Date of Award

3-2000

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Jeffrey Bons, PhD

Abstract

A computational study was conducted on the use of aft-mounted fairings for passive drag reduction on a sphere at Re=866,000. The sphere dimensions and operating Reynolds number were selected to approximate the flow around a proposed aircraft laser turret for which experimental data was available. To establish the validity of the computational model, flow predictions were compared to sphere data available in the open literature. The model, exercised in both the laminar and turbulent modes, showed good agreement with the published data. Two proposed laser turret fairings were then evaluated computationally: a large fairing (beginning at 49.5 degrees past the sphere apex) and a small fairing (beginning at 58.95 degrees past the sphere apex). Existing wind tunnel models were used to generate axisymmetric computational grids that approximated the geometry of these models. The computed flow field and associated drag reduction were comparable to the experimental results obtained from the wind tunnel testing. Differences in drag from the model to the experiment were explained by the axisymmetric simplifications made in the model. Finally, a new, optimized fairing model was designed which eliminated the separation zone on the aft portion of the sphere. The optimized model predicted double the drag reduction compared to the large fairing computational model.

AFIT Designator

AFIT-GAE-ENY-00M-11

DTIC Accession Number

ADA380295

Comments

The author's Vita page is omitted.

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