Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 49 for “"Wall Pressure"”.
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Modelling of Wall Pressure Fluctuations Induced by Turbulent Boundary Layer Flow
… used to predict the power spectral density of wall pressure fluctuations in the turbulent boundary layer. From the analysis of current semi-empirical models and a large survey of experimental data, it was found that the models proposed by Goody and Smol'yakov have the lowest mean squared error …
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Boundary Layer Control and Wall-Pressure Fluctuations in a Serpentine Inlet
… by 40.5% (from 1.55% to 0.922%) while the pressure recovery was raised by 9.7% (from 87.2% to 95.6%). With its reduction in distortion, BLC was shown to allow the simulator to steadily operate in a range that would have otherwise been unstable. Minimizing the flow separation within the …
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Normalization of Roughness Noise on the Near-Field Wall Pressure Spectrum
… were taken in the Virginia Tech Anechoic Wall Jet Facility for stochastic rough surfaces varying from hydrodynamically smooth to fully rough as well as deterministic rough surfaces including 1mm and 3mm hemispheres and a 2D wavy wall. Inner and outer variable normalizations were applied to …
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Large-eddy simulation of turbulent wall-pressure fluctuations using the finite element method
In the present dissertation, turbulent wall-pressure fluctuations are characterized. To capture the turbulent characteristics of the flow, large-eddy simulation is used to resolve the large scale motions of the flow directly. A wall-adapting local eddy-viscosity model is selected to account for …
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The Wall Pressure Spectrum of High Reynolds Number Rough-Wall Turbulent Boundary Layers
… layer and the generation of a fluctuating pressure field imposed on the surface. While numerous studies have investigated the wall pressure fluctuations over zero-pressure gradient smooth walls, few studies have examined the effects of surface roughness on the wall pressure field. …
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Turbulent Boundary Layer Superstructures Near the Wall and Their Relationship to Wall-Pressure Fluctuations
… layer as well. They are hypothesized to induce pressure fluctuations upon their interaction with rigid surfaces of various geometrical shapes, surface roughness and other aerodynamic features. Due to their large sizes, they are attributed to the low-wavenumber pressure fluctuations on …
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Characteristics of wall pressure and near-wall velocity in a flat plate turbulent boundary layer
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1988.
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Comparison of techniques to measure the low wavenumber wall pressure spectrum of a turbulent boundary layer
Thesis: Mech. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1984
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Non-Invasive Flow Measurement Via Distributed Acoustic Sensing Utilizing Frequency Spectra Analysis of Wall Pressure Fluctuations
This research describes a method of using distributed acoustic sensing to noninvasively measure volumetric flow rate via multiple unique sensor styles. This work modifies previously used methods of flow detection via fiber optic acoustic sensors affixed onto the exterior body of a flow apparatus. …
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The Rough Wall High Reynolds Number Turbulent Boundary Layer Surface Pressure Spectrum
… been very few studies investigating the rough wall pressure spectra under fully rough flows, which are relevant to many common engineering applications operating within this regime. This investigation uses the Virginia Tech Stability Wind Tunnel to perform experiments on a series of high …
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High Reynolds Number Turbulent Boundary Layer Flow over Small Forward Facing Steps
… 6640 to 213,000. The measurements included mean wall pressure, single and 2 point wall pressure fluctuations, single and 2 point velocity fluctuations and, oil flow visualization. Pressure fluctuation measurements were made 5 boundary layer thicknesses upstream of step to 22 boundary layer …
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Flow Induced Noise from Turbulent Flow over Steps and Gaps
… on a flow surface generate significant pressure fluctuations which can manifest as radiated far field sound and affect the fluctuating near wall pressure field exerted on the flow surface. A significant amount of research has been performed on various step and gap flows; however few have …
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Measurement and Analysis of Sub-Convective Pressure Fluctuations in Turbulent Boundary Layers: A Novel Methodology
… or far-field noise. Decomposing the surface pressure field reveals distinct components, with the sub-convective component being particularly critical due to its coupling with structural modes, inducing vibrations. This component, characterized by wavenumbers lower than convective wavenumbers, …
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The Space-time Structure of an Axisymmetric Turbulent Boundary Layer Ingested by a Rotor
… turbulent boundary layer under a strong adverse pressure gradient is experimentally studied for its relevance to marine applications, urban air-transportation and turbulence ingestion noise. The combined effect of lateral curvature and streamwise pressure gradient are examined on the mean flow, …
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Development of an Engineering Model for Prediction of Ground Shock From Decoupled Detonations
… developed in this effort defines cavity wall loading as a function of scaled distance. The cavity wall pressure, which is strongly influenced by the stagnation of the detonation products, was used to determine peak radial stress in the free-field. A material strength parameter was …
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Space-shuttle windward surface laminar viscous shock-layer flows in equilibrium air at high angles-of-attack
… simulate reentry conditions. The predictions of wall pressure and heat-transfer data compare well with the limited experimental data available requiring relatively short computing times compared to parabolized Navier-Stokes (PNS) methods. Velocity, pressure and enthalpy profiles are compared at …
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Sound from Rough Wall Boundary Layers
… produces sound that radiates outside the near wall region. This noise source is often at a lower level than the noise created by edges and bluff body flows, but for applications with large surface area to perimeter ratios at low Mach number, this noise source can have considerable levels. In …
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A Computational Model of Aneurysmal Flow at the Abdominal Aorta
… that occurs in response to degradation of the wall structure. The present research focused on developing a realistic hemodynamic model of the aneurysm using a new method to assign boundary conditions. A three element Windkessel model was coupled to the 3D geometry model of the disease in order …
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Exploration of Physics-Informed Grid Generation Technique for Wall-Modeled LES using Eagle3D
<p>Wall-Modeled Large Eddy Simulation (WMLES) is an area of interest due to its ability to lower computational costs of LES. Even with the application of wall models, LES still proves to have practicality issues when it comes to use in industry, due to the expertise, time, and computational …
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