Highly sensitive sound system

Abstract

An acoustic system and a method of fabricating an acoustic system, the acoustic system including at least one tube having at least one opening through which acoustic waves pass to increase the sensitivity of the acoustic system, and at least one hydrophone within the at least one tube, the at least one hydrophone being encapsulated, the method including inserting the at least one encapsulated hydrophone into the at least one tube having at least one opening through which acoustic waves pass to increase the sensitivity of the at least one hydrophone, inserting the at least one tube into a fluid, and receiving acoustic waves through the fluid with the at least one hydrophone.

Description

[Technical Field]

[0001] (Reference to Related Application) This application claims the benefit of U.S. Provisional Application No. 63 / 383,539, filed November 14, 2022, which is incorporated herein by reference. [Background technology]

[0002] In undersea sensing or acoustic navigation and ranging (SONAR) applications, it is often advantageous to deploy volumetric arrays of various shapes. These array design methods require sensors to be held at specific, precise positions relative to each other to form a volumetric array within the water column.

[0003] Fixing or positioning sensing elements using mechanical structures is often difficult. Installing sensitive transducers within large and / or rigid structures often results in unwanted mechanical noise or destructive acoustic interference to the propagating sound waves of interest when supporting structure resonant modes are excited. Additionally, subsea systems are size, weight, and power (SWAP) constrained, creating a challenging design space.

[0004] In many cases, acoustic designers must accept and design around reduced sensor sensitivity or interfering structures to accommodate the structures required to create an underwater volumetric array. Summary of the Invention

[0005] In accordance with the concepts described herein, exemplary acoustic systems and methods allow for anchoring underwater acoustic sensors that achieve passive increase in sensitivity instead of reduction or some known inference.

[0006] In accordance with the concepts described herein, exemplary acoustic systems are constructed using composite materials that are durable and have high specific stiffness, and that do not risk corrosion during long-term subsea deployments.

[0007] In accordance with the concepts described herein, exemplary acoustic systems and methods provide an increase in passive sensor sensitivity of approximately 3 dB, depending on the system configuration.

[0008] The methods and processes for making and using the disclosed embodiments may be understood by reference to the accompanying drawing figures. It should be understood that the components and structures shown in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the concepts described herein. Like reference characters designate corresponding parts throughout the different views. Moreover, embodiments are illustrated in the drawings by way of example, and not by way of limitation. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1 is a diagram of an exemplary sound system of the present disclosure. [Figure 1B] FIG. 1 is a diagram of an exemplary sound system of the present disclosure. [Figure 2] FIG. 2 is a diagram of the exemplary encapsulated hydrophone of FIG. 1. [Figure 3A] FIG. 1 illustrates an exemplary tapered conformal mesh tube of the present disclosure. [Figure 3B] 1 is a photograph of an exemplary conformal mesh tube with an enclosed hydrophone inserted therein. [Figure 4] 1A-1C are diagrams of exemplary shapes of the end of a tube of the present disclosure. [Figure 5] 1 is an exemplary method of increasing the sensitivity of an acoustic system of the present disclosure. [Figure 6] 1 is a graphical representation of an exemplary sensor response according to an exemplary embodiment of the present disclosure. [Figure 7] A shows the first duct mode, and B shows the second duct mode for an exemplary wavelength. [Figure 8] 1 illustrates a first-order analytical model of an exemplary sensor. [Figure 9] 10 shows sample results for an exemplary sensor. DETAILED DESCRIPTION OF THE INVENTION

[0010] Deploying volumetric arrays is challenging from a mechanical standpoint. The present disclosure provides systems and methods that keep the array geometry and sensor positions known relative to each other for all cross-flow conditions. The present disclosure also provides exemplary systems and methods for holding sensors in known positions relative to each other without causing structurally destructive interference. The present disclosure also provides a system that is lightweight, rigid, and durable, will not corrode during long-term deployment at sea, and can be tuned to achieve amplification only in the bands of interest.

[0011] 1A and 1B illustrate an exemplary acoustic system 100 with enhanced sensitivity. Fig. 1A shows the acoustic system 100 in an exemplary stowed configuration, and Fig. 1B shows the acoustic system in an exemplary deployed configuration. In the exemplary embodiment, the acoustic system 100 includes at least one tube 101 that houses at least one hydrophone 103, the at least one tube 101 having at least one opening to allow acoustic waves to be received by the at least one hydrophone 103.

[0012] 1A and 1B show four 6-foot long collapsible tubes 101 housing hydrophones 103 in the X and Y axes in a stowed ( FIG. 1A ) and deployed ( FIG. 1B ) state, with one tube 101 without a hydrophone 103 used to position the four collapsible tubes along the Z axis. However, this disclosure is not intended to be so limited. In alternative embodiments, the acoustic system 100 may include one tube 101 housing at least one hydrophone 103 in only the X axis, only the Y axis, and only the Z axis; four tubes 101 housing at least one hydrophone 103 in each of any two axes (e.g., the X and Y axes, the X and Z axes, and the Y and Z axes); and five tubes 101 housing at least one hydrophone 103 in all three axes (e.g., the X axis, the Y axis, and the Z axis). The tube 101 may be short enough (e.g., 1 inch or more) to accommodate a minimum of one hydrophone 103, or may be long enough (e.g., 1 foot or more) to accommodate any user-definable number of hydrophones 103.

[0013] The tube 101 housing the hydrophone 103 includes at least one opening in the tube 101 to allow acoustic waves to be received by the hydrophone 103. The at least one opening may be along the length of the tube 101, at one end of the tube 101, at both ends of the tube 101, aligned with the hydrophone 103, not aligned with the hydrophone 103, or any combination thereof. In an exemplary embodiment, the opening in the tube 101 allows a fluid, such as seawater, to flow freely through the tube 101 and around the hydrophone 103.

[0014] The tube 101 is constructed from a material (e.g., composite, metal, plastic) that may be strong, rigid, and corrosion-resistant. Composite materials include fiberglass, carbon fiber, and epoxy. Exemplary metals include brass, bronze, stainless steel, titanium, aluminum, nickel, gold, etc. In an exemplary embodiment, the acoustic system is configured for immersion in fluids including Newtonian fluids (e.g., seawater, freshwater, etc.). In other embodiments, the acoustic system is configured for immersion in non-Newtonian fluids (e.g., paint, starch suspensions, etc.).

[0015] The tube 101 increases the sensitivity of the hydrophone 103 compared to the hydrophone 103 alone in the fluid. A resonant frequency is excited in the tube 101 by an acoustic wave (e.g., a sound wave) impinging on the tube 101. Coupling the tube 101 to the hydrophone 103 through the fluid allows for passive amplification of pressure waves caused by the acoustic wave on the active surface of the hydrophone 103. The sensitivity of the hydrophone 103 may depend on the position of the hydrophone 103 within the tube 101.

[0016] The geometry of the tube 101 and hydrophone 103 can affect the sensitivity of the hydrophone 103. The clearance between the outer surface of the hydrophone 103, including the encapsulation material of the hydrophone 103, described in more detail below with reference to FIG. 2, and the inner surface of the tube 101, as measured by the ratio of the inner diameter of the tube 101 divided by the outer diameter of the hydrophone 103, can be anywhere from small (e.g., 1.1) to large (e.g., greater than 100).

[0017] There is a correlation between the size of the hydrophone 103 and the frequency at which the hydrophone 103 is most sensitive. The smaller the hydrophone 103, the more sensitive it is at high frequencies. The increased fluid movement caused by acoustic waves between the hydrophone 103 and the tube 101 increases the sensitivity of the hydrophone 103. The length of the tube 101 affects the sensitivity of the hydrophone 103 (e.g., the longer the tube 101, the more sensitive the hydrophone 103).

[0018] 2 is a diagram of the exemplary encapsulated hydrophone 103 of FIG. 1. In one exemplary embodiment, the hydrophone 103 is a passive hydrophone 103 (e.g., does not require a power source) and includes two electrodes. In one exemplary embodiment, the hydrophone 103 is a piezoelectric device. In one embodiment in which multiple hydrophones 103 are included in the tube 101, the hydrophones 103 may be connected in series or parallel. Furthermore, each hydrophone 103 is encapsulated in a material 201 (e.g., polyurethane) that is impermeable to the fluid in which the hydrophone 103 is placed.

[0019] FIG. 3A is a diagram of an exemplary tapered conformal mesh tube 301 of the present disclosure. In an alternative embodiment, the tube 101 of FIG. 1 may include the tapered tube 301 of FIG. 3A, where the tube 301 has a lattice structure, the lattice providing rigidity and strength while including multiple openings in the tube 301. The lattice structure of the tube 301 is commonly referred to as a conformal mesh (isomesh) or conformal grid (isogrid). The tapered isomesh tube 301 may be constructed from the same materials identified above with respect to the tube 101 of FIG. 1. In an alternative embodiment, the tapered lattice tube 301 may not be tapered.

[0020] FIG. 3B is a photograph of an exemplary conformal mesh tube 301 with an enclosed hydrophone 103 inserted therein. In the illustrated embodiment, the mesh includes a series of helical windings with a lattice configuration that wraps around the hydrophone. In some embodiments, the winding spacing is constant. In other embodiments, the winding spacing varies over the length and may vary in shape (e.g., the openings formed by the windings may be circular, square, polygonal, etc., as shown in FIG. 4, described below). The open areas of the tube 301 allow acoustic waves to enter the tube 301 and apply pressure to the hydrophone 103. Without the openings in the tube, the pressure spectrum observed by the hydrophone within the tube would change significantly compared to the pressure spectrum of a tube with openings, rendering signal processing useless.

[0021] 4 is a diagram of exemplary shapes of both the ends of the tubes 101 / 301 and the openings along the length of the tubes 101 / 301 of the present disclosure. In one exemplary embodiment, the shapes of the ends of the tubes 101 / 301 and the openings along the length of the tubes 101 / 301 may be circular 401, square 403, or polygonal 405.

[0022] 5 is an exemplary method 500 of an enhanced sensitivity acoustic system of the present disclosure. The exemplary method 500 includes encapsulating at least one hydrophone in step 501. In one exemplary embodiment, the at least one hydrophone may be a piezoelectric device, and the encapsulant (e.g., polyurethane) may be impermeable to Newtonian fluids (e.g., seawater, freshwater, etc.) and non-Newtonian fluids.

[0023] Step 503 of method 500 includes inserting at least one encapsulated hydrophone into at least one tube having at least one opening through which acoustic waves pass to increase the sensitivity of the at least one hydrophone. In one embodiment, the tube may be made from a composite material, metal, or plastic, as described above. Furthermore, the tube may be tapered or not, may include an isomesh, and may have an end shape that is round, square, or polygonal. In one exemplary embodiment, a space exists between the outer surface of each encapsulated hydrophone and the inner surface of the tube into which the hydrophone is inserted, and the space may be as described above.

[0024] Step 505 includes inserting at least one tube into the fluid. In one exemplary embodiment, each tube inserted into the fluid may be oriented along one of three axes (e.g., the X-axis, the Y-axis, or the Z-axis) to a user-definable depth. Furthermore, the fluid may be a Newtonian or a non-Newtonian fluid, as described above.

[0025] Step 507 includes receiving acoustic waves through the fluid with at least one hydrophone.

[0026] 6 is a graphical representation of an exemplary sensor response versus the free-field response of an exemplary sensor within a 2-foot long isotruss. As can be seen, the response has a frequency maximum at 1000 Hz and a frequency minimum at 2500 Hz.

[0027] Figure 7A shows the first duct mode at 1000 Hz, and Figure 7B shows the second duct mode at 2500 Hz. Assuming the isotruss does not significantly change the speed of sound in the water inside the truss, the wavelengths at 1000 Hz and 2500 Hz are λ = c / f = 5 ft at 1000 Hz and 2 ft at 2500 Hz. The modal responses are shown with corresponding wavelengths that fall approximately inside the truss. For the first duct mode, the pressure associated with the acoustic mode is in phase with the incident wave pressure, thereby increasing the net pressure at the sensor (maximum RVS at 1000 Hz). For the second duct mode, the pressure associated with the acoustic mode is out of phase with the incident wave pressure, thereby significantly decreasing the net pressure at the sensor (minimum RVS at 2500 Hz).

[0028] Figure 8 shows a first-order analytical model of an exemplary sensor. The pressure at the sensor location (0) includes direct pressure from the incident wave because the isotruss contains many open areas, as well as secondary pressure from highly damped acoustic modes inside the isotruss. The pressure normalized to the incident pressure can be approximated by:

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[0029] Figure 9 shows the rad Sample results for an example sensor are shown using =0.2, 0.4, 0.6. As can be seen, there is a peak around 1000 Hz and a minimum around 2400 Hz.

[0030] Although illustrative embodiments of the present disclosure have been described, it will be apparent to those skilled in the art that other embodiments incorporating these concepts may also be used. The embodiments contained herein should not be limited to the disclosed embodiments, but rather should be limited only by the spirit and scope of the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

[0031] Elements of different embodiments described herein can be combined to form other embodiments not specifically described above. Various elements described in the context of a single embodiment may be provided separately or in any suitable subcombination. Other embodiments not specifically described herein are also within the scope of the following claims.

[0032] Various embodiments of the concepts, systems, devices, structures, and techniques for which protection is sought are described herein with reference to the associated drawings. As noted above, in embodiments, the concepts and features described herein may be embodied in a digital multi-beam beamforming system. Alternative embodiments may be contemplated without departing from the scope of the concepts, systems, devices, structures, and techniques described herein.

[0033] It should be noted that in the above description and drawings, various connections and relationships (e.g., above, below, adjacent, etc.) are described between elements. These connections and / or relationships may be direct or indirect unless otherwise specified, and the described concepts, systems, devices, structures, and techniques are not intended to be limiting in this regard. Thus, coupling of entities can refer to direct or indirect coupling, and relationship between entities may be direct or indirect relationship.

[0034] As an example of an indirect positional relationship, reference in this description to forming layer "A" above layer "B" includes the situation where one or more intermediate layers (e.g., layer "C") are between layer "A" and layer "B," so long as the relevant properties and functions of layer "A" and layer "B" are not substantially altered by the intermediate layer(s). The following definitions and abbreviations should be used for interpreting the claims and the specification. As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contains," or "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, mixture, process, method, article, or device that includes a list of elements is not necessarily limited to only those elements and may include other elements not expressly listed or other elements inherent to such composition, mixture, process, method, article, or device.

[0035] Additionally, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "one or more" and "one or more" are understood to include any integer number greater than or equal to one, i.e., 1, 2, 3, 4, etc. The term "plurality" is understood to include any integer number greater than or equal to two, i.e., 2, 3, 4, 5, etc. The term "connected" can include indirect and direct "connections."

[0036] References in the specification to "one embodiment," "an embodiment," "an exemplary embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but that all embodiments may include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with one embodiment, it is believed to be within the knowledge of one of ordinary skill in the art to affect such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly stated.

[0037] For purposes of this description, the terms "above," "below," "right," "left," "vertical," "horizontal," "top," "bottom" (to name a few) and their derivatives refer to the structures and methods described, as well as the orientation of the drawings. The terms "overlying," "atop," "ontop," "positioned on," or "positioned atop" mean that a first element, such as a first structure, is above a second element, such as a second structure, and intervening elements, such as interfacial structures, may be present between the first and second elements. The term "direct contact" means that a first element, such as a first structure, and a second element, such as a second structure, are connected without intervening elements. Such terms may also be referred to as directional or positional terms.

[0038] The use of ordinal numbers such as "first," "second," "third," etc. in the claims to modify claim elements does not, in itself, imply a priority, precedence, or ordering of one claim element relative to other claim elements, or a chronological order in which method actions are performed, but is merely used as a label to distinguish one claim element with a particular name from another element with the same name (other than the use of the ordinal number) to distinguish between claim elements.

[0039] The terms "approximately" and "about" may be used in some embodiments to mean within ±20% of a target value, in some embodiments within ±10% of a target value, in some embodiments within ±5% of a target value, and even in some embodiments within ±2% of a target value. The terms "approximately" and "about" may include the target value. The term "substantially equal" may be used to refer to values ​​that are in some embodiments within ±20% of each other, in some embodiments within ±10% of each other, in some embodiments within ±5% of each other, and even in some embodiments within ±2% of each other.

[0040] The term "substantially" may be used in some embodiments to refer to values ​​within ±20%, in some embodiments within ±10%, in some embodiments within ±5%, and even in some embodiments within ±2% of a comparison measurement. For example, a first direction that is "substantially" perpendicular to a second direction may in some embodiments refer to a first direction that is within ±20% of a 90° angle with the second direction, in some embodiments within ±10% of a 90° angle with the second direction, in some embodiments within ±5% of a 90° angle with the second direction, and even in some embodiments within ±2% of a 90° angle with the second direction.

[0041] It is to be understood that the disclosed subject matter is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings, as the disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways.

[0042] It is also to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. Thus, those skilled in the art will appreciate that the conception underlying the present disclosure may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out some of the purposes of the disclosed subject matter. Accordingly, the claims should be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter.

[0043] While the disclosed subject matter has been described and illustrated in the foregoing exemplary embodiments, it should be understood that the disclosure is made by way of example only and that numerous changes may be made in the details of the implementation of the disclosed subject matter without departing from the spirit and scope of the disclosed subject matter.

Claims

1. 1. An audio system comprising: at least one tube having at least one opening through which acoustic waves pass to increase the sensitivity of the acoustic system; at least one encapsulated hydrophone within the at least one tube; Sound system.

2. The acoustic system of claim 1 , wherein the acoustic system is configured for immersion in a fluid.

3. 2. The acoustic system of claim 1, wherein the at least one opening in the at least one tube comprises at least one opening along a length of the at least one tube at one end of the at least one tube that is aligned with the at least one encapsulated hydrophone and / or that is not aligned with the at least one encapsulated hydrophone.

4. The acoustic system of claim 1 , wherein the at least one tube comprises a conformal mesh.

5. The acoustic system of claim 1 , wherein the at least one tube comprises at least one tapered tube.

6. 10. The acoustic system of claim 1, wherein the at least one tube comprises at least one tube having an end shape comprising a circle, a square, and / or a polygon, and the at least one opening comprises at least one opening having an opening shape comprising a circle, a square, and / or a polygon.

7. The acoustic system of claim 1 , wherein the at least one tube comprises a composite material, a metal, and / or a plastic.

8. The acoustic system of claim 1 , wherein the encapsulation of the at least one encapsulated hydrophone comprises polyurethane.

9. The acoustic system of claim 1 , wherein the at least one encapsulated hydrophone comprises at least one piezoelectric device.

10. 1. A method of making an acoustic system, comprising: inserting at least one encapsulated hydrophone into at least one tube having at least one opening through which acoustic waves pass to increase the sensitivity of the at least one encapsulated hydrophone; inserting the at least one tube into a fluid; receiving the acoustic waves through the fluid with the at least one encapsulated hydrophone. method.

11. The method of claim 10 , wherein the at least one tube is oriented in an X-axis, a Y-axis, a Z-axis, and / or any combination thereof.

12. The method of claim 11 , further comprising immersing the acoustic system in a fluid.

13. 11. The method of claim 10, wherein the at least one opening in the at least one tube comprises at least one opening along the length of the at least one tube at one end of the at least one tube that is aligned with the at least one encapsulated hydrophone and / or that is not aligned with the at least one encapsulated hydrophone.

14. The method of claim 10 , wherein the at least one tube comprises a conformal mesh.

15. The method of claim 10 , wherein the at least one tube comprises at least one tapered tube.

16. 11. The method of claim 10, wherein the at least one tube comprises at least one tube having an end shape comprising a circle, a square, and / or a polygon, and the at least one opening comprises at least one opening having an opening shape comprising a circle, a square, and / or a polygon.

17. The method of claim 10 , wherein the at least one tube comprises a composite material, a metal, and / or a plastic.

18. The method of claim 10 , wherein the encapsulation of the at least one encapsulated hydrophone comprises polyurethane.

19. The method of claim 10 , wherein the at least one encapsulated hydrophone comprises at least one piezoelectric device.

20. 1. An audio system comprising: at least one tube having at least one opening through which acoustic waves pass to increase the sensitivity of the acoustic system; at least one encapsulated hydrophone within said at least one tube; means for holding the hydrophone without structurally disruptive interference; Sound system.

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