Systems and methods for compensating for compressibility and thermal expansion coefficient mismatch in buoyancy controlled underwater vehicles

• US 8,381,672 B1
• Filed: 06/02/2010
• Issued: 02/26/2013
• Est. Priority Date: 06/02/2009
• Status: Active Grant

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Eriksen, Charles C.
• Primary Examiner(s): Olson, Lars A
• Application Number:
  US12/792,620
• Time in Patent Office: 1,000 Days
• Field of Search: 114/315, 114/333, 114/338, 114/124, 114/125, 114/331, 623/8, 441/6, 441/7, 441/11, 441/21, 441/28, 441/29
• US Class Current: 114/333
• CPC Class Codes: B63G 8/22 Adjustment of buoyancy by water ballasting; Emptying equipment for ballast tanks conduits for emptying or ballasting on vessels in general B63B13/00; stabilising vessels using ballast tanks B63B43/06

Abstract

Systems and methods for compensating for compressibility and thermal expansion coefficient mismatch in buoyancy controlled or buoyancy-driven underwater vehicles are disclosed herein. An underwater vehicle configured in accordance with one embodiment of the disclosure, for example, can include a hull and a compartment carried by the hull and at least partially flooded with a first liquid having similar properties as a surrounding liquid into which the hull is configured to be deployed. The first liquid has a first compressibility and thermal expansion coefficient. The underwater vehicle can further include a compressibility and thermal expansion coefficient compensation system comprising a container filled or at least partially filled with a compressible liquid comprising silicone in the compartment. The compressible liquid has a second compressibility higher than the first compressibility and second thermal expansion coefficient higher than the first thermal expansion coefficient. The compressible liquid can include, for example, hexamethyldisiloxane (HMDS).

Claims

1. An underwater vehicle, comprising:

a hull;

a compartment carried by the hull and at least partially flooded with a first liquid having similar properties as a surrounding liquid into which the hull is configured to be deployed, wherein the first liquid has a first compressibility; and

a compressibility compensation system comprising a container in the compartment and at least partially filled with a compressible liquid comprising silicone, the compressible liquid having a second compressibility higher than the first compressibility.

2. The underwater vehicle of claim 1 wherein the compressible liquid comprises a polydimethylsiloxane (PDMS) silicone liquid.

3. The underwater vehicle of claim 1 wherein the compressible liquid comprises hexamethyldisiloxane (HMDS).

4. The underwater vehicle of claim 1 wherein the second compressiblity is at least double times greater than the first compressiblity.

5. The underwater vehicle of claim 1 wherein the first liquid has a first thermal expansion coefficient and the compressible liquid comprises a silicone fluid having a second thermal expansion coefficient higher than the first thermal expansion coefficient.

6. The underwater vehicle of claim 1 wherein the container comprises a flexible, pliable material having an arbitrary shape.

7. The underwater vehicle of claim 1 wherein the hull is a pressure hull and the surrounding liquid into which the pressure hull is to be deployed is seawater, and wherein:

the pressure hull a volume V, compressibility K_V, and thermal expansion coefficient α

_V;

the compressible liquid has a volume V_C, compressibility K_C and thermal expansion coefficient α

_C;

the seawater has a compressibility of K_S and thermal expansion coefficient α

_S and wherein V_C is approximately equivalent to

8. The underwater vehicle of claim 1 wherein the compartment is a first compartment and the container is a first container, and wherein the underwater vehicle further comprises:

a second compartment carried by the hull and at least partially flooded by the first fluid; and

a second container in the second compartment and at least partially filled with the compressible liquid.

9. The underwater vehicle of claim 1 wherein the hull comprises a pressurized portion having a first volume, and wherein the compressibility compensation system has a second volume a fraction less than one of the first volume.

10. The underwater vehicle of claim 1 wherein the compartment have a generally hydrodynamic shape, and wherein the underwater vehicle further comprises:

a wing fin coupled to the hull;

a rudder fin coupled to the compartment, wherein the rudder fin is oriented generally normal to the wing fin; and

an antenna coupled to the underwater vehicle and configured to exchange signals with a remote device.

11. The underwater vehicle of claim 1, further comprising:

a buoyancy control system comprising an internal reservoir within the hull, an external hydraulic accumulator within the compartment, and a pump configured to change the buoyancy of the underwater vehicle by moving a liquid between the internal reservoir and the external hydraulic accumulator.

12. An underwater vehicle having a controllable buoyancy volume V, the underwater vehicle comprising a compressee having (a) a bladder, and (b) a compressible fluid within the bladder, wherein the compressee has a total volume V_C less than V, and V_C comprises approximately

13. The underwater vehicle of claim 12 wherein the compressible fluid comprises a silicone-based fluid having a compressiblity at least double that of seawater.

14. A buoyancy controlled underwater vessel, comprising:

a body having a compressibility less than a liquid medium into which the vessel is to be deployed, the body including a first portion configured to be pressurized and a second portion separated from the first portion, wherein the second portion is configured to be flooded with the liquid medium;

a flexible, pliable container positioned within the second portion of the body; and

a volume of silicone material at least partially filling the pliable container.

15. The underwater vessel of claim 14 wherein the silicone material comprises a polydimethylsiloxane (PDMS) silicone liquid.

16. The underwater vessel of claim 14 wherein the silicone material comprises hexamethyldisiloxane (HMDS).

17. The underwater vessel of claim 14 wherein the silicone material has a higher thermal expansion than water.