﻿ 窄裂纹通道流动特性数值计算研究
 舰船科学技术  2018, Vol. 40 Issue (8): 110-113 PDF

1. 海装广州局，广东 广州 510310;
2. 武汉第二船舶设计研究所热能动力技术重点实验室，湖北 武汉 430205

Numerical research of flow characteristics in narrow crack flow channel
ZHANG De-kui1, LI Shao-dan2, LIN Yuan-sheng2
1. Navy Equipment Department Guangzhou Bureau, Guangzhou 510310, China;
2. Key Laboratory on Thermal Energy and Power, Wuhan Second Ship Design and Research Institute, Wuhan 430205, China
Abstract: The leak rate predication of the pipe crack is the foundation of the leak-before-break (LBB) technology application. The fluid flow characteristics are crucial for the calculation process of the leak rate predication. The narrow crack flow channel is modeled and parameterized by the numerical calculation technique. And the effect of the crack-morphology parameters on the fluid flow characteristics is studied by the computational fluid dynamics (CFD) analysis. The research results show the flow field and the turbulence kinetic energy distribution is relation to the ratio of the global roughness and the crack opening distance (COD). Furthermore, the friction coefficient will increase firstly and then decreased with the increase of the ratio under same Reynolds number.
Key words: narrow crack flow channel     leak rate     flow characteristics     numerical calculation
0 引　言

1 计算模型及网格

 图 1 裂纹几何形态建模 Fig. 1 Geometric shape modeling of crack

 $\delta = h\sin \left( {\frac{\alpha }{2}} \right)\text{，}$ (1)
 ${L_s} = {\mu _g}\tan \left( {\frac{\alpha }{2}} \right)\text{。}$ (2)

 图 2 流道网格划分示意 Fig. 2 Shetch of the flow path meshing

2 计算结果及分析 2.1 流场分析

 图 3 裂纹流道内速度分布 Fig. 3 The velocity in the crack flow path
2.2 湍流特性分析

 图 4 裂纹流道内湍流动能分布 Fig. 4 The kinetic energy in the crack flow path
2.3 阻力特性分析

 $f = \frac{{2\Delta {P_2}{D_H}}}{{L{\rho _f}u_f^2}}\text{。}$ (3)

 图 5 流道压降示意图 Fig. 5 Schematic diagram of flow pressure drop

 图 6 不同雷诺数下的阻力系数变化 Fig. 6 The resistance coefficient at different Reynolds numbers

 图 7 对阻力系数的影响 Fig. 7 Effect of δ/μg on resistance coefficient
3 结　语

1）裂纹张开位移和宏观粗糙度的比值（δ/μg）会影响流场和湍流动能分布特性，当δ/μg较大时，裂纹流道接近于直管道而拐弯的作用与表面粗糙度类似，当δ/μg较小时，裂纹流道内流动特性接近于有众多拐弯的直管道，其他情况则介于上述2种情况之间。

2）受裂纹流道内流场和湍流动能分布特性的影响，裂纹流道内拐弯对于阻力系数的增强作用在δ/μg较小时比较弱，随着δ/μg的增加越来越强，但当δ/μg增加到一定程度之后拐弯对于阻力系数的增强作用会再次减弱。

 [1] 乔红威, 刘志伟, 李琦, 李锡华. LBB裂纹稳定性分析方法研究[J]. 原子能科学技术, 2013, 47(11): 2108–2113. [2] Yann Kayser, Stephane Marie, Christophe Poussard, Christine Delaval. Leak Before Break procedure: Recent modification of RCC-MR A16 appendix and proposed improvements[J]. International Journal of Pressure Vessels and Piping, 2008, 85: 681–693. [3] Electric Power Research Institute, EPRI NP-3596-SR[R]. PICEP: Pipe Crack Evaluation Program (Revision 1), Revision 1, 1987 [4] PAUL D D, Ahmad J, Scott P M, et al. Evaluation and refinement of leak-rate estimation models, NUREG/CR-5128[R]. US: NRC, 1994. [5] 章静, 乔红威, 李朋州, 巫英伟, 田文喜, 秋穗正, 苏光辉. 管道贯穿裂纹泄漏率预测[J]. 原子能科学技术, 2015, 49(4): 660–666. [6] 吴万军, 谢海, 兰斌, 黄旋, 叶献辉. 管道裂纹泄漏率计算软件开发[J]. 核动力工程, 2015, 36(4): 65–68. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-NLSI201409002123.htm [7] 殷海峰, 梁兵兵, 徐宁. 管道泄漏率计算模型研究和程序开发[J]. 核技术, 2013, 36(4): 1–4. http://www.cqvip.com/QK/90373X/201504/664507574.html