Shock wave interactions with turbulence and vortices.
Item
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Title
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Shock wave interactions with turbulence and vortices.
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Identifier
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AAI9908290
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identifier
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9908290
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Creator
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Agui, Juan Humberto.
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Contributor
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Adviser: Yiannis Andreopoulos
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Date
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1998
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Mechanical | Applied Mechanics
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Abstract
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The interactions of a planar shock wave with an induced vortical, vortex dominated and turbulence dominated, flow have been investigated experimentally in the CCNY Shock Tube Research Facility (STURF). Time-dependent measurements of total pressure, total temperature, three-dimensional velocity and vorticity were undertaken. A custom made hot-wire vorticity probe for non-isothermal flows was successfully validated in a turbulent boundary layer prior to its use for measurements of the interactions.;Three types of interactions were investigated through the use of various grid and wing models to produce: (1) turbulence - shock wave, (2) streamwise vortex - shock wave, and (3) spanwise vortex - shock wave interactions. Analysis of the turbulence - shock wave interaction revealed that fluctuations in longitudinal velocity and spanwise and normal vorticity were amplified most through the interaction. Wavenumber spectral amplification showed that all velocity and vorticity fluctuations were amplified mostly in the large wavenumber range. After interaction the enstrophy spectra gave the clearest evidence that there was a shift in rotational energy to higher wavenumbers. Examination of the stretching signals demonstrated the bursting behavior of the stretching process. Enhanced stretching fluctuations and bursting behavior was found in most cases after interaction.;The effects of the shock wave on a concentrated streamwise vortex were more dramatic producing a two fold increase in the vorticity fluctuations at the two investigated Mach numbers. Wavenumber spectra of longitudinal vorticity indicated that most of the energy resided in the small wavenumbers, with a shift to higher wavenumbers after interaction. Particle Flow Visualization images provided evidence of core growth through the interaction.;The spanwise vortex - shock wave interaction indicated that significant vortex distortion and/or tilting of the vortex axis occurred through the interaction. The signals of spanwise vorticity through the uncompressed vortex strongly indicated larger fluctuations in on leading part of the vortex as it propagated downstream which were tied to larger fluctuations in the normal velocity. The flow visualization images provided some physical insight into this turbulent structure. These images also indicated the existence of longitudinal roll structures.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
