Feng-Tai Hwang

Master of Science, May 1996

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ABSTRACT

To have a quiet compartment for passengers, noise source elimination and noise level reduction are very important to the automotive industry. To accomplish these, one must first understand how these sounds are generated. There are two fundamental mechanisms for sound generation:

1. Stucture-borne sound: Vibration of solid bodies resulting in the generation and radiation of sound energy.

2. Aerodynamic sound: Flow induced noise resulting from pressure fluctuations, and by turbulence and unsteady flows.

This work is focused on aerodynamic sound which results from the radio antenna. Strumolo [1] obtained a good mathematical model that describes how sound is generated by an antenna. In the model, the antenna is represented by a cylinder. A simple formula for sound intensity was derived based on far field assumptions. The motivation of the present study is to modify the mathematical model of Strumolo [1] in an attempt to improve the prediction of the sound pressure level in the near field.

Research supported by the Minnesota Center for Industrial Mathematics (MCIM)