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.
Results
Showing 1 to 20 of 20 for “"surface pressure fluctuations"”.
-
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 …
-
Effects of a Heated Turbulent Boundary Layer on Surface Pressure Fluctuations
Recent work 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 …
-
Fluid Dynamics and Surface Pressure Fluctuations of Turbulent Boundary Layers Over Sparse Roughness
Turbulent boundary layers over rough surfaces are a common, yet often overlooked, problem of practical engineering importance. Development of correlations between boundary layer parameters that can be used in turbulence models and the surface geometry is the only practical option for solving these …
-
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 …
-
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 …
-
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 …
-
Mean Loading and Turbulence Scale Effects on the Surface Pressure Fluctuations Occurring on a NACA 0015 Airfoil Immersed in Grid Generated Turbulence
Detailed surface pressure measurements have been made on a NACA 0015 immersed in two grid generated homogenous flows at Re = 1.17 x 10⁶ for a = 0°, 4°, 8°, 12°, 16°, and 20°. The goal of this measurement was to reveal and highlight mean loading and turbulence scale effects on surface pressure …
-
An Experimental Investigation of Pressure Fluctuations in Three-Dimensional Turbulent Boundary Layers
… experimental 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 …
-
Pressure Shielding Mechanisms in Bio-Inspired Unidirectional Canopy Surface Treatments
Reduction of surface pressure fluctuations is desirable in various aerodynamic and hydrodynamic applications. Over the past few years, studies on canopy surface treatments have been conducted to investigate the fundamental mechanisms of surface pressure attenuation termed as pressure shielding. …
-
Measurements in the bimodal region of a wing-body junction flow with a rapidly-scanning two-velocity-component laser-Doppler velocimeter
… components were measured simultaneously with surface pressure measurements at the location of the most bimodal pressure histogram (x/t=-0.26). Mean (U, V) and rms (u’, v’) velocity components were obtained at four x locations, x/t= -0.15, -0.20, -0.25, -0.30, and show the same flow features …
-
Ice-Induced Unsteady Flowfield Effects on Airfoil Performance
… were presumed to be the cause of large-scale pressure fluctuations upstream of reattachment at small angles of attack. Pressure spectra near reattachment exhibited wide bandwidth frequency peaks that indicated a non-periodic phenomenon and corresponded to the regular mode often associated with …
-
Vorticity Modeling for the Flow Over Surface-Mounted Prisms
… modeling is used to simulate the flow around a surface-mounted prism. The objective is to examine whether vorticity modeling can give satisfactory information about surface pressure fluctuations which are mostly due to the outer or inviscid flow. Differences between results obtained with …
-
Airfoil-vortex interaction and the wake of an oscillating airfoil
… was evaluated throughout the interaction. The surface pressure fluctuations on the airfoil were determined by substituting the measured velocities into the Navier-Stokes equations and numerically integrating the resulting pressure gradients. Furthermore, an extensive investigation of the …
-
Optimal design of municipal and irrigation water distribution systems
… flow, the point of flow separation from the surface coincides with the point at which the skin friction vanishes. However, in three-dimensional flow, the situation is much more complex and the flow separation is rarely associated with the vanishing of the wall shear stress except in a few …
-
Wall Jet Boundary Layer Flows Over Smooth and Rough Surfaces
The aerodynamic flow and fluctuating surface pressure of a plane, turbulent, two-dimensional wall jet flow into still air over smooth and rough surfaces has been investigated in a recently constructed wall jet wind tunnel testing facility. The facility has been shown to produce a wall jet flow with …
-
Wall Features of Wing-Body Junctions: Towards Noise Reduction
… have been found to generate regions of high surface pressure fluctuations and turbulence that are detrimental to structural components and acoustics. With the focus in the military and commercial industry on reducing the acoustical impact of aircraft and their engines, very little research …
-
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 …
-
The Rough Wall High Reynolds Number Turbulent Boundary Layer Surface Pressure Spectrum
… 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 Reynolds …
-
Study of Far Wake of a Surface-Mounted Obstacle Subjected to Turbulent Boundary Layer Flows
… conducted with and without the presence of the surface-mounted obstacle to quantify its effects on the far wake. The obstacle chosen for this study was a 3:2 elliptical nose NACA 0020 tail wing-body (Rood body), approximately of height equal to the boundary layer thickness at one of the …
-
Sound Radiated from Turbulent Flow over Two and Three-Dimensional Surface Discontinuities
… layer flow over two and three-dimensional surface discontinuities whose height is smaller than the incoming boundary layer thickness. The work was performed in two different types of boundary layers: a wall-jet flow and a conventional high Reynolds boundary layer. In the wall-jet flow, …