A Research Of The Dynamics Of A Pipe Conveying Flow By Numerical Calculation

The extended water hammer equation as well as the lateral motion equation based on the Timoshenko beam model of a pipe conveying fluid is given, known as the 8-equation-model of FSI(fluid –structure –interaction) system. The lateral motion equation of pipe, concerning the effects of the Coriolis force and the centrifugal force of the flow, is developed through Newton method and Hamilton Principal. The basic principle of the transient dynamics analysis software Dytran is introduced as well as the concepts and commands to operate FSI analysis. The method of characteristics is applied to investigate the dynamic response of the reservoir pipe valve system.The Poisson coupling and the junction coupling effects on the response of the system are discussed through the comparison with the results derived from the classical water hammer equation.Using the Laplace transform-matrix-method, the analysis of the dynamics of an elbow subjected to two different boundaries is established. The effect of boundary condition on FSI dynamics response is analyzed.The spectral element method is applied to obtain the natural frequency of the lateral motion of the FSI system of a simple supported straight pipe conveying flow. The frequency and time responses of the same pipe system at critical flow speeds when divergence and flutter occurs are also given.The Galerking method is applied in the dimensionless equation to investigate the natural frequency of the simple supported pipe system changing with the flow speed. The relation of the critical flow speed and the mass ratio of a clamped-clamped system are also given. The area of the existence of the simple parametric resonance of a pipe conveying harmonically perturbed flow is determined by the Bolotin method. The influence of the mass ratio and flow velocity on the area is analyzed.