IFAR Liner Benchmark Challenge #7: Effect of Flow Profile on Impedance Eduction Using JAXA Flow Duct

Recently, it is furthermore crucial to design acoustic liners that efficiently reduce noise because the given installation area is limited on the nacelle in high bypass ratio turbofan engines. Therefore, advancing impedance eduction technology, investigating the effect of the glazing flow profile including boundary-layer on the educed impedance should be done in detail. In this study, to control the boundary-layer, the serration of duct wall is designed and introduced into the flow duct rig in Japan Aerospace eXploration Agency (JAXA). Next, three Single Degree Of Freedom (SDOF) liner specimens with different Percent Open Area (POA) are fabricated. Then, these specimens are installed in the rig and acoustic measurements are conducted under various glazing flow conditions. Finally, the impedance of the specimens is educed from experimental results and analyzed. This study is conducted within a research program of the international forum for aviation research (IFAR) challenges #6 and #7.