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Downstream boundary effects on the frequency of self-excited oscillations in transonic diffuser flowsAn investigation of downstream boundary effects on the frequency of self-excited oscillations in two-dimensional, separated transonic diffuser flows has been conducted numerically by solving the compressible, Reynolds-averaged, thin-layer Navier-Stokes equation with a two-equation turbulence model. It was found that the unsteady diffuser flowfields are very sensitive to the location of the downstream boundary. Extension of the diffuser downstream boundary significantly reduces the frequency and amplitude of oscillations for pressure, velocity and shock. Computational results suggest that the mechanism causing the self-excited oscillation changes from viscous convective wave dominated oscillations to inviscid acoustic wave dominated oscillations when the location of downstream boundary varies from 8.66 to 134.7 throat height. The existence of a suction slot in the experimental setup obscures the physical downstream boundary and, therefore, presents a difficulty for quantitative comparisons between computation and experiment.
Document ID
19870035177
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Hsieh, T.
(U.S. Navy, Naval Surface Weapons Center Silver Spring, MD, United States)
Coakley, T. J.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 13, 2013
Publication Date
January 1, 1987
Subject Category
Aerodynamics
Report/Patent Number
AIAA PAPER 87-0161
Accession Number
87A22451
Distribution Limits
Public
Copyright
Other

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