George R. Douglas

Transducer assembly for self-calibration

An acoustic homing torpedo having an array of transducers wherein each transducer has a head mass, tail mass, and a main active element therebetween. An auxiliary active element is placed on the tail mass so that when given a predetermined signal it will cause the main element to provide a corresponding output signal so as to simulate the reception of an actual acoustic wave. By energizing the main element, the response of the auxiliary element may be examined for testing the transducer and the array in a transmit mode of operation.

Low frequency dipole hydrophone transducer

A dipole hydrophone which includes a radiation target for acoustic energy and a counterbalancing mass. A first multilaminar magnetostrictive arm is connected to the radiation target at its center gravity and a second multilaminar magnetostrictive arm is similarly connected to the center of gravity of the counterbalancing mass. The lower portion of each arm is slotted to define two legs, and a permanent magnet, in conjunction with the slotted structure forms a closed magnetic path for flux. Windings for sensing a change in flux are slipped over the leg portions, yielding a high gain device. The two arms are connected by a coupling member which is compliantly suspended from a support structure.

Tonpilz head mass studies

Alumina and composites of graphite/epoxy were used as head mass materials in two separate applications. In the first application alumina and composites of graphite/epoxy head masses were used to produce a low mechanical Q, high electroacoustic efficiency transducer. The initial results show that graphite/epoxy composites especially have great promise as head mass material because of its light weight and high tensile strength. In the second application an alumina head mass was used in a dual mode transducer. This configuration consists of an array of smaller tonpilz elements mounted in the head mass of larger tonpilz elements. This unique method required a very stiff secondary head mass to transfer acoustic energy (without storing strain energy) to the primary radiating surface of the smaller elements. Work in first application was sponsored by Westinghouse in‐house R&D Program of FY 81 & 82. [The work in second application was supported by the dual mode transducer program Navy contract No. N00140‐80‐R‐6916.]

Acceleration canceling pressure gradient hydrophone

An acceleration canceling pressure gradient hydrophone is described. The unique difference between the conventional pressure gradient hydrophone and the current phone is a plumbing and counterweight arrangement whereby acceleration induced forces from the enclosed fluid are balanced by counterweight forces. Cancelation ratios of 35 dB flat from 10 Hz up are reported from tank measurements. One axis decoupling techniques are described to enhance this ratio at 12 dB/octave from decoupler resonance. The effects of some hydrophone outer housings on the decoupler are shown. Three field tests are described: two using a new radial arm device in a quiet lake, and one using a bottom mounted cable in a tidal estuary. The first radial arm test indicated a cross‐over between structure borne and turbulent boundary layer noise as flow rates rise above about 12knot. The tidal estuary test showed large enhancements of gradient acoustic output near irregular boundaries. This is attributed to the excess pressure gradients ...