Date of Award

12-1997

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Paul I. King, PhD

Abstract

This project investigated the flow field characteristics over a flat, ribletted plate and the effects of an adverse pressure gradient on this flow field. Testing examined the development of the flow over the ribletted plate from laminar through fully turbulent flow fields. The flow field states (laminar, transitional, and turbulent) were determined using local turbulence intensity values and boundary layer profiles. Several parameters were examined to help better describe the flow characteristics, boundary layer profiles, and influence on skin friction drag. The skin friction drag coefficients were calculated using a numerical integration technique to determine an average value and scaled to the platform area of the plate to compare results with smooth plate values. Although the geometry and flow conditions produced a drag augmenting case, skin friction followed trends described by the other flow parameters; streamwise velocity, Reynolds stress, etc. At locations where the boundary layer developed in the riblet valley, the skin friction was higher. As the flow developed to transitional and fully turbulent, higher values were also experienced. For the zero pressure gradient and mild adverse pressure gradient, counter rotating vortices developed in the riblet valley. This more organized motion also had slightly reduced skin friction below the transitional flow field for the plate as well.

AFIT Designator

AFIT-GAE-ENY-97D-01

DTIC Accession Number

ADA336654

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