水下加筋单/双层回转组合壳-轴耦合声振建模与机理研究

Vibrations of hull, which are generated by propeller forces, mainly control low frequency noise of submarines, and the noise is difficultly reduced. Studying vibro-acoustic characteristics of submarines due to propeller forces is conducive to control the radiated noise from the source or is the basis for reduction of vibration and noise. In this context, the titled problem is proposed. By developing a theoretical model of shaft-hull system and conducting model experiments, strong- and weak-coupling factors and coupled vibro-acoustic mechanism are investigated. The main content of present project includes: a unified dynamic model for vibro-acoustic analysis of underwater submerged combined single- and double-walled shells of revolution, a semi-analytic dynamic model for coupled vibro-acoustic analysis of underwater hull-shaft system, coupled vibro-acoustic mechanism of shaft-hull system due to propeller forces, experimental analysis of a double-walled cylindrical shell coupled with plates and beam. Differing from adopting single-walled combined shells to model the hull and adopting beams or springs to model foundations in previous works, a high-efficient and normative model, which is more consistent with the hull of submarines of our country, is established and corresponding professional software is developed. A concept called as 'Holistic modeling, discrete analysis' is proposed to study and reveal coupled vibro-acoustic mechanism of shaft-hull due to propeller excitations. The results are expected to provide a new tool to predict vibro-acoustic responses of submarines and theory instructions for structure-borne acoustic design of submarines.

螺旋桨激励引起的轴-艇耦合振动是产生潜艇低频噪声的主要原因，难以抑制。开展螺旋桨激励下潜艇声振机理研究，有助于从源头控制轴-艇辐射噪声或为减振降噪提供依据。鉴于此，本课题提出“水下加筋单/双层回转组合壳-轴耦合声振建模与机理研究”。通过建立水下轴-艇声振半解析理论模型并结合模型试验，开展螺旋桨激励下轴-艇强、弱耦合因素及耦合声振机理研究。具体内容：水下加筋单/双层回转组合壳声振一致动力学模型研究；水下轴-艇耦合声振半解析动力学模型研究；螺旋桨激励下轴-艇耦合声振机理研究；双层圆柱壳-板-梁模型振动试验。本课题理论模型突破了以单层组合壳模拟艇体、以弹簧/梁模拟推力轴承基座等不足，形成了高效、规范且符合我国国情的潜艇声振预报新方法及专业计算软件；提出“整体建模、离散分析”思路探索并揭示螺旋桨激励下轴-艇耦合声振机理。研究成果有望为潜艇声振预报提供新手段、为潜艇结构声学设计提供理论指导。

低速巡航状态下螺旋桨脉动力经推进轴系引起艇体振动是产生潜艇水下低频辐射噪声的重要原因，开展螺旋桨激励下潜艇声振机理研究，有助于从源头控制轴-艇辐射噪声或为减振降噪措施提供依据，具有重要学术价值和军事意义。首先，以加筋单/双回转组合壳为简化潜艇模型，结合壳体理论、幂级数法和Helmholtz边界积分方程，构建了可实现水下加筋单/双层回转组合壳声振预报一致动力学模型，通过与FEM/BEM预报结果对比验证了模型的正确性。其次，采用有限元方法建立了由螺旋桨、推进轴系及推力轴承基座等组成的推进系统模型，并采用Kuhar动力缩聚法获取推进系统控制方程，结合虚拟弹簧技术实现壳体与推进系统快速耦合，进而建立了水下轴-艇耦合声振半解析动力学模型；通过与FEM/BEM结果对比验证了模型的正确性；以经验证的动力学模型为基础，采用Matlab GUI编制了水下单/双层回转组合壳-内部结构声振预报软件。再次，分析不同激励、舷间流体、推进系统与壳体耦合刚度等对艇体声振特性影响，以揭示螺旋桨激励下结构声振特性机理，结果表明：实肋板是内外壳间振动传递的主要通道；艉轴承刚度对结构声振响应显著、中间轴承刚度影响几乎可忽略；推力轴承基座与壳体耦合节点的轴向、周向和径向位移是决定二者耦合状态的主要因素。最后，设计并加工梁-板-双层圆柱壳模型，开展不同激励下有无舷间水模型振动测试，通过对比理论模型结果和试验测试结果进一步证明本课题动力学模型的正确性。本课题完成时，申请软件著作权1项，发表论文14篇，其中SCI收录论文13篇、EI收录1篇。