Local flowfield about large distributed roughness elements in a laminar boundary layer

The local flowfield about large roughness elements placed in a flat plate laminar boundary layer was studied. Flowfield measurements were taken upstream, over, and downstream of an isolated hemispherical roughness element and distributed hemispherical roughness elements. The height of the roughness elements was large compared to the local undisturbed boundary-layer thickness. The roughness flowfields were scaled such that the roughness Reynolds number, $Re\sb{k}$, and the ratio of the roughness height to boundary-layer thickness, $k$/δ, were typical of those found in initial glaze-ice accretions. For the isolated roughness case, $k$/δ = 2.5, and at the leading edge of the distributed roughness, $k$/δ = 3.4. The nominal value of $Re\sb{k}$ for both cases was 3700. The large physical size of the elements improved the spatial resolution of the measurements and helped facilitate the flow visualization. Velocity measurements were obtained with a 2-D laser Doppler velocimeter (LDV). Two-dimensional velocities, 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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Winkler, John Francis

Contributors dc:contributor

• Bragg, Michael B.

• Engineering, Aerospace
• Engineering, Mechanical

Statement dc:rights

• Copyright 1996 Winkler, John Francis

Language dc:language

eng

Identifier

9780591199659
AAI9712483
(UMI)AAI9712483

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21513