Underwater vehicle stern noise reduction design method, acoustic metamaterial and underwater vehicle

Abstract

The invention provides an underwater vehicle stern noise reduction design method, an acoustic metamaterial and an underwater vehicle, and relates to the technical field of underwater vehicles, and the underwater vehicle stern noise reduction design method comprises the following steps: obtaining body noise generated when a propeller of the underwater vehicle works, the pulsating load generated by the propeller is transmitted to the shell through the shaft system or directly excites the shell to generate vibration information; the radiation noise of the stern shell is determined according to the vibration information; the target structure type and target characteristic parameters of the acoustic metamaterial are determined according to the body noise, the stern shell radiation noise and the to-be-controlled sound wave frequency band, and the reverse sound wave is obtained after the stern shell radiation noise is deflected by the acoustic metamaterial. According to the underwater vehicle stern noise reduction design method, the design parameters of the acoustic metamaterial can be determined, so that after the acoustic metamaterial is laid on the surface of the underwater vehicle stern shell, reverse sound waves and propeller body noise can be superposed to generate destructive interference, and the noise is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of underwater vehicles, and in particular to a design method for noise reduction of the stern of an underwater vehicle, an acoustic metamaterial, and an underwater vehicle. Background Art

[0002] With the in-depth exploration and utilization of marine resources worldwide, and the crucial role the ocean plays in national security strategies, the research and development of underwater vehicles has become a key area of technological competition among nations. Vibration and noise control is a crucial step in the design and manufacturing of these vehicles, directly impacting their stealth, accuracy, and overall operational effectiveness.

[0003] Propeller noise, one of the main noise sources for underwater vehicles, can be divided into hydrodynamic noise and propeller and hull vibration noise based on its generation mechanism. Propeller and hull vibration noise is the noise caused by the vibration of the propeller blades themselves, as well as the vibration noise transmitted to the hull through the shafting. With the continuous improvement of propeller design and vibration reduction technology, this noise has gradually become a significant factor in the radiated noise of underwater vehicles.

[0004] Therefore, there is a need for an efficient method to control and reduce the noise of the propeller and stern of underwater vehicles in various frequency bands to meet the noise reduction needs of modern underwater vehicles. Summary of the Invention

[0005] In view of this, the present application proposes a design method for noise reduction of the stern of an underwater vehicle, an acoustic metamaterial, and an underwater vehicle.

[0006] In a first aspect, the present application provides a method for designing noise reduction at the stern of an underwater vehicle. The method is applied to the structural design of an acoustic metamaterial, wherein the acoustic metamaterial is applied to the surface of the stern shell of the underwater vehicle. The method comprises: Acquire the body noise generated by the underwater vehicle propeller when it is working, as well as the vibration information generated by the pulsating load generated by the propeller transmitted to the shell through the shaft system or directly exciting the shell; determining the stern shell radiation noise according to the vibration information; The target structural type and target characteristic parameters of the acoustic metamaterial are determined based on the body noise, the stern shell radiation noise, and the frequency band of the sound wave to be controlled, so that the sound wave peaks of the body noise and the troughs of the reverse sound wave are at least partially offset, wherein the reverse sound wave is obtained by deflecting the stern shell radiation noise through the acoustic metamaterial.

[0007] In one embodiment, determining the stern shell radiation noise according to the vibration information includes: Based on the acoustic simulation method, the vibration-acoustic coupling process of the shell is simulated and a vibration-acoustic radiation coupling simulation model is constructed; Inputting the vibration information into the vibration-acoustic radiation coupling simulation model to obtain vibration response information of the stern shell; The stern shell radiation noise is determined according to the vibration response information.

[0008] In one embodiment, determining the target structure type and target characteristic parameters of the acoustic metamaterial based on the body noise, the stern shell radiation noise, and the sound wave frequency band to be controlled includes: Based on the frequency band of the sound wave to be controlled, filtering the body noise and the stern shell radiation noise to extract the body noise and the stern shell radiation noise within the frequency band of the sound wave to be controlled; Determining the target structure type of the acoustic metamaterial according to the filtered stern shell radiation noise; The target characteristic parameters of the acoustic metamaterial under the target structure type are determined according to the filtered body noise, the target structure type of the acoustic metamaterial, and the stern shell radiation noise.

[0009] In one embodiment, filtering the body noise and the stern shell radiation noise includes: Determine the target resistance range of the filter based on the frequency band of the noise to be controlled; The corresponding filter is controlled to operate at the target resistance gear, so that the filter performs filtering processing on the body noise and the stern shell radiation noise respectively.

[0010] In one embodiment, determining the target structure type of the acoustic metamaterial based on the filtered stern shell radiation noise includes: performing a spatial distribution analysis on the stern shell radiation noise to obtain a spatial distribution characteristic of the stern shell radiation noise; Determining the target structure type of the acoustic metamaterial according to the spatial distribution characteristics of the stern shell radiation noise; Determining target characteristic parameters of the acoustic metamaterial under the target structure type according to the filtered body noise, the target structure type of the acoustic metamaterial, and the stern shell radiation noise includes: The target characteristic parameters of the acoustic metamaterial are determined according to the phase of the body noise, the target structure type of the acoustic metamaterial, and the frequency, phase, and amplitude of the stern shell radiation noise.

[0011] In one embodiment, the target structure type is a periodic structure; the frequency of the stern shell radiation noise is inversely correlated with the characteristic size of the microstructure unit in the acoustic metamaterial; The phase difference between the reverse sound wave and the body noise is π.

[0012] In one embodiment, obtaining the body noise generated by the propeller of the underwater vehicle when it is in operation, and the vibration information generated by the pulsating load generated by the propeller being transmitted to the casing through the shaft system or directly exciting the casing, includes: The method comprises obtaining the body noise monitored by the hydroacoustic signal sensor and the vibration information monitored by the vibration signal sensor when the propeller of the underwater vehicle is in operation, wherein the propeller hydroacoustic signal sensor is arranged in the water area around the propeller, and the vibration signal sensor is installed on the stern shell of the underwater vehicle.

[0013] In one embodiment, before obtaining the body noise generated by the propeller of the underwater vehicle during operation and the vibration information generated by the pulsating load generated by the propeller being transmitted to the housing through the shaft system or directly exciting the housing, the method further includes: Acquiring the propeller position of the underwater vehicle and the structural characteristic information of the stern of the underwater vehicle; The propeller position of the underwater vehicle is set as the origin, and the placement position and number of the underwater acoustic signal sensors are determined according to the structural characteristics of the stern of the underwater vehicle.

[0014] In a second aspect, the present application further provides an acoustic metamaterial, which is applied on the surface of the stern shell of an underwater vehicle, and the structural type and characteristic parameters of the acoustic metamaterial are determined based on the underwater vehicle stern noise reduction design method as described in the first aspect.

[0015] In a third aspect, the present application further provides an underwater vehicle, comprising a vehicle shell, a propeller, and the acoustic metamaterial as described in the second aspect, wherein the acoustic metamaterial is applied on the surface of the stern shell of the underwater vehicle.

[0016] The present invention provides a method for designing a stern noise reduction system for an underwater vehicle, which has the following advantages over related technologies: 1. Because propeller noise and propeller-induced hull radiated noise share frequency components, acoustic metamaterials are applied to the surface of the underwater vehicle's stern hull. This deflects the hull radiated noise, superimposing it with the propeller noise to produce interference cancellation, thereby reducing noise from the propeller and stern of the underwater vehicle across various frequency bands. The present method for designing underwater vehicle stern noise reduction utilizes an acoustic metamaterial structure, enabling precise control of noise at specific frequencies. This significantly enhances the noise reduction effect compared to traditional noise reduction methods, adapts to different noise sources and characteristics, and provides an effective noise reduction solution for different underwater vehicle operating conditions.

[0017] 2. This application utilizes a rationally designed acoustic metamaterial applied to the hull surface of an underwater vehicle's stern. The metamaterial deflects the hull's radiated noise, superimposing it with the propeller noise to produce interference cancellation. This reduces noise across various frequency bands from the propeller and stern of the underwater vehicle. This improves the vehicle's stealth and safety, reduces the risk of detection by enemy sonar and other detection equipment, and minimizes interference with and damage to marine life. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of a flow chart of a method for designing noise reduction at the stern of an underwater vehicle in one embodiment of the present application; Figure 2 Schematic diagram of the structure of an underwater vehicle without acoustic metamaterials in one embodiment of the present application; Figure 3 This is a schematic structural diagram of an underwater vehicle equipped with acoustic metamaterials according to an embodiment of the present application; Figure 4 Schematic diagram of the frequency spectrum of the propeller body noise obtained after low-pass filtering in one embodiment of the present application; Figure 5 This is a fitted waveform diagram of the propeller body noise after low-pass filtering in one embodiment of the present application; Figure 6 This is a fitted waveform diagram of the stern shell radiation noise after low-pass filtering in one embodiment of the present application; Figure 7 This is a fitted waveform diagram of the reverse sound wave in one embodiment of the present application; Figure 8This is a synthetic noise waveform diagram under different phase differences between the propeller body noise and the reverse acoustic wave noise in one embodiment of the present application; Figure 9 Schematic diagram of the structure of the stern shell of the underwater vehicle and the acoustic metamaterial after the acoustic metamaterial is laid in one embodiment of the present application; Figure 10 Schematic diagram of the structure of the internal channel of the acoustic metamaterial in one embodiment of the present application. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0021] As mentioned in the background, propeller noise, a major source of noise for underwater vehicles, can be divided into hydrodynamic noise and propeller and hull vibration noise based on their generation mechanism. Propeller and hull vibration noise comprises the inherent noise caused by propeller blade vibration, as well as the vibration noise transmitted to the hull through the shafting. With the continuous advancement of propeller design and vibration reduction technology, this noise has become a significant contributor to the radiated noise of underwater vehicles.

[0022] Therefore, there is a need for a more efficient method that can control and reduce the noise of the propeller and stern of underwater vehicles in various frequency bands to meet the noise reduction needs of modern underwater vehicles.

[0023] Based on this, in some embodiments, such as Figure 1 As shown, the present application provides a method for designing a stern noise reduction system for an underwater vehicle. The method is applied to the structural design of an acoustic metamaterial, which is applied to the surface of the stern shell of the underwater vehicle. In the application, an underwater vehicle without acoustic metamaterial is Figure 2 As shown in FIG, the underwater vehicle comprises an underwater vehicle bow 1, an underwater vehicle middle 2, an underwater vehicle stern 3, and an underwater vehicle propeller 4. After the acoustic metamaterial is applied on the surface of the underwater vehicle stern shell, Figure 3 The underwater vehicle stern noise reduction design method includes the following steps S101 to S103.

[0024] S101: Obtain the body noise generated by the propeller of the underwater vehicle when it is in operation, as well as the vibration information generated by the pulsating load generated by the propeller transmitted to the shell through the shaft system or directly exciting the shell.

[0025] The vibration information may include parameters such as vibration frequency and amplitude.

[0026] During a vessel's voyage, the high-speed propellers disturb the stern fluid, generating unsteady excitation forces at the propeller. In the propeller-shaft-stern coupled system, propeller bearing forces are transmitted to the stern housing via the shafting, bearings, and foundation. The propeller surface forces act directly on the housing above the propeller, collectively causing vibration and acoustic radiation from the vehicle's housing. Furthermore, high-speed propeller operation also generates noise (sound waves directly generated by blade pressure pulsation and cavitation during propeller rotation).

[0027] S102: Determine the stern shell radiation noise based on the vibration information.

[0028] It's understood that the pulsating loads generated by the propeller are transmitted to the hull through the shafting or directly excite the hull, generating vibrations. The vibration of the aft hull is the primary factor contributing to the stern hull radiated noise, and the stern hull radiated noise is directly related to the vibration of the aft hull. Therefore, after determining the stern hull vibration information, the stern hull radiated noise can be determined based on this vibration information.

[0029] S103: Determine the target structure type and target characteristic parameters of the acoustic metamaterial based on the main noise, the stern hull radiated noise, and the frequency band of the sound wave to be controlled, so that the peaks of the main noise and the troughs of the reverse sound wave at least partially offset each other. The reverse sound wave is the stern hull radiated noise deflected by the acoustic metamaterial.

[0030] In applications, due to the propeller-shaft-stern coupling system, propeller noise and propeller-induced hull noise share frequency components. Therefore, using acoustic metamaterials to deflect hull-radiated noise allows the deflected reverse sound waves to superimpose with the propeller noise, resulting in destructive interference. This reduces noise across various frequency bands from the propeller and stern of the underwater vehicle. Based on this, the target structural type and characteristic parameters of the acoustic metamaterial are determined based on the main noise, stern hull-radiated noise, and the frequency band of the sound wave to be controlled, so that the peaks of the main noise and the troughs of the reverse sound wave at least partially offset each other.

[0031] It can be understood that the reverse sound wave is the noise radiated from the stern shell after being deflected by the acoustic metamaterial. The phase of the reverse sound wave needs to be opposite to that of the main body noise, and the sound wave frequency band to be controlled is the specific frequency band that needs to be controlled. Therefore, based on the characteristics of the propeller body noise and the stern shell radiation noise, combined with the sound wave frequency band to be controlled, the target structure type (such as periodic structure, etc.) and target characteristic parameters (such as unit size, material thickness, etc.) of the acoustic metamaterial can be determined. Through metamaterial design, the acoustic metamaterial deflects the shell radiation noise, generating a reverse sound wave with a phase opposite to that of the main body noise. This causes the sound wave peaks of the main body noise and the troughs of the reverse sound wave to at least partially overlap, and the noise energy is offset by the principle of destructive interference, achieving control of noise in a specific frequency band.

[0032] The above-mentioned underwater vehicle stern noise reduction design method can realize the structural design of acoustic metamaterials, can accurately control noise of specific frequencies, and has a significantly enhanced noise reduction effect compared to traditional noise reduction methods. It can adapt to different noise sources and noise characteristics, and can provide an effective noise reduction design solution under different operating conditions of the underwater vehicle. In addition, this application designs an acoustic metamaterial with a rational structure, applies the acoustic metamaterial to the surface of the underwater vehicle stern shell, and uses the acoustic metamaterial to deflect the direction of the shell radiation noise, superimposing it with the propeller noise to produce interference cancellation. It can reduce the noise of various frequency bands of the underwater vehicle propeller and stern, thereby improving the stealth and safety of the underwater vehicle, reducing its risk of being detected by enemy detection equipment such as sonar underwater, and reducing interference and damage to marine life. Moreover, the present application scheme is applicable to underwater vehicle stern structures of different shapes and sizes, and has strong adaptability. Different deflection paths and acoustic metamaterial laying methods can be designed according to any underwater vehicle stern shell structure, which greatly reduces the design time of underwater vehicle stern noise reduction.

[0033] In some embodiments, step S101, obtaining the body noise generated by the underwater vehicle propeller during operation, as well as vibration information generated by the propeller's pulsating load transmitted to the hull through the shafting or directly exciting the hull, includes the steps of obtaining the body noise monitored by an underwater vehicle propeller's hydroacoustic signal sensor and vibration information monitored by a vibration signal sensor during operation. The propeller hydroacoustic signal sensor is disposed in the water surrounding the propeller, and the vibration signal sensor is mounted on the stern hull of the underwater vehicle.

[0034] It can be understood that since the propeller body noise and the stern casing radiation noise are not separated, the detected noise signal is the noise signal after the propeller body noise and the stern casing radiation noise are superimposed, and the stern casing radiation noise signal cannot be distinguished alone. Therefore, the stern casing vibration signal sensor is used to monitor the pulsating load generated by the propeller transmitted to the casing through the shafting or directly excites the casing. The vibration information generated, and then the stern casing radiation noise is determined based on the vibration information.

[0035] In this application, after placing propeller hydroacoustic signal sensors in the waters near the propeller, the propeller's operating status and noise data can be monitored in real time. When the propeller is operating underwater, modulation occurs. The modulated propeller noise is a continuous spectrum, mainly concentrated in the low-frequency band, with periodic peaks. After detecting this noise signal, the hydroacoustic signal sensor can convert it into a charge signal. The stern hull vibration signal sensor can be placed on the inside and outside of the underwater vehicle's stern hull to ensure that the stern hull vibration can be accurately captured. During the collection process, the operating status of the equipment and the quality of the noise data are monitored in real time. If any anomalies or poor data quality are found, the equipment or collection parameters should be adjusted in a timely manner.

[0036] It should be noted that the charge signals monitored by the propeller hydroacoustic signal sensor and the vibration signal sensor can be amplified by a charge amplifier, and the charge signals can be converted into voltage signals, which can then be transmitted to a computer device so that the computer device can obtain the body noise monitored by the hydroacoustic signal sensor when the propeller of the underwater vehicle is working, as well as the vibration information monitored by the vibration signal sensor.

[0037] In some embodiments, before step S101, the underwater vehicle stern noise reduction design method also includes: obtaining the propeller position of the underwater vehicle and the structural characteristic information of the stern of the underwater vehicle; setting the propeller position of the underwater vehicle as the origin, and determining the deployment position and deployment quantity of the underwater acoustic signal sensor according to the structural characteristics of the stern of the underwater vehicle.

[0038] It can be understood that a spatial coordinate system is established with the propeller position as the coordinate origin. Based on the acoustic propagation characteristics of the stern structure (such as the vibration transmission path and the direction of sound wave radiation) and noise monitoring requirements, underwater acoustic signal sensors should be deployed in key locations such as the propeller near field, the vibration mode nodes / antinodes on the stern shell surface, and the direction of the main lobe of sound wave radiation. The number of sensors should be determined based on the structural complexity and measurement accuracy requirements (such as 4 to 8 measurement points evenly distributed along the circumference to cover the radial vibration of the shell, and 2 to 3 groups of measurement points arranged axially to monitor the noise attenuation pattern) to ensure that the sensor array can effectively capture the body noise. Therefore, after determining the structural characteristics of the underwater vehicle's stern, the placement location and number of underwater acoustic signal sensors can be determined based on the structural characteristics of the underwater vehicle to ensure measurement accuracy.

[0039] In some embodiments, in step S102, determining the stern shell radiation noise based on the vibration information includes: simulating the vibration-acoustic coupling process of the shell based on an acoustic simulation method to construct a vibration-acoustic radiation coupling simulation model; inputting the vibration information into the vibration-acoustic radiation coupling simulation model to obtain vibration response information of the stern shell; and determining the stern shell radiation noise based on the vibration response information.

[0040] It's understandable that the stern hull radiated noise is primarily caused by the operating conditions of the propeller-shaft-stern coupling system, which is induced by the rotating components of the propulsion system. This includes mechanical structural vibrations caused by factors such as unbalanced forces from the main propulsion motor, unbalanced couplings between the stern shaft system components, and misalignment. These vibrations are transmitted through specific support structures to the plate and shell structure at the interface between the carrier and the water. The surface vibrations of the plate and shell generate acoustic radiation, forming underwater radiated noise. Therefore, the vibrations generated by the shell contribute to the stern hull radiated noise. Simulation based on this vibration information can best simulate this process and thus determine the stern hull radiated noise.

[0041] In applications, acoustic simulation techniques (such as the finite element method and boundary element method) can be used to simulate the vibration-acoustic coupling process of the shell. By calculating parameters such as the shell surface vibration velocity and acceleration, combined with acoustic radiation theory, the characteristics of the noise radiated from the stern shell to the surrounding medium (such as the noise spectrum, sound pressure level distribution, etc.) can be predicted and determined, thereby accurately obtaining the stern shell radiation noise.

[0042] In some embodiments, in step S103, the target structure type and target characteristic parameters of the acoustic metamaterial are determined based on the body noise, the stern shell radiation noise and the sound wave frequency band to be controlled, including: filtering the body noise and the stern shell radiation noise based on the sound wave frequency band to be controlled to extract the body noise and the stern shell radiation noise within the sound wave frequency band to be controlled; determining the target structure type of the acoustic metamaterial based on the filtered stern shell radiation noise; and determining the target characteristic parameters of the acoustic metamaterial under the target structure type based on the filtered body noise, the target structure type of the acoustic metamaterial and the stern shell radiation noise.

[0043] Based on the frequency band of the sound wave to be controlled (e.g. low frequency band), the propeller body noise and the stern shell radiation noise are first filtered: the noise components in the target frequency band are extracted by filtering, and their spectral characteristics (such as peak frequency, energy distribution) and phase characteristics are analyzed. The propeller body noise spectrum obtained after low-pass filtering is shown in the figure below: Figure 4Subsequently, the design parameters of the acoustic metamaterial were determined based on the filtered body noise and the stern shell radiation noise. This ensured that the reverse sound wave it produced was 180° out of phase with the filtered noise, achieving destructive interference between the peaks and troughs, thus achieving noise reduction and controlling the noise in the target frequency band.

[0044] Noise reduction methods used in related technologies (such as biomimetic surfaces, advanced manufacturing processes, and high-strength, low-noise materials) have achieved significant results in reducing high-frequency noise. However, these methods also come with challenges such as high manufacturing costs, complex manufacturing steps, and long manufacturing cycles. Furthermore, these noise reduction technologies are less effective for low-frequency noise. Propeller low-frequency noise is a significant component of ship noise, particularly when the ship is traveling at medium to high speeds. This low-frequency noise can become the primary component of the ship's radiated noise. The propeller's motion causes turbulence in the water, and its radiated energy spectrum is primarily concentrated in the low-frequency range.

[0045] In this embodiment, since the propeller body noise is mainly concentrated in the low-frequency band, the sound wave frequency band to be controlled can be set to the low-frequency band, and the acoustic metamaterial is used to deflect the direction of the shell radiation noise, which is superimposed with the propeller noise to produce interference cancellation, thereby achieving noise reduction in the low-frequency band, thereby effectively reducing the noise in various frequency bands of the propeller and stern of the underwater vehicle.

[0046] In some embodiments, filtering the body noise and the stern shell radiation noise includes: determining the target resistance gear of the filter based on the noise frequency band to be controlled; controlling the corresponding filter to operate at the target resistance gear so that the filter filters the body noise and the stern shell radiation noise respectively.

[0047] In applications, the filter can have multiple resistance gears. By changing the resistance gear of the filter, the passband can be adjusted to select the noise frequency band to be controlled. On this basis, based on the noise frequency band to be controlled, the target resistance gear of the filter is determined according to the matching relationship between the frequency response characteristics of the filter and the target frequency band. Subsequently, by switching the filter to the target resistance gear, the filter filters the propeller body noise and the stern shell radiation noise respectively, which can filter out the noise components outside the target frequency band and retain the noise signal within the frequency band to be controlled. For example, if the target frequency band is a low frequency band, the filter parameters are adjusted to maintain low attenuation in this frequency range, and form high attenuation in other frequency bands, thereby providing accurate noise input for the subsequent reverse sound wave design of acoustic metamaterials.

[0048] It should be noted that, in other embodiments, if the frequency band of the noise to be controlled is other frequency bands, a filter of the corresponding frequency band may also be used for filtering. For example, for a high frequency band, a high-pass filter may also be used for filtering.

[0049] In some embodiments, determining the target structure type of the acoustic metamaterial based on the filtered stern shell radiated noise includes: performing a spatial distribution analysis on the stern shell radiated noise to obtain the spatial distribution characteristics of the stern shell radiated noise; and determining the target structure type of the acoustic metamaterial based on the spatial distribution characteristics of the stern shell radiated noise. Determining target characteristic parameters of the acoustic metamaterial under the target structure type based on the filtered body noise, the target structure type of the acoustic metamaterial, and the stern shell radiated noise includes: determining the target characteristic parameters of the acoustic metamaterial based on the phase of the body noise, the target structure type of the acoustic metamaterial, and the frequency, phase, and amplitude of the stern shell radiated noise.

[0050] It can be understood that by performing a spatial distribution analysis on the stern shell radiation noise, the direction of the radiation main lobe can be determined and identified. According to different distribution characteristics such as directional main lobe or full-surface uniform radiation, a local resonance type, a directional metamaterial array or a periodic / composite structure with a corresponding layout method can be selected as the target structure type. For example, taking the periodic structure as the target structure type, after obtaining the spatial distribution characteristics of the stern shell radiation noise, the laying position and arrangement direction of the acoustic metamaterial can be determined based on the spatial distribution characteristics of the stern shell radiation noise. If the noise source is concentrated on the left side of the stern, the metamaterial units are densely laid on the left shell surface, and the unit arrangement direction is adjusted to be perpendicular to the noise propagation direction to enhance the sound wave reflection and cancellation effect. If the noise is uniformly distributed in a ring shape, a ring array metamaterial is used, and the units are evenly arranged along the circumference of the shell to ensure that sound waves in all directions can be effectively controlled.

[0051] By combining the phase of the body noise as a compensation benchmark, the frequency (adjusting the resonator neck length, periodic structure lattice constant, etc.), phase (achieving a 180° phase difference through stiffness-mass ratio optimization) and amplitude (ensuring that the reverse wave amplitude reaches more than 80% of the original wave) of the shell noise are matched. Ultimately, the target characteristic parameters such as the geometric parameters and material properties of the metamaterial are determined to achieve effective offset of the noise peaks and reverse wave troughs.

[0052] Based on the noise fitting equation , and the propeller body noise fitting equation is obtained and the fitting equation of the stern shell radiation noise The waveforms of propeller body noise and tail shell simulated radiation noise are as follows: Figure 5 and Figure 6 shown.

[0053] Due to the existence of the propeller-shaft-stern coupling system, the noise of the propeller itself and the shell radiation noise caused by the propeller will have the same frequency component. According to the stern shell radiation noise selected in the same frequency band as the propeller body noise, the deflection path of the stern shell radiation noise is designed. The reverse sound wave fitting equation after deflection is: , the reverse sound wave waveform is as follows Figure 7 As shown. The noise amplitude p passing through the propeller body pr and the reverse acoustic wave amplitude p after deflection de The average sound energy density of the propeller body noise and the average sound energy density of the reverse sound wave can be obtained. The average sound energy density of the propeller body noise is: in, is the density of the acoustic medium, and c0 is the speed of sound in water.

[0054] The average sound energy density of the reverse sound wave is: According to the synthetic sound energy formula, the synthetic sound energy density is: in, is the phase difference between the reverse sound wave and the body noise. Based on the above formula, it can be found that the synthetic sound energy density of the propeller body noise and the reverse sound wave after deflection is mainly related to the phase difference between the two. When the phase difference is When the amplitude increases with the fluctuation amplitude, the noise reduction effect cannot be maximized. The synthetic noise waveform under different phase differences between the propeller body noise and the reverse acoustic noise is shown in the figure below. Figure 8 shown.

[0055] If the phase difference between the propeller body noise and the shell radiation noise is , it is necessary to design a metamaterial channel so that the phase difference after the shell noise is deflected is . Therefore, the phase of the body noise and the phase of the stern shell radiation noise are closely related to the structure of the acoustic metamaterial, and the phase difference between the reverse sound wave and the body noise is π. When the target structure type is a periodic structure, the frequency of the stern shell radiation noise is inversely correlated with the characteristic size of the microstructure unit in the acoustic metamaterial. In the application, a mapping model can be constructed between the relevant parameters (the phase of the body noise and the frequency, phase and amplitude of the stern shell radiation noise) and the characteristic parameters of the acoustic metamaterial. The relevant parameters are input into the mapping model to determine the characteristic parameters of the acoustic metamaterial. The mapping model can be a mathematical model or a deep learning model.

[0056] For example, Figure 9 and Figure 10As shown, the acoustic metamaterial includes a periodically arranged phase interference structure, the destructive interference structure includes two maze-type structures with different wave paths (the structures on both sides are arches with different wave paths), and the phase interference structure is composed of a carbon fiber plate 901, a carbon fiber support plate 902, a carbon fiber baffle 903, and an underwater vehicle surface 904. The design parameters of the acoustic metamaterial are closely related to the noise parameters collected by the front end and need to be dynamically adjusted based on the collected data. The noise frequency determines the characteristic size of the metamaterial unit. The higher the frequency, the shorter the wavelength, the smaller the cavity volume, and the greater the period density. When processing low-frequency noise, the metamaterial unit size needs to be - , where λ is the noise wavelength. When the noise frequency is 100 Hz, the metamaterial unit size needs to be 0.75-1.5 m. The phase difference is achieved by adjusting the channel path difference to achieve the sound wave deflection cancellation. , making the sound wave propagation time difference , corresponding to the phase difference , when the noise frequency f=500Hz and the speed of sound in water c0=1500m / s, then =1.5m, the length difference of the channels on both sides needs to be designed to be 1.5m.

[0057] It should be noted that the interior of the destructive interference mechanism is a curved channel with a constant cross-section. The channel can deflect the propagation direction of the stern shell radiation noise. After deflection, the reverse noise is different from the propeller body noise. Approximately equal to or equal to -1, so that the peak of the propeller body noise wave and the trough of the reverse sound wave after deflection are partially offset or completely offset.

[0058] In some embodiments, the present application further provides an acoustic metamaterial, which is applied to the surface of the stern shell of an underwater vehicle. The structural type and characteristic parameters of the acoustic metamaterial are determined based on the underwater vehicle stern noise reduction design method of any of the above schemes.

[0059] For example, Figure 9 and Figure 10 As shown, the acoustic metamaterial may include a periodically arranged phase interference structure, wherein the destructive interference structure includes two maze-like structures with different wave paths (the structures on both sides are arches with different wave paths). The phase interference structure may include a carbon fiber plate 901, a carbon fiber support plate 902, a carbon fiber baffle 903, and an underwater vehicle surface 904. The design parameters of the acoustic metamaterial are determined based on the underwater vehicle stern noise reduction design method described in any of the above solutions.

[0060] The structural type and characteristic parameters of the above-mentioned acoustic metamaterial are determined based on the noise reduction design method for the stern of an underwater vehicle in any of the above schemes. Therefore, the acoustic metamaterial is applied to the surface of the stern shell of the underwater vehicle. The reverse sound waves obtained by deflecting the shell radiation noise using the acoustic metamaterial will be superimposed on the propeller noise, thereby generating interference cancellation, which can reduce the noise in various frequency bands of the propeller and stern of the underwater vehicle.

[0061] In some embodiments, the present application further provides an underwater vehicle, which includes a vehicle shell, a propeller, and an acoustic metamaterial according to any of the above schemes, wherein the acoustic metamaterial is applied on the surface of the stern shell of the underwater vehicle.

[0062] Among them, Figure 3 As shown, the vehicle shell can be divided into an underwater vehicle bow 1, an underwater vehicle middle 2, an underwater vehicle stern 3, and an underwater vehicle propeller 4. Acoustic metamaterial 31 is applied on the shell surface of the underwater vehicle stern 3.

[0063] Since the above-mentioned underwater vehicle adopts the acoustic metamaterial 31 of any of the above solutions and is applied to the surface of the hull of the stern 3 of the underwater vehicle, the noise of the propeller 4 and the stern of the underwater vehicle in various frequency bands is relatively low, thereby improving the concealment and safety of the underwater vehicle, reducing the risk of detection by enemy sonar and other detection equipment underwater, and reducing interference and damage to marine life.

[0064] In some embodiments, the present application further provides a device for designing a stern noise reduction system for an underwater vehicle, comprising: a propeller acoustic signal sensor, a vibration signal sensor, and a processing module. The propeller acoustic signal sensor is disposed in the water surrounding the propeller, the vibration signal sensor is mounted on the stern hull of the underwater vehicle, and the processing module is configured to execute any of the above-described methods for designing a stern noise reduction system for an underwater vehicle.

[0065] It should be noted that the underwater vehicle stern noise reduction design device provided in the embodiment of the present application and the underwater vehicle stern noise reduction design method provided in the embodiment of the present application are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned underwater vehicle stern noise reduction design method, and the repeated parts will not be repeated.

[0066] In some embodiments, an electronic device provided by an embodiment of the present application includes a processor and a memory; the memory stores a computer program, wherein the computer program implements the above-mentioned underwater vehicle stern noise reduction design method when executed by the processor.

[0067] Specifically, the processor may include, for example, a general-purpose microprocessor, an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor may also include onboard memory for caching purposes. The processor may be a single processing unit or multiple processing units for executing different actions of the method flow according to the embodiments of the present application.

[0068] Memory, for example, can be any medium capable of containing, storing, conveying, propagating, or transmitting instructions. For example, memory can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, components, or propagation media. Specific examples of memory include: magnetic storage devices, such as magnetic tape or hard disk drives (HDDs); optical storage devices, such as compact discs (CD-ROMs); random access memory (RAM) or flash memory; and / or wired or wireless communication links.

[0069] This application also provides a computer-readable medium storing a computer program that, when executed by a processor, implements the aforementioned method for designing a stern noise reduction system for an underwater vehicle. This computer-readable medium may be included in the device / apparatus / system described in the aforementioned embodiments, or it may exist independently and not incorporated into the device / apparatus / system. The computer-readable medium carries one or more programs that, when executed, implement the method described in the embodiments of this application.

[0070] According to an embodiment of the present application, a computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium or any combination thereof. A computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or component, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device, or component. In the present application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries computer-readable program code. Such a propagated data signal may take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical cable, radio frequency signals, or any suitable combination thereof.

[0071] Those skilled in the art will understand that the features described in the various embodiments and / or claims of the present application may be combined and / or combined in a variety of ways, even if such combinations or combinations are not explicitly described in the present application. In particular, without departing from the spirit and teachings of the present application, the features described in the various embodiments and / or claims of the present application may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present application. Therefore, the scope of the present application should not be limited to the above-mentioned embodiments, but should be determined not only by the attached claims, but also by the equivalents of the attached claims. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for designing noise reduction at the stern of an underwater vehicle, characterized in that: The underwater vehicle stern noise reduction design method is applied to the structural design of an acoustic metamaterial, wherein the acoustic metamaterial is applied to the surface of the stern shell of the underwater vehicle; the method comprises: Acquire the body noise generated by the underwater vehicle propeller when it is working, as well as the vibration information generated by the pulsating load generated by the propeller transmitted to the shell through the shaft system or directly exciting the shell; determining the stern shell radiation noise according to the vibration information; The target structural type and target characteristic parameters of the acoustic metamaterial are determined based on the body noise, the stern shell radiation noise, and the frequency band of the sound wave to be controlled, so that the sound wave peaks of the body noise and the troughs of the reverse sound wave are at least partially offset, wherein the reverse sound wave is obtained by deflecting the stern shell radiation noise through the acoustic metamaterial.

2. The method for designing noise reduction of the stern of an underwater vehicle according to claim 1, wherein: The determining the stern shell radiation noise according to the vibration information includes: Based on the acoustic simulation method, the vibration-acoustic coupling process of the shell is simulated and a vibration-acoustic radiation coupling simulation model is constructed; Inputting the vibration information into the vibration-acoustic radiation coupling simulation model to obtain vibration response information of the stern shell; The stern shell radiation noise is determined according to the vibration response information.

3. The method for designing noise reduction at the stern of an underwater vehicle according to claim 1, wherein: The step of determining the target structural type and target characteristic parameters of the acoustic metamaterial according to the body noise, the stern shell radiation noise, and the sound wave frequency band to be controlled includes: Based on the frequency band of the sound wave to be controlled, filtering the body noise and the stern shell radiation noise to extract the body noise and the stern shell radiation noise within the frequency band of the sound wave to be controlled; Determining the target structure type of the acoustic metamaterial according to the filtered stern shell radiation noise; The target characteristic parameters of the acoustic metamaterial under the target structure type are determined according to the filtered body noise, the target structure type of the acoustic metamaterial, and the stern shell radiation noise.

4. The method for designing noise reduction at the stern of an underwater vehicle according to claim 3, wherein: The filtering process of the body noise and the stern shell radiation noise includes: Determine the target resistance range of the filter based on the frequency band of the noise to be controlled; The corresponding filter is controlled to operate at the target resistance gear, so that the filter performs filtering processing on the body noise and the stern shell radiation noise respectively.

5. The method for designing noise reduction at the stern of an underwater vehicle according to claim 3, wherein: The determining the target structure type of the acoustic metamaterial according to the filtered stern shell radiation noise includes: performing a spatial distribution analysis on the stern shell radiation noise to obtain a spatial distribution characteristic of the stern shell radiation noise; Determining the target structure type of the acoustic metamaterial according to the spatial distribution characteristics of the stern shell radiation noise; Determining target characteristic parameters of the acoustic metamaterial under the target structure type according to the filtered body noise, the target structure type of the acoustic metamaterial, and the stern shell radiation noise includes: The target characteristic parameters of the acoustic metamaterial are determined according to the phase of the body noise, the target structure type of the acoustic metamaterial, and the frequency, phase, and amplitude of the stern shell radiation noise.

6. The method for designing noise reduction at the stern of an underwater vehicle according to claim 5, wherein: The target structure type is a periodic structure; the frequency of the stern shell radiation noise is inversely correlated with the characteristic size of the microstructure unit in the acoustic metamaterial; The phase difference between the reverse sound wave and the body noise is π.

7. The method for designing noise reduction at the stern of an underwater vehicle according to claim 1, wherein: The method of obtaining the body noise generated by the propeller of the underwater vehicle when it is in operation, and the vibration information generated by the pulsating load generated by the propeller being transmitted to the shell through the shaft system or directly exciting the shell, includes: The method comprises obtaining the body noise monitored by the hydroacoustic signal sensor and the vibration information monitored by the vibration signal sensor when the propeller of the underwater vehicle is in operation, wherein the propeller hydroacoustic signal sensor is arranged in the water area around the propeller, and the vibration signal sensor is installed on the stern shell of the underwater vehicle.

8. The method for designing noise reduction at the stern of an underwater vehicle according to claim 7, wherein: Before obtaining the body noise generated by the propeller of the underwater vehicle during operation and the vibration information generated by the pulsating load generated by the propeller being transmitted to the housing through the shaft system or directly exciting the housing, the method further includes: Acquiring the propeller position of the underwater vehicle and the structural characteristic information of the stern of the underwater vehicle; The propeller position of the underwater vehicle is set as the origin, and the placement position and number of the underwater acoustic signal sensors are determined according to the structural characteristics of the stern of the underwater vehicle.

9. An acoustic metamaterial, characterized in that: The acoustic metamaterial is applied on the surface of the stern shell of the underwater vehicle, and the structural type and characteristic parameters of the acoustic metamaterial are determined based on the underwater vehicle stern noise reduction design method according to any one of claims 1 to 8.

10. An underwater vehicle, characterized in that: The underwater vehicle comprises a vehicle shell, a propeller, and the acoustic metamaterial according to claim 9, wherein the acoustic metamaterial is applied on the surface of the stern shell of the underwater vehicle.

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