Simultaneous Multiplane PIV and Microphone Array Measurements on a Rod-Airfoil Configuration

Abstract

The aeroacoustic sound generation process on a rod-airfoil configuration has been investigated by means of simultaneous particle image velocimetry in the near field and phased-microphone-array measurements in the far field. Up to 20,000 particle image velocimetry snapshots per field of view have been recorded. A coplanar multiplane particle image velocimetry system has been used, providing statistically independent samples of the temporal derivative of the velocity field. Both measurements were conducted in a synchronized manner so as to enable the calculation of the cross-correlation between the acoustic pressure and flow quantities derived from the measured velocity fluctuations. The main idea of the concept used in the study presented here was to use the coefficient matrix obtained from the aforementioned correlation to identify regularities in the near-field fluctuations that are related to the radiated sound field. Additionally, a technique to localize flow structures responsible for the far-field sound by means of the calculation of the near-field intensity has been tested.