Pipeline defect detection method and detection system

Abstract

The invention discloses a pipeline defect detection method and system, and the method comprises the steps: employing a bubble spraying device to spray bubbles in a pipeline, so as to enable the bubbles to be attached to the inner wall of the pipeline; an ultrasonic signal acquisition device is adopted to emit ultrasonic waves to the pipeline, and echo signals are enhanced in a bubble resonance mode; filtering the received echo signal to eliminate the influence of the high-frequency noise signal; performing fast Fourier transform on the echo signal to obtain a frequency spectrum of the echo signal; picking up the position of the maximum peak value of the frequency spectrum to obtain a formant sequence; and obtaining a formant abnormal value in the formant sequence, and judging whether the pipeline has defects or not according to the formant abnormal value. A broadband excitation signal is adopted to excite an air bubble film on the surface of the inner wall of the pipeline, filtering processing and fast Fourier transform are carried out on an echo signal, a formant abnormal value in a formant sequence is obtained, whether the pipeline has defects or not is judged according to the formant abnormal value, and therefore the slight defects of the pipeline are recognized, and the defect recognition rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline detection, and particularly to a pipeline defect detection method and a detection system. Background Art

[0002] Ultrasonic testing is a commonly used non-destructive testing method for pipelines, which is widely applied to scenarios such as pipeline wall thickness measurement, corrosion assessment, and defect identification. The traditional ultrasonic pulse-echo method relies on ultrasonic waves penetrating the pipeline to be measured, and calculates the pipeline thickness and identifies internal defects through the echo time. However, this method has great limitations in detecting minor defects such as micro-cracks. The propagation path of ultrasonic waves is prone to scattering or attenuation, resulting in difficult signal recognition and decreased sensitivity. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a pipeline defect detection method and a detection system, which use a broadband excitation signal to excite the bubble film on the inner wall surface of the pipeline, induce non-linear resonance or spectral distortion, analyze and process the echo signal, realize the identification of minor pipeline defects, and improve the defect identification rate.

[0004] An embodiment of the present invention provides a pipeline defect detection method based on a pipeline defect detection system. The detection system includes a bubble spraying device and an ultrasonic signal acquisition device. The detection method includes: Spray bubbles in the pipeline using the bubble spraying device so that the bubbles adhere to the inner wall of the pipeline; Transmit ultrasonic waves to the pipeline using the ultrasonic signal acquisition device, enhance the echo signal through the resonance of the bubbles, and perform axial scanning along the pipeline surface to obtain a series of echo signals; Filter the received echo signal to eliminate the influence of high-frequency noise signals; Perform a fast Fourier transform on the echo signal to obtain the spectrum of the echo signal; Pick up the position where the maximum peak of the spectrum is located to obtain a resonance peak sequence; Obtain the resonance peak outliers in the resonance peak sequence, and judge whether there are defects in the pipeline according to the resonance peak outliers.

[0005] According to some embodiments of the present invention, performing a fast Fourier transform on the echo signal to obtain the spectrum of the echo signal includes: Calculating the spectrum of the echo signal based on the fast Fourier transform formula. The fast Fourier transform formula is: In the formula, S(f) is the spectrum of the echo signal, fft() is the fast Fourier transform operator, s(t) is the echo signal, and t represents time.

[0006] According to some embodiments of the present invention, picking the position where the maximum peak of the spectrum is located to obtain a formant sequence includes: Calculating the spectrum based on the spectrum maximum value formula, and the spectrum maximum value formula is: In the formula, S max is the maximum value of the current spectrum, abs() represents taking the modulus of the spectrum, S(f) is the spectrum of the echo signal, and S max corresponds to the formant frequency f max ; S max corresponds to the formant frequency f max , and all echo signals obtained by axial movement and scanning along the pipe surface are processed in sequence to obtain a formant sequence F, where F = {f 1, f 2, f 3, ... , f n}.

[0007] According to some embodiments of the present invention, obtaining the formant outliers in the formant sequence and judging whether there are defects in the pipeline according to the formant outliers includes: Calculating the formant mean and formant standard deviation based on the mean calculation formula and the standard deviation calculation formula, and performing Z-Score normalization processing according to the formant mean and the formant standard deviation; The mean calculation formula is: In the formula, μ is the formant mean, and f i is the i-th value in the formant sequence F; The standard deviation calculation formula is: In the formula, σ is the standard deviation, μ is the formant mean, and f i is the i-th value in the formant sequence F; The Z-Score normalization processing formula is: In the formula, Z i is the formant normalization value, σ is the standard deviation, μ is the formant mean, and f i is the i-th value in the formant sequence F; If Z i is greater than the preset anomaly detection threshold, it is determined that the corresponding f i is a formant outlier, indicating that there are defects in the pipeline.

[0008] According to some embodiments of the present invention, the bubble spraying device includes a nozzle, an air pump, and a water pump, and the nozzle is respectively connected to the air pump and the water pump.

[0009] According to some embodiments of the present invention, the nozzle is in a cylindrical shape, and micropores are provided on the cylindrical surface of the nozzle. The nozzle includes an air inlet pipe and a water inlet pipe, the air inlet pipe is connected to the air pump, and the water inlet pipe is connected to the water pump.

[0010] According to some embodiments of the present invention, the air pump is provided with an air inlet hole and an air outlet hole, and the air outlet hole is connected to the air inlet pipe.

[0011] According to some embodiments of the present invention, the water pump is provided with a water inlet and a water outlet, and the water outlet is connected to the water inlet pipe.

[0012] According to some embodiments of the present invention, the ultrasonic signal acquisition device includes an ultrasonic probe, a signal excitation module, and an echo storage module. The ultrasonic probe is used for transmitting and receiving ultrasonic signals. The signal excitation module is used for generating a frequency-swept signal and supplying power to the ultrasonic probe. The echo storage module is used for storing the echo signals received by the ultrasonic probe.

[0013] According to some embodiments of the present invention, the ultrasonic signal acquisition device further includes a wireless communication module and a smart terminal. The wireless communication module is used for transmitting the data in the echo storage module to the smart terminal, and the smart terminal is used for performing fast Fourier transform, resonance peak picking, and defect type judgment on the echo signals.

[0014] The embodiments of the present invention have at least the following beneficial effects: The bubble spraying device is used to spray bubbles inside the pipeline, enabling the bubbles to adhere to the inner wall of the pipeline, thereby providing environmental support for subsequent ultrasonic detection. The ultrasonic signal acquisition device emits ultrasonic waves to stimulate the bubbles adhering to the inner wall of the pipeline to resonate, thereby enhancing the echo signal and improving the detection sensitivity and signal-to-noise ratio. After receiving the echo signal, the ultrasonic signal acquisition device first performs filtering to remove high-frequency noise signals to ensure the accuracy of subsequent analysis, and then converts the echo signal into a spectrum through the fast Fourier transform algorithm to facilitate the identification of signal characteristics. The position of the maximum peak is picked up on the spectrum to obtain the resonance peak sequence, and then the resonance peak outliers are selected from it. These resonance peak outliers reflect the possible defect areas on the inner wall of the pipeline. Based on the analysis of the resonance peak outliers, it is possible to effectively determine whether there are defects or damages in the pipeline, thereby realizing the non-destructive detection of the inner wall defects of the pipeline. A broadband excitation signal is used to excite the bubble film on the surface of the inner wall of the pipeline, inducing non-linear resonance or spectral distortion. The echo signal is filtered and subjected to fast Fourier transform to obtain the resonance peak outliers in the resonance peak sequence, and whether there are defects in the pipeline is judged according to the resonance peak outliers, thereby realizing the identification of minor defects in the pipeline and improving the defect identification rate.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 is a flowchart of the pipeline defect detection method according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of the ultrasonic detection process of the pipeline defect detection method according to an embodiment of the present invention; Figure 3 is a schematic spectrum diagram obtained by performing fast Fourier transform on the echo signal of the pipeline defect detection method according to an embodiment of the present invention; Figure 4 is a schematic diagram for judging whether there are defects in the pipeline according to the resonance peak outliers of the pipeline defect detection method according to an embodiment of the present invention; Figure 5 is a schematic structural diagram of the nozzle of the bubble spraying device of the pipeline defect detection system according to an embodiment of the present invention; Figure 6 is a schematic structural diagram of the air pump of the bubble spraying device of the pipeline defect detection system according to an embodiment of the present invention; Figure 7 is a schematic structural diagram of the water pump of the bubble spraying device of the pipeline defect detection system according to an embodiment of the present invention; Figure 8 The functional block diagram of the ultrasonic signal acquisition device of the pipeline defect detection system according to the embodiment of the present invention.

[0017] Reference numerals: Bubble spraying device 100, nozzle 110, micropores 111, air inlet pipe 112, water inlet pipe 113, air pump 120, air inlet hole 121, air outlet hole 122, water pump 130, water inlet 131, water outlet 132, ultrasonic signal acquisition device 200, ultrasonic probe 210, signal excitation module 220, echo storage module 230, wireless communication module 240, intelligent terminal 250, pipeline 300, pipeline crack 310, bubble 320. Detailed implementation manners

[0018] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention, and should not be construed as a limitation to the present invention.

[0019] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0020] In the description of the present invention, "several" means one or more, "multiple" means more than two, greater than, less than, exceeding, etc. are understood as not including the present number, and "above", "below", "within", etc. are understood as including the present number. If terms such as "first" and "second" are described, they are only used to distinguish technical features and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0021] In the description of the present invention, unless otherwise clearly defined, terms such as "set", "installed", "connected", and "coupled" should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0022] To improve the sensitivity and adaptability of crack detection, resonant ultrasonic testing methods have been tried, such as stimulating the tested area to generate local structural resonance and observing changes in frequency response. However, this method usually relies on the macroscopic vibration characteristics of the overall structure, and the resolution of local minor defects is still limited. In addition, factors such as local coupling conditions and surface roughness can also interfere with the stability of the detection results. There is an urgent need for a detection method that can accurately identify tiny cracks or local damage without relying on a complete reflection path and has good environmental adaptability to meet the needs of online monitoring of complex structures or high-risk areas.

[0023] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments.

[0024] See also Figures 1 to 4 This embodiment discloses a pipeline defect detection system, comprising a bubble spraying device 100 and an ultrasonic signal acquisition device 200. The bubble spraying device 100 is used to spray bubbles within a pipeline 300, causing the bubbles to adhere to the inner wall of the pipeline 300. The ultrasonic signal acquisition device 200 uses a broadband excitation signal to excite the bubble film on the inner wall of the pipeline 300, inducing nonlinear resonance or spectral distortion. The ultrasonic signal acquisition device 200 then analyzes and processes the echo signal to identify minor defects in the pipeline 300.

[0025] See also Figure 1 This embodiment provides a method for detecting pipeline defects using the above pipeline defect detection system, which mainly includes steps S101 to S106: S101 , using the bubble spraying device 100 to spray bubbles 320 in the pipe 300 , so that the bubbles 320 adhere to the inner wall of the pipe 300 .

[0026] S102: Ultrasonic wave acquisition device 200 transmits ultrasonic waves into pipe 300, enhancing the echo signal through bubble resonance. The ultrasonic wave acquisition device 200 then scans along the axial surface of pipe 300 to obtain a series of echo signals. Ultrasonic wave acquisition device 200 uses a broadband excitation signal to excite the bubble film on the inner wall of pipe 300, inducing nonlinear resonance or spectral distortion, thereby enhancing the echo signal.

[0027] S103: Filter the received echo signal to remove the influence of high-frequency noise signals.

[0028] S104: Perform fast Fourier transform on the echo signal to obtain the frequency spectrum of the echo signal.

[0029] S105 , picking up the position of the maximum peak of the spectrum to obtain a resonance peak sequence.

[0030] S106 , obtaining a resonance peak abnormality value in the resonance peak sequence, and determining whether the pipeline 300 has a defect based on the resonance peak abnormality value.

[0031] It should be noted that before the step of spraying the bubbles 320 in the pipeline 300 by using the bubble spraying device 100 in the above step S101, it is necessary to remove the dirt on the inner wall of the pipeline 300 first, so as to facilitate the attachment of the bubbles 320 to the inner wall of the pipeline 300. After the step of judging whether there are defects in the pipeline 300 according to the resonance peak abnormal value in the above step S106, it is also necessary to clean the inner wall of the pipeline 300 to remove the bubbles 320 attached to the inner wall of the pipeline 300.

[0032] The filtering process of the received echo signal in the above step S103 is to filter the original echo signal s0(t) received by the probe by setting the cut-off frequency of the low-pass filter H(t) to 1 MHz, and obtain the filtered echo signal s(t).

[0033] Please refer to Figure 3 , the fast Fourier transform of the echo signal in the above step S104 to obtain the spectrum of the echo signal includes: Calculating the spectrum of the echo signal based on the fast Fourier transform formula, and the fast Fourier transform formula is: In the formula, S(f) is the spectrum of the echo signal, fft() is the fast Fourier transform operator, s(t) is the echo signal, and t represents time.

[0034] It should be noted that the step of picking the position where the maximum peak of the spectrum is located in the above step S105 to obtain the resonance peak sequence includes: Calculating the spectrum based on the formula for taking the maximum value of the spectrum, and the formula for taking the maximum value of the spectrum is: In the formula, S max is the maximum value of the current spectrum, abs() represents taking the modulus of the spectrum, S(f) is the spectrum of the echo signal, and S max corresponds to the resonance peak frequency f max ; Processing all the echo signals obtained by axial movement and scanning along the surface of the pipeline 300 in sequence to obtain the resonance peak sequence F, where F = {f 1, f 2, f 3, ... , f n}.

[0035] The obtaining of the resonance peak abnormal value in the resonance peak sequence in the above step S106 includes: Calculate the formant mean and formant standard deviation based on the mean calculation formula and the standard deviation calculation formula, and perform Z-Score standardization processing according to the formant mean and formant standard deviation; that is, use the outlier detection method based on the standard deviation (Z-Score method) to obtain the formant outliers in the formant sequence.

[0036] The mean calculation formula is: where μ is the formant mean, and f i is the i-th value in the formant sequence F; The standard deviation calculation formula is: where σ is the standard deviation, μ is the formant mean, and f i is the i-th value in the formant sequence F; The Z-Score standardization processing formula is: where Z i is the formant standardized value, σ is the standard deviation, μ is the formant mean, and f i is the i-th value in the formant sequence F; If Z i is greater than the preset outlier detection threshold T, then it is determined that the corresponding f i is a formant outlier, indicating that the pipeline 300 has a defect.

[0037] Please refer to Figure 4 , generally, the outlier detection threshold T for the pipeline crack 310 is set to 10 Hz, and the outlier detection threshold T for the corrosion defect is set to 20 Hz. If 10 ≤ Z i ≤ 20, then it is determined that the pipeline 300 has a crack defect; if Z i > 20, then it is determined that the pipeline 300 has a corrosion defect.

[0038] Then output the set of formant outliers and their corresponding indices, as follows: where A is the set of formant outliers, B is the index number corresponding to the formant outlier, F is the formant sequence, and f i is the i-th formant outlier in the formant sequence F, Z i is the formant standardized value, and T is the outlier detection threshold.

[0039] Finally, obtain the location of the pipeline defect according to the index number of the formant outlier.

[0040] Please refer toFigure 5 , Figure 6 and Figure 7 , the bubble spraying device 100 includes a spray head 110, an air pump 120 and a water pump 130. The spray head 110 is respectively connected to the air pump 120 and the water pump 130. The spray head 110 in the bubble spraying device 100 is used to spray the liquid with bubbles 320 onto the surface of the workpiece at a specific pressure and spraying speed, achieving a uniform and delicate spraying effect. The function of the air pump 120 is to provide compressed air, where the bubbles 320 are generated; the compressed air is mixed with the liquid through the spray head 110 to form a gas-liquid mixed fluid with tiny bubbles. The water pump 130 is responsible for pressurizing and transporting the liquid to the spray head 110, ensuring that the spray head 110 can form a continuous and stable liquid flow. After the air pump 120 is started, it generates compressed air and transports it into the spray head 110. At the same time, the water pump 130 presses the liquid to the spray head 110. The liquid and the compressed air in the spray head 110 are mixed inside the spray head 110 to form a gas-liquid mixed fluid with a large number of tiny bubbles. This gas-liquid mixed fluid is ejected from the spray head 110 at a certain speed and pressure and evenly sprayed onto the inner wall of the pipeline 300 to be detected, thereby achieving an efficient spraying effect.

[0041] Please refer to Figure 5 , the spray head 110 is in a cylindrical shape. Micro holes 111 are provided on the cylindrical surface of the spray head 110. The spray head 110 includes an air inlet pipe 112 and a water inlet pipe 113. The air inlet pipe 112 is connected to the air pump 120, and the water inlet pipe 113 is connected to the water pump 130. The spray head 110 is in a cylindrical shape, and the processed gas and water are ejected through the micro holes 111 provided on its surface. The air inlet pipe 112 is connected to the air pump 120, and compressed air is transported to the spray head 110 through the air inlet pipe 112; the water inlet pipe 113 is connected to the water pump 130, and water is transported to the spray head 110 through the water inlet pipe 113. The gas and water inside the spray head 110 are mixed at the micro holes 111 and ejected at a high speed. The air pump 120 transports compressed air and other gases to the spray head 110 through the air inlet pipe 112. At the same time, the water pump 130 transports water to the spray head 110 through the water inlet pipe 113. The gas and water are mixed at the micro holes 111 on the surface of the spray head 110 and ejected at a high speed, completing the spraying of bubbles 320 inside the pipeline 300 so that the bubbles 320 adhere to the inner wall of the pipeline 300.

[0042] Please refer to Figure 6, the air pump 120 is provided with an air inlet hole 121 and an air outlet hole 122, and the air outlet hole 122 is connected to the air inlet pipe 112. The function of the air pump 120 is to provide compressed air. The air inlet hole 121 it is provided with is used to introduce external air, and the air outlet hole 122 is used to output the compressed air. The air inlet pipe 112 is connected to the air outlet hole 122, so the compressed air can be transmitted to the spray head 110 through the air inlet pipe 112. When the air pump 120 is started, it will inhale air through the air inlet hole 121, then compress it, and the compressed air is discharged from the air outlet hole 122 and transmitted to the spray head 110 through the air inlet pipe 112, thereby completing the spraying of bubbles 320 in the pipeline 300 so that the bubbles 320 adhere to the inner wall of the pipeline 300.

[0043] Please refer to Figure 7 , the water pump 130 is provided with a water inlet 131 and a water outlet 132, and the water outlet 132 is connected to the water inlet pipe 113. The water inlet 131 is used to introduce the liquid to be transported, and the water outlet 132 is responsible for transporting the liquid pumped out by the water pump to the spray head 110. The water inlet pipe 113 is used to connect the water outlet 132 of the water pump 130 and further guide the transported liquid to the spray head 110. When the water pump 130 works, the impeller rotates to generate centrifugal force, flinging the liquid introduced through the water inlet 131 in all directions, transporting the liquid through the water outlet 132 to the connected water inlet pipe 113, and continuing to transport it to the spray head 110 to achieve efficient pumping of the liquid.

[0044] Please refer to Figure 8 , the ultrasonic signal acquisition device 200 includes an ultrasonic probe 210, a signal excitation module 220, and an echo storage module 230. The ultrasonic probe 210 is used to transmit and receive ultrasonic signals. The signal excitation module 220 is used to generate a swept-frequency signal and supply power to the ultrasonic probe. The echo storage module 230 is used to store the echo signals received by the ultrasonic probe. The main function of the ultrasonic probe 210 is to transmit and receive ultrasonic signals, capable of generating ultrasonic pulses on the object to be detected and capturing the echo signals reflected by the object. The signal excitation module 220 is responsible for generating a swept-frequency signal and providing necessary power supply for the ultrasonic probe to ensure the normal transmission of ultrasonic waves. The echo storage module 230 receives and stores the echo signals received by the ultrasonic probe, providing a basis for subsequent data processing and analysis. By generating a swept-frequency signal through the signal excitation module 220, the ultrasonic probe 210 is driven to emit ultrasonic waves; the ultrasonic waves propagate in the pipeline 300 to be detected and are reflected back to the ultrasonic probe 210 to form echo signals; the echo signals are captured by the ultrasonic probe 210 and transmitted to the echo storage module 230 for storage.

[0045] Please refer to Figure 8, the ultrasonic signal acquisition device 200 further includes a wireless communication module 240 and an intelligent terminal 250. The wireless communication module 240 is used to transmit the data in the echo storage module 230 to the intelligent terminal 250, and the intelligent terminal 250 is used to perform fast Fourier transform, formant picking, and defect type judgment on the echo signal. The echo storage module 230 is responsible for storing the echo signals obtained during the ultrasonic detection process; the role of the wireless communication module 240 is to wirelessly send the echo signal data stored in the echo storage module 230 to the intelligent terminal 250. After receiving these echo signal data, the intelligent terminal 250 performs fast Fourier transform on the echo signal. The method of converting the time-domain signal into a frequency-domain signal helps to identify the ability of specific frequency components in the signal. For example, the intelligent terminal 250 is a tablet computer or a smart phone, installed with upper computer software. By processing the echo signal through the upper computer software, the abnormal values of the formants can be obtained, that is, those frequency peaks that may indicate potential problems or abnormal conditions. According to the formant abnormal values, it is judged whether there are defects in the pipeline, and finally a pipeline detection report is generated.

[0046] Before detection, first remove the dirt on the inner wall of the pipeline 300 to facilitate the attachment of the bubbles 320 to the inner wall of the pipeline 300. Then use the spray head 110 to spray the bubbles 320 inside the pipeline so that the bubbles 320 can adhere to the inner wall of the pipeline 300. During detection, use the ultrasonic probe 210 to sequentially perform ultrasonic scanning along the surface of the pipeline 300. The ultrasonic wave excites the bubbles 320 attached to the inner wall of the pipeline 300 to resonate, thereby enhancing the echo signal. After the ultrasonic probe 210 receives the echo signal, first perform filtering processing to remove high-frequency noise signals to ensure the accuracy of subsequent analysis; use the wireless communication module 240 to transmit these echo signal data to the intelligent terminal 250; the intelligent terminal 250 analyzes the abnormal values of the formants by performing fast Fourier transform processing on the echo signal data, so as to realize the detection of the defect situation of the pipeline 300, and finally generate a pipeline detection report. After detection, clean the inner wall of the pipeline 300 to remove the bubbles 320 attached to the inner wall of the pipeline 300. Adopt a broadband excitation signal to excite the bubble film on the inner wall surface of the pipeline 300, induce non-linear resonance or spectral distortion, perform filtering processing and fast Fourier transform on the echo signal, obtain the abnormal values of the formants in the formant sequence, and judge whether there are defects in the pipeline 300 according to the formant abnormal values, which can effectively judge whether there are defects or damages in the pipeline 300, and realize the identification of minor defects in the pipeline 300, improving the defect identification rate.

[0047] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the knowledge scope of those of ordinary skill in the art to which the present invention pertains, various changes can be made without departing from the purpose of the present invention.

Claims

1. A pipeline defect detection method, based on a pipeline defect detection system, characterized in that, The detection system includes a bubble spraying device and an ultrasonic signal acquisition device, and the detection method includes: Using the bubble spraying device to spray bubbles in the pipeline so that the bubbles adhere to the inner wall of the pipeline; Using the ultrasonic signal acquisition device to emit ultrasonic waves to the pipeline, enhancing the echo signal through the way of bubble resonance, and axially moving and scanning along the pipeline surface to obtain a series of echo signals; Performing filtering processing on the received echo signals to eliminate the influence of high-frequency noise signals; Performing a fast Fourier transform on the echo signals to obtain the spectrum of the echo signals; Picking up the position where the maximum peak of the spectrum is located to obtain a resonance peak sequence; Obtaining the resonance peak outliers in the resonance peak sequence, and judging whether there are defects in the pipeline according to the resonance peak outliers.

2. The pipeline defect detection method according to claim 1, characterized in that The performing a fast Fourier transform on the echo signals to obtain the spectrum of the echo signals includes: Calculating the spectrum of the echo signals based on the fast Fourier transform formula, and the fast Fourier transform formula is: Wherein, S(f) is the spectrum of the echo signals, fft() is the fast Fourier transform operator, s(t) is the echo signal, and t represents time.

3. The pipeline defect detection method according to claim 2, wherein The picking up the position where the maximum peak of the spectrum is located to obtain a resonance peak sequence includes: Calculating the spectrum based on the formula for taking the maximum value of the spectrum, and the formula for taking the maximum value of the spectrum is: where S max is the maximum value of the current spectrum, abs() represents taking the modulus of the spectrum, and S(f) is the spectrum of the echo signal; S max The corresponding frequency is the resonance peak f max , and all echo signals obtained by axially moving and scanning along the pipe surface are processed in sequence to obtain a resonance peak sequence F, where F = {f 1, f 2, f 3, ... , f n }.

4. The pipeline defect detection method according to claim 3, wherein, The obtaining the resonance peak outliers in the resonance peak sequence, and judging whether there are defects in the pipeline according to the resonance peak outliers includes: Calculating the resonance peak mean value and the resonance peak standard deviation based on the mean value calculation formula and the standard deviation calculation formula, and performing Z-Score normalization processing according to the resonance peak mean value and the resonance peak standard deviation; The mean value calculation formula is: where μ is the mean value of the resonance peak, and f i is the i-th value in the resonance peak sequence F; The standard deviation calculation formula is: where σ is the standard deviation, μ is the mean of the formants, and f i is the i-th value in the formant sequence F; The Z-Score normalization processing formula is: where Z i is the resonance peak normalization value, σ is the standard deviation, μ is the resonance peak mean value, and f i is the i-th value in the resonance peak sequence F; If Z i is greater than the preset anomaly detection threshold, it is determined that the corresponding f i is a formant anomaly value, indicating that there is a defect in the pipeline.

5. The pipeline defect detection method according to claim 1, wherein, The bubble spraying device includes a spray head, an air pump and a water pump, and the spray head is respectively connected to the air pump and the water pump.

6. The pipeline defect detection method according to claim 5, wherein The spray head is in a cylindrical shape, micropores are arranged on the cylindrical surface of the spray head, the spray head includes an air inlet pipe and a water inlet pipe, the air inlet pipe is connected to the air pump, and the water inlet pipe is connected to the water pump.

7. The pipeline defect detection method according to claim 6, characterized in that The air pump is provided with an air inlet hole and an air outlet hole, and the air outlet hole is connected to the air inlet pipe.

8. The pipeline defect detection method according to claim 6, wherein The water pump is provided with a water inlet and a water outlet, and the water outlet is connected to the water inlet pipe.

9. The pipeline defect detection method according to claim 5, wherein The ultrasonic signal acquisition device includes an ultrasonic probe, a signal excitation module and an echo storage module. The ultrasonic probe is used for transmitting and receiving ultrasonic signals. The signal excitation module is used for generating a frequency-swept signal and supplying power to the ultrasonic probe. The echo storage module is used for storing the echo signals received by the ultrasonic probe.

10. The pipeline defect detection method according to claim 9, wherein, The ultrasonic signal acquisition device further includes a wireless communication module and a smart terminal. The wireless communication module is used for transmitting the data in the echo storage module to the smart terminal, and the smart terminal is used for performing a fast Fourier transform, resonance peak picking and defect type judgment on the echo signals.

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