变质量矩形贮箱流固耦合系统动力学特性分析  

Dynamic Analysis on a Fluid-Structure Coupling System with Variable Mass in a Rectangular Tank

作　　者：马驰骋[1] 张希农[1] 罗亚军[1] 张春林[1] 

机构地区：[1]西安交通大学机械结构强度与振动国家重点实验室,西安710049

出　　处：《西安交通大学学报》2014年第7期109-116,共8页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(11172225;11102147);国家自然科学基金青年基金资助项目(11302160)

摘　　要：为了研究质量减小(燃料消耗)过程中矩形贮箱的动力学特性,提出了一种基于PATRANNASTRAN-MATLAB的建模仿真方法。根据虚拟质量法对变质量矩形贮箱流固耦合结构进行简化,建立了结构动力学有限元模型;结合PATRAN-NASTRAN-MATLAB对该动力学模型进行计算仿真,求得了系统的位移响应;鉴于傅里叶变换在处理非稳态信号时的不足,使用ChoiWilliams时频分布处理变质量系统的动力学响应信号,得到了时频响应谱图。结果表明:系统质量的减小在引起系统振动频率增大的同时还产生了一个附加的负阻尼,使得系统的振动衰减减慢;系统质量减小引起的负阻尼与系统的质量变化率成正比,如果系统的质量变化较快,就会产生一个比较大的负阻尼,当负阻尼的作用超过结构阻尼的作用时,将使系统的振幅增大,甚至会超出贮箱结构的弹性范围,造成结构的破坏。To investigate the dynamic characteristics of a rectangular tank with decreasing mass（fuel consumption）,a numerical approach is proposed to model and simulate the fluid-structure coupling system based on PATRAN-NASTRAN-MATLAB.Virtual mass method is utilized to simplify the model and to construct the finite element model,then free vibration states of the variable mass system are mainly analyzed.The displacement responses and frequency responses of the time varying mass system are obtained by using a PATRAN-NASTRAN-MATLAB program.Considering the deficiency of Fourier transformation,Choi-Williams transformation is adopted to process the non-stationary vibration signals of the time varying mass system.It indicates that the decrease in the mass of the system induces an increase in the vibration frequency of the system and generates an additional negative damping to slow up the vibration decay.The additional negative damping is proportional to the rate of mass variation,and it will result in larger vibration amplitude of the system if it plays a dominant role over the structural damping.Especially,once the increasing amplitude exceeds the elastic range,the tank structure may be damaged.

关 键 词：液体火箭 变质量 矩形贮箱 流固耦合 Choi-Williams时频分布 负阻尼 

分 类 号：V214.3[航空宇航科学与技术—航空宇航推进理论与工程]