极端环境下多孔金属及结构耦合非线性声学性能研究及结构设计

In this study, the application of light porous metals and their innovative structures under extreme conditions such as high-temperature nacelles of aircraft are focused on. Therefore, the non-linear coupling sound dissipation and the absorption mechanism of porous metals and their compound acoustic liners under the following typical conditions are investigated in detail: the airflow with high Mach(>0.2),varying high temperature fields(<700℃),and high intensity sound(>140dB)impinging .Further, the acoustic liners with innovative structures are designed and optimized based on above work. Compared with single physical fields, the mechanisms of sound dissipation and absorption of porous metals and their structures in multiple physical coupling fields are apparently more complex. Many nonlinear mutual effects such as the macro airflow, the acoustic velocity of air in pores in media, the contours of acoustic field and temperature field, the convection of involved physical variables, the thermodynamic process of air, etc., would be considered at the same time. Thus this study starts from the basic pore and the solid cylinder acoustic model, and then attempts to strictly deduce a coupling nonlinear wave motion equation and acoustic impedance equation of media in pores in porous metals and their compound structures by means of using basic control equations of fluid mechanics. Hereafter, the effects of temperature, airflow, finite acoustic amplitude, etc., on the sound propagation and absorption can be explored using numerical simulation,analytical methods and experimental measurements. Finally, the dissipation mechanism of the sound energy and the noise reduction of porous metals and innovative acoustic liners will be found out theoretically.

本课题以轻质多孔金属及其创新构型在飞机发动机高温消声短舱等极端环境下的工程应用为研究背景，拟针对强气流(Ma>0.2)、复杂高温(<700C℃)、高声压(>140dB)激励多耦合场作用下的轻质多孔金属及其复合声衬的耦合非线性声能耗散和吸收机理以及创新构型声衬的设计及优化开展研究。强气流、高温、高声压耦合互致的多孔材料及结构声能耗散和吸声机制明显较单一物理场情况复杂，需同时考虑宏观气流场、填充介质质点声学速度、声场、温度场分布对流项及相互耦合行为、气体热力学过程等诸多复杂非线性因素的影响。拟考虑从基本微孔或绕流模型入手，考虑强气流、高温、高声压激励多耦合作用因素，根据流体基本控制方程严格推导填充介质的耦合非线性波动方程和声阻抗方程，通过数值模拟和解析方法及实验手段研究声场、温度场、流场等物理量的变化和作用机制，最终揭示多孔金属及其创新构型的声能耗散机理和消声机制，为工程应用提供基础理论依据。

本项目以轻质多孔金属及其复合吸声结构在飞机发动机高温消声短舱等极端环境下的工程应用为研究背景，拟针对强气流(0.1-0.3)、复杂高温(300-700℃)、高声压(120-160Pa)激励多耦合场作用下的轻质多孔金属及其复合声衬的耦合非线性声能耗散和吸收机理以及创新构型声衬的设计方法及优化开展研究。本项目通过数值模拟和解析方法及实验手段研究声场、温度度、流场等物理量的变化和作用机制，最后揭示多孔金属及其创新构型的声能耗散机理和消声降噪机制，为工程应用提供理论基础依据。