Experimental Evaluation Methods of Aeroacoustic Noise Based on Time Series Analysis of Flow Field

Abstract

In this study, we propose an experimental method for evaluating dipole sound on the basis of the vortex sound theory. By using time-resolved particle image velocimetry (PIV) in a wind tunnel test, we measured time series data of unsteady two-dimensional flow around a circular cylinder which is suitable for applying the vortex sound theory and validating our proposed methods. The sound pressure in the far field experimentally estimated from PIV measurements is validated by a correlation analysis with a measured sound pressure. Furthermore, we performed a correlation analysis between the source intensity defined as the integrand in the equation of the vortex sound theory and the measured sound pressure to determine the relationship between the estimated dipole sound and the measured flow field. The results show that the estimated sound pressure can detect the Aeolian tone due to Karman vortex shedding. Periodic fluctuation around the shear layer separation regions and the vortex formation region in the wake region causes the estimated dipole sound.