Date of Award

Summer 1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Aerospace Engineering

Committee Director

Osama A. Kandil

Committee Member

Colin P. Britcher

Committee Member

Brett A. Newman

Committee Member

Tin-Chee Wong

Abstract

The unsteady, three-dimensional Navier-Stokes equations are solved to simulate and study the aerodynamic response of a delta wing undergoing large amplitude pitching motion up to 90° angle of attack. The primary model under consideration consists of a 76° swept, sharp-edged delta wing of zero thickness, initially at zero angle of attack. The freestream Mach number and Reynolds number are 0.3 and 0.45 × 106, respectively. The governing equations are solved time-accurately using the implicit, upwind, Roe flux-difference splitting, finite-volume scheme. Both laminar and turbulent flow solutions are investigated. In the laminar flow solutions, validation of the computational results is carried out using existing experimental data, and shows good agreement.

The effect of reduced frequency of the wing motion is then presented and a grid refinement study is introduced. In the turbulent flow simulations, both Baldwin-Lomax and Spalart-Allmaras turbulence models are used and the results are compared with those of the laminar solution and experimental data as well. A sinusoidal pitching motion of the wing is also investigated in the present work. The computational results provide complete information and details about the flowfield response, which are difficult to obtain from experiment. A feasibility study of using one of the flow control techniques, blowing, to enhance maneuverability is introduced.

The investigation of the unsteady flow over a wide range of angles of attack provides crucial understanding of the variations of the leading edge vortex cores, their breakdown behavior, aerodynamic hysteresis, and wing aerodynamic characteristics at very high angle of attack. The current study shows that numerical simulations in the very high angle of attack range are obtainable. Such calculations were thought to be unattainable as recently as the 1980's.

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DOI

10.25777/ehmk-vc03

ISBN

9780599524989

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