Measurements of the Effects of Streamwise Riblets on the Turbulence Structures in Boundary Layers

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Creator: 

Ancrum, Derek

Date: 

2016

Abstract: 

This study presents experimental results on the effects of streamwise-oriented riblets on the coherent structures of turbulence. The riblet spacings correspond to 0.5 and 1.5 times the natural spacing of the low-speed streaks. The cross-sectional dimensions of the riblets were chosen to promote more effective control on the development and spatial distribution of wave packets consisting of hairpin vortices. Of the two riblet spacings considered, the wider spacing demonstrated effective control on the spanwise positioning of the wave packets, enabling reduction in their mutual interaction and realizing a reduction in their spanwise density compared to the conditions on a smooth surface. The closer-spaced riblets were observed to have even more control on the spanwise positioning of the wave packets, and produced notably stronger sweep and ejection events while promoting mutual interaction of hairpin vortices in spanwise-adjacent wave packets via spanwise-oriented vortical structures created by a Kelvin-Helmholtz instability mechanism.

Subject: 

Engineering - Aerospace
Physics - Fluid and Plasma

Language: 

English

Publisher: 

Carleton University

Thesis Degree Name: 

Master of Applied Science: 
M.App.Sc.

Thesis Degree Level: 

Master's

Thesis Degree Discipline: 

Engineering, Aerospace

Parent Collection: 

Theses and Dissertations

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