柔性立管涡激振动响应轨迹特性研究

Study of the trajectory performance on the vortex-induced vibration response of a flexible riser

为了深入研究细长柔性立管的涡激振动响应特性,进行了柔性立管的拖曳水池试验。由拖车拖动立管产生相对来流,根据应变测试得到的应变数据,基于模态叠加法得到位移响应。试验分析前,通过数值方法先针对刚性立管的涡激振动响应轨迹特性进行了分析。紧接着,通过试验方法对柔性立管的单模态以及多模态涡激振动响应轨迹特性进行了深入的分析和讨论。通过分析发现:柔性立管在低速下具有与刚性立管类似的轨迹响应特性,均呈现经典的8字形状;柔性立管在高速下,其轨迹开始变得混乱,这主要是由位移的多模态响应特性所产生。

Laboratory tests were conducted on a flexible cylinder in order to further improve the under-standing of the response performance of the vortex-induced vibration （ VIV）. The experiment was carried on in a towing tank and the relative current was simulated by towing the flexible riser in one direction. Based on the modal superposition method, the VIV displacements were obtained from the measured strain. Before the experiment, the trajectory performances of the VIV on a rigid riser were studied by the numerical method. Furthermore, the motion trajectories of the single-mode and multi-modes VIV on a flexible riser were dis-cussed using the experiment method. The analysis results indicate that the motion trajectory for the flexible riser at a low velocity displays a typical type-eight figure, which is very similar to that for a rigid cylinder. However, with the increased velocity, the motion trajectory for the flexible riser becomes chaotic, which is induced by the multi-mode VIV responses.