| Popis: |
This paper presents the contribution from the German Aerospace Center (DLR) to the first challenge of a liner benchmark under the framework of the International Forum for Aviation Research (IFAR). Therefore, two sets of acoustically damping wall treatment, called liner samples, have been produced by additive manufacturing based on the design data provided by NASA coordinating this benchmark. These liner samples have been integrated and acoustically characterized in the liner flow test facility DUCT-R at DLR Berlin. Besides the dissipation coefficients and the axial pressure profiles the liner wall impedance was educed by first determining the axial wave numbers and then applying a straightforward method based on the one-dimensional Convected Helmholtz Equation. |
