Marine Riser Vortex Induced Vibration Suppression Method

In this paper, the state of the art of study on the vortex-induced vibration of pipe riser is summarized. Research methods and progress used in VIV analysis are introduced. Empirical theory total with numerical simulation methods and experimental methods about VIV is introduced in this paper. Vortex-induced vibration phenomenon of cylinder which is placed in a uniform flow is simulated by software FLUENT, explorative study about the inhibitory effect of VIV for the use of wavy wall on the right half surface of cylinder which is free in XY plane is made, transverse displacement response of deep-sea flexible pipe riser with different in-flow speed is calculated in time domain, the modal stimulation process of pipe riser is analyzed, and wavy wall is used on deep-sea flexible pipe riser to suppress the VIV. The main work and important conclusions of this paper are listed as follows:1) A comprehensive review and analysis about the advance of VIV research at home and abroad is performed. Correlation parameters of fluid, structure and coupling movement of fluid and structure involved in the study of VIV are systematically introduced.2) Mechanical modal of cylinder which is elastic supported within XY plane and free in X and Y directions is established. Methods used to calculate flow field and the dynamic response are introduced. Coupling process of VIV of the cylinder is described by flowcharts.3) Study about the inhibitory effect of VIV for the use of wavy wall on the right half surface of cylinder, it's found that tail vortex of cylinder is related with the wall fluctuated direction, the displacement response of cylinder is influenced by the frequency of wall fluctuation, and it can be reduced down to 0.05D for cylinder with different reduced velocities, the wavy wall could be used to eliminate vortex in tail flow field, and vortex amassed in the narrow area that near symmetry line of X direction flow field.4) The finite element method used for the solution of dynamic response of deep-sea pipe riser is introduced. A code for Newmark-βmethod is programed using C language and is verified the calculation accuracy by numerical example.5) The flexible deformation of pipe riser caused by VIV is simulated with the method of strip technique. The process of modal evolution of pipe riser in the uniform current is analyzed . The results show that transverse displacement response of riser with wavy wall is greatly minimized and the coverage rate and arrangement of wavy wall have a great influence on the displacement response of riser.