Generation of low frequency sound under water

Claim 2

Apparatus for the generation of sound under water including a siren comprising a cylindrical stator casing open at each end and having at least one radial port and a cylindrical rotor member open at each end and mounted concentrically with respect to said stator casing, said rotor member having at least one radial opening circumferentially alined with said stator port, and a gas-filled compliance chamber having an elastic rubberlike wall closing one open end of said stator casing and operative to store and release hydraulic energy.

Claim 3

Apparatus in accordance with claim 1 wherein said stator casing is provided with two diametrically opposed radial ports and said rotor member is provided with two radial openings which match said eradial ports.

Claim 4

Apparatus in accordance with claim 1 including a foraminous guard means between said elastic wall and said one open end of said stator casing for limiting the excursion of said elastic wall in the direction of increasing volume of said compliance chamber.

Claim 5

Underwater sound generating apparatus of the siren type comprising a drum type rotor, a cylindrical stator member surrounding said rotor, said rotor and said stator member having circumferentially spaced ports adapted to aline periodically upon rotation of the rotor, and an auxiliary rotor of the drum type concentric with said stator member and having openings distributed throughout its circumference so that at all angular positions of said auxiliary rotor at least one of said distributed openings is aligned with each of said stator ports, said auxiliary rotor being positioned within said drum type rotor and said distributed openings being of different area whereby rotation of said auxiliary rotor varies the effective area of said stator ports in a predetermined manner.

Claim 6

Underwater sound generating apparatus of the siren type comprising a drum type rotor, a cylindrical stator member surrounding said rotor, said rotor and said stator member having circumferentially spaced ports adapted to aline periodically upon rotation of the rotor, and an auxiliary rotor of the drum type concentric with said stator member and having openings distributed throughout its circumference so that at all angular positions of said auxiliary rotor at least one of said distributed openings is aligned with each of said stator ports, said auxiliary rotor being positioned within said drum type rotor and said distributed openings being of different area whereby rotation of said auxiliary rotor varies the effective area of said stator ports in a predetermined manner.

Claim 7

Underwater sound generating apparatus of the kind described wherein water is pumped axially into an underwater siren of the drum type and is discharged radially in successive slugs through ports in an external stator when said ports are temporarily opened and abruptly closed intermittently by an internal rotor member, the acceleration of each slug of water being sufficient to draw out a cavity when its associated port is abruptly closed, characterized by said stator ports having walls defining horn-shape channels to constrain cavity formation and collapse to substantially a single direction, said channels increasing gradually in cross-sectional area with length and having a volume substantially equal to the volume of the cavity formed, and the walls of said stator ports having at least one lateral passageway between the base of the port and the open water for the entry of water to lessen cavitation erosion of the surface of said rotor member.

Claim 8

Underwater sound generating apparatus of the kind described wherein water is pumped axially into an underwater siren of the drum type and is discharged radially in successive slugs through ports in an external stator when said ports are temporarily opened and abruptly closed intermittently by an internal rotor member, the acceleration of each slug of water being sufficient to draw out a cavity when its associated port is abruptly closed, characterized by said stator ports having walls defining horn-shape channels to constrain cavity formation and collapse to substantially a single direction, said channels increasing gradually in cross-sectional area with length and having a volume substantially equal to the volume of the cavity formed, and the walls of said stator ports having at least one lateral passageway between the base of the port and the open water for the entry of water to lessen cavitation erosion of the surface of said rotor member.