浅水深对160kDWT FPSO水动力系数的影响

FPSO系泊于浅水中时,由于安全性问题,浅水深对其运动与载荷的影响正逐渐引起重视。本文利用三维线性势流理论和源汇分布法研究一艘160kDWTFPSO在浅水中的辐射问题,对不同水深下FPSO的水动力系数进行了数值计算。结果表明,浅水深时,一方面,3个垂向运动(垂荡、横摇和纵摇)附加质量有显著增加,特别是水深吃水比减小到1.3后,更是以几何倍数增长;另一方面,6自由度运动的阻尼系数均有明显增加,特别是横摇阻尼系数,随着水深吃水比的减小而成倍数增长。由于浅水中水动力系数的显著增加,FPSO垂向运动幅度也必将较大地趋于缓和,从而不易导致浅水FPSO碰底现象的发生。

The effects of shallow water depth on the hydrodynamic coefficients of a 160kDWT FPSO

The effects of shallow water depth on the motions and loads of FPSO are paid more and more attention due to the safety problems. By using the 3-D linear potential theory, the radiation problem of a 160kDWT FPSO in shallow water is investigated and the hydrodynamic coefficients in various water depths are calculated numerically. It is shown that the added masses of heave, roll and pitch motions and the damping coefficients of all the motions increase remarkably in shallow water. Especially, when the ratio of water depth and draught is less than 1.3, the added masses and roll damping increase sensitively and rapidly with the decrease of the ratio. Therefore, the vertical motions of the FPSO will be much less in such shallow water and the event of touching sea bottom rarely occurs.