Perforates are frequently used as part of sound reducing treatment in for instance aircraft engine and IC engine applications. In these applications they are exposed to fluid flow and high-level acoustic excitation, and this influences the acoustic properties of the perforate, as is well known from many published papers. The acoustic properties are usually described using a transfer impedance. In a previous part of this study the effect on the real part (resistance) of the transfer impedance was studied using both a conventional impedance tube (two-port) setup and an innovative three-port setup. The three-port configuration made it possible to study both the effect of grazing flow and high-level excitation effects separately as well as jointly. The present paper is a follow-up study where the imaginary part (reactance) of the transfer impedance is the focus. Comparisons are made with results from previously published papers and empirical models.
Part of ISBN 9788011034238
QC 20231010