An experimental anechoic research of perforated plates for nacelle liner has been completed under conditions of different rotor speeds and inlet Mach numbers.The duct

which was lined with single segment or three segments made of the perforate honeycomb plates or had a hard wall

was installated on a transonic axial compressor facility at BUAA.The experimental results discovered some anechoic features of the perforated plate honeycomb structure and enriched data base for designing the engine nacelles.A new nacelle liner

which has larger cavity-depth and open area ratio

has been designed. The largest noise reduction can reach to 10

5 dB under the condition that the acoustic treatment length is only 30 cm.