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Showing 1 to 20 of 145 for “"Pressure Fluctuations"”.
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Large Eddy Simulation Of Surface Pressure Fluctuations Generated By Elevated Gusts
… velocity events, such as gusts, may trigger pressure fluctuations on the ground. If that is true, it should be possible to monitor elevated wind gusts by measuring these pressure fluctuations. The goal of this project is to develop a ground based detector that monitors the behavior of …
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Effects of a Heated Turbulent Boundary Layer on Surface Pressure Fluctuations
… has shown that spatial correlation of surface pressure fluctuations in a fully turbulent atmospheric boundary layer (ABL) can give information about the velocity field and turbulence. This is of particular importance to the future of wind energy to predict the incoming velocity flow field of …
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Modelling of Wall Pressure Fluctuations Induced by Turbulent Boundary Layer Flow
… 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 when …
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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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An Experimental Investigation of Pressure Fluctuations in Three-Dimensional Turbulent Boundary Layers
… measurements and analysis of the surface pressure fluctuations beneath several turbulent boundary layers of practical interest. Pressure fluctuations in turbulent boundary layers are a source of noise and vibration that can accelerate structural fatigue. Pressure fluctuations and their …
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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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Fluid Dynamics and Surface Pressure Fluctuations of Turbulent Boundary Layers Over Sparse Roughness
… have been performed on a two-dimensional zero pressure gradient turbulent boundary layer over sparsely spaced hemispherical roughness elements of 2 mm diameter. Laser Doppler velocimetry was used to measure all three components of velocity. The friction velocity was calculated using an integral …
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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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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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Investigation Of Pressure Fluctuations In The Hyporheic Zone In Response To Flow Around A Hydraulic Structure
… interface. This study maps hyporheic pressure fluctuations as they are related to surface water velocity. The pressure map is used to evaluate lift enhancement and destabilization forces on the riverbed. High pressure events in the subsurface help generate a destabilizing force from …
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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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An experimental study of the relationship between velocity and pressure fluctuations in a wing-body junction
Velocity and pressure fluctuations were measured in a wind tunnel in the plane of symmetry in front of a wing-body junction at an approach free-stream velocity U<sub>ref</sub>=28.3 m/s and momentum thickness Reynolds number Re<sub>θ</sub>=6900. The cylindrical wing shape was a 3:2 elliptic nose …
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Pressure Fluctuations in a High-Reynolds-Number Turbulent Boundary Layer over Rough Surfaces of Different Configurations
The pressure fluctuations under a high Reynolds Number, rough-wall, turbulent, boundary layer have been studied in the Virginia Tech Stability Wind Tunnel. Rough surfaces of varying element height (1-mm, 3-mm), shape (hemispheres, cylinders) and spacing (5.5-mm, 10.4-mm, 16.5-mm) were investigated …
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Structure of Turbulent Boundary Layers and Surface Pressure Fluctuations on a Patch of Large Roughness Elements
Measurements were made in a zero pressure gradient turbulent boundary layer over two roughness patches containing hemispherical and cubical elements. The elements were 3 mm in height and spaced 16.5 mm apart in an array containing 7 streamwise rows and 6 spanwise columns for a total of 42 elements …
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Some features of surface pressure fluctuations in turbulent boundary layers with zero and favorable pressure gradients
… are interested in the structure of the surface pressure fluctuations for the development and use of noise prediction techniques for helicopter and turbomachinery rotors. This study, conducted in the Virginia Tech low speed boundary layer wind tunnel, covered the effects of zero and favorable …
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The Effects of Pressure Gradient and Roughness on Pressure Fluctuations Beneath High Reynolds Number Boundary Layers
… family of continually varying, bi-directional pressure gradient distributions are investigated in both wind tunnel experiments and steady 2D and 3D Reynolds Averaged-Navier-Stokes (RANS) computations. The effects of pressure gradient, pressure gradient history, roughness, combined roughness and …
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Fluid Dynamics and Surface Pressure Fluctuations of Two-Dimensional Turbulent Boundary Layers Over Densely Distributed Surface Roughness
Measurements were made in two-dimensional zero pressure gradient turbulent boundary layers over 5 geometries of three-dimensional densely distributed surface roughness. A 3-velocity component laser Doppler velocimeter was used to measure instantaneous velocities. These measurements permitted an …
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The mechanism and function of transient pressure fluctuations occurring in the lungs during diving in the turtle, Trachemys (=Pseudemys); scripta elegans
Recurring, brief fluctuations in lung pressure, refered to as Lung Pressure Transiets (LPTs), lasting approximately 5-6 seconds and with an amplitude of +0.25-2.0 mmHg were measured in nearly 30% of all voluntary dives in the aquatic turtle, Trachemys scripta elegans. LPTs were studied to determine …
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