﻿ 复杂水流环境下系泊船的水动力特性研究
 舰船科学技术  2022, Vol. 44 Issue (1): 1-6    DOI: 10.3404/j.issn.1672-7649.2022.01.001 PDF

1. 浙江省交通规划设计研究院有限公司 水运设计院，浙江杭州 310000;
2. 中国海洋大学 工程学院，山东 青岛 266000

Research on hydrodynamic forces of mooring ship in complex flow environment
LIU Hong-jie1, ZHANG Bo2, LOU Wan-li1, YAO Hui-lan2, LIU Yong2
1. Zhejiang Provincial Institute of Communications Planning, Design and Research Co., Ltd., Water Transportation Designing Institute, Hangzhou 31000, China;
2. Ocean University of China, College of Engineering, Qingdao 266000, China
Abstract: In order to study the hydrodynamic characteristics of moored ship under complex flow conditions of deep-water wharf, the transient numerical simulation of viscous flow field of moored ship model was carried out with STAR-CCM +. The flow force was obtained by solving RANS equation and realizable k - ε turbulence model. Under the action of steady flow without wave, the attitude of the moored ship remains stable at last, so the model can be simplified by using the fixed ship instead of the moored ship. Based on the research of grid independence and rationality of numerical model, the hydrodynamic forces of ships under different flow velocity, different flow direction angle and the flow direction changing along the water depth are predicted, and the change rules of longitudinal force, transverse force and yaw moment of moored ships under different flow conditions are discussed. The research results can provide a reference for the mooring ship′s cable layout and related engineering design in complex flow environment.
Key words: deep water wharf     complex flow     ship hydrodynamic     numerical simulation     overset mesh
0 引　言

Zhang等[1]试验测量了不同方向水流作用下，模型船所受顺流和与水流垂直方向的作用力，并与经验公式进行了对比。张怀新等[2]基于N-S方程，研究了船体的横摇阻尼问题，数值模拟了船体二维横剖面在横摇时的粘性流场，发现横摇阻尼中的压力成分大于剪切应力成分。邹志利等[3]讨论了不同水位和不同风浪流夹角对系缆力和碰撞力的影响。Xiang等[4]通过求解系泊方程研究了波浪、水流、风等外荷载对系泊缆绳张力的影响，并利用试验结果对计算结果进行了验证。Varyami等[5]考虑船舶航行所产生的波浪和水流对系泊船的影响，并与已有的试验与理论结果进行了对比。胡毅等[6]应用多体水动力学软件AQWA，研究了在风、浪、流联合载荷作用下大型LNG船码头系泊时的运动响应，得到了LNG船码头系泊时的运动响应和系缆绳所受拉力。嵇春艳等[7]利用水动力软件AQWA研究了不同浪向角对码头系泊船舶运动响应幅值算子和一阶波激力的影响，并对系泊系统进行了优化。李焱等[8]开展了不同流速和流向角条件下系泊船的物理模型试验，得到典型工况下船舶系泊安全的水流强度限制值。

1 数值模拟方法 1.1 研究对象及工况

 图 1 KCS船模型图 Fig. 1 KCS ship model diagram

 ${C_x} = \frac{{{F_x}}}{{0.5\rho {U^2}A}} {\text，}$ (1)
 ${C_y} = \frac{{{F_y}}}{{0.5\rho {U^2}A}}{\text，}$ (2)
 ${C_N} = \frac{N}{{0.5\rho {U^2}A{L_{pp}}}}{\text。}$ (3)

1.2 计算域及边界条件

 图 2 计算域及边界条件 Fig. 2 Computational domain and boundary conditions
1.3 网格划分

 图 3 z = 0 m，β = 45°时网格示意图 Fig. 3 Mesh when z = 0 m，β = 45°

 图 4 船体周围及自由面网格加密示意图 Fig. 4 Mesh refinement around hull and free surface
1.4 控制方程

 $\frac{{\partial \rho }}{{\partial t}} + \frac{{\partial \left( {\rho {u_i}} \right)}}{{\partial {x_i}}} = 0{\text，}\quad {i = 1,2,3} {\text，}$ (4)
 $\begin{split} \rho \frac{{\partial {u_i}}}{{\partial t}} + \rho {u_j}\frac{{\partial {u_i}}}{{\partial {x_j}}} =& - \frac{{\partial p}}{{\partial {x_j}}} + \frac{\partial }{{\partial {x_j}}}\left( {\mu \frac{{\partial {u_i}}}{{\partial {x_j}}} - \rho \overline {u_i'u_j'} } \right){\text，}\\ & {i,j = 1,2,3} {\text。} \end{split}$ (5)

2 数值方法验证 2.1 网格独立性

2.2 合理性验证

 $\quad {C_{f1}} = \frac{{0.075}}{{{{(\lg {Re} - 2)}^2}}}{\text，}\quad {\text{ITTC}} - 1957{\text，}$ (6)
 $\frac{{0.242}}{{\sqrt {{C_{f2}}} }} = \lg ({Re} - {C_{f2}}){\text，}\quad 1947 - {\text{ATTC}}{\text。}$ (7)

 图 5 船舶纵向受力系数及其摩擦分量系数与经验公式对比 Fig. 5 Comparison of ship longitudinal force coefficient and friction component coefficient with empirical formula
3 数值结果与讨论 3.1 不同流向下系泊船水动力分析

 图 6 不同傅汝德数下船舶首摇力矩系数随流向角度的变化 Fig. 6 Variation of ship yaw moment coefficient with flow direction angle under different Froude numbers

 图 7 不同傅汝德数下船舶横向力系数随流向角度变化 Fig. 7 Variation of ship lateral force coefficient with flow direction angle under different Froude numbers

 图 8 不同傅汝德数下船舶纵向力系数随流向角度变化 Fig. 8 Variation of ship longitudinal force coefficient with flow direction angle under different Froude numbers
3.2 不同流速下系泊船水动力分析

 图 9 不同流向角度下船舶首摇力矩系数随傅汝德数的变化 Fig. 9 Variation of ship yaw moment coefficient with Froude number under different flow direction angles

 图 10 不同流向角度下船舶横向力系数随傅汝德数的变化 Fig. 10 Variation of ship lateral force coefficient with Froude number under different flow direction angles

 图 11 不同流向角度下船舶纵向力系数随傅汝德数的变化 Fig. 11 Variation of ship longitudinal force coefficient with Froude number under different flow direction angles
3.3 复杂流态下系泊船水动力分析

 图 12 复杂流态下船舶水动力系数变化 Fig. 12 Variation of ship hydrodynamic coefficient under complex flow

4 结　语

1）对于水流不同流向角度工况，系泊船所受首摇力矩系数在β = 45°时达到最大值，横向力系数随着流向角度的增大而逐渐增大，纵向力系数的变化规律较为复杂。

2）对于水流不同流速工况，系泊船的水动力特性系数变化不明显，首摇力矩系数和横向力系数随着流速的增大变化趋势较为平缓；纵向力系数在较小流向角度时随流速增加先减小后逐渐平缓，在流向角度较大时，纵向力系数随着流速的增加先减小后增大。

3）对于复杂流态，水流流向沿船舶吃水由0°变化到90°时，水流对船体侧面作用较为明显，船体横向受力系数远大于纵向受力系数，在实际工程中应当注意；水流流向沿船舶吃水由0°变化到90°时，水流对船体侧面作用较弱，体现在船舶横向力系数远小于前者工况。

4）对于本文所设定的复杂流态工况，船舶水动力系数会与某一流向角度工况相似。因此在类似的实际工程中，可以参照相似的流向角度进行参考和设计。

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