变张力细长柔性立管涡激振动响应特性数值研究

A numerical study based on a wake oscillator model was conducted to determine the vortex-in⁃ duced vibration (VIV) responses of a flexible riser with an axial time-varying tension. Three different flow types including a linear shear flow, an exponential shear flow and a real stepped flow were considered. The coupling equations of a structural oscillator and a wake oscillator were solved by using a standard central fi⁃ nite difference method of the second order. The VIV response characteristics including the structural dis⁃ placement, structural frequency, displacement envelope and displacement evolution for the three different flow profiles were systematically compared. After that, for each flow profile, the effect of the different tension models on the VIV characteristics was further researched. The numerical results indicate that both the VIV displacement and VIV frequency in a real stepped flow have very different characteristics from those in a lin⁃ ear shear flow, and that, compared with the corresponding VIV characteristics in a real stepped flow, the VIV displacement in an exponential shear flow is very similar while the VIV frequency in an exponential shear flow is obviously different.