An underwater mechanical low-frequency noise generating device

Abstract

The present invention discloses an underwater mechanical low-frequency noise generating device, comprising a low-frequency generating propeller, a low-speed power motor and at least one flow disruptor, wherein the low-frequency generating propeller is installed at the shaft extension end of the low-speed power motor and fixed by a locking nut; the flow disruptor is arranged on a housing on the low-speed power motor close to one side of the low-frequency generating propeller, and the flow disruptor is parallel to the propeller disk of the low-frequency generating propeller; a motor controller is installed at the tail end of the low-speed power motor through a static seal, and the motor controller adopts a watertight joint to transmit data with a carrying platform, and is used to adjust the speed of the low-speed power motor to realize low-frequency frequency control. The present invention can be applied to the simulation of underwater low-frequency noise signals, avoiding complex electro-acoustic conversion structures and reducing the size and weight of the overall device.

Description

Technical Field

[0001] The invention belongs to the field of underwater acoustic technology, and in particular relates to an underwater mechanical low-frequency noise generating device. Background Art

[0002] The application demand for underwater low-frequency sound sources is very extensive and urgent, especially in the accurate simulation of targets. However, the generation and control of low-frequency characteristic sound sources is a technical bottleneck and a common problem that has attracted great attention in related fields at home and abroad.

[0003] At present, the industry mainly relies on hydroacoustic transducers to simulate the noise spectrum characteristics of various types of ships and boats to achieve the purpose of detection, identification, and interference confrontation. Conventional hydroacoustic transducers obtain noise spectra through pre-recording or numerical calculation, and then use electrostrictive effect and piezoelectric effect to generate noise of specific frequency through digital circuit processing. This method simulates the frequency controllability and continuity of noise, and can simulate the noise spectrum characteristics under various working conditions from starting, speed change to stable navigation, but it faces technical bottlenecks in the simulation of low-frequency noise (below 100Hz). Generally speaking, the lower the frequency and the greater the working water depth, the more difficult it is to design the hydroacoustic transducer. This is because in order to achieve the simulation of low-frequency noise, the size and weight of the device are large, and the space and energy supply capacity of the carrying platform are limited, forming a prominent contradiction; in addition, the performance of the device is also restricted by water pressure and temperature when used underwater.

[0004] Some types of underwater acoustic ring transducers that can currently achieve low-frequency noise emission are as follows:

[0005]

[0006]

[0007] Current underwater acoustic transducers have problems such as being restricted by size and weight under low-frequency limitations, complex structures, high costs, and significant impacts of working water depth and temperature on performance.

[0008] The impact of underwater environment on the performance of underwater acoustic transducers is mainly caused by two aspects: hydrostatic pressure and temperature. Hydrostatic pressure will cause changes in the electromechanical properties of transducer materials, the acoustic and mechanical properties of passive materials, the stress-strain characteristics of structural materials, and the electrical properties of electrical components. Under different hydrostatic pressures, underwater acoustic transducers will have different electroacoustic performances; temperature changes caused by depth will cause changes in transducer impedance, capacitance and other properties, resulting in mismatch with circuit components.

[0009] In addition, the "online" test of deep-water transducers is also limited by test conditions. The normal pressure water tank can only test the performance of the transducer at a depth of several meters. It can only perform high static pressure water pressure tests to verify whether there is any damage in deep water, but it is impossible to obtain the actual performance in deep water. Summary of the invention

[0010] The present invention provides an underwater mechanical low-frequency noise generating device, which can be applied to the simulation of underwater low-frequency noise signals, avoids the complex electro-acoustic conversion structure, and reduces the size and weight of the overall device.

[0011] The technical solution of the present invention is as follows:

[0012] An underwater mechanical low-frequency noise generating device comprises a low-frequency generating propeller, a low-speed power motor and at least one flow disruptor, wherein the low-frequency generating propeller is mounted on the shaft extension end of the low-speed power motor and fixed by a locking nut; the flow disruptor is arranged on a housing of the low-speed power motor close to one side of the low-frequency generating propeller, and the flow disruptor is parallel to the propeller disc of the low-frequency generating propeller;

[0013] A motor controller is installed at the tail end of the low-speed power motor through a static seal. The motor controller uses a watertight joint to transmit data with the mounting platform to adjust the speed of the low-speed power motor and realize low-frequency control.

[0014] The present invention can establish a theoretical model of the low-frequency line spectrum noise excitation source based on the existing noise spectrum through hydrodynamic numerical simulation of turbulent flow excitation and blade fluid dynamic response, obtain corresponding flow disruptor and blade profile design parameters, and add a low-speed power motor to achieve specific low-frequency noise, avoiding complex electro-acoustic conversion structure.

[0015] In the above technical solution, the low-speed power motor is used to provide power, and a flow disruptor is used to disturb the inlet flow field of the low-frequency generating propeller, so that low-frequency noise is generated by the rotating impeller of the low-frequency generating propeller.

[0016] Optionally, a low-speed power motor with a mechanical seal can be used, or it can be replaced with a shielded motor, a magnetic fluid sealed motor, a pressure balanced motor with a built-in water pressure or oil pressure circulation lubrication and filtration device and a diaphragm compensation balance, etc., which are motor solutions that can be used in deep water.

[0017] Optionally, a single, static inflow disruptor may be used, or it may be replaced by a number of active inflow disruptors to achieve a flow field that disturbs the propeller inflow.

[0018] Alternatively, the low frequency generating paddles may be replaced with other specially designed rotating machinery to achieve the generation of specific low frequency noise.

[0019] Furthermore, the distance between the incoming flow disruptor and the propeller disk of the low-frequency generating propeller is not greater than 0.1D, where D is the diameter of the low-frequency generating propeller.

[0020] Furthermore, the low-speed power motor is provided with a pair of angular thrust bearings for bearing the thrust generated by the rotation of the low-frequency generator propeller.

[0021] Furthermore, the static seal of the shell of the low-speed power motor adopts an O-ring form, and the rotary seal at the shaft extension adopts a mechanical seal form, which is used to achieve deep underwater operation.

[0022] Furthermore, a water-lubricated bearing is installed at the shaft extension end of the low-speed power motor to support the main shaft of the low-speed power motor.

[0023] Furthermore, the operating frequency of the underwater mechanical low-frequency noise generating device is determined by the rotation speed of the low-speed power motor and the number of blades of the low-frequency generating propeller, that is, the operating frequency = motor rotation speed × number of blades.

[0024] Furthermore, the maximum sound source level of the underwater mechanical low-frequency noise generating device is determined by the blade profile design parameters of the incoming flow disruptor and the low-frequency generating propeller, specifically:

[0025] According to the existing noise spectrum, through hydrodynamic numerical simulation of turbulent flow excitation and blade fluid dynamic response, a theoretical model of low-frequency line spectrum noise excitation source is established, and the corresponding blade profile design parameters of flow disruptor and low-frequency generating propeller are obtained.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) Conventional hydroacoustic transducers obtain noise spectra by pre-recording or numerical calculation, and then process them through digital circuits, and then use electrostrictive effect and piezoelectric effect to generate noise of specific frequency. The present invention, based on the existing noise spectrum, establishes a theoretical model of low-frequency line spectrum noise excitation source through hydrodynamic numerical simulation of turbulent flow excitation and blade fluid dynamic response, obtains corresponding flow disruptor and blade profile design parameters, and adds a low-speed power motor to achieve specific low-frequency noise, avoiding complex electro-acoustic conversion structure, reducing the size and weight of the overall device, and the component preparation cost of the present invention is low.

[0028] (2) When conventional hydroacoustic transducers work at great depths, their performance is affected by temperature and pressure. The flow disruptor and blades of the present invention do not need to be sealed, the motor sealing technology is relatively mature, and the low-frequency noise generation mechanism has little to do with water pressure and temperature, so it can work at great depths; and the performance indicators obtained at conventional water depths are basically consistent with deep-water performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure is a schematic diagram of the overall structure of an underwater mechanical low-frequency noise generating device of the present invention.

[0030] In the figure: 1- low frequency generating propeller; 2- flow disruptor; 3- low speed power motor; 4- motor controller; 5- watertight joint; 6- locking nut; 7- water-lubricated bearing; 8- mechanical seal; 9- angular thrust bearing. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0032] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "include" or "comprise" and the like used in the present invention mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The words "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0033] The current underwater acoustic transducer has problems such as size and weight constraints under low frequency limit, complex structure, high cost, and great influence of working water depth and temperature on performance. The present invention is based on the noise mechanism of propellers, pump jets and other thrusters, and uses mechanical methods to generate and simulate low-frequency noise. It is a brand-new technical approach, and the basic principle is completely different from the conventional underwater acoustic transducer sound-to-electric conversion mode.

[0034] like Figure 1 As shown, an underwater mechanical low-frequency noise generating device includes a low-frequency generating propeller 1, a flow disruptor 2 and a low-speed power motor 3.

[0035] The incoming flow disruptor 2 is arranged on the outer casing of the low-speed power motor 3, and the low-frequency generating paddle 1 is installed on the shaft extension end of the low-speed power motor 3 and fixed with a locking nut 6; the incoming flow disruptor 2 is parallel to the paddle disc surface of the low-frequency generating paddle 1, and the spacing is not greater than 0.1D, where D is the diameter of the low-frequency generating paddle 1.

[0036] The low-speed power motor 3 is provided with a pair of angular thrust bearings 9, which can withstand the thrust generated by the rotation of the propeller; the static seal of the motor housing adopts an O-ring form, and the rotating seal at the shaft extension adopts a mechanical seal 8 form, which can realize deep underwater operation.

[0037] A water-lubricated bearing 7 is installed at the shaft extension to support the main shaft of the low-speed power motor 3; the motor controller 4 is installed at the other end of the motor with a static seal, and a watertight joint 5 is used to transmit data with the mounting platform to adjust the motor speed and achieve controllable low-frequency.

[0038] The present invention is powered by a low-speed power motor 3, uses an incoming flow disruptor 2 to disturb the propeller inflow flow field, and generates low-frequency noise by rotating the impeller.

[0039] The working frequency of the underwater mechanical low-frequency noise generating device of the present invention is determined by the motor speed and the number of blades, that is, the working frequency=motor speed×number of blades.

[0040] The maximum sound source level of the underwater mechanical low-frequency noise generating device of the present invention is determined by the design parameters of the incoming flow disruptor and the blade profile of the propeller.

[0041] Conventional hydroacoustic transducers obtain noise spectra by pre-recording or numerical calculation, and then use the electrostrictive effect and piezoelectric effect to generate noise of specific frequency after being processed by digital circuits. The present invention, based on the existing noise spectrum, establishes a theoretical model of low-frequency line spectrum noise excitation source through hydrodynamic numerical simulation of turbulent flow excitation and blade fluid dynamic response, obtains corresponding flow disruptor and blade blade design parameters, and can achieve specific low-frequency noise by adding a low-speed power motor, avoiding complex electro-acoustic conversion structure, reducing the size and weight of the overall device, and the component preparation cost of the present invention is low.

[0042] When conventional hydroacoustic transducers work at great depths, their performance is affected by temperature and pressure. The flow disruptor and blades of the present invention do not need to be sealed, the motor sealing technology is relatively mature, and the low-frequency noise generation mechanism has little to do with water pressure and temperature, so it can work at great depths; and the performance indicators obtained at conventional water depths are basically consistent with deep water performance.

[0043] In the embodiment of the present invention, a mechanically sealed power motor is used. In actual applications, shielded motors, magnetic fluid sealed motors, pressure balanced motors with built-in water pressure or oil pressure circulation lubrication and filtration devices and diaphragm compensation balance, etc., which are motor solutions that can be used in deep water, can also be used.

[0044] In the embodiment of the present invention, a single static flow disruptor is used. In actual applications, it can be replaced by a number of active flow disruptors to achieve the flow field of the disturbed impeller inlet flow.

[0045] In the embodiment of the present invention, a propeller with a specially designed blade shape is used. In actual applications, it can be replaced by other specially designed rotating machinery to achieve the generation of specific low-frequency noise.

[0046] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An underwater mechanical low-frequency noise generating device, It is characterized in that The invention comprises a low-frequency generating propeller (1), a low-speed power motor (3) and at least one inflow disruptor (2), wherein the low-frequency generating propeller (1) is mounted on the shaft extension end of the low-speed power motor (3) and fixed by a locking nut (6); the inflow disruptor (2) is arranged on a housing of the low-speed power motor (3) close to one side of the low-frequency generating propeller (1), and the inflow disruptor (2) is parallel to the propeller disc surface of the low-frequency generating propeller (1); A motor controller (4) is installed at the tail end of the low-speed power motor (3) through a static seal, and the motor controller (4) uses a watertight joint (5) to transmit data with the mounting platform, so as to adjust the speed of the low-speed power motor (3) and realize low-frequency control; The maximum sound source level of the underwater mechanical low-frequency noise generating device is determined by the blade profile design parameters of the incoming flow disruptor (2) and the low-frequency generating propeller (1), specifically: According to the existing noise spectrum, through the hydrodynamic numerical simulation of turbulent flow excitation and blade fluid dynamic response, a theoretical model of the low-frequency line spectrum noise excitation source is established, and the corresponding blade profile design parameters of the flow disruptor (2) and the low-frequency generating propeller (1) are obtained.

2. The underwater mechanical low-frequency noise generating device according to claim 1, It is characterized in that The distance between the incoming flow disruptor (2) and the propeller disk surface of the low-frequency generating propeller (1) is no greater than 0.1D, where D is the diameter of the low-frequency generating propeller (1).

3. The underwater mechanical low-frequency noise generating device according to claim 1, It is characterized in that The low-speed power motor (3) is provided with a pair of angular thrust bearings (9) for bearing the thrust generated by the rotation of the low-frequency generating propeller (1).

4. The underwater mechanical low-frequency noise generating device according to claim 1, It is characterized in that The static seal of the shell of the low-speed power motor (3) is in the form of an O-ring, and the rotary seal at the shaft extension is in the form of a mechanical seal (8), which is used to achieve deep underwater operation.

5. The underwater mechanical low-frequency noise generating device according to claim 1, It is characterized in that A water-lubricated bearing (7) is installed at the shaft extension end of the low-speed power motor (3) to support the main shaft of the low-speed power motor (3).

6. The underwater mechanical low-frequency noise generating device according to claim 1, It is characterized in that The low-speed power motor (3) is used to provide power, and an incoming flow disruptor (2) is used to disturb the inflow flow field of the low-frequency generating propeller (1), so that low-frequency noise is generated through the rotating impeller of the low-frequency generating propeller (1).

7. The underwater mechanical low-frequency noise generating device according to claim 1, It is characterized in that The operating frequency of the underwater mechanical low-frequency noise generating device is determined by the rotation speed of the low-speed power motor (3) and the number of blades of the low-frequency generating propeller (1), that is, the operating frequency = motor rotation speed × number of blades.

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