输流管道的流体诱发振动稳定性分析

考虑内、外部流体的联合作用,研究输流管道的流体诱发振动稳定性。将外部流体的作用简化为涡激升力,利用Kane方法建立输流管道的二维非线性涡激振动方程。将动力学方程在平衡位置附近线性化,进行输流管道的稳定性分析。探讨不同内外流流速、外部流体的粘滞力系数、管道跨度以及内外流联合作用对管道稳定性的影响。研究结果表明,非线性涡激振动模型更真实地反映输流管道的流体诱发振动稳定性,在内流和管道跨度的影响下,发生耦合模态颤振现象;外部流体粘滞力系数的变化对管道的动力特性有明显的影响;在内外部流体的联合作用下管道的振动特性与各因素单独作用时明显不同。

Stability analysis on flow-induced vibation of fluid-conveying pipes

Considering the effect of the internal and external fluid excitation, the flow-induced vibration stability of fluid-conveying pipes were investigated. The role of the external fluid was simplified as vortex-induced lift, and the nonlinear differential equations were derived based on Kane’s equation. The equations of motion are linearized in the neighborhood of the equilibrium position to carry on the multimode linear stability analysis. The effect of internal and external fluid velocities, fluid-added damping coefficient, and span length on the vibration stability is discussed. The results obtained show that non-linear flow-induced vibration model is a true reflection of the fluid-induced vibration stability of fluid-conveying pipes. Under the influence of internal fluid and span length, the coupled-mode flutter takes place; The external fluid-added damping coefficient changes has significant impact on the dynamic characteristics of the pipe；under the combined effects of fluid inside and outside the pipe, vibration characteristics significantly different from the role of each factor alone.