【作者】 于飞；

【导师】 陈心昭；

【作者基本信息】 合肥工业大学 ， 机械设计及理论， 2005， 博士

【摘要】 本文围绕产品噪声测量与控制这一日益受到关注的课题,开展了关于近场声全息技术(NAH)和声学灵敏度分析方面的研究。近场声全息技术,诞生于20世纪80年代初,通过在辐射体的近场测量声压数据可以重建和预测出整个三维空间声场的声学量,如声压、质点振速、声强以及远场指向性等。因其具有此优点,近场声全息技术迅速地成为一种声源识别和声场可视化的强有力工具。在过去的二十多年中,该技术也取得了很大的发展,形成的全息变换算法主要有:空间声场变换(STSF)、边界元方法(BEM)和Helmholtz方程最小二乘法(HELS)。本文在实现和改进基于STSF方法的NAH技术基础上,提出了空间声场分离技术,为克服BEM和HELS方法的缺点,提出可应用于内、外声辐射问题分析的基于波叠加方法(WSA)的NAH技术。而在声学灵敏度分析方面,本文通过对波叠加公式进行关于设计变量的求导,提出基于波叠加方法的三维声学灵敏度分析。每章内容简要概括如下: 第一章回顾近场声全息技术和声学灵敏度分析的发展历史,分析了二者的研究现状和存在的问题,在此基础上提出了这些问题的解决途径,确定了本文的主要研究内容。 第二章实现基于STSF的近场声全息技术,解决该技术中的若干关键问题。采用特殊函数和分离变量法推导出平面、柱面和球面NAH技术的理论公式,并讨论它们的数值实现算法,以及全息重建过程中的误差传递。最后,进行扫描全息测量的实验验证工作,提出一种不需要先验或后验知识的截止波数选取方法。 第三章提出空间声场分离技术,拓宽基于STSF的近场声全息技术的使用范围。从近场声全息原理出发,利用声波沿不同方向传播的特点,针对平面、柱面和球面全息测量建立了波数域内的声场分离公式。利用声场分离技术分离后的全息声压,可以不受背景干扰地重建目标源面上和声场中的声学参量。 第四章给出声辐射问题的声学基础和定解问题描述,推导出边界Helmholtz积分方程,随后给出了边界Helmholtz积分方程的离散化形式——边界元方法,以及在离散化实施过程中存在的问题和相应的处理方法。在此基础上,推导出波叠加方法的基本公式,论证了波叠加方法和边界元方法之间的等价性关系,最后给出波叠加方法的实施过程和精度分析。 第五章提出了基于波叠加方法的近场声全息技术。依据波叠加积分公式,通过离散化连续虚源方法来改进简单源替代方法,并引入混合层势理论,建立了一种稳健的全波数空间声场重构技术。研究声全息重建过程中的不适定性问题,以及相应的正则化策略。通过典型算例和实验验证了理论分析的正确性,并研究了声源频率及虚源位置等对重构精度的影响。更多还原

【Abstract】 Since noise measurement and control engineering are attracting more and more attentions, near-field acoustic holography (NAH) and acoustic sensitivity analysis have been investigated in this dissertation. Near-field acoustic holography which was proposed in the beginning of 1980s, can reconstruct and predict acoustic quantities such as sound pressure, particle velocity, sound intensity and far-field directivity in the whole 3-D field without the resolution limitation by recording the sound pressure in the near-field of radiator. Because of such special features, the NAH technique becomes one of the most powerful tools to identify sound sources and visualize sound field. Meanwhile, the technique have achieve many progresses in itself, and its implementation algorithms mainly consist of spatial transform of sound field (STSF), boundary element method (BEM) and Helmholtz equation least-square method (HELS). Based on the implementation and enhancement of the STSF-based NAH, sound field separation technique has been proposed in this dissertation. In order to overcome the shortcomings of the BEM and HELS based NAH, wave superposition approach (WSA) based NAH has been proposed and applied to the analysis of interior or exterior sound field. As far as acoustic sensitivity analysis, wave superposition approach (WSA) based acoustic sensitivity analysis has been proposed by differentiating wave superposition formulation with respect to design variables. The main contents in the dissertation are summarized as follows:In chapter one, the history of NAH and acoustic sensitivity analysis has been reviewed, and the current status and problems existed in them have also been analyzed. Then the solutions to these problems have been presented and the main research content has been determined in the dissertation.In chapter two, the STSF-based NAH has been implemented and some problems of it have been solved. The theoretical formula of planar, cylindrical and spherical NAH have been deduced according to special function and variable-separating method. Meanwhile, the numerical algorithm and error transmission have been discussed in this chapter. Finally, an experiment using scanning holographic pressures has been conducted, where a cut-off wave-number determination method has been proposed without prior or post knowledge.In chapter three, sound field separation technique has been proposed, which widen the applicable scope of the STSF-based NAH. According to the NAH theory and propagating characteristics along different directions, sound field separation technique can be established in the wave-number domain. The acoustic quantities on the target source surface and in the field can be reconstructed without the influence ofthe background noise using the separated pressures.In chapter four, the theoretical basis and description to determine solution hasbeen given, and Helmholtz integral equation and its numerical form that is boundary element method have been deduced. Based on these, the basic formulation of WSA has been deduced and its equivalence to BEM has been verified. In the end, the implemented process and precision analysis have been given.In chapter five, the WSA-based NAH has been proposed. According to wave superposition formula, a robust reconstruction method has been established for all wave numbers by introducing hybrid layer potential theory. The ill-posed nature of holographic process and its regularization strategy has been investigated deeply. The correctness of theoretical analysis has been verified through numerical simulations and experiments. In addition, influence of frequency and factitious source position to reconstruction precision has been investigated.In chapter six, wave superposition formulation in cavity has been deduced, and the WSA-based interior NAH and its implementation method using isotropic parameter interpolation have been established. The results of several typical simulations show that the calculated result can coincide with the theoretical values very well after regularization, even if the data including measurement errors is used to reconstruct and predict, and the Tikhonov method can obtain a little bit better effect than the truncated singular value decomposition (TSVD) method.In chapter seven, the 3-D acoustic sensitivity analysis theory and its implementation algorithm have been developed. According to WSA, the relation between acoustic quantities in field and acoustic and spatial parameters on product surface can be established. Then the analytical formulation of acoustic sensitivity analysis can be obtained by differentiating with respect to design parameters. Finally, the calculation equation can be obtained through the discretization of the analytical formulation. Several simulations have been taken to test the feasibility and effectiveness of the WSA-based acoustic sensitivity analysis.In chapter eight, researches in this dissertation have been summarized, and the topics need further study have been proposed.更多还原