Masters Thesis

Development of an Anechoic Wind Tunnel

Aircraft noise is a major concern and reducing its effects is a major topic of research. in order to study the concept of reducing its effects, a facility to create the required environment is developed. This study focuses on developing an anechoic wind tunnel facility at California State University, Fullerton. This study is conducted experimentally using low speed wind tunnel whose test section walls have been acoustically treated to simulate an acoustically free-field environment with forward flight. the side walls of the wind tunnel test section are fitted with anechoic chambers. Each wall of an anechoic chamber is lined with acoustical foam that has an absorption coefficient greater than 1.0. the two side walls of the test section are lined with tensioned Kevlar screens which act as interface between the test section and the anechoic chambers. a two-dimensional traverse is installed into the test section in order measure the turbulence intensity of the momentum wake with a hot-wire anemometer and determine its impact on sound attenuation. the objectives of this study is to quantify the level of noise attenuation in performance of the anechoic chambers, and quantify study the noise reduction by the momentum wake of an airfoil and identify the level of noise reduction from wake diffraction and dispersion. Preliminary results regarding the test section calibration with a white noise source are presented. the interaction of a noise source and the momentum wake of a NACA 0012 airfoil is investigated.


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