航空发动机空间管路系统的流固耦合振动特性

为了分析航空发动机空间管路系统的振动特性，提出了一种采用自定义管单元建立输液管路流固耦合有限元模型的方法.模型中的自定义管单元考虑了管路的横向流固耦合振动、轴向振动和周向扭转振动.管路系统中的支承采用非线性弹簧单元模拟.通过将自定义管单元的仿真结果与试验测试数据和经典理论解进行比较，验证了自定义管单元的正确性.研究了实际空间管路系统振动固有频率和响应特性.研究表明:随着内压增大，固有频率和临界流速均减小.同时得出了非线性刚度系数和激励幅值对管路系统简谐激励下受迫响应的影响规律. 

Dynamic characteristics of aero-engine pipe system considering fluid-structure coupling

For analysis of dynamic characteristics of aero-engine pipe system, a fluid-structure coupling dynamic model using the user-defined three-dimensional (3D) pipe element was proposed based on the finite element method. The flexural fluid-structure coupling, axial and torsional dynamic behavior of the pipe was considered in the user-defined pipe element. The support was modeled using the nonlinear spring element. The user-defined pipe element was verified through comparisons with the measured data and analytical results. The natural frequencies and responses of a pipe system were calculated. The results show that the natural frequencies and the critical velocity decrease as the fluid pressure increases. And the effects of the nonlinear stiffness coefficient and the excitation amplitude on the pipe system under harmonic base excitation can be obtained.