A distributed ultrasound transducer array and method of controlling the same

Abstract

The application provides a distributed ultrasonic transducer array and a control method thereof. The distributed ultrasonic transducer array comprises a plurality of unit ultrasonic transducers, the outer contour of the amplitude rod of each transducer is provided with a plurality of continuous cylindrical sections in the axial direction, each section is composed of a first cylindrical surface and a second cylindrical surface, the generatrix is a circular arc or a broken line symmetrical about the center line, and each cylindrical section forms an acoustic focal point with different radial distances in the medium. The plurality of transducers are arranged along the pipeline, and the focal domain distribution of adjacent transducers is arranged in the same or complementary mode, so that the radial focal domain of each transducer is spatially staggered and the energy is superposed, forming a synthesized sound field with small sound pressure fluctuation and uniform distribution. The application can realize large-range and high-uniformity cavitation treatment with fewer ultrasonic transducers, and can realize spatial differentiation regulation and control of focal energy according to the concentration distribution of pollutants, thereby significantly improving the treatment efficiency and engineering economy.

Description

Technical Field

[0001] This invention relates to a distributed ultrasonic transducer array and a control method for the distributed ultrasonic transducer array, belonging to the field of ultrasonic transducer technology. Background Technology

[0002] With increasingly stringent requirements for the treatment of new pollutants, key industries such as petrochemicals, pharmaceuticals, and dyeing are facing a growing demand for efficient treatment technologies for recalcitrant organic pollutants. Hydroxyl radicals (·OH), due to their strong oxidizing properties and lack of secondary residues, have become a core medium for advanced oxidation technologies. Ultrasonic cavitation, capable of inducing localized high temperatures and pressures in aqueous media, driving the pyrolysis of water molecules to generate hydroxyl radicals, has thus attracted widespread attention in the field of pollutant treatment. To achieve efficient cavitation treatment, it is typically necessary to focus the sound field of ultrasonic transducers to increase local energy density. However, the focusing area of ​​a single transducer is often limited, making it difficult to meet the treatment needs of large-scale contaminated sites or industrial operation areas. Therefore, ultrasonic transducer arrays have become an important technological approach.

[0003] Various ultrasonic transducer array configurations have been developed in existing technologies. For example... Figure 1 The matrix array and the ring coaxial distribution array shown expand the coverage area by arranging multiple transducers in a regular geometric pattern and using the spatial splicing of the fixed focal area of ​​each transducer. Figure 2 The diagram shows another common configuration where the radiating surfaces of three transducers are arranged in an equilateral triangle to form a combined sound field. However, this type of array design suffers from a common technical bottleneck: because the focal position and shape of a single transducer are pre-fixed by its structure and cannot be dynamically adjusted, it is difficult to achieve a smooth transition at the focal edges of adjacent transducers in the array. Sound pressure dips often occur at the junctions, resulting in severely uneven sound field energy distribution throughout the processing area and significant differences in local cavitation intensity, affecting the consistency of the processing effect. To compensate for the weak energy areas, it is usually necessary to further increase the number of transducers or increase the driving power, which not only significantly increases system cost and energy consumption but also introduces uncontrollable complex standing wave fields due to sound field interference between transducers, thus reducing overall cavitation efficiency.

[0004] Furthermore, in real-world pollution remediation scenarios, pollutant concentrations are often spatially non-uniformly distributed; for example, a significant concentration gradient exists at different depths or radial locations within a pollution plume. Existing array technologies can only provide a single, uniform acoustic field coverage mode, failing to adaptively adjust the energy weight or depth of the focal zone to accommodate differences in pollutant concentration. This results in incomplete treatment of high-concentration areas and energy waste in low-concentration areas, further hindering the engineering economics of ultrasonic cavitation technology.

[0005] Therefore, how to construct a synthetic sound field with a more uniform sound pressure distribution and higher energy utilization in a medium with fewer transducers, and how to spatially differentiate the energy of the focal region according to the characteristics of pollutant concentration distribution, is a long-standing but unsolved technical problem in this field. Summary of the Invention

[0006] The primary technical problem to be solved by this invention is to provide a distributed ultrasonic transducer array.

[0007] Another technical problem to be solved by the present invention is to provide a control method for a distributed ultrasonic transducer array.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: According to a first aspect of the present invention, a distributed ultrasonic transducer array is provided, comprising a plurality of ultrasonic transducers, each of the ultrasonic transducers comprising a transducer head, an amplitude transformer, and a connecting line; The transducer head is equipped with a piezoelectric ceramic crystal stack; The amplitude transformer is connected to the transducer head and is used to amplify the vibration displacement generated by the piezoelectric ceramic crystal stack. The connecting line is used to connect the ultrasonic transducer to the power amplifier module; The outer contour of the amplitude transformer includes multiple continuous cylindrical segments along the axial direction. Each cylindrical segment is formed by connecting a first cylindrical surface and a second cylindrical surface. The generatrices of the first cylindrical surface and the second cylindrical surface together form a circular arc or broken line symmetrical about the center line. The center line is perpendicular to the axis of the amplitude transformer, and each cylindrical segment forms an acoustic focus in the medium.

[0009] Preferably, the straight line perpendicular to the generatrix of the first cylindrical surface, the straight line perpendicular to the generatrix of the second cylindrical surface, and the center line intersect at a point, which is the sound focus formed by the cylindrical segment.

[0010] Preferably, the distance from the acoustic focal point to the axis of the amplitude transformer is different for each of the cylindrical segments.

[0011] Preferably, the radial distances from the acoustic focal points of each cylindrical segment of two adjacent ultrasonic transducers to their respective amplitude transformer axes are the same or complementary.

[0012] Preferably, the ultrasonic transducer operates in the frequency range of 20kHz to 100kHz.

[0013] Preferably, the distributed ultrasonic transducer array further includes a sensor positioned at a location capable of detecting spectral data of the region of maximum light flux generated by the ultrasonic transducer in the medium that induces cavitation bubbles.

[0014] According to a second aspect of the present invention, a control method for the above-described distributed ultrasonic transducer array is provided, comprising the following steps: Step 1: The signal generator receives the start signal and performs initial configuration of the drive frequency of each ultrasonic transducer; Step 2: Each ultrasonic transducer operates at the initially configured frequency, and the fiber optic probe collects the optical signal generated when cavitation bubbles collapse in the aqueous phase of the medium. Step 3: The spectrum analyzer receives the optical signal and decomposes it into a spectrum, extracts the integrated intensity of the ultraviolet band as the luminous intensity; changes the driving frequency with a set step size within a preset frequency range, records the luminous intensity corresponding to each frequency point, and determines the frequency corresponding to the maximum luminous intensity as the optimal frequency. Step 4: The signal generator fixes the driving frequency of each ultrasonic transducer to the optimal frequency, increases the output voltage amplitude step by step according to the set step size, and monitors the light intensity in real time, adjusting the output voltage until the light intensity reaches the maximum value under the current conditions.

[0015] Preferably, in step 1, the driving frequency of the ultrasonic transducer is initialized to the lowest frequency that causes cavitation in the aqueous phase of the medium and is acceptable for formation disturbance.

[0016] Preferably, the spectrum analyzer decomposes the optical signal into a spectrum and extracts the integrated intensity in the ultraviolet band as the emitted light intensity.

[0017] Preferably, the emitted light intensity is the integrated intensity of the ultraviolet band in the optical signal collected when the fiber optic probe is located in the maximum optical flux region.

[0018] Preferably, step 3 includes the following sub-steps: Step 31: Record the input voltage, current, power density and light intensity at the current driving frequency, and determine whether the light intensity is greater than or equal to the preset light intensity threshold. If so, proceed directly to step 4. Step 32: Under the control of the electronic control system, the command signal generator gradually changes the driving frequency within the preset frequency range with a constant output voltage amplitude and a set frequency step size. At each frequency point, the input active power and the corresponding light intensity are recorded, and the light intensity is plotted as a function of frequency. The frequency corresponding to the peak point of the curve is determined as the optimal frequency.

[0019] Preferably, the power density of the ultrasonic transducer is controlled in a range where the slope of the power density-luminous intensity relationship curve of the medium is greater than a preset threshold.

[0020] Preferably, the control method further includes: Step 5: The fiber optic probe detects the emitted light intensity again to determine whether it has reached the expected intensity value. If it has, the current parameters are maintained and the operation continues. If it has not, automatic frequency tracking is started, and a micro-frequency scan is performed within the set frequency window with the optimal frequency as the center. The driving frequency is adjusted in real time to restore the emitted light intensity to the maximum value. Step 6: When the continuous working time reaches the expected duration, the process ends.

[0021] According to a third aspect of the present invention, an acoustic luminescence radical generation system employing the above-described distributed ultrasonic transducer array is provided, comprising an electronic control system, a signal generator, a spectrum analyzer, an oscilloscope, a power amplifier module, an optical fiber probe, and a preamplifier; The electronic control system is connected to the signal generator and the spectrum analyzer via a bus, respectively. The output of the signal generator is connected to the ultrasonic transducer via the power amplification module to drive the ultrasonic transducer to generate an ultrasonic cavitation effect in the medium. The fiber optic probe is used to collect the optical signal generated when cavitation bubbles collapse, and its output is connected to the oscilloscope and the spectrum analyzer via the preamplifier. The spectral analysis results output by the spectrum analyzer are transmitted to the electronic control system as a feedback signal, and the electronic control system adjusts the output parameters of the signal generator according to the feedback signal. The medium is optically opaque or has strong light absorption properties, or distorts the light propagation path, or has physical obstacles to light propagation, and the medium contains an aqueous phase that can participate in the reaction.

[0022] Preferably, the acoustic luminescence radical generation system further includes an adaptive frequency tracking circuit module, which includes a microcontroller, a pulse generator, a power amplifier module, a matching network, a current detection module, and an A / D conversion module. The microcontroller controls the pulse generator to generate an electrical pulse signal. The electrical pulse signal is amplified in voltage and power by the power amplification module and then transmitted to the ultrasonic transducer via the matching network. The current detection module collects the operating current of the power amplifier module in real time and converts it into an analog signal. The A / D conversion module converts the analog signal into a digital signal and feeds it back to the microcontroller.

[0023] Preferably, the axis of the fiber optic probe is aligned with or parallel to the axis of the radiating surface of the ultrasonic transducer.

[0024] Compared with existing technologies, this invention constructs a distributed array of ultrasonic transducers with multi-segment irregularly shaped curved amplitude transformers. Each transducer's amplitude transformer outer contour forms multiple acoustic focal points with varying radial distances along the axial direction, thus creating a surrounding three-dimensional focal zone around each transducer. Furthermore, by setting the focal zone distribution of adjacent transducers to the same or complementary patterns, the radial focal zones of each transducer spatially interweave and superimpose energy. Without increasing the number of transducers, this synthesizes a sound field with smaller sound pressure fluctuations and more uniform energy distribution within the target area, effectively eliminating sound pressure troughs and energy gaps at the junctions of conventional arrays. Simultaneously, this distributed ultrasonic transducer array can select transducer combinations with different focal zone distributions based on the spatial concentration gradient of the pollution plume, achieving enhanced energy coverage of high-concentration areas and balanced treatment of low-concentration areas. This spatially differentiated sound field layout can be achieved without mechanical scanning or dynamic phase modulation. While significantly reducing system complexity and manufacturing costs, it greatly improves the consistency of cavitation treatment, energy utilization efficiency, and pollutant removal effect in large-scale operating scenarios. Attached Figure Description

[0025] Figure 1 This is a schematic photograph of the structure of the first ultrasonic transducer array in the prior art; Figure 2 This is a schematic diagram of the structure of the second type of ultrasonic transducer array in the prior art; Figure 3A This is a schematic diagram of the structure of the ultrasonic transducer provided in the first embodiment of the present invention; Figure 3B for Figure 3A The image shown is a photograph of the actual ultrasonic transducer. Figure 3C for Figure 3A An enlarged schematic diagram of an amplitude transformer in the ultrasonic transducer shown; Figure 3D for Figure 3A An enlarged schematic diagram of an amplitude transformer in the ultrasonic transducer shown; Figure 3E for Figure 3A An enlarged schematic diagram of an amplitude transformer in the ultrasonic transducer shown. Figure 4 This is a schematic diagram illustrating the application of a distributed ultrasonic transducer array provided in an embodiment of the present invention in a pollutant treatment application scenario. Figure 5A This is a schematic diagram of the focal position of an ultrasonic transducer in the first embodiment of the present invention; Figure 5B This is a schematic diagram of another focal position of the ultrasonic transducer in the first embodiment of the present invention; Figure 5CThis is a schematic diagram of one arrangement of a distributed ultrasonic transducer array in the first embodiment of the present invention; Figure 5D This is a schematic diagram of another arrangement of the distributed ultrasonic transducer array in the first embodiment of the present invention; Figure 6 This is an overall structural block diagram of the sonoluminescence radical generation system provided in the second embodiment of the present invention; Figure 7 This is a schematic diagram of an adaptive frequency tracking circuit module for an ultrasonic transducer in the second embodiment of the present invention. Figure 8 The graph shows the relationship between the electrical power density of the ultrasonic transducer and the luminous intensity of cavitation bubbles in pure water. Detailed Implementation

[0026] The technical content of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0027] In one embodiment of the present invention, the technical concept is to construct a distributed array of multiple ultrasonic transducers with multi-segment irregular curved amplitude rods. The outer contour of the amplitude rod of each transducer forms several acoustic focal points with a gradient radial distance along the axial direction, thereby constructing a surround three-dimensional focal zone around a single transducer. Based on this, by setting the focal zone distribution of adjacent transducers to the same or complementary mode, the acoustic focal points of each transducer arranged radially are spatially interlaced and superimposed with energy. Without increasing the number of transducers or requiring mechanical scanning or dynamic phase modulation, a synthesized sound field with smaller sound pressure fluctuations and more uniform energy distribution is synthesized in the target area, effectively eliminating the sound pressure troughs and energy gaps at the splicing points of conventional arrays. At the same time, this distributed array can achieve differentiated sound field layouts by selecting transducer combinations with different focal zone distributions according to the spatial concentration gradient of the pollution plume, thereby achieving synergistic improvement in treatment consistency, energy utilization efficiency, and engineering economy in large-scale contaminated site remediation and industrial operation scenarios with fewer transducers and lower system complexity.

[0028] First Embodiment like Figures 3A to 3DAs shown, this embodiment of the invention first provides a unit-type ultrasonic transducer 10, including a transducer head 11, an amplitude transformer 12, and a connecting line 13. The transducer head 11 adopts a sandwich-type piezoelectric ultrasonic transducer structure, with a piezoelectric ceramic crystal stack 111 inside. This crystal stack is clamped and fixed by a front cover plate 112 and a rear cover plate 113, and is fastened together by prestressed bolts. The outer shells of both the transducer head 11 and the amplitude transformer 12 are made of stainless steel (such as 304 or 316). A flange 116 is provided between the end face of the transducer head 11 and the amplitude transformer 12, and the two are fastened together by bolts. The amplitude transformer 12 is used to mechanically amplify the small vibration displacement generated by the piezoelectric ceramic crystal stack 111 to increase the emitted sound pressure, while also amplifying the sound wave and facilitating sound field focusing. The connecting line 13 is used to connect the ultrasonic transducer 10 to a power amplification module. A sensor 14 is also fixed on the flange 116. In one embodiment of the present invention, the sensor 14 can be implemented as an optical fiber probe, with one end fixed to the flange 116 and the other end extending parallel to the axis 100 of the amplitude rod 12 to the working end face 120 of the amplitude rod 12.

[0029] In one embodiment of the present invention, the operating frequency range of the ultrasonic transducer 10 is preferably 20kHz to 100kHz, which falls within the category of low-frequency transducers. This frequency band is selected based on the following technical considerations: too low a frequency will result in excessively large cavitation bubbles, significantly increasing ground disturbance; too high a frequency will result in excessively small cavitation bubbles, reducing ground penetration and shrinking the effective operating area. The specific frequency range of the transducer and the pressure-bearing capacity of its casing need to be determined according to actual working conditions (such as the soil or geological characteristics of the pollution plume).

[0030] like Figure 3C As shown, the outer contour of the amplitude transformer 12 is composed of multiple continuous cylindrical segments along the axial direction, each segment having a different cross-sectional area. Each cylindrical segment is formed by connecting a first cylindrical surface 121 and a second cylindrical surface 122. Figure 3C In the illustrated embodiment, the outer contours of both the first cylindrical surface 121 and the second cylindrical surface 122 are conical surfaces, and the cross-sectional diameter at their junction is the smallest. Figure 3D In the embodiment shown, the generatrices of the first cylindrical surface 121 and the second cylindrical surface 122 are arcs with the same curvature, and the cross-sectional diameter at the junction of the two is also the smallest. Figure 3E and Figure 3D Similarly, the difference lies in the way adjacent cylindrical segments are connected: Figure 3E Adjacent segments are connected by cylinders of equal diameter.

[0031] Regardless of the outer contour shape, in each cylindrical segment of the amplitude transformer 12, the generatrices of the first cylindrical surface 121 and the second cylindrical surface 122 together form a circular arc (with the same curvature) or a broken line symmetrical about the center line, and this center line is perpendicular to the axis 100 of the amplitude transformer 12. For example... Figure 3CAs shown by the dashed line, in the first and fourth segments, the generatrices of the first cylindrical surface 121 and the second cylindrical surface 122 are both symmetrical broken lines, and the line of symmetry of these broken lines is perpendicular to the axis 100. The straight line perpendicular to the generatrice of the first cylindrical surface 121, the straight line perpendicular to the generatrice of the second cylindrical surface 122, and the aforementioned center line intersect at a point, which is the acoustic focal point formed by this cylindrical segment; the three-dimensional spatial distribution region of the high-intensity sound field near the acoustic focal point is defined as the focal region.

[0032] In different implementation schemes, the radial distance between the acoustic focal point corresponding to each cylindrical segment and the axis 100 of the amplitude transformer can be set differently. For example... Figure 3C and Figure 3D As shown, the acoustic focal point formed by the first cylindrical surface 121 and the second cylindrical surface 122 in the first segment and the acoustic focal point formed by the first cylindrical surface 121A and the second cylindrical surface 122A in the third segment have significantly different vertical distances from the axis 100.

[0033] Through the optimized design of the above-mentioned busbar shape, the amplitude transformer 12 can not only propagate and focus sound waves along the axial direction (i.e., focus the sound field on the radiating surface), but also form multiple discrete or continuous sound wave energy accumulation regions, i.e., focal zones, in the radial direction. These radial focal zones are arranged along the axial direction of the amplitude transformer and are interconnected, forming an annular columnar sound field enhancement zone surrounding the amplitude transformer 12. This design enables the ultrasonic transducer 10 to simultaneously form a high-intensity, controllable sound field in front of the radiating surface and in the medium surrounding the amplitude transformer, thereby achieving large-scale, homogenized treatment of the medium surrounding the transducer. Compared with conventional technologies that can only obtain a single axial sound focus in front of the radiating surface, this invention adopts a composite vibration mode design. Through the coordinated control of the amplitude transformer cross-sectional profile and resonant frequency, longitudinal vibration and radial resonance are simultaneously excited, forming a surrounding sound pressure enhancement zone around the amplitude transformer body based on axial amplitude amplification.

[0034] The length of the amplitude transformer 12 can be selected from 0.2m to 3m, preferably 0.5m to 2m, and more preferably 1m to 1.5m. Under the same input power conditions, increasing the length of the amplitude transformer will lead to a decrease in the energy density per unit area of ​​the working surface; however, since the ultrasonic transducer 10 provided by the present invention incorporates the radial focal zone into the effective working area, rather than relying solely on the axial focal zone directly in front of the radiating surface, even if the length of the amplitude transformer is increased, its processing efficiency and effect per unit cycle will not be significantly reduced. On the contrary, in application scenarios requiring large-scale operations, such as contaminated site remediation, a longer amplitude transformer can reduce the number of boreholes and the frequency of transducer relocation, thereby reducing engineering costs and operation time; with a corresponding increase in input power, the length of the amplitude transformer also helps to increase the number of focal zones and the coverage volume, improving the processing capacity per single working cycle.

[0035] The acoustic field intensity distribution excited by the radiating surface of a conventional amplitude transformer is usually relatively uniform, lacking effective focusing capability. This makes it difficult to form a sufficiently dense and controllable cavitation region in the medium under industrially feasible power conditions, thus limiting the engineering application of the high-temperature and high-pressure effects generated by cavitation bubble collapse. In contrast, this invention employs a specific curved surface design for the radiating surface and cylindrical section profile of the amplitude transformer 12, enabling it to form one or more high-intensity focal zones in the radial annular region of the amplitude transformer within the medium. This design highly concentrates ultrasonic energy within these focal zones, thereby inducing dense cavitation clouds more efficiently and controllably in the medium, and significantly enhancing the localized high temperature and high pressure generated during cavitation bubble collapse, along with the accompanying strong physicochemical effects (including water molecule pyrolysis and the breaking of chemical bonds in organic pollutant molecules).

[0036] Furthermore, this embodiment of the invention selects a low-frequency transducer in the 20kHz–100kHz band, which is beneficial for enhancing the aforementioned physicochemical effects. The mechanism is as follows: the sound pressure threshold for cavitation decreases with decreasing frequency; that is, under the same sound power input conditions, low-frequency sound waves are more likely to induce cavitation in the medium, thereby achieving a higher cavitation bubble density. Simultaneously, the positive pressure phase provided by low-frequency sound waves lasts longer, allowing cavitation bubbles more sufficient growth time to reach a larger maximum radius. Larger-radius bubbles possess stronger inertial kinetic energy at the moment of collapse, enabling more violent implosion, higher local temperature and pressure, thereby significantly promoting the pyrolysis of water molecules and the breaking of molecular chains of organic pollutants.

[0037] Multiple of the above-mentioned unit-type ultrasonic transducers 10 constitute the distributed ultrasonic transducer array provided in the first embodiment of the present invention. For example... Figure 4 As shown, the transducer heads 11 of each ultrasonic transducer are arranged along the same pipeline, and their amplitude transformers 12 are perpendicular to the pipeline. When the pipeline is straight, each transducer head 11 is located on the straight line, and each amplitude transformer 12 is perpendicular to the pipeline; when the pipeline is not straight, each transducer head 11 is located on the pipeline, and each amplitude transformer 12 is arranged radially with the pipeline as the center.

[0038] like Figure 5A and Figure 5B As shown, combined with Figure 3C When a single ultrasonic transducer 10 moves along its axis 100, the acoustic focus formed by the first cylindrical section (with a relatively large radial distance, such as...) Figure 5A The acoustic focal point formed by the middle F1 and the third cylindrical surface (with a small radial distance, such as...) Figure 5A As shown in F2, the vertical distances from the axis 100 are different, and during the movement, the focal areas connect spatially to form a continuous ring-shaped processing area. Partial overlap can occur between the focal areas (e.g., ...). Figure 5A As shown in F3), they can also be separated from each other (as shown in F3). Figure 5B (As shown).

[0039] exist Figure 5A In the scheme shown, focal zones F1 and F2 partially overlap in the radial direction, forming an overlapping region F3. The medium within this overlapping region experiences acoustic radiation from different focal zones sequentially (e.g., first radiation from the third focal zone, then radiation from the first focal zone), resulting in a higher cumulative acoustic energy than the region subjected to radiation from only a single focal zone. This achieves more uniform and higher-intensity treatment of the medium surrounding the amplitude transformer 12.

[0040] Furthermore, such as Figure 5C As shown, the focal domain distribution of two adjacent ultrasonic transducers in this distributed ultrasonic transducer array can be configured as a complementary mode. For example, the radial distance from the acoustic focal point of each cylindrical segment of one ultrasonic transducer to its amplitude transformer axis gradually decreases from the radiating surface to flange 116, while the corresponding radial distance of the other ultrasonic transducer gradually increases. When the pair of transducers are arranged parallel to each other in the pollution plume region, a synthetic sound field with uniform sound pressure distribution is formed between them (e.g., Figure 5C (As shown in the dashed area), this is suitable for treatment conditions where the pollutant concentration is uniformly distributed.

[0041] like Figure 5D As shown, the focal distribution of two adjacent ultrasonic transducers can also be set in the same pattern, that is, the acoustic focal points with the largest radial distance (such as focal point 1) are arranged at the same axial depth. This arrangement can form an energy enhancement zone in a specific depth region (such as...). Figure 5D (As shown in the dashed area), this applies to working conditions where pollutant concentrations are distributed in layers and require differentiated treatment.

[0042] It should be noted that in the distributed ultrasonic transducer array provided in this embodiment of the invention, the radial distances from the acoustic focal point of each cylindrical segment of each transducer to the axis of the amplitude transformer are gradient-distributed (i.e., different distances). This design facilitates the spatial overlapping of the focal regions of adjacent transducers, thereby obtaining a more uniform synthetic sound field. This differs from the conventional unitary transducer technique, which allows equal or adjustable radial distances, and is the basis for achieving spatial energy complementarity in this distributed ultrasonic transducer array.

[0043] In summary, the distributed ultrasonic transducer array provided in this embodiment of the invention can flexibly select the focal zone combination method according to the spatial concentration distribution characteristics of the pollution plume, and achieve efficient and targeted treatment of non-uniform pollution areas without the need for frequent transducer movement or increasing the number of transducers, significantly saving operation time and engineering costs.

[0044] Second Embodiment like Figure 4 and Figure 6As shown, the second embodiment of the present invention provides a sonoluminescence radical generation system, wherein the distributed ultrasonic transducer array in the first embodiment is used. In one embodiment of the present invention, the sonoluminescence radical generation system includes a signal generator, a spectrum analyzer, and an oscilloscope, which are centrally controlled by an electronic control system. The electronic control system is connected to and centrally controls the signal generator and the spectrum analyzer via a GPIB bus. The electrical signal output by the signal generator is amplified by a power amplifier module and drives the ultrasonic transducer 10 to generate an ultrasonic cavitation effect in the medium. The light signal generated during the cavitation process is collected by a sensor 14, amplified by a preamplifier, and then sent to the oscilloscope for real-time waveform display (the oscilloscope also communicates with the electronic control system via a GPIB bus), and to the spectrum analyzer for spectrum analysis, thereby realizing closed-loop control of the entire process of ultrasonic cavitation luminescence phenomenon from excitation and acquisition to signal analysis.

[0045] like Figure 6 As shown, the spectrum analyzer, preamplifier, electrical control system, oscilloscope, signal generator, and power amplifier module are all located on the ground far away from the pollution plume, while multiple ultrasonic transducers 10 and sensors 14 are installed in the underground medium where the pollution plume is located. The signal connection lines and power lines between the devices are laid in the pipeline to realize the electrical connection between the ground and the underground.

[0046] In one embodiment of the present invention, the ultrasonic transducer 10 is connected to an adaptive frequency tracking circuit module. For example... Figure 7 As shown, this module includes a drive circuit consisting of a microcontroller, a pulse generator, a power amplifier module, a matching network, and a transducer, as well as a feedback circuit consisting of a current detection module and an A / D conversion module. The current detection module is connected to the drive circuit to collect the operating current flowing through the transducer in real time. The A / D conversion module converts the detected analog current signal into a digital signal and transmits it to the microcontroller. The microcontroller has a built-in frequency modulation algorithm that analyzes the received digital current signal and outputs a frequency adjustment command to the pulse generator, gradually adjusting the pulse signal frequency to ensure the transducer always operates in a resonant state with the maximum current. This drive signal is amplified by the power amplifier module and impedance matched by the matching network before finally driving the transducer.

[0047] The microcontroller also integrates a motion module for controlling the axial movement of a single ultrasonic transducer 10. The motion module determines whether movement is necessary and the movement step size based on feedback signals. The movement step size is measured in units of the length of each cylindrical segment of the amplitude transformer 12. In applications involving porous solid media (such as contaminated soil), segmented treatment of contaminated areas at different depths is achieved by moving the amplitude transformer 12 of the ultrasonic transducer 10 within the borehole. The motion module drives a telescopic mechanism to move the ultrasonic transducer 10 to a first position and begins timing. When the first treatment time ends, the telescopic mechanism moves the ultrasonic transducer 10 to a second position and restarts timing. This process is repeated until the ultrasonic transducer 10 is gradually withdrawn from the deepest part of the borehole to beyond the boundary of the contamination plume, completing the treatment operation across the entire depth range.

[0048] Through the above closed-loop control, the adaptive frequency tracking circuit module can automatically track the resonant frequency drift of the ultrasonic transducer 10 caused by factors such as temperature changes and load fluctuations during operation, ensuring that the transducer always operates in the optimal resonant state, thereby ensuring the stability of the sound field output and the efficiency of electro-acoustic energy conversion.

[0049] The temperature at the collapse center of a single bubble can be estimated by measuring the sonoluminescence spectrum of cavitation bubbles, and the free radical production is strongly positively correlated with this temperature. However, spectrothermography requires the measurement object to be a stable, periodically collapsing single bubble, and the medium must be optically transparent. In practical applications such as underground soil, the opacity of the medium prevents light from propagating effectively. Furthermore, the focused sound field of this invention excites a multi-bubble cavitation mode, so conventional spectrothermography cannot obtain clear inert gas spectral lines for temperature estimation. To address this technical bottleneck, this embodiment of the invention uses sensor 14 to directly detect the emission intensity, replacing the single-bubble collapse temperature as a feedback control variable to adjust the pulse generator drive frequency (keeping the ultrasonic transducer 10 in a resonant state that generates maximum emission intensity), thereby ensuring the continuous and stable generation of cavitation bubbles. The physical basis for this is that the emission intensity is directly related to the intensity of cavitation bubble collapse; the stronger the intensity, the higher the local temperature and pressure at the moment of collapse, and the greater the amount of free radicals generated. Therefore, emission intensity is the most direct and suitable optical tracer index for engineering applications to characterize cavitation intensity.

[0050] like Figure 4 As shown, both sensor 14 and ultrasonic transducer 10 are inserted into the medium to be treated (e.g., soil or water to be remediated), and they are arranged coaxially. Alternatively, sensor 14 can also be fixed to flange 116 of ultrasonic transducer 10 (see [reference]). Figure 3EThe sensor 14 is deployed along with the transducer in a pre-drilled well in the soil (e.g., 10–20 meters underground depending on the depth of the pollution plume). By adjusting the relative distance between the end face of the sensor 14 and the radiating surface of the ultrasonic transducer 10, spectral data of the maximum luminous flux region can be accurately captured, thereby obtaining the emission intensity in the ultraviolet band.

[0051] It should be noted that sensor 14 can also be replaced by other types of photoelectric sensors, such as a high-speed camera (with an image intensifier) ​​directly capturing the luminescence process of cavitation bubbles. Furthermore, since cavitation bubbles not only generate light signals when they collapse, but also radiate high-frequency acoustic pulses with characteristic frequencies, acoustic sensors can also be used to monitor cavitation intensity. All of the above alternative solutions fall within the scope of equivalent embodiments of this invention, requiring only the direct or indirect detection (such as light intensity, sound intensity, etc.) of the cavitation intensity induced by the ultrasonic transducer 10, and the use of this detection to control the operating parameters of the ultrasonic transducer 10.

[0052] Third Embodiment A third embodiment of the present invention provides a control method for the aforementioned distributed ultrasonic transducer array. This control method is applicable to the distributed ultrasonic transducer array described in the first embodiment and the acoustic luminescence radical generation system described in the second embodiment, and can be applied to various scenarios such as pollutant treatment and industrial cleaning. In one embodiment of the present invention, the control method specifically includes the following steps.

[0053] Step 1: Initial Configuration After receiving the start signal, the signal generator initially configures the driving frequency of each ultrasonic transducer 10 in the distributed ultrasonic transducer array. The initial frequency is preferably set to the lowest frequency that causes cavitation in the aqueous phase of the medium and is acceptable for formation disturbance, typically 20 kHz; alternatively, it can also scan from high frequency (e.g., 100 kHz) to low frequency until the sensor 14 detects the acoustic luminescence signal.

[0054] Step 2: Cavitation Excitation and Optical Signal Acquisition Each ultrasonic transducer 10 operates at the initially configured frequency to excite cavitation bubbles in the aqueous phase of the medium; the sensor 14 is set in the maximum light flux region to collect and output the light signal generated when the cavitation bubbles collapse.

[0055] Step 3: Optimal Frequency Identification The spectrum analyzer receives the optical signal output by sensor 14, decomposes it into a spectrum, and extracts the integrated intensity of the ultraviolet band (200-400nm) as the emitted light intensity. The real-time emitted light intensity is compared with a preset light intensity threshold; if the threshold is not reached, a frequency parameterization scan is initiated.

[0056] The frequency scanning process is as follows: Keeping the output voltage amplitude and pulse width of the signal generator constant, the driving frequency is gradually changed in steps (e.g., 100Hz) near the initial frequency. The luminous intensity corresponding to each frequency point is recorded, and a luminous intensity-frequency curve is plotted. The frequency corresponding to the peak point of this curve is the optimal frequency under the current conditions. This process ensures the highest electro-acoustic conversion efficiency, thereby obtaining the strongest cavitation effect and luminous intensity at a safe power density. Figure 8 The relationship between electric power density and light intensity at different frequencies in pure water is given. Similar curves can be obtained in specific media.

[0057] In one embodiment of the present invention, step 3 further includes the following sub-steps: Step 31: Initial State Diagnosis Record the input voltage, current, power density and light intensity at the current driving frequency, and determine whether the light intensity is greater than or equal to the preset light intensity threshold; if yes, proceed directly to step 4; if no, proceed to step 32.

[0058] Step 32: Frequency Scanning and Optimal Frequency Locking Centered on the nominal resonant frequency of the ultrasonic transducer 10, a scanning range (e.g., ±1kHz) is set, with the system resolution (e.g., 1–5Hz) as the frequency step. Under the control of the electronic control system, the command signal generator gradually changes the driving frequency with a constant output voltage amplitude. At each frequency point, the input active power and the corresponding luminous intensity are recorded using a power meter or oscilloscope. A curve of luminous intensity versus frequency is plotted, and the frequency corresponding to the peak point of the curve is determined as the optimal frequency.

[0059] Step 4: Power Optimization The signal generator fixes the driving frequency of each ultrasonic transducer 10 to the optimal frequency determined in step 3, and gradually increases the output voltage amplitude in preset steps. Simultaneously, it monitors the emitted light intensity in real time and dynamically adjusts the output voltage until the emitted light intensity reaches its maximum value under the current conditions. Preferably, the power density of the ultrasonic transducer 10 is controlled within the power density-emitted light intensity relationship curve for a specific medium (e.g., ...). Figure 8 The section with energy amplification effect (i.e., the section where the slope of the curve increases significantly) is shown in the figure to achieve the engineering goal of low power consumption and high output.

[0060] Step 5: Frequency Tracking and Drift Compensation Sensor 14 detects the emitted light intensity again to determine whether the expected intensity value has been reached. If it has been reached, the current parameters are maintained and operation continues; if it has not been reached, automatic frequency tracking is initiated: with the optimal frequency as the center, a small scanning window (e.g., ±5Hz) is set, and a small-amplitude frequency scan is performed at a relatively long time interval (e.g., per second). An extreme value search algorithm (e.g., perturbation observation method) is used to adjust the driving frequency in real time so that the emitted light intensity is always maintained at the maximum value, thereby compensating for the resonant frequency drift caused by transducer heating, load changes, etc.

[0061] Step 6: Process Termination The process ends when the continuous working time reaches the expected duration. The expected duration can be preset based on the results of plume simulation calculations or process requirements.

[0062] For large-scale or multi-region processing scenarios, the focal position can be changed by adjusting the phase of the distributed ultrasonic transducer array. Steps 3 to 5 are repeated until the entire target area is processed.

[0063] Taking in-situ soil remediation as an example: After completing the spatial positioning of the pollution plume, each ultrasonic transducer 10 and its corresponding sensor 14 in the distributed ultrasonic transducer array are lowered to the target depth in the well, and steps 1 to 6 are executed; during the remediation process, the driving frequency and power are dynamically adjusted based on the real-time light intensity feedback, and the pressure and temperature in the well are monitored simultaneously; after the current area is treated, each ultrasonic transducer 10 is driven to move along the axis to the next working depth or position through the moving module, and the above steps are repeated to gradually complete the remediation operation of the entire area.

[0064] It should be noted that the specific values ​​involved in the above steps (such as 20kHz, 100Hz, ±1kHz, ±5Hz, etc.) are exemplary parameters of the embodiments of the present invention and do not constitute a limitation on the scope of protection. Those skilled in the art can make adaptive adjustments according to actual operating conditions, transducer specifications, and medium characteristics.

[0065] Fourth embodiment In the fourth embodiment of this invention, the aforementioned sonoluminescent radical generation system not only generates hydroxyl radicals through the pyrolysis of water molecules, but the high-temperature and high-pressure environment generated by the instantaneous collapse of cavitation bubbles also possesses sufficient energy density to directly act on organic pollutant molecules, causing the carbon chains of hydrocarbon macromolecules to break and functional groups to decompose, generating small molecule intermediates and gradually mineralizing them. Based on this mechanism, this invention can be widely applied to various organic pollutant treatment scenarios, covering the following hydrocarbon and derivative categories. The compounds and pollution sources listed in each example are representative cases and do not constitute a limitation on the scope of application.

[0066] Aromatic hydrocarbons include benzene, toluene, ethylbenzene, xylene, and phenol. They are used in industries such as petrochemicals, oil refining, coatings, pharmaceuticals, printing, rubber and plastics, and solvent production. This invention can be applied to soil and groundwater in petrochemical plant areas, wastewater discharge sites in chemical industrial parks, underground oil tank areas at gas stations, areas surrounding coking plants and refineries, coating and solvent production workshops, solvent-using sites in printing, painting, and shoemaking, and wastewater areas in pharmaceutical and pesticide production.

[0067] Polycyclic aromatic hydrocarbons (PAHs) include naphthalene, phenanthrene, anthracene, and pyrene. They are involved in industries such as coking, coal chemical industry, asphalt production, thermal power, steel smelting, and waste incineration. This invention can be applied to coal coking plants and tar processing plants, former gas plant sites, asphalt paving and storage areas, petroleum refining residue areas, soil surrounding waste incineration plants, and contaminated sites surrounding thermal power plants.

[0068] Alkanes: including methane, ethane, propane, n-hexane, diesel alkanes, etc. This invention relates to industries such as oil extraction, natural gas industry, oil refining, oil storage and transportation, and gas stations. It can be applied to oil extraction and pipeline leak areas, contaminated gas station sites, oil fields and shale gas fields, natural gas storage and transportation systems, and contaminated oil depot areas.

[0069] Olefins: including ethylene, propylene, styrene, etc. This invention relates to industries such as petrochemicals, plastics manufacturing, synthetic rubber, and resin production. It can be applied to petrochemical cracking units, plastics and rubber manufacturing plants, polyethylene / polypropylene production areas, and synthetic resin and foam material factories.

[0070] Alkynes: including acetylene, propyne, etc. This invention relates to industries such as welding, gas production, calcium carbide chemicals, and metal processing. It can be applied to welding and metal processing plants, chemical synthesis gas production facilities, calcium carbide plants, and gas storage and transportation stations.

[0071] Halogenated hydrocarbons: including trichloroethylene, tetrachloroethylene, chloroform, brominated hydrocarbons, fluorinated hydrocarbons, etc. These are applicable to industries such as electronics manufacturing, metal cleaning, dry cleaning, refrigeration equipment, and pharmaceuticals and chemicals. This invention can be applied to electronic component cleaning plants, metal degreasing and cleaning workshops, dry cleaning shops and former dry cleaning plant sites, refrigerant production and repair areas, and semiconductor industrial zones.

[0072] Halogenated aromatic hydrocarbons: including chlorobenzene, dichlorobenzene, polychlorinated biphenyls, etc. These are involved in industries such as pesticide production, power equipment manufacturing, chemical dyes, and insulating materials. This invention can be applied to sites of insulating oil leaks and pesticide and dye production plants.

[0073] Petroleum hydrocarbons: including crude oil, diesel oil, lubricating oil, etc. This invention relates to industries such as oil extraction, refining, oil storage and transportation, transportation, and machinery manufacturing. It can be applied to oil fields and production platforms, refineries and oil storage tank areas, machine shops, and areas prone to pipeline leaks.

[0074] Heavy organic hydrocarbons, including asphalt and coal tar, are involved in industries such as coking, coal chemical industry, road asphalt, and waterproofing material production. This invention can be applied to former coking plant sites, gas plant ruins, and road asphalt production plants.

[0075] Pesticide-related organic hydrocarbons: including organochlorine pesticides, etc. This involves industries such as pesticide manufacturing, agricultural planting, and pest control storage. This invention can be applied to areas of farmland historically used with pesticides and contaminated areas at former pesticide factory sites.

[0076] Heteroatom-containing organic hydrocarbons: including oxygen / nitrogen-containing aromatic hydrocarbons (such as phenols and anilines). This invention relates to industries such as dye manufacturing, pharmaceutical manufacturing, fine chemicals, explosives and military industries, and rubber industries. It can be applied to dye factories, pharmaceutical and fine chemical plants, explosives and military factories, leather processing plants, and rubber industrial zones.

[0077] The above examples are merely partial illustrations of the application of the technical solutions of this invention in the field of organic pollutant treatment, and are not exhaustive enumeration of application scenarios. Any medium environment in which the sonoluminescence radical generation system provided by this invention can generate cavitation effects and induce chemical bond breaking should be considered within the scope of protection of this invention.

[0078] Fifth Embodiment In the fifth embodiment of this invention, the aforementioned sonoluminescent radical generation system, through the photolysis and / or high-temperature and high-pressure effects generated instantaneously by the collapse of cavitation bubbles, can not only pyrolyze water molecules to generate hydroxyl radicals, but also directly act on organic pollutant molecules, causing the breakage of multiple covalent bonds in the carbon center, generating corresponding radical intermediates and gradually mineralizing them. The following are examples of the types of covalent bonds that can be broken by this system and their typical application scenarios. The compounds and industries listed are representative illustrations and do not constitute a limitation on the scope of protection: CC bonds (alkane and petroleum hydrocarbon backbone): involved in the petrochemical and energy industries. Applications include oil extraction and pipeline leak areas, contaminated gas station sites, oil fields and shale gas fields, and oil depots.

[0079] C=C bond (aromatic hydrocarbons, polycyclic aromatic hydrocarbons): involved in coking, coal chemical industry, and combustion industry. Applicable to areas surrounding coal coking plants, tar processing plants, former gas plants, asphalt production plants, and waste incineration plants.

[0080] C=C bond (olefins, aromatic side chains): Involved in petrochemical cracking and plastics plants. Applicable to petrochemical cracking units, plastics and rubber manufacturing plants, synthetic resin and foam material factories, etc.

[0081] C≡C bond (alkynes): Involved in industrial gases and calcium carbide chemicals. Applicable to welding and metal processing plants, chemical synthesis gas production units, calcium carbide plants, gas storage and transportation stations, etc.

[0082] CH bonds (all hydrocarbons): Involves petrochemicals, energy and fuel production, and organic chemicals. It covers all the aforementioned hydrocarbon pollution scenarios.

[0083] C-Cl bond (chlorinated hydrocarbons, chlorinated aromatic hydrocarbons): Involved in dry cleaning and electronic cleaning. Applicable to electronic component cleaning plants, metal degreasing workshops, former dry cleaning shops, refrigerant production and maintenance areas, semiconductor industrial zones, etc.

[0084] C-Br bond (brominated hydrocarbon): Involved in flame retardants and fine chemicals. Applications include flame retardant manufacturing plants and fine chemical industrial parks.

[0085] CF bond (fluorinated hydrocarbons): Involved in refrigerants and fluorochemicals. Applications include refrigerant manufacturing plants and fluorochemical industrial parks.

[0086] CO bonds (phenols, ethers): Involved in phenol pollution and pharmaceutical plants. Applicable to sites contaminated with phenols, and wastewater treatment areas in pharmaceutical and fine chemical industries.

[0087] CN bond (aniline compounds, nitrogen-containing organic compounds): Involved in dyes, explosives, and the aniline industry. Applicable to dye factories, explosives and military factories, aniline production areas, leather processing plants, etc.

[0088] The above examples are merely partial application illustrations of the technical solutions of this invention in the field of organic pollutant treatment. Any medium environment in which the sonoluminescence free radical generation system provided by this invention can generate cavitation effect and induce chemical bond breaking should be considered within the scope of protection of this invention.

[0089] Sixth Embodiment like Figure 6 As shown, the sixth embodiment of the present invention provides a method for in-situ remediation of contaminated sites using the aforementioned sonoluminescence radical generation system, which is particularly suitable for porous media environments such as soil and groundwater. The following uses the remediation of organically contaminated soil as an example to illustrate its typical implementation process.

[0090] First, the spatial distribution range and boundaries of underground pollutants are determined through geophysical exploration, hydrogeological surveys, or monitoring well data, clarifying the morphology and trajectory of the pollution plume. Based on simulation software calculations, the borehole layout locations are determined, and the initial drive parameters of the ultrasonic transducer 10 (i.e., the initial configuration in step 1 of the control method) and the expected processing time (as the expected time for step 6) are predicted.

[0091] Vertical holes are drilled within the contaminated area at locations specified in the simulation results. The drilling depth is determined based on the location of the contaminated layer to facilitate the installation of the ultrasonic transducer 10 and sensor 14. After drilling, a casing is installed to support the borehole wall, prevent borehole collapse, and isolate different aquifers to avoid cross-contamination. This process includes lowering the sealing casing and installing a filter section at a depth corresponding to the target contaminated aquifer, either beforehand or after cementing. This filter section has narrow slits or round holes in a mesh structure, allowing groundwater and contaminants to freely enter the well casing. Subsequently, cement slurry or other sealing materials are injected into the annular space between the casing and the borehole wall to cement the well, securing the casing and preventing contaminants from migrating along the borehole wall.

[0092] The aforementioned steps of spatial positioning of the contamination plume, drilling, casing, and cementing all employ conventional techniques in this field. For contaminated areas where the aforementioned steps have been completed, the ultrasonic transducer 10 and sensor 14 can be directly immersed in the medium of the contaminated area. Water or other treatment agents can be injected into the contaminated area through the wellbore to ensure that the ultrasonic transducer 10 is completely immersed in the aqueous phase, thereby exciting dense cavitation bubbles. The high temperature and pressure generated by the collapse of the cavitation bubbles cause water molecules to pyrolyze and generate hydroxyl radicals, which simultaneously act directly on the covalent bonds of hydrocarbon macromolecules and organic pollutant molecules, causing them to break down into smaller molecule compounds.

[0093] Subsequently, the control method provided in the third embodiment of the present invention is used for ultrasonic cavitation repair, which includes steps 1 to 6. During the repair process, the acoustic luminescence radical generation system dynamically adjusts the driving frequency and output power of the ultrasonic transducer 10 based on the real-time feedback of the emission intensity from a sensor (such as an optical fiber probe, but not limited to this), to ensure that the cavitation effect continues to operate stably in the optimal state.

[0094] During the repair process, the pressure and temperature inside the well are monitored simultaneously until the expected treatment time is reached, at which point the operation is terminated. As an alternative, for complex media such as contaminated liquids, the ultrasonic transducer 10 and sensor 14 can also be immersed in the medium, and the above-mentioned control method can be used for in-situ cavitation repair.

[0095] Seventh Embodiment The seventh embodiment of the present invention provides a method for applying the above-mentioned sonoluminescence radical generation system to industrial production line cleaning operations. This method utilizes the sonoluminescence effect to continuously generate hydroxyl radicals, replacing traditional chemical cleaning processes such as water electrolysis and ozone water, and has significant advantages such as no chemical residue and safety and environmental friendliness.

[0096] In one embodiment of the present invention, multiple ultrasonic transducers are disposed in the cleaning zone corresponding to the cleaning process of the production line and are completely immersed in the cleaning medium (e.g., water). They operate with initially configured driving parameters to excite dense and controllable cavitation bubbles within the cleaning zone. Multiple fiber optic probes or immersion photoelectric sensors immersed in the cleaning medium collect the optical signals generated when the cavitation bubbles collapse in real time. A spectrum analyzer receives the optical signals and extracts the emitted light intensity (ultraviolet band integrated intensity) to determine whether the current cavitation intensity meets the preset requirements. If adjustment is required, a frequency parameterization scan is performed within a preset frequency range to identify the optimal frequency. The signal generator fixes the driving frequency of the ultrasonic transducers to this optimal frequency and gradually increases the output voltage amplitude in set steps, while dynamically monitoring the emitted light intensity and adjusting the output voltage until the emitted light intensity reaches the maximum value under the current conditions.

[0097] The items to be cleaned (such as vegetables, glass, and pharmaceuticals) are conveyed into the cleaning zone by a transfer device, completely immersed in the medium, and remain there for the predetermined time. Hydroxyl radicals oxidize and decompose organic contaminants on the surface of the items, while water flow simultaneously washes away impurities. After cleaning, the items are removed from the cleaning zone and proceed to the next process. Wastewater discharged from the cleaning zone is treated by a purification device and then recycled.

[0098] Taking a pre-cleaned vegetable washing production line as an example: Raw vegetables to be cleaned are placed in vegetable baskets and conveyed sequentially into the primary and secondary processing zones by a conveyor belt. Both processing zones are equipped with multiple ultrasonic transducers and multiple fiber optic probes, completely submerged in water. In the primary processing zone, cavitation bubbles collapse to generate hydroxyl radicals, decomposing pesticides and organic impurities on the surface of the vegetables. After discharge, the vegetables are sprayed with water to remove impurities before entering the secondary processing zone for deep purification. After secondary processing, they are sprayed again to complete the cleaning process. Fiber optic probes monitor the ultraviolet light intensity in both processing zones in real time. Based on this, the system dynamically adjusts the operating frequency and output power of the ultrasonic transducers to maintain a stable hydroxyl radical yield, ensuring consistent pesticide residue removal. Wastewater from the primary and secondary processing zones enters a wastewater purification device through an outlet pipe, and the purified water is recycled back to the washing zone.

[0099] The embodiments of the present invention achieve continuous, stable, and controllable in-situ generation of hydroxyl radicals through the sonoluminescence effect, which can effectively replace traditional cleaning processes such as water electrolysis and ozone water, providing a green, safe, and efficient online cleaning solution for industrial production lines.

[0100] It should be noted that the above embodiments are merely illustrative examples. The technical solutions of the various embodiments can be combined, and the order of the steps can be changed, all of which are within the protection scope of this invention.

[0101] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0102] The distributed ultrasonic transducer array and its control method provided by this invention have been described in detail above. Any obvious modifications made by those skilled in the art without departing from the essence of this invention will constitute an infringement of the patent rights of this invention and will incur corresponding legal liability.

Claims

1. A distributed ultrasonic transducer array, characterized in that... It includes multiple ultrasonic transducers, each of which includes a transducer head, an amplitude transformer, and a connecting wire; The transducer head is equipped with a piezoelectric ceramic crystal stack; The amplitude transformer is connected to the transducer head and is used to amplify the vibration displacement generated by the piezoelectric ceramic crystal stack. The connecting line is used to connect the ultrasonic transducer to the power amplifier module; The outer contour of the amplitude transformer includes multiple continuous cylindrical segments along the axial direction. Each cylindrical segment is formed by connecting a first cylindrical surface and a second cylindrical surface. The generatrices of the first cylindrical surface and the second cylindrical surface together form a circular arc or broken line symmetrical about the center line. The center line is perpendicular to the axis of the amplitude transformer, and each cylindrical segment forms an acoustic focus in the medium.

2. The distributed ultrasonic transducer array as described in claim 1, characterized in that: A straight line perpendicular to the generatrix of the first cylindrical surface, a straight line perpendicular to the generatrix of the second cylindrical surface, and the center line intersect at a point, which is the acoustic focal point formed by the cylindrical segment.

3. The distributed ultrasonic transducer array as described in claim 2, characterized in that: The distance from the acoustic focal point to the axis of the amplitude transformer is different for each of the cylindrical segments.

4. The distributed ultrasonic transducer array as described in claim 3, characterized in that: The radial distances from the acoustic focal points of each cylindrical segment of two adjacent ultrasonic transducers to their respective amplitude transformer axes are the same or complementary.

5. The distributed ultrasonic transducer array as described in any one of claims 1 to 4, characterized in that: The ultrasonic transducer operates in the frequency range of 20kHz to 100kHz.

6. The distributed ultrasonic transducer array as described in claim 5, characterized in that... It also includes a sensor positioned at a location capable of detecting spectral data of the region of maximum luminous flux generated by the ultrasonic transducer in the medium that induces cavitation bubbles.

7. A control method for a distributed ultrasonic transducer array according to any one of claims 1 to 6, characterized in that... Includes the following steps: Step 1: The signal generator receives the start signal and performs initial configuration of the drive frequency of each ultrasonic transducer; Step 2: Each ultrasonic transducer operates at the initially configured frequency, and the fiber optic probe collects the optical signal generated when cavitation bubbles collapse in the aqueous phase of the medium. Step 3: The spectrum analyzer receives the optical signal and decomposes it into a spectrum, extracts the integrated intensity of the ultraviolet band as the luminous intensity; changes the driving frequency with a set step size within a preset frequency range, records the luminous intensity corresponding to each frequency point, and determines the frequency corresponding to the maximum luminous intensity as the optimal frequency. Step 4: The signal generator fixes the driving frequency of each ultrasonic transducer to the optimal frequency, increases the output voltage amplitude step by step according to the set step size, and monitors the light intensity in real time, adjusting the output voltage until the light intensity reaches the maximum value under the current conditions.

8. The control method as described in claim 7, characterized in that: In step 1, the driving frequency of the ultrasonic transducer is initialized to the lowest frequency that causes cavitation in the aqueous phase of the medium and is acceptable for formation disturbance.

9. The control method as described in claim 7, characterized in that: The spectrum analyzer decomposes the optical signal into a spectrum and extracts the integrated intensity in the ultraviolet band as the emitted light intensity.

10. The control method as described in claim 9, characterized in that: The emitted light intensity is the integrated intensity of the ultraviolet band in the optical signal collected when the fiber optic probe is located in the maximum light flux region.

11. The control method as described in claim 7, characterized in that... Step 3 includes the following sub-steps: Step 31: Record the input voltage, current, power density and light intensity at the current driving frequency, and determine whether the light intensity is greater than or equal to the preset light intensity threshold. If so, proceed directly to step 4. Step 32: Under the control of the electronic control system, the command signal generator gradually changes the driving frequency within the preset frequency range with a constant output voltage amplitude and a set frequency step size. At each frequency point, the input active power and the corresponding light intensity are recorded, and the light intensity is plotted as a function of frequency. The frequency corresponding to the peak point of the curve is determined as the optimal frequency.

12. The control method as described in claim 7, characterized in that: The power density of the ultrasonic transducer is controlled within a range where the slope of the power density-luminous intensity relationship curve of the medium is greater than a preset threshold.

13. The control method as described in claim 7, characterized in that... Also includes: Step 5: The fiber optic probe detects the emitted light intensity again to determine if it has reached the expected intensity value; if it has, the current parameters are maintained and operation continues. If the optimal frequency is not reached, automatic frequency tracking will be activated, and a micro-frequency scan will be performed within the set frequency window with the optimal frequency as the center, and the driving frequency will be adjusted in real time to restore the light intensity to the maximum value. Step 6: When the continuous working time reaches the expected duration, the process ends.

14. A sonoluminescence radical generation system employing a distributed ultrasonic transducer array according to any one of claims 1 to 6, characterized in that... Includes electronic control system, signal generator, spectrum analyzer, oscilloscope, power amplifier module, fiber optic probe and preamplifier; The electronic control system is connected to the signal generator and the spectrum analyzer via a bus, respectively. The output of the signal generator is connected to the ultrasonic transducer via the power amplification module to drive the ultrasonic transducer to generate an ultrasonic cavitation effect in the medium. The fiber optic probe is used to collect the optical signal generated when cavitation bubbles collapse, and its output is connected to the oscilloscope and the spectrum analyzer via the preamplifier. The spectral analysis results output by the spectrum analyzer are transmitted to the electronic control system as a feedback signal, and the electronic control system adjusts the output parameters of the signal generator according to the feedback signal. The medium is optically opaque or has strong light absorption properties, or distorts the light propagation path, or has physical obstacles to light propagation, and the medium contains an aqueous phase that can participate in the reaction.

15. The sonoluminescence radical generation system as described in claim 14, characterized in that... It also includes an adaptive frequency tracking circuit module, which includes a microcontroller, a pulse generator, a power amplifier module, a matching network, a current detection module, and an A / D conversion module; The microcontroller controls the pulse generator to generate an electrical pulse signal. The electrical pulse signal is amplified in voltage and power by the power amplification module and then transmitted to the ultrasonic transducer via the matching network. The current detection module collects the operating current of the power amplifier module in real time and converts it into an analog signal. The A / D conversion module converts the analog signal into a digital signal and feeds it back to the microcontroller.

16. The sonoluminescence radical generation system as described in claim 14, characterized in that: The axis of the fiber optic probe is aligned with or parallel to the axis of the radiating surface of the ultrasonic transducer.

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