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 41 for “"Wake region"”.
-
Effect of Passive Clean Air Injection Into the Wake Region of a Moving Ground Vehicle
<p>The wake region on a moving ground vehicle is responsible for 70% of the aerodynamic drag when the speed of 90km/h is achieved. The topic of wake region manipulation has been revisited multiple times and with varying techniques. When manipulating the flow utilizing a fully passive method, …
-
Time-resolved heat transfer measurements and analysis in the wake region of a cylinder in crossflow
… entire cylinder. In the attached boundary layer region, the heat flux signal was sinusoidal at the shedding frequency for the steady cases and at the driving frequency for the pulsating case. In the wake, however, the fluctuations were less organized in all cases. Here the magnitude of the …
-
Circulation control for download wake reduction on a scaled V-22 model
… wing to reduce the size of the download in the wake region brought upon by the airflow from the proprotors. The techniques being used in this experiment are the implementation of blowing slots across the leading edge and trailing edge, activation of one or both of the blowing devices, and …
-
Flow Visualizations and Measurements of Turbulent Structures in Drag-Altered Axisymmetric Compressible Base Flows
… present in the recompression and reattachment regions of the flowfield are shown to de-stabilize the turbulent structure organization. The mean structure statistics of all drag-altered flowfields demonstrate that the dominant organization present upstream is significantly weakened or lost due …
-
Wake Filling Techniques for Reducing Rotor-Stator Interaction Noise
… for reducing the momentum deficit in a rotor wake and thus attenuate rotor-stator interaction noise. A secondary concern of the project was to reduce the amount of blowing required air for wake filling and thus limit the efficiency penalty in an aircraft engine environment. Testing was …
-
An experimental investigation of large-scale structures in supersonic reattaching shear flows
… the shear layers, at reattachment, and in the wake region of a supersonic base flow. Single-pulse side and end views were obtained at several streamwise locations to characterize the evolution and three-dimensionality of the large-scale motions. From statistically significant ensembles, spatial …
-
Complex Equilibrium of Laterally Curved Wakes
Turbulent wakes generated from an aircraft or submarine vehicles has been of main interest to researchers due to the broad band noise associated with such wakes. One such case is the noise generated by spiral vortices shed of from one blade interacting with another oncoming blade of helicopter …
-
Dynamics and stability of flow past a circular cylinder in ground effect
… DES. The linear stability analysis of analytical wake profiles then provides a possible explanation for the above experimental and computational results; that is, the cessation of the von Karman-type vortex shedding in ground effect may also be largely explained by the change of inviscid …
-
An experimental investigation of the two-stream, supersonic, near wake flowfield behind a finite-thickness base
The interaction region generated by separation of two supersonic streams past a finite-thickness base occurs in high-speed flight and characterizes the aft-end flowfield of powered missiles in supersonic flight. In order to examine fundamental mechanisms and interactions ongoing in this near-wake …
-
Development and Testing of the Virginia Tech Doppler Global Velocimeter (DGV)
… complex three-dimensional separated flow regions. The systems was designed for robustness, ease of use, and for acquisition of low uncertainty velocity data. A series of tests in the Stability Tunnel were conducted to determine the how well the new DGV system met these goals. Extensive …
-
Interactions among flow, sediment deposition and aquatic vegetation in a channel
… due to the velocity difference between the open region and the vegetated region. Coherent vortices are formed via Kelvin-Helmholtz stability in the shear layer, which also induces an edge wave. Both the energetic vortices and the edge wave enhance the lateral mass transport. Particles were …
-
Experimental and numerical investigation of second-generation, controlled-diffusion, compressor blades in cascade.
… on the suction side of the blades, and in the wake region. A numerical investigation was conducted using the rotor viscous code 3-D developed by Dr. Roderick Chima of NASA Lewis Research Center. Overall, good agreement between flow visualization, blade pressure measurements, laser measurements, …
-
Stability and Vortex Shedding of Bluff Body Arrays
… performed on selected velocity profiles in the wake region. The results of this analysis were used to guide the interpretation of the two dimensional results and formulate a general theory of stability of inline and staggered bluff body arrays. The nature of the flow in the unsteady regime …
-
Flow through and around fish farming nets
… velocity reduction inside the cage and in the wake region. The modeled drag force was higher than the measured drag force. The modeled current compared well with the measured current inside the cage, but the reduction was underpredicted in the wake of the cage.</p><p>Full scale simulations were …
-
Stereoscopic PIV measurements and proper orthogonal decomposition of a supersonic axisymmetric base flow
… several realistic applications, such as the wake region behind projectiles, bullets and unpowered rockets. A blowdown-type supersonic wind tunnel built specifically for axisymmetric base flows, located at the University of Illinois at Urbana-Champaign, is used to investigate these base flows. …
-
Investigation of the effect of a circular patch of vegetation on turbulence generation and sediment deposition using four case studies
… distribution of sediment deposition in the wake of a circular patch of model vegetation and the effect of the patch on turbulence and mean flow. Two difference types pf vegetation were used along with two different stem densities totaling four different case studies. The spatial location of …
-
Investigation of the effect of a circular patch of vegetation on turbulence generation and sediment deposition using four case studies
… distribution of sediment deposition in the wake of a circular patch of model vegetation and the effect of the patch on turbulence and mean flow. Two difference types pf vegetation were used along with two different stem densities totaling four different case studies. The spatial location of …
-
Time-Resolved PIV Measurements of Ship Airwakes with Quartering Winds
<p>The unsteady, three-dimensional, turbulent airwake over the Simple Frigate Ship No. 2 (SFS2) with quartering wind flow directions was studied in a low-speed wind tunnel facility. Surface oil flow visualization and time-resolved stereoscopic and planar particle image velocimetry (PIV) …
-
Modeling Ganymede's Interaction with the Jovian Magnetosphere: Ionospheric Outflow and the Juno PJ34 Flyby
… and large (O2+) masses in Ganymede’s interaction region. The results are validated by comparing the modeled magnetic field and ion densities against time series from Juno’s magnetometer and plasma instruments. The major findings are: (a) Ganymede’s internal dipole dominated the magnetic field …
-
Design and Analysis of a Deterministic Disturbance Generator
… until its dwell position, generating a large wake region due to airfoil stall after its peak. Comparison of data from the Goodwin Hall Subsonic Tunnel (GHST) with VTSWT data for overlapping domains revealed similar flow field features when normalized based on the boundary layer velocity (43mm …
Page 1 of 3