Date of Award

3-1999

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Paul I. King, PhD

Abstract

The Air Force Institute of Technology Boundary Layer Research Facility test section was modified to create controlled non-zero streamwise pressure gradients. The capability of the modified facility to reproduce theoretical laminar boundary layer velocity profiles and to create a self-preserving flow with an adverse streamwise pressure gradient was verified with three-dimensional laser Doppler anemometry. The effects of streamwise adverse and favorable pressure gradients on turbulent boundary layer flow characteristics (velocity profiles, turbulence and skin friction) and vortex formation over a flat plate with riblets at low speed (U = 5 mIs) were studied. Normal and spanwise velocity profiles for both pressure gradients showed the presence of paired counter-rotating vortices nested within the riblet valleys. These flow structures increased drag and significantly altered near-wall flow compared to a smooth plate turbulent boundary layer. The adverse pressure gradient tended to degrade these vortices as the flow progressed.

AFIT Designator

AFIT-GAE-ENY-99M-09

DTIC Accession Number

ADA361555

Comments

The author's Vita page is omitted.

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