Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : July 10, 2017 - July 12, 2017
A perforated plate with a backing cavity is often used as an acoustic liner. In this study, we measured sound absorption coefficients, α, of the acoustic liners with grazing flow by use of a flow duct. The flow speed, U, in the duct was set around 0-44m/s, and the SPL was set up to 140dB. We proposed a propagation constant method (PCM) to calculate α. We employed another method, back microphone method (BMM), in which a microphone on the end of the backing cavity was installed. These obtained α values were compared with the α obtained by use of the standard impedance tube method (ITM). When U = 0, the α values by PCM agree with the values by ITM around the peak frequency, and the values by BMM agree well with the values by ITM in wide frequency range. When U ≠ 0 (ITM is inapplicable), the α values by PCM and the values by BMM agree around the peak frequency although the values by PCM are fragmentary.
