﻿ 不同漂角下纵倾对集装箱船阻力影响的数值分析
 舰船科学技术  2023, Vol. 45 Issue (11): 46-50    DOI: 10.3404/j.issn.1672-7619.2023.11.009 PDF

Numerical study on the influence of trim on drag of container ship under different drift angles
ZHANG Yi-jiu, HAO Yong-zhi, PENG Xiao-xing, JIA Ai-peng
Marine Engineering College, Zhejiang International Marine College, Zhoushan 316021, China
Abstract: In order to study the influence of trimming state on the resistance of container ships under different drift angles, taking KCS container ships as an example, the RANS numerical method is used to study the influence of trim on the resistance of KCS ship models under different drift angles and calculate the ship resistance at the initial even keel. The numerical test results are compared with the existing data to verify the effectiveness of the numerical method. Based on this method, the ship resistance under different trimming angles at different drift angles is calculated. The results show that the pressure resistance changes significantly due to the unequal forces on both sides of the bow when the trimming angle changes at different drift angles and the optimal trimming angle of the minimum resistance of the ship changes with the drift angle.
Key words: RANS     longitudinal inclination     resistance     drift angle
0 引　言

1 数值方法 1.1 控制方程

 $\frac{{\partial \left( {\rho \overline {{u_i}} } \right)}}{{\partial {x_i}}} = 0 ，$ (1)
 $\frac{{\partial \left( {\rho {{\overline u }_i}} \right)}}{{\partial t}} + \frac{\partial }{{\partial {x_j}}}(\rho \overline {{u_i}} \overline {{u_j}} + \rho \overline {u_i'u_j'} ) = - \frac{{\partial \overline p }}{{\partial {x_i}}} + \frac{{\partial {{\overline \tau }_{ij}}}}{{\partial {x_j}}}。$ (2)

 ${\overline \tau _{ij}} = \mu \left( {\frac{{\partial {{\overline u }_i}}}{{\partial {x_j}}} + \frac{{\partial {{\overline u }_j}}}{{\partial {x_i}}}} \right)。$ (3)

 $\frac{{\partial \alpha }}{{\partial t}} + \nabla \left( {\alpha U} \right) = 0 。$ (4)

1.2 船舶模型

 图 1 KCS模型的几何形状 Fig. 1 Geometry of the KCS model

1.3 计算域、网格和边界条件

 图 2 计算领域和网格 Fig. 2 Computing domains and grids

 图 3 船舶倾斜运动示意图 Fig. 3 Diagram of ship tilting motion
2 纵倾对阻力的影响及分析 2.1 数值验证

 $p = \frac{1}{{\ln ({r_{21}})}}\left. {\left| {\ln \left| {\left. {{\varepsilon _{32}}/{\varepsilon _{21}}} \right| + q(p)} \right.} \right.} \right| ，$ (5)
 $q(p) = \ln \left( {\frac{{r_{21}^p - s}}{{r_{32}^p - s}}} \right) ，$ (6)
 $s = 1 \cdot {{\rm{sgn}}} ({\varepsilon _{32}}/{\varepsilon _{21}}) 。$ (7)

 $\phi _{ext}^{21} = (r_{21}^p{\phi _1} - {\phi _2})/(r_{21}^p - 1)。$ (8)

 $e_a^{21} = \left| {\frac{{{\phi _1} - {\phi _2}}}{{{\phi _1}}}} \right|，$ (9)
 $e_{est}^{21} = \left| {\frac{{\phi _{ext}^{21} - {\phi _1}}}{{\phi _{ext}^{21}}}} \right| ，$ (10)

 ${{GCI}}_{{\text{fine}}}^{{\text{21}}} = \frac{{1.25e_a^{21}}}{{r_{21}^p - 1}}。$ (11)

2.2 不同漂角下纵倾对船舶阻力影响

 图 4 自由下蹲和约束下蹲状态对比 Fig. 4 Comparison of free squats and constrained squats
 ${D_t} = \frac{{{R_{tn}} - {R_{t0}}}}{{{R_{t0}}}}\times 100\text% 。$ (12)

 图 5 不同漂角下纵倾对船舶阻力影响 Fig. 5 Influence of trim on ship drag under different drift angles

2.3 阻力变化分析

 ${D_f} = \frac{{{R_{fn}} - {R_{f0}}}}{{{R_{f0}}}}\times 100\text% ，$ (13)
 ${D_p} = \frac{{{R_{pn}} - {R_{p0}}}}{{{R_{p0}}}}\times 100\text% 。$ (14)

 图 6 摩擦阻力变化率 Fig. 6 Rate of change of friction resistance

 图 7 剩余阻力变化率 Fig. 7 Rate of change of residual resistance

 图 8 兴波云图 Fig. 8 Wave-making cloud
3 结　语

1） 集装箱船在有漂角的情况下直航时，纵倾对船舶阻力影响规律不一致；

2） 对于较大型船舶在预测阻力时，船舶下蹲变化不可忽略；

3） 比较不同纵倾状态总阻力可知，对于集装箱船在满载吃水状态下，尾倾时阻力增加；

4） 通过不同阻力成分比较可知，该集装箱船在纵倾改变时，剩余阻力变化较大，为阻力变化的主导因素。

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