Investigation of Aeroacoustic Noise Sources by Simultaneous PIV and Microphone Measurement

Abstract

Aeroacoustic noise is been generated by the flow around moving vehicles. Such noise sources are located for example near the rear mirror of a car or near by the high lift system of an approaching aircraft. Its reduction is therefore one important goal of the transport industry to accommodate for the growing demand for mobility. To develop noise reduction strategies it is necessary to detect noise sources and to understand noise generation mechanisms. The objective of the present study is the detection and understanding of noise generation mechanisms by cross correlation techniques. The basic idea behind this concept is to simultaneously measure the flow field and the radiated sound. This gives information which flow structures correspond with the recorded sound. A simple test case is chosen to verify this approach. Hence, the flow field around a circular cylinder is been investigated by Particle Image Velocimitry (PIV) while the radiated sound is recorded with a single microphone. Both measurements are conducted in a synchronized manner to enable the calculation of the cross correlation between flow field data and acoustic data. The developed methods are then applied to a more relevant problem. Therefore measurements on a high lift system of a generic aircraft half model are conducted. In particular the flow field inside a leading edge slat cove is investigated by PIV and the radiated sound is recorded by a single microphone.