Sound transmission in ducts containing nearly choked flowsThe nonlinear theory previously developed by the authors (1977, 1978) is used to obtain numerical results for sound transmission through a nearly choked throat in a variable-area duct. Parametric studies are performed for different source locations, strengths and frequencies. It is shown that the nonlinear interactions in the throat region generate superharmonics of the fundamental (source) frequency throughout the duct. The amplitudes of these superharmonics increase as the source parameters (frequency and strength) are increased toward values leading to acoustic shocks. For a downstream source, superharmonics carry about 20% of the total acoustic power as shocking conditions are approached. For the source strength levels and frequencies considered, streaming effects are negligible.
Document ID
19790042884
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Callegari, A. J. (Joint Inst. for Advancement of Flight Sciences Hampton, VA, United States)
Myers, M. K. (Joint Institute for Advancement of Flight Sciences Hampton, Va., United States)
Date Acquired
August 9, 2013
Publication Date
March 1, 1979
Subject Category
Acoustics
Report/Patent Number
AIAA PAPER 79-0623
Meeting Information
Meeting: American Institute of Aeronautics and Astronautics, Aeroacoustics Conference
Location: Seattle, WA
Start Date: March 12, 1979
End Date: March 14, 1979
Sponsors: American Institute of Aeronautics and Astronautics