﻿ 内倾船型在横风横浪状态下的倾覆概率评估方法
 舰船科学技术  2020, Vol. 42 Issue (10): 23-25    DOI: 10.3404/j.issn.1672-7649.2020.10.005 PDF

A capsizing probability assessment method for an inward - leaning ship under cross - wind and waves
JIA Ru-cun
School of Law, Shanghai Maritime University, Shanghai 200000, China
Abstract: The evaluation of the capsizing probability of the inner capsized ship can effectively prevent the capsizing of the inner capsized ship and improve the stability of the inner capsized ship. In this paper, a method is designed to evaluate the capsizing probability of the inner capsized ship under the condition of crosswind and wave. Firstly, the motion state equation of the ship is designed, and four different coordinate systems are introduced to describe it in detail, and the wind tilt moment and wave moment are calculated, combined with the equation of motion state to quantify the rolling motion of the ship, determine the capsizing conditions of the ship, use the Monte Carlo method to get the statistical estimate value of capsizing probability, calculate the confidence interval, determine the value of width and narrowness, and complete the capsizing probability evaluation of the internal capsizing ship in the state of cross wind and cross wave. In order to verify the accuracy of the method, a simulation experiment is designed in the water tank. The experimental results show that under different initial stability height and wind speed, the overturning probability of the designed method is closer to the real results.
Key words: inclined-ship type     coverage ratio     cross wind and waves     wind tilt moment     wave moment
0 引　言

1 内倾船型在横风横浪状态下的倾覆概率评估 1.1 量化分析船舶的横摇运动

 图 1 坐标系示意图 Fig. 1 Coordinate system diagram

 ${M_{\text{风}}}{\rm{ = }}0.5 \times {\rho _{air}}{C_m}U_w^2{A_L}{H_c}\text{。}$ (1)

 ${M_{\text{浪}}}{\rm{ = }}W \cdot h \cdot \gamma \text{。}$ (2)

 $\left( {{I_x} + \delta {I_x}} \right) + {B_L} + {B_N} + \Delta C{\rm{ = }}{M_{\text{浪}}} + {M_{\text{风}}}\text{。}$ (3)

1.2 评估倾覆概率

 $P_C^*({T_r}) = \frac{{{N_C}}}{{{N_r}}}\text{，}$ (4)

 $\begin{split} & {P_t} = \frac{{{P^*} + \frac{{K_\beta ^2}}{{2{N_r}}} - {K_\beta }\sqrt {\frac{{{P^*}(1 - {P^*})}}{{{N_r}}} + \frac{{K_\beta ^2}}{{4N_r^2}}} }}{{1 + \frac{{K_\beta ^2}}{{{N_r}}}}} \text{，}\\ & {P_u} = \frac{{{P^*} + \frac{{K_\beta ^2}}{{2{N_r}}} + {K_\beta }\sqrt {\frac{{{P^*}(1 - {P^*})}}{{{N_r}}} + \frac{{K_\beta ^2}}{{4N_r^2}}} }}{{1 + \frac{{K_\beta ^2}}{{{N_r}}}}} \text{，} \end{split}$ (5)

 $P = ({P_t} - {P_u})\frac{{{N_C}}}{{{N_r}}}\text{。}$ (6)
2 实　验 2.1 实验准备

 图 2 实验耐波性水池 Fig. 2 Experimental seakeeping tank

 ${S_{wave}}\left( {{\omega _i}} \right) = \frac{A}{{\omega _i^5}}\exp \left[ { - \frac{B}{{\omega _i^4}}} \right]\text{。}$ (7)

2.2 实验结果比较与分析

 图 3 两种方法静水中横摇衰减曲线对比图 Fig. 3 Comparison of rolling attenuation curves of two methods in still water

 图 4 两种方法在不同GM下的倾覆概率评估结果 Fig. 4 Capsizing probability assessment results of the two methods under different GM

 图 5 两种方法在不同风速下的倾覆概率评估结果 Fig. 5 Capsizing probability assessment results of the two methods under different wind speeds
3 结　语

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