Degree Type

Dissertation

Date of Award

1993

Degree Name

Doctor of Philosophy

Department

Aerospace Engineering

First Advisor

Anna Pate

Second Advisor

J. Adin Mann, III

Abstract

The objective of this research is to investigate sound scattering by an object using a two-surface measurement technique that separates the incident field and the scattered field. The separation technique is developed in cartesian and cylindrical coordinates. The decomposition method in the cartesian coordinate system is based on the principle that any wave form can be decomposed into plane-wave components by using a two dimensional spatial Fourier transform. For the cylindrical coordinate system, a two plane separation technique is based on decomposing the sound field into cylindrical waves. Numerical simulations are performed and the effect of various parameters are investigated. Specifically, the distance between two measurement surfaces, the distance between measurement points, and the aperture size are investigated. In addition, experimental studies were conducted inside an anechoic chamber with a baffled loudspeaker as a source, illuminating four different scatterers. The decomposed scattered field is then used to estimate the far-field target strength. The experiments demonstrate the feasibility of the field separation technique.

DOI

https://doi.org/10.31274/rtd-180813-10024

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Ming-Te Cheng

Language

en

Proquest ID

AAI9413962

File Format

application/pdf

File Size

182 pages

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