Study Of Flow-Induced Vibration In Pipes On Offshore Platform And In Water

On the basis of the studies done on the vibration of fluid-conveying pipes in the world, the flow-induced vibrations of pipes on offshore platform and in water are studied in this dissertation. The mechanisms of flow-induced vibrations of the fluid-conveying pipes on offshore platform and in water are analyzed, the physical models and mathematical models of flows in pipes on offshore platform and in water are established, with the programs of numerical simulation, the flow of vibrating pipe, the force of flow-induced vibration in pipe on offshore platform and the lift and the drag of flow acting on the fluid-conveying pipe in water are solved, and the linear solution for equation of vibrating fluid-conveying pipe in water with the fixed supports in two ends is derived. The main work accomplished in this dissertation is as follows: On the basis of the theory of oscillating fluid mechanics and the parametric polynomial method, the flow-induced vibration of pipe on offshore platform is studied. The mechanism of vibration induced by flow in the fluid-conveying pipe on offshore platform is analyzed, the physical model and mathematical model of unsteady,incompressible, viscous flows in vibrating pipes with different cross-sections are established, flows of pipes in different flow conditions with the insignificant stimulations are solved. The results obtained are analysised and compared to experimental results referred to.According to the partial linearization theory of oscillating fluid mechanics and theory of Fourier transform, the flow-induced vibration of pipe on offshore platform is studied. The flows of pipes in the different conditions with the significant stimulations are solved. The results obtained are analyzed and compared to experimental results referred to. On the basis of the integral differential pressure method, the force of flow-induced vibration in pipe on offshore platform is studied. The formula for force of flow-induced vibration is derived, the forces of flow-induced vibrations in fluid-conveying pipes in the different flow conditions with significant stimulation are calculated according to the formula derived and the results obtained in the fourth chapter. The results obtained are analyzed.By use of grid-shaping skill and multi-grid solver, the flow-induced vibration of the fluid-conveying pipe in water is studied. The vibration mechanism of the fluid-conveying pipe in water is analyzed, the lift and drag acting on pipe in water are calculated. The results obtained are analyzed and compared to the experimental data referred to. According to linearizatin theory, the vibration response of the fluid-conveying pipe in water is studied. With the assumption of insignificant vibration and the results obtained in the sixth chapter, the linear solution for the motion equation of forced vibrating pipe with fixed supports in two ends in steady vibration is derived. On basis of this solution, the influence of flow to the vibrating pipe is analyzed and the method of obtaining resonant frequency and resonant time are given.