导流板对海底管线下沉自埋及涡振影响

Study on sinking of self-burying and vortex vibration of submarine pipeline with spoiler

为研究导流板对海底管线的下沉、自埋及涡振的影响,采用ANSYS软件流固双向耦合数值模拟方式分别对无导流板、30°、60°、90°夹角安装导流板的海底管线进行模拟计算,并通过现有试验结果对比验证数值模拟的可行性。模拟分析得到不同方式安装导流板的海底管线附近压力分布云图、流场分布云图、管线所受升力、拽力曲线、应力变化曲线及下沉变形量曲线。结果表明:海底管线上安装导流板,使得管线上下表面的海流区域形成压力差,压力差随导流板的夹角增大而增大;但传统90°夹角安装导流板的海底管线后侧压力产生波动,使管线产生涡激振动,存在疲劳破坏隐患;60°安装导流板海底管线,下沉变形量出现趋恒现象;管线下方流速最大,冲刷海床形成凹陷,为管线下沉创造条件,同时管线后方回流带起的泥沙对管线形成自埋。

In order to study the sinking of self-bury and vortex vibration of the submarine pipeline"with spoiler,the fluid and solid bidirectional coupling numerical simulation method was adopted.The simulation calculations in several cases,such as the seabed pipelines without spoilers,and 30 degrees,60 degrees and 90 degrees installed spoilers were carried out respectively.The feasibility of the numerical simulation was verified by the comparison of the existed experimental results.Through simulation analysis,the pressure distribution nephogram,the flow field distribution nephogram,the lift and dragon force curve of the pipeline,the stress variation curve and the subsidence deformation curve near the submarine pipeline were obtained under different installed degrees of spoilers.The results show that,the spoilers of the submarine pipeline make the pressure difference appear between the upper and lower surfaces of the pipeline,and the pressure difference increases with the increase of the installation angle of the spoilers.However,the rear pressure of the submarine pipeline with spoilers installed at 90 degrees is fluctuating,which causes the vortex vibration of the pipeline,and there is a hidden danger of fatigue failure.The sinking amount of submarine pipeline with spoilers installed at 60 degrees approaches a constant,and the maximum velocity appears below the seabed pipeline.Thus the fluid can crash the seabed which makes it hollow and cause pipeline sinking.The pipeline can be buried by the sediment taken up by the rear pipeline back-flow.