Method and device for low-noise underwater propulsion and for reducing hull drag

• US 20040121664A1
• Filed: 07/31/2003
• Published: 06/24/2004
• Est. Priority Date: 12/18/2002
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Hassan, Ahmed A., Domzalski, David B.
• Granted Patent: US 6,860,770 B2
• Time in Patent Office: Days
• US Class Current: 440/38
• CPC Class Codes: B63G 2013/022 using means for reducing noise emission into air or water
• CPC Class Codes: B63H 11/06 of reciprocating type
• CPC Class Codes: F04B 17/044 using solenoids directly actuating the piston

Abstract

A method and apparatus is disclosed for producing propulsion underwater with minimal acoustical emission. In basic concept, the method comprises the expulsion and sucking of liquid into and out of a liquid port of a watercraft in a manner generating compression and expansion waves adjacent the liquid port. Such expansion and compression waves generate a positive net thrust on the watercraft in a direction opposite that of their expulsion. Also disclosed is a method and apparatus for reducing the drag caused by hull skin friction by actively increasing the momentum of the liquid stream boundary layer adjacent a watercraft via the expulsion of fluid (liquid or gas) from ports in the hull of such a watercraft.

Claims

1. A method comprising:

providing a watercraft, the watercraft comprising a hull, a fluid chamber, and at least one fluid port, the fluid port allowing fluid communication between the fluid chamber and a liquid environment external to the watercraft;

propelling the watercraft within the liquid environment in a manner such that a liquid stream boundary layer exist adjacent the hull of the watercraft; and

repetitively increasing and decreasing the internal volume of the fluid chamber in a manner such that fluid is expelled from the fluid port into the liquid stream boundary layer.

2. A method in accordance with claim 1 wherein the step of repetitively increasing and decreasing the internal volume of the fluid chamber occurs in a manner such that the fluid expelled from the fluid port into the liquid stream boundary layer is in a gaseous state as it is expelled.

3. A method in accordance with claim 2 wherein the step of repetitively increasing and decreasing the internal volume of the fluid chamber occurs in a manner such that the decreasing of the internal volume of the fluid chamber causes the expulsion of fluid from the fluid port into the liquid stream boundary layer and such that the increasing of the internal volume of the fluid chamber causes fluid in a gaseous state to be drawn into the fluid chamber from a gaseous environment external to the watercraft.

4. A method in accordance with claim 3 wherein the fluid port constitutes a first fluid port and wherein the step of providing the watercraft occurs in a manner such that the watercraft comprises a second fluid port and first and second valves, the second fluid port allowing communication of fluid between the fluid chamber and the gaseous environment external to the watercraft, each of the first and second valves being movable between opened and closed positions, the first valve being configured and adapted to prevent fluid communication between the first fluid port and the fluid chamber when in its closed position and to allow such communication when in its opened position, the second valve being configured and adapted to prevent fluid communication between the second fluid port and the fluid chamber when in its closed position and to allow such communication when in its opened position, the step of repetitively increasing and decreasing the internal volume of the fluid chamber occurring in a manner such that the decreasing of the internal volume of the fluid chamber occurs with the first valve in its opened position and the second the internal volume of the fluid chamber occurs with the first valve in its closed position and the second valve in its opened position.

5. A method in accordance with claim 1 wherein the step of repetitively increasing and decreasing the internal volume of the fluid chamber occurs in a manner such that fluid expelled from the fluid port into the liquid stream boundary layer is in a liquid state as it is expelled.

6. A method in accordance with claim 5 wherein the step of repetitively increasing and decreasing the internal volume of the fluid chamber occurs in a manner such that fluid in a liquid state is drawn into the fluid port from the liquid stream boundary layer.

7. A method in accordance with claim 6 wherein the fluid port constitutes a first fluid port and wherein the step of providing the watercraft occurs in a manner such that the watercraft comprises a second fluid port, the second fluid port allowing fluid communication between the fluid chamber and the liquid environment, and wherein the step of repetitively increasing and decreasing the internal volume of the fluid chamber occurs in a manner such that fluid in a liquid state is intermittently expelled from the second fluid port into the liquid environment and such that fluid in a liquid state is intermittently drawn into the second fluid port, the step of propelling the watercraft within the liquid environment occurring via the expulsion of liquid from the second liquid port.

8. A method in accordance with claim 5 wherein the step of repetitively increasing and decreasing the internal volume of the fluid chamber occurs in a manner such that the repetitiveness occurs with a frequency below one-hundred Hertz.

9. A method in accordance with claim 1 wherein the step of providing the watercraft further comprises providing the watercraft such that the watercraft has an electromagnetic actuator, the step of repetitively increasing and decreasing the internal volume of the fluid chamber further comprising using the electromagnetic actuator to repetitively increase and decrease the internal volume of the fluid chamber.

10. A method comprising:

providing a watercraft, the watercraft comprising a hull and a reciprocating member;

providing a liquid environment external to the watercraft, the liquid environment being in liquid communication with the reciprocating member of the watercraft;

propelling the watercraft within the liquid environment in a manner such that a liquid stream boundary layer exist adjacent the hull of the watercraft; and

increasing momentum within the liquid stream boundary layer by moving the reciprocating member in a linearly reciprocating manner relative to the hull of the watercraft.

11. A method in accordance with claim 10 wherein the step of providing the watercraft further comprises providing the watercraft such that the watercraft has an electromagnetic actuator, and wherein the step of increasing momentum within the liquid stream boundary layer comprises using the electromagnetic actuator to drive the movement of the reciprocating member.

12. A method in accordance with claim 10 wherein the step of increasing momentum within the liquid stream boundary layer occurs via alternating compression and expansion waves created by the moving of the reciprocating member in the linearly reciprocating manner relative to the hull of the watercraft.

13. A method in accordance with claim 12 wherein the step of increasing momentum within the liquid stream boundary layer via alternating compression and expansion waves occurs in a manner such that the alternating compression and expansion waves have a frequency below one-hundred hertz.

14. A method in accordance with claim 10 wherein the watercraft comprises a liquid port, the liquid environment being in liquid communication with the reciprocating member via the liquid port, and wherein the step increasing momentum within the liquid stream boundary layer occurs in a manner such that the moving of the reciprocating member in the linearly reciprocating manner relative to the hull of the watercraft causes liquid to be expelled from the liquid port into the liquid stream boundary layer and to be drawn into the liquid port from the liquid stream boundary layer.

15. A method in accordance with claim 10 wherein the liquid port constitutes a first liquid port and wherein the step of providing the watercraft occurs in a manner such that the watercraft comprises a second liquid port, the second liquid port allowing liquid communication between the reciprocating member of the watercraft and the liquid environment, the step of propelling the watercraft within the liquid environment occurring by liquid being intermittently expelled from the second fluid port into the liquid environment in response to the moving of the reciprocating member in the linearly reciprocating manner, the moving of the reciprocating member in the linearly reciprocating manner also causing liquid to be intermittently drawn into the second fluid port.

16. A watercraft comprising:

a hull, the hull having an exterior surface;

a reciprocating member, the reciprocating member being operatively connected to the hull in a manner such that the reciprocating member is linearly movable between first and second positions in a reciprocating manner;

a fluid passageway that is partially bound by the reciprocating member; and

an opening through the exterior surface of the hull, the opening forming a portion of the fluid passageway.

17. A watercraft in accordance with claim 16 further comprising an electromagnetic actuator, the electromagnetic actuator being operatively connected to the reciprocating member such that electromagnetic actuator is adapted to drive the reciprocating member back and forth between the first and second positions.

18. A watercraft in accordance with claim 16 wherein the watercraft is surrounded by an external environment and wherein the opening provides the sole fluid connection between the fluid passageway and the external environment.

19. A watercraft in accordance with claim 16 wherein the watercraft is surrounded by an external environment and wherein the watercraft further comprises a valve, the valve being moveable between opened and closed positions, the valve preventing communication between the reciprocating member and the external environment through the opening when the valve is in the closed position, the valve allowing communication between the reciprocating member and the external environment through the opening when the valve is in the opened position.

20. A watercraft in accordance with claim 19 further comprising an electromagnetic actuator, the electromagnetic actuator being operatively connected to the reciprocating member such that electromagnetic actuator is adapted to drive the reciprocating member back and forth between the first and second positions.