液压激波作用下管道流固耦合的动力学建模

Dynamic Modeling and Experiments for Fluid Structure Interaction in Pipe Under Hydraulic Shock Wave

为了研究在主动液压激波作用下管道振动的动力学特性,设计了一种液压激波变频控制系统,建立了激波作用下充液管道流固耦合的动力学模型.采用特征线-有限元法,用Newmark法编程,将由特征线法求得的流体各断面横向压力载荷施加到管道有限元的单元节点上,由此求得了管道横向各断面处及轴向的振动时程曲线,并通过快速傅里叶变换获取了管道横向及轴向的幅频特性曲线.试验发现,在激波作用下,充液管道的横向与轴向振动中基频的幅频特性吻合较好,而高阶频率由于谐波干扰信号非常严重,因此与数值模拟结果没有明确的对应关系.

To investigate dynamic characteristics of fluid filled pipe under hydraulic excitation wave generated from a newly developed shock exciter, a hydraulic excitation system with frequency converter is designed, the dynamic model of fluid structure interaction for fluid-filled pipe is established, and the pressure and flow velocity of fluid distributed along the pipe are evaluated with method of characteristics. The numerical simulations show that the transverse excitation force gets simply harmonic at each cross section along the pipe and can be controlled almost linearly via adjusting the system pressure. Then method of characteristics-finite element is chosen to distribute the transverse excitation force on the finite element nodes of the pipe, and the time-history curves of transverse and axial excitation are plotted. The amplitude-frequency character of transverse and axial excitation is gained by FFT and compared with the measured data by threeaxis acceleration transducer. It is found that the fundamental frequencies are basically consistent with each other, while the high order frequencies do not coincide due to the high frequency interference.