关键词: Newmark法, 激波器, 流固耦合, 特征线法, 液压激波, 有限元法

Abstract: To study dynamic characteristics of pipe vibration under hydraulic excitation force generated actively, at first mathematical model of pulsating fluid is established and a computer code based on the method of characteristics (MOC) is developed to simulate it. Then the vibration equation is derived considering the fluid-structure interaction, after which the pipe is simplified as beam model and analyzed by finite element method(FEM), where the nodes of the fluid adopted by MOC are coincided with that of the pipe by FEM. Using Newmark method, the dynamic response at every cross section of the pipe is worked out. Besides, an experimental system that axial direction of the pipe with elastic supports is designed to verify it. The numerical simulations show that a simple harmonic motion arises at every cross section of the pipe, but where excitation force is inverse trends with flow velocity. The lateral vibration amplitude of every node along the pipe increases as the rising system pressure, but the lateral vibration amplitude lags behind the excitation force obviously. Meanwhile, axial vibration frequency of the pipe is far higher than that of the excitation force due to the axial spring. Measured data is basically consistent with the numerical simulations. Some coupling relationships between fluid dynamic parameters and pipe vibration are revealed. So, this work is expected to provide some theoretical basis for two dimensional vibration characteristics of pipe and some exploratory study on its controllability.

Key words: Finite element method, Fluid-structure interaction, Hydraulic excitation force, Newmark method, The method of characteristics, Vibration exciter