波纹穿孔板吸声特性研究

研究了平面波垂直入射和掠入射两种情况下波纹穿孔板对声波的耗散作用, 结果表明在这两种情况下波纹穿孔板的声学特性都有别于平板穿孔板。在垂直入射条件下, 通过“等效穿孔率”可以在中、低频率范围内使波纹穿孔板和平板穿孔板的吸声特性“重合”。波纹穿孔板在高频范围会出现异于平板穿孔板的双尖峰现象, 进一步研究发现这是由波纹板形状导致的背腔深度的连续变化所引起的。在掠入射条件下, 波纹穿孔板与平板穿孔板无法通过“等效穿孔率”替代。波纹穿孔板的板高和板长对其声学性能都有明显影响, 当波纹穿孔板夹角(板高与1/4板长对应的正切角)相同时, 在板长小于75 mm范围内波纹穿孔板有相似的声学性能。

Prediction and control of combustion instabilities in real engines

The dissipative effect of corrugated perforated plate on acoustic wave is studied in two cases of plane wave vertical incidence and grazing incidence in this paper. The results show that the acoustic performance of the corrugated perforated plate in both cases is different from that of the flat perforated plate. Under the condition of vertical incidence, the equivalent perforation rate can make the sound absorption coefficients of the corrugated perforated plate and the flat perforated plate coincide in the range of medium and low frequencies, but the corrugated perforated plate will have a double peak phenomenon that is different from the flat perforated plate at high frequencies. Further study reveals that it is due to the continuous change of the depth of the back cavity caused by the shape of the corrugated plate. Under the condition of grazing incidence, the corrugated perforated plate and flat perforated plate cannot be replaced by the equivalent perforation rate. The height and length of the corrugated perforated plate have obvious effects on its acoustic performance. When the angle of the corrugated plate is constant (the tangent angle corresponding to the plate height and a quarter of the plate length), the corrugated perforated plate with the plate length less than 75 mm has similar acoustic performance.