Extended-reacting liners in time-domain simulations for broadband attenuation with flow

The modeling and optimization of acoustic liners under grazing flow is an on-going research topic with applications in the aerospace, automotive and railway industries. Recently, the push for next generation airliners and low-noise ventilation systems further increase the need for innovative configurations with improved broadband performance, and with limited size. Porous materials and metamaterials are good candidates to achieve these goals. In this work we propose a time-domain numerical modeling of extended reacting liners using an effective medium approach, which allows to characterize complex media such as porous materials and metamaterials through their effective density and compressibility. The linearized Euler equations are solved in the time domain using efficient high-order finite-difference schemes. The calculation of the convolution integrals is avoided through the auxiliary differential equation method. After a validation of the numerical methodology in a 1-D case, we will present the results for various 2-D configurations, with special attention to the impact of flow. A number of experiments in a Kundt’s tube and in a wind tunnel at the Ecole Centrale de Lyon are also under way to test the model predictions.