Low-frequency underwater fluid sound production device

Abstract

The invention belongs to the technical field of underwater acoustic transducers, and relates to a low-frequency underwater fluid sound production device which comprises a power assembly, a rotating assembly and a transduction assembly which are connected in sequence. The transduction assembly comprises a center shaft and a multi-stage blade type transducer connected to the center shaft in series. The power assembly converts fuel chemical energy into fluid kinetic energy so as to drive the rotating assembly. The rotating assembly rotates under the impact of the power assembly and drives the central shaft of the transduction assembly to rotate so as to convert fluid kinetic energy into mechanical kinetic energy; a blade type transducer of the transduction assembly is linked with the center shaft, so that a blade structure of the blade type transducer rotates and swings, water flow with the flow periodically changing along with time is generated, low-frequency sound radiation is formed, mechanical kinetic energy is converted into sound energy, and low-frequency underwater fluid sound production is achieved. According to the invention, wide-frequency-band and high-power radiation can be realized at the same time, and the sound source intensity is high.

Description

Technical Field

[0001] The present application relates to the technical field of underwater acoustic transducers, and in particular to a low-frequency underwater fluid sound-generating device. Background Art

[0002] Low-frequency underwater fluid sound-generating devices or low-frequency underwater acoustic transducers are mainly used to generate low-frequency sound waves underwater. They are sound-generating devices that convert other energy into sound energy. The noise radiated by underwater targets is concentrated in the low-frequency band. At the same time, low-frequency sound waves have the unique advantage of long propagation distance, which makes low-frequency transducers have very important application prospects in marine research and national defense construction. Specific application areas include underwater acoustic detection, confrontation, target simulation, long-distance communication, and underwater strong sound denial. For example, low-frequency sound waves are used as a carrier for information exchange of underwater operating equipment and as a simulation of important characteristics of the "soundprint" of underwater targets. The quality of the transducer technology will directly determine the actual application effect.

[0003] In the prior art, low-frequency underwater acoustic transducers mainly include basic types such as piezoelectric, electric and fluid dynamic.

[0004] Piezoelectric transducers generally produce sound by stimulating structural vibration through piezoelectric materials. Most transducers work in a resonant mode, so the sound frequency band is relatively narrow and cannot meet the requirements of low-frequency / very low-frequency wide-band radiation. At the same time, the transducer has a large radiation surface, and the volume, weight and cost of the transducer are high. The key vibration amplitude is limited by the structural material and strength, making it difficult to achieve low-frequency and high-power radiation.

[0005] Electric transducers mostly use dynamic coil excitation, relying on the Ampere force between electric current and magnetic field as the excitation source to drive the piston to vibrate and make sound. The reciprocating vibration of the sound source surface is the source of sound energy. They generally work in the audible sound frequency band and have a wide working frequency band. However, in the low frequency / very low frequency band, it is also difficult to achieve the purpose of low-frequency and high-power radiation due to the small radiation area and structural vibration amplitude.

[0006] Fluid dynamic transducers convert fluid kinetic energy into acoustic energy through transient flow processes. Compared with piezoelectric or electric transducers, the advantage of this type of transducer is that the amplitude of the vibration is not constrained or limited by the sound radiation structure, so it is suitable for scenes that require large amplitude radiation. Typical devices include reed whistles with higher sound frequencies, underwater whistles, and blade transducers with lower sound frequencies. The disadvantage is that reed whistles generally work at high frequencies. Although underwater whistles can achieve larger radiation surface amplitudes, it is difficult to overcome the contradiction between lower volume, weight, and cost and larger radiation area.

[0007] In summary, the low-frequency underwater acoustic transducer in the prior art cannot achieve wide frequency band and high-power radiation at the same time, and it is difficult to maintain high-efficiency energy in the low frequency band, and the sound source intensity is not high. Summary of the invention

[0008] Based on this, it is necessary to provide a low-frequency underwater fluid sound-generating device to address the above-mentioned technical problems, which can generate low-frequency / very low-frequency sound waves underwater, while achieving wide-band and high-power radiation, and has high sound source intensity and small size.

[0009] A low-frequency underwater fluid sound-generating device comprises: a power assembly, a rotating assembly and a transducer assembly connected in sequence; the transducer assembly comprises: a central axis and a multi-stage blade transducer connected in series to the central axis; The power component converts the chemical energy of the fuel into the kinetic energy of the fluid to drive the rotating component; The rotating assembly rotates under the impact of the power assembly, and drives the central axis of the energy conversion assembly to rotate, so as to convert the fluid kinetic energy into mechanical kinetic energy; The blade transducer of the transducer assembly is linked with the central axis, so that the blade structure of the blade transducer rotates and swings, generating a water flow whose flow rate changes periodically with time, forming low-frequency sound radiation, so as to convert mechanical kinetic energy into sound energy and realize low-frequency underwater fluid sound generation.

[0010] In one embodiment, the transducer assembly further comprises: a duct; The duct is a cylindrical annular structure, which is sleeved at intervals on the outside of all blade-type transducers and is rotatably connected to the central shaft; One end of the central shaft is arranged at one end of the duct, and the other end passes through the other end of the duct and is connected to the rotating component.

[0011] In one embodiment, the energy conversion component further includes: a synchronous controller, a power amplifier and a vibration displacement sensor; The synchronous controller adopts a synchronous control algorithm to calculate and obtain an excitation signal, and inputs the excitation signal to the power amplifier; The power amplifier outputs a control signal according to the excitation signal to excite the blade-type transducer to generate vibration; The vibration displacement sensor is connected to the blade transducer to obtain vibration information of the blade transducer, generate a vibration signal, and send it to the synchronization controller to correct the excitation signal; The synchronous controller, the power amplifier and the vibration displacement sensor work together to achieve synchronous driving and consistent excitation.

[0012] In one embodiment, the synchronization control algorithm includes: outer loop control and inner loop control; The outer loop control includes: identifying and synthesizing the amplitude of the signal of the vibration displacement sensor and comparing it with the vibration reference signal to perform outer loop amplitude correction so that the response amplitude of the device is equal to the set vibration amplitude; The inner loop control includes: identifying the amplitude of the synchronous controller signal and comparing it with the signal obtained by the outer loop amplitude correction to perform inner loop amplitude correction; identifying and compensating the phase difference between the synchronous controller signals; and generating various drive signals by integrating the inner loop amplitude corrected signal, the compensated phase and the sinusoidal signal source to synchronize the vibration.

[0013] In one embodiment, the blade transducer comprises: a blade structure and a driving structure; The blade structure is arranged on the central shaft so as to rotate simultaneously with the rotation of the central shaft; The driving structure is connected to the blade structure so as to drive the blade structure to generate periodic swing when being excited.

[0014] In one embodiment, the blade transducer further comprises: a mounting bearing disposed on the central axis; The blade structure and the driving structure are both connected to the central shaft via the assembled bearing.

[0015] In one embodiment, the spacing between the first-stage blade transducer and the last-stage blade transducer is smaller than the wavelength corresponding to the working frequency of the low-frequency underwater fluid sound generating device.

[0016] In one embodiment, the rotating assembly includes: a turbine; The turbine is arranged on the central shaft so as to rotate under the impact of the power assembly and drive the central shaft to rotate.

[0017] In one embodiment, the rotating assembly further comprises: a generator connected to the turbine; The generator is disposed on the central shaft to generate electricity while the central shaft rotates.

[0018] In one embodiment, the power assembly includes: a fuel tank and a nozzle connected to the fuel tank; The underwater fuel in the fuel tank reacts chemically with water to generate a high-pressure fluid medium, which is ejected through the nozzle to form a high-speed jet.

[0019] The above-mentioned low-frequency underwater fluid sound-generating device uses a blade-type transducer as the basic sound-generating unit. By connecting low-frequency / very low-frequency blade-type transducers in multiple stages in series, centrally coaxially rotating and synchronously driving, the problem that the sound intensity and sound power of a single blade-type transducer cannot be improved due to insufficient strength of the blade structure itself and limited displacement of the blade swing drive is solved, and the consistency (synchronicity) of the swing of blade components at each level is achieved to superimpose the sound intensity and realize wide-band, high-power, high-intensity low-frequency sound radiation; by adding ducts to the periphery of the multi-stage blade-type transducer and introducing high-energy-density energy supplies such as fuel reactions, internal and external The mutual influence of fluid media further improves the low-frequency radiation efficiency; underwater chemical reactions are used instead of electrical energy to increase energy density and improve the compactness of the device; synchronous control is applied to blade transducers at each level, and a synchronous controller is used to obtain the blade swing drive displacement inside the blade transducer at each level and output a correction signal to the power amplifier. A synchronous control algorithm is used to complete the feedback control of the displacement, and the multi-level drive is controlled to achieve good consistency, avoiding the radiation signal effect caused by the difference in structure and excitation at each level; a power component, a rotating component and a transducer component are designed, and the three cooperate with each other. The rotation and swing of the blades change the blade angle of attack, thereby adjusting the flow generated by the blade movement, and under the drive of the power component, the sound generation efficiency is improved. That is to say, the present application generates sound by regulating the change of flow over time. The device itself does not contain structural vibration. The sound generation principle does not come from structural vibration, but the fluctuation of pressure and density generated when the fluid flow changes and the fluctuation is propagated in the form of sound waves. In principle, it overcomes the shortcomings of traditional low-frequency transducers under low-frequency and high-power conditions. The volume and vibration amplitude are limited; through the coordinated cooperation of the above-mentioned technical features, high-power low-frequency sound wave radiation can be efficiently generated in the underwater low-frequency / very low-frequency band. A low-frequency underwater fluid sound-generating device with wide bandwidth, high sound intensity, high power, large radiation area, high vibration amplitude of the radiation surface, economy, stability and reliability, and small volume and weight can be realized, and high-efficiency radiation in the low-frequency band can be achieved, which is suitable for practical applications, especially for scenarios such as underwater acoustic detection and confrontation (for example: in order to accurately simulate the low-frequency sound radiation of underwater operating equipment targets for long-distance detection, it is necessary to be close to the actual target in terms of both spectral characteristics and sound power, and the transducer is required to efficiently generate high-power sound wave energy in the frequency band below 300 Hz), which is expected to significantly improve the relevant underwater acoustic detection, environmental observation and underwater acoustic confrontation capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of a low-frequency underwater fluid sound-generating device in one embodiment; Figure 2 is a structural diagram of a low-frequency underwater fluid sound-generating device in one embodiment; Figure 3 is an isometric diagram of a low-frequency underwater fluid sound generating device in one embodiment; Figure 4is an isometric cross-sectional view of a low-frequency underwater fluid sound generating device in one embodiment; Figure 5 It is an installation diagram of a low-frequency underwater fluid sound-generating device in one embodiment; Figure 6 A cross-sectional view of the installation relationship of a low-frequency underwater fluid sound-generating device in one embodiment; Figure 7 A schematic diagram of a blade-type transducer of a low-frequency underwater fluid sound-generating device in one embodiment; Figure 8 A schematic cross-sectional view of a blade-type transducer of a low-frequency underwater fluid sound-generating device in one embodiment; Fig. 9 A partial schematic diagram of a blade-type transducer of a low-frequency underwater fluid sound-generating device in one embodiment; Fig.10 The figure is a schematic diagram of a synchronization control algorithm of a synchronization controller of a low-frequency underwater fluid sound generating device in one embodiment.

[0021] Reference numerals: 1 transducer assembly (transducer section), 2 power assembly (power section), 3 rotating assembly (rotating section), 4 blade structure, 5 central shaft, 6 duct, 7 driving structure, 8 fuel tank, 9 nozzle, 10 turbine, 11 generator, 12 power amplifier, 13 synchronous controller, 14 vibration displacement sensor; Blade seat 41, blade assembly 42, needle roller bearing 43; Permanent magnet 71 , coil 72 , adapter 73 , connecting rod 74 . DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0023] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, etc., unless otherwise clearly and specifically defined.

[0025] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0027] The present application provides a low-frequency underwater fluid sound generating device, such as Figures 1 to 9 As shown, in one embodiment, it includes: a power component (power section), a rotating component (rotating section) and a transducing component (transducing section), and the power component, the rotating component and the transducing component are connected in sequence.

[0028] 1. Power components The power assembly converts the chemical energy of the fuel into the kinetic energy of the fluid to drive the rotating assembly.

[0029] The power assembly includes: a fuel tank and a nozzle, the fuel tank is connected to the nozzle; preferably, there are multiple fuel tanks and nozzles and they correspond one to one, the fuel tanks are connected to the corresponding nozzles and serve as a power unit, and the multiple power units are arranged in an array in the circumferential direction outside the duct of the transducer assembly, and the axes of all the power units are parallel to the central axis of the transducer assembly.

[0030] 2. Rotating assembly The rotating component rotates under the impact of the power component and provides rotational power to the central shaft, driving the central shaft of the energy conversion component to rotate, so as to convert the fluid kinetic energy into mechanical kinetic energy and electrical energy.

[0031] The rotating assembly includes: a turbine and a generator, the turbine is connected to the generator; the turbine is arranged on the central shaft to rotate under the impact of the power assembly and drive the central shaft to rotate; the generator is arranged on the central shaft to generate electricity while the central shaft rotates. The turbine and the generator are arranged on the central shaft in a coaxial series manner to cooperate with the power assembly to provide rotational power for the central shaft of the energy conversion assembly. The design of the generator has the characteristics of high energy density, avoids carrying an external power supply or power supply line, and improves the compactness and portability of the device.

[0032] 3. Transducer components The transducing component performs transduction under the driving of the rotating component to convert mechanical kinetic energy into sound energy.

[0033] The energy conversion assembly includes: a central axis, a plurality of blade-type energy conversion devices, a duct, a synchronous controller, a power amplifier and a vibration displacement sensor.

[0034] The central shaft is a component shared by the transducer assembly and the rotating assembly. Specifically, the multiple blade transducers, duct and rotating assembly of the transducer assembly are all mounted on the outside of the central shaft; the central shaft, the multiple blade transducers arranged at one end of the central shaft and the rotating assembly arranged at the other end of the central shaft are all linked.

[0035] Multiple blade transducers are arranged on the central axis in a coaxial series manner to form a series of multi-stage blade transducers; the blade transducers are linked to the central axis, and the rotation of the central axis drives the blade transducers of each stage, so that the blade structure of the blade transducer rotates and swings, generating a water flow whose flow rate changes periodically with time, forming low-frequency sound radiation, so as to convert mechanical kinetic energy into sound energy and realize low-frequency underwater fluid sound generation.

[0036] The duct is a cylindrical ring structure, which is sleeved at intervals on the outside of all blade-type transducers and is rotatably connected to the central axis through bearings (specifically: a plurality of radial walls are arranged at intervals on the inner wall of the duct along the length direction of the central axis as connecting parts, and the connecting parts are rotatably connected to the central axis through bearings) so as to maintain a relatively static state when the central axis rotates; one end of the central axis is arranged at one end of the duct, and the other end passes through the other end of the duct and is connected to the rotating component; the middle part of the duct is recessed toward the central axis, so that a first space for arranging the transducer component is formed inside one end of the duct, and a first space for arranging the transducer component is formed inside the duct. The other end forms a second space for setting the rotating assembly, the middle outer side of the duct forms a third space for setting the power assembly, and the middle inner side of the duct forms a fourth space for setting part of the central axis; the connection between the middle of the duct and the other end is provided with a plurality of flow holes along the circumferential direction, the axis direction of the flow holes is parallel to the axis direction of the central axis, and the nozzle of the power assembly corresponds to the flow holes one by one, and the end of the nozzle not connected to the fuel tank is connected to the corresponding flow hole to form a jet channel, so that the high-speed jet ejected from the nozzle passes through the jet channel and impacts the turbine of the rotating assembly. The duct plays a role similar to that of an acoustic baffle in the radiation of a piston sound source, avoiding the compensatory filling of the fluid medium inside and outside the duct under the action of the pressure difference of the sound field, so as to improve the low-frequency radiation efficiency.

[0037] The synchronous controller adopts a synchronous control algorithm to obtain an excitation signal based on an initial signal (obtained from a signal generator) and input it into the power amplifier.

[0038] The power amplifier outputs a control signal according to the excitation signal to excite the driving structure of the blade-type transducer to generate vibration.

[0039] The vibration displacement sensor is connected to the driving structure of the blade transducer to obtain the vibration information of the blade transducer, generate a vibration signal, and send it to the synchronization controller to correct the excitation signal so that the signal meets the consistency excitation requirement.

[0040] Among them, the synchronous controller, power amplifier and vibration displacement sensor work together to achieve synchronous drive and consistent excitation.

[0041] like Fig.10As shown, specifically, the synchronous control algorithm includes: outer loop control and inner loop control; the outer loop control includes: performing amplitude identification and synthesis on the signal of the vibration displacement sensor and comparing it with the vibration reference signal to perform outer loop amplitude correction so that the response amplitude of the device is equal to the set vibration amplitude; the inner loop control includes: performing amplitude identification on the signal of the synchronous controller and comparing it with the signal obtained by the outer loop amplitude correction to perform inner loop amplitude correction; identifying and compensating the phase difference between the synchronous controller signals; and generating each drive signal by integrating the signal after the inner loop amplitude correction, the compensated phase and the sinusoidal signal source to synchronize the vibration. More specifically, the synchronous control algorithm includes: outer loop control and inner loop control; the outer loop control includes: amplitude identification of the signal of the vibration displacement sensor, and synthesis of the identified amplitude signal according to the control strategy (such as average control, maximum response control, minimum response control, etc.), and comparing the synthesized control signal with the vibration reference signal to perform outer loop amplitude correction to make the response amplitude of the device equal to the set vibration amplitude; the inner loop control includes: amplitude identification of the signal of the synchronous controller, and comparing the identified amplitude signal with the signal after the outer loop amplitude correction to perform inner loop amplitude correction; identifying the phase difference between the synchronous controller signals, and compensating the phase difference using phase compensation technology; generating the driving signal of each vibration table by integrating the signal after the inner loop amplitude correction, the compensated phase and the sinusoidal signal source, so as to synchronize the vibration tables.

[0042] Preferably, the distance between the first-stage blade transducer and the last-stage blade transducer is smaller than the wavelength corresponding to the operating frequency of the low-frequency underwater fluid sound generating device, so as to avoid different transducers becoming coherent sound sources and to avoid mutual cancellation of sound wave energy generated by blade transducers of different stages.

[0043] Further preferably, the blade transducer includes: a blade structure and a driving structure; the blade structure is arranged on the central axis so that it is driven by the central axis while the central axis rotates and rotates around the central axis; the driving structure is arranged on the central axis and connected to the blade structure so as to drive the blade structure to produce periodic swing when excited.

[0044] Wherein, the blade structure includes: a blade seat and a blade group. The blade seat includes: a base and multiple branches; the base is a circular ring structure, which is sleeved on the outside of the central axis and fixedly connected to the central axis to rotate with the rotation of the central axis; multiple branch interval arrays are arranged on the outer ring of the base, and extend radially toward the outside of the base. The blade group includes: multiple blades arranged in an interval array on the blade seat, with one end of the blade connected to the blade seat as the root of the blade, and the other end of the blade as the tail of the blade; the number of blades is the same as that of branches and corresponds one to one, and the root of the blade is connected to the corresponding branch through a needle bearing (specifically, the needle bearing is arranged inside the root of the blade, and the inner ring of the needle bearing is sleeved on the outside of the corresponding branch to avoid rigid friction and make the rotation flexible), so that the blade rotates with the rotation of the central axis.

[0045] The driving structure includes: a permanent magnet, a coil, an adapter and a connecting rod. The permanent magnet is a circular ring structure, which is sleeved on the outside of the central axis and fixedly connected to the central axis so as to rotate with the rotation of the central axis; a circular ring groove is provided on one end of the permanent magnet close to the blade structure, and the radius of the circular ring groove is greater than the inner diameter of the permanent magnet and smaller than the outer diameter of the permanent magnet. The coil is a circular ring structure, part of which is arranged in the circular ring groove and connected to the permanent magnet; there is a gap between the coil and the central axis, and reciprocating vibration along the axial direction of the central axis is generated when power is turned on (how to turn on power is the prior art). There are multiple adapters, all of which are fixedly connected to the coil to be linked with the coil. The number of connecting rods and adapters is the same and corresponds one to one, and the number of connecting rods and blades is also the same and corresponds one to one; one end of the connecting rod is hingedly connected to the corresponding adapter, and the other end is hingedly connected to one side of the blade root of the corresponding blade, so that when the coil vibrates and drives the adapter to vibrate, the blade is driven to swing around the length direction of the blade.

[0046] The blade structure and the driving structure are linked with the central axis, avoiding the influence of the rotation and swing of the blades due to the generation of shear force, and improving the power and intensity of the sound wave radiation.

[0047] More preferably, the number of blades is 10 to 20, the length of the blade is 1 / 20 to 1 / 30 of the wavelength corresponding to the working frequency, the width of the blade root is the ratio of the circumference of the outer ring of the base to the number of blades, the thickness of the blade root is 1 / 15 to 1 / 20 of the blade length, the width of the blade tail is the ratio of the circumference of the inner ring of the duct to the number of blades, the thickness of the blade tail is 1 / 100 to 1 / 150 of the blade length, and the thickness of the blade decreases linearly from the blade root to the blade tail, so that the blade structure can fully interact with the fluid in the duct space and reduce the fluid resistance acting on a single The torque on the blades reduces the force applied by the water medium to the blades, increases the force strength of the frontal surface, ensures the structural strength of the blade group, avoids deformation or even breakage of the blades, and after the blade transducers are connected in series in multiple stages, it is possible to achieve higher sound intensity and sound wave power with smaller blades, smaller swing amplitude, and lower rotation speed, thereby improving the efficiency of low-frequency sound radiation, thereby reducing the volume of the low-frequency underwater fluid sound-generating device, reducing the cost, and overcoming the difficulty in the prior art that a larger blade size and blade area are required to produce high-efficiency, low-frequency, and high-power sound waves.

[0048] The working process of this embodiment is: 1) The underwater fuel in the fuel tank of the power assembly reacts chemically with water to generate a high-pressure fluid medium upstream of the nozzle, which is ejected through the nozzle and converted into a high-speed jet at the nozzle outlet.

[0049] 2) The high-speed jet formed by the power component impacts the turbine of the rotating component, driving the turbine to rotate, driving the central axis of the transducer component to rotate, and then driving the generator of the rotating component installed on the central axis to continuously generate and output electrical energy using the principle of electromagnetic induction, providing power for electronic components such as the synchronous controller, power amplifier and vibration displacement sensor of the transducer component.

[0050] 3) The rotation of the turbine of the rotating component drives the central axis of the transducer component to rotate, and then drives the blade structure installed on the central axis to rotate around the central axis; the power amplifier outputs an electrical signal of specific frequency and intensity to the drive structure, causing it to produce axial reciprocating vibration. The drive structure adopts the working principle of a vibration table (voice coil motor) to drive the blade structures of different levels of blade transducers to swing periodically at the same frequency and amplitude. The output displacement amplitude of the blade structure swing decreases rapidly with the increase of the vibration frequency; the rotation and periodic swing of the blade structure around the central axis jointly generate a fluid flow at the cylindrical duct outlet (blade side) whose flow rate changes periodically with time, thereby forming underwater low-frequency sound wave radiation.

[0051] 4) In theory, the rotation and swing of the blade structure in each level of blade transducer should meet the phase and amplitude consistency requirements. Considering the differences in processing and excitation control between blade transducers of different levels, the actual operation of the device may not meet the consistency under ideal conditions. Therefore, the vibration displacement sensor of the transducer assembly obtains the vibration signal output by the drive structure and outputs a multi-channel vibration displacement signal to the synchronization controller; the synchronization controller calculates the corrected excitation signal according to the synchronization control algorithm, regenerates the closed-loop feedback control signal, and inputs it to the power amplifier; the power amplifier outputs the control signal to adjust the vibration signal of the drive structure of the blade transducer to meet the consistency excitation requirements, and excites the drive structure of the blade transducer to produce axial periodic vibration, so as to achieve the synchronization and consistency of the swing of the blade structure in blade transducers of different levels.

[0052] Compared with the prior art, this application has the following advantages: 1. Compared with piezoelectric transducers, it can expand the response of transducers in low frequency / very low frequency bands, solving the problem of low source level or excessive volume and weight of conventional piezoelectric transducers in low frequency operation; 2. Compared with electric transducers, it can solve the contradiction between volume and weight, radiation area, vibration amplitude of the radiation surface and high power and high sound intensity in the low frequency band, and solve the bottleneck problem that the radiation sound intensity of conventional electric transducers decreases rapidly with the decrease of frequency; 3. Compared with the new blade-type transducer, the limitations of this type of transducer in terms of blade strength and blade swing drive displacement (blade swing amplitude) are removed. Theoretically, the sound intensity and sound power can be increased to any value, and the low frequency can be reduced to any value. It can not only take into account the requirements of wide bandwidth, large radiation area and vibration amplitude, controllable volume and weight required by the application, but also break through the bottleneck of sound intensity and sound power in the low frequency band and very low frequency band.

[0053] Therefore, the technical solution of the present application breaks through the technical bottlenecks of conventional low-frequency underwater acoustic transducers in terms of wide frequency band, low frequency lower limit, high sound intensity and high power. It is a subversion of low-frequency / very low-frequency underwater acoustic transducer technology and is expected to significantly enhance related underwater acoustic detection, environmental observation and underwater acoustic countermeasure capabilities.

[0054] The above-mentioned low-frequency underwater fluid sound-generating device uses a blade-type transducer as the basic sound-generating unit. By connecting low-frequency / very low-frequency blade-type transducers in multiple stages in series, centrally coaxially rotating and synchronously driving, the problem that the sound intensity and sound power of a single blade-type transducer cannot be improved due to insufficient strength of the blade structure itself and limited displacement of the blade swing drive is solved, and the consistency (synchronicity) of the swing of blade components at each level is achieved to superimpose the sound intensity and realize wide-band, high-power, high-intensity low-frequency sound radiation; by adding ducts to the periphery of the multi-stage blade-type transducer and introducing high-energy-density energy supplies such as fuel reactions, internal and external The mutual influence of fluid media further improves the low-frequency radiation efficiency; underwater chemical reactions are used instead of electrical energy to increase energy density and improve the compactness of the device; synchronous control is applied to blade transducers at each level, and a synchronous controller is used to obtain the blade swing drive displacement inside the blade transducer at each level and output a correction signal to the power amplifier. A synchronous control algorithm is used to complete the feedback control of the displacement, and the multi-level drive is controlled to achieve good consistency, avoiding the radiation signal effect caused by the difference in structure and excitation at each level; a power component, a rotating component and a transducer component are designed, and the three cooperate with each other. The rotation and swing of the blades change the blade angle of attack, thereby adjusting the flow generated by the blade movement, and under the drive of the power component, the sound generation efficiency is improved. That is to say, the present application generates sound by regulating the change of flow over time. The device itself does not contain structural vibration. The sound generation principle does not come from structural vibration, but the fluctuation of pressure and density generated when the fluid flow changes and the fluctuation is propagated in the form of sound waves. In principle, it overcomes the shortcomings of traditional low-frequency transducers under low-frequency and high-power conditions. The volume and vibration amplitude are limited; through the coordinated cooperation of the above-mentioned technical features, high-power low-frequency sound wave radiation can be efficiently generated in the underwater low-frequency / very low-frequency band. A low-frequency underwater fluid sound-generating device with wide bandwidth, high sound intensity, high power, large radiation area, high vibration amplitude of the radiation surface, economy, stability and reliability, and small volume and weight can be realized, and high-efficiency radiation in the low-frequency band can be achieved, which is suitable for practical applications, especially for scenarios such as underwater acoustic detection and confrontation (for example: in order to accurately simulate the low-frequency sound radiation of underwater operating equipment targets for long-distance detection, it is necessary to be close to the actual target in terms of both spectral characteristics and sound power, and the transducer is required to efficiently generate high-power sound wave energy in the frequency band below 300 Hz), which is expected to significantly improve the relevant underwater acoustic detection, environmental observation and underwater acoustic confrontation capabilities.

[0055] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0056] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A low-frequency underwater fluid sound-generating device, characterized in that: It includes: a power component, a rotating component and a transducer component connected in sequence; the transducer component includes: a central shaft and a multi-stage blade transducer connected in series on the central shaft; The power component converts the chemical energy of the fuel into the kinetic energy of the fluid to drive the rotating component; The rotating assembly rotates under the impact of the power assembly, and drives the central axis of the energy conversion assembly to rotate, so as to convert the fluid kinetic energy into mechanical kinetic energy; The blade transducer of the transducer assembly is linked with the central axis, so that the blade structure of the blade transducer rotates and swings, generating a water flow whose flow rate changes periodically with time, forming low-frequency sound radiation, so as to convert mechanical kinetic energy into sound energy and realize low-frequency underwater fluid sound generation.

2. A low-frequency underwater fluid sound generating device according to claim 1, characterized in that: The energy conversion assembly further includes: a duct; The duct is a cylindrical annular structure, which is sleeved at intervals on the outside of all blade-type transducers and is rotatably connected to the central shaft; One end of the central shaft is arranged at one end of the duct, and the other end passes through the other end of the duct and is connected to the rotating component.

3. A low-frequency underwater fluid sound generating device according to claim 2, characterized in that: The energy conversion component also includes: a synchronous controller, a power amplifier and a vibration displacement sensor; The synchronous controller adopts a synchronous control algorithm to calculate and obtain an excitation signal, and inputs the excitation signal to the power amplifier; The power amplifier outputs a control signal according to the excitation signal to excite the blade-type transducer to generate vibration; The vibration displacement sensor is connected to the blade transducer to obtain vibration information of the blade transducer, generate a vibration signal, and send it to the synchronization controller to correct the excitation signal; The synchronous controller, the power amplifier and the vibration displacement sensor work together to achieve synchronous driving and consistent excitation.

4. A low-frequency underwater fluid sound generating device according to claim 3, characterized in that: The synchronous control algorithm includes: outer loop control and inner loop control; The outer loop control includes: identifying and synthesizing the amplitude of the signal of the vibration displacement sensor and comparing it with the vibration reference signal to perform outer loop amplitude correction so that the response amplitude of the device is equal to the set vibration amplitude; The inner loop control includes: identifying the amplitude of the synchronous controller signal and comparing it with the signal obtained by the outer loop amplitude correction to perform inner loop amplitude correction; identifying and compensating the phase difference between the synchronous controller signals; and generating various drive signals by integrating the inner loop amplitude corrected signal, the compensated phase and the sinusoidal signal source to synchronize the vibration.

5. A low-frequency underwater fluid sound generating device according to any one of claims 1 to 4, characterized in that: The blade-type transducer comprises: a blade structure and a driving structure; The blade structure is arranged on the central shaft so as to rotate simultaneously with the rotation of the central shaft; The driving structure is connected to the blade structure so as to drive the blade structure to generate periodic swing when being excited.

6. A low-frequency underwater fluid sound generating device according to claim 5, characterized in that: The blade type transducer further comprises: an assembly bearing disposed on the central axis; The blade structure and the driving structure are both connected to the central shaft via the assembled bearing.

7. A low-frequency underwater fluid sound generating device according to any one of claims 1 to 4, characterized in that: The distance between the first-stage blade transducer and the last-stage blade transducer is smaller than the wavelength corresponding to the working frequency of the low-frequency underwater fluid sound-generating device.

8. A low-frequency underwater fluid sound generating device according to any one of claims 1 to 4, characterized in that: The rotating assembly includes: a turbine; The turbine is arranged on the central shaft so as to rotate under the impact of the power assembly and drive the central shaft to rotate.

9. A low-frequency underwater fluid sound generating device according to claim 8, characterized in that: The rotating assembly further includes: a generator connected to the turbine; The generator is disposed on the central shaft to generate electricity while the central shaft rotates.

10. A low-frequency underwater fluid sound generating device according to any one of claims 1 to 4, characterized in that: The power assembly includes: a fuel tank and a nozzle connected to the fuel tank; The underwater fuel in the fuel tank reacts chemically with water to generate a high-pressure fluid medium, which is ejected through the nozzle to form a high-speed jet.

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