CN114812851B - Complex flow multi-channel distributed measurement device and method based on microwave domain demodulation - Google Patents
Complex flow multi-channel distributed measurement device and method based on microwave domain demodulation Download PDFInfo
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- CN114812851B CN114812851B CN202210534367.6A CN202210534367A CN114812851B CN 114812851 B CN114812851 B CN 114812851B CN 202210534367 A CN202210534367 A CN 202210534367A CN 114812851 B CN114812851 B CN 114812851B
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
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Abstract
本发明涉及一种基于微波域解调的复杂流动多路分布式测量装置，包括保偏输出宽带光源(1)、电光调制器(2)、矢量网络分析仪(3)、第一射频放大器(4)、掺铒光纤放大器(5)、光环行器(6)、1×n光纤耦合器(7)、n条传输光纤(8)、n条分布式传感光纤(9)、光电探测器(10)、第二射频放大器(11)。保偏输出宽带光源(1)的信号输出端通过保偏光纤跳线与电光调制器(2)的输入端连接；矢量网络分析仪(3)的信号输出端通过高频电缆与第一射频放大器(4)的信号输入端连接；n条分布式传感光纤(9)的纤芯中采用飞秒激光加工有连续的反射器。本发明同时提供采用此种装置实现的复杂流动多路分布式测量方法。
The present invention relates to a complex flow multi-path distributed measurement device based on microwave domain demodulation, comprising a polarization-maintaining output broadband light source (1), an electro-optic modulator (2), a vector network analyzer (3), a first radio frequency amplifier (4), an erbium-doped fiber amplifier (5), an optical circulator (6), a 1×n fiber coupler (7), n transmission optical fibers (8), n distributed sensing optical fibers (9), a photodetector (10), and a second radio frequency amplifier (11). The signal output end of the polarization-maintaining output broadband light source (1) is connected to the input end of the electro-optic modulator (2) through a polarization-maintaining optical fiber jumper; the signal output end of the vector network analyzer (3) is connected to the signal input end of the first radio frequency amplifier (4) through a high-frequency cable; and a continuous reflector is processed in the core of the n distributed sensing optical fibers (9) using a femtosecond laser. The present invention also provides a complex flow multi-path distributed measurement method implemented by using such a device.
Description
Technical Field
The invention belongs to the field of complex flow detection, and particularly relates to a complex flow multipath distributed measurement device and method based on microwave domain demodulation.
Background
In many industries using two-phase and multiphase flows as media, in order to ensure the safety, stability and reliability of the production operation process, and in order to design, perfect and improve the production device and process, it is necessary to accurately measure multiple flow characteristic parameter information of the complex flow, and flow characteristic distribution information in a certain distance or even the whole area along the fluid flow direction, and therefore, it is often necessary to realize spatially continuous distributed measurement on the complex flow characteristic parameters in the same pipeline and different pipelines and in different circumferential positions along the flow direction. Therefore, the method has important significance for multi-path spatially continuous distributed simultaneous measurement of flow characteristic parameters of complex flows such as two-phase and multiphase flows.
The existing two-phase and multiphase flow and other complex flow distributed detection technology is mainly an optical fiber sensing technology based on an optical fiber Bragg grating. The complex flow detection technology based on the fiber Bragg grating mainly carries out measurement through a plurality of fiber Bragg grating sensing units processed in a sensing fiber, has a measurement blind area and belongs to quasi-distributed measurement. This technique does not enable spatially continuous distributed measurement of flow characteristic parameters of a complex flow along the fiber. With the development of laser and optical fiber sensing technology, the advantages of electric insulation, electromagnetic interference resistance, corrosion resistance, long distance, large range, high sensitivity and the like are widely researched and applied. The currently commonly used distributed optical fiber sensing technology mainly comprises an optical time domain reflection technology based on Rayleigh scattering, a distributed measurement technology based on Raman scattering, an optical time domain reflection technology based on Brillouin scattering, an optical time domain analysis technology, an optical coherence domain analysis technology and an optical coherence domain reflection technology. The distributed measurement technology based on Raman scattering is sensitive to temperature only and is mainly used for measuring temperature, the signal of the reflection technology based on self-Brillouin scattering is weak, so that signal to noise ratio is low, the optical time domain technology based on a pulse light source is limited by phonon service life and has low spatial resolution, and the optical coherence domain measurement technology based on a low coherence light source can realize distributed measurement by scanning sensing positions one by one. These severely limit the application of existing distributed fiber optic sensing technology to distributed measurement of flow characteristics of two-phase and multiphase flows.
Based on this, it is necessary to invent a new complex flow test technique to solve the existing problem of spatially continuous distributed simultaneous measurement in the flow direction at multiple locations within the same pipe and different pipes.
Disclosure of Invention
The invention provides a complex flow multipath distributed measurement device and a method based on microwave domain demodulation, which can realize the spatially continuous multipath distributed measurement of the flow parameters of a complex flow field.
The invention is realized by adopting the following technical scheme:
The complex flow multipath distributed measuring device based on microwave domain demodulation is characterized by comprising a polarization-maintaining output broadband light source (1), an electro-optical modulator (2), a vector network analyzer (3), a first radio frequency amplifier (4), an erbium-doped optical fiber amplifier (5), an optical circulator (6), a1 Xn optical fiber coupler (7), n transmission optical fibers (8), n distributed sensing optical fibers (9), a photoelectric detector (10), a second radio frequency amplifier (11) and a computer (12),
The signal output end of the polarization maintaining output broadband light source (1) is connected with the input end of the electro-optic modulator (2) through a polarization maintaining optical fiber jumper, the signal output end of the vector network analyzer (3) is connected with the signal input end of the first radio frequency amplifier (4) through a high-frequency cable, the signal output end of the first radio frequency amplifier (4) is connected with the signal input end of the electro-optic modulator (2) through a high-frequency cable, the output end of the electro-optic modulator (2) is connected with the input end of the erbium-doped optical fiber amplifier (5) through an optical fiber jumper, the output end of the erbium-doped optical fiber amplifier (5) is connected with the signal input end of the optical circulator (6) through an optical fiber jumper, the reflecting end of the optical circulator (6) is connected with the input end of the 1×n optical fiber coupler (7), the n emergent ends of the 1×n optical fiber coupler (7) are respectively connected with n transmission optical fibers (8), the signal output end of the optical fiber (6) is connected with the signal input end of the electro-optic modulator (9) through a high-frequency cable, the signal output end of the optical fiber amplifier (6) is connected with the output end of the high-speed optical fiber detector (10) through a high-frequency cable (11) through a high-frequency detector, the signal output end of the second radio frequency analyzer (11) is connected with the signal input end of the high-frequency amplifier (11) through the high-frequency amplifier, the vector network analyzer (3) is connected with the computer (12) through a high-frequency cable;
The optical cores of the N distributed sensing optical fibers (9) are processed by femtosecond laser, the optical path difference corresponding to the distance between adjacent reflectors is larger than the coherence length of a broadband light source and smaller than the coherence length of a microwave signal generated by a vector network analyzer, the length of the N transmission optical fiber is larger than the length of the N-1 transmission optical fiber plus the length of the N-1 sensing optical fiber, wherein N is larger than or equal to 2, and N is the maximum value of N.
Further, n sensing optical fibers (9) are respectively selected from different types of optical fibers according to actual requirements, and reflectors with different numbers and adjacent intervals are designed and processed.
Further, n sensing optical fibers (9) are arranged inside a single pipeline or respectively arranged on the inner walls of different pipelines, and the number of the arranged inner walls of each pipeline is determined according to actual conditions.
The invention also provides a complex flow multipath distributed measurement method based on microwave domain demodulation, which is realized in the complex flow multipath distributed measurement device based on microwave domain demodulation, and the method is realized by adopting the following steps:
The method comprises the steps of enabling an optical signal output by a polarization-maintaining output broadband light source to enter an electro-optical modulator, enabling a microwave signal output by a vector network analyzer to enter the electro-optical modulator after being amplified by a first radio frequency amplifier, enabling the microwave signal to be modulated by the electro-optical modulator and then loaded on the optical signal, enabling the optical signal modulated by the microwave signal to enter an erbium-doped optical fiber amplifier after being output by the electro-optical modulator and then being amplified by the erbium-doped optical fiber amplifier and then being input into an optical circulator, enabling the optical signal to enter a1 Xn optical fiber coupler after being output by a reflecting end of the optical circulator, enabling the optical signal to be divided into n paths after passing through the 1 Xn optical fiber coupler, enabling n optical signals to enter n paths of sensing optical fibers through n transmission optical fibers respectively, enabling the reflected microwave envelope of the optical signal to be reflected at the position where the optical signal meets, enabling the interference signal to enter a high-speed photoelectric detector after being output from an emergent end of the optical circulator, enabling the interference signal to enter a second radio frequency amplifier after being amplified by the second radio frequency amplifier, enabling the optical signal to be input into a computer by the vector network analyzer. And the interference spectrum of the microwave signal can be obtained by carrying out frequency sweep on the microwave signal output by the vector network analyzer. The sensing optical fiber is influenced by pressure, temperature and other factors of complex flow such as two-phase flow and multiphase flow, the length and refractive index of the optical fiber at the corresponding position can be changed, so that the optical path of an optical signal reflected by the reflector is changed, and the interference spectrum of a microwave envelope signal can be shifted. The parameters such as complex flow pressure, temperature and the like of two-phase and multiphase flow have a corresponding relation with the optical path change quantity, the optical path change quantity has a corresponding relation with the microwave interference spectrum frequency shift quantity, and then the flow parameters to be measured can be obtained through inversion of the microwave interference spectrum frequency shift quantity.
The method comprises the steps of obtaining space distribution information of reflected signals by transforming acquired microwave interference spectrums from a frequency domain to a time domain, distinguishing a reflected signal interval corresponding to each sensing optical fiber reflector according to the actual lengths of n sensing optical fibers and transmission optical fibers connected with the sensing optical fibers, selecting two required reflected signals by utilizing a rectangular window function to remove other reflected signals, reconstructing the microwave interference spectrums of the two selected reflected signals through Fourier transformation, and further demodulating complex flow parameters such as two-phase and multiphase flow at corresponding positions by respectively reconstructing the microwave interference spectrums corresponding to adjacent reflectors of n distributed sensing optical fibers, so that multi-path space continuous distributed simultaneous measurement of complex flow characteristic parameters is realized.
Compared with the existing two-phase and multiphase flow testing technology, the complex flow multipath distributed measuring device and method based on microwave domain demodulation have the following advantages:
1. Compared with the existing multiphase flow detection technology, the complex flow multipath distributed measurement device and method based on microwave domain demodulation can realize continuous long-distance distributed simultaneous measurement of multiphase flow characteristic parameter space along the flow direction at a plurality of positions in the same pipeline and different pipelines by adopting a single sensing system.
2. The complex flow multipath distributed measuring device and method based on microwave domain demodulation, provided by the invention, are based on a microwave photon technology, take optical signals as carriers of microwave signals, and have the advantages of insensitivity to optical fiber types, high signal quality, low processing quality requirements on sensing optical fiber internal reflectors and the like.
3. According to the complex flow multipath distributed measuring device and method based on microwave domain demodulation, when in measurement, each path of sensing optical fiber can respectively adopt the same or different types of waveguides according to actual requirements, and reflectors with the same or different numbers and intervals are processed, so that the complex flow multipath distributed measuring device and method based on microwave domain demodulation have the characteristics of high flexibility, strong adaptability and the like.
The invention effectively solves the problem that the prior complex flow test technology can not realize the spatially continuous distributed measurement of different circumferential positions in the same pipeline or different pipelines along the flow direction.
Drawings
Fig. 1 is a schematic structural diagram of a complex flow multi-path distributed measurement device based on microwave domain demodulation according to the present invention.
FIG. 2 is an exemplary diagram of a multi-channel distributed sensing fiber arrangement in a single channel in an apparatus according to the present invention.
Fig. 3 is a schematic diagram of the device according to the present invention, in which multiple distributed sensing fibers are respectively arranged in multiple pipes (three pipes and three sensing fibers are taken as examples).
FIG. 4 is a schematic diagram of the method of the present invention for extracting the reflected signals from adjacent reflectors using a rectangular window function.
FIG. 5 is a schematic diagram of a reconstructed microwave interference spectrum in the method of the present invention.
The system comprises a 1-polarization maintaining output broadband light source, a 2-electro-optic modulator, a 3-vector network analyzer, a 4-first radio frequency amplifier, a 5-erbium-doped fiber amplifier, a 6-optical circulator, a 7-1 Xn fiber coupler, 8-n transmission fibers, 9-n distributed sensing fibers, a 10-photoelectric detector, a 11-second radio frequency amplifier, a 12-computer, a 13-pipeline, a 14-horizontal pipeline, a 15-inclined pipeline and a 16-vertical pipeline.
Detailed Description
The complex flow multipath distributed measuring device based on microwave domain demodulation comprises a polarization maintaining output broadband light source 1, an electro-optical modulator 2, a vector network analyzer 3, a first radio frequency amplifier 4, an erbium-doped optical fiber amplifier 5, an optical circulator 6, a1×n optical fiber coupler 7, n transmission optical fibers 8, n distributed sensing optical fibers 9, a photoelectric detector 10, a second radio frequency amplifier 11 and a computer 12.
The signal output end of the polarization-maintaining output broadband light source 1 is connected with the input end of the electro-optic modulator 2 through a polarization-maintaining optical fiber jumper, the signal output end of the vector network analyzer 3 is connected with the signal input end of the first radio-frequency amplifier 4 through a high-frequency cable, the signal output end of the first radio-frequency amplifier 4 is connected with the signal input end of the electro-optic modulator 2 through a high-frequency cable, the output end of the electro-optic modulator 2 is connected with the input end of the erbium-doped optical fiber amplifier 5 through an optical fiber jumper, the output end of the erbium-doped optical fiber amplifier 5 is connected with the signal input end of the optical circulator 6 through an optical fiber jumper, the reflecting end of the optical circulator 6 is connected with the incident end of the 1×n optical fiber coupler 7, the n emergent ends of the 1×n optical fiber coupler 7 are respectively connected with the n transmission optical fibers 8, the n transmission optical fibers 8 are connected with the n distributed sensing optical fibers 9, the signal output end of the optical circulator 6 is connected with the incident end of the high-speed optical fiber detector 10 through an optical fiber jumper, the output end of the high-speed optical fiber detector 10 is connected with the signal input end of the second radio-frequency amplifier 11 through an optical fiber jumper, the output end of the high-speed optical fiber detector 10 is connected with the signal input end of the vector network analyzer 3 through the high-frequency analyzer 12, and the vector network analyzer is connected with the input end of the vector analyzer 3 through the high-frequency network analyzer.
Wherein, the cores of the n distributed sensing optical fibers 9 are processed by femtosecond laser, and the optical path difference corresponding to the distance between adjacent reflectors is larger than the coherence length of the broadband light source and smaller than the coherence length of the microwave signal generated by the vector network analyzer.
In the specific implementation, the length of the nth transmission optical fiber is longer than the length of the nth transmission optical fiber plus the nth sensing optical fiber and the nth sensing optical fiber, wherein N is more than or equal to 2, and N is the maximum value of N.
In practical implementation, the n sensing optical fibers 9 can respectively select different types of optical fibers according to practical requirements, and design and process reflectors with different numbers and adjacent intervals.
In practical implementation, n sensing optical fibers 9 can be simultaneously arranged inside a single pipeline as shown in fig. 2, or respectively arranged on the inner walls of different pipelines as shown in fig. 3, and the arrangement number of the inner walls of each pipeline can be determined according to practical situations.
The invention discloses a complex flow multipath distributed measurement method based on microwave domain demodulation, which is realized in the complex flow multipath distributed measurement device based on microwave domain demodulation, and the method is realized by adopting the following steps:
The optical signal output by the polarization-maintaining output broadband light source 1 enters the electro-optical modulator 2, the microwave signal output by the vector network analyzer 3 enters the electro-optical modulator 2 after being amplified by the first radio frequency amplifier 4, the microwave signal is modulated by the electro-optical modulator 2 and then loaded on the optical signal, the optical signal modulated by the microwave signal enters the erbium-doped optical fiber amplifier 5 after being output by the electro-optical modulator 2 and then is amplified by the erbium-doped optical fiber amplifier 5 and then enters the optical circulator 6, the optical signal enters the 1 x n optical fiber coupler 7 after being output by the reflecting end of the optical circulator 6 and then is divided into n paths by the 1 x n optical fiber coupler 7, the n paths of optical signals respectively enter the n sensing optical fibers 9 through the n transmission optical fibers 8, reflection occurs at the reflectors in the sensing optical fibers, the microwave envelope of the reflected optical signals interferes at the meeting position, the interference signal enters the high-speed photoelectric detector 10 after being output from the emergent end of the optical circulator 6, enters the second radio frequency amplifier 11 after being converted into the high-speed electric signal by the high-speed photoelectric detector 10, and then enters the second radio frequency amplifier 11 after being amplified by the second radio frequency amplifier 11, and then is acquired by the vector network analyzer 3, and the interference information is acquired by the vector network analyzer 3 and is input to the computer analyzer 12. The interference spectrum of the microwave signal can be obtained by sweeping the frequency of the microwave signal output by the vector network analyzer 3. The sensing optical fiber is influenced by pressure, temperature and other factors of complex flow such as two-phase flow and multiphase flow, the length and refractive index of the optical fiber at the corresponding position can be changed, so that the optical path of an optical signal reflected by the reflector is changed, and the interference spectrum of a microwave envelope signal can be shifted. The parameters such as complex flow pressure, temperature and the like of two-phase and multiphase flow have a corresponding relation with the optical path change quantity, the optical path change quantity has a corresponding relation with the microwave interference spectrum frequency shift quantity, and then the flow parameters to be measured can be obtained through inversion of the microwave interference spectrum frequency shift quantity.
The method comprises the steps of obtaining space distribution information of reflected signals by transforming acquired microwave interference spectrums from a frequency domain to a time domain, distinguishing a reflected signal interval corresponding to each sensing optical fiber reflector according to the actual lengths of n sensing optical fibers and transmission optical fibers connected with the sensing optical fibers, selecting two required reflected signals by utilizing a rectangular window function to remove other reflected signals, reconstructing the microwave interference spectrums of the two selected reflected signals through Fourier transformation, and reconstructing the microwave interference spectrums corresponding to adjacent reflectors of the n distributed sensing optical fibers respectively, wherein the complex flow parameters such as two-phase flow and multiphase flow at corresponding positions can be demodulated, and therefore multi-path space continuous distributed simultaneous measurement of the complex flow characteristic parameters is achieved.
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