Accession Number:

AD0645111

Title:

EFFECTIVENESS OF ELASTIC-WALLED CONCENTRIC TUBES IN ATTENUATING FLUIDBORNE NOISE IN AN EXPANSION CHAMBER ACOUSTIC FILTER,

Descriptive Note:

Corporate Author:

NAVY MARINE ENGINEERING LAB ANNAPOLIS MD

Personal Author(s):

Report Date:

1966-12-01

Pagination or Media Count:

130.0

Abstract:

The report describes an experimental evaluation of several internal design modifications intended to improve the fluidborne noise reduction provided by an expansion-chamber type acoustic filter over the frequency range of 40 to 1000 Hertz Hz modifications included The installation of a number of combinations of elastic-walled tubes concentrically positioned in the expansion chamber. A set of many small diameter orifices drilled in two of the concentrically positioned tubes. A baffle installed at the inlet end of the expansion chamber between a single concentric tube and the expansion chamber wall. Results indicate no consistent trends or order relating attenuation and the number of concentric elastic-walled tubes in the expansion chamber, over the frequency range of interest. A significant improvement in attenuation over that obtained by the expansion chamber alone was noted, however, when the smaller of the two tubes having drilled orifices was installed. Installation of a baffle brought further improvement in attenuation. Author

Subject Categories:

  • Submarine Engineering
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE