Acoustic Receptivity Due to Weak Surface Inhomogeneities in Adverse Pressure Gradient Boundary Layers

Acoustic Receptivity Due to Weak Surface Inhomogeneities in Adverse Pressure Gradient Boundary Layers PDF Author: Meelan Choudhari
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 44

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Acoustic Receptivity Due to Weak Surface Inhomogeneities in Adverse Pressure Gradient Boundary Layers

Acoustic Receptivity Due to Weak Surface Inhomogeneities in Adverse Pressure Gradient Boundary Layers PDF Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781729376409
Category : Science
Languages : en
Pages : 44

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The boundary layer receptivity to free-stream acoustic waves in the presence of localized surface disturbances is studied for the case of incompressible Falkner-Skan flows with adverse pressure gradients. These boundary layers are unstable to both viscous and inviscid (i.e., inflectional) modes, and the finite Reynolds number extension of the Goldstein-Ruban theory provides a convenient method to compare the efficiency of the localized receptivity processes in these two cases. The value of the efficiency function related to the receptivity caused by localized distortions in surface geometry is relatively insensitive to the type of instability mechanism, provided that the same reference length scale is used to normalize the efficiency function for each type of instability. In contrast, when the receptivity is induced by variations in wall suction velocity or in wall admittance distribution, the magnitudes of the related efficiency functions, as well as the resulting coupling coefficients, are smaller for inflectional (i.e., Rayleigh) modes than for the viscous Tollmien-Schlichting waves. The reduced levels of receptivity can be attributed mainly to the shorter wavelengths and higher frequencies of the inflectional modes. Because the most critical band of frequencies shifts toward higher values, the overall efficiency of the wall suction- and the wall admittance-induced receptivity decreases with an increase in the adverse pressure gradient. Choudhari, Meelan and Ng, Lian and Streett, Craig Langley Research Center NAS1-18240; NAS1-18599; RTOP 537-03-23-03...

Monthly Catalog of United States Government Publications

Monthly Catalog of United States Government Publications PDF Author:
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Category : Government publications
Languages : en
Pages : 1034

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Monthly Catalogue, United States Public Documents

Monthly Catalogue, United States Public Documents PDF Author:
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Category : Government publications
Languages : en
Pages : 856

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Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports PDF Author:
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Category : Aeronautics
Languages : en
Pages : 692

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New Results in Numerical and Experimental Fluid Mechanics III

New Results in Numerical and Experimental Fluid Mechanics III PDF Author: Siegfried Wagner
Publisher: Springer Science & Business Media
ISBN: 9783540426967
Category : Technology & Engineering
Languages : en
Pages : 458

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This volume contains the papers of a German symposium dealing with research and project work in numerical and experimental aerodynamics and fluidmechanics for aerospace and other applications. It gives a broad overview over the ongoing work in this field in Germany.

NASA Langley Scientific and Technical Information Output, 1995

NASA Langley Scientific and Technical Information Output, 1995 PDF Author:
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Category : Astronautics
Languages : en
Pages : 172

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This document is a compilation of the scientific and technical information that the Langley Research Center has produced during the calendar year 1995. Included are citations for formal reports, high-numbered conference publications, high-numbered technical memorandums, contractor reports, journal articles and other publications, meeting presentations, technical talks, computer programs, tech briefs, and patents.

The Aeronautical Journal

The Aeronautical Journal PDF Author:
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Category : Aeronautics
Languages : en
Pages : 522

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NASA Technical Memorandum

NASA Technical Memorandum PDF Author:
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Category : Aeronautics
Languages : en
Pages : 176

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Aeronautical Engineering: A Cumulative Index to a Continuing Bibliography (supplement 325)

Aeronautical Engineering: A Cumulative Index to a Continuing Bibliography (supplement 325) PDF Author:
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ISBN:
Category :
Languages : en
Pages : 470

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