干扰环境下非稳态任意形状声源的自由场还原方法研究

Non-stationary nearfield acoustical holography (NS-NAH) is usually restricted to the free field condition. However, the practical sound fields contain not only the non-stationary target source, but also the disturbing source and the scattered sound caused by the disturbing waves falling on the surface of the target source, which lead to the problem that when NS-NAH uses the mixed pressure to reconstruct the sound fields, the non-stationary target source cannot be identified precisely. The application of NS-NAH in the non-free field is seriously restricted. .In order to overcome these limitations, this project will propose a free-field recovery method based on the interpolated time-domain equivalent source method, which can efficiently and simply realize the accurate identification of the non-stationary arbitrarily-shaped sources in the non-free field. In this project , the separation algorithm of the non-stationary sound fields based on the interpolated time-domain equivalent source method is first established for removing the influence of the disturbing source. Then, on the basis of the separation algorithm, an eliminating algorithm of non-stationary scattered sound is established for removing the influence of the scattered sound and recovering the pressure radiated by the target source alone. Finally, the recovered pressure is used the input of NS-NAH for identifying the non-stationary source. On the basis of these theoretical studies, an identifying system is developed for the non-free field conditions and will be used for the experimental study. The studies in this project are expected to promote NS-NAH off the anechoic room environment and realize the accurate identification of the non-stationary arbitrarily-shaped noise source in the practical engineering environment, and to further provide an important means for the noise and vibration control of the mechanical and electrical product.

现有的非稳态近场声全息（NS-NAH）主要针对自由场条件，而实际声场环境还会存在干扰声以及干扰声在目标声源表面产生的散射声，导致NS-NAH在利用混合声压进行声场重建时无法准确识别非稳态噪声源，因此严重制约了NS-NAH在非自由场条件下的应用。.鉴此，本项目拟提出一种基于插值时域等效源法的自由场还原方法，实现NS-NAH在非自由场条件下对非稳态任意形状声源的精确识别。该方法首先建立基于插值时域等效源法的非稳态声场分离算法，去除干扰声的影响；然后在此基础上，建立非稳态散射声消除算法，消除散射声的影响，还原出目标声源单独辐射的声压；最后以此作为NS-NAH的输入进行非稳态声源的识别。基于以上理论，研制一套相应的声源识别系统，并开展实验研究。本项目的研究成果有望使得NS-NAH走出消声室环境，实现工程环境下非稳态任意形状声源的精确识别，为机电产品的噪声振动控制提供重要的技术手段。

鉴于由于实际声场环境会存在非稳态干扰声以及干扰声在目标声源表面产生的非稳态散射声，使得非稳态近场声全息无法在非自由场条件下准确识别噪声源，而频域自由场还原方法无法实现非稳态声场还原这些问题，本项目提出了干扰环境下非稳态自由场还原方法，实现了非稳态近场声全息在非自由场条件下对非稳态任意形状声源的精确识别。首先提出了基于时域等效源法的非稳态声场分离方法，以去除存在测量面另一侧干扰声源的影响，实现了任意形状声源的非稳态声场分离；再在非稳态声场分离基础上，提出了基于双面声压测量的非稳态自由场还原方法，消除了刚性边界条件下非稳态散射声的影响，彻底还原出目标声源单独辐射的非稳态声场，同时提出了基于单面声压-质点加速度测量的非稳态自由场还原方法，也实现了刚性边界非自由场条件下非稳态声场的实时还原；然后将还原的声学量作为非稳态近场声全息的输入，提出了基于时域等效源法的结构表面时域振速重建方法，实现了任意外形声源的结构表面瞬态振动的重建，并以此进行任意形状声源在非自由场条件下的识别，可用于实际声场环境下现场分析目标声源的时变辐射特性和振动特性；进一步地深入分析方法中各参数的影响，特别是分析了方法中时间推进求解过程所产生的非稳态问题，提出了多步计算的非稳性抑制方法；最后基于上述所提方法研制了噪声源识别系统，并成功应用于弯曲激励板结构表面瞬态振动的重建和非自由场条件下装有扬声器铁板辐射的非稳态声场还原。本项目的研究成果可以使得非稳态近场声全息走出消声室环境，应用于工程环境下噪声源的精确识别，为机电产品的噪声振动控制等研究提供重要的数据支持和技术保障。在本项目资助下已在国际权威刊物和国内外学术会议上发表论文10篇，其中被SCI收录7篇，EI收录8篇，项目负责人以第一作者身份发表SCI论文6篇；申请国家发明专利3项，授权1项，实审2项；协助培养硕士研究生6名，均已获硕士学位。