New experimental and theoretical methods to model perforated plate in the presence of grazing airflow

While perforated plates are commonly used in mufflers to attenuate exhaust noise, the relationship between their design parameters, such as hole size and percentage open area, and their acoustic performance, particularly at high sound pressure levels and strong airflow conditions, is not fully understood. This study presents an experimental method to investigate how airflow affects the transfer impedance of these plates. By testing different plate designs (5% to 40% open area) and airflow conditions (0.03 to 0.15 Mach), a new theoretical impedance model to predict their acoustic performance is proposed and tested by comparing the predicted transmission loss with existing models and measured values. The proposed model showed superior accuracy in predicting transmission loss across a wide range of plate designs (5% to 40% open area), demonstrating its potential effectiveness in optimizing muffler performance.