filter, the wavelength of 1430nm-1480nm can be screened, and the change of external static pressure can be calculated by analyzing the resonant spectrum drift of the signal in this band. This solution achieves decoupling of multiple light source detection signals by setting up a first bandpass filter, a second bandpass filter, and a third bandpass filter, which is beneficial for separating the first detection signal, the second detection signal, and the third detection signal, so that the flow field monitoring system measures the temperature, pressure, and external fluid detection results more accurately.

[0055] The third aspect of the present application embodiment provides a flow field monitoring method, which is applied to the multifunctional optical fiber sensor 100 described in any one of the above embodiments. Figure 7 , Figure 7 : is a flow chart of a flow field monitoring method provided by an embodiment of the present invention, wherein the flow field monitoring method comprises:

[0056] The laser 300 emits a light source signal to the optical fiber circulator 200, and transmits the light source signal to the multifunctional optical fiber sensor 100 through the optical fiber circulator 200;

[0057] The optical fiber circulator 200 receives a plurality of light source detection signals from the optical fiber sensor 100, transmits the light source detection signals to the photoelectric detector 410, and converts the light source detection signals into digital electrical signals through the photoelectric detector 410;

[0058] The digital electrical signal is collected by the signal collector 420 and transmitted to the computer device 430;

[0059] The digital electrical signal is filtered by the computer device 430, and the external temperature change ΔT and the external static pressure change ΔP are determined by calculating the drift of the light source signal. I, External dynamic pressure change ΔP E and flow rate u.

[0060] The multiple light source detection signals include a first detection signal, a second detection signal, and a third detection signal.

[0061] Please refer to Figure 6 and Figure 8 , Figure 8 yes Figure 7 In a specific implementation of the third aspect of the present application, the drift of the light source signal is calculated to determine the ambient temperature change ΔT and the ambient static pressure change ΔP. I , External dynamic pressure change ΔP E And the flow rate u includes:

[0062] Monitor the reflection spectrum formed by the first sensing unit 21 to determine the reflection spectrum drift Δλ of the fiber Bragg grating 21a 1 , and according to the reflection spectrum drift amount Δλ 1 Determine the temperature change ΔT of the external environment. Specifically, the calculation formula is as follows: Δλ 1 =A 1 *ΔT, the reflection spectrum drift of the fiber Bragg grating 21a is only related to the temperature, so the temperature value of the measured environment can be obtained by monitoring the reflection spectrum drift of the fiber Bragg grating 21a, Δλ 1 A is the reflection spectrum drift of the fiber Bragg grating 21a; 1 is the temperature coefficient of the fiber Bragg grating 21a, which can be obtained by a prior temperature calibration experiment; ΔT is the change in the ambient temperature, which can be obtained by formula 1: Δλ 1 =A 1 *ΔT is obtained, and the reflection spectrum of the fiber Bragg grating 21a corresponds to the detection signal generated by the first detection signal in the computer device 430.

[0063] Monitor the first resonance spectrum formed by the third sensing unit 23 to determine the drift Δλ of the first resonance spectrum of the open microcavity 3 , and according to the temperature change ΔT and the first resonance spectrum drift Δλ 3 Determine the external static pressure change ΔP I Specifically, the open microcavity of the third sensing unit 23 forms an FPI interferometer structure along the two end faces of the optical fiber axis, and the first resonance spectrum drifts with the change of the external temperature and static pressure. The specific calculation method is as shown in Formula 2: Δλ 3 =A 3 ΔT+B 3 ΔPI Among them, Δλ 3 is the first resonance spectrum drift of the open microcavity; A 3 is the temperature coefficient of the first resonance spectrum drift of the open microcavity, B 3 is the temperature coefficient of the first resonance spectrum drift of the open microcavity, which can be obtained by the previous temperature and pressure calibration experiment; ΔT is the change of the external ambient temperature, which can be calculated by formula 1. Therefore, the change of the external static pressure ΔP can be calculated by formula 2. I The first resonance spectrum of the open microcavity corresponds to the detection signal generated by the second detection signal in the computer device 430.

[0064] Monitor the second resonance spectrum formed by the second sensing unit 22 to determine the second resonance spectrum drift Δλ of the closed microcavity 2 , and according to the temperature change ΔT, the external static pressure change ΔP I And the second resonance spectrum shift Δλ 2 , determine the external dynamic pressure change ΔP E Specifically, the first microcavity 22a of the second sensing unit 22 and the bottom surface of the membrane 22b form a Fabry-Perot interferometer FPI structure, and the second resonance spectrum will drift with the changes of external temperature, static pressure and dynamic pressure. The specific calculation method is as shown in Formula 3: Δλ 2 =A 2 ΔT+B 2 ΔP I +C 2 ΔP E Among them, Δλ 2 is the second resonance spectrum drift of the closed microcavity; A 2 , B 2 and C 2 are the temperature, static pressure and dynamic pressure coefficients of the second resonance spectrum drift of the closed microcavity, which can be obtained by the previous calibration experiment; ΔT is the change of the external environment temperature, which can be calculated by formula 1, and the change of the external static pressure ΔP I It can be calculated by formula 2. Therefore, substituting it into formula 3 can calculate the change of external dynamic pressure ΔP E The second resonance spectrum of the closed microcavity corresponds to a detection signal generated by the computer device 430 with the third detection signal.

[0065] According to the external dynamic pressure change ΔP E Determine the flow velocity u of the external fluid.

[0066] The flow velocity u can be calculated according to the following formula:

[0067]

[0068] Where ρ is the density of the external fluid.

[0069] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or may be indirectly connected to the other element through an intermediate element.

[0070] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0071] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0072] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0073] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0074] In the embodiments provided in the present application, it should be understood that the disclosed devices / robots and methods can be implemented in other ways. For example, the device / robot embodiments described above are merely schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0075] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0076] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0077] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A multifunctional optical fiber sensor, characterized in that: include: optical fiber; a waveguide trunk formed in the optical fiber; A plurality of waveguide branches arranged in parallel are formed in the optical fiber and communicated with the waveguide trunk; A sensor component is connected to the waveguide branch, and the sensor component is at least used to generate a variety of light source detection signals for detecting the temperature, pressure and flow velocity of the flow field.

2. The optical fiber sensor according to claim 1, characterized in that: The sensing component includes a first sensing unit, the waveguide branch includes a first branch, the first sensing unit is connected to the first branch, the first sensing unit is used to generate a first detection signal for measuring an external temperature change ΔT, the first branch extends in a direction gradually approaching the first side of the optical fiber, and the first sensing unit includes a fiber Bragg grating.

3. The optical fiber sensor according to claim 1, characterized in that: The sensing component includes a second sensing unit, the waveguide branch includes a second branch, the second sensing unit is connected to the second branch, and the second sensing unit is used to generate a measurement of the external dynamic pressure change ΔP E And a second detection signal of the external fluid flow velocity u.

4. The optical fiber sensor according to claim 4, characterized in that: The second branch extends along the direction of the waveguide trunk. The second sensing unit includes a first microcavity and a membrane. The first microcavity is connected to the second branch. The membrane is connected to the first microcavity to form a closed microcavity.

5. The optical fiber sensor according to claim 1, characterized in that: The sensing component includes a third sensing unit, the waveguide branch includes a third branch, the third sensing unit is connected to the third branch, and the third sensing unit is used to generate a measurement of the external static pressure change ΔP I The third detection signal.

6. The optical fiber sensor according to claim 5, characterized in that: The third branch extends in a direction gradually away from the first side portion of the optical fiber. The third sensing unit includes a second microcavity. An opening is provided on a side of the second microcavity away from the first side portion of the optical fiber.

7. The optical fiber sensor according to claims 1-6, characterized in that: The optical fiber includes any one of sapphire optical fiber, zirconium oxide optical fiber and lutetium oxide optical fiber.

8. A flow field monitoring system, characterized in that: The flow field monitoring system includes a fiber optic sensor, a laser, a fiber optic circulator, and a signal processing module. The fiber optic sensor is the fiber optic sensor according to any one of claims 1 to 7. The fiber optic circulator includes three ports, which are respectively connected to the laser, the signal processing module, and the fiber optic sensor. The fiber optic circulator is at least used to receive and transmit the light source signal generated by the laser.

9. The flow field monitoring system according to claim 8, characterized in that: The optical fiber circulator receives the multiple light source detection signals generated by the optical fiber sensor and transmits the multiple light source detection signals to the signal processing module. The signal processing module includes a photoelectric detector, a signal collector, and a computer device. The photoelectric detector is used to convert the multiple light source detection signals into digital electrical signals. The signal collector is used to collect the digital electrical signals and transmit them to the computer device. The computer device is used to filter the digital electrical signals and calculate the drift of the light source signal, the external temperature change ΔT, and the external static pressure change ΔP I , External dynamic pressure change ΔP E and flow rate u.

10. A flow field monitoring method, characterized in that: Using the flow field monitoring system according to claim 8 or 9, the flow field monitoring method comprises: The light source signal is emitted to the optical fiber circulator by a laser, and is transmitted to the multifunctional optical fiber sensor through the optical fiber circulator; receiving a plurality of light source detection signals from the optical fiber sensor through the optical fiber circulator, transmitting the light source detection signals to the photoelectric detector, and converting the light source detection signals into digital electrical signals through the photoelectric detector; Collecting the digital electrical signal through a signal collector and transmitting the digital signal to a computer device; The digital electrical signal is filtered by the computer device, and the external temperature change ΔT and the external static pressure change ΔP are determined by calculating the drift of the light source signal. I , External dynamic pressure change ΔP E and flow velocity u.

11. The flow field monitoring method according to claim 10, characterized in that: The drift of the light source signal is calculated to determine the ambient temperature change ΔT and the ambient static pressure change ΔP. I , External dynamic pressure change ΔP E And the flow rate u includes: Monitor the reflection spectrum formed by the first sensing unit, determine the reflection spectrum drift Δλ1 of the fiber Bragg grating, and determine the temperature change ΔT of the external environment according to the reflection spectrum drift Δλ1; Monitor the first resonance spectrum formed by the third sensing unit, determine the first resonance spectrum drift Δλ3 of the open microcavity, and determine the external static pressure change ΔP according to the temperature change ΔT and the first resonance spectrum drift Δλ3 I ; Monitor the second resonance spectrum formed by the second sensing unit, determine the drift Δλ2 of the second resonance spectrum of the closed microcavity, and according to the temperature change ΔT, the external static pressure change ΔP I and the second resonance spectrum drift Δλ2, to determine the external dynamic pressure change ΔP E ; According to the external dynamic pressure change ΔP E Determine the flow velocity u of the external fluid.

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