IFAR Liner Benchmark Challenge #6: Effect of Liner Length on Impedance Eduction Using JAXA Flow Duct

This paper describes the contribution of Japan Aerospace Exploration Agency (JAXA) to the sixth of the liner benchmark challenges within the framework of the International Forum for Aviation Research (IFAR). The objective of this challenge is to investigate the effect of the axial length of the liner on the acoustic impedance educted using flow duct rigs. In this challenge, participants were assigned to use three types of liners with different geometries and characteristics. JAXA prepared three different axial lengths for each liner and conducted the tests under multiple flow velocities and incident sound pressure conditions. The test results were discussed mainly in terms of the accuracy of the impedance eduction and the effect of linearity of the liners. As the data obtained in this study will be shared among the participants, further discussion and improvement of techniques are expected through comparison of the data in the future.