在波浪和洋流的作用下，深水立管两侧会出现周期性的漩涡脱落，这一现象极易引发涡激振动，使得立管出现疲劳损伤，显著降低其服役寿命。同时，当立管间距较近时，还会产生流场干涉效应。为研究立管之间的相互干涉作用及螺旋列板对双立管涡激振动的抑制效果，本文采用大涡模拟（LES）的方法，对Re=3 900均匀来流下的串列双立管的涡激振动响应进行三维数值分析。并针对不同的立管间距（3D，5D，8D，D为立管直径）以及附加螺旋列板的情况，建模分析了立管的水动力系数，并进一步探究了螺旋列板对双立管涡激振动的抑制效果。研究结果表明：对于串列双立管情况，下游立管受到上游立管尾涡和自身漩涡脱落的影响，升力系数幅值较单立管时更大。在3种立管间距工况中，立管间距为3D时下游立管升力系数最大，8D时升阻力系数接近单立管情况。附加螺旋列板能有效抑制双立管涡激振动，双立管升力系数明显减小，从而减少了立管的振幅响应。附加螺旋列板双立管之间的相互作用与光滑双立管之间的相互作用总体趋势相似。并且由于列板的分流作用，彻底破坏了立管的脱涡方式，在立管后形成了间距很小，近乎平行的尾涡。
Deepwater riser in waves and currents suffer from a periodic vortex shedding, which can cause vortex-induced vibration(VIV) and the structural fatigue damage. When the riser is close to each other, the flow field interference effect occurs. In this paper, we investigate the interaction between risers and the effect on suppressing VIV of helical strakes. Three-dimensional numerical analysis is carried out for the smooth tandem double risers and the fixed tandem double riser with helical strakes at Re=3900 by large eddy simulation (LES).In view of the different riser spacing (3D, 5D, 8D, D as riser diameter) and additional helical strakes case, the hydrodynamic coefficients of riser are analyzed, further exploring the effect of helical strakes on Vortex-induced Vibration of Double risers. The results show that the lift coefficient of downstream riser is maximum in case that the spacing of riser is 3D, the drag coefficient and lift coefficient are the same as that of the singe riser in case of 8D. The lift coefficient and the amplitude response of the double riser is significantly reduced after adding the helical strakes. Due to the shunting effect of the helical strakes, the vortex removal method of the riser was completely destroyed, and a very small parallel nearly trailing vortex appeared behind the riser.
2019,41(4): 100-105 收稿日期：2018-11-02
DOI：10.3404/j.issn.1672-7649.2019.04.019
分类号：O35
基金项目：国家自然科学基金资助项目（11872174）
作者简介：李艳潇(1993-),女,硕士研究生,研究方向为计算流体力学
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