Method for detecting gas content of gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves

Abstract

The invention discloses a method for detecting the gas content of a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves. The method comprises the following steps: arranging an ultrasonic transducer array along the circumferential direction of the gas-liquid two-phase flow pipeline to be detected; ultrasonic guided waves are emitted through an ultrasonic transducer array, and ultrasonic guided wave displacement signals are received; performing differential processing on the received ultrasonic guided wave displacement signal to obtain a differential displacement signal; constructing and training a cross section gas-containing rate prediction model to obtain a trained cross section gas-containing rate prediction model, and inputting the differential displacement signal into the trained cross section gas-containing rate prediction model to obtain the gas-containing rate of the to-be-detected gas-liquid two-phase flow pipeline. The method is suitable for detecting the gas content of gas-liquid two-phase flow pipelines with different pipe diameters, different flow speeds and different flow patterns, has good universality and practicability, provides an efficient solution for nondestructive detection of the gas content of the gas-liquid two-phase flow in the industry, and is worthy of popularization.

Description

Technical Field

[0001] The invention relates to the technical field of gas content detection, and in particular to a method for detecting the gas content of a gas-liquid two-phase flow pipeline. Background Art

[0002] The gas content in the gas-liquid two-phase flow in the pipeline is one of the important parameters in the field of industrial production. Accurately measuring the gas content in the gas-liquid two-phase flow in the pipeline is of great significance for the rational optimization of the production control system and the formulation and adjustment of industrial production strategies. However, the existing gas-liquid gas content detection methods have certain limitations. The most significant problem is that it is difficult to achieve high-precision detection of the gas content in the gas-liquid two-phase flow without destroying the pipeline structure. In view of this problem, ultrasonic nondestructive testing technology provides a feasible and effective solution. For example, the invention patent with application number 201510244409.2 discloses a method for measuring the gas content of two-phase flow based on ultrasonic dual-frequency signals. The method includes the following steps: an ultrasonic transmitting probe and an ultrasonic receiving probe are respectively set at both ends of a straight pipe where the gas content of two-phase flow needs to be measured; two ultrasonic signals with excitation frequencies of the first excitation frequency and the second excitation frequency propagating along the fluid in the straight pipe are generated by the ultrasonic transmitting probe; the characteristic parameters of the two ultrasonic signals received are detected by the ultrasonic receiving probe; the gas content is calculated according to the first excitation frequency, the second excitation frequency, the propagation speed of pure liquid, the resonant frequency of bubbles in the two-phase flow, the vibration damping of bubbles and the characteristic parameters of the two ultrasonic signals. Non-contact measurement of the gas content of two-phase flow is achieved.

[0003] The above patents and mainstream ultrasonic nondestructive testing technologies are mostly based on the principle of body wave reflection method. Traditional body wave testing obtains gas content information by studying the acoustic characteristics of the medium in which ultrasonic waves are transmitted inside the pipeline. Therefore, it is greatly affected by the transmission medium inside the pipeline, especially in high-viscosity fluids such as crude oil, asphalt, and tar. The attenuation of body waves is high, resulting in unsatisfactory test results. Ultrasonic guided waves have unique propagation characteristics. They propagate directly along the pipeline and are less affected by the medium in the pipeline. In addition, they fully interact with the gas-liquid two-phase medium in the pipeline during propagation, and can reflect the characteristics of the fluid in the entire cross section. Summary of the invention

[0004] The present invention proposes a method for detecting the gas content of a two-phase flow in a pipeline by circumferential ultrasonic guided waves, so as to solve the problem that the existing gas content detection methods are difficult to detect the gas content of a gas-liquid two-phase flow pipeline with high precision and low cost without destroying the pipeline structure, thereby reducing the risk of production accidents and improving energy utilization efficiency.

[0005] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves comprises the following steps:

[0007] Arrange an ultrasonic transducer array along the circumference of the gas-liquid two-phase flow pipeline to be tested; transmit ultrasonic guided waves through the ultrasonic transducer array and receive ultrasonic guided wave displacement signals;

[0008] Performing differential processing on the received ultrasonic guided wave displacement signal to obtain a differential displacement signal;

[0009] A cross-sectional gas content prediction model is constructed and trained to obtain a trained cross-sectional gas content prediction model, and the differential displacement signal is input into the trained cross-sectional gas content prediction model to obtain the gas content of the gas-liquid two-phase flow pipeline to be tested.

[0010] Preferably, one or more groups of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be tested; the ultrasonic transducer array includes two pairs of ultrasonic transducers; the two pairs of ultrasonic transducers include a first transmitting ultrasonic transducer, a first receiving ultrasonic transducer and a second transmitting ultrasonic transducer, a second receiving ultrasonic transducer.

[0011] Preferably, when a group of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be tested: the first transmitting ultrasonic transducer, the first receiving ultrasonic transducer, the second transmitting ultrasonic transducer and the second receiving ultrasonic transducer are arranged at equal intervals along the circumference of the gas-liquid two-phase flow pipeline to be tested, and the first transmitting ultrasonic transducer, the first receiving ultrasonic transducer, the second transmitting ultrasonic transducer and the second receiving ultrasonic transducer are on the same radial section of the gas-liquid two-phase flow pipeline to be tested.

[0012] Preferably, when a group of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be measured, the method of transmitting ultrasonic guided waves and receiving ultrasonic guided wave displacement signals through the ultrasonic transducer array is: the first transmitting ultrasonic transducer and the second transmitting ultrasonic transducer are excited at the same angle and in an oblique incidence manner at the same time, the first transmitting ultrasonic transducer emits a first ultrasonic guided wave, the second transmitting ultrasonic transducer emits a second ultrasonic guided wave, the first ultrasonic guided wave and the second ultrasonic guided wave enter the gas-liquid two-phase flow pipeline to be measured and propagate circumferentially, the first ultrasonic guided wave displacement signal is received by the first receiving ultrasonic transducer, and the second ultrasonic guided wave displacement signal is received by the second receiving ultrasonic transducer;

[0013] The method for obtaining the differential displacement signal is: performing differential processing on the first ultrasonic guided wave displacement signal and the second ultrasonic guided wave displacement signal to obtain the differential displacement signal.

[0014] Preferably, the method for constructing a cross-sectional gas content prediction model is:

[0015] Combined with the boundary conditions, the motion equations of ultrasonic guided waves are derived, proving that there is a corresponding relationship between the differential displacement signal and the gas fraction.

[0016] Through the simulation software, the flow pattern and gas content combination configuration in the gas-liquid two-phase flow pipeline are dynamically adjusted to obtain the differential displacement signals corresponding to different gas contents under different flow patterns. A training data set containing multiple sets of flow pattern-gas content-differential displacement signal correspondences is generated. The training data set is input into the deep learning model for training, so that the deep learning model can learn the mapping relationship between gas content and differential displacement signal, and obtain the cross-sectional gas content prediction model.

[0017] Preferably, the deep learning model is selected from an LSTM network, a Transformer network or an LSTM-Transformer model.

[0018] Preferably, the method for deriving the group of motion equations of ultrasonic guided waves in combination with boundary conditions is: combining the wave equation of ultrasonic guided waves propagating under solids with the ordinary differential equation of the wave equation of ultrasonic guided waves in the fluid domain and the boundary conditions of fluid-solid coupling to obtain the group of motion equations of ultrasonic guided waves.

[0019] Preferably, the motion equations of the ultrasonic guided wave are:

[0020]

[0021]

[0022]

[0023] Among them, ρ s represents the density of the solid, ρ f represents the density of the fluid; i is an imaginary unit, r1 is the outer diameter of the pipe; λ s and μ s is the Lamé constant of the solid material, μ f is the dynamic viscosity of the fluid; and Respectively represent the displacement components in the radial, circumferential and axial directions in the solid; V fr 、V fθ and V fz Respectively represent the velocity components in the radial, circumferential and axial directions of the fluid; k θ , k z are the circumferential and axial components of the wave number respectively; Ω is the angular frequency, P f Indicates the pressure in the fluid.

[0024] Preferably, when multiple groups of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be tested, assuming that the number of groups is N, N>1, then each receiving ultrasonic transducer receives an ultrasonic guided wave displacement signal consisting of 2N ultrasonic guided waves. When the receiving ultrasonic transducer receives the ultrasonic guided wave emitted by the transmitting ultrasonic transducer with the shortest distance from the receiving ultrasonic transducer on the path of circumferential ultrasonic guided wave propagation, the receiving is terminated, and the two ultrasonic guided wave displacement signals obtained by each group of ultrasonic transducer arrays are differentially processed to obtain N differential displacement signals. The N differential displacement signals are input into the corresponding trained cross-section gas content prediction model to obtain the gas content of the gas-liquid two-phase flow pipeline to be tested.

[0025] Preferably, the ultrasonic transducer array further includes four mechanical fixing bases; the first transmitting ultrasonic transducer, the first receiving ultrasonic transducer, the second transmitting ultrasonic transducer and the second receiving ultrasonic transducer are all fixed on the gas-liquid two-phase flow pipeline to be measured through the mechanical fixing bases.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides an innovative method for detecting the gas content of gas-liquid two-phase flow pipelines. By making full use of the propagation characteristics of ultrasonic guided waves, the detection accuracy of the gas content of gas-liquid two-phase flow in industry is improved. The present invention is suitable for detecting the gas content of gas-liquid two-phase flow pipelines with different pipe diameters, different flow rates, and different flow types. It has good versatility and practicality, and provides an efficient solution for non-destructive detection of the gas content of gas-liquid two-phase flow in industry, which is worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a flow chart of the present invention.

[0030] Figure 2 It is a front view of the cross section of a gas-liquid two-phase flow pipeline to be tested in one embodiment of the present invention.

[0031] Figure 3 It is an overall three-dimensional diagram of the gas-liquid two-phase flow pipeline to be tested in one embodiment of the present invention.

[0032] Figure 4 FIG. 4 is a differential signal displacement diagram in an embodiment of the present invention.

[0033] Figure 5Schematic diagram of a simulation model for a 21% gas content fraction in one embodiment of the present invention.

[0034] Figure 6 This is a diagram of ultrasonic guided wave displacement signals received by two receiving transducers during a simulation of a gas content of 21% in one embodiment of the present invention.

[0035] Figure 7 This is a differential displacement signal diagram during simulation of a gas content of 21% in one embodiment of the present invention.

[0036] Figure 8 1 is a differential displacement signal diagram during simulation of different gas content fractions in one embodiment of the present invention.

[0037] Fig. 9 This is a relative error diagram of the gas content predicted under stratified flow according to the present invention. In the figure, the abscissa is the sample number of different gas content.

[0038] In the figure, 1-first transmitting ultrasonic transducer, 2-first receiving ultrasonic transducer, 3-second transmitting ultrasonic transducer, 4-second receiving ultrasonic transducer, 5-mechanical fixing base. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] like Figure 1 As shown, a method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves comprises the following steps:

[0041] Arrange an ultrasonic transducer array along the circumference of the gas-liquid two-phase flow pipeline to be tested; transmit ultrasonic guided waves through the ultrasonic transducer array and receive ultrasonic guided wave displacement signals;

[0042] Performing differential processing on the received ultrasonic guided wave displacement signal to obtain a differential displacement signal;

[0043] A cross-sectional gas content prediction model is constructed and trained to obtain a trained cross-sectional gas content prediction model, and the differential displacement signal is input into the trained cross-sectional gas content prediction model to obtain the gas content of the gas-liquid two-phase flow pipeline to be tested.

[0044] Furthermore, one or more groups of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be tested; the ultrasonic transducer array includes two pairs of ultrasonic transducers; the two pairs of ultrasonic transducers include a first transmitting ultrasonic transducer 1, a first receiving ultrasonic transducer 2 and a second transmitting ultrasonic transducer 3, and a second receiving ultrasonic transducer 4.

[0045] Specifically, Figure 2 and Figure 3 As shown, when a group of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be tested: the first transmitting ultrasonic transducer 1, the first receiving ultrasonic transducer 2, the second transmitting ultrasonic transducer 3 and the second receiving ultrasonic transducer 4 are arranged at equal intervals along the circumference of the gas-liquid two-phase flow pipeline to be tested, and the first transmitting ultrasonic transducer 1, the first receiving ultrasonic transducer 2, the second transmitting ultrasonic transducer 3 and the second receiving ultrasonic transducer 4 are on the same radial section of the gas-liquid two-phase flow pipeline to be tested.

[0046] Specifically, the ultrasonic transducer array also includes four mechanical fixing bases 5; the first transmitting ultrasonic transducer 1, the first receiving ultrasonic transducer 2, the second transmitting ultrasonic transducer 3, and the second receiving ultrasonic transducer 4 are all fixed on the gas-liquid two-phase flow pipeline to be measured through the mechanical fixing base 5.

[0047] The first transmitting ultrasonic transducer 1 and the second transmitting ultrasonic transducer 3 are excited at the same angle and in an oblique incidence manner. The first transmitting ultrasonic transducer 1 emits a first ultrasonic guided wave, and the second transmitting ultrasonic transducer 3 emits a second ultrasonic guided wave. The first ultrasonic guided wave and the second ultrasonic guided wave enter the gas-liquid two-phase flow pipeline to be measured and propagate circumferentially. The first ultrasonic guided wave displacement signal is received by the first receiving ultrasonic transducer 2, and the second ultrasonic guided wave displacement signal is received by the second receiving ultrasonic transducer 4.

[0048] The same angle means that the angle between the first ultrasonic guided wave emitted by the first transmitting ultrasonic transducer 1 and the pipe wall is the same as the angle between the second ultrasonic guided wave emitted by the second transmitting ultrasonic transducer 3 and the pipe wall.

[0049] The first ultrasonic guided wave displacement signal and the second ultrasonic guided wave displacement signal are differentially processed to obtain a differential displacement signal.

[0050] Specifically, the first transmitting ultrasonic transducer 1 and the second transmitting ultrasonic transducer 3 simultaneously emit the first ultrasonic guided wave and the second ultrasonic guided wave respectively, and the first ultrasonic guided wave and the second ultrasonic guided wave propagate circumferentially in the gas-liquid two-phase flow pipeline to be measured. While the first receiving ultrasonic transducer 2 receives the first ultrasonic guided wave, the second receiving ultrasonic transducer 4 receives the second ultrasonic guided wave. As time changes, the first receiving ultrasonic transducer 2 receives the second ultrasonic guided wave, and the second receiving ultrasonic transducer 4 receives the first ultrasonic guided wave. Since the transmission medium in the gas-liquid two-phase flow pipeline to be measured changes its acoustic characteristics when the ultrasonic guided wave propagates, the first ultrasonic guided wave received by the second receiving ultrasonic transducer 4 is different from the first ultrasonic guided wave received by the first receiving ultrasonic transducer 2. Similarly, the second ultrasonic guided wave received by the first receiving ultrasonic transducer 2 is also different from the second ultrasonic guided wave received by the second receiving ultrasonic transducer 4. The first receiving ultrasonic transducer 2 regards the received signal (including the first and second ultrasonic guided waves) as a first ultrasonic guided wave displacement signal, and similarly, the second receiving ultrasonic transducer 4 regards the received signal (including the first and second ultrasonic guided waves) as a second ultrasonic guided wave displacement signal;

[0051] By performing differential processing on the obtained first ultrasonic guided wave displacement signal and the second ultrasonic guided wave displacement signal, a differential displacement signal carrying information between the gas / liquid interface of the entire pipeline section can be obtained.

[0052] Furthermore, if you need to improve the accuracy, Figure 4 As shown, multiple groups of ultrasonic transducer arrays can be arranged on the gas-liquid two-phase flow pipeline to be tested. When multiple groups of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be tested, assuming that the number of groups is N, N>1, then each receiving ultrasonic transducer receives an ultrasonic guided wave displacement signal composed of 2N ultrasonic guided waves. When the receiving ultrasonic transducer receives the ultrasonic guided wave emitted by the transmitting ultrasonic transducer with the shortest distance from the receiving ultrasonic transducer on the path of circumferential ultrasonic guided wave propagation, the receiving is terminated, and the two ultrasonic guided wave displacement signals obtained by each group of ultrasonic transducer arrays are differentially processed to obtain N differential displacement signals, and the N differential displacement signals are input into the corresponding trained cross-section gas content prediction model to obtain the gas content of the gas-liquid two-phase flow pipeline to be tested.

[0053] Furthermore, the method for constructing the cross-sectional gas content prediction model is:

[0054] Combined with the boundary conditions, the motion equations of ultrasonic guided waves are derived, proving that there is a corresponding relationship between the differential displacement signal and the gas fraction.

[0055] Specifically, the following is the wave equation for ultrasonic guided waves propagating in solids. Since the wave equation for ultrasonic guided waves propagating in solids has different solutions under different boundary conditions;

[0056]

[0057] Where ρ is the medium density, λ is the Lame constant, and u z ,u θ ,u r The displacement functions are axial, circumferential and radial respectively. is the volume strain, r is the radius of the pipe cross section, t is the time, and μ is the displacement.

[0058] When the boundary condition is a fluid-solid coupling boundary condition, the wave equation of ultrasonic guided waves propagating under solid is combined with the ordinary differential equation of the wave equation of ultrasonic guided waves in the fluid domain and the boundary condition of fluid-solid coupling to obtain the motion equations of ultrasonic guided waves:

[0059]

[0060]

[0061] ρ s represents the density of the solid (pipe material), ρ f Represents the density of the fluid; they are used to reflect the mass characteristics of the material in the wave equation and have an impact on the wave propagation speed, etc. i is an imaginary unit and r1 is the outer diameter of the pipe.

[0062] λ s and μ s is the Lame constant of solid materials, used to describe the elastic properties of solids; μ f It is the dynamic viscosity of the fluid, reflecting the characteristics of the fluid that hinder relative flow.

[0063] and They represent the radial, circumferential and axial displacement components in the solid, respectively, and are used to describe the deformation of the solid medium under the action of ultrasonic guided waves.

[0064] V fr 、V fθ and V fz They represent the radial, circumferential and axial velocity components in the fluid respectively, reflecting the motion state of the fluid under the influence of ultrasonic guided waves.

[0065] k θ , k z are the circumferential and axial components of the wave number respectively. The wave number is related to the wavelength and reflects the spatial periodicity of the wave in different directions.

[0066] ω is the angular frequency, which is used to describe how fast a wave vibrates and is related to the frequency of the wave.

[0067] P f Represents the pressure in the fluid. In the wave equation of fluid-solid interaction, pressure has an important influence on the interaction between fluid and solid.

[0068] When the gas content and flow pattern of the fluid are known, the density of the fluid ρ f and the dynamic viscosity μ of the fluid f The displacement signal of ultrasonic guided waves in the circumferential propagation of the pipeline is obtained by solving the above motion equations by finite element or finite difference methods. f and the dynamic viscosity μ of the fluid f It will change with the change of gas content and flow pattern of gas-liquid two-phase flow in the pipeline, so that the displacement signal of ultrasonic guided wave in the circumferential propagation motion of the pipeline will also change accordingly. Therefore, different boundary conditions will cause different displacement signals of ultrasonic guided waves when ultrasonic guided waves propagate circumferentially in the pipeline.

[0069] Theoretical analysis based on the above-mentioned ultrasonic guided wave gas content detection mechanism in the gas-liquid two-phase flow pipeline. Dynamically adjust the flow pattern and gas content combination configuration in the gas-liquid two-phase flow pipeline through simulation software or a professional two-phase flow pipeline system, obtain the differential displacement signal corresponding to different gas contents under different flow patterns, generate a training data set containing multiple sets of flow pattern-gas content-differential displacement signal correspondences, input the training data set into the deep learning model for training, so that the deep learning model learns the mapping relationship between gas content and differential displacement signal, and obtains the cross-sectional gas content prediction model. The deep learning model is selected from LSTM (Long Short-Term Memory) network, Transformer network or LSTM-Transformer model.

[0070] In order to verify the effectiveness of the present invention, the finite element method was used to conduct a preliminary theoretical analysis on the gas content detection mechanism of ultrasonic guided waves in gas-liquid two-phase flow pipelines, and a theoretical simulation model for ultrasonic guided wave detection of gas content was established. The parameters were set as follows: the gas-liquid two-phase flow pipeline structure material is steel, the elastic modulus is 200GPa, the Poisson's ratio is 0.35, and the density is 7850kg / m3. The outer diameter of the pipeline structure is 32mm, the inner diameter is 28.5mm, and the wall thickness is 1.75mm.

[0071] like Figure 5 As shown, the upper and lower transmitting ultrasonic transducers respectively transmit transmitting signal 1 and transmitting signal 2 at the same time at a 45° oblique incidence. When the receiving ultrasonic transducer on the right receives transmitting signal 1, the receiving ultrasonic transducer on the left receives transmitting signal 2. At this time, receiving signal 2 contains part of the liquid interface information and half of the gas information, and receiving signal 1 contains all liquid information. At this time, if receiving signal 2 and receiving signal 1 are differentiated, half of the gas interface information can be obtained.

[0072] As time changes, the receiving ultrasonic transducer on the left can receive the transmitting signal 1 whose propagation path is 3 / 4 of a circle and contains all the gas interface information and most of the liquid information. The receiving ultrasonic transducer on the right can receive the transmitting signal 2 whose source is different from the receiving ultrasonic transducer on the left and is the transmitting ultrasonic transducer below. Due to the different boundary conditions on the propagation path, there will be obvious differences. The final receiving signal 1 and the receiving signal 2 are different. This difference is reflected by Figure 6 It can be clearly seen that by performing differential processing on the final received signal 1 and the received signal 2, a differential displacement signal carrying information about the gas / liquid interface of the entire pipeline section can be obtained. The differential displacement signal is as follows: Figure 7 As shown. After differential processing of the ultrasonic guided wave displacement signal collected by the receiving super energy transducer, it is a set of discrete time signals, and the LSTM network can effectively capture the long-term dependencies in the sequence data, which is very useful for processing sequence data such as ultrasonic guided wave signals with time sequence. It can remember the important information of the earlier moments in the sequence and use this information in subsequent processing. The Transformer network can process sequence data in parallel, and can capture the dependencies between any positions in the sequence through the self-attention mechanism, without being restricted by the length of the sequence. It has higher efficiency and better performance when processing long sequences. Therefore, the LSTM-Transformer model is used to extract features and train and fit the model for the collected differential displacement signals and the corresponding two-phase flow pattern and gas content parameters.

[0073] The differential displacement signals under different flow patterns and gas content are different. Figure 8 is the differential displacement signal under different gas content. The differential displacement signal of each gas content is input into the cross-sectional gas content prediction model. The cross-sectional gas content prediction model predicts the gas content according to the known two-phase flow pattern and the detected differential displacement signal, such as Fig. 9 As shown in the relative error graph of the present invention for predicting gas content under stratified flow, the relative errors of all prediction samples are less than 5%, and the relative errors of most prediction samples are less than 1%, which verifies the effectiveness and high accuracy of the present invention.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves, characterized in that: The following steps are involved: Arrange an ultrasonic transducer array along the circumference of the gas-liquid two-phase flow pipeline to be tested; transmit ultrasonic guided waves through the ultrasonic transducer array and receive ultrasonic guided wave displacement signals; Performing differential processing on the received ultrasonic guided wave displacement signal to obtain a differential displacement signal; A cross-sectional gas content prediction model is constructed and trained to obtain a trained cross-sectional gas content prediction model, and the differential displacement signal is input into the trained cross-sectional gas content prediction model to obtain the gas content of the gas-liquid two-phase flow pipeline to be tested.

2. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to claim 1 is characterized in that: One or more groups of ultrasonic transducer arrays are arranged on a gas-liquid two-phase flow pipeline to be tested; the ultrasonic transducer array comprises two pairs of ultrasonic transducers; the two pairs of ultrasonic transducers comprise a first transmitting ultrasonic transducer (1), a first receiving ultrasonic transducer (2) and a second transmitting ultrasonic transducer (3), a second receiving ultrasonic transducer (4).

3. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to claim 2 is characterized in that: When a group of ultrasonic transducer arrays are arranged on a gas-liquid two-phase flow pipeline to be tested: a first transmitting ultrasonic transducer (1), a first receiving ultrasonic transducer (2), a second transmitting ultrasonic transducer (3) and a second receiving ultrasonic transducer (4) are arranged at equal intervals along the circumference of the gas-liquid two-phase flow pipeline to be tested, and the first transmitting ultrasonic transducer (1), the first receiving ultrasonic transducer (2), the second transmitting ultrasonic transducer (3) and the second receiving ultrasonic transducer (4) are on the same radial section of the gas-liquid two-phase flow pipeline to be tested.

4. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to claim 3 is characterized in that: When a group of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be measured, the method for transmitting ultrasonic guided waves and receiving ultrasonic guided wave displacement signals through the ultrasonic transducer array is as follows: the first transmitting ultrasonic transducer (1) and the second transmitting ultrasonic transducer (3) are excited at the same angle and in an oblique incidence manner at the same time, the first transmitting ultrasonic transducer (1) emits a first ultrasonic guided wave, the second transmitting ultrasonic transducer (3) emits a second ultrasonic guided wave, the first ultrasonic guided wave and the second ultrasonic guided wave enter the gas-liquid two-phase flow pipeline to be measured and propagate circumferentially, the first ultrasonic guided wave displacement signal is received by the first receiving ultrasonic transducer (2), and the second ultrasonic guided wave displacement signal is received by the second receiving ultrasonic transducer (4); The method for obtaining the differential displacement signal is: performing differential processing on the first ultrasonic guided wave displacement signal and the second ultrasonic guided wave displacement signal to obtain the differential displacement signal.

5. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to claim 1, characterized in that: The method for constructing the cross-section gas content prediction model is: Combined with the boundary conditions, the motion equations of ultrasonic guided waves are derived, proving that there is a corresponding relationship between the differential displacement signal and the gas fraction. Through the simulation software, the flow pattern and gas content combination configuration in the gas-liquid two-phase flow pipeline are dynamically adjusted to obtain the differential displacement signals corresponding to different gas contents under different flow patterns. A training data set containing multiple sets of flow pattern-gas content-differential displacement signal correspondences is generated. The training data set is input into the deep learning model for training, so that the deep learning model can learn the mapping relationship between gas content and differential displacement signal, and obtain the cross-sectional gas content prediction model.

6. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to claim 5 is characterized in that: The deep learning model is selected from an LSTM network, a Transformer network or an LSTM-Transformer model.

7. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to claim 5 or 6, characterized in that: The method for deriving the motion equations of ultrasonic guided waves in combination with boundary conditions is as follows: combining the wave equations of ultrasonic guided waves propagating under solids with the ordinary differential equations of the wave equations of ultrasonic guided waves in a fluid domain and the boundary conditions of fluid-solid coupling to obtain the motion equations of ultrasonic guided waves.

8. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to claim 7, characterized in that: The motion equations of the ultrasonic guided wave are: Among them, ρ s represents the density of the solid, ρ f represents the density of the fluid; i is an imaginary unit, r1 is the outer diameter of the pipe; λ s and μ s is the Lamé constant of the solid material, μ f is the dynamic viscosity of the fluid; and Respectively represent the displacement components in the radial, circumferential and axial directions in the solid; V fr 、V fθ and V fz Respectively represent the velocity components in the radial, circumferential and axial directions of the fluid; k θ , k z are the circumferential and axial components of the wave number respectively; Ω is the angular frequency, P f Indicates the pressure in the fluid.

9. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to claim 2, characterized in that: When multiple groups of ultrasonic transducer arrays are arranged on the gas-liquid two-phase flow pipeline to be tested, assuming that the number of groups is N, N>1, then the ultrasonic guided wave displacement signal received by each receiving ultrasonic transducer consists of 2N ultrasonic guided waves. When the receiving ultrasonic transducer receives the ultrasonic guided wave emitted by the transmitting ultrasonic transducer with the shortest distance from the receiving ultrasonic transducer on the path of circumferential ultrasonic guided wave propagation, the receiving is terminated, and the two ultrasonic guided wave displacement signals obtained by each group of ultrasonic transducer arrays are differentially processed to obtain N differential displacement signals. The N differential displacement signals are input into the corresponding trained cross-section gas content prediction model to obtain the gas content of the gas-liquid two-phase flow pipeline to be tested.

10. The method for detecting gas content in a gas-liquid two-phase flow pipeline based on circumferential ultrasonic guided waves according to any one of claims 1 to 3 or 9, characterized in that: The ultrasonic transducer array further comprises four mechanical fixing bases (5); the first transmitting ultrasonic transducer (1), the first receiving ultrasonic transducer (2), the second transmitting ultrasonic transducer (3) and the second receiving ultrasonic transducer (4) are all fixed on the gas-liquid two-phase flow pipeline to be measured via the mechanical fixing bases (5).

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