DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click HERE
to register or log in.
A Flow Visualization Study of Laminar/Turbulent Transition in a Curved Channel
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
Pagination or Media Count:
Laminarturbulent transition was studied as it occurs in a newly constructed curved channel of rectangular cross section. The channel is 1.27 centimeters high by 50.8 centimeters wide 0.5 in. x 20 in., aspect ratio of 40 to 1, with a concave surface radius of curvature of 60.96 centimeters 24 in.. Mean velocities for air in the channel range from 1.40 to 3.89 msec, which corresponds to Dean number and hydraulic Reynolds number ranges of 167 to 4651 and 2,231 to 6,173, respectively. Flow visualization from a smoke ire shows changes in the behavior and appearance of a smoke trace illuminated in the radial plane with varying Dean number and varying channel location. In some cases, these smoke trace patterns show distortion similar to what would be expected if pairs of counter-rotating vortices are present. A map of vortex stability as channel location and Dean number were varied was constructed from analysis of smoke trace photographs. Keywords Dean vortices Taylor Gortler vortices Dean number Rectangular curved channel Secondary flow Laminar flow Concave curvature Convex curvaturre.
APPROVED FOR PUBLIC RELEASE