串列双立管涡激振动抑制研究

实际工程中深海立管常以管群的方式出现，当立管彼此相互靠近时，会发生流场干涉效应。为研究立管间相互干涉作用及螺旋侧板抑制双立管涡激振动的效果，本文基于Ansys Workbench平台，采用双向流固耦合技术对Re=7800均匀来流下长径比为482的串列双立管进行三维数值模拟。结果表明，立管轴间距为5D时立管间有完整的涡旋脱落，下游立管在上游立管的尾流诱导下产生振动，双立管横向振动锁定在二阶模态，且振动方向相反。附加螺旋侧板能有效削弱双立管振动频率，降低上游立管横向振动幅值，但下游立管两向位移响应变化不大。

Research on VIV suppression of intandem double risers

In the practical engineering, the deep sea riser is often used in the form of tube group. When the riser is close to each other, the flow field interference effect occurs. In order to study the interaction between risers and investigate the ef-fect of helical strakes on vortex-induced vibration suppression, based on Ansys Workbench platform, a two-way fluid-solid coupling technique is applied to perform a three-dimensional numerical simulation for intandem double risers under uniform flow with Re=7 800. The ratio of length to diameter is 482. The results show that when the distance between the two risers is 5D, there is complete vortex shedding between the two risers. Induced by the wake flow of the upstream riser, the down-stream riser vibrates, and the two risers all locked in second mode with opposite direction of vibration in cross flow. With helical strakes fixed, vibration frequency of the double risers are effectively reduced, and the upstream riser' amplitudes in cross flow is suppressed. But the strakes have little effect on the displacement response of the downstream riser.