Date of Award

Fall 1994

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Engineering Mechanics

Committee Director

Osama A. Kandil

Committee Member

Robert L. Ash

Committee Member

Oktay Baysal

Committee Member

Colin P. Britcher

Committee Member

Chen-Huei Liu

Abstract

At high angles of attack, the flowfield over slender forebodies becomes asymmetric with substantial side force, which may exceed the available control capability. The unsteady compressible Navier-Stokes equations are used to investigate the effectiveness of different active control methods to alleviate and possibly eliminate the flow asymmetry and the subsequent side force. Although the research work focuses on active control methods, a passive control method has been investigated. The implicit, Roe flux-difference splitting, finite volume scheme is used for the numerical computations. Both locally-conical and three-dimensional solutions of the Navier-Stokes equations are obtained.

The asymmetric flow over five-degree semi-apex angle cone is used as a reference case to which the different control methods are applied and compared. For the passive control method, the side-strakes control is investigated. The parametric study includes the control effectiveness of the strake span length.

For the active control methods, flow injection in the normal and tangential directions to the body surface has been investigated. Both uniform and pressure-sensitive mass flow injection are applied, and the effects of mass flow rate, injection angle and injection length have also been studied. Injection, with a parabolic profile, is applied from the cone sides tangent to its surface. Surface-heating, where temperature of the cone surface is increased, is also investigated. The effectiveness of a hybrid method of flow control which combines injection with surface heating has been studied. The cone spinning and rotary oscillation around its axis are applied as an active control method. The computational applications include the effects of uniform spinning rates and periodic rotary oscillations at different amplitudes and frequencies on the flow asymmetry.

DOI

10.25777/ev9y-se58

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