基于半解析法的轴-浸没锥柱组合壳系统纵向-横向振动耦合特性研究

In the non-uniform wake field, submarine is excited by the propeller excitations and shell excitations, which leads to different coupling vibration of the propulsion shaft and the shell. It is the main reason of underwater sound radiation. Propulsion shaft and supporting bearings are the important routines of the vibration transmission. In the most existed analytical researches on the shaft-shell model, shaft vibration or shell vibration is the main considered part and only propeller excitation is considered. Based on these researches, this project takes the submarine structure as the object and chooses a propulsion shaft with a submerged conical-cylindrical shell as the simplified theoretical model. Analytical method is used to describe the longitudinal-transversal coupled vibration of the conical-cylindrical shell and the multi-span shaft. Longitudinal and transversal continuity conditions are built at the supporting bearings. Then the equations are solved by numerical method. Thus, an effective semi-analytical method is formed to solve the longitudinal-transversal coupled vibration of the system. Longitudinal or transversal propeller excitations at the shaft end and point or surface excitations on the shell are all considered in this research. The coupling effects between different vibration forms and different sub-structures vibration of the system are analyzed. Furthermore, two-way transmission of the vibration between shaft and shell are put forward. Calculation of energy distribution and importance ranking of different routines of vibration transmission under the excitations at shaft end and on the shell are included by power flow method. The aim of this research is to reveal the vibration characteristics and transmission of the submarine structure, which can supply the theory basis and the technical supports of optimizing submarine and controlling vibration and sound radiation of submarine.

在不均匀伴流场中，潜艇受到螺旋桨激励和艇体外部激励的作用，使推进轴系和艇体产生多种形式的耦合振动，是产生水下声辐射的主要原因，而推进轴系及其轴承是纵、横向振动传递的重要途径。现有的轴系-艇体相关解析法建模研究大多侧重于轴系振动或壳体振动且仅考虑螺旋桨激励，本项目以潜艇结构为研究对象，以轴-浸没锥柱组合壳系统为简化理论模型，采用解析法对锥柱组合壳及多跨梁的纵-横耦合振动建模，在轴承支撑处建立纵、横向连续条件，通过数值算法求解，以形成有效的系统纵向-横向耦合振动半解析求解方法；研究中计入轴端螺旋桨纵、横向激励和艇体外部的面激励和点激励，分析系统不同振动形式之间和不同子结构振动之间的耦合作用；提出轴与壳体间的双向振动传递，采用功率流方法对轴端和壳体外部激励下不同振动传递路径进行能量分布计算及重要性排序；旨在揭示潜艇结构的振动特性及传递关系，为潜艇的优化设计和减振降噪提供理论依据和技术支持。

声振特性是衡量水下舰艇先进性的重要指标之一，对水下舰艇结构振动进行机理研究，并以此为理论依据降低其航行噪声，具有重要工程意义。本项目针对潜艇结构的振动问题，将推进轴系简化为多跨梁，艇体简化为锥柱组合壳，轴承简化为弹簧结构，理论抽象为轴-锥柱组合壳模型，形成针对潜艇结构复杂耦合振动性能的半解析计算方法，研究了其在螺旋桨和艇体外部激励作用下的振动特性。. 首先，分别采用欧拉-伯努利梁理论及Flügge壳体理论建立了推进轴系和锥柱组合壳的振动方程，将径向轴承和推力轴承简化为弹簧结构，在轴承处建立了轴-壳之间横向及纵向连续条件，联立形成轴-壳耦合系统横/纵向振动方程，并通过有限元/边界元方法验证了其正确性，分析了真空及水中轴-壳耦合系统横/纵向振动特性，得出：轴-锥柱组合壳系统表面流体起到了增加附加质量及阻尼作用，使得系统共振频率降低、振动幅值减小；无论激励在壳体表面还是轴系端部，壳体与轴系的位移大小处在同一数量级，即轴承作为壳体与轴系主要的连接部件，在振动传递中的作用不可忽视；轴-壳的耦合作用首先发生在较低频范围，随着轴承刚度的增大，耦合作用的频率范围也逐渐增大，达到一定刚度时，轴和壳两者位移响应接近一致。. 其次，在轴-壳耦合系统受迫振动方程的基础上，基于功率流理论，研究了以轴端螺旋桨激励、艇体外部激励为能量输入的系统振动双向传递特性，分析不同激励对轴-壳耦合系统横/纵向振动功率流传递的影响，对不同路径的振动传递进行讨论，得出：螺旋桨激励或壳体激励下，横向振动能量传递大于纵向振动能量传递，且由螺旋桨流向轴的功率流大于壳体流向轴的功率流。. 最后，搭建了小尺度轴-壳耦合系统试验模型，并结合已有的加载和测量装置，设计轴-壳耦合模型振动试验并进行试验测量，验证半解析法的正确性。. 本项目形成了有效的轴-浸没锥柱壳复杂系统振动的半解析求解和传递特性分析方法，为水下舰艇的振动及其传递特性分析提供理论及技术支持。