A novel transducer of nested double shell

Abstract

This invention discloses a novel nested double-shell transducer, relating to the field of transducer technology. Existing transducers suffer from low energy utilization, short effective operating distance, and poor receiving sensitivity. This invention utilizes an elliptical inner shell to generate a displacement amplification effect. A circumferentially gradient acoustic metamaterial layer is filled in the non-uniform gap between the inner and outer shells to achieve unidirectional sound wave transmission and impedance matching. A spiral-shaped, gradually changing acoustic prism is installed on the inner wall of the outer shell to convert the sound waves into a highly directional vortex beam. A dynamic impedance matching unit is installed on the outer surface of the outer shell, working in conjunction with an intelligent control module to achieve dual closed-loop adaptive control of the inner shell mode and the outer shell impedance. Through the synergistic effect of geometric amplification, material matching, and beam modulation, this invention improves energy utilization by 50%-70%, increases the effective operating distance by more than 2 times, significantly enhances receiving sensitivity, and widens the operating bandwidth by 2-3 times.

Description

Technical Field

[0001] This invention belongs to the field of transducer technology, specifically, it relates to a novel nested double-shell transducer. Background Technology

[0002] Underwater acoustic transducers are core components for electroacoustic energy conversion and are widely used in underwater communication, detection, and navigation. Traditional single-shell transducers are limited by the strain capacity of piezoelectric materials and the impedance mismatch between the shell and the medium, resulting in physical limitations in energy conversion efficiency, effective operating distance, and receiving sensitivity. These limitations make it difficult to meet the demands of modern underwater acoustic systems for high power, long distance, high sensitivity, and wide bandwidth.

[0003] While existing dual-shell transducers offer some structural strength enhancement or preliminary impedance matching, they still suffer from the following technical problems: First, the inner and outer shells are often concentric spheres or cylinders, limiting the vibration displacement of the inner shell to the strain of the piezoelectric material itself and lacking a mechanical amplification mechanism, thus restricting the boost to the sound source level. Second, the gap between the inner and outer shells is often filled with a homogeneous material, failing to eliminate impedance abrupt changes across the entire frequency band, resulting in significant energy reflection losses and difficulty in suppressing the back propagation of external noise. Third, they lack the ability to dynamically adjust the impedance between the outer shell and the external medium; changes in water depth, temperature, or operating frequency exacerbate impedance mismatch and drastically reduce energy utilization. Fourth, the radiated sound waves are mostly spherical waves or single-directional beams, resulting in energy dispersion and insufficient effective range. These interconnected problems make it difficult for existing transducers to achieve a comprehensive performance that balances high efficiency, long range, high sensitivity, and wide bandwidth.

[0004] There are currently no effective solutions to the problems in the relevant technologies.

[0005] Therefore, in order to solve the above problems, the present invention provides a novel transducer with a nested double housing. Summary of the Invention

[0006] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a novel transducer with a nested double-shell design.

[0007] The objective of this invention can be achieved through the following technical solutions: A novel nested double-shell transducer includes a fixed base, an outer shell mounted on top of the fixed base, an inner shell disposed inside the outer shell, and a sealing end cap disposed on top of the outer shell. The fixed base and the sealing end cap are connected by a support column. A core transducer assembly is encapsulated inside the inner shell. The core transducer assembly is connected to an external power supply circuit and a signal acquisition circuit through electrode leads. The inner shell is made of piezoelectric material and has an ellipsoidal geometry. It is used to generate a displacement amplification effect along the long axis under electrical excitation, thus forming mechanical vibration. A non-uniform gap is formed between the outer shell and the inner shell. This gap is filled with an acoustic metamaterial layer. The acoustic metamaterial layer has a gradient acoustic impedance along the circumference of the inner shell, which is used to realize unidirectional transmission of sound waves and impedance matching. The outer surface of the outer shell is provided with a dynamic impedance matching unit for real-time adjustment of the equivalent acoustic impedance between the core transducer component and the external medium. The core transducer component and the dynamic impedance matching unit are electrically connected to an intelligent control module.

[0008] As a preferred embodiment of the present invention, the inner shell is nested inside the outer shell, and a transition piece is provided between the outer shell and the inner shell. The transition piece is located at both ends of the short axis of the inner shell and is used to maintain the relative position of the outer shell and the inner shell.

[0009] As a preferred embodiment of the present invention, the ratio of the major axis to the minor axis of the inner shell is 1.5:1-3:1; the inner shell is radially polarized along its minor axis so that the strain in the minor axis direction is converted into amplified displacement output in the major axis direction through the ellipsoidal geometry.

[0010] As a preferred embodiment of the present invention, the inner shell adopts a partitioned polarization structure, wherein the polarization intensity of the regions at both ends of the long axis is higher than that of the region in the middle of the short axis, forming a low-frequency vibration region and a high-frequency vibration region.

[0011] As a preferred embodiment of the present invention, the thickness of the non-uniform gap is non-uniformly distributed along the circumference of the inner shell: the gap is smaller at both ends of the long axis of the inner shell and larger at both ends of the short axis. The acoustic impedance gradient of the acoustic metamaterial layer is matched with the thickness distribution of the non-uniform gap. A high impedance gradient change rate is used where the gap is small, and a slowly varying impedance gradient is used where the gap is large.

[0012] As a preferred embodiment of the present invention, the acoustic metamaterial layer is composed of a matrix material and periodically arranged local resonant units embedded in the matrix material; the volume fraction of the local resonant units decreases nonlinearly from the inside to the outside in the radial direction, so as to achieve a smooth transition of acoustic impedance from high voltage ceramic impedance to low water dielectric impedance.

[0013] As a preferred embodiment of the present invention, the inner wall of the outer shell is provided with an acoustic prism structure, which is spirally tapered and used to convert the spherical wave or asymmetric wave generated by the inner shell into a vortex beam or focused beam with a predetermined direction.

[0014] As a preferred embodiment of the present invention, the spiral-shaped gradual acoustic prism structure is an Archimedean spiral protrusion or groove, the pitch and depth of which gradually change along the circumference to match the main vibration direction of the inner shell and the sound wave front.

[0015] As a preferred embodiment of the present invention, the dynamic impedance matching unit includes multiple miniature piezoelectric cantilever beams distributed circumferentially along the outer surface of the shell. The intelligent control module adjusts the equivalent stiffness of the miniature piezoelectric cantilever beams by adjusting their bias voltage or parallel capacitance, thereby adjusting the equivalent acoustic impedance of the shell. As a preferred embodiment of the present invention, the intelligent control module includes a modal monitoring unit for real-time acquisition of the vibration state of the inner shell, an impedance monitoring unit for real-time acquisition of the impedance matching state between the dynamic impedance matching unit and the external medium, and a control unit for performing dual closed-loop adaptive control based on the vibration state and the impedance matching state.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention employs an elliptical inner shell and utilizes the displacement amplification effect of the ellipsoidal geometry to convert the strain in the short axis direction of the piezoelectric material into a displacement output of 3-5 times in the long axis direction under the same electrical power input. This significantly improves the mechanical vibration amplitude and sound source level, providing a physical basis for efficient energy conversion.

[0017] 2. This invention fills the non-uniform gap between the inner and outer shells with a circumferentially gradient acoustic metamaterial layer. Utilizing the distribution characteristics of the gap thickness along the circumferential direction, a high impedance gradient change rate is used to efficiently transfer energy at both ends of the long axis (large displacement, small gap), while a gradually varying gradient is used to absorb stray mode energy at both ends of the short axis (small displacement, large gap). This achieves unidirectional transmission of sound waves and wideband impedance matching, and the overall energy utilization rate is improved by 50%-70% compared to the traditional spherical double-shell structure.

[0018] 3. The present invention provides a spiral-shaped gradient acoustic prism on the inner wall of the outer shell, which converts the sound waves generated by the inner shell into a highly directional vortex beam or focused beam. Combined with the main radiation characteristics of the major axis of the elliptical inner shell, the sound source level is increased by 8dB-12dB and the effective working distance is increased by more than 2 times.

[0019] 4. This invention constructs a dual-closed-loop adaptive control system consisting of an inner shell modal closed loop and an outer shell impedance closed loop through a dynamic impedance matching unit on the outer surface of the shell. When operating conditions such as operating frequency and water depth change, the system adjusts the excitation parameters and impedance matching parameters in real time to ensure that the transducer is always in the optimal energy conversion state across the entire frequency band and all operating conditions. At the same time, the displacement amplification effect of the elliptical shell in the receiving mode enhances the induction of weak signals, improves the receiving sensitivity by 5dB-8dB, and increases the operating bandwidth by 2-3 times. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the planar structure of the present invention.

[0022] Figure label: 1. Fixed base; 2. Outer shell; 3. Inner shell; 4. Transition component; 5. Core transducer assembly; 6. Acoustic metamaterial layer; 7. Sealed end cap; 8. Support column; 9. Electrode lead wire; 10. Acoustic prism structure; 11. Miniature piezoelectric cantilever beam. Detailed Implementation

[0023] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention: Example: Please refer to Figure 1-2 According to an embodiment of the present invention, a novel nested double-shell transducer includes a fixed base 1, an outer shell 2, an inner shell 3, a transition piece 4, a core transducer assembly 5, an acoustic metamaterial layer 6, a sealed end cap 7, a support column 8, an electrode lead 9, an acoustic prism structure 10, and a micro piezoelectric cantilever beam 11. The core transducer assembly 5 and the micro piezoelectric cantilever beam 11 are both electrically connected to an intelligent control module through the electrode lead 9.

[0024] Specifically, the fixed base 1 is made of stainless steel and is plate-shaped, used to install and fix the transducer to the working platform. A shell 2, cylindrical in shape and made of titanium alloy, is mounted on the top of the fixed base 1. A sealing end cap 7, made of rubber, is provided at the top of the shell 2, and a sealing ring ensures a watertight seal between the sealing end cap 7 and the shell 2. The fixed base 1 and the sealing end cap 7 are connected by support columns 8, which are made of hollow stainless steel tubes. Four support columns 8 are evenly distributed circumferentially to enhance the overall structural strength.

[0025] Specifically, an inner shell 3 is nested inside the outer shell 2. The inner shell 3 has an elliptical cross-section and is made of type 1-3 piezoelectric ceramic composite material, with a major-to-minor axis ratio of 2:1. The inner shell 3 is polarized along its minor axis. To achieve zoned polarization, during the polarization process, the polarization electric field intensity applied to the two ends of the major axis is 1.5 times that of the middle region of the minor axis, thereby giving the two ends of the major axis a higher residual polarization intensity, forming a low-frequency vibration region (resonant frequency of approximately 50kHz), and the middle region of the minor axis forms a high-frequency vibration region (resonant frequency of approximately 150kHz). The inner shell 3 encapsulates a core transducer component 5, which consists of a piezoelectric ceramic crystal stack and a matching layer, and is tightly fitted to the inner wall of the inner shell 3 to enhance the electroacoustic conversion efficiency. The core transducer component 5 is connected to the external power supply circuit and signal acquisition circuit through electrode leads 9, which are flexible wires led out from inside the inner shell 3.

[0026] Specifically, the inner shell 3 and the outer shell 2 are fixed in relative position by a transition piece 4. The transition piece 4 is an annular washer made of elastic rubber material, and two of them are provided, which are respectively installed between the two ends of the short axis of the inner shell 3 and the inner wall of the outer shell 2. The transition piece 4 is fixed to the inner shell 3 and the outer shell 2 by adhesive bonding. While maintaining the relative position, it allows the inner shell 3 to vibrate freely in the long axis direction, reducing the energy loss of mechanical vibration to the outer shell 2.

[0027] Specifically, a non-uniform gap is formed between the inner shell 3 and the outer shell 2. The thickness of this gap is linearly and gradually distributed along the circumference of the inner shell 3: the gap is smallest at both ends of the long axis of the inner shell 3, which is 3 mm; the gap is largest at both ends of the short axis, which is 8 mm; and the gap thickness increases uniformly from the long axis end to the short axis end.

[0028] Specifically, the non-uniform gap is filled with an acoustic metamaterial layer 6. The acoustic metamaterial layer 6 consists of an epoxy resin matrix and periodically arranged tungsten spheres embedded within the matrix. The tungsten spheres have a diameter of 0.3 mm, are arranged in a square lattice, and have a lattice constant of 0.5 mm. The acoustic impedance of the acoustic metamaterial layer 6 exhibits gradient changes along both the radial and circumferential directions. Along the radial direction, from the outer surface of the inner shell 3 to the inner surface of the outer shell 2, the volume fraction of the tungsten spheres decreases exponentially: volume fraction , where r is the radial distance and k is the attenuation coefficient (k=0.8 in this embodiment), so that the volume fraction decreases smoothly from 25% to 5%, achieving a smooth transition of acoustic impedance from the piezoelectric ceramic impedance of the inner shell 3 (about 30MRayl) to the water medium impedance (about 1.5MRayl). Along the circumferential direction, in the regions at both ends of the long axis where the gap is smaller, the attenuation coefficient k of the tungsten sphere volume fraction along the radial direction is 1.0, which is a high impedance gradient change rate; in the regions at both ends of the short axis where the gap is larger, the attenuation coefficient k is 0.6, which is a slowly varying impedance gradient. Through this circumferential gradient design, acoustic energy is transmitted efficiently in the long axis direction, while stray mode energy is suppressed in the short axis direction.

[0029] Specifically, a dynamic impedance matching unit is provided on the outer surface of the outer shell 2. This unit includes multiple miniature piezoelectric cantilever beams 11 uniformly distributed circumferentially along the outer surface of the outer shell 2. The miniature piezoelectric cantilever beams 11 are made of PZT-5H piezoelectric ceramic material. The root of each miniature piezoelectric cantilever beam 11 is fixed to the outer surface of the outer shell 2 with epoxy resin adhesive, and the free end is suspended. When the intelligent control module adjusts the bias voltage of the miniature piezoelectric cantilever beam 11, the equivalent stiffness of the cantilever beam changes, and its resonant frequency changes accordingly. Due to the mechanical coupling between the miniature piezoelectric cantilever beam 11 and the outer shell 2, the impedance change of the cantilever beam will affect the equivalent acoustic impedance of the outer shell 2 through mechanical coupling, thereby realizing the dynamic adjustment of the impedance matching between the outer shell 2 and the external medium.

[0030] Specifically, the intelligent control module includes a modal monitoring unit, an impedance monitoring unit, and a control unit: The modal monitoring unit includes two resistance strain gauges (two in total) attached to the outer surfaces of both ends of the long axis of the inner shell 3, and a voltage monitoring circuit built into the core transducer component 5, which is used to collect the vibration amplitude and frequency of the inner shell 3 in real time and obtain the vibration state of the inner shell 3 and the core transducer component 5. The impedance monitoring unit detects changes in the resonant frequency of the miniature piezoelectric cantilever beam 11 to determine the impedance matching status between the outer shell 2 and the external medium. The principle is as follows: when the impedance matching between the outer shell 2 and the external medium is good, the acoustic energy radiation efficiency is high, the mechanical load on the miniature piezoelectric cantilever beam 11 is minimal, and the resonant frequency is highest; when there is impedance mismatch, the mechanical load on the cantilever beam increases, and the resonant frequency decreases. The impedance monitoring unit obtains the current resonant frequency of each cantilever beam through frequency sweep measurement and compares it with a preset target frequency to obtain the impedance matching deviation. The control unit adjusts the amplitude, frequency, and phase of the excitation voltage of the core transducer 5 in real time based on the vibration state of the inner shell 3 obtained by the modal monitoring unit, ensuring that the inner shell 3 always operates in the displacement amplification mode (i.e., the excitation frequency is close to the resonant frequency of the long axis of the inner shell 3). Simultaneously, the control unit adjusts the bias voltage (range from 0V to 100V) of the micro piezoelectric cantilever beam 11 in real time based on the impedance matching deviation obtained by the impedance monitoring unit, changing the equivalent stiffness of the cantilever beam to maintain the equivalent acoustic impedance of the outer shell 2 matching with the external medium. These two closed-loop controls work independently yet collaboratively: the sampling frequency of the inner shell 3 modal closed loop is 10kHz, and the sampling frequency of the impedance matching closed loop is 1kHz, forming a dual-closed-loop adaptive control system.

[0031] In receiving mode, external sound waves act on the outer shell 2 and are efficiently transmitted to the inner shell 3 and the core transducer component 5 via the unidirectional transmission channel of the acoustic metamaterial layer 6. The ellipsoidal structure of the inner shell 3 exerts a displacement amplification effect: when a weak sound pressure acts on the ellipsoidal shell, a larger strain is generated at both ends of the long axis, thereby inducing a stronger electrical signal in the piezoelectric material. At the same time, the core transducer component 5 further converts the sound signal into an electrical signal, thereby improving the receiving sensitivity. The electrical signal is transmitted to the signal acquisition circuit via the electrode leads 9, completing the sound wave reception.

[0032] The working principle of a novel nested double-shell transducer is as follows: In transmission mode, the intelligent control module applies an excitation signal to the inner shell 3 according to a preset operating frequency. Since the inner shell 3 adopts an ellipsoidal structure and is polarized along its short axis, the stretching strain of the piezoelectric material along the short axis is converted into a larger axial displacement output at both ends of the long axis through the curvature change of the ellipsoidal shell, producing a displacement amplification effect with an amplification factor of approximately 3 to 5 times. Large-amplitude mechanical vibrations are generated at both ends of the long axis of the inner shell 3, exciting sound waves. The sound waves first propagate to the acoustic metamaterial layer 6 within the non-uniform gap between the inner shell 3 and the outer shell 2. Due to its circumferential gradient impedance design, the acoustic metamaterial layer 6 achieves highly efficient energy transfer at both ends of the long axis, transmitting the acoustic energy generated by the large-amplitude vibration to the outer shell 2 with almost no reflection. At both ends of the short axis, the acoustic metamaterial layer 6 absorbs and suppresses stray mode energy, while utilizing the unidirectional transmission characteristics of its local resonant units to prevent external noise from entering the inner shell 3 in the reverse direction. When the sound waves propagate to the inner wall of the outer shell 2, they are modulated by the acoustic prism structure 10. The acoustic prism structure 10 features a gradually changing Archimedean spiral, causing phase modulation of the wavefront of sound waves passing through its surface, forming a vortex beam with orbital angular momentum. This vortex beam exhibits non-diffraction characteristics, and its energy remains focused during propagation, resulting in high directivity of the transducer along its long axis, significantly improving the axial sound source level and effective operating distance. Simultaneously, the intelligent control module monitors the vibration modes of the inner shell 3 in real time. When the operating frequency changes, the control unit adjusts the amplitude, frequency, and phase of the excitation signal to ensure that the inner shell 3 always operates in the displacement amplification mode. Furthermore, the intelligent control module monitors the impedance state of the micro-piezoelectric cantilever beam 11, adjusting its bias voltage or parallel capacitance in real time to change its equivalent stiffness, thereby adjusting the equivalent acoustic impedance of the outer shell 2, ensuring optimal impedance matching between the outer shell 2 and the external medium across the entire frequency band and water depth range. These two closed-loop controls work independently yet collaboratively, forming a dual-closed-loop adaptive control system that ensures the transducer maintains optimal energy conversion efficiency under various operating conditions. In receiving mode, external sound waves act on the outer shell 2 and are efficiently transmitted to the inner shell 3 via the unidirectional transmission channel of the acoustic metamaterial layer 6. The ellipsoidal structure of the inner shell 3 again exerts a displacement amplification effect: when a weak sound pressure acts on the ellipsoidal shell, a larger strain is generated at both ends of the long axis, thereby inducing a stronger electrical signal in the piezoelectric material and improving the receiving sensitivity. The electrical signal is transmitted to the signal acquisition circuit via the electrode leads on the inner shell 3 to complete the sound wave reception.

[0033] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel nested double-shell transducer, comprising a fixed base (1), an outer shell (2) mounted on the top of the fixed base (1), an inner shell (3) disposed inside the outer shell (2), and a sealing end cap (7) disposed on the top of the outer shell (2), wherein the fixed base (1) and the sealing end cap (7) are connected by a support column (8), and a core transducer assembly (5) is encapsulated inside the inner shell (3), wherein the core transducer assembly (5) is connected to an external power supply circuit and a signal acquisition circuit through electrode leads (9), characterized in that: The inner shell (3) is made of piezoelectric material and has an ellipsoidal geometry. It is used to generate a displacement amplification effect along the long axis under electrical excitation, thereby forming mechanical vibration. A non-uniform gap is formed between the outer shell (2) and the inner shell (3). The gap is filled with an acoustic metamaterial layer (6). The acoustic metamaterial layer (6) has a gradient acoustic impedance along the circumference of the inner shell (3) to realize unidirectional transmission of sound waves and impedance matching. The outer surface of the outer shell (2) is provided with a dynamic impedance matching unit for real-time adjustment of the equivalent acoustic impedance between the core transducer component (5) and the external medium. The core transducer component (5) and the dynamic impedance matching unit are electrically connected to an intelligent control module.

2. The novel nested double-shell transducer according to claim 1, characterized in that: The inner shell (3) is nested inside the outer shell (2). A transition piece (4) is provided between the outer shell (2) and the inner shell (3). The transition piece (4) is located at both ends of the short axis of the inner shell (3) to maintain the relative position of the outer shell (2) and the inner shell (3).

3. A novel nested double-shell transducer according to claim 1, characterized in that: The ratio of the major axis to the minor axis of the inner shell (3) is 1.5:1-3:1; the inner shell (3) is radially polarized along its minor axis so that the strain in the minor axis direction is converted into amplified displacement output in the major axis direction through the ellipsoidal geometry.

4. A novel nested double-shell transducer according to claim 3, characterized in that: The inner shell (3) adopts a partitioned polarization structure, with the polarization intensity at both ends of its long axis being higher than that in the middle of its short axis, forming a low-frequency vibration zone and a high-frequency vibration zone.

5. A novel nested double-shell transducer according to claim 1, characterized in that: The thickness of the non-uniform gap is non-uniformly distributed along the circumference of the inner shell (3): the gap is smaller at both ends of the long axis of the inner shell (3) and larger at both ends of the short axis. The acoustic impedance gradient of the acoustic metamaterial layer (6) is matched with the thickness distribution of the non-uniform gap. A high impedance gradient change rate is used where the gap is small, and a slowly varying impedance gradient is used where the gap is large.

6. A novel nested double-shell transducer according to claim 1, characterized in that: The acoustic metamaterial layer (6) is composed of a matrix material and periodically arranged local resonant units embedded in the matrix material; the volume fraction of the local resonant units decreases nonlinearly from the inside to the outside in the radial direction to achieve a smooth transition of acoustic impedance from high voltage ceramic impedance to low water dielectric impedance.

7. A novel nested double-shell transducer according to claim 1, characterized in that: The inner wall of the outer shell (2) is provided with an acoustic prism structure (10), which is spirally tapered and is used to convert the spherical wave or asymmetric wave generated by the inner shell (3) into a vortex beam or focused beam with a predetermined direction.

8. A novel nested double-shell transducer according to claim 7, characterized in that: The spiral-shaped gradient acoustic prism structure is an Archimedean spiral protrusion or groove, with its pitch and depth gradually changing along the circumference to match the main vibration direction of the inner shell (3) and the sound wave front.

9. A novel nested double-shell transducer according to claim 1, characterized in that: The dynamic impedance matching unit includes multiple miniature piezoelectric cantilever beams (11) distributed circumferentially along the outer surface of the shell (2). The intelligent control module adjusts the equivalent stiffness of the miniature piezoelectric cantilever beams (11) by adjusting the bias voltage or parallel capacitance of the miniature piezoelectric cantilever beams (11), thereby adjusting the equivalent acoustic impedance of the shell (2).

10. A novel nested double-shell transducer according to claim 1, characterized in that: The intelligent control module includes a modal monitoring unit for real-time acquisition of the vibration state of the inner shell (3), an impedance monitoring unit for real-time acquisition of the impedance matching state between the dynamic impedance matching unit and the external medium, and a control unit for performing dual closed-loop adaptive control based on the vibration state and impedance matching state.

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