关键词: 穿孔板, 声阻抗, 声学阻抗管, 声学流管, 传递损失

Abstract: Based on the impedance tube and flow tube test platforms, the acoustic impedance characteristics of large thickness perforated plates suitable for over-the-rotor liner and soft vans are experimentally investigated in the absence and pres-ence of grazing flow, and the applicability of the Beihang model to the prediction of acoustic impedance for large thick-ness perforated plates is explored. Under the no grazing flow condition, the test acoustic impedance of a solid perforated plate with a thickness of 8 mm shows good linear characteristics, and the Beihang model is able to accurately predict the acoustic impedance of the large thickness perforated plate. Meanwhile, a honeycomb-cavity sandwich perforated plate structure is proposed for the case where the static blade is a hollow structure. Measurement results show that the acous-tic impedance of this structure is mainly provided by the perforated plates on both sides, and the honeycomb cavity in the middle provides only a small portion of the acoustic impedance. In the presence of grazing flow conditions, the applicabil-ity of the Beihang model to the prediction of acoustic impedance for large-thickness perforated plates is investigated in terms of both acoustic impedance prediction accuracy and transmission loss. When the grazing flow velocity is 10m/s and 20m/s, the Beihang model is still able to accurately predict the acoustic impedance of large thickness perforated plates. As the grazing flow velocity increases, the effect of plate thickness on vortex shedding in small holes begins to become apparent. When the grazing flow velocity is 40m/s and 60m/s, the prediction error of the Beihang model based on the fitting of vortex shedding strength of the thin plate on the acoustic impedance of the large thickness perforated plate starts to become larger. However, in terms of the transmission loss, the transmission loss curve of acoustic impedance predicted by the Beihang model shows a similar trend with that of the experimentally measured transmission loss curve. It can be seen that the Beihang model still has a certain guiding effect on the engineering application of large thickness perforated plates.

Key words: perforated plate, acoustic impedance, acoustic impedance tube, acoustic flow tube, transmission loss