Method for detecting bubbles in fluid (non-gas)

Abstract

The invention belongs to the technical field of fluid detection and nondestructive detection, and discloses a method for detecting bubbles in fluid (non-gas). According to the method, a multi-channel ultrasonic probe is fixedly installed on a pipeline installation plane, the ultrasonic excitation / receiving module excites the multi-channel ultrasonic probe, echo signals sequentially pass through the adjustable gain amplification module, the filtering module and the high-speed data acquisition module and then are converted into digital quantity, and the digital quantity is read by the FPGA. And the driving touch display module displays the echo signal and detection parameter setting options (detection parameters can be set through a PC host, a peripheral host, a cloud end or an FPGA module), and when the echo signal exceeds a preset alarm threshold value, an alarm signal can be output to the outside. Through an Ethernet TCP / IP protocol, the FPGA can send an echo signal or a detection result to a PC host, a peripheral host or a cloud end, thereby realizing master-slave connection, remote control, remote diagnosis and analysis, fault pre-judgment and full life cycle prediction.

Description

Technical Field

[0001] The invention belongs to the technical field of fluid detection and non-destructive detection, and specifically relates to a method for detecting bubbles in a fluid (non-gas). Background Art

[0002] Since bubbles in fluids can cause medical diseases, corrosion, or yield issues, it is necessary to detect bubbles in fluids and implement strict control, such as in the fields of medical safety, food processing, smart manufacturing, and aerospace.

[0003] In the field of medical safety, venous gas (bubble or hidden bubble) embolism usually occurs in the body after diving decompression. The volume of bubbles is positively correlated with decompression sickness, so the detection of bubble volume is used to evaluate the risk of decompression sickness. During hemodialysis, air enters the body from the extracorporeal circulation and causes vascular embolism (air embolism). In mild cases, there are paroxysmal coughing, shortness of breath, chest tightness, chest pressure, cyanosis, wheezing, and difficulty breathing. In severe cases, there are convulsions, confusion, coma, and death. Therefore, the air in the dialysis circulation loop should be strictly detected. The ultrasonic method has the advantages of fast monitoring speed, high sensitivity, and high repetition frequency, and can monitor venous gas embolism and vascular embolism in real time.

[0004] In the field of food processing, ultrasonic technology can be used to detect and remove foreign matter in liquid food; it can also be used to evaluate the density and viscosity of rheological foods, such as liquid foods, dairy products, jams, etc.; it can also be used to detect the bubble content in food, such as the vacuum degree of canned or bagged food. At the same time, conventional ultrasonic detection methods cannot be connected to the cloud through Ethernet, and thus cannot achieve high-level detection requirements such as master-slave connection and remote control.

[0005] In the field of intelligent manufacturing, sealing and gluing are required between structural parts during automobile production, such as doors, bodies, front and rear covers, front and rear windshields, and sunroofs. The quality of sealing and gluing affects the sealing, corrosion resistance, and production rhythm of the vehicle. The hose loop is one of the main links in the body gluing to produce bubbles. Due to the existence of high-pressure bubbles, the bubbles will burst when they come out of the hose, affecting the glue line and causing the glue production line to be temporarily shut down. Therefore, it is necessary to detect the bubbles in the hose loop and discharge the bubble-containing glue section in advance to improve manufacturing quality control. Using 2D or 3D visual cameras to detect the glue line breakage or the outer contour of the glue line after glue is discharged, it is impossible to detect the bubbles inside the glue line, and thus it is impossible to detect bubbles before glue is discharged (detection inside the hose); in the production of photosensitive film, if there are bubbles in the photosensitive emulsion, after coating and drying, there will be a defect without a photosensitive layer at the bubble rupture, resulting in defective waste. Therefore, it is necessary to detect whether there are bubbles in the photosensitive glue before coating. Multi-channel ultrasonic probes are often used to measure bubbles in photosensitive adhesive tubes. By analyzing the sound field and reasonably arranging the ultrasonic probes, bubbles in the photosensitive adhesive can be effectively detected. However, the system composition is isolated and cannot meet the high detection background requirements such as multi-machine networking and remote control.

[0006] In the aerospace field, bubbles and cavitation mixed in the hydraulic system and fuel supply system pipelines will cause the hydraulic pipelines to work unstably, generate noise and vibration, cavitation damage, and oil quality deterioration. Reasonable prediction of bubbles and cavitation is crucial to the hydraulic system. Machine vision methods are often used to detect bubbles in gas-liquid two-phase flow, and bubbles in the image are identified by image acquisition, image enhancement, binarization, boundary recognition and other means. At the same time, due to the use of visual methods, it is necessary to open windows or implant cameras in the pipeline, which limits its application in high temperature, high pressure, and corrosive fluid media. Summary of the invention

[0007] The purpose of the present invention is to address the phenomenon of bubbles in fluid (non-gas) in pipelines, taking into account the versatility of multiple detection scenarios, and propose a multi-channel ultrasonic bubble detection method based on FPGA, which can effectively detect bubbles in pipelines. By selecting an adapted ultrasonic probe, when bubbles are detected in the fluid (non-gas) and exceed the threshold, the FPGA will output an alarm signal to the outside. At the same time, the FPGA can be connected to the cloud via Ethernet to achieve master-slave connection, remote control, and remote diagnosis and analysis.

[0008] The present invention provides a method for detecting bubbles in a fluid (non-gas). The system used in the detection method is composed of multiple groups of ultrasonic probes, an FPGA module, an Ethernet communication module, a switch, an ultrasonic excitation / receiving module, an adjustable gain amplification module, a data acquisition module, a touch display module, an IO module, a PC host, a peripheral host and a cloud.

[0009] Among them, the ultrasonic excitation / reception module can excite and receive multiple sets of ultrasonic probes;

[0010] The specific detection method steps are as follows:

[0011] 1) According to the acoustic attenuation coefficient of different fluids (non-gas) Determine the working frequency of the ultrasonic probe, reduce the attenuation of the ultrasonic sound pressure and sound intensity by the fluid, so that the ultrasonic detection sensitivity of this frequency meets the minimum detection bubble requirement, where η is the fluid viscosity coefficient and c is the ultrasonic sound velocity in the fluid;

[0012] 2) Calculate the propagation path of a single set of ultrasonic probe beams in the pipe wall and fluid medium (such as Figure 2 ), Then determine the number of ultrasonic probe groups N, i.e. the number of channels, required for the ultrasonic beam to fully cover the fluid medium in the pipeline;

[0013] Among them, α1 is the incident angle of the ultrasonic wave in the pipe wall, α2 is the refraction angle of the ultrasonic wave in the fluid medium, c1 is the sound speed of the ultrasonic wave in the pipe wall, and c2 is the sound speed of the ultrasonic wave in the fluid medium;

[0014] 3) Determine the installation rotation angle between adjacent ultrasonic probe groups according to step 2) (like Figure 2 );

[0015] 4) According to the actual installation conditions, two methods can be used to fix the ultrasonic probe (such as Figure 3 ), one is to mill out the i-th group of ultrasonic probe installation planes at the i-th installation point of the pipeline, and the other is to add a semicircular sleeve at the i-th installation point of the pipeline and mill out the i-th group of ultrasonic probe installation planes;

[0016] 5) Debug the system and set the N-channel ultrasonic probe working mode, repetition frequency, fluid medium sound velocity, excitation voltage, pulse width, gain, translation, detection range, sampling rate, data compression ratio, filtering and other detection parameters through the PC host, peripheral host, cloud or FPGA module;

[0017] 6) Use epoxy resin glue to fix the N-channel ultrasonic probe to the pipeline installation plane, fine-tune the probe to make it fit completely with the installation plane, and clamp it continuously for 24 hours under external force to allow the epoxy resin colloid to completely solidify;

[0018] 7) After the epoxy resin colloid in step 6) is completely solidified, a sound-absorbing coating with a large acoustic impedance is sprayed on the circumferential area outside the ultrasonic probe installation plane of all detection measuring points;

[0019] 8) According to the minimum detection bubble requirement, use standard samples to calibrate the N channel and set the alarm threshold;

[0020] 9) In the above steps, the system starts to detect bubbles in the fluid. When it is detected that the volume of bubbles exceeds the set alarm threshold (that is, the ultrasonic amplitude is lower than the alarm gate height), the system outputs an alarm IO signal to the outside; as a slave, the system supports multi-machine networking, master-slave connection, and cloud functions. The slave detection results can be summarized to the switchboard, and then sent to the cloud by the switchboard, thereby realizing remote control, remote diagnosis and analysis, fault prediction, and full life cycle prediction.

[0021] The bubble detection method in fluid (non-gas) provided by the present invention calculates the propagation path of the ultrasonic sound beam in the pipe wall and the fluid medium for different pipe diameters, and combines the focusing effect of the inner surface of the pipe on the ultrasonic sound beam of the selected frequency, and the focal column diameter Focal column length Reasonably plan the number of ultrasonic probe channels to fully cover the fluid medium in the pipeline, where λ is the ultrasonic wavelength, F is the focal length, and D is the chip diameter.

[0022] The bubble detection method in fluid (non-gas) provided by the present invention is to coat the circumferential surface outside the cross section of the ultrasonic probe with a sound-absorbing coating with large acoustic impedance to eliminate multiple reflected waves other than direct waves and improve detection sensitivity.

[0023] The bubble detection method in fluid (non-gas) provided by the present invention can be externally connected to a B / C scanning device through an IO module, and the trigger intervals of the X-axis and the Y-axis are adjustable (0.1-2 mm) to meet different detection accuracy requirements.

[0024] The present invention provides a method for detecting bubbles in fluid (non-gas). The ultrasonic excitation / receiving module can excite a multi-channel ultrasonic probe. The pulse width of each channel ultrasonic probe is adjustable (20ns~2.5us, increment 2ns), and the excitation voltage of each channel ultrasonic probe is adjustable (150 / 200 / 250V) to match ultrasonic probes of different frequencies to meet different fluid detection requirements.

[0025] The present invention provides a method for detecting bubbles in fluid (non-gas). The adjustable gain amplification module can receive multi-channel ultrasonic probe echo signals. The gain of each channel is adjustable (-20 to 60 dB, with an increment of 0.5 dB). The gain is controlled by an FPGA module to achieve program-controlled amplification of ultrasonic signals.

[0026] The present invention provides a method for detecting bubbles in a fluid (non-gas), wherein the data acquisition module is composed of a multi-channel A / D acquisition unit, and the translation (delayed sampling length) and detection range (sampling length) of each A / D acquisition unit can be set separately, with a translation of 0 to 65535 sampling points and a detection range of 0 to 65535 sampling points.

[0027] The present invention provides a method for detecting bubbles in fluid (non-gas), wherein the sampling rate of each channel of a multi-channel A / D acquisition unit is adjustable (125.00 / 62.50 / 25.00 / 5.00 MHz) to satisfy the Nyquist sampling theorem between the sampling frequency and the signal frequency.

[0028] The present invention provides a method for detecting bubbles in fluids (non-gases). The system acts as a slave and compresses the multi-channel detection data according to a data compression ratio (1 to 10). The data is then transmitted to a PC host, an external host or the cloud via an Ethernet communication module using the Ethernet TCP / IP protocol, thereby solving the transmission bandwidth limitation and tracing the on-site detection data.

[0029] The present invention provides an application of a method for detecting bubbles in fluids (non-gases), realizing non-contact, high-beat, and advanced detection, and can detect bubbles in advance, and then execute related operation processes to avoid blocking subsequent process flows. The system supports multi-machine networking, master-slave connection, and cloud functions, realizing remote control, remote diagnosis and analysis, fault prediction, and full life cycle prediction.

[0030] The present invention has the following advantages:

[0031] 1) According to the acoustic attenuation coefficient of different fluids (non-gas), different ultrasonic probes are matched to improve the detection sensitivity.

[0032] 2) Arrange ultrasonic probes at multiple detection points to fully cover the circumference of the pipeline, achieve full coverage detection, and reduce the bubble missed detection rate.

[0033] 3) The detection repetition frequency is as high as 10kHz, which can meet the real-time, high-beat and advanced detection of bubbles in high-speed fluids.

[0034] 4) Combined with corresponding mechanical scanning devices, the system is compatible with A-scan, B-scan and C-scan display functions.

[0035] 5) The bubble detection system consists of FPGA module, Ethernet communication module, IO module, ultrasonic excitation / receiving module, adjustable gain amplifier module, data acquisition module, touch display module, ultrasonic probe and installation components. When bubbles are detected, the system can output an alarm signal. At the same time, it can be connected to the cloud through Ethernet to realize multi-machine networking, master-slave connection, remote control, and remote diagnosis and analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The bubble detection system in fluid (non-gas) consists of;

[0037] Figure 2Schematic diagram of ultrasonic beam propagation path and installation rotation angle of adjacent ultrasonic probes, where (a) the installation of the front probe of adjacent ultrasonic probes, (b) the installation of the rear probe of adjacent ultrasonic probes, and the installation rotation angle of adjacent ultrasonic probes is Δβ;

[0038] Figure 3 Schematic diagram of the arrangement and installation of ultrasonic probes for bubble detection in fluid (non-gas) in pipelines, where (a) is milling fixed installation and (b) is semicircular sleeve fixed installation;

[0039] Figure 4 Ultrasonic waveform when no bubbles are detected in the fluid (non-gas);

[0040] Figure 5 Ultrasonic waveform when bubbles are detected in a fluid (not gas). DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0042] Example 1

[0043] A system for detecting bubbles in a fluid (non-gas) is composed of multiple sets of ultrasonic probes, FPGA modules, Ethernet communication modules, switches, ultrasonic excitation / receiving modules, adjustable gain amplifier modules, data acquisition modules, touch display modules, IO modules, PC hosts, peripheral hosts and cloud. Figure 1 ); wherein the ultrasonic excitation / reception module can excite and receive multiple sets of ultrasonic probes.

[0044] The specific parameter range of the fluid (non-gas) bubble detection system is as follows: the excitation voltage of the ultrasonic excitation / receiving module is 150 / 200 / 250V, the repetition frequency is 500Hz~5kHz, the pulse width is 20ns~2.5us, the gain of the adjustable gain amplifier module is -20~60dB (increment 0.5dB), the A / D sampling rate of the data acquisition module is 125.00 / 62.50 / 25.00 / 5.00MHz, the translation (delay sampling length) is 0~65535 sampling points, the detection range (sampling length) is 0~65535 sampling points, the gate starting point is 0~65535 sampling points, the gate width is 0~65535 sampling points, the data compression ratio is 1~10, the ultrasonic probe frequency is 2.5~25MHz, the number of channels is 1~10, and the ultrasonic probe transceiver mode is spontaneous transmission and self-reception, single transmission and single reception. The above system was used to detect bubbles in a 304 stainless steel rubber hose (12 mm inner diameter, 7 mm wall thickness) under the parameter configuration shown in Table 1.

[0045] Table 1 Specific detection parameter configuration table of fluid (non-gas) bubble detection system

[0046]

[0047]

[0048] The above system is used to detect bubbles in the pipeline. The specific steps are as follows:

[0049] Step 1) According to the acoustic attenuation coefficient of different fluids (non-gas) Determine the working frequency of the ultrasonic probe, reduce the attenuation of the ultrasonic sound pressure and sound intensity by the fluid, so that the ultrasonic detection sensitivity of this frequency meets the minimum detection bubble requirement, where η is the fluid viscosity coefficient and c is the ultrasonic sound velocity in the fluid;

[0050] Step 2) Calculate the propagation path of a single set of ultrasonic probe sound beams in the pipe wall and fluid medium, Then determine the number of ultrasonic probe groups N, i.e. the number of channels, required for the ultrasonic beam to fully cover the fluid medium in the pipeline;

[0051] Among them, α1 is the incident angle of the ultrasonic wave in the pipe wall, α2 is the refraction angle of the ultrasonic wave in the fluid medium, c1 is the sound speed of the ultrasonic wave in the pipe wall, and c2 is the sound speed of the ultrasonic wave in the fluid medium;

[0052] Step 3) Determine the installation rotation angle between adjacent ultrasonic probe groups according to step 2)

[0053] Step 4) According to the actual installation conditions, two methods can be used to fix the ultrasonic probe. One method is to mill the i-th group of ultrasonic probe installation planes at the i-th installation point of the pipeline. The other method is to add a semicircular sleeve at the i-th installation point of the pipeline and mill the i-th group of ultrasonic probe installation planes.

[0054] Step 5) Debug the system and set the N-channel ultrasonic probe working mode, repetition frequency, fluid medium sound velocity, excitation voltage, pulse width, gain, translation, detection range, sampling rate, data compression ratio, filtering and other detection parameters through the PC host, peripheral host, cloud or FPGA module;

[0055] Step 6) Use epoxy resin glue to fix the N-channel ultrasonic probe to the pipeline installation plane, fine-tune the probe to make it fit completely with the installation plane, and continue to clamp it under external force for 24 hours to allow the epoxy resin colloid to completely solidify;

[0056] Step 7) After the epoxy resin colloid in step 6) is completely solidified, a sound-absorbing coating with a large acoustic impedance is sprayed on the circumferential area outside the ultrasonic probe installation plane at all detection points;

[0057] Step 8) according to the minimum bubble detection requirement, the N channel is calibrated using a standard sample and the alarm threshold is set;

[0058] Step 9) In the above steps, the system starts to detect bubbles in the fluid. When the volume of bubbles detected exceeds the set alarm threshold (that is, the ultrasonic amplitude is lower than the alarm gate height), the system outputs an alarm IO signal to the outside. The system supports multi-machine networking, master-slave connection, remote control, diagnosis and analysis, etc. The slave detection results can be summarized to the switchboard, and then sent to the cloud by the switchboard, thereby realizing multi-machine networking, master-slave connection, remote control, and remote diagnosis and analysis. When there are no bubbles in the hose colloid, that is, when no bubbles are detected, the ultrasonic waveform is as follows Figure 4 As shown; when there are bubbles with a diameter of more than 3mm in the hose colloid, the ultrasonic waveform is as follows Figure 4 As shown. Figure 4 and Figure 5 When the waveform amplitude is lower than the gate height (1.5V), the system outputs an alarm IO signal.

[0059] Matters not covered by the present invention are known technologies.

[0060] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting bubbles in a fluid (non-gas), characterized in that: The system used in the detection method is composed of multiple sets of ultrasonic probes, FPGA modules, Ethernet communication modules, switches, ultrasonic excitation / receiving modules, adjustable gain amplification modules, data acquisition modules, touch display modules, IO modules, PC hosts, peripheral hosts and cloud; Among them, the ultrasonic excitation / reception module can excite and receive multiple sets of ultrasonic probes; The specific detection method steps are as follows: 1) According to the acoustic attenuation coefficient of different fluids (non-gas) Determine the working frequency of the ultrasonic probe, reduce the attenuation of the ultrasonic sound pressure and sound intensity by the fluid, so that the ultrasonic detection sensitivity of this frequency meets the minimum detection bubble requirement, where η is the fluid viscosity coefficient and c is the ultrasonic sound velocity in the fluid; 2) Calculate the propagation path of a single set of ultrasonic probe beams in the pipe wall and fluid medium, Then determine the number of ultrasonic probe groups N, i.e. the number of channels, required for the ultrasonic beam to fully cover the fluid medium in the pipeline; Among them, α1 is the incident angle of the ultrasonic wave in the pipe wall, α2 is the refraction angle of the ultrasonic wave in the fluid medium, c1 is the sound speed of the ultrasonic wave in the pipe wall, and c2 is the sound speed of the ultrasonic wave in the fluid medium; 3) Determine the installation rotation angle between adjacent ultrasonic probe groups according to step 2) 4) According to the actual installation conditions, two methods can be used to fix the ultrasonic probe. One method is to mill the i-th group of ultrasonic probe installation planes at the i-th installation point of the pipeline. The other method is to add a semicircular sleeve at the i-th installation point of the pipeline and mill the i-th group of ultrasonic probe installation planes. 5) Debug the system and set the N-channel ultrasonic probe working mode, repetition frequency, fluid medium sound velocity, excitation voltage, pulse width, gain, translation, detection range, sampling rate, data compression ratio, filtering and other detection parameters through the PC host, peripheral host, cloud or FPGA module; 6) Use epoxy resin glue to fix the N-channel ultrasonic probe to the pipeline installation plane, fine-tune the probe to make it fit completely with the installation plane, and clamp it continuously for 24 hours under external force to allow the epoxy resin colloid to completely solidify; 7) After the epoxy resin colloid in step 6) is completely solidified, a sound-absorbing coating with a large acoustic impedance is sprayed on the circumferential area outside the ultrasonic probe installation plane at all detection points; 8) According to the minimum detection bubble requirement, use standard samples to calibrate the N channel and set the alarm threshold; 9) In the above steps, the system starts to detect bubbles in the fluid. When it is detected that the volume of bubbles exceeds the set alarm threshold (that is, the ultrasonic amplitude is lower than the alarm gate height), the system outputs an alarm IO signal to the outside; as a slave, the system supports multi-machine networking, master-slave connection, and cloud functions. The slave detection results can be summarized to the switchboard, and then sent to the cloud by the switchboard, thereby realizing remote control, remote diagnosis and analysis, fault prediction, and full life cycle prediction.

2. The method for detecting bubbles in a fluid (non-gas) according to claim 1, characterized in that: For different pipe diameters, the propagation path of the ultrasonic beam in the pipe wall and fluid medium is calculated, and the focal column diameter is calculated based on the focusing effect of the inner surface of the pipe on the ultrasonic beam of the selected frequency. Focal column length Reasonably plan the number of ultrasonic probe channels to fully cover the fluid medium in the pipeline, where λ is the ultrasonic wavelength, F is the focal length, and D is the chip diameter.

3. The method for detecting bubbles in a fluid (non-gas) according to claim 1, characterized in that: A sound-absorbing coating with high acoustic impedance is applied to the circumferential surface outside the cross section of the ultrasonic probe to eliminate multiple reflected waves other than the direct wave and improve the detection sensitivity.

4. The method for detecting bubbles in a fluid (non-gas) according to claim 1, characterized in that: The B / C scanning device can be connected externally through the IO module, and the trigger interval of the X-axis and Y-axis can be adjusted (0.1~2mm) to meet different detection accuracy requirements.

5. The method for detecting bubbles in a fluid (non-gas) according to claim 1, characterized in that: The ultrasonic excitation / receiving module can excite a multi-channel ultrasonic probe, and the pulse width of each channel ultrasonic probe is 20ns to 2.5us, with an increment of 2ns; the excitation voltage of each channel ultrasonic probe is 150 or 200 or 250V.

6. The method for detecting bubbles in a fluid (non-gas) according to claim 1, characterized in that: The adjustable gain amplifier module can receive multi-channel ultrasonic probe echo signals, and the gain of each channel is -20 to 60dB with an increment of 0.5dB; the gain is controlled by the FPGA module.

7. The method for detecting bubbles in a fluid (non-gas) according to claim 1, characterized in that: The data acquisition module is composed of multi-channel A / D acquisition units. The translation of each A / D acquisition unit is 0 to 65535 sampling points, and the detection range is 0 to 65535 sampling points.

8. The method for detecting bubbles in a fluid (non-gas) according to claim 7, characterized in that: The sampling rate of each channel of the multi-channel A / D acquisition unit is 125.00 or 62.50 or 25.00 or 5.00 MHz.

9. The method for detecting bubbles in a fluid (non-gas) according to claims 7 to 8, characterized in that: As a slave, the system compresses the multi-channel detection data according to the data compression ratio (1 to 10), and then transmits it to the PC host, peripheral host or cloud through the Ethernet communication module using the Ethernet TCP / IP protocol, thus solving the transmission bandwidth limitation and tracing the on-site detection data.

10. An application of the method described in any one of claims 1 to 9, for detecting bubbles in fluid (non-gas), realizing non-contact, high-beat, advanced detection, and being able to detect bubbles in advance, and then execute related operation processes to avoid blocking subsequent process flows. The system supports multi-machine networking, master-slave connection, and cloud functions, realizing remote control, remote diagnosis and analysis, fault prediction, and full life cycle prediction.

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