IFAR Benchmark Challenge #4

Kurzfassung

This paper presents the contribution of the German Aerospace Center (DLR) to the fourth installment of the liner benchmark challenge under the framework of the International Forum for Aviation Research (IFAR). The challenge is devoted to exploring the effects of high sound pressure amplitudes on the impedance of liners. Therefore, four liner samples of varying geometric properties are produced by additive manufacturing based on the design data provided by NASA coordinating this benchmark. These samples are acoustically characterized in the normal incidence tube D-NIT at DLR Berlin as well as in the liner test facilities of the other participants. The effects of three different types of sources are studied: Tonal, multi-tone and broadband excitation. As all participants follow the same measurement program and study the same specimen, the results allow a comparative analysis of the effects of high sound pressure amplitudes on the impedance of liners as well as the underlying experimental and analysis methods.