Session: 01-02-01: Passive, Semi-Active, and Active Noise and Vibration Control

Paper Number: 111199

111199 - A Composite Structure for Low-Frequency Sound Absorption With Continuous Broadband Under High Sound Pressure Excitations 

High-amplitude sound absorption in the low-frequency range is of great interest because of its vast engineering applications. This work is associated with a novel composite multilayer structure for high-amplitude sound energy attenuation. An analytical model based on the equivalent fluid method by using JCAL (Johnson - Champoux - Allard - Lafarge) model is established to predict the sound absorption performance of the multilayer structure both under 90 dB excitation and 140 dB excitation. Numerical simulation is applied to verify the accuracy of the analytical model. This work demonstrates four samples with different parameters to compare the analytical and numerical results. The resonance frequencies of all samples locate in the low-frequency range. It is also found that the resistance of the multilayer structure is enlarged as the sound excitation increases, which can be utilized to design high-intensity sound energy absorbers. The numerical method can also be used to describe the flow field of the multilayer structure. From the velocity distributions, in the linear sound regime, the velocity of air is slow, and the energy dissipation is from the friction between the airflow and the boundary walls. In the nonlinear sound regime, the velocity is intense, resulting in the generation of vortices. The vortices are shed from the main pore and slits obviously, which can transfer the sound energy into kinetic energy and convert it into heat further, revealing a different energy dissipation mechanism under high amplitude sound excitations. The effects of geometrical parameters of the multilayer structure on the sound absorption performance are also studied in this work. It is found that the main pore has the greatest influence on the sound absorption performance of the multilayer structure. The absorption performance of the designed structure, including the sound absorption coefficient and the bandwidth, is improved under high sound pressure excitations. To further broaden the sound absorption bandwidth in the low-frequency range, a composite multilayer structure with three absorption units is designed to continuously achieve high-efficiency sound absorption. The composite structures combine the sound absorption performance of each unit. Experiments on sound absorption coefficients are tested by utilizing an impedance tube under different sound excitations. The experimental sound absorption coefficients agree well with both the analytical and numerical results. The results show that the designed composite multilayer structure has a superior noise reduction capability with continuous bandwidth under a high sound pressure environment in the low-frequency range.

Keywords: High-amplitude sound excitation; Sound absorption coefficient; Composite structures; Sound energy dissipation.

Presenting Author: Junzhe Zhu Shanghai Jiao Tong University

Presenting Author Biography: Junzhe Zhu is currently pursuing the Ph.D. degree in Mechanical Engineering at Shanghai Jiao Tong University. His current research interests include noise control, acoustic metamaterials.

Authors:

Junzhe Zhu Shanghai Jiao Tong University
Hao Gao Shanghai Jiao Tong University
Yegao Qu Shanghai Jiao Tong University
Guang Meng Shanghai Jiao Tong University