OUT-OF-PLANE VIBRATION OF CURVED PIPES DUE TO PULSATING FLUID FLOW

与直管输送流体的动力学相比，弯管输送流体的动力学研究较少。特别是在重力作用下柔性弯曲管道输送流体运动的非线性积分微分方程尚未导出，弯曲管道面外振动的实验结果尚未见。本文从理论和实验两方面研究了流体脉动作用下弯曲管道的面外振动问题。首先，计算了平面外振动的模态振型和固有频率作为一维流动稳态流体速度的函数。其次，研究了其静力平衡解随流体流动脉动分量的稳定性。第三，利用本文导出的柔性弯曲管非线性空间振动的非线性积分-微分方程对上述现象进行了讨论。最后利用图像处理系统测量了弯曲管道在脉动流体作用下的空间运动。

The dynamics of curved pipes conveying fluid are not so much studied which is compared with the dynamics of the straight pipe. In particular, the nonlinear integro-differential equations governing motion of flexible curved pipe conveying fluid are not yet derived under the influence of gravity, and there are no experimental results associated with the out-of-plane vibration of a curved pipe. In this paper, out-of-plane vibration of a curved pipe due to the pulsating fluid flow, has been investigated analytically and experimentally. First, mode shape and natural frequency of out-of-plane vibration was calculated as a function of the steady-state fluid velocity of the one-dimensional flow. Second, the stabilities of its static equilibrium solution depending on the pulsating component of fluid flow were investigated. Third, the above phenomena were discussed using the nonlinear integro-differential equations governing the nonlinear spatial vibration of a flexible curved pipe which have been derived in this paper. Finally the spatial motions of a curved pipe due to the pulsating fluid flow were measured by using the image processing system.