Broadband sound-absorption of perforated lining in the presence of grazing flow

For large aperture perforation plate,reducing acoustic mass is a way to realize broadband sound absorption.Meanwhile,the acoustic resistance can be enlarged due to the grazing flow effect as well as the reduction of the acoustic mass.Based on above results,the designing principle was proposed for the parameters of the perforation plate.Besides this,the perforated plate muffler experiment was also conducted.The experimental results show that broadband sound absorption can be achieved for large aperture perforation plate with low acoustic mass in the presence of grazing flow when compared with that of perforated lining without grazing flow.Such perforation plate can be applied to the noise reduction of the aircraft engine nacelle,inlet and exhaust pipe of motor engine,and all kinds of ventilation pipe with large air flow.