海洋立管的涡激振动会严重影响立管结构的使用寿命。通过室内水槽实验研究在立管模型周围等分布置三根附属控制杆来减小立管涡激振动响应的新型抑制措施。实验中观测了0.24m/s、0.31m/s、0.37m/s以及0.44m/s四种均匀流和两个极限来流方向下的涡激振动抑制效果。实验结果表明:三根附属控制杆抑制措施可明显降低立管模型的横向振动幅值,但对主管的振动频率改变不大;同时,这一抑制措施对来流方向有较强的适应性,避免了以往单根控制杆在流向发生改变时可能加剧立管涡激振动的弊端。
Vortex-induced vibration (VIV) of marine risers may significantly increase threats of structural fatigue failure. In order to suppress VIV, an effective passive flow control method is proposed in this work, which is accomplished by arranging three identical small circular cylinders close to the riser model with 120° angle. The riser model with control rods is placed in a water flume subject to four different current velocities and two extreme attack angles. The experimental results show that the control rods can remarkably reduce the transverse responses of the riser model while the vibration frequency of the riser model is almost the same as that of a bare riser. The experiments also demonstrate that the present flow control measure is not sensitive to the incoming flow direction, which is a very important advantage for practical engineering application.