潮流与风对单点系泊系统运动稳定性的影响研究

Effect of wind and tidal current on motion stability of single point mooring system

应用时域仿真的方法研究了风与潮流作用下单点系泊系统的非线性动力学特性。以三阶操纵运动方程为基础,引入定常的风力、潮流作用力和二阶波浪力,建立了系泊系统三自由度运动微分方程,据此建立了系泊系统的多自由度计算机仿真模型。风与潮流联合作用的情形下,对一艘单点系泊油轮的动力学行为进行了数值仿真研究。以潮流速度和系缆长度为分岔控制参数,在参数平面上给出了油轮系泊运动的Hopf分岔集,它将参数平面分为两个系统动力学行为本质不同的区域。研究表明,与潮流(顶流)单独作用的情形相比,顶风条件增加了油轮静止系泊位置的Liapunov稳定性。

By using uniform tidal current forces, wind forces and steady second order wave forces, the mathematic model of three degree-of-freedom （3-DOF） of mooring systems was established based on a nonlinear three order vessel maneuvering mathematical model, which included the surging, swaying and yawing motions of the moored vessel. A computer simulation model of 3-DOF motions of mooring systems was also built. Time domain simulations were carried out with a tanker exposed to tidal current and wind. Hopf bifurcation characteristics were discussed while the tidal current velocity and mooring line length were defined as bifurcation control parameters. Then the bifurcation set was found in the parameter space according to the classifications of the dynamic responses of the moored ship. The parameter plane could be divided into two par.ts by the bifurcation set. There were different motion modes when bifurcation control parameters are in the different areas of the parameter space. It is shown that the eqilibrium mooring position becomes more stable under the sense of Liapunov when the tanker is exposed to head wind and tidal current.