Investigating the Aeroacoustic Properties of Porous Fabrics

Abstract

The aeroacoustic properties of porous fabrics are investigated experimentally with the goal of finding a fabric that serves as an improved interface between wind tunnel flow and quiescent conditions. A total number of eight porous fabrics were investigated, namely, four glass fiber fabrics, two plain-weave Kevlar fabrics, and two modified plain Kevlar fabrics with their pores irregularly clogged. Two custom-made rigs were used to quantify the transmission loss (TL) and self-noise of all fabrics. The pores were found to serve as a low-resistance gateway for sound to pass through, hence enabling a low TL. The TL was found to increase with decreasing open area ratio (OAR), whereas other fabric properties had a minor impact on TL. The thread density was found to be a primary factor in determining the frequency range of porous fabrics’ self-noise, with the OAR potentially playing a secondary role in the self-noise levels. Fabrics with irregular pore distribution showed a more broadband self-noise signature associated with lower frequencies compared to fabrics with periodic pore patterns. Overall, fabrics with an irregular pore distribution or fabrics with increased thread density were identified as two potential ways to obtain superior aeroacoustic behavior compared to commonly used Kevlar fabrics.