Comparability of Microphone Array Measurements in Open and Closed Wind Tunnels

Abstract

The phased microphone array has become a widely used tool in aeroacoustic testing for the localization and quantification of sound sources. Measurements are often carried out in wind tunnels with open or closed test sections. The underlying thesis investigates the performance and comparability of microphone array measurements conducted in wind tunnels with open and closed test sections and carries out a systematic comparison. The various effects influencing the aeroacoustic results of testing in different wind tunnels can be summarized in three main groups. Deviations can result from influences which can affect the aeroacoustic sound generation. The second group concerns differences in the experimental setup. Finally, the third group consists of the varying test section boundary conditions and propagation effects. In the framework of the assessment of the comparability of microphone array measurements in open and closed wind tunnels, this thesis focuses on the third group - the influence of test section boundary conditions and propagation effects on microphone array results. Nonetheless, the first two points are also of concern and discussed in this thesis.