Date of Award

Spring 1993

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

Surendra N. Tiwari

Committee Member

Robert E. Smith

Committee Member

Arthur C. Taylor, III

Committee Member

John J. Swetits

Committee Member

Gene Hou

Abstract

An algorithm is developed to obtain the grid sensitivity with respect to design parameters for aerodynamic optimization. Two distinct parameterization procedures are developed for investigating the grid sensitivity with respect to design parameters of a wing-section as an example. The first procedure is based on traditional (physical) relations defining NACA four-digit wing-sections. The second is advocating a novel (geometrical) parameterization using spline functions such as NURBS (Non-Uniform Rational B-Splines) for defining the wing-section geometry. An inter-active algebraic grid generation technique, known as Two-Boundary Grid Generation (TBGG) is employed to generate C-type grids around wing-sections. The grid sensitivity of the domain with respect to design and grid parameters has been obtained by direct differentiation of the grid equations. A hybrid approach is proposed for more geometrically complex configurations. A comparison of the sensitivity coefficients with those obtained using a finite-difference approach is made to verify the feasibility of the approach. The aerodynamic sensitivity coefficients are obtained using the compressible two-dimensional thin-layer Navier-Stokes equations. An optimization package has been introduced into the algorithm in order to optimize the wing-section surface using both physical and geometric parameterization. Results demonstrate a substantially improved design, particularly in the geometric parameterization case.

DOI

10.25777/mqp6-9r54

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