On the reduction of the flow-induced noise and its mechanism using porous materials with low acoustic transmission loss

(Investigation of the velocity and pressure near porous materials)

Abstract

In this study, we investigated the noise reduction mechanism for flow-induced noise of a rectangular cylinder using a porous material mainly focused on the velocity and pressure measurement results around the cylinder. Simultaneous measurements of the streamwise velocity and wall pressure fluctuations were performed. Further, POD analysis of the wake of the cylinder was also performed to investigate vortex structures. Results showed that the cross correlations of the streamwise velocity and wall pressure fluctuations were decreased when porous materials were used. In addition, dominant modes of streamwise and cross-streamwise velocity fluctuation in the wake of the cylinder showed that the time and space scale of vortices become smaller when porous materials were used. Therefore, it can be concluded these changes caused the decrease of the flow-induced noise of the cylinder.