﻿ 半潜式海洋平台阻力预报数值模拟分析
 舰船科学技术  2022, Vol. 44 Issue (18): 106-110    DOI: 10.3404/j.issn.1672-7649.2022.18.021 PDF

1. 中海油研究总院有限责任公司，北京 100027;
2. 北京迪玛尔海洋技术有限公司，北京 100085

Numerical simulation analysis of resistance prediction of semi submersible offshore platform
YI Cong1, SONG Chun-hui1, LI Gang1, CHEN Yong-jun2, LAI Min2
1. CNOOC Research Institute Co., Ltd., Beijing 100027, China;
2. Beijing Dimar Marine Technology Co., Ltd., Beijing 100085, China
Abstract: Based on STAR-CCM +, the three-dimensional numerical simulation of Semi-submerged platform is carried out by using turbulence model. The offshore platform and pressure distribution are calculated, and the algorithm is verified by comparing with the experimental results. On this basis, the variation laws of platform resistance and surface pressure under different inflow directions and velocities are analyzed. The results show that the platform resistance is greatly affected by the shielding effect and the area of the upstream surface. Under the same inflow velocity, the platform resistance in different directions increases with the inflow angle. Under the same inflow direction, the platform resistance increases with the increase of inflow velocity.
Key words: semi-submerged platform     resistance prediction     turbulence model     masking effect
0 引　言

1 数值方法

1.1 控制方程

 $\frac{{\partial \rho }}{{\partial t}} + \frac{\partial }{{\partial {x_i}}}\left( {\rho {u_i}} \right) = 0，$ (1)
 $\begin{gathered} \frac{\partial }{{\partial t}}\left( {\rho {u_i}} \right) + \frac{\partial }{{\partial {x_i}}}\left( {\rho {u_i}{u_j}} \right) = - \frac{{\partial p}}{{\partial {x_i}}} + \frac{\partial }{{\partial {x_j}}} \\ \left[ {\mu \left( {\frac{{\partial {u_i}}}{{\partial {x_j}}} + \frac{{\partial {u_j}}}{{\partial {x_i}}} - \frac{2}{3}{\delta _{ij}}\frac{{\partial {u_l}}}{{\partial {x_l}}}} \right)} \right] + \frac{\partial }{{\partial {x_j}}}\left( { - \rho \overline {{{u'}_i}{{u'}_j}} } \right)。\\ \end{gathered}$ (2)

1.2 湍流模型

CFD软件中可选择的湍流模型有 $k - \varepsilon$ 模型， $k - \omega$ 模型，RNG $k - \varepsilon$ 模型等，本文采用 $k - \varepsilon$ 湍流模型。

 $\rho \frac{{\partial k}}{{\partial t}} = \frac{\partial }{{\partial {x_i}}}\left[ {\left( {\mu + \frac{{{\mu _t}}}{{{\sigma _k}}}} \right)\frac{{\partial k}}{{\partial {x_i}}}} \right] + {G_k} + {G_b} - \rho \varepsilon - {Y_M}。$ (3)

 $\rho \frac{{\partial \varepsilon }}{{\partial t}} = \frac{\partial }{{\partial {x_i}}}\left[ {\left( {\mu + \frac{{{\mu _t}}}{{{\sigma _k}}}} \right)\frac{{\partial \varepsilon }}{{\partial {x_i}}}} \right] + {c_{1\varepsilon }}\frac{\varepsilon }{k} + {G_k} + {G_{3\varepsilon }}{G_b} - {C_{2\varepsilon }}\rho \frac{{{\varepsilon ^2}}}{k}。$ (4)

 ${\mu _t} = \frac{{{c_\mu }\rho {k^2}}}{\varepsilon }。$ (5)

2 计算模型与边界条件 2.1 平台模型

 图 1 半潜式平台水下部分示意图 Fig. 1 Schematic diagram of underwater part of semi submersible platform

2.2 计算域和边界条件

 图 2 边界条件 Fig. 2 Boundary conditions
2.3 网格划分

 图 3 网格区域网格划分 Fig. 3 Grid division of grid area

 图 4 半潜式海洋平台网格划分 Fig. 4 Grid division of semi submersible offshore platform
3 计算结果及分析 3.1 模拟精度分析

 图 5 不同流向角度下阻力变化曲线对比图 Fig. 5 Comparison of resistance variation curves under different flow direction angles

 图 6 误差范围 Fig. 6 Error range
3.2 不同来流方向平台表面压力分析

 图 7 不同流向角度压力分布图 Fig. 7 Pressure distribution at different flow directions and angles
3.3 不同来流方向下的流载荷分析

 图 8 不同流向角度下阻力变化曲线 Fig. 8 Resistance variation curve under direction angles

y方向阻力变化规律近似正弦函数，阻力在流向角度0°～60°内增长速度较快，在流向角度60°～90°内增长速度较慢，当流向角度为60°时，y方向阻力最大为50.38 N。z方向阻力变化规律关于流向角度180°具有一定的对称性，且均为负压，这是由于平台在一定流向角度上迎流面积相似从而导致阻力变化曲线对称。当流向角度为0°～60°及90°～165°时，阻力随流向角度的增加而增加，当流向角度为60°～90°及165°～180°时，阻力随流向角度的增加而减小。

3.4 不同来流速度下的阻力分析

 图 9 不同来流速度x方向阻力 Fig. 9 x direction at different inflow speeds

 图 11 不同来流速度z方向阻力 Fig. 11 x direction at different inflow speeds

 图 12 不同来流速度阻力最大值 Fig. 12 Max resistance at different velocities

 图 10 不同来流速度y方向阻力 Fig. 10 ydirection at different inflow speeds
4 结　语

1）本文基于CFD数值模拟方法进行的数值分析有效，对半潜式海洋平台的阻力分析具有一定的参考价值；

2） $k - \varepsilon$ 湍流模型对半潜式海洋平台阻力的预报偏差在2.6%以内；

3）半潜式平台所受阻力受“遮蔽”效应和迎流面面积的影响；

4）相同来流速度下，各方位阻力随流向角度增大规律各不相同；

5）相同流向角度下，阻力随着来流速度的增大而增大。

 [1] MATAUMTO F T, WATAI R A, SIMOA A N. Wave run-up and air gap prediction for a large-volume semi-submersible platform[C]// ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering, 2010. [2] LI B B, OU J P and TENG B. The full coupled effects of hull, mooring and risers model in time domain based on an innovative deep draft multi-spar[J]. China Ocean Engineering, 2010, 24(2). [3] 范亚丽, 匡晓峰, 方田, 等. 半潜式支持平台恶劣海况下的运动性能试验研究[J]. 船舶工程, 2021, 43(2): 134-140. Fan Yali, Kuang Xiaofeng, Fang Tian, et al. Experimental Study on the Motion Performance of Semi-submersible Support Platform in Severe Sea Conditions[J]. Ship engineering, 2021, 43(2): 134-140. [4] 张明霞, 卢鹏程, 韩兵兵, 等. 基于STAR-CCM+平台和OCIMF方法的FPSO流载荷计算与分析[J]. 中国海洋平台, 2020, 35(4): 49-55. Zhang Mingxia, Lu Pengcheng, Han Bingbing, et al.. Calculation and analysis of FPSO flow load based on STAR-CCM+ platform and OCIMF method[J]. China Ocean Platform, 2020, 35(4): 49-55. [5] 董斌, 陈凯旋, 聂焱, 等. 半潜式平台横撑波浪抨击载荷下结构强度分析[J]. 舰船科学技术, 2019, 41(1): 80-84. Dong Bin, Chen Kaixuan, Nie Yan, etc.. Structural strength analysis of cross brace of semi-submersible platform under wave attack load[J]. Ship Science and Technology, 2019, 41(1): 80-84. DOI:10.3404/j.issn.1672-7649.2019.01.015 [6] 袁洪涛, 陈正豪, 陈刚, 等. 风浪流联合作用下油气资源开发保障平台系泊系统响应的计算分析[J]. 船海工程, 2019, 48(2): 159-162+166. Yuan Hongtao, Chen Zhenghao, Chen Gang, etc.. Calculation and analysis of mooring system response of oil and gas resources development support platform under wind and wave combined action[J]. ship & Ocean Engineering, 2019, 48(2): 159-162+166. DOI:10.3963/j.issn.1671-7953.2019.02.041 [7] 陈江华, 裴春, 尼鹏, 等. 风浪流联合作用下移动式水上作业平台的施工稳定性[J]. 船舶工程, 2021, 43(7): 147-152. Chen Jianghua, Pei Chun, Ni Peng, etc.. Construction stability of mobile offshore platform under the combined action of wind and waves[J]. Ship Engineering, 2021, 43(7): 147-152. [8] 安康. 半潜式海洋平台撑杆在拖航工况下的波浪砰击载荷预报[D]. 镇江: 江苏科技大学, 2020. [9] 谷家扬, 杨琛, 刘为民, 等. 基于CFD技术的半潜式钻井服务支持平台风荷载预报[J]. 中国海洋平台, 2015, 30(6): 42-48. Gu Jiayang, Yang Chen, Liu Weimin, et al.. Wind load forecast of semi-submersible drilling service platform based on CFD technology[J]. China Ocean Platform, 2015, 30(6): 42-48. DOI:10.3969/j.issn.1001-4500.2015.06.008 [10] 彭超, 冯光, 郑文涛, 等. 半潜式钻井平台风载荷CFD预报[J]. 船舶工程, 2020, 42(S1): 420-423.