基于柔性微穿孔板的通风管道主被动复合吸声机理及关键技术研究

The broadband noise control of flow duct is the critical component in the low noise design of industrial system and national defense, and has important strategic significance and scientific value for prevention of environmental noise and national defense security. However conventional control methods are not suit for complex acoustical environment and broadband noise control in flow duct. This project plans to use flexible micro-perforated panels (MPPs) in hybrid sound absorption system for flow duct noise control. The effect of grazing flow to the sound absorption structure will be revealed, and then the matching and optimization strategy of multi-absorption mechanisms will be proposed for broadband noise control. The optimization strategy of grazing flow duct with impedance boundary will be studied, and then the control target for active sound absorption system will be proposed. The simulation models based on multi-physics (structure, fluid, acoustic) will be established. The modified impedance model of flexible MPP under grazing flow will be proposed according to experimental analysis. The interaction mechanisms between the vibration deduced by flow and the impedance of the MPP will be explored. Then, the theory of flexible MPP will be improved and the applied range will be widened. The sound absorption model of the hybrid system will be established. The matching and optimization strategy for wideband noise control will be proposed. With the balance of structure parameters, acoustical parameters and active control strategy, the sound absorption mechanisms of structural resonance absorption, Helmholtz resonance absorption and active absorption will be positively coupled. This hybrid system will provide wideband sound absorption and break through the bottleneck of existing systems. The research achievements will provide a theoretical base and technical support for design of new type broadband silencer.

通风管道的宽频带噪声控制是工业系统和国防装备低噪声设计的关键环节，对环境噪声防治和国防安全都具有非常重要的科学意义和战略价值。然而目前的控制方法无法满足通风管道复杂声学环境与宽频带控制的要求。本课题拟提出基于柔性微穿孔板的主被动复合吸声理论，通过揭示管道切向流效应对柔性吸声结构的影响规律，提出多吸声模式优化匹配方法，实现宽频带噪声控制的目的。首先建立阻抗边界的管道声学模型，提出主动吸声系统目标阻抗；建立切向流效应下多场耦合模型，结合实验分析，提出柔性微穿孔板阻抗修正模型，分析流致结构振动对微穿孔板声学阻抗的影响规律，完善微穿孔板阻抗理论并拓宽其应用范围；建立复合结构吸声模型，提出系统匹配策略，协调结构参数、声学参数及控制策略等因素，使结构共振吸声、Helmholtz共振吸声与主动系统吸声正向耦合，突破现有复合吸声技术中频控制效果不理想的技术瓶颈，为新型消声器设计提供重要的理论和技术支撑。

通风管道是工业系统和国防装备的重要组成部分，其噪声控制技术对于环境噪声防治和国防安全都具有非常重要的战略意义和科学价值。目前，降低通风管路噪声的最主要途径是采用阻抗复合式消声结构能实现较宽频带内噪声控制。然而，由于被动控制技术固有的缺陷，其低频控制性能存在明显的局限性，主要表现在控制频带窄、控制频率不能调节、体积重量大等方面。. 近年来，主动噪声控制发展迅速，相对于被动控制方法，更适用于一般难以解决的超低频噪声抑制问题，且设备小，更新方便，对于通风管道，还具有不产生流量损失的优点。但是目前主动控制技术还面临着系统复杂、中高频控制效果差等问题，而且在通风管道中，由于气流对传声器的扰动将导致控制系统不稳定、使用周期缩短等现象，限制了主动噪声控制技术在通风管道中的应用。. 本课题首先基于模态分解及有限元法建立了有限尺度阻抗边界的管道声学模型，并通过进化算法求得主动吸声系统目标阻抗，分析了切向流、敷设长度、敷设方式对最优阻抗的影响规律；采用微穿孔板作为被动吸声层，分析其结构参数与声学参数的相互作用规律，提出微穿孔板与目标阻抗匹配的方法，确定其主要参数。建立主动吸声理论模型，分析阻抗匹配和压力释放两种控制方法的适用条件，采用FXLMS自适应算法，在MATLAB/SIMULINK中进行仿真。最后搭建了通风管道主被动复合吸声试验系统来验证理论分析的准确性。结果表明通过结构共振吸声、Helmholtz共振吸声与主动系统吸声正向耦合，实现宽频噪声控制。