Date of Award

Spring 2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Aerospace Engineering

Committee Director

Colin P. Britcher

Committee Member

Drew Landman

Committee Member

William Humphreys

Call Number for Print

Special Collections; LD4331.E535 W55 2007

Abstract

Automobile aeroacoustics is still in its beginning stages. Understanding where control of the noise sources is addressed using mainly exploratory experimental methods and idealized models. The difficulty of reducing noise levels lies in the mechanisms that generate noise. Sound sources are generated from unsteady aerodynamics which arises from turbulent boundary layers and from regions of separated flow over the vehicle. These regions are subjected to unsteady pressures which are interpreted by the driver as undesirable noise. In order to reduce the noise around an automobile, the individual sources are best identified by . performing full-scale wind tunnel testing. This identification can be achieved by deploying a microphone phased array in a suitably configured wind tunnel test section. A microphone phased array permits discrimination of low-level sources in the presence of diffuse background noise by means of strong spatial variations in array sensitivity. The aim of this study is to demonstrate the technology available at NASA Langley Research Center 14 by 22 wind tunnel for microphone phased arrays for source localization in order to permit suppression of undesirable noises by design changes and improve the acoustic measurement capability for automobile testing.

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In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

DOI

10.25777/1yna-gx74

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