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 57 for “"turbulence intensities"”.
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Split-film anemometry in a drag-reducing solution
<p>"Turbulence measurements were made in the tube flow of mineral oil and a 0.2% solution of polyisobutylene in the same oil. Velocity profiles, axial and radial turbulence intensities, and axial and radial energy spectra were obtained in both fluids using a split-film anemometer probe. In …
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Effects Of Large-Scale Free Stream Turbulence On A Turbulent Boundary Layer
… there are systematic variations of free stream turbulence above a flat plate boundary layer are presented. Upstream of the plate, an active grid generates free stream turbulence varying in intensity from 0.25% to 10.5%. The momentum thickness Reynolds number of the boundary layer varies from 550 …
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The Effect of Freestream Turbulence on Separation at Low Reynolds Numbers in a Compressor Cascade
… to observe and quantify the effect of varying turbulence intensities on separation and performance in a compressor cascade at low Reynolds numbers. Tests were performed at 25° and 37.5° stagger angle, negative and positive angles of incidence up until the point of full stall, Reynolds numbers …
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A Study of Compressible Turbulent Free Shear Layers Using Laser Doppler Velocimetry (Supersonic Flow, Mixing, Recirculating)
… measurements were made. Streamwise component turbulence intensities were found to be comparable to incompressible mixing layer results which contrasts with the limited existing hot-wire anemometer data. Transverse velocity component turbulence intensities, turbulence shear stresses, shear …
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Experimental Investigation of Wind Loading on a Ducted Wind Turbine
… To enhance our understanding on the impacts of turbulence on the loading of a ducted wind turbine, an experimental analysis with changing upstream turbulence characteristics was undertaken. One fourth scaled model of an aerofoiled shaped duct (Donqi Urban Windmills) loaded with an actuator disc …
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Turbulence measurements in drag reducing flow
… are not valid for wedge probes. The structure of turbulence in drag reducing soap and polymer solutions was studied using a hot-film wedge probe. Intensity of turbulence measurements in drag reducing fluids indicate that the structure of trubulence is strongly dependent on the condition of the …
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Airflow Analysis in Mechanically Ventilated Obstructed Rooms
… combination. However, average air velocities and turbulence intensities were not influenced by obstruction setups or inlet configurations. The decay rate of mean velocity kinetic energy in the bulk flow region was independent of obstructions and inlets. Room average kinetic energy was a function …
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Influence of initial turbulence intensity on the heat and moisture transfer through a recirculated air curtain
… which accounts for the influence of the initial turbulence intensity on the transfer of heat and moisture across a recirculated air curtain. The control of the turbulence intensity at the nozzle exit of an air curtain permits control of heat and moisture transfer and therefore the energy required …
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Macroscopic Turbulence Modeling and Simulation for Flow Through Porous Media
… out for 75% and 95% porosities. Different inlet turbulence intensities are imposed on the free stream to test the model under different macroscopic boundary conditions. Microscopic RANS solutions for the turbulence quantities ( k and &egr;) are averaged in space and compared with those yielded by …
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Numerical investigation of the influence of elevated turbulence levels on the cooling effectiveness of an anti-vortex hole geometry
… a commercial CFD code (STAR-CCM+) with varying turbulence intensity and length scale using the k-o SST turbulence model. Both steady and unsteady results were considered in order to investigate the effects of freestream turbulence intensity and length scale on this novel anti-vortex hole (AVH) …
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Experimental Investigation Of The Effect Of Turbulence On Slot-Fed Film Cooling Adiabatic Effectiveness And Downstream Heat Transfer
… burn at different temperatures, have different turbulence intensities in the flow, and require different amount of cooling. Research has been done in the past to determine some of the parameters that affect film cooling performance. The purpose of this research was to determine the effects of …
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Aspirating probes for measurement of mean concentration and fluctuating quantities in supersonic air/helium shear layer
… composition, this second probe also measures turbulence intensities of Reynolds number and thermal conductivity using a multiple overheat method. This probe is referred to as the turbulent probe. Both probes are used in the study of supersonic air/helium mixing layers in the VPI&SU 23 cmx23 cm …
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Mean flow and turbulence measurements in the wake of a slender propeller-driven body including effects of pitch angle
… static pressure, flow angularity, and turbulence quantities are presented at three downstream stations Z/D = 2, 10, and 40. The measurements were taken using a yawhead pressure probe and hot-wire sensors. The testing was conducted in the Virginia Tech 6-foot subsonic tunnel at …
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The use of hot-wire anemometry in studying supersonic slot injection into a supersonic flow
… as well as the temperature and mass flux turbulence intensities. The probe can be used anywhere except at locations where features of the flow are smaller than the separation between the wires (0.18 mm). The calibration of the probe can be repeated with less than a three percent change in …
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Measurements of pressure and thermal wakes in a transonic turbine cascade
The effects of freestream turbulence on the total pressure and total temperature in the wake of a cooled transonic turbine cascade with heated flow are presented in this thesis. The experiment was conducted in the Virginia Tech Cascade Wind Tunnel. A dual hot wire aspirating probe was used to make …
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Experimental investigation of the impact of the permeable layer thickness on the surface flow above and the threshold for incipient motion of submerged objects
… above, specifically, the mean velocity profiles, turbulence intensities, and flow resistance? (2) How does the presence of bed permeability as well as the thickness of the permeable bed affect the threshold for incipient motion of submerged spheres and cylinders? The experiments involved two …
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Local flowfield about large distributed roughness elements in a laminar boundary layer
… time-averaged three-dimensional velocities, turbulence intensities, and vorticity were all calculated from the measured velocities. Fluorescent-oil flow and laser-sheet/smoke-wire flow visualization data were obtained in order to help qualitatively explain the flowfield.
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Flow through Rigid Vegetation Hydrodynamics
… within the canopy to develop velocity and turbulence intensity profiles and observe the changes in the flow characteristics as water travels through a vegetation array simulated by rigid dowels. Velocity data were collected with a one dimensional laser Doppler velocimeter (LDV) under single …
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Experimental simulation of the wake of an axisymmetric body near a free surface
… to influence the magnitudes and radial spread of turbulence intensities and Reynolds stresses. Some interactions between the wake of the axisymmetric body and that of the plate strut were observed. Overall, the mean velocities and the turbulence quantities indicated symmetry about the image plane …
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Wavelet Analysis of Extreme Wind Loads on Low-Rise Structures
… geometric and dynamic similitudes. Some turbulence parameters that have been considered in many simulations include, turbulence intensities, integral length scales, surface roughness, and frequency spectrum. One problem with these parameters is that they are time varying in the …
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