Date of Award

6-1998

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Milton E. Franke, PhD

Abstract

This study investigated the use of aft-mounted fairings and splitter plates to reduce the drag of a half-scale aircraft laser turret. Forces, moments, and pressure distributions were measured in the AFIT 1.5-m (5-ft) wind tunnel at Reynolds numbers between 3x10 to the 5th power and 9x10 to the 5th power based on the turret diameter. Oil traces indicated the nature of the flow near the surface of the unmodified turret and the surrounding area. Tufts placed on the turret, fairings, and splitter plates showed changes in separation regions when configurations were changed. The flow around the turret was characterized by dominant vortices shedding from the top of the turret and a large trailing wake of vorticity. Splitter plates were ineffective in reducing drag as a result of the strong flow over the top of the turret. A small fairing reduced baseline drag by 49% but was unable to produce attached flow near the turret. A large fairing eliminated nearly all separation regions and reduced baseline drag by 55%.

AFIT Designator

AFIT-GAE-ENY-98J-02

DTIC Accession Number

ADA346110

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