Prediction of Airflow Resistivity of Fibrous Acoustical Materials having Double Fiber Components and a Distribution of Fiber Radii

Presented here is a new airflow resistivity (AFR) prediction model that accounts for situations in which a fibrous medium comprises more than one fiber component, and when the radius of each fiber component varies within a certain range. The study started with the evaluation of existing AFR models, which were mostly developed for single component fibers with uniform radius (SCUR). After comparing the SCUR predictions results with AFR measurements of different single component fiber samples, the models with reasonable prediction accuracy, such as those due to Tarnow, Doutres, and Horoshenkov were chosen as starting points. Those models were first modified to make them capable of predicting AFR for double component fibrous media with uniform radii (DCUR). They were then further modified by adding the effect of fiber radius distributions to the DCUR models and making them capable of predicting AFR for double components fiber with various radii (DCVR). After adjusting the distribution parameters of both components, the DCVR models prediction results were verified by comparison with AFR measurements on different double components fiber samples. It was also found that the DCVR model prediction results were affected by the implicit differences in their starting points: i.e., the assumption as to whether the material consisted of pores (e.g., Doutres and Horoshenkov) or fibers (e.g., Tarnow). The effects and potential reasons for these differences are discussed along with aspects of the models that can be studied in the future.