华中科技大学 硕士学位论文 船舶输流管系振动特性研究 姓名：徐合力 申请学位级别：硕士 专业：动力机械及工程 指导教师：蒋炎坤 20080327 I 摘 要 船舶动力装置系统存在着输送各种介质的管道系统，如压载水系统、冷却水 系统、燃油输送系统、滑油输送系统、压缩空气系统等，而各种不同管径的管道 纵横交叉布置在甲板和机舱里，流体通过泵的作用不断的在管道内流动，这种流 体流动过程产生的脉动可能引起管道的振动，进而降低管道输送效率，引起结构 振动疲劳，甚至由此导致管系结构破坏，造成重大经济损失，更有甚者可能对船 舶安全航行造成威胁对于潜艇来说，振动引起的噪声将会降低其隐蔽性，影响 航行安全鉴于此，本文对船舶输水管道中流体引起的振动问题进行了研究，通 过分析管道振动产生的原因及影响管道振动的因素，并运用有限元法对管系进行 了模态分析和强迫振动分析，同时进行了试验验证，提出相应改造措施主要工 作包括： （1）阐述了船舶输流管道一维流动特性及波动理论，建立了一维波动方程，并 运用波动理论及其方法，分析了管道内液体产生脉动时，管道截面上脉动压力 P 和脉动速度 V 随管道截面位置变化的关系，由此推导出计算管道内液柱振动的固 有频率表达式。
并对一端封闭另一端敞开管道（对应于船舶上一端接水泵，另一 端接船舶水舱，如船舶压载系统的情况）内液柱固有频率进行了分析 （2）分析了引起管道振动的各种因素，并着重研究了管道流体压力脉动产生的 原因及计算方法，以及由此对管道系统产生的激振力，指出压力脉动是引起管道 振动的主要原因并模拟一段弯曲管道，应用有限元法对输流管道进行流体动力 学分析，计算流体通过弯曲管道时，其压力、流速的变化及对管道所产生的附加 作用力情况 (3)对输流管道横向自由振动数学模型进行了推导，并分析了管内流体流速与 管道系统固有频率间的关系，随着流速的增加，管道的固有频率降低，当流速达 到临界流速时，管道发生失稳，但在分析船舶输水管系时，流体流速与临界流速 相比，管道内流体的流速很小，由此结论可知，在计算管系振动时，可不考虑流 速对管道固有频率的影响分析了用有限元对管道进行模态分析的方法，分别计 算了1 DOF和2 DOF约束的充液管道自由、无激励状态下的固有振动频率 （4）建造了一段船舶输水管道实验系统，通过 PRO/E 完成几何建模，建立了 输水管系及其支承的有限元模型，用 ANSYS.10 软件对管道系统进行模态分析，计 II 算管道自由、无激励状态下的固有振动频率。
同时分析计算了管道内流体流动压 力及流速的分布情况以及流体液柱振动的固有频率 （5）实测管道内压力脉动幅值，应用有限元法计算了管道内液体激振力作用 下的振动的响应 （6）对实验管道系统进行了压力、振动测量，得出其功率谱图，并对管道系 统的振动、压力脉动信号进行了检测处理，分析了管道振动的原因 (7)应用理论与实验分析的结果指导船舶管系优化设计，给出设计管系的合理 步骤和方案主要考虑各段管道的长度、弯曲角度、不同支承条件、液体流速等 因素对管道振动的影响，并给出了多种防振、减振措施 关键词：关键词：输流管道 压力脉动 振动 模态分析 有限元法 减振降噪 III Abstract There are many kinds of pipes which are used to transport medium in ship power plant systems such as the ballast water system, the cooling water system, the fuel transportation system, the lubricating oil transportation system and the pressure air transportation system. These pipes in different diameters are fixed vertically and horizontally in the engine room and on the deck. The liquids continually are pumped to their application places respectively. The piping vibration, which might give rise to lower the pipeline transportation efficiency, may be much severe due to fluid pulsation. Furthermore, the piping vibration may easily lead to the structure fatigue, destroying the ship or the serious economy lost. As for a submarine, the pipeline vibration and noise of may influence its concealment system and safe navigation. Thus the ship pipeline vibration should be further analyzed, including reasons and effect factors of vibration, FEM (Finite Element Method) analysis of modal and enforced vibration, experiment verification and some how to decrease vibration. The following contents are mainly included in this study: 1). the one-dimension fluid characteristics of and wave theory are applied to the ship transportation pipelines by setting up one-dimension wave equation to analyze the mutual relation among the fluid pressure and velocity fluctuations along the pipeline while the liquid is in pulsating transportation. The expression equation on the pipeline natural frequency is derived; in the meantime, the liquid vibration in the pipe where one end is closed and the other end is opened has been analyzed as one representative example. 2). various influencing factors of causing pipeline vibration have been analyzed. Furthermore, the generation reasons and corresponding calculation method on the pipeline fluid pulsation have been mainly analyzed and got; in the meantime, the exciting force to the pipeline may be the main cause to the pipeline vibration. As for one example of one bending pipe, the Finite Element Method (FEM) method has been introduced to calculate the fluid pressure and velocity fluctuations along the pipeline and its additional force to the pipeline while there being liquid passing through. 3).The mathematical model of the pipeline free transverse vibration has been set up in this study to analyze the influencing relation between the fluid velocity and the pipeline natural frequency. With the fluid velocity increasing, the pipeline natural frequency may be decreased; while the fluid velocity approaching the critical velocity, the pipeline may be in instability. On the other hand, the pipeline natural frequency may not be influenced IV by the fluid velocity because the fluid velocity is generally much lower than its critical velocity for the ship water transportation pipeline system. The fluid pipeline natural frequencies in the free and no excitation state with 1 DOF and 2 DOF constraints have been calculated by using the Finite Element Method (FEM) for modal analysis. 4). for verifying the calculation results, an experiment plant of the ship water transportation pipeline system has been set up. In the meantime, the geometrical model to the ship water transportation pipeline system has been built up by introducing PRO/E and the modal analysis has been carried out by using the software of ANSYS.10. The fluid pipeline natural frequencies in the free and no excitation state has been calculated; furthermore, the fluid pressure, velocity and natural frequency along the pipeline have been got. 5). the peak of the fluid pressure fluctuation in the ship water transportation pi。