CN106949860B - Pipeline inner wall detection system and method - Google Patents

Abstract

The invention provides a pipeline inner wall detection system and method, which relate to the technical field of microwave detection. The system includes: a vector network analyzer device, a coaxial feed end cover device and a terminal short-circuit end cover. The input end of the coaxial feed end cover device is connected to the vector network analyzer device, and the output end of the coaxial feed end cover device is used to be connected to one end of the pipeline to be tested. The terminal short-circuit end cap is used to connect to the other end of the pipeline to be tested, so that the coaxial feeding end cap device and the terminal short-circuit end cap respectively close the two ends of the pipeline to be tested to form a microwave resonant cavity. In this way, a microwave resonant cavity is formed through long-distance transmission of microwaves in the pipeline to be tested, and long-distance detection of the pipeline to be tested is realized.

Description

Pipeline inner wall detection system and method

technical field

The invention relates to the technical field of microwave detection, in particular to a pipeline inner wall detection system and method.

Background technique

Metal pipes are widely used in industrial production, such as oil and gas transmission, chemical industry, nuclear industry and other fields. If the thinning of the inner wall of the pipeline cannot be discovered and dealt with in time, it will cause serious damage to the leakage of the transported materials. Therefore, the detection of inner wall thinning of metal pipes and the evaluation of pipe life are very important. In recent years, the detection methods applied to metal pipelines mainly include: ray method, ultrasonic method, eddy current detection method, etc. However, except for ultrasonic guided wave testing, the above-mentioned various methods can only evaluate the local area where the testing device is placed, which means that it takes more time and labor compared with long-distance pipeline testing. In addition, the attenuation of the ultrasonic guided wave is serious at the weld of the pipeline, and the surrounding environment of the pipeline also directly affects the attenuation of the ultrasonic guided wave. At present, there is no better solution to realize the long-distance detection of pipelines.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a pipeline inner wall detection system and method, which can improve the above problems. In order to achieve the above object, the technical scheme that the present invention takes is as follows:

In a first aspect, an embodiment of the present invention provides a pipeline inner wall detection system, the system comprising: a vector network analyzer device, a coaxial feed end cap device and a terminal short-circuit end cap. The input end of the coaxial feed end cover device is connected to the vector network analyzer device, and the output end of the coaxial feed end cover device is used to be connected to one end of the pipeline to be tested. The terminal short-circuit end cap is used to connect to the other end of the pipeline to be tested, so that the coaxial feeding end cap device and the terminal short-circuit end cap respectively close the two ends of the pipeline to be tested to form a microwave resonant cavity. The vector network analyzer device is used to output microwaves and transmit the microwaves to the coaxial feeding end cover device. The coaxial feeding end cover device is used for propagating the received microwave into the pipeline to be tested, and receiving standing waves, the standing waves are directed from the microwave to the terminal short-circuit end cover The transmitted part and the part reflected back through the short-circuit end cap of the terminal are superimposed to form. The coaxial feed end cover device is also used to transmit the received standing wave to the vector network analyzer device. The vector network analyzer device is also used to process the standing wave to obtain the inner wall thickness of the pipeline to be tested.

In a preferred embodiment of the present invention, the above-mentioned vector network analyzer device includes a vector network analyzer and a computing terminal electrically connected to the vector network analyzer. The vector network analyzer is connected with the coaxial feed end cover device. The vector network analyzer is used to output microwaves and transmit the microwaves to the coaxial feeding end cover device. The vector network analyzer is also used to process the standing wave to obtain the first resonant frequency of the pipeline under test. The computing terminal is used to process the acquired first resonance frequency of the pipeline to be tested to obtain the inner wall thickness of the pipeline to be tested.

In a preferred embodiment of the present invention, the coaxial feed end cover device includes an antenna and a coaxial feed end cover. The joint end of the antenna is connected with the vector network analyzer. A through hole is provided on the coaxial feed end cover, and the transceiver end of the antenna is used to pass through the through hole and extend into the pipe to be tested. The output end of the coaxial feeder end cap is used to connect to one end of the pipeline to be tested, so that the coaxial feeder end cap and the terminal short-circuit end cap respectively close the two ends of the pipeline to be tested to form a microwave resonant cavity. The antenna is used to propagate the received microwave into the pipeline to be tested, and to receive a standing wave, the standing wave is transmitted from the part of the microwave along the direction to the terminal short-circuit end cover and passes through the terminal The sections reflected back from the shorted end caps are superimposed. The antenna is also used to transmit the received standing wave to the vector network analyzer.

In a preferred embodiment of the present invention, the connector end of the above-mentioned antenna is connected to the vector network analyzer through a cable, and the shell of the transmitting and receiving end of the antenna is connected to the input end of the coaxial feed end cover through conductive silver glue. electrical connection.

In a preferred embodiment of the present invention, the aforementioned antenna is a coaxial antenna. The cables are coaxial cables.

In a preferred embodiment of the present invention, the output end of the coaxial feed end cap is used to be screwed to one end of the pipeline to be tested. The terminal short-circuit end cap is used to be screwed to the other end of the pipeline to be tested.

In the second aspect, the embodiment of the present invention provides a method for detecting the inner wall of a pipeline, which is applied to the above-mentioned system, and the method includes: the vector network analyzer device outputs microwaves and transmits the microwaves to the coaxial feeder End cover device; the coaxial feed end cover device propagates the received microwave into the pipeline to be tested, and receives standing waves, and the standing waves travel from the center of the microwave to the short-circuit end of the terminal The part transmitted in the direction of the cover and the part reflected back via the terminal short-circuit end cover are superimposed; the coaxial feed end cover device also transmits the received standing wave to the vector network analyzer device; the vector network The analyzer device also processes the standing wave to obtain the inner wall thickness of the pipe to be tested

An embodiment of the present invention provides a system and method for detecting the inner wall of a pipeline. The system includes: a vector network analyzer device, a coaxial feeding end cap device and a terminal short-circuit end cap. The input end of the coaxial feed end cover device is connected to the vector network analyzer device, and the output end of the coaxial feed end cover device is used to be connected to one end of the pipeline to be tested. The terminal short-circuit end cap is used to connect to the other end of the pipeline to be tested, so that the coaxial feeding end cap device and the terminal short-circuit end cap respectively close the two ends of the pipeline to be tested to form a microwave resonant cavity. The vector network analyzer device is used to output microwaves and transmit the microwaves to the coaxial feeding end cover device. The coaxial feeding end cover device is used for propagating the received microwave into the pipeline to be tested, and receiving standing waves, the standing waves are directed from the microwave to the terminal short-circuit end cover The transmitted part and the part reflected back through the short-circuit end cap of the terminal are superimposed to form. The coaxial feed end cover device is also used to transmit the received standing wave to the vector network analyzer device. The vector network analyzer device is also used to process the standing wave to obtain the inner wall thickness of the pipeline to be tested. In this way, a microwave resonant cavity is formed through long-distance transmission of microwaves in the pipeline to be tested, and long-distance detection of the pipeline to be tested is realized.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is an application environment of the pipeline inner wall detection system provided by the first embodiment of the present invention;

Fig. 2 is a structural schematic view before and after perturbation of the cavity in the pipeline inner wall detection system provided by the first embodiment of the present invention;

Fig. 3 is another application environment of the pipeline inner wall detection system provided by the first embodiment of the present invention;

FIG. 4 is a schematic diagram of the frequency sweep experiment results provided by the first embodiment of the present invention;

Fig. 5 is a schematic diagram of resonance frequency offset and thinning thickness data provided by the first embodiment of the present invention;

Fig. 6 is a schematic diagram of the measured value and actual value data of the equivalent volume of the thinned inner wall of the pipe to be tested provided by the first embodiment;

Fig. 7 is a flow chart of a method for detecting the inner wall of a pipeline provided by the second embodiment of the present invention.

In the figure: 100-vector network analyzer device; 101-vector network analyzer; 102-computing terminal; 103-cable; 110-coaxial feed end cover device; 111-antenna; 111c-shell; 112-coaxial feed end cover; 120-terminal short-circuit end cover; 200-pipeline to be tested; 210-unthinned pipe fitting; 220-thinned pipe fitting.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "inner", "parallel" etc. is based on the orientation or positional relationship shown in the drawings, or is the The usual orientation or positional relationship of the invention product in use is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, therefore It should not be construed as a limitation of the present invention. Furthermore, the terms "first", "second", "third", etc. are only used to differentiate the description and should not be construed as indicating or implying relative importance.

In the description of the present invention, it should also be noted that unless otherwise specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

In addition, the terms "output", "transmission", etc. should be understood as describing a microwave signal, electrical signal processing. For example, "output" only refers to microwave signals or electrical signals undergoing microwave or electrical changes after passing through the equipment, instrument or device, so that the microwave signals or the electrical signals are processed to obtain the implementation technical solution Or signals needed to solve technical problems.

In the accompanying drawings of specific embodiments of the present invention, in order to better and more clearly describe the working principles of the various equipment, instruments and devices in the pipeline inner wall detection system, and express the general logic of microwave signals or electrical signals in the system, only Clearly distinguishing the relative positional relationship between various equipment, instruments, and devices does not constitute a limitation on microwaves, circuit directions, and the size, size, and shape of equipment and instruments.

first embodiment

Please refer to FIG. 1 , the present embodiment provides a detection system for the inner wall of a pipeline, the system includes: a vector network analyzer device 100 , a coaxial feed end cap device 110 and a terminal short-circuit end cap 120 . The input end of the coaxial feeding end cap device 110 is connected to the vector network analyzer device 100 , and the output end of the coaxial feeding end cap device 110 is used to connect to one end of the pipeline 200 to be tested. The terminal short-circuit end cap 120 is used to connect to the other end of the pipeline to be tested 200, so that the coaxial power supply end cap device 110 and the terminal short-circuit end cap 120 respectively close the two ends of the pipeline to be tested 200 constitute a microwave resonator.

The pipe to be tested 200 may be a metal pipe. For example, the pipeline to be tested 200 may be but not limited to a copper pipeline. If the metal pipe is regarded as a cylindrical waveguide, the microwave can be transmitted for a long distance inside the metal pipe with less attenuation, and the remote detection of the pipe can be realized.

The vector network analyzer device 100 is used to output microwaves and transmit the microwaves to the coaxial feeding end cover device 110 . Microwaves can be electromagnetic waves with a frequency of 300MHz to 300GHz, which is an abbreviation for a limited frequency band in radio waves.

The coaxial feeding end cover device 110 is used to propagate the received microwave into the pipeline 200 to be tested, and to receive a standing wave, and the standing wave travels from the middle edge of the microwave to the terminal short-circuit end The part transmitted in the direction of the cover 120 and the part reflected back through the terminal short-circuit end cover 120 are superimposed and formed. The direction along the terminal short-circuit end cap 120 is the z direction marked in FIG. 1 . The z direction is also the axial direction of the pipe 200 to be tested. The radial direction of the pipeline 200 to be tested is the p direction shown in FIG. 1 . It can be understood that the pipeline 200 to be tested can be regarded as a circular waveguide, the radial plane takes the radial center as the origin, and is formed by the intersection of the x direction and the x direction. The y-direction component of degrees.

In this embodiment, the standing wave is an electromagnetic wave of TM _0n mode.

The coaxial feed end cover device 110 is also used to transmit the received standing wave to the vector network analyzer device 100 .

The vector network analyzer device 100 is also used to process the standing wave to obtain the inner wall thickness of the pipeline 200 to be tested.

As an implementation manner, the vector network analyzer device 100 may include a vector network analyzer 101 and a computing terminal 102 electrically connected to the vector network analyzer 101 . The vector network analyzer 101 is connected to the input end of the coaxial feed end cover device 110 . The computing terminal 102 may be a processor integrated in the vector network analyzer 101, or may be a terminal device with computing functions, such as a computer, a tablet computer, a mobile phone, and the like.

The vector network analyzer 101 is used to output microwaves and transmit the microwaves to the coaxial feeding end cover device 110 . As an implementation manner, according to the size of the pipeline 200 to be tested, such as inner diameter and length, an appropriate sweep frequency range is selected, that is, the frequency range of the microwave output by the vector network analyzer 101 . In this embodiment, the frequency range of the microwave may be 13.99 GHz˜14.09 GHz.

The vector network analyzer 101 is also used for receiving the standing wave transmitted by the coaxial feed end cover device 110 .

The vector network analyzer 101 is also used for processing the standing wave to obtain the first resonant frequency of the pipeline under test 200 .

The computing terminal 102 is used to process the acquired first resonant frequency of the pipeline to be tested 200 to obtain the inner wall thickness of the pipeline to be tested 200 .

As an implementation manner, the coaxial feed end cover device 110 may include an antenna 111 and a coaxial feed end cover 112 . The connector end 111 a of the antenna 111 is connected to the vector network analyzer 101 . The coaxial feed end cover 112 is provided with a through hole, preferably, a through hole is provided at a central point of the coaxial feed end cover 112 . The transceiver end 111b of the antenna 111 is used to pass through the through hole and extend into the pipeline 200 to be tested. Preferably, the transmitting and receiving end 111b of the antenna 111 is parallel to or coincident with the axis of the pipeline 200 to be tested. The output end of the coaxial feed end cover 112 is used to connect to one end of the pipeline to be tested 200, so that the coaxial feed end cover 112 and the terminal short-circuit end cover 120 respectively close the pipeline to be tested The two ends of 200 form a microwave resonant cavity.

Furthermore, the antenna 111 is used to propagate the received microwaves into the pipeline 200 to be tested, and to receive standing waves, which are transmitted from the microwaves along the direction to the terminal short-circuit end cap 120 The part and the part reflected back through the terminal short-circuit end cap 120 are superimposed and formed. The antenna 111 is used to transmit the received microwaves to propagate into the pipeline 200 to be tested. The antenna 111 is also used to transmit the received standing wave to the vector network analyzer 101 .

As an implementation manner, the connector end 111 a of the antenna 111 is connected to the vector network analyzer 101 through a cable 103 . Preferably, the antenna 111 may be a coaxial antenna. The cable 103 may be a coaxial cable.

As an implementation manner, the casing 111c of the transceiver end 111b of the antenna 111 is electrically connected to the input end of the coaxial feeding end cover 112 through conductive silver glue.

As an implementation manner, the output end of the coaxial feed end cap 112 is used to be screwed to one end of the pipe to be tested 200 . The terminal short-circuit end cap 120 is used to be screwed to the other end of the pipeline to be tested 200 . Preferably, both the coaxial feed end cover 112 and the terminal short-circuit end cover 120 can be made of metal materials. For example, both the coaxial feed end cover 112 and the terminal short-circuit end cover 120 may be copper covers.

Please refer to FIG. 1 and FIG. 2 together. For the microwave resonant cavity, the change of resonance frequency, etc., can be deduced by perturbation theory. The field quantities before and after perturbation satisfy Maxwell's equations and boundary conditions respectively.

Corresponding to (a) in Figure 2, before perturbation, the curl equation and boundary conditions in Maxwell’s equations are:

a _n ×E ₀ ＝0 (3)

Corresponding to (a) in Figure 2, formulas (1), (2), and (3), E ₀ is the electric field in the microwave resonant cavity before perturbation, H ₀ is the magnetic field in the microwave resonant cavity before perturbation, ω ₀ is the internal resonant angular frequency of the microwave cavity before perturbation. a _n is the unit normal vector on the inner wall surface of the cavity. Before and after the perturbation, it is assumed that the electrical parameters of the medium filled in the cavity, that is, the dielectric constant ε and magnetic permeability μ do not change. V ₀ is the volume in the microwave resonant cavity before perturbation, and S ₀ is the surface area of the inner wall in the microwave resonant cavity before perturbation.

Corresponding to (b) in Figure 2, after perturbation, the curl equation and boundary conditions in Maxwell’s equations are:

a _n ×E=0 (6)

Corresponding to (b) in Figure 2, formulas (4), (5), and (6), E is the electric field in the microwave resonator after perturbation, H is the magnetic field in the microwave resonator after perturbation, and ω is the micro The internal resonant angular frequency of the microwave resonant cavity after disturbance. a _n is the unit normal vector on the inner wall surface of the cavity. Before and after the perturbation, it is assumed that the electrical parameters of the medium filled in the cavity, that is, the dielectric constant ε and magnetic permeability μ do not change. ΔV is the perturbation volume of the microwave cavity, and ΔS is the perturbation surface area of the microwave cavity.

Corrosion occurs in the pipeline 200 to be tested, and the pipeline wall becomes thinner, and the cavity wall of the resonant cavity is perturbed outwardly, that is:

V＝V ₀ +ΔV (7)

S＝S ₀ +ΔS (8)

Based on the above formula, the shift formula of the resonant frequency of the microwave cavity before and after perturbation is:

In formula (9), Δf is the shift of the resonance frequency after perturbation, and f ₀ is the resonance frequency before perturbation.

If the frequency sweep range is between the cut-off frequencies of the TM ₀₁ mode and the TM ₀₂ mode, referring to FIG. 1 , in the cylindrical coordinate system, the z direction is also the axial direction of the pipeline 200 to be tested. The radial direction of the pipeline 200 to be tested is the p direction shown in FIG. 1 . It can be understood that the pipeline 200 to be tested can be regarded as a circular waveguide, the radial plane takes the radial center as the origin, and is formed by the intersection of the x direction and the x direction. The y-direction component of degrees. Combined with the field component formula of the constant magnetic mode, the electromagnetic field component expression of the TM ₀₁ mode in the resonator is:

Then bring the above electromagnetic field component expression into the formula (9) and deduce it to get the formula (10):

In the formula (10), l=l ₁ +l _d +l ₂ , R is the inner diameter of the pipeline 200 to be tested, i.e. the radius, l is the length of the pipeline 200 to be tested, l _d is the thinned length of the pipeline 200 to be tested, t _d is the thinned thickness of the pipeline 200 to be tested.

Further, the equivalent volume of the thinned inner wall of the pipe to be tested 200 is obtained as formula (11):

In the formula (11), f _c is the cut-off frequency, and its calculation formula corresponding to the TM ₀₁ mode is the formula (12):

In addition, the formula for calculating the resonant frequency is formula (13):

As a specific implementation manner, please refer to FIG. 3 , the pipe 200 to be tested includes an _unthinned pipe 210 and a thinned pipe 220 , l=l ₁ +ld . The material of the pipeline 200 to be tested is copper, the radius of the unthinned pipe fitting 210 is R=8.5mm, the length l ₁ =450mm, and the wall thickness is 1mm. The length l _d of the thinned pipe 220 is 17 mm, and the thinned thickness of the thinned pipe 220 is t _d . For the convenience of analysis, values are taken every 0.05 mm in the interval [0, 0.2 mm].

Set the sweep frequency range: 13.99GHz to 14.09GHz, and set the pipe thinning thickness t _d as a variable in the parametric sweep analysis. According to the formula (13), it can be known that when p=12, the first resonance frequency f ₀ =14.043GHz is just in the above frequency sweep range, therefore, the first resonance frequency 14.043GHz is used as the evaluation of the resonance frequency shift within this range benchmark. In addition, the cut-off frequency f _c =13.51 GHz is calculated according to formula (12). In the frequency sweep experiment, the vector network analyzer 101 processes the standing wave to obtain the reflection coefficient S ₁₁ of the standing wave, so as to obtain the second resonant frequency of the pipeline 200 to be tested, as shown in FIG. 4 , the abscissa is the first 1. Resonant frequency, unit GHz, ordinate is reflection coefficient S ₁₁ , from right to left, as follows: A1 means 0mm thinning, A2 means 0.05mm thinning, A3 means 0.1mm thinning, A4 means 0.15mm thinning, A5 represents a thinning of 0.2 mm. It can be seen that as the thinning size t _d increases, the second resonant frequency decreases gradually.

The theoretically calculated value of the offset of the resonant frequency is obtained by formula (10), and the measured value of the offset of the resonant frequency is determined by the thinning thickness t _d , respectively corresponding to the second resonant frequency and the first resonant frequency in Fig. 4 The difference between f ₀ =14.043GHz is obtained, the relationship between the theoretically calculated value of the offset of the resonance frequency, the measured value and the thinned thickness t _d is shown in Figure 5, and the theoretically calculated value of the offset of the resonance frequency can be seen close to the measured value.

According to the measured value of the resonant frequency shift and using the formula (11) to calculate the equivalent volume ΔV of the pipe inner wall thinning, the data shown in Figure 6 is obtained. It can be seen that the measured value is relatively close to the actual value, and the relative The error is small.

The working principle of a pipeline inner wall detection system provided by the embodiment of the present invention is as follows:

The vector network analyzer 101 outputs microwaves and transmits the microwaves to the antenna 111 . The antenna 111 propagates the received microwave into the pipeline 200 to be tested, and receives the standing wave, which is transmitted from the part of the microwave along the direction to the terminal short-circuit end cap 120 and via the The reflected portion of the terminal short-circuit end cap 120 is superimposed. The antenna 111 also transmits the received standing wave to the vector network analyzer 101 through the coaxial feed end cover 112 . The vector network analyzer 101 also receives the standing wave transmitted through the coaxial feed end cover device 110 . The vector network analyzer 101 also processes the standing wave to obtain the first resonant frequency of the pipeline under test 200 . The computing terminal 102 processes the obtained first resonant frequency of the pipeline to be tested 200 to obtain the inner wall thickness of the pipeline to be tested 200 . In this way, microwaves are transmitted over a long distance in the pipeline to be tested 200 to form a microwave resonant cavity, thereby realizing long-distance detection of the pipeline to be tested 200 .

An embodiment of the present invention provides a detection system for the inner wall of a pipeline. The system includes: a vector network analyzer device 100 , a coaxial feeder end cap device 110 and a terminal short-circuit end cap 120 . The input end of the coaxial feeding end cap device 110 is connected to the vector network analyzer device 100 , and the output end of the coaxial feeding end cap device 110 is used to connect to one end of the pipeline 200 to be tested. The terminal short-circuit end cap 120 is used to connect to the other end of the pipeline to be tested 200, so that the coaxial power supply end cap device 110 and the terminal short-circuit end cap 120 respectively close the two ends of the pipeline to be tested 200 constitute a microwave resonator. The vector network analyzer device 100 is used to output microwaves and transmit the microwaves to the coaxial feeding end cover device 110 . The coaxial feeding end cover device 110 is used to propagate the received microwave into the pipeline 200 to be tested, and to receive a standing wave, and the standing wave travels from the middle edge of the microwave to the terminal short-circuit end The part transmitted in the direction of the cover 120 and the part reflected back through the terminal short-circuit end cover 120 are superimposed and formed. The coaxial feed end cover device 110 is also used to transmit the received standing wave to the vector network analyzer device 100 . The vector network analyzer device 100 is also used to process the standing wave to obtain the inner wall thickness of the pipeline 200 to be tested. In this way, microwaves are transmitted over a long distance in the pipeline to be tested 200 to form a microwave resonant cavity, thereby realizing long-distance detection of the pipeline to be tested 200 .

second embodiment

Please refer to FIG. 7 , an embodiment of the present invention provides a method for detecting the inner wall of a pipeline, which is applied to the above-mentioned system, and the method includes:

Step S300: the vector network analyzer device outputs microwaves and transmits the microwaves to the coaxial feeding end cover device;

Step S310: The coaxial feeding end cap device propagates the received microwave into the pipeline to be tested, and receives a standing wave, and the standing wave is short-circuited from the middle edge of the microwave to the terminal end cap The part transmitted in the direction and the part reflected back through the short-circuit end cap of the terminal are superimposed to form;

Step S320: the coaxial feed end cover device also transmits the received standing wave to the vector network analyzer device;

Step S330: The VNA device also processes the standing wave to obtain the inner wall thickness of the pipeline to be tested.

As an implementation manner, based on step S330, step S330 may include substep S331, substep S332, substep S333, and substep S334.

Sub-step S331: The vector network analyzer device obtains the first resonant frequency of the pipeline under test based on the acquired inner diameter, length and first preset rules of the pipeline under test;

Further, based on Obtain the first resonance frequency of the pipeline under test; Wherein, f ₀ is the first resonance frequency of the pipeline under test, R is the inner diameter of the pipeline under test, l is the length of the pipeline under test, μ is The first preset constant, ε is the second preset constant. It can be understood that the formula (13) in the first embodiment is the first preset rule. The electrical parameters of the filling medium in the resonant cavity, ε is the electric constant ε and μ is the magnetic permeability μ.

Sub-step S332: Obtain the second resonant frequency of the pipeline under test according to the obtained standing wave;

The vector network analyzer 101 processes the standing wave to obtain the reflection coefficient S ₁₁ of the standing wave, so as to obtain the second resonant frequency of the pipeline to be tested.

Sub-step S333: comparing the first resonant frequency with the second resonant frequency, and obtaining the offset of the resonant frequency according to the comparison result;

The difference between the first resonant frequency and the second resonant frequency is used as an offset of the resonant frequency.

Sub-step S334: Obtain the equivalent volume of the thinned inner wall of the pipeline to be tested based on the acquired inner diameter, length, offset of the resonance frequency and the second preset rule, so as to obtain the The inner wall thickness of the pipe to be tested.

Further, based on The equivalent volume of the thinned inner wall of the pipeline to be tested is obtained, wherein ΔV is the equivalent volume of the thinned inner wall of the pipeline to be tested, _f0 is the first resonant frequency of the pipeline to be tested, and Δf is the frequency of the resonant frequency Offset, R is the inner diameter of the pipeline to be tested, l is the length of the pipeline to be tested, μ is a first preset constant, and ε is a second preset constant. It can be understood that the formula (11) in the first embodiment is the second preset rule.

Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working process of the method described above can refer to the corresponding process in the foregoing system embodiment, and details are not repeated here.

In a method for detecting the inner wall of a pipeline provided by an embodiment of the present invention, the vector network analyzer device outputs microwaves and transmits the microwaves to the coaxial feeding end cover device; the coaxial feeding end cover device The received microwave propagates into the pipeline to be tested, and receives a standing wave which is reflected by a part of the microwave transmitted in a direction toward the terminal short-circuit end cap and via the terminal short-circuit end cap part of the loop is superimposed and formed; the coaxial feed end cover device also transmits the received standing wave to the vector network analyzer device; the vector network analyzer device also processes the standing wave to obtain the waiting wave Measure the inner wall thickness of the pipe. In this way, a microwave resonant cavity is formed through long-distance transmission of microwaves in the pipeline to be tested, and long-distance detection of the pipeline to be tested is realized.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a kind of inner wall of the pipe detection system, which is characterized in that the system comprises: vector network analyzer device, coaxial feed Electric end cap device and terminal short circuit end cap, the input terminal of the coaxial feed end cap device and the vector network analyzer device Connection, the output end of the coaxial feed end cap device are used to be connected to one end of pipe under test, and the terminal short circuit end cap is used In the other end for being connected to the pipe under test, so that the coaxial feed end cap device and the terminal short circuit end cap seal respectively It closes the pipe under test both ends and constitutes microwave cavity；

The vector network analyzer device is for exporting microwave and by the microwave transmission to the coaxial feed end cap device；

In the microwave propagation to the pipe under test that the coaxial feed end cap device is used to receive, and receives and stay Wave, the standing wave is from edge in the microwave to the part of terminal short circuit end cap direction transmission and via the terminal short circuit end The partial stack being reflected back is covered to be formed；

The standing wave that the coaxial feed end cap device is also used to receive is transmitted to the vector network analyzer device；

The vector network analyzer device is also used to handle the standing wave to obtain the inner wall thickness situation of the pipe under test.

2. system according to claim 1, which is characterized in that the vector network analyzer device includes vector network point Analyzer and the computing terminal being electrically connected with the vector network analyzer, the vector network analyzer and the coaxial feed end Lid arrangement connection；

The vector network analyzer is for exporting microwave and by the microwave transmission to the coaxial feed end cap device；

The vector network analyzer is also used to handle the standing wave to obtain the first resonance frequency of the pipe under test；

The computing terminal is used to handle the first resonance frequency of the pipe under test got to obtain the pipe under test Inner wall thickness situation.

3. system according to claim 2, which is characterized in that the coaxial feed end cap device includes antenna and coaxial feed Electric end cap, the tip side of the antenna are connect with the vector network analyzer, are provided with through-hole on the coaxial feed end cap, The sending and receiving end of the antenna across the through-hole for extending in the pipe under test, the output end of the coaxial feed end cap For being connected to one end of the pipe under test, so that the coaxial feed end cap and the terminal short circuit end cap close off institute It states pipe under test both ends and constitutes microwave cavity；

In the microwave propagation to the pipe under test that the antenna is used to receive, and receive standing wave, the standing wave The part transmitted from edge in the microwave to terminal short circuit end cap direction and the part being reflected back via the terminal short circuit end cap Superposition is formed；

The standing wave that the antenna is also used to receive is transmitted to the vector network analyzer.

4. system according to claim 3, which is characterized in that the tip side of the antenna and the vector network analyzer It is connected by cable, the shell of the sending and receiving end of the antenna and the input terminal of the coaxial feed end cap are electrically connected by conductive silver glue It connects.

5. system according to claim 4, which is characterized in that the antenna is coaxial antenna, and the cable is coaxial line Cable.

6. system according to claim 3, which is characterized in that the output end of the coaxial feed end cap is for passing through screw thread It is connected to one end of the pipe under test, the terminal short circuit end cap is for being threadingly attached to the another of the pipe under test End.

7. a kind of inner wall of the pipe detection method, which is characterized in that be applied to system as claimed in any one of claims 1 to 6, institute The system of stating includes: vector network analyzer device, coaxial feed end cap device and terminal short circuit end cap, the coaxial feed end cap The input terminal of device is connect with the vector network analyzer device, and the output end of the coaxial feed end cap device is for connecting In one end of pipe under test, the terminal short circuit end cap is used to be connected to the other end of the pipe under test, so as to described coaxial Feed end cap device and the terminal short circuit end cap close off the pipe under test both ends and constitute microwave cavity；The method Include:

The vector network analyzer device exports microwave and by the microwave transmission to the coaxial feed end cap device；

The coaxial feed end cap device is by the microwave propagation to the pipe under test received, and receives standing wave, The standing wave is from edge in the microwave to the part of terminal short circuit end cap direction transmission and via the terminal short circuit end cap The partial stack being reflected back is formed；

The standing wave received is also transmitted to the vector network analyzer device by the coaxial feed end cap device；

The vector network analyzer device handles the standing wave also to obtain the inner wall thickness situation of the pipe under test.

8. the method according to the description of claim 7 is characterized in that the vector network analyzer device also handles the standing wave To obtain the inner wall thickness situation of the pipe under test, comprising:

Internal diameter, length and the first preset rules of the pipe under test of the vector network analyzer device based on acquisition, Obtain the first resonance frequency of the pipe under test；

The second resonance frequency of the pipe under test is obtained according to the standing wave got；

First resonance frequency and second resonance frequency are compared, the offset of resonance frequency is obtained according to comparing result；

The offset and the second preset rules of internal diameter, length, the resonance frequency based on the pipe under test got, The thinned equivalent volume of the pipe under test inner wall is obtained, to obtain the inner wall thickness situation of the pipe under test.

9. according to the method described in claim 8, it is characterized in that, the internal diameter based on the pipe under test got, Length and the first preset rules obtain the first resonance frequency of the pipe under test, comprising:

It is based onObtain the first resonance frequency of the pipe under test Rate；Wherein, f₀For the first resonance frequency of the pipe under test, R is the internal diameter of the pipe under test, and l is the pipe under test Length, μ be the first preset constant, ε be the second preset constant.

10. according to the method described in claim 9, it is characterized in that, the internal diameter based on the pipe under test got, Length, the offset of the resonance frequency and the second preset rules obtain the thinned equivalent volume of the pipe under test inner wall, Include:

It is based onObtain the thinned equivalent volume of the pipe under test inner wall, wherein Δ V is described to be measured The thinned equivalent volume of inner wall of the pipe, f₀For the first resonance frequency of the pipe under test, Δ f is the offset of the resonance frequency Amount, R are the internal diameter of the pipe under test, and l is the length of the pipe under test,μ is the first preset constant, ε For the second preset constant.