Apparatuses and methods for sound absorption using hollow beads

Details Apparatuses and methods for sound absorption using hollow beads Apparatuses and methods for sound absorption using hollow beads

1995-03-27

1998-07-07

Pihulic, Daniel T.

Communications, electrical: acoustic wave systems and devices

Sonar counter-measures

367191, 181256, 60322, F01N 124

Patent

active

057779473

ABSTRACT:
A sound absorption device in accordance with this invention includes an enclosure loosely containing hollow beads. Preferably, the hollow beads have openings, and differ with respect to the volume of the hollow space defined by the walls of the beads, the wall thicknesses of the beads, the size of the openings of the beads and/or the number of openings on the beads. Through Helmholtz resonance, vorticity and tortuous path scattering, the beads damp sound waves over a broad range of frequencies. Preferably, the beads are formed from a material able to withstand relatively high temperatures, such as ceramic or nickel. The beads can thus be used to damp sound in applications which generate significant heat in addition to sound, such as aircraft engines, rocket motors or other loud, heat-generating sources, for example. Also, by forming the beads from a material with a relatively low thermal conductivity, the beads can also be used for thermal insulation in addition to sound absorption.

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AeroSpheres, An attractive new alternative for the high-temperature, engineered materials market, Ceramic Fillers, Inc.
Thin-Wall Hollow Spheres From Slurries and Thermally Insulating Materials -- Model & Measure, Ceramic Fillers, Inc.

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