An experimental study of the turbulent wake produced by a stern-propellor-driven body moving in a temperature-stratified fluid is presented. The velocity and thermal boundary layers on the body upstream of the propellor are also examined. Mean flow velocities, static pressure, flow angularity and mean temperature distributions are reported at five downstream stations, Z/0 = 0.33, 1 .0, 2.0, 3.0, and 4.0. Turbulence data, including temperature fluctuations are reported at Z/D = 0.33 and Z/D = 4.0. The measurements were taken using thermocouples and pitot tubes of various size, a yawhead probe, a cross-wire hot-wire, and a straight-wire hot-wire as appropriate. For measuring the temperature fluctuations, the straight hot-wire probe was operated in the low-overheat mode to maximize temperature sensitivity. The testing was conducted in the Virginia Tech 6’ X 6’ subsonic wind tunnel at free-stream Re_D = 2.04 X 10⁵. The temperature variation provides a means of tracing the wake development in the near-body region. The principal effect of the propellor is to induce a more or less rigid rotation immediately downstream of the body. The fluid is apparently mixed much less than was anticipated. Temperature fluctuation is mild across the wake except in the vicinity of the propellor tips where it becomes relatively large. The high temperature fluctuation often occurred in regions of low mean temperature gradients which indicates that current modeling techniques should be re-examined. / Ph. D.

A coordinated computational undertaken to investigate the and experimental study was behavior of the vortices trailing from low aspect ratio lifting surfaces. Vortex formation in the near-wake was measured in a wind tunnel with yaw-head and hot-wire probes at three different Reynolds numbers, the highest of which was greater than most previous studies. These near-wake measurements provided initial conditions for the far-field computation with the parabolized Navier-Stokes equations written in terms of vorticity and stream function. Turbulent transport was modeled through the turbulent kinetic energy and the Prandtl-Kolmogorov hypothesis to give an eddy viscosity. The experimental results showed that the effects of Reynolds number are significant for vortex formation in the nearwake, and the computation adequately effects. However, the decay trend in the far-field is essentially unaffected by the Reynolds number, and the predicted decay for maximum tangential velocity agreed very well with Iversen's correlation. / Ph. D.

This thesis has described a Reynolds Averaged Navier Stokes approach to modeling turbulence in the wake of a cylinder and airfoil. The mean flow, cross stresses, and two-point space time correlation structure was analyzed for an untripped cylinder with a Reynolds number based on the cylinder diameter and freestream velocity of 60,000. The same features were also analyzed using this approach for an untripped NACA 0012 airfoil with a Reynolds number based on the airfoil chord and freestream velocity of 328,000. These simulation results were compared to experimental and newly developed models for validation. The ultimate goal of this present study was to create the two-point space time correlation function of a cylinder and airfoil wake using RANS calculations which contributes to a larger study where the sound radiated by an open rotor due to ingestion of turbulence. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1982. / Microfiche copy available in Archives and Barker. / Includes bibliographical references. / by Paul Michael Stremel. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1982. / Microfiche copy available in Archives and Barker / Includes bibliographical references. / by Edward N. Marcus. / M.S.

No description available.

No description available.

Thesis (Ph. D.)--University of Nevada, Reno, 2007. / "March, 2007." Includes bibliographical references (leaves 143-147). Online version available on the World Wide Web.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 53-55).

An experimental investigation was carried out of the flow over a hemisphere-cylinder at angles of attack (α = 0° to 90°, Visualizations of skin-friction lines were conducted and were focused mainly on the development of the laminar separation bubble as a function of angle of attack, the conditions under which open and closed separation exist and the interaction between the separation bubble and the leeward vortices. A digital processing method was developed to convert flow visualizations to numerical data. Static pressure measurements over a large range of Reynolds numbers were obtained for two models with different sizes and the same length-to-diameter ratios. Detailed velocity fields, mapped out by a seven hole probe and a laser-Doppler velocimeter (LDV) probe, were carefully examined to provide information on the development of vortical structures on the surface of the model. Comparisons were made of the results obtained using these two instruments. The flowfield in the wake of the hemispherecylinder was also examined at an angle of attack α = 30°. A small bead was strategically placed near the nose to force vortex asymmetry. Difference sizes of bead were also tested to investigate the effectiveness on the asymmetric pattern. Hot-wire anemometers and a dynamic signal analyzer were employed to study the unsteady motion of leeward vortices. / Ph. D.