深吃水圆筒型浮式核能平台涡激运动数值模拟

Numerical simulation of vortex-induced motions of a deep draft cylindrical floating nuclear platform

深吃水圆筒型浮式核能平台是一种新型多功能高效平台,可有效解决南海岛礁开发过程中的能源供给问题。在一定来流速度下,尾流区交替泄涡进而诱导平台发生涡激运动(vortex induced motions,VIM),这将严重加速系泊和立管系统疲劳损害,同时对平台内部核反应堆运行产生不利影响。基于改进的延迟分离涡方法(improved delayed detached eddy simulation,IDDES)对平台在不同折合速度下的横荡、纵荡、艏摇运动响应进行数值模拟,并从水平面内质心运动轨迹、运动频率、三维流场特性等角度分析涡激运动关键特征。研究结果表明:当折合速度5.45<Ur<9.08时,平台横荡、艏摇振幅均逐渐增加且运动轨迹类似“香蕉”形,横荡与艏摇运动频率基本一致且横荡未出现明显的“锁定”区间变化;当7.26<Ur<9.08时,艏摇振幅近似线性递增且运动频率中主频附近出现多个峰值,运动轨迹在顺流方向上逐渐变宽;三维流场中发现尾流区三维漩涡结构相当复杂且平台底部柱靴结构对表面流动分离造成干扰,柱靴结构具有一定的减涡效果。

Deep draft cylindrical floating nuclear platforms are a new type of multi-functional and efficient platforms,which can effectively solve the problem of energy supply in the development of offshore islands and reefs in the South China Sea.At a certain inflow velocity,the wake area will induce vortex-induced mo⁃tions(VIMs)of a platform,which will seriously accelerate the fatigue damage of the mooring and riser system,and adversely affect the operation of nuclear reactors inside the platform.Based on the improved delayed de⁃tached eddy simulation(IDDES),the sway,surge and yaw motion responses of a platform at different reduced speeds were numerically simulated,and the key characteristics of vortex-induced motions were analyzed from the perspectives of motion trajectory,motion frequency and three-dimensional flow field.The results show that when the reduction speed of Ur ranges between 5.45 and 9.08,the amplitude of sway and yaw in⁃creases gradually,the motion trajectory is similar to a“banana”,the frequency of sway and yaw is basically the same,and there is no obvious change of“locking”interval in sway.However,when 7.26<Ur<9.08,the amplitude of yaw increases approximately linearly with several peaks appearing near the dominant frequency,and the motion trajectory gradually widens in the downstream direction.In the three-dimensional flow field,it is found that the three-dimensional vortex structures is quite complex,and that the skirt structure at the bottom of the platform interferes with the surface flow separation,which results in a certain vortex reduction.