Date of Award

Summer 1982

Document Type

Thesis

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

J. M. Kuhlman

Committee Member

O. A. Kandil

Committee Member

C. S. Reddy

Call Number for Print

Special Collections; LD4331.E56S468

Abstract

Two different singularity methods have been utilized to calculate the potential flow past a three dimensional non-lifting body. Two separate FORTRAN computer programs have been developed to implement these theoretical models, which will in the future allow inclusion of the fuselage effect in a pair of existing subcritical wing design computer programs.

The first method uses higher order axial singularity distributions to model axisymmetric bodies of revolution in an either axial or inclined uniform potential flow. Use of inset of the singularity line away from the body for blunt noses, and cosine-type element distributions have been applied to obtain the optimal results. Excellent agreement, to five significant figures, with the exact solution pressure coefficient value has been found for a series of ellipsoids at different angles of attack. Solutions obtained for other axisymmetric bodies compare well with available experimental data.

The second method utilizes distributions of singularities on the body surface, in the form of a discrete vortex lattice. This program is capable of modeling arbitrary three dimensional non-lifting bodies. Much effort has been devoted to finding the optimal method of calculating the tangential velocity on the body surface, extending techniques previously developed by other workers. Again, the best solution for ellipsoids at angles of attack ranging between 0-30°, has been obtained using cosine spacing of the elements axially.

For a simple axisymmetric body of revolution without any slope discontinuity on the body surface, the first method offers a more accurate solution for less computational cost than the second method. Therefore, while the surface singularity method has the advantage of greater geometry generality, the axial singularity method is judged more suitable for modeling of fuselage effects in a preliminary aerodynamic design computer program.

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DOI

10.25777/66mv-ze19

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