【摘要】 基于格子Boltzmann粒子网格技术,采用XFlow求解器对三角分布的海洋立管进行涡激振动数值模拟。运用二阶范德波尔方程描述二维圆柱横向单自由度涡激振动,研究了三圆柱间距比及来流约化速度对圆柱涡激振动特性的影响,圆柱间距比取L/D=0.5、2.0、4.0,来流约化速度为U_r =1～9;分析了圆柱涡激振动的振幅、升阻力系数特性及圆柱尾流中旋涡脱落模式。结果表明:圆柱间距比为L/D=0.5、2.0、4.0时对应的上游圆柱涡激振动的锁振区间分别为U_r =3.5～7.0、3.5～7.5、3.5～6.0,最大振幅分别为Y_rms/D=0.372, 0.546, 0.470。间距比过大或过小时,其流体流动模式分别受接近效应和尾流效应的影响,中间间距比时,在非锁振区间内,其流体流动模式受两者组合效应的共同影响,在锁振区间,其流体流动模式同大间距比一样主要受尾流效应的影响;流体干涉效应的变化对圆柱升阻力系数的变化起着重要的作用,不同间距比,圆柱升阻力系数的变化趋势相似。更多还原

【Abstract】 Numerical simulation for vortex-induced vibration（VIV） of marine risers with triangular distribution was performed using XFlow solver based on the lattice Boltzmann particle grid technique. Transverse single-DOF VIV of a 2-D cylinder was described using the second order van der Pol equation, and effects of 3 cylinders’ spacing ratio and incoming flow reduction speed on VIV features of cylinders were studied. The cylinders’ spacing ratio L/D = 0.5, 2.0 and 4.0, and the incoming flow reduction speed U_r = 1-9. VIV amplitude of cylinders, features of lift-drag coefficient and vortex shedding mode in wake of cylinders were analyzed. The results showed that when cylinder spacing ratio L/D = 0.5, 2.0, and 4.0, upstream cylinder VIV’s locking vibration interval U_r = 3.5-7.0, 3.5-7.5 and 3.5-6.0, respectively, the maximum amplitude Y_rms/D = 0.372, 0.546 and 0.470, respectively; when cylinder spacing ratio is too big or too small, fluid flow mode is affected by proximity effect and wake effect, respectively; with medium spacing ratio, within a non-locking vibration interval, fluid flow mode is affected by combination of above two effects; within a locking vibration interval, fluid flow mode is mainly affected by wake effect; change of fluid interference effect significantly affects change of cylinder lift-drag coefficient; with different spacing ratios, change trends of cylinder lift-drag coefficient are similar.更多还原