随机波中船舶参数横摇研究

A study on parametric rolling in irregular waves

针对随机波中船舶参数横摇,提出一种数值预报方法。采用新的随机波成形方法,求解出船舶无横倾时在随机波中时间序列垂荡和纵摇运动,确定出船-波相对位置。利用3个坐标系之间的转换关系确定船体各横剖面左右舷与波面瞬时交点,然后对波浪压力沿船长湿表面积分,得出船舶复原力的Froude-Krylov部分。提出复原力之辐射力和绕射力部分和横摇角的非线性假定。确定一个参数横摇数学模型,实现随机波中参数横摇计算;通过试验和数值模拟对一艘巴拿马型集装箱船进行了参数横摇预报,研究了随机波中参数横摇的实际非各态历经的特点。

One method is proposed for predicting parametric rolling in irregular waves. A new method is used to make irregular waves profile. The relative position of ship to irregular waves is determined with heave and pitch motions obtained by a strip theory applied to an upright hull. A general method for calcu- lating intersections between ship and irregular waves is presented base on transform of three coordinate systems, and then the nonlinear Froude-Krylov component of restoring variation is calculated by integrating wave pressure up to wave surface. The hydrodynamic effects of restoring variation is nonlinearly extrapolated with regards to the roll angle by using radiation and diffraction force acting on a heeled hull. Finally, an ex- ample of parametric rolling prediction for a post-Panamax containership is done by using experiment and simulation and the ＂practical non-ergodicity＂ of parametric roll in irregular waves is investigated.