Microphone array measurements on high-speed trains in wind tunnels

Abstract

The present study evaluates the capabilities of the phased microphone array technique for the localisation and quantification of aeroacoustic sound sources of high speed trains in wind tunnels. The major challenge is to obtain a sufficient resolution of the sources with low source strength. The experiments were carried out using 1:25 models in the Aeroacoustic Wind Tunnel Brunswick (AWB) of the German Aerospace Center (DLR). This Göttingen – type wind tunnel has an open test section which is surrounded by an anechoic chamber. The microphone array consists of 143 microphones and is positioned outside the flow. In order to achieve reasonable results a shear layer correction is applied. Performing a phase-calibration can increase the signal-to-noise ratio, especially for higher frequencies. This procedure will be presented als well.