基于散射矩阵法的飞机壁板声学优化设计

采用散射矩阵法分析夹层板结构声学特性,并对典型的夹层板结构即飞机壁板进行声学优化,预计飞机壁板隔声特性,获得蒙皮、隔声隔热层、内饰板及它们的组合结构的声学性能。针对尾吊飞机客舱后部噪声过大问题,通过增加铺设隔热隔声层以及部分区域优化安装阻尼层等一系列被动降噪处理方法,对主要传递路径的飞机壁板结构进行优化,降低客舱后部噪声水平,并进行试验验证。试验结果表明:散射矩阵法可快速准确获得夹层结构的隔声性能,并与混响室法测试结果吻合较好;在厚度不变的前提下,改变隔热隔声层的铺设方式和材料密度对壁板隔声性能影响较小,但在蒙皮内侧粘贴阻尼层能在一定频段范围提高壁板隔声性能;将优化的壁板构型应用到飞机后舱段侧壁板,舱内噪声水平可降低约3 dB。

Acoustic optimization design of aircraft panel based on scattering-matrix method

A scattering-matrix method is applied to analyze the acoustic characteristic of a sandwich structure, and to optimize the insulation performance of a typical sandwich panel such as an aircraft panel. This method can calculate the transmission loss of the panel structures, and effectively and rapidly evaluate the acoustic insulation of the multilayered structure combined by skin panels, blankets and trim panels. Due to the fact that the sound pressure level at the rear of a commercial aircraft with tail suspension engines overtops the passenger cabin acoustical comfort requirement according to the noise frequency spectrum analysis, a series of noise treatments would be considered to the panels which are the main transfer path of external noise into the cabin. Meanwhile, an optimization has been applied to the aircraft panels and validated by flight test. The results show that (1) the scattering-matrix method can rapidly calculate the insulation performance of the sandwich panel, and has a good agreement to the test results of the reverberation room measurement methods; (2) the transmission loss of the aircraft panel would be little improved by changing the blanket layout and density under the condition that the thickness remains constant, but it could be obviously increased in some frequency range by adhering damping layer to the skin; (3) the cabin noise level would be reduced about 3dB when the optimal panel configuration is applied to the aircraft.