Multi-section arc coupled high-power deep-sea giant magnetostrictive shrinkage acoustic transducer and design method thereof

Abstract

The invention provides a multi-section arc coupled high-power deep-sea giant magnetostrictive ultrasonic transducer and a design method thereof. The multi-section arc coupled high-power deep-sea giant magnetostrictive ultrasonic transducer comprises a multi-arc radiation shell, the two ends of the multi-arc radiation shell in the length direction are arc shells, and the side faces of the two ends of the multi-arc radiation shell in the width direction are multi-section arc shells. The multi-arc radiation shell is symmetrically arranged along the middle axis in the length direction and the middle axis in the width direction; the middle of the multi-section arc shell is a protruding arc-shaped part protruding outwards, and the two sides of the middle arc-shaped part are inwards-concave arc-shaped parts which are tangent to the middle arc-shaped part and concave inwards. An upper cover plate covers the upper portion of the multi-arc type radiation shell, a lower cover plate covers the lower portion of the multi-arc type radiation shell, and a driving module is installed in the multi-arc type radiation shell. According to the invention, by adopting the multi-arc shell, more effective modes can be created, so that the working bandwidth of the transducer is increased; in addition, the arc of the concave-convex structure can reduce the sensitivity of the surface stress of the transducer along with the change of water depth, so that the transducer can work in a deeper sea area.

Description

Technical Field

[0001] The invention belongs to the technical field of acoustic sensors, and mainly relates to a high-power deep-sea giant magnetostrictive underwater acoustic transducer with multi-segment circular arc coupling. Background Art

[0002] So far, sound waves are still the only energy carrier known to mankind that can be transmitted over long distances underwater. Using sound waves, people can complete tasks in the military and marine development fields underwater. Military applications include underwater tracking, submarine detection, target identification and communication, while civilian applications include offshore oil and gas resource exploration, ocean mapping, and seabed topography imaging.

[0003] The ocean is located at the forefront of national defense and is an important barrier to maintaining national security. Underwater communication and monitoring is one of the most important and critical technologies in current marine military affairs. It is the core support for building all-round ocean monitoring, underwater long-distance information transmission, and seabed resource exploration. Therefore, the faster development and research of corresponding hydroacoustic equipment and technology is of great significance to safeguarding my country's marine rights and interests and building a maritime power.

[0004] At the same time, with the development of manned submersibles, new challenges and requirements have been put forward for related deep-sea hydroacoustic equipment, especially the demand for hydroacoustic transducers as the transmitting end of active sonar systems has become more urgent. As one type of hydroacoustic transducers, flextensional transducers are of great significance for research.

[0005] Generally speaking, deep-sea transducers usually use pressure compensation or overflow structures. However, for flex-tensional transducers, the overflow structure will greatly reduce the electroacoustic efficiency. Pressure compensation, such as oil filling, compressed gas injection, and compliant tube filling, will add additional structures to the transducer, reduce the electroacoustic efficiency, and have a greater test on the reliability under deep-sea operation. Currently, the most commonly used type IV flex-tensional transducer has an elliptical cylinder protruding on both sides. It achieves high sound source level output by amplifying the displacement on the short axis to the displacement on the long axis. However, the IV type transducer has an inherent defect, that is, as the working water depth increases, the shell will gradually expand under the influence of hydrostatic pressure, resulting in the release of the prestress on the rod. Although it can be adjusted to a certain extent by multi-pressure prestressing in the air, it is basically unrealistic to work in the deep sea. Another type of VII flextensional transducer has the opposite characteristics to type IV. Its shell is compressed as the water depth decreases, that is, the prestress of the drive unit increases with the water depth. The 900Hz, VII-type transducer developed by the American NUWC in 1995 can reach 212dB at a water depth of 60m, but this type of transducer has a large mechanical quality factor and a narrow operating frequency band, and is not suitable for working in multiple frequency bands. Other transducers also have this common problem. Therefore, there is a need for a high-power underwater acoustic transducer that can take into account deep-sea work, high sound source level, and wide operating frequency band. Summary of the invention

[0006] In order to solve the above problems, the present invention discloses a multi-segment arc-coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer.

[0007] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A multi-segment circular arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer comprises a multi-arc radiation shell; the two ends of the multi-arc radiation shell along the length direction are arc shells, and the two end sides along the width direction are multi-segment circular arc shells; the multi-arc radiation shell is symmetrically arranged along the length direction and the width direction; the middle part of the multi-segment circular arc shell is a convex arc portion convex outward, and the two sides of the middle arc portion are concave arc portions tangent to the middle arc portion and concave inward; the upper cover of the multi-arc radiation shell is provided with an upper cover plate, and the lower cover is provided with a lower cover plate, and a driving module is installed inside the multi-arc radiation shell, and the driving module is a giant magnetostrictive rod; the multi-arc radiation shell applies prestress to the giant magnetostrictive rod, and the length direction of the giant magnetostrictive rod is parallel to the length direction of the middle axis of the multi-arc radiation shell and is symmetrically arranged relative to the length direction of the middle axis of the multi-arc radiation shell; the connection between the arc shell and the multi-segment circular arc shell is an arc transition section.

[0009] As a further improvement, there are two giant magnetostrictive rods, which are respectively located on both sides of the central axis of the multiple arc radiation shell in the length direction.

[0010] As a further improvement, the giant magnetostrictive rod is formed by coaxially bonding segmented rare earth giant magnetostrictive rods in sequence along the length direction.

[0011] As a further improvement, the upper cover plate and the lower cover plate are fixedly connected to the multi-arc radiation housing via fixing screws.

[0012] As a further improvement, cork rubber pads are provided between the upper cover plate, the lower cover plate and the multiple arc radiation housing.

[0013] As a further improvement, a watertight cable is installed on the upper cover plate.

[0014] A design method for a multi-arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer, wherein the multi-arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer is as described above; wherein the vertical distance from the top of the middle arc portion to the middle axis of the length direction of the multiple arc radiation shell is the height of the middle arc portion, which is h; the height difference between the height of the middle arc portion and the height of the arc transition section is Δh; and the length of the driving module of the multiple arc radiation shell is l;

[0015] Then: if the sound source level needs to be reduced and the bandwidth length needs to be increased, Δh should be increased, otherwise Δh should be reduced;

[0016] When Δh>0, if it is necessary to reduce the sound source level and increase the bandwidth length, then reduce the ratio of Δh / h, otherwise increase the ratio of Δh / h;

[0017] If the bandwidth length of the transducer is reduced and the sound source level is increased, the l / h ratio will be increased, otherwise the l / h ratio will be reduced.

[0018] As a further improvement, the curvature radii of the middle arc-shaped portion (521) and the two concave arc-shaped portions (522) are r2, r1, and r3 respectively;

[0019] When the transducer is subjected to greater and greater compression force as the water depth increases and the prestress of the drive module is increased, r1=r3>r2 is set;

[0020] When the transducer is subjected to increasing expansion force as the water depth increases and the prestress of the drive module decreases, set r1 = r3 <r2;

[0021] When the hydrostatic pressure on the transducer needs to be self-balanced through the shell as the water depth increases and the prestress of the drive module changes slowly, r1=r3=r2 is set.

[0022] Compared with the existing method, the present invention has the following advantages:

[0023] The present invention overcomes the disadvantages of the traditional type of flex-tension transducer that the prestress changes with the water depth, which reduces the output characteristics and electroacoustic efficiency of the transducer. The use of multiple arc-type shells can create more effective modes, thereby increasing the working bandwidth of the transducer; in addition, the arc of the concave-convex structure can reduce the sensitivity of the transducer surface stress to the change with the water depth, so that it can work in deeper sea areas. The present invention adopts the O-ring sealing method, which makes disassembly and assembly more convenient and has stronger reliability under dynamic vibration. The present invention is simple to make and has reliable process. The two ends also adopt the arc method. The transducer vibrates in all directions at the same time, maintaining a high sound source level in a longer frequency band. The present invention overcomes the problems of the traditional pressure compensation method, which is heavy, low reliability, and additional mass, thereby reducing the working performance of the transducer. The self-structured balance is adopted to greatly reduce the difficulty of research and development. The patented underwater acoustic transducer has the characteristics of deep-sea operation, wide bandwidth, high power, and light weight, and can be applied to active detection sonar, deep-sea water acoustic communication, deep-sea confrontation, marine environment monitoring, seabed geological and geomorphological detection and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The main view of the transducer structure of the present invention Figure 3 Dimensional cutaway isometric view.

[0025] Figure 2 It is a schematic diagram of the three-dimensional structure of the wavy shell of the transducer of the present invention.

[0026] Figure 3 It is an assembly diagram of the present invention in which prestress is applied to the driving module.

[0027] Figure 4 It is a curve diagram showing the change of prestress of the driving module with water depth according to the present invention.

[0028] Figure 5 The figure is a graph showing the changing trend of the prestress of the magnetostrictive rod in the transducer of the present invention as the water depth increases.

[0029] Specific implementation method

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0031] ① Such as Figure 1 As shown, the multi-section arc flextensional high-power giant magnetostrictive underwater acoustic transducer of the present invention mainly includes six fixing screws 1, an upper cover plate 2, a watertight cable 3, a cork rubber pad 4, a wavy radiation shell 5, a lower cover plate 6 and a driving module 7.

[0032] Among them, the wavy radiation shell of this embodiment is 200mm high, the thickness of the main arc section is 10mm, and it is made of 7075 hard aluminum alloy; the upper and lower cover plates are 10mm high each, and are also made of 7075 aluminum alloy; the O-ring diameter is 6mm, and it is made of nitrile rubber material; the cork rubber thickness is 6mm, and the screw length needs to be strictly controlled to be about 231.5mm, so that the compression ratio of the cork rubber and the O-ring is between 5% and 10% after tightening up and down.

[0033] The driving module of this embodiment is made of segmented rare earth giant magnetostrictive rods bonded together, using epoxy resin as an adhesive. There are two groups of rods, each with 5 rods. The total length of the two groups must be strictly controlled to be equal, with an error within 0.1mm. A single rod is cylindrical in shape, with a size of Φ20mm*50mm.

[0034] ② If Figure 2 As shown, the wavy radiation shell includes three main arcs, and the centers of the arcs on both sides are on the same side, and the center of the middle arc is on the other side. The curvature radii of the three arcs are r1, r2 and r3 respectively, the height of the middle arc is h, the height difference between the middle arc and the two ends is Δh, and the length of the driving part inside the shell is l.

[0035] In this embodiment, the arc height h, height difference Δh of the multiple arc-shaped housing, the length l of the driving part inside the housing, and the working bandwidth and sound source level of the transducer have the following relationship:

[0036] 1) When Δh < 0 (i.e., lower in the middle and higher at both ends), the bandwidth is narrow and the sound source level is high; when Δh = 0, the bandwidth and the sound source level are moderate; when Δh > 0, the bandwidth is long and the sound source level is low.

[0037] 2) When Δh > 0, the smaller the ratio of Δh / h, the longer the bandwidth of the transducer and the lower the sound source level. Conversely, the bandwidth is narrow and the sound source level is high.

[0038] 3) When the ratio of l / h is larger, the bandwidth of the transducer is narrower and the sound source level is higher; conversely, the bandwidth is long and the sound source level is low.

[0039] There is the following relationship between the curvature radii of the three arcs of the multi-circular-arc radiation housing in this embodiment and the hydrostatic pressure:

[0040] 1) When r1 = r3 > r2, as the water depth increases, the transducer is subjected to an increasingly large compressive force, and the prestress of the drive module increases.

[0041] 2) When r1 = r3 < r2, as the water depth increases, the transducer is subjected to an increasingly large expansion force, and the prestress of the drive module decreases.

[0042] 3) When r1 = r3 = r2, as the water depth increases, the hydrostatic pressure on the transducer is self-balanced through the housing and increases relatively slowly, and the prestress of the drive module increases slowly.

[0043] ③ The process of applying the prestress of the drive module in this embodiment is the key to ensuring the normal operation of this invention patent in deep sea. The specific process is as follows:

[0044] 1) Calculate the equivalent stiffness k of the drive module GMM and the equivalent stiffness k of the housing shell , and at the same time calculate the displacement change law T0 =

[0045] k GMM *x when the giant magnetostrictive drive module is under the action of prestress T0, and obtain that when T0 = 25 MPa, the compression displacement x = x1 of the drive module.

[0046] 2) Then use the finite element simulation model to calculate the compression displacement x2 of the multi-circular-arc radiation housing in the direction of the giant magnetostrictive drive module when the target water depth is h water .

[0047] 3) Calculate the relationship between T0 and the displacement of the housing in the T0 direction, and obtain T0 = k shell *x. After pulling the housing apart by a certain distance x3 in the air and putting in the drive unit, under the action of the restoring force T shell = k shell *x3 of the housing, the drive unit is compressed by x4, and there is k shell *(x3 - x4)＝ k GMM *x4;

[0048] 4) After assembly in air, place the transducer in water for 1 h. water Depth, and according to the above scheme, step 3) needs to pull the transducer housing apart in the air, and the pulling apart process is the key to applying prestress to the drive module, and its assembly process is as follows Figure 3 As shown, the specific implementation is:

[0049] The two ends of the multi-section arc-shaped radiation shell are respectively connected and fixed to a 20mm stainless steel plate by screws. Two 10-ton hydraulic jacks are placed on the stainless steel plate at one end. The steel plate at the other end is pushed open by the jack to drive the shell to be pulled open. After the drive module is placed in, the pressure is released to achieve a rigid connection between the shell and the drive module and complete the prestressing.

[0050] ④ Therefore, the following examples illustrate the characteristics of the present invention: the middle arc height of the wavy radiation shell is set to h = 100mm, the height difference between the two ends is Δh = 60mm, the length of the driving part inside the shell is l = 200mm, the curvature radius r1, r2, and r3 of the three arcs are all 80mm, the total length is 400mm, and the shell height is 200mm. The sound source level curve is calculated by simulation software as follows: Figure 4 As shown, it can be seen that at this time, the transducer has four obvious maximum sound source level points, the frequency range covers 900 ~ 3500Hz, and the sound source level of each resonance point is greater than 200dB, and the maximum sound source level exceeds 205dB, achieving high-power sound wave emission in multiple frequency bands.

[0051] In addition, in terms of deepwater working performance, such as Figure 5 The figure shows the trend of the prestress of the magnetostrictive rod in the transducer of the present invention as the water depth increases. The curve shows that under different initial prestresses, the prestress changes slowly with the water depth. The present invention adopts an initial prestress of 20MPa, which changes to 25MPa after a water depth of 60 to 80m, and increases slowly, and can work at all depths including the deep sea. It is only necessary to consider the tolerance of the thickness to the hydrostatic pressure, ensuring that it does not exceed the yield strength of duralumin 400MPa.

[0052] The above is only a specific guiding implementation mode of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A multi-segment arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer, characterized in that: The invention comprises a multiple arc radiation shell (5); the two ends of the multiple arc radiation shell (5) along the length direction are arc shells (51), and the two end sides along the width direction are multiple arc shells (52); the multiple arc radiation shell (5) is symmetrically arranged along the length direction center axis and the width direction center axis; the middle part of the multiple arc shell (52) is a convex arc portion (521) convex outward, and the two sides of the middle arc portion (521) are concave arc portions (522) tangent to the middle arc portion (521) and concave inward; the upper cover of the multiple arc radiation shell (5) is provided with an upper cover plate (2), and the lower cover is provided with a lower cover plate (6); a driving module (7) is installed inside the multiple arc radiation shell (5), and the driving module (7) is a giant magnetostrictive rod; The multiple arc radiation shell (5) applies prestress to the giant magnetostrictive rod, the length direction of the giant magnetostrictive rod is parallel to the central axis of the multiple arc radiation shell (5) in the length direction and is symmetrically arranged relative to the central axis of the multiple arc radiation shell (5) in the length direction; the connection between the arc shell (51) and the multiple arc shells (52) is an arc transition section (53).

2. The multi-segment arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer according to claim 1, characterized in that: There are two giant magnetostrictive rods, which are respectively located on both sides of the central axis of the multiple arc-shaped radiation housing (5) in the length direction.

3. The multi-segment arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer according to claim 1, characterized in that: The giant magnetostrictive rod is formed by coaxially bonding segmented rare earth giant magnetostrictive rods in sequence along the length direction.

4. The multi-segment arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer according to claim 1, characterized in that: The upper cover plate (2) and the lower cover plate (6) are fixedly connected to the multiple arc-shaped radiation housing (5) via fixing screws (1).

5. The multi-segment arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer according to claim 1, characterized in that: Cork rubber pads (4) are provided between the upper cover plate (2), the lower cover plate (6) and the multiple arc-shaped radiation housing (5).

6. The multi-segment arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer according to claim 1, characterized in that: A watertight cable (3) is installed on the upper cover plate (2).

7. A design method for a multi-segment arc-coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer, characterized in that: The multi-arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer is as described in any one of claims 1 to 6; wherein the vertical distance from the top of the middle arc portion (521) to the central axis of the length direction of the multiple arc radiation shell (5) is the height of the middle arc portion (521) is h, the height difference between the height of the middle arc portion (521) and the height of the arc transition section (53) is Δh, and the length of the driving module (7) of the multiple arc radiation shell (5) is l; Then: if the sound source level needs to be reduced and the bandwidth length needs to be increased, Δh should be increased, otherwise Δh should be reduced; When Δh>0, if it is necessary to reduce the sound source level and increase the bandwidth length, then reduce the ratio of Δh / h, otherwise increase the ratio of Δh / h; If the bandwidth length of the transducer is reduced and the sound source level is increased, the l / h ratio will be increased, otherwise the l / h ratio will be reduced.

8. The design method of a multi-arc coupled high-power deep-sea giant magnetostrictive underwater acoustic transducer according to claim 7, characterized in that: The curvature radii of the middle arc-shaped portion (521) and the two concave arc-shaped portions (522) are r2, r1, and r3 respectively; When the transducer is subjected to greater and greater compression force as the water depth increases and the prestress of the drive module is increased, r1=r3>r2 is set; When the transducer is subjected to increasing expansion force as the water depth increases and the prestress of the drive module decreases, set r1 = r3 <r2; When the hydrostatic pressure on the transducer needs to be self-balanced through the shell as the water depth increases and the prestress of the drive module changes slowly, r1=r3=r2 is set.

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