基于CFD方法的FDPSO锥型垂荡板阻尼特性

Damping Characteristics of Cone Heave Plate on FDPSO Based on CFD

针对一种新型锥型浮式钻井生产储卸油装置(Floating Driuing Production Storage and Offloading System,FDPSO),从抑制垂荡和纵摇运动的角度分析得到结构的最佳垂荡板形式。运用基于势流理论的AQWA软件对FDPSO进行短期预报,确定不同海况下结构垂荡和纵摇运动形式。以计算流体力学为理论基础,通过模拟浮体单自由度简谐强迫运动,分析垂荡板锥角大小对结构垂荡、纵摇的附加质量和阻尼系数的影响。从涡量场角度分析阻尼板对周围流体的作用效果。结果表明:在一年一遇和百年一遇海况下,对于垂荡运动的抑制,锥角越小效果越好;对于纵摇运动的抑制,不同海况条件下都体现出10°锥角其优越性,锥角远离10°则纵摇无因次阻尼下降;对比阻尼板周围涡量场分布随运动的变化,分析得出涡的生成、发展和脱落与结构的周期性运动相关。

For a new type of cone Floating Drilling Production Storage and Offloading system(FDPSO),the optimal form of the heave plate is analyzed from the viewpoint of suppressing the heave and pitch motion.A short-term prediction of FDPSO is carried out using the software AQWA based on potential flow theory,and the motion forms of heave and pitch of structures under different sea states are determined.The effect of cone angle on the additional mass and damping coefficient of heave and pitch is studied based on the theory of computational fluid dynamics and through the simulation of forced simple harmonic motion with single degree of freedom of the floating.The effect of damping plate on the surrounding fluid is analyzed from the view of vortices field.In once per year and once per one hundred years sea conditions,the results show that:the smaller the cone angle is,the better the suppression effect of heave motion is;for the suppression of pitch motion,different sea conditions both reflect the superiority of the cone angle at 10 degrees;when the cone angle is away from10 degrees,the dimensionless damping of pitch will decrease;in contrast with the variation of vorticity field distribution along the damping plate,the generation,development and shedding of vortices are related to the periodic motion of the structure.