规则波中参数横摇直接稳性评估方法研究

Study on the direct stability assessment method of parametric roll in regular waves

国际海事组织(IMO)正在制定第二代完整稳性衡准,其中参数横摇是非常重要的稳性失效模式。为提供一种计算可靠且便于工程应用的参数横摇直接稳性评估方法,该文采用一种实用的三维时域方法进行规则波中船舶参数横摇运动研究。在该方法中,应用组合Rankine源和时域格林函数的混合源法求解辐射势和绕射势,对船体平均湿表面进行压力积分求解辐射力和绕射力,而Froud-Krylov力和静水力是通过对船体瞬时湿表面压力积分获得的,同时考虑垂荡-横摇-纵摇三自由度之间的耦合作用,以及非线性横摇阻尼的影响。以国际标模C11集装箱船为研究对象,数值分析不同航速和波陡条件下的参数横摇运动规律,将计算结果与已有的试验结果进行了对比,并依据IMO提案中关于参数横摇的定量验证标准进行准确性评估,评估结果为IMO参数横摇直接稳性评估方法的制定提供了相关技术支撑。

The second generation intact stability criteria are under development by the International Maritime Organization(IMO), where parametric roll is one of the most important stability failure modes. For providing a method with high precisionand being convenient for engineering application to predict parametric roll, a 3 D time-domain panel method is used to studyparametric roll of a ship in regular waves. In this method, a hybrid method based on the Rankine source and the time-domainGreen function is applied to calculate radiation potential and diffraction potential. Radiation force and diffraction force are computed by pressure integration over the mean wetted surface, while Froude-Krylov force and hydrostatic force are calculated over the instantaneous wetted surface of the hull. At the same time, the coupling of heave, roll and pitch, and nonlinear roll damping are considered. Taking the C11 container ship as an example, roll motions in the conditions with different forward speeds and wave steepnesses are analyzed, and the numerical results are compared with existing experimental results for verification. Accuracy assessment is carried out according to quantitative validation requirements of parametric roll, which provides foundation for the development of direct stability assessment method of parametric roll.