An in-pipe flow velocity measuring device and method based on multi-frequency electromagnetic ultrasonic guided waves

Abstract

The present invention provides a device and method for measuring the flow velocity inside a pipe based on multi-frequency electromagnetic ultrasonic guided waves, which relates to the fields of test measurement and non-destructive testing. In this device, the guided waves excited have a larger contact area with the fluid liquid surface, enabling full circumferential measurement of the pipeline, being less affected by foams, bubbles, and minute impurities in the pipeline liquid, with stronger system robustness and anti-interference ability; and cross-correlation calculation is introduced in the process of calculating the fluid velocity, further improving the accuracy of flow velocity measurement.

Description

Technical Field

[0001] The present invention relates to the field of test measurement and nondestructive testing, and in particular, to a device and method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves. Background Art

[0002] Pipes are mainly used for liquid storage and transportation and are widely used in fields such as petroleum, nuclear power, and metallurgy. Among them, the measurement of the fluid flow velocity in the pipe plays an important role in its safe transportation. Currently, there are many methods for measuring the flow velocity of fluid pipes. For example, there are differential pressure type, rotor type, turbine type, lobe type, vortex street type, thermal type, ultrasonic and other flow meters. The key to flow velocity measurement lies in the detection of the transit time. Conventional transit time detection methods include the threshold method and the fitting method. Among them, the threshold method is relatively simple, but is greatly affected by noise; the fitting method combines the advantages of multiple samplings, but its detection accuracy depends on the selection of the model.

[0003] In summary, there is still a problem of low accuracy in the process of flow velocity measurement in the prior art. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a device and method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves. The guided waves excited in the device have a larger contact area with the fluid surface in the pipe, can realize full circumferential measurement of the pipe, are less affected by foam, bubbles, and minute impurities in the pipe liquid, and the system has stronger robustness and anti-interference ability; and the cross-correlation calculation is introduced in the process of calculating the fluid velocity, further improving the accuracy of flow velocity measurement.

[0005] In a first aspect, an embodiment of the present invention provides a device for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves. The device is applied to the measurement of the fluid velocity in a pipe. The device for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves includes: an electromagnetic ultrasonic excitation path and a data acquisition path;

[0006] The electromagnetic ultrasonic excitation path includes: an electromagnetic ultrasonic excitation sensor, a pulse excitation module, and a function generator; wherein, the output end of the function generator is connected to the input end of the pulse excitation module; the output end of the pulse excitation module is connected to the input end of the electromagnetic ultrasonic excitation sensor; the electromagnetic ultrasonic excitation sensor is arranged on the outer wall of the pipe, and the output end of the electromagnetic ultrasonic excitation sensor transmits the generated ultrasonic guided waves into the pipe fluid;

[0007] The data acquisition path includes: an electromagnetic ultrasonic receiving sensor, a variable filter, and a data acquisition module; wherein, the electromagnetic ultrasonic receiving sensor is arranged on the outer wall of the pipeline, and the input end of the electromagnetic ultrasonic receiving sensor receives the ultrasonic guided wave generated by the electromagnetic ultrasonic excitation sensor; the output end of the electromagnetic ultrasonic receiving sensor is connected to the input end of the variable filter; the output end of the variable filter is connected to the data acquisition module;

[0008] Among them, the function generator is used to generate a pulse signal according to a preset excitation frequency;

[0009] The pulse excitation module is used to convert the pulse signal generated by the function generator into a high-power pulse excitation signal;

[0010] The electromagnetic ultrasonic excitation sensor is used to excite an ultrasonic guided wave by using the high-power pulse excitation signal generated by the pulse excitation module and incident the ultrasonic guided wave into the fluid in the pipeline;

[0011] The electromagnetic ultrasonic receiving sensor is used to receive the ultrasonic guided wave in the pipeline and obtain the received signal of the ultrasonic guided wave and its receiving time;

[0012] The variable filter is used to filter the received signal of the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor according to a preset filtering condition;

[0013] The data acquisition module is used to obtain the transit time of the ultrasonic guided wave through cross-correlation calculation according to the received signal of the ultrasonic guided wave that has been filtered and its receiving time, and determine the fluid velocity in the pipeline according to the transit time.

[0014] In some embodiments, the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves further includes: an electromagnetic ultrasonic excitation impedance matching circuit and an electromagnetic ultrasonic receiving impedance matching circuit;

[0015] Among them, the electromagnetic ultrasonic excitation impedance matching circuit is arranged in the electromagnetic ultrasonic excitation path, and the pulse excitation module is connected to the electromagnetic ultrasonic excitation sensor through the electromagnetic ultrasonic excitation impedance matching circuit; the electromagnetic ultrasonic receiving impedance matching circuit is arranged in the data acquisition path, and the electromagnetic ultrasonic receiving sensor is connected to the variable filter through the electromagnetic ultrasonic receiving impedance matching circuit;

[0016] The electromagnetic ultrasonic excitation impedance matching circuit is used to perform conjugate matching on the high-power pulse excitation signal according to a preset wavelength and transmit the matched high-power pulse excitation signal to the corresponding electromagnetic ultrasonic excitation sensor to provide energy for the electromagnetic ultrasonic excitation sensor;

[0017] The electromagnetic ultrasonic receiving impedance matching circuit is used to perform impedance matching on the voltage signal induced by the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor and transmit the matched voltage signal to the variable filter.

[0018] In some embodiments, the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves further includes: a power limiting module;

[0019] The power limiting module is arranged in the data acquisition path, and the electromagnetic ultrasonic excitation impedance matching circuit is connected to the variable filter through the power limiting module;

[0020] The power limiting module is used to limit the voltage signal according to a preset power threshold.

[0021] In some embodiments, the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves further includes: a gain amplification module;

[0022] The gain amplification module is arranged in the data acquisition path, and the power limiting module is connected to the variable filter through the gain amplification module;

[0023] The gain amplification module is used to amplify the voltage signal according to a preset gain coefficient.

[0024] In some embodiments, the electromagnetic ultrasonic excitation sensor includes: a first electromagnetic ultrasonic sensor and a second electromagnetic ultrasonic sensor;

[0025] Wherein, the ultrasonic guided wave wavelengths and excitation frequencies of the first electromagnetic ultrasonic sensor and the second electromagnetic ultrasonic sensor are not the same;

[0026] The deflection angles at which the ultrasonic guided waves of the first electromagnetic ultrasonic sensor and the second electromagnetic ultrasonic sensor are incident on the fluid are not the same.

[0027] In some embodiments, the electromagnetic ultrasonic excitation sensor includes: a flexible coil and a soft magnet;

[0028] Wherein, the flexible coil and the soft magnet group are arranged on the outer wall of the pipeline; the flexible coil and the soft magnet are arranged around the pipeline for one week; the radian of the flexible coil is the same as that of the pipeline.

[0029] In a second aspect, an embodiment of the present invention provides a method for measuring in-pipe flow velocity based on multi-frequency electromagnetic ultrasonic guided waves, and this method is applied to the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves mentioned in the first aspect; wherein, the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves includes: an electromagnetic ultrasonic excitation path and a data acquisition path; the electromagnetic ultrasonic excitation path includes: an electromagnetic ultrasonic excitation sensor, a pulse excitation module, and a function generator; the data acquisition path includes: an electromagnetic ultrasonic receiving sensor, a variable filter, and a data acquisition module;

[0030] The method for measuring in-pipe flow velocity based on multi-frequency electromagnetic ultrasonic guided waves includes:

[0031] Control the function generator to generate a pulse signal according to a preset excitation frequency;

[0032] Control the pulse excitation module to convert the pulse signal generated by the function generator into a high-power pulse excitation signal;

[0033] Control the electromagnetic ultrasonic excitation sensor to excite the received high-power pulse excitation signal to obtain an ultrasonic guided wave, and incident the ultrasonic guided wave into the fluid in the pipeline;

[0034] Control the electromagnetic ultrasonic receiving sensor to receive the ultrasonic guided wave in the fluid, and obtain the received signal of the ultrasonic guided wave and its receiving time;

[0035] Control the variable filter to filter the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor according to a preset filtering condition;

[0036] Control the data acquisition module to obtain the transit time of the ultrasonic guided wave through cross-correlation calculation according to the received signal and its receiving time corresponding to the ultrasonic guided wave after filtering, and determine the fluid velocity in the pipeline according to the transit time.

[0037] In some embodiments, the step of controlling the electromagnetic ultrasonic excitation sensor to excite the received high-power pulse excitation signal to obtain an ultrasonic guided wave, and incident the ultrasonic guided wave into the fluid in the pipeline includes:

[0038] Control the electromagnetic ultrasonic excitation sensor to excite the high-power pulse excitation signal according to the corresponding wavelength to obtain an ultrasonic guided wave including multiple phase velocities;

[0039] Determine the deflection angle between the ultrasonic guided wave in the pipeline and the fluid, and control the ultrasonic guided wave to be incident into the fluid according to the deflection angle; wherein, the deflection angle is calculated by the following formula:

[0040]

[0041] wherein, θ is the deflection angle; c f is the longitudinal wave sound velocity in the fluid; c p is the phase velocity of the ultrasonic guided wave in the pipeline.

[0042] In some embodiments, the transit time of the ultrasonic guided wave is calculated by the following formula:

[0043]

[0044] wherein, t TOF is the transit time; t fluid,v is the propagation time of the ultrasonic guided wave in the fluid with a flow velocity of v; t' pipe$t$ is the propagation time of the ultrasonic guided wave in the pipeline; $D$ is the inner diameter length of the pipeline; $L$ is the propagation distance of the ultrasonic guided wave in the pipeline; $X'$ is the position change amount of the ultrasonic guided wave in the pipeline under the moving state and the state without fluid movement; $C$ g is the group velocity of the ultrasonic guided wave in the pipeline.

[0045] In some embodiments, the position change amount of the ultrasonic guided wave in the pipeline under the moving state and the state without fluid movement is calculated by the following formula:

[0046]

[0047] wherein, $X'$ is the position change amount of the ultrasonic guided wave in the pipeline under the moving state and the state without fluid movement; $v$ is the flow velocity of the fluid.

[0048] In a third aspect, an embodiment of the present invention further provides an electronic device, including: a processor and a memory; a computer program is stored on the memory, and when the computer program is run by the processor, the steps of the in-pipe flow velocity measurement method based on multi-frequency electromagnetic ultrasonic guided waves mentioned in the second aspect above are implemented.

[0049] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, wherein when the computer program is run by the processor, the steps of the in-pipe flow velocity measurement method based on multi-frequency electromagnetic ultrasonic guided waves mentioned in the second aspect above are implemented.

[0050] The embodiments of the present invention bring the following beneficial effects:

[0051] The present invention provides a device and method for measuring the flow velocity of fluid in a pipe using multi-frequency electromagnetic ultrasonic guided waves. The device is applied to measure the fluid velocity in a pipe. The device for measuring the flow velocity of fluid in a pipe based on multi-frequency electromagnetic ultrasonic guided waves includes: an electromagnetic ultrasonic excitation path and a data acquisition path. Among them, the electromagnetic ultrasonic excitation path includes: an electromagnetic ultrasonic excitation sensor, a pulse excitation module, and a function generator. Among them, the output end of the function generator is connected to the input end of the pulse excitation module; the output end of the pulse excitation module is connected to the input end of the electromagnetic ultrasonic excitation sensor; the electromagnetic ultrasonic excitation sensor is arranged on the outer wall of the pipe, and the output end of the electromagnetic ultrasonic excitation sensor transmits the generated ultrasonic guided wave into the pipe fluid. The data acquisition path includes: an electromagnetic ultrasonic receiving sensor, a variable filter, and a data acquisition module. Among them, the electromagnetic ultrasonic receiving sensor is arranged on the outer wall of the pipe, and the input end of the electromagnetic ultrasonic receiving sensor receives the ultrasonic guided wave generated by the electromagnetic ultrasonic excitation sensor; the output end of the electromagnetic ultrasonic receiving sensor is connected to the input end of the variable filter; the output end of the variable filter is connected to the data acquisition module. The function generator is used to generate a pulse signal according to a preset excitation frequency; the pulse excitation module is used to convert the pulse signal generated by the function generator into a high-power pulse excitation signal; the electromagnetic ultrasonic excitation sensor is used to excite an ultrasonic guided wave using the high-power pulse excitation signal generated by the pulse excitation module and incident the ultrasonic guided wave into the fluid in the pipe; the electromagnetic ultrasonic receiving sensor is used to receive the ultrasonic guided wave in the pipe and obtain the received signal of the ultrasonic guided wave and its reception time; the variable filter is used to filter the received signal of the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor according to a preset filtering condition; the data acquisition module is used to obtain the transit time of the ultrasonic guided wave through cross-correlation calculation based on the received signal of the ultrasonic guided wave that has been filtered and its reception time, and determine the fluid velocity in the pipe according to the transit time. The device generates a pulse signal according to a preset excitation frequency through the function generator, and uses the pulse excitation module to convert the pulse signal generated by the function generator into a high-power pulse excitation signal and then transmits it to the electromagnetic ultrasonic excitation sensor; the electromagnetic ultrasonic excitation sensor obtains an ultrasonic guided wave according to the high-power pulse excitation signal and incident the ultrasonic guided wave into the fluid in the pipe; the electromagnetic ultrasonic receiving sensor calculates the transit time of the ultrasonic guided wave through cross-correlation calculation after receiving the ultrasonic guided wave in the fluid, and finally determines the fluid velocity in the pipe using the transit time. The contact area of the guided wave excited in the device with the fluid surface is larger, which can realize full circumferential measurement of the pipe, is less affected by foam, bubbles, and tiny impurities in the pipe liquid, and has stronger system robustness and anti-interference ability; and cross-correlation calculation is introduced in the calculation process of the fluid velocity to further improve the accuracy of flow velocity measurement.

[0052] Other features and advantages of the present invention will be set forth in the following description, or can be learned by inference from the description or be definitely determined without doubt, or can be learned by implementing the above technologies of the present invention.

[0053] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, makes a detailed description as follows. Description of the Drawings

[0054] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0055] Figure 1 Schematic diagram of a tube inner flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0056] Figure 2 Schematic diagram of another tube inner flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0057] Figure 3 Schematic diagram of a flexible coil in a tube inner flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0058] Figure 4 Schematic diagram of energy propagation in a tube inner flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0059] Figure 5 Flowchart of a tube inner flow velocity measuring method based on multi-frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0060] Figure 6 Flowchart of step S503 in a tube inner flow velocity measuring method based on multi-frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0061] Figure 7 Schematic diagram of ultrasonic energy propagation path analysis in a tube inner flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0062] Figure 8 Schematic diagram of an ultrasonic guided wave dispersion curve used in a tube inner flow velocity measuring method based on multi-frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0063] Figure 9 This is the schematic diagram of cross - correlation calculation in a method for measuring the flow velocity inside a pipe based on multi - frequency electromagnetic ultrasonic guided waves provided by an embodiment of the present invention;

[0064] Figure 10 This is the schematic structural diagram of an electronic device provided by an embodiment of the present invention.

[0065] Icon:

[0066] 100 - Electromagnetic ultrasonic excitation path; 110 - Function generator; 120 - Pulse excitation module; 130 - Electromagnetic ultrasonic excitation sensor; 140 - Electromagnetic ultrasonic excitation impedance matching circuit;

[0067] 200 - Data acquisition path; 210 - Electromagnetic ultrasonic receiving sensor; 220 - Variable filter; 230 - Data acquisition module; 240 - Electromagnetic ultrasonic receiving impedance matching circuit; 250 - Power limiting module; 260 - Gain amplification module;

[0068] 101 - Processor; 102 - Memory; 103 - Bus; 104 - Communication interface. Detailed implementation manners

[0069] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0070] Pipelines are mainly used for liquid storage and transportation and are widely applied in fields such as petroleum, nuclear power, and metallurgy. The measurement of the fluid flow velocity in pipelines plays an important role in their safe transportation. Currently, there are many methods for measuring the flow velocity of fluid pipelines. For example, there are differential pressure type, rotor type, turbine type, lobe type, vortex street type, thermal type, ultrasonic type, etc. flowmeters, but each measurement method has its own applicable range.

[0071] Ultrasonic detection has developed relatively rapidly in pipeline measurement due to its high detection accuracy, low cost, fast response, convenient installation, and non - destruction of the test piece. As a common form of ultrasonic excitation mode, ultrasonic guided waves can propagate over long distances in a waveguide structure and are very suitable for long - distance and large - range detection in long structures such as pipelines.

[0072] There are mainly two ways to excite ultrasonic guided waves in pipelines: piezoelectric ultrasonic technology and electromagnetic ultrasonic technology. Among them, piezoelectric ultrasonic detection, as one of the most commonly used ultrasonic excitation methods, is often applied to fluid flow velocity measurement. Its detection principle is that the piezoelectric crystal in the piezoelectric sensor generates a dipole phenomenon after being subjected to mechanical stress to excite ultrasonic waves. However, during the detection process, a coupling agent is required to ensure good contact with the test piece, and the surface of the test piece needs to be pretreated. It cannot be detected at high temperatures, and the presence of bubbles or minute impurities in the fluid will also affect the results of piezoelectric ultrasound.

[0073] Electromagnetic ultrasonic detection does not require a coupling agent compared to piezoelectric ultrasonic detection and can be measured in harsh environments such as high and low temperatures. The electromagnetic ultrasonic sensor consists of a magnet and a coil. By designing the configuration of the static and dynamic magnetic fields and the structure of the coil and magnet, different mode guided waves can be excited and generated inside the test piece. Each wire in the coil of the electromagnetic ultrasonic sensor is an array element, so the electromagnetic ultrasonic sensor is equivalent to an array sensor. Compared with the piezoelectric ultrasonic sensor, the electromagnetic ultrasonic sensor has a wider excitation range and is less affected by minute impurities on the liquid surface. And by designing the flexible coil and soft magnet of the sensor, it can better fit the curved surface of the pipeline structure.

[0074] The key to flow velocity measurement lies in the detection of the transit time. Conventional transit time detection methods include the threshold method and the fitting method. Among them, the threshold method is relatively simple, but is greatly affected by noise; the fitting method integrates the advantages of multiple samplings, but its detection accuracy depends on the selection of the model. To sum up, there is still a problem of low accuracy in the process of flow velocity measurement in the existing technology. Based on this, the embodiments of the present invention provide a device and method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves. The guided waves excited in this device have a larger contact area with the fluid liquid surface, can achieve full circumferential measurement of the pipeline, are less affected by the foam, bubbles, and minute impurities in the pipeline liquid, and the system has stronger robustness and anti-interference ability; and the cross-correlation calculation is introduced in the process of calculating the fluid velocity, further improving the accuracy of flow velocity measurement.

[0075] To facilitate the understanding of this embodiment, first, a device for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves disclosed in the embodiments of the present invention will be introduced in detail. This device is applied to the measurement of the fluid velocity in a pipeline, such as Figure 1As shown in the figure, the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves includes: an electromagnetic ultrasonic excitation path 100 and a data acquisition path 200; the electromagnetic ultrasonic excitation path 100 includes: a function generator 110, a pulse excitation module 120, and an electromagnetic ultrasonic excitation sensor 130; wherein, the output end of the function generator 110 is connected to the input end of the pulse excitation module 120; the output end of the pulse excitation module 120 is connected to the input end of the electromagnetic ultrasonic excitation sensor 130; the electromagnetic ultrasonic excitation sensor 130 is arranged on the outer wall of the pipeline, and the output end of the electromagnetic ultrasonic excitation sensor 130 transmits the generated ultrasonic guided wave into the pipeline. Among them, the function generator 110 is used to generate a pulse signal according to a preset excitation frequency; the pulse excitation module 120 is used to convert the pulse signal generated by the function generator into a high-power pulse excitation signal; the electromagnetic ultrasonic excitation sensor 130 is used to excite ultrasonic guided waves by using the high-power pulse excitation signal generated by the pulse excitation module 120 and incident the ultrasonic guided waves into the fluid in the pipeline.

[0076] The data acquisition path 200 includes: an electromagnetic ultrasonic receiving sensor 210, a variable filter 220, and a data acquisition module 230; wherein, the electromagnetic ultrasonic receiving sensor 210 is arranged on the outer wall of the pipeline, and the input end of the electromagnetic ultrasonic receiving sensor 210 receives the ultrasonic guided wave generated by the electromagnetic ultrasonic excitation sensor 130; the output end of the electromagnetic ultrasonic receiving sensor 210 is connected to the input end of the variable filter 220; the output end of the variable filter 220 is connected to the data acquisition module 230. Among them, the electromagnetic ultrasonic receiving sensor 210 is used to receive the ultrasonic guided wave in the pipeline and obtain the received signal of the ultrasonic guided wave and its reception time. The variable filter 220 is used to filter the received signal of the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor 210 according to a preset filtering condition; the data acquisition module 230 is used to obtain the transit time of the ultrasonic guided wave through cross-correlation calculation according to the received signal of the ultrasonic guided wave that has been filtered and its reception time, and determine the fluid velocity in the pipeline according to the transit time.

[0077] It can be seen from the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves in the above embodiments that the contact area of the guided waves excited in the device with the fluid liquid surface is larger, full circumferential measurement of the pipeline can be realized, and it is less affected by foams, bubbles, and minute impurities in the pipeline liquid, and the system has stronger robustness and anti-interference ability; and cross-correlation calculation is introduced in the calculation process of the fluid velocity, further improving the accuracy of flow velocity measurement.

[0078] Such as Figure 2As can be seen from the structural schematic diagram of another in-pipe flow velocity measurement device based on multi-frequency electromagnetic ultrasonic guided waves, in some embodiments, the in-pipe flow velocity measurement device based on multi-frequency electromagnetic ultrasonic guided waves further includes: an electromagnetic ultrasonic excitation impedance matching circuit 140 and an electromagnetic ultrasonic reception impedance matching circuit 240; among them, the electromagnetic ultrasonic excitation impedance matching circuit 140 is arranged in the electromagnetic ultrasonic excitation path 100, and the pulse excitation module 120 is connected to the electromagnetic ultrasonic excitation sensor 130 through the electromagnetic ultrasonic excitation impedance matching circuit 140. The electromagnetic ultrasonic excitation impedance matching circuit 140 is used to match the high-power pulse excitation signal according to a preset wavelength, and transmit the matched high-power pulse excitation signal to the corresponding electromagnetic ultrasonic excitation sensor 130 to provide energy for the electromagnetic ultrasonic excitation sensor 130. Through the electromagnetic ultrasonic excitation impedance matching circuit 140, the output impedance of the pulse excitation module 120 and the equivalent impedance of the electromagnetic ultrasonic excitation sensor 130 are conjugate-matched, enabling maximum power transfer between the power amplifier and the electromagnetic ultrasonic excitation sensor 130, and providing sufficient energy for the electromagnetic ultrasonic excitation process of the electromagnetic ultrasonic excitation sensor 130.

[0079] The electromagnetic ultrasonic reception impedance matching circuit 240 is arranged in the data acquisition path 200, and the electromagnetic ultrasonic reception sensor 210 is connected to the variable filter 220 through the electromagnetic ultrasonic reception impedance matching circuit 240. The electromagnetic ultrasonic reception impedance matching circuit 240 is used to perform impedance matching on the voltage signal induced by the ultrasonic guided wave received by the electromagnetic ultrasonic reception sensor 210, and transmit the matched voltage signal to the variable filter 220. Through the electromagnetic ultrasonic reception impedance matching circuit 240, the impedance between the electromagnetic ultrasonic reception sensor 210 and the subsequent data acquisition module 230 is matched; if impedance matching is not performed, serious reflections will occur, thereby damaging the instruments and equipment.

[0080] In some embodiments, the in-pipe flow velocity measurement device based on multi-frequency electromagnetic ultrasonic guided waves further includes: a power limiting module 250; the power limiting module 250 is arranged in the data acquisition path 200, and the electromagnetic ultrasonic reception impedance matching circuit 240 is connected to the variable filter 220 through the power limiting module 250. The power limiting module 250 is used to limit the voltage signal according to a preset power threshold.

[0081] In some embodiments, the in-pipe flow velocity measurement device based on multi-frequency electromagnetic ultrasonic guided waves further includes: a gain amplification module 260; the gain amplification module 260 is arranged in the data acquisition path 200, and the power limiting module 250 is connected to the variable filter 220 through the gain amplification module 260. The gain amplification module 260 is used to amplify the voltage signal according to a preset gain coefficient.

[0082] In some embodiments, the electromagnetic ultrasonic excitation sensor includes: a first electromagnetic ultrasonic sensor and a second electromagnetic ultrasonic sensor; wherein, the ultrasonic guided wave wavelengths and excitation frequencies of the first electromagnetic ultrasonic sensor and the second electromagnetic ultrasonic sensor are different; the deflection angles at which the ultrasonic guided waves of the first electromagnetic ultrasonic sensor and the second electromagnetic ultrasonic sensor are incident on the fluid are different.

[0083] In some embodiments, the electromagnetic ultrasonic excitation sensor 130 includes: a flexible coil and a soft magnet; wherein, the flexible coil group and the soft magnet group are arranged on the outer wall of the pipeline; the flexible coil and the soft magnet are arranged around the pipeline for one week; the radian of the flexible coil and the soft magnet is the same as the radian of the pipeline. The structural schematic diagram of the flexible coil is as Figure 3 shown;

[0084] Figure 2 In the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves, there are two groups of electromagnetic ultrasonic excitation sensors 130, and each group includes a flexible coil and a soft magnet; the electromagnetic ultrasonic receiving sensor 210 also includes a flexible coil and a soft magnet.

[0085] The electromagnetic ultrasonic excitation sensor 130 is connected to the electromagnetic ultrasonic excitation impedance matching circuit 140, and the electromagnetic ultrasonic receiving sensor 210 is connected to the electromagnetic ultrasonic receiving impedance matching circuit 240. The pulse excitation module 120 is a high-power pulse multi-channel excitation module, whose input end is connected to the function generator 110, and the output end is respectively connected to a plurality of electromagnetic ultrasonic excitation impedance matching circuits 140. The output end of the electromagnetic ultrasonic receiving sensor 210 is connected to the input end of the electromagnetic ultrasonic receiving impedance matching circuit 240, the output end of the electromagnetic ultrasonic receiving impedance matching circuit 240 is connected to the input end of the power limiting module 250, the output end of the power limiting module 250 is connected to the input end of the gain amplification module 260, and the output end of the gain amplification module 260 is connected to the input end of the variable filter 220; the output end of the variable filter 220 is connected to the data acquisition module 230.

[0086] In Figure 2 Based on the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves shown, as Figure 4As can be seen from the schematic diagram of energy propagation in the in-pipe flow velocity measurement device based on multi-frequency electromagnetic ultrasonic guided waves shown, a pulse signal with a certain center frequency is excited by the function generator 110. This signal is amplified by the pulse excitation module 120, and then the pulse signal is transmitted to the electromagnetic ultrasonic flexible coil in the electromagnetic ultrasonic excitation sensor 130 through the electromagnetic ultrasonic excitation impedance matching circuit 140 to generate ultrasonic guided waves in the pipeline. The ultrasonic guided waves are incident on the pipe wall at different deflection angles and continue to propagate in the liquid in the form of body waves. The excited ultrasonic waves are received by the electromagnetic ultrasonic receiving sensor 210. After the induced voltage signal of the electromagnetic ultrasonic receiving sensor 210 passes through the electromagnetic ultrasonic receiving impedance matching circuit 240, it is amplified by the power limiting module 250 and the gain amplification module 260, filtered by the variable filter 220, and finally the analog-to-digital conversion of the ultrasonic data is realized through the data acquisition module 230 for subsequent signal processing.

[0087] As can be seen from the in-pipe flow velocity measurement device based on multi-frequency electromagnetic ultrasonic guided waves in the above embodiments, the guided waves excited in this device have a larger contact area at the fluid liquid level, can achieve full circumferential measurement of the pipeline, are less affected by foams, bubbles, and minute impurities in the pipeline liquid, and the system has stronger robustness and anti-interference ability; and cross-correlation calculation is introduced in the process of calculating the fluid velocity, further improving the accuracy of flow velocity measurement.

[0088] An embodiment of the present invention provides an in-pipe flow velocity measurement method based on multi-frequency electromagnetic ultrasonic guided waves. This method is applied to the in-pipe flow velocity measurement device based on multi-frequency electromagnetic ultrasonic guided waves mentioned in the above embodiments; wherein, the in-pipe flow velocity measurement device based on multi-frequency electromagnetic ultrasonic guided waves includes: an electromagnetic ultrasonic excitation path and a data acquisition path; the electromagnetic ultrasonic excitation path includes: an electromagnetic ultrasonic excitation sensor, a pulse excitation module, and a function generator; the data acquisition path includes: an electromagnetic ultrasonic receiving sensor, a variable filter, and a data acquisition module.

[0089] The in-pipe flow velocity measurement method based on multi-frequency electromagnetic ultrasonic guided waves is as Figure 5 shown, and includes:

[0090] Step S501, controlling the function generator to generate a pulse signal according to a preset excitation frequency.

[0091] Specifically, the output end of the function generator is connected to the input end of the pulse excitation module. A pulse signal with a certain center frequency is excited by the function generator, and then the pulse signal is transmitted to the pulse excitation module.

[0092] Step S502, controlling the pulse excitation module to convert the pulse signal generated by the function generator into a high-power pulse excitation signal.

[0093] The output end of the pulse excitation module is connected to the input end of the electromagnetic ultrasonic excitation sensor. When there are multiple electromagnetic ultrasonic excitation sensors, the pulse excitation module is divided into multiple paths for transmission, and finally the converted high-power pulse excitation signals are respectively transmitted to the electromagnetic ultrasonic excitation sensors.

[0094] Step S503: Control the electromagnetic ultrasonic excitation sensor to excite the received high-power pulse excitation signal to obtain an ultrasonic guided wave, and incident the ultrasonic guided wave into the fluid in the pipeline.

[0095] The electromagnetic ultrasonic excitation sensor is arranged on the outer wall of the pipeline. The output end of the electromagnetic ultrasonic excitation sensor transmits the generated ultrasonic guided wave into the pipeline. The ultrasonic guided wave enters the pipeline liquid at different deflection angles and continues to propagate in the liquid in the form of a body wave.

[0096] Step S504: Control the electromagnetic ultrasonic receiving sensor to receive the ultrasonic guided wave in the fluid, and obtain the received signal of the ultrasonic guided wave and its receiving time.

[0097] The electromagnetic ultrasonic receiving sensor is also arranged on the outer wall of the pipeline. The input end of the electromagnetic ultrasonic receiving sensor receives the ultrasonic guided wave generated by the electromagnetic ultrasonic excitation sensor. After the excited ultrasonic wave is received by the electromagnetic ultrasonic sensor, the received signal of the ultrasonic guided wave and its receiving time are obtained, and the above data are sent to the variable filter.

[0098] Step S505: Control the variable filter to filter the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor according to the preset filtering conditions.

[0099] The output end of the electromagnetic ultrasonic receiving sensor is connected to the input end of the variable filter; the output end of the variable filter is connected to the data acquisition module. The ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor is filtered by the variable filter according to the preset filtering conditions and finally transmitted to the data acquisition module.

[0100] Step S506: Control the data acquisition module to obtain the transit time of the ultrasonic guided wave through cross-correlation calculation based on the received signal of the ultrasonic guided wave corresponding to the filtered ultrasonic guided wave and its receiving time, and determine the fluid velocity in the pipeline according to the transit time.

[0101] The data acquisition module performs relevant analog-to-digital conversion based on the received signal of the ultrasonic guided wave corresponding to the filtered ultrasonic guided wave and its receiving time, and obtains the transit time of the ultrasonic guided wave through cross-correlation calculation. Finally, the fluid velocity in the pipeline is determined according to the transit time. In an actual scenario, two sets of electromagnetic ultrasonic excitation sensors are arranged in the pipeline. These two electromagnetic ultrasonic excitation sensors excite ultrasonic guided waves with different deflection angles θ into the fluid in the pipeline. At the pipe wall-fluid interface, the guided wave is converted into a body wave and propagates in the fluid, as Figure 4As shown, when the flow velocity of the fluid in the pipeline changes, it will cause the positions where the two paths of ultrasonic waves in the fluid reach the pipe wall to change. At this time, the body wave is converted into a guided wave on the pipe wall, which in turn causes a change in the time when the receiving electromagnetic ultrasonic sensor receives the signal. The two paths can achieve computational compensation.

[0102] Thus, it can be seen that in the process of the electromagnetic ultrasonic excitation sensor exciting ultrasonic guided waves with different deflection angles θ into the fluid in the pipeline, the acquisition of the deflection angle is the enlightenment process for flow velocity measurement. In some embodiments, the step S503 of controlling the electromagnetic ultrasonic excitation sensor to excite the received high-power pulse excitation signal to obtain ultrasonic guided waves and incident the ultrasonic guided waves into the fluid in the pipeline is as Figure 6 shown, and includes:

[0103] Step S601: Control the electromagnetic ultrasonic excitation sensor to excite the high-power pulse excitation signal according to the corresponding wavelength to obtain ultrasonic guided waves including multiple phase velocities.

[0104] The process of obtaining ultrasonic guided waves is realized according to the basic theory of the vibration of ultrasonic guided waves in solids and the energy propagation of coupled vibrations on the surface of the fluid, which will not be elaborated here.

[0105] Step S602: Determine the deflection angle of the ultrasonic guided wave between the pipeline and the fluid, and control the ultrasonic guided wave to be incident into the fluid according to the deflection angle.

[0106] The deflection angle is calculated by the following formula:

[0107]

[0108] where θ is the deflection angle; c f is the longitudinal wave sound velocity in the fluid; c p is the phase velocity of the ultrasonic guided wave in the pipeline.

[0109] The ultrasonic guided wave propagates in the fluid and undergoes specular reflection when it contacts the interface between the fluid and the air, and propagates at an angle θ parallel to the wall surface. When the fluid flows at a certain speed, different flow velocities will cause the ultrasonic wave propagation path to shift and change the transit time at the same time. First, in the case of zero flow velocity, the total propagation time of the ultrasonic wave is:

[0110] t total = t pipe + t fluid ;

[0111] In the formula, t pipe is the time required for the ultrasonic wave to propagate along the path of length L in the pipeline with an inner diameter of D, and t fluid is the time for the ultrasonic wave to propagate in the fluid. The two are calculated by the following formula:

[0112]

[0113] As Figure 7 can be seen from the schematic diagram of the ultrasonic energy propagation path shown below, according to the ray tracing method, when the fluid in the pipeline has a certain flow velocity, the following formula holds:

[0114]

[0115] In the formula, is the position vector, is the flow velocity vector; is the slowness vector, defined as follows:

[0116]

[0117] In the wave propagation direction at, the unit vector perpendicular to the wavefront is It is expressed as:

[0118]

[0119] The pipe wall thickness is d. At t = 0, the path of the ultrasonic wave in the fluid starts from (x, z) = (0, d) and is expressed as:

[0120]

[0121] Substituting z = d + D into the above formula, it is obtained that the transit time of the ultrasonic wave in the fluid when the fluid is in motion is the same as that in the state of zero flow velocity, that is: The change in the position X' of the ultrasonic guided wave in the pipeline when the fluid is in motion and in the state of zero flow velocity is calculated by the following formula:

[0122]

[0123] Among them, X' is the change in the position of the ultrasonic guided wave in the pipeline when it is in motion and in the state of zero flow velocity; v is the flow velocity of the fluid.

[0124] The change in the position X' of the ultrasonic guided wave in the pipeline when the fluid is in motion and in the state of zero flow velocity causes a change in the time for the ultrasonic wave to propagate in the pipe wall. Therefore Among them, L is the propagation distance of the ultrasonic guided wave in the pipeline. Therefore, the transit time of the ultrasonic wave propagation is the sum of the propagation times of the ultrasonic guided wave in the liquid and the pipeline, and is calculated by the following formula:

[0125]

[0126] Among them, t TOF is the transit time; t fluid,vis the propagation time of the ultrasonic guided wave in a fluid with a flow velocity of v; t' pipe is the propagation time of the ultrasonic guided wave in the pipeline; D is the inner diameter length of the pipeline; L is the propagation distance of the ultrasonic guided wave in the pipeline; X' is the position change of the ultrasonic guided wave in the pipeline under the moving state and the zero-flow velocity state; C g is the group velocity of the ultrasonic guided wave in the pipeline.

[0127] In the above method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves, first, the group velocity dispersion curve is obtained according to the pipe size, wall thickness, and material density to obtain the wave structures in different modes. The dispersion curve is as Figure 8 shown. Then, the excitation frequency is selected according to the dispersion curve, wave mode, etc. The function generator generates a pulse signal of this frequency, and the pulse signal is transmitted to two electromagnetic ultrasonic excitation sensors through the pulse excitation module. Since the wavelengths of the two electromagnetic ultrasonic sensors are inconsistent, ultrasonic guided waves with different phase velocities are excited. At this time, the ultrasonic guided wave is converted into a body wave at the solid-liquid interface and enters the fluid at different deflection angles. Therefore, two propagation paths with different deflection angles will be generated in the fluid. When the flow velocity of the fluid in the pipeline changes, it will cause the deflection angles of these two transmission paths to change, and then cause the positions where the ultrasonic waves of the two paths reach the pipe wall to change, thus causing the arrival time of the received sensor signal to change. By performing envelope fitting on the received signal, the transit time of the ultrasonic wave in the pipeline can be determined, and the fluid flow velocity can be calculated. However, due to the fluctuation of the fitted envelope curve, it is easy to generate errors in the detection of the transit time. Therefore, the cross-correlation method is used to improve the detection accuracy. The cross-correlation analysis is performed on the excitation signal and the received signal of each path to obtain the transit time of each path signal. The flow velocities of the two path signals are inversely inferred through the formula, and the flow velocity values of these two path signals are weighted and averaged to finally obtain the final fluid flow velocity.

[0128] The velocity expression for the uniform flow velocity of the fluid is: v~(C f , C g , D, θ, L, t TOF ); Finally, the flow velocity v is inversely inferred. Since the wavelengths of the two excitation sensors are different, different deflection angles will be caused, and thus different propagation paths will be available. By comparing the "similarity" between the transmitted signal and the actual received signal, the termination point of the received signal is determined, as Figure 9 shown, to obtain the transit time of each signal. The flow velocities of each path are inversely inferred through the formula. Finally, the flow velocities of the two path signals are weighted and averaged to obtain the final flow velocity.

[0129] In the method for measuring the flow velocity in a pipe using multi-frequency electromagnetic ultrasonic guided waves in the above embodiments, an electromagnetic ultrasonic excitation sensor with an arc-shaped structure composed of a flexible coil and a soft magnet is used, which can be closest to the pipe surface to the greatest extent. The electromagnetic ultrasonic excitation sensor does not require a coupling agent and is in close contact with the pipe. It is applicable in both high and low temperature environments. Since the guided waves excited by electromagnetic ultrasound have a larger contact area with the liquid surface compared to other piezoelectric ultrasonic detection devices, full circumferential measurement of the pipe can be achieved, and it is less affected by foam, bubbles, and minute impurities in the pipe liquid, with stronger system robustness and anti-interference ability.

[0130] In this method, the pulse excitation module used can be a high-power multi-channel pulse excitation module, which can obtain multi-frequency electromagnetic ultrasonic signals; and it can also generate two signals with different paths excited by electromagnetic ultrasonic excitation sensors with two different wavelengths. Through the cross-correlation algorithm and the weighted average method, the accuracy of flow velocity measurement can be improved.

[0131] The method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves provided by the embodiments of the present invention has the same technical features as the device for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves provided by the above embodiments. Therefore, it can also solve the same technical problems and achieve the same technical effects. For a brief description, for the parts not mentioned in the embodiment part, reference can be made to the corresponding content in the foregoing embodiments.

[0132] This embodiment also provides an electronic device. The structural schematic diagram of the electronic device is as Figure 10 shown. The device includes a processor 101 and a memory 102; wherein, the memory 102 is used to store one or more computer instructions, and the one or more computer instructions are executed by the processor to implement the above method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves.

[0133] Figure 10 The electronic device shown also includes a bus 103 and a communication interface 104. The processor 101, the communication interface 104, and the memory 102 are connected through the bus 103.

[0134] Among them, the memory 102 may include a high-speed random access memory (RAM, Random Access Memory), and may also include a non-volatile memory, such as at least one disk memory. The bus 103 can be an ISA bus, a PCI bus, an EISA bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of simplicity of representation, Figure 10 only a bidirectional arrow is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0135] The communication interface 104 is used to connect to at least one user terminal and other network units through a network interface, and send the encapsulated IPv4 packet or IPv4 packet to the user terminal through the network interface.

[0136] The processor 101 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the integrated logic circuit in the hardware of the processor 101 or the instructions in the form of software. The above-mentioned processor 101 may be a general-purpose processor, including a central processing unit (CPU for short), a network processor (NP for short), etc.; it may also be a digital signal processor (DSP for short), an application specific integrated circuit (ASIC for short), a field programmable gate array (FPGA for short), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present disclosure. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present disclosure can be directly embodied as being executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory 102, and the processor 101 reads the information in the memory 102 and combines its hardware to complete the steps of the method in the foregoing embodiments.

[0137] The embodiments of the present invention also provide a computer-readable storage medium, on which a computer program is stored, and when the computer program is run by a processor, it executes the steps of the method in the foregoing embodiments.

[0138] In several embodiments provided by this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For another example, 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 displayed or discussed couplings or direct couplings or communication connections to each other can be through some communication interfaces. The indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0139] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0140] In addition, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0141] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a non-volatile computer-readable storage medium executable by a processor. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs and other various media that can store program codes.

[0142] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions described in the foregoing embodiments, or can easily think of changes, or make equivalent replacements for some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A device for measuring the flow velocity inside a pipe based on multi-frequency electromagnetic ultrasonic guided waves, characterized in that, The device is applied to the measurement of the fluid velocity in a pipeline. The device includes: an electromagnetic ultrasonic excitation path and a data acquisition path; The electromagnetic ultrasonic excitation path includes: an electromagnetic ultrasonic excitation sensor, a pulse excitation module, and a function generator. Wherein, the output end of the function generator is connected to the input end of the pulse excitation module; the output end of the pulse excitation module is connected to the input end of the electromagnetic ultrasonic excitation sensor; the electromagnetic ultrasonic excitation sensor is arranged on the outer wall of the pipeline, and the output end of the electromagnetic ultrasonic excitation sensor transmits the generated ultrasonic guided wave into the pipeline fluid; The data acquisition path includes: an electromagnetic ultrasonic receiving sensor, a variable filter, and a data acquisition module. Wherein, the electromagnetic ultrasonic receiving sensor is arranged on the outer wall of the pipeline, and the input end of the electromagnetic ultrasonic receiving sensor receives the ultrasonic guided wave generated by the electromagnetic ultrasonic excitation sensor; the output end of the electromagnetic ultrasonic receiving sensor is connected to the input end of the variable filter; the output end of the variable filter is connected to the data acquisition module; Wherein, the function generator is used to generate a pulse signal according to a preset excitation frequency; The pulse excitation module is used to convert the pulse signal generated by the function generator into a high-power pulse excitation signal; The electromagnetic ultrasonic excitation sensor is used to excite the ultrasonic guided wave by using the high-power pulse excitation signal generated by the pulse excitation module and incident the ultrasonic guided wave into the fluid in the pipeline; The electromagnetic ultrasonic receiving sensor is used to receive the ultrasonic guided wave in the pipeline and obtain the received signal of the ultrasonic guided wave and its reception time; The variable filter is used to filter the received signal of the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor according to a preset filtering condition; The data acquisition module is used to calculate the transit time of the ultrasonic guided wave through a cross-correlation algorithm according to the received signal of the ultrasonic guided wave that has been filtered and its reception time, and determine the fluid velocity in the pipeline according to the transit time.

2. The in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves according to claim 1, characterized in that The device further includes: an electromagnetic ultrasonic excitation impedance matching circuit and an electromagnetic ultrasonic receiving impedance matching circuit; Wherein, the electromagnetic ultrasonic excitation impedance matching circuit is arranged in the electromagnetic ultrasonic excitation path, and the pulse excitation module is connected to the electromagnetic ultrasonic excitation sensor through the electromagnetic ultrasonic excitation impedance matching circuit; the electromagnetic ultrasonic receiving impedance matching circuit is arranged in the data acquisition path, and the electromagnetic ultrasonic receiving sensor is connected to the variable filter through the electromagnetic ultrasonic receiving impedance matching circuit; The electromagnetic ultrasonic excitation impedance matching circuit is used to perform conjugate matching on the high-power pulse excitation signal according to a preset wavelength and transmit the high-power pulse excitation signal after the matching is completed to the corresponding electromagnetic ultrasonic excitation sensor to provide energy for the electromagnetic ultrasonic excitation sensor; The electromagnetic ultrasonic receiving impedance matching circuit is used to perform impedance matching on the voltage signal induced by the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor, and transmit the voltage signal after the matching is completed to the variable filter.

3. The in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves according to claim 2, wherein The device further includes: a power limiting module; The power limiting module is arranged in the data acquisition path, and the electromagnetic ultrasonic excitation impedance matching circuit is connected to the variable filter through the power limiting module; The power limiting module is used to limit the voltage signal according to a preset power threshold.

4. The in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves according to claim 3, wherein The device further includes: a gain amplification module; The gain amplification module is arranged in the data acquisition path, and the power limiting module is connected to the variable filter through the gain amplification module; The gain amplification module is used to perform gain amplification on the voltage signal according to a preset gain coefficient.

5. The in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves according to claim 1, wherein, The electromagnetic ultrasonic excitation sensor includes: a first electromagnetic ultrasonic sensor and a second electromagnetic ultrasonic sensor; Wherein, the ultrasonic guided wave wavelengths and excitation frequencies of the first electromagnetic ultrasonic sensor and the second electromagnetic ultrasonic sensor are different; The deflection angles at which the ultrasonic guided waves generated by the first electromagnetic ultrasonic sensor and the second electromagnetic ultrasonic sensor are incident on the fluid are different.

6. The in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves according to claim 5, wherein The electromagnetic ultrasonic excitation sensor includes: a flexible coil and a soft magnet; Wherein, the flexible coil and the soft magnet are arranged on the outer wall of the pipeline; the flexible coil and the soft magnet are arranged around the pipeline for one week; the radian of the flexible coil is the same as the radian of the pipeline.

7. A method for measuring the flow velocity inside a pipe based on multi-frequency electromagnetic ultrasonic guided waves, characterized in that, The method is applied to the in-pipe flow velocity measuring device based on multi-frequency electromagnetic ultrasonic guided waves according to any one of claims 1 to 6 above; wherein, the device includes: an electromagnetic ultrasonic excitation path and a data acquisition path; the electromagnetic ultrasonic excitation path includes: an electromagnetic ultrasonic excitation sensor, a pulse excitation module and a function generator; the data acquisition path includes: an electromagnetic ultrasonic receiving sensor, a variable filter and a data acquisition module; The method includes: Controlling the function generator to generate a pulse signal according to a preset excitation frequency; Controlling the pulse excitation module to convert the pulse signal generated by the function generator into a high-power pulse excitation signal; Controlling the electromagnetic ultrasonic excitation sensor to excite the received high-power pulse excitation signal to obtain the ultrasonic guided wave, and incident the ultrasonic guided wave into the fluid in the pipeline; Controlling the electromagnetic ultrasonic receiving sensor to receive the ultrasonic guided wave in the fluid, and obtaining the received signal of the ultrasonic guided wave and its reception time; Controlling the variable filter to filter the ultrasonic guided wave received by the electromagnetic ultrasonic receiving sensor according to a preset filtering condition; Controlling the data acquisition module to obtain the transit time of the ultrasonic guided wave through cross-correlation calculation according to the received signal corresponding to the ultrasonic guided wave after the filtering is completed and its reception time, and determine the fluid velocity in the pipeline according to the transit time.

8. The method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves according to claim 7, characterized in that, The step of controlling the electromagnetic ultrasonic excitation sensor to excite the received high-power pulse excitation signal to obtain the ultrasonic guided wave and incident the ultrasonic guided wave into the fluid in the pipeline includes: Controlling the electromagnetic ultrasonic excitation sensor to excite the high-power pulse excitation signal according to the corresponding wavelength to obtain the ultrasonic guided wave including multiple phase velocities; Determining the deflection angle between the ultrasonic guided wave in the pipeline and the fluid, and controlling the ultrasonic guided wave to be incident into the fluid according to the deflection angle; wherein, the deflection angle is calculated by the following formula: ； Wherein, is the deflection angle; is the longitudinal wave sound velocity in the fluid; is the phase velocity of the ultrasonic guided wave in the pipeline.

9. The method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves according to claim 8, characterized in that, Calculating the transit time of the ultrasonic guided wave, which is calculated by the following formula: ； Wherein, is the transit time; is the propagation time of the ultrasonic guided wave in the fluid when the flow velocity is ; is the propagation time of the ultrasonic guided wave in the pipeline; is the inner diameter length of the pipeline; is the propagation distance of the ultrasonic guided wave in the pipeline; is the position change amount of the ultrasonic guided wave in the pipeline when in the moving state and in the state without fluid movement; is the group velocity of the ultrasonic guided wave in the pipeline.

10. The method for measuring the flow velocity in a pipe based on multi-frequency electromagnetic ultrasonic guided waves according to claim 9, characterized in that, The position change amount in the pipeline when the ultrasonic guided wave is in the moving state and when there is no fluid movement state is calculated by the following formula: ； wherein, is the amount of change in the position of the ultrasonic guided wave in the pipeline under the moving state and the state without fluid movement; is the flow velocity of the fluid.

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