【作者】 白振国；

【导师】 俞孟萨；

【作者基本信息】 中国舰船研究院 ， 船舶与海洋结构物设计制造， 2014， 博士

【摘要】 本文针对双层圆柱壳体舷间振动和声辐射问题，开展了双层圆柱壳的舷间振动噪声传递机理、声振控制方法研究，采用模态展开法，建立了有限长双层加肋圆柱壳的振动和声辐射数学物理模型，分析了舷间水介质和连接结构的功率传递特性，提出了水下空气管隔声层和隔振实肋板控制措施，并通过模型试验验证了隔声层和隔振实肋板的降噪效果，为舷间声振控制提供了理论依据和解决方案，具有明确的工程应用背景和较高的实用价值。主要研究内容及创新点如下：针对双层壳体、横舱壁、环肋、周向连续实肋板、周向离散实肋板、龙骨、舷间声学覆盖层、舷间水层及外场水介质组成的复杂耦合系统，采用状态矢量概念和阻抗矩阵表达式，建立了以壳体振动模态位移矢量为变量的耦合系统振动矩阵方程，通过各子结构和声介质阻抗矩阵的增减，可以实现不同子结构对舷间声振耦合特性的分析；利用有限元软件分步校验了子系统建模方法。推导了舷间水层和实肋板的功率传递公式，计算分析了舷间水层、实肋板的功率传递特性，明确了舷间声振传递特征规律：0.5倍环频以下频段，双层壳体间功率传递以舷间水层传递为主，舷间水层传递的声功率比实肋板传递的声功率大10dB以上；0.5倍环频以上频段，实肋板传递的声功率对声辐射峰值的贡献更为明显；要控制低频声辐射，应以抑制舷间水层的声功率传递为主，要控制中高频声辐射，则应以控制实肋板声功率传递为主。提出了声学覆盖层敷贴在三维圆柱壳体的轴向波数扩展修正方法，在此基础上，提出了基于声阻抗测量的声学覆盖层的多层等效声阻抗模型，拟合了声学覆盖层的多层等效参数，计算了敷设声学覆盖层的圆柱壳振动和声辐射特性，分析了声学覆盖层应用于舷间的降噪效果，结果表明：声学覆盖层应用于舷间的降噪效果主要体现在300Hz以上频段，300Hz左右有2-3dB的降噪效果，700Hz以上有7dB以上的降噪效果，300Hz以下频段，声学覆盖层的降噪效果不明显。针对舷间水介质层和实肋板的声功率传递特征，提出舷间声振隔离措施，采用气管隔声层控制声传递、圆弧夹心型实肋板控制振动传递，计算分析了控制措施的降噪效果，并在大尺度双层圆柱壳模型上进行了试验验证，试验结果表明：100Hz以上频段，舷间声振隔离具有较好的降噪效果，使双层壳体的辐射声功率降低了2-10dB，为实现舷间声振传递控制提供了新技术。将简单双层壳体舷间声振耦合进一步扩展到多圆柱壳，计算分析了多圆柱壳结构的舷间共振耦合特性和辐射声场分布，揭示了50Hz以下低频段多壳体之间的共振声场耦合现象，明确了三圆柱壳的声遮蔽效应主要体现在正横方向，且随频率升高愈来愈明显；并针对三圆柱壳舷间声场耦合特性，提出了阻抗失配原理的列管式隔声单元，可在低频达到较好的隔声效果，200Hz隔声量达到5dB，2000Hz隔声量达到15dB以上。更多还原

【Abstract】 Sound and vibration problem of the medial space of double shells is focused in thisdissertation, and the research on the sound and vibration transfer mechanism of medial space ofdouble shells together with its control methods are carried out. Modal expansion method isadopted to establish the math-physical model for the sound and vibration problem ofdouble-layer ribbed cylinder of finite length. Based on the power transmission characteranalysis of medial water layer and connecting structure, sound and vibration insulationstructure of air pipe layer and annular connected plates is presented. The noise reduction effectof sound insulation layer and vibration isolation annular connected plates is verified by modeltest, which provides theoretical foundation and practical solution for sound and vibrationcontrol problem of medial space of double shells. The work has specific engineeringapplication background and is practically useful. The main research content and innovation areas follows:Aimed at the complex coupling system consist of double layered shells, bulkhead plates，ring rib，annular connected plates，circular discrete connected plates，keel，acoustic coatingbetween medial space of double shells, medial water layer and outside acoustic medium，theconcept of state vector and impedance matrix expression is adopted to establish the vibrationmatrix equation of coupling system with modal displacement vector of vibrating shell asvariable. The modification of control function is achieved by increasing or decreasing theimpedance matrix of sub-structure and acoustic media which facilities the analysis of the effectof different sub-structure on the sound and vibration coupling character of medial space ofdouble shells. Every step of sub-structure modeling method is checked out by FEM software.The sound power transmission model of medial water layer and annular connected platesis established, the transmitting characteristics of sound power of medial water layer and annularconnected plates is analyzed with the model, which shows that the medial water layerdominates the sound power transmitting between double shells below the half ring frequency,10dB of the sound power over the annular connected plates by, while above the half ring frequency, the annular connected plates take the predominance of sound radiation power. As aresult, to reduce the sound radiation in low frequency, the sound power transmitted by medialwater layer should be taken into account superiorly; as for the sound control in mid-highfrequency, the vibration and sound transmission of annular connected plates should beconcerned.To investigate coupling of acoustical coating and cylindrical shell, the axial wave numberexpansion correction method is proposed, then the multiple layers equivalent impedance modelof acoustical coating by measurement of acoustical impedance is raised from the correctionmethod. The characteristics parameters of multiple layers acoustical coating are interpolated,then the vibration and sound radiation of cylindrical shell with acoustical coating is simulated,as well as the noise reduction in medial space of double shells. The analyze results show thatthe noise reduction induced by the acoustical coating works above300Hz, and the noisereduction is about2-3dB around300Hz, while more than7dB above700Hz. However, thenoise reduction of acoustical coating is ineffective below300Hz.According to the acoustic power transmission character of medial water layer and annularconnected plates, complex sound and vibration isolation methods for medial space of doubleshells are introduced: air pipe as isolator to reduce sound transmission, arc-section sandwichconnected plates to reduce vibration transmission. The noise reduction effect of complex soundand vibration isolation methods are calculated and analyzed. A large scale double-layer circularshells model is adopted in the experiment to verify the calculation results. Experiment resultsshow that, complex sound and vibration isolation methods bring good noise reduction effects inthe frequency span more than100Hz, the radiation power of double-layer circular shell modelreduced2-10dB. All the results show that complex sound and vibration isolation methods arenew technology to control the sound and vibration transmission of medial space of doubleshells.Sound and vibration coupling model of medial space of double shells is extended tomulti-shell model, the oscillation coupling character and radiation sound field distribution ofmulti-shell model are calculated, the calculation results show that, oscillation couplingphenomenon of multi-shell exists under50Hz, the sound masking effect of three-shell exists at abeam direction, and become larger when the frequency rise. According to the sound fieldcoupling character of three-shell, pipe-array sound isolation model are designed based onimpedance mismatching, which bring good sound isolation effects in low-frequency,5dB at200Hz,15dB at2kHz.更多还原