Insights Into The Acoustic Near And Far Field Based On Synchronized PIV And Microphone Measurements

The aim of this study is to detect and visualize the propagating sound waves emanating from a flow around different types of rods. For this purpose, synchronous Particle Image Velocimetry (PIV) and microphone measurements were performed in an aeroacoustic wind tunnel. The velocity fluctuations were recorded not only in the vicinity of the rods but also in several regions between the wake flow field and the far field microphone. By means of the correlation between velocity and pressure fluctuations, coherent structures within and outside the flow could be identified. In particular, the temporal and spatial development of these structures provides an insight into the sound generation mechanism and the transition between the acoustic near and far field. The results are compared with analytical and numerical solutions