Accession Number:

AD0431323

Title:

JET NOISE,

Descriptive Note:

Corporate Author:

ADVISORY GROUP FOR AERONAUTICAL RESEARCH AND DEVELOPMENT PARIS (FRANCE)

Personal Author(s):

Report Date:

1963-04-01

Pagination or Media Count:

33.0

Abstract:

The acoustic efficiency of undisintegrated jets including those associated with aircraft and rockets depends principally on the ratio M of the jet speed to the atmospheric speed of sound, varying approximately as ten to the minus four power by M to the fifth power for low M but being constant about 0.006 for high M, and changing from one form to the other rather abruptly around M2. Improved measurements of jet turbulence and an improved theory of the acoustic radiation from eddies convected at speeds exceeding the atmospheric sound speed are used to show how this form of acoustic efficiency variation, and the associated changes in directional distribution and frequency spectrum, can be explained in terms of a comprehensive theory, which represents a jet as a distribution of acoustic quadrupoles in an otherwise undisturbed atmosphere, the quadrupole strengths being well correlated only within convected eddies of limited extent and limited lifetime. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE