Date of Award

Spring 1985

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

Surendra N. Tiwari

Committee Member

Oktay Baysal

Committee Member

Charlie H. Cooke

Committee Member

John M. Kuhlman

Committee Member

Robert L. Ash

Abstract

The unsteady transonic small disturbance equation for an oscillating slender body is obtained from the full potential equation in cylindrical coordinates by means of a perturbation analysis. The time-dependent body-boundary condition is reduced into a simpler form by matching the outer and inner flows. Also, a time-dependent pressure coefficient over the slender body is derived by means of a matching principle. The simplified form of the body-boundary condition is incorporated into the difference equations at the body axis. This application allows use of the cylindrical coordinate system for the problem. By prescribing several different body-boundary conditions, various modes of body motion relative to the freestream velocity can be obtained. For the case of axial oscillatory motion, a modified form of the alternating direction implicit technique is applied in order to solve the resulting equations.

Calculations of the time-dependent surface pressure distributions and embedded subsonic or supersonic regions are performed for different Mach numbers in the transonic range while keeping certain physical parameters of the flow (such as thickness ratio, oscillation amplitude and reduced frequency) constant. Since no transonic unsteady surface pressure and embedded subsonic or supersonic region measurements are reported in the literature, results are compared only with the related steady-state surface pressures and embedded subsonic or supersonic regions. A periodic fluctuation pattern of the surface pressures and embedded subsonic or supersonic regions is observed in sequentially computed results as would be expected from a time marching oscillatory problem.

DOI

10.25777/y5r6-5f84

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