高声强下微穿孔板吸声结构的非线性效应抑制研究

Micro-perforated panel (MPP) absorber has good sound absorption properties under linear condition at low sound pressure levels, which has become an important mean to reduce noise in noise control field. But at high sound intensity, its application is greatly limited due to the nonlinear effect that not only decreases its absorption performance but also makes it hard to establish accurate impedance model. To solve this problem, this project intends to conduct study on the suppression of the nonlinear effect, through that the absorption performance of the micro-perforated panel will be improved, and at the same time, the needed acoustic characteristics can be realized according to its perfect linear theory. In this project, on the basis of the previous studies and the generation mechanism of the nonlinear effect, an effective method to suppress the nonlinear effect based on ultra-micro perforated panel is proposed. We plan to combine the methods of theoretical analyses, experiments and numerical simulations, a semi-empirical model of acoustic impedance is set up to discuss the influence rule of variations in the structure parameters on the nonlinear effect of single-layer ultra-micro perforated panel at high sound intensity. And then the suppression mechanism of nonlinearity effect based on single-layer ultra-micro perforated panel will be revealed. On the base, the composite ultra-micro perforated panel construction that can obtain the equivalent acoustic characteristics as single-layer ultra-micro perforated panel but is thinner will be presented and studied. The achievements of this project will provide a new idea for broadening the effective application of micro-perforated panel absorber at high sound pressure conditions.

微穿孔板吸声结构在低声压级线性条件下具有良好的吸声性能，已成为噪声控制领域一项重要的降噪手段，但在高声强下由于非线性效应，存在吸声性能下降以及难以建立精确的声阻抗理论模型的局限性。针对此问题，本项目拟通过开展高声强下微穿孔板结构的非线性效应抑制研究，达到既能改善其吸声性能，又能够应用其线性条件下完善的声阻抗理论模型对其吸声特性进行按需设计的目的。在课题组前期研究基础上，本项目从非线性效应的产生机理出发，提出基于超微孔微穿孔板（孔径d<100um）的非线性效应抑制方法，拟综合理论分析、实验与数值模拟，通过建立高声强下单层超微孔微穿孔板声阻抗的半经验模型，探讨结构参数变化对非线性效应的影响规律，并进一步揭示基于单层超微孔微穿孔板的非线性效应抑制机制，最后在此基础上提出并研究可实现具有等效声学特性但结构更为轻薄的复合超微孔微穿孔板结构。研究成果将为拓宽微穿孔板结构在高声强下的良好应用提供新思路。

本研究以拓宽微穿孔板吸声结构可有效应用的声压级范围为目的，开展了高声强下基于结构参数设计的非线性效应抑制研究。结合理论分析、数值模拟与实验研究，首先，建立了高声强下超微孔微穿孔板的半经验非线性声阻抗模型。基于该模型，探索了结构参数对可定量描述非线性效应抑制效果的临界声压级的影响规律,并揭示了基于单层超微孔微穿孔板的非线性效应抑制机制。然后在基础上，研究了针对给定的高声压级应用环境，可根据实际降噪需求进行非线性效应抑制的单层超微孔微穿孔板结构工程化设计方法。最后，提出了简单复合超微孔微穿孔板结构和多空腔复合超微孔微穿孔板结构，相比于单层超微孔微穿孔板，它们在制造成本更低、结构和重量更小的情况下，可实现更好的非线性效应抑制效果。本研究为微穿孔板在高声强下的实际应用奠定了理论和实验基础。