多孔材料声学表征的时域CFD法及其在飞机复合声衬应用的研究

In recent years, China has focused on the development of large civil aircraft projects. However, China's large aircrafts still have serious cabin acoustic comfort problems, which directly harm its reputation in domestic and foreign markets. Porous material is an important component of the silencer on the aircraft. The hybrid liner of the aero-engine intake employs a layer of porous material to achieve its broadband noise reduction performance. It's found that the time-domain CFD method is obviously superior in analyzing the impact of airflow on the acoustic characteristics of silencers. Therefore, this project proposes a time-domain CFD method for acoustic characterization of porous materials to analyze the acoustic characteristics of hybrid liners in meanflow. Firstly, a method for extracting Johnson-Champoux-Allard (JCA) model parameters of porous materials based on acoustic measurements is established. Secondly, the thermodynamic equations of the equivalent fluid model of porous materials are corrected by JCA model parameters, and the improved 2D and 3D time-domain CFD methods for acoustic characterization of porous materials are established. Further, the time-domain CFD method is used to analyze the acoustic characteristics of the local model and the complete model of an aero-engine hybrid liner under the intake flow respectively and a verification mechanism based on local liner experiment is established. Finally, by comparing with traditional sound-absorbing material, the application prospect of porous woven material in the hybrid liner of aero-engines is explored.

我国近年重点开发民用大飞机项目，而我国大飞机的舱内声学舒适性问题仍然较为严重，这直接影响其在国内外市场的声誉。多孔材料是飞机上消声装置的重要组成部分，发动机进气道的复合声衬就采用多孔材料层以实现其宽频消声性能。时域计算流体动力学法（CFD）在分析平均流对消声元件声学特性的影响时具有明显的优势，因此本项目拟研究一种多孔材料声学表征的时域CFD法，分析复合声衬在平均流作用下的声学特性。首先建立一种基于声学测量的多孔材料Johnson-Champoux-Allard（JCA）模型参数提取方法；其次用JCA模型参数修正多孔材料等效流体模型的热力学方程，完善多孔材料声学表征的二维和三维时域CFD法；然后用时域CFD法分别分析飞机发动机复合声衬的局部模型和完整模型在进气流作用下的声学特性，建立基于局部声衬实验的验证机制。最终通过与传统吸音棉对比，探索多孔编织材料在飞机发动机复合声衬的应用前景。

本项目针对目前我国大飞机的舱内噪声大，声学舒适性较差、声学分析优化的仿真和实验方法不完善等问题，系统深入地开展了多孔材料声学表征的时域CFD法及其在飞机复合声衬应用的研究、多孔材料声学超辐射特性研究和大飞机舱内外声场复现研究。主要开展了以下的研究内容并取得了良好的研究成果。. （1）基于无流条件下局部多孔材料消声量的实验测量和仿真计算结果，提取多孔材料的JCA模型参数，建立基于消声量的JCA参数的声学实验测量方法，该方法相比于已有的基于传递损失的实验测量方法更加简单高效；. （2）采用JCA模型参数修正多孔材料等效流体热力学方程，采用改进的CFD法计算由多孔材料组成的消声装置在进、排气气流作用下的消声量、传递损失和传递矩阵，该方法相比于传统方法具有更广泛的适用性；. （3）采用时频域混合仿真方法，计算含多孔材料消声装置的插入损失，并建立基于插入损失的有流条件下多孔材料声学仿真分析的实验验证机制，该方法相比于传统方法更具有工程实用性；. （4）搭建多通道相位阵列声源系统，生成携带角动量的旋转声波，采用静止传声器阵列实验测量新型多孔材料结构的声学超辐射特性，该实验装置和方法相比于已有方法更加简便，且在飞机噪声控制、微弱信号侦测和水下高速声学通讯具有一定的应用前景；. （5）搭建基于最小二乘法的多通道声场复现系统，在大飞机C919全尺寸模拟舱的机舱内外复现接近大飞机实际噪声环境的声场特性，建立大飞机声学舒适性评估的试验环境，相比于传统方法，该实验方法更加简便且具有更小的复现误差。

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