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Fundamental Aspects of the Structure of Supersonic Turbulent Boundary

Author : Jonathan H. Watmuff

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Page : 41 pages

File Size : 40,8 MB

Release : 1987

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Book Description

Measurements of structure angle in a supersonic turbulent boundary layer with zero and adverse pressure gradients are presented. Conditionally sampled measurements of u, v, and uv are presented along with quadrant analysis of the turbulent fluctuations. The latter suggests ambiguities associated with the interpretation of VITA measurements. Preliminary results of experiments on artificially generated hairpin vortices are also discussed. Measurements indicate a high degree of similarity between the signatures of these hairpin structures and ensemble averaged events in the turbulent boundary layer. Keywords: Turbulence, Boundary layer, Supersonic Flow.



Physical Models for Supersonic Turbulent Boundary Layer Structure

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Page : 32 pages

File Size : 45,50 MB

Release : 1989

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An experimental program was carried out to study the detailed structure of supersonic turbulent boundary layers. The experiments were designed to elucidate physical models and mechanisms that are particular to compressible turbulence, such as the effects of compressibility on the nature of the large- scale motions, the scaling laws for high Reynolds number supersonic turbulent flows, direct compressibility effects that cause the exchange of turbulence energy among the vorticity, entropy and sound modes, and the transport of heat and momentum by compressible turbulent motions. A description of the new optical experimental tools that were developed is included. (EDC).



On the Coupling Between a Supersonic Turbulent Boundary Layer and a Flexible Structure

Author : National Aeronautics and Space Administration (NASA)

Publisher : Createspace Independent Publishing Platform

Page : 44 pages

File Size : 13,31 MB

Release : 2018-07-09

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ISBN : 9781722453923

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Book Description

A mathematical model and a computer code have been developed to fully couple the vibration of an aircraft fuselage panel to the surrounding flow field, turbulent boundary layer and acoustic fluid. The turbulent boundary layer model is derived using a triple decomposition of the flow variables and applying a conditional averaging to the resulting equations. Linearized panel and acoustic equations are used. Results from this model are in good agreement with existing experimental and numerical data. It is shown that in the supersonic regime, full coupling of the flexible panel leads to lower response and radiation from the panel. This is believed to be due to an increase in acoustic damping on the panel in this regime. Increasing the Mach number increases the acoustic damping, which is in agreement with earlier work. Frendi, Abdelkader Unspecified Center NAS1-19700; RTOP 537-06-37-20...