Accession Number : ADA186464

Title :   Three-Dimensional Unsteady Flow Elicited by Finite Wings and Complex Configurations.

Descriptive Note : Doctoral thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s) : Ashworth, Jeffrey C

PDF Url : ADA186464

Report Date : Jan 1987

Pagination or Media Count : 188

Abstract : Studies of 2-dimensional unsteady separated flows have demonstrated possible aerodynamic benefits of controlled unsteady flows about airfoil surfaces. However, since all applicable wings are necessarily finite, a thorough understanding of 3-dimensional unsteady flows is essential. Any direct application or modelling of this complex 3-dimensional phenomenon may be somewhat premature until a characteristic data base is established. The spatial and temporal transport, accumulation and dissipation of vorticity on the surface of three wings varying only in sweep angles (forward, straight and aft) were examined using flow visualization and hot wire anemometry. Identical geometric positions were tested on each wing for a variety of dynamic parameters. Each sweep geometry produced distinct, time-dependent, spanwise and chordwise sites for vorticity accumulation into large scale leading edge and wingtip vortices. The wingtip and leading edge vortex interactions produced spanwise flow patterns uncharacteristic of 2-dimensional flows. Wing sweep is a dominant geometric parameter in analyzing the effects of unsteady wingtip flow. An initial investigation into the feasibility of unsteady flow application was performed on a model of the X-29 Forward Swept Wing Technology Demonstrator. This model geometry produces complex flow patterns but may be ideally suited for application of unsteady flow technology. Unsteady flow structures were observed which may ultimately generate beneficial, slow speed flight characteristics of advanced aircraft. These investigations provide initial insight into 3-dimensional flow behavior elicited by different sweep geometries and dynamic parameters. (Theses)

Descriptors :   *SWEPT WINGS, *THREE DIMENSIONAL FLOW, *UNSTEADY FLOW, *VORTICES, ACCUMULATION, AERODYNAMIC CONFIGURATIONS, AIRCRAFT, AIRFOILS, BENEFITS, CONTROL, DATA BASES, DYNAMICS, FLIGHT SPEEDS, FLOW VISUALIZATION, GEOMETRY, HOT WIRE, INTERACTIONS, LEADING EDGES, LOW VELOCITY, MODELS, PATTERNS, SURFACES, WING TIPS, WINGS, SWEPTFORWARD WINGS, DISSIPATION, FLOW SEPARATION, THESES

Subject Categories : Aerodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE