Title page for ETD etd-08062007-094404
|Type of Document
||Hoang, Ngoc T.
||The hemisphere-cylinder at an angle of attack
|Telionis, Demetri P.
|Devenport, William J.
|Hendricks, Scott L.
|Jones, Gregory S.
|Morris, Don H.
|Ragab, Saad A.
- Wakes (Aerodynamics)
|Date of Defense
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
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