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 15 of 15 for “"velocity spectra"”.
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Flowfield Downstream of a Compressor Cascade with Tip Leakage
… sensor hot-wire anemometers, from which the mean velocity field , the turbulence stress field and velocity spectra were obtained. Oil flow visualizations were done on the endwall underneath the blade row. Also studied were the effects of tip gap height, and blade boundary layer trip variations. …
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Prediction of seismic design response spectra using ground characteristics
… For the groups thus defined, normalized response spectra are obtained for single-degree-of-freedom and massless oscillators. The effectiveness of the grouping scheme is examined by studying the variance of response quantities within each group. The implicit parameters of average frequency and …
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An investigation of drone propeller noise generation in a turbulent wake
… between 3500 RPM and 5000 RPM at a freestream velocity of 15 m/s. The inflow disturbance upstream of the propeller is the wake of a NACA0012 profile wing to which the propeller is mounted simulating a UAV in pusher configuration. Hot-wire anemometry is used to characterise the wake of the …
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Turbulent Boundary Layers over Rough Surfaces: Large Structure Velocity Scaling and Driver Implications for Acoustic Metamaterials
… laws were implemented in attempts to collapse velocity spectra and turbulence profiles. Such analyses were performed to justify a proper scaling of the low-frequency region of the wall-pressure spectrum. Such frequencies are commonly associated with eddies containing the largest length scales. …
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Accuracy of Noninvasively Determined Pulmonary Artery Pressure in Dogs With Myxomatous Mitral Valve Disease
… the simplified Bernoulli equation to the velocity of tricuspid regurgitation (sPAP_D). The accuracy of this estimation is unknown in dogs with MMVD, but experimental studies suggest that the method is imperfect. In order to fill this knowledge gap we prospectively enrolled dogs affected by …
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Structure of Turbulent Boundary Layers and Surface Pressure Fluctuations on a Patch of Large Roughness Elements
… was a large amount at k/δ = 20. A three velocity component laser Doppler velocimeter measured instantaneous velocities. Mean flow and turbulence statistics were calculated as well velocity energy spectra. Surface pressure fluctuations were measured using a two-microphone subtraction …
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Ridge waves
… effort to explain subinertial peaks found in the velocity spectra over the Juan de Fuca Ridge (JdFR, 4 days) and the Iceland-Faeroe Ridge (IFR, 1.8 days). Topographic cross sections of the ridges are fit by a double-exponential depth profile and the linearized shallow water equations are solved …
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Hydrogen Enrichment Effects on Thermoacoustics of Turbulent Partially Premixed Flames
… and chaotic states, as either bulk velocity or equivalence ratio is varied. The unstable acoustic modes and their spatial behaviour are investigated using a reduced-order model. This thesis also addresses the challenge of modelling direct combustion noise, essential for mitigating …
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The properties of transiting exoplanets
… Gaia DR2 parallax distance, and WHT/LIRIS NIR spectra. I also statistically validated the planet candidate (planet e) – a fourth super-Earth in the system. This new planet orbits on the edge of the star’s temperate zone and prompts discussion on its potential composition and habitability. …
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Broadband Noise Prediction of an Axial Compressor Operating at Low Reynolds Number
… a fine resolution was needed for convergence of velocity and pressure spectra describing acoustic sources, a relatively coarse LES could still provide similar estimates of second order statistics such as Reynolds stresses. When compared to experiment, the LES results show a pleasing ability to …
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Dynamics of cloud-top generating cells in winter cyclones
… was evident in the daytime simulation’s vertical velocity spectrum, with the 99th percentile of vertical velocity in the 6 – 8 km layer of 1.2 m s-1, compared to 1.8 m s-1 for the nighttime simulation. GCs regenerate in simulations with radiative forcing after the initial stability is released, …
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Unsteady flow physics of airfoil dynamic stall
… the lower Reynolds numbers. The time-dependent spectra of the velocity field were calculated using a combination of empirical mode decomposition and Hilbert transformation. From the velocity spectra, the fluctuations in the flow were observed to attain an amplified state during the initial …
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Design of Active Structure Acoustic Control Systems Using Eigenassignment Approach
… wavenumber components of the structural velocity spectra radiate to the far field. A SISO eigenassignment technique is used to modify the eigenproperties of a planar structure so that the eigenfunctions of the controlled system have minimum supersonic wavenumber in the frequency range of …
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Wall Jet Boundary Layer Flows Over Smooth and Rough Surfaces
… with the roughness grain size, but the maximum velocity, mixing layer length scale, y<SUB>/2</SUB>, and the boundary layer thickness were not seen to vary in a consistent, determinable way. Velocity spectra taken at a range of initial flow conditions and at several distinct heights above the …
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Large Eddy Simulation of Shear-Free Interaction of Homogeneous Turbulence with a Flat-Plate Cascade
… Because suppression of the normal component of velocity is the main mechanism of distortion, we neglect the presence of mean shear in the boundary layers and wakes, and allow slip velocity on the plate surfaces. We enforce the zero normal velocity condition on the plates. This boundary condition …