Sakamoto Shuichi, Shin Juung, Abe Shota, Toda Kentaro
Department of Engineering, Niigata University, Ikarashi 2-no-cho 8050, Nishi-ku, Niigata 950-2181, Japan.
Graduate School of Science and Technology, Niigata University, Ikarashi 2-no-cho 8050, Nishi-ku, Niigata 950-2181, Japan.
Materials (Basel). 2022 Jul 24;15(15):5140. doi: 10.3390/ma15155140.
Zero-mass metamaterials comprise an orifice and a thin film. The resonance between the film and the air mass of the orifice hole is caused by sound waves, which significantly decreases the transmission loss at a specific frequency. The study novelly incorporates acoustic metamaterials in the delay tube of an interference silencer. In this case, it is determined that an interference silencer and a "side-branch silencer with two different branch pipe lengths" can be realized in a single silencer. At certain frequencies, the acoustic mass of the acoustic metamaterial approaches zero, which results in an interference silencer with the full length of the delay tube applied. At other frequencies, the acoustic metamaterial acts as a rigid wall with high transmission loss, thereby reflecting sound waves at the zero-mass metamaterial location. In this case, it is a side-branch silencer with two different tube lengths, corresponding to the tube lengths from the entrance and exit of the delay tube to the zero-mass metamaterial, respectively. The incorporation of zero-mass metamaterial into an interference-type silencer can introduce the silencing effect of a side-branch silencer with two different branch tube lengths without increasing the volume of the interference-type silencer. Theoretical values were obtained using the transfer matrix. Consequently, the theoretical and experimental values were close, enabling us to predict the transmission loss of the proposed silencer.
零质量超材料由一个孔口和一层薄膜组成。薄膜与孔口气团之间的共振是由声波引起的，这在特定频率下显著降低了传输损耗。该研究创新性地将声学超材料应用于干涉消声器的延迟管中。在这种情况下，可以在单个消声器中实现干涉消声器和“具有两种不同支管长度的侧支消声器”。在某些频率下，声学超材料的声学质量接近零，这导致应用延迟管全长的干涉消声器。在其他频率下，声学超材料充当具有高传输损耗的刚性壁，从而在零质量超材料位置反射声波。在这种情况下，它是一个具有两种不同管长的侧支消声器，分别对应于从延迟管入口和出口到零质量超材料的管长。将零质量超材料纳入干涉型消声器可以在不增加干涉型消声器体积的情况下引入具有两种不同支管长度的侧支消声器的消声效果。使用传递矩阵获得了理论值。因此，理论值和实验值接近，使我们能够预测所提出消声器的传输损耗。
