Transient Acoustical Sources in an Idealized Jet
作者:
E. W. Graham,
B. B. Graham,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1972)
卷期:
Volume 52,
issue 1B
页码: 221-226
ISSN:0001-4966
年代: 1972
DOI:10.1121/1.1913083
出版商: Acoustical Society of America
数据来源: AIP
摘要:
The transmission of acoustic disturbances from the interior of the jet through the mean velocity profile and into the farfield is studied in detail. The noise generator is taken to be a sequence of transient acoustical point sources traveling with the local fluid in the idealized jet. The idealized jet is two‐dimensional, and extends to infinity upstream and downstream with velocity profile independent of streamwise position. For the limited set of examples considered the following conclusions apply: (1) Velocity profile has a large effect on the magnitude of the noise radiated to the farfield. (2) Much of the farfield noise, especially at low Strouhal numbers, originates not as true waves but in the form of acoustical disturbances within the jet which are not radiating energy. (3) At subsonic velocities, the characteristic lobes appearing in a polar plot of farfield mean‐square pressure approach the downstream axis as frequency decreases. This somewhat resembles experimental trends, but many other factors must be considered before a valid comparison can be made.
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