﻿ 水下航行器内孤立波载荷形成机理数值模拟研究
 舰船科学技术  2022, Vol. 44 Issue (1): 91-96    DOI: 10.3404/j.issn.1672-7649.2022.01.018 PDF

1. 深海技术科学太湖实验室，江苏 无锡 214082;
2. 中国船舶科学研究中心船舶振动噪声重点实验室，江苏 无锡 214082

Numerical simulation study on the formation mechanism of internal solitary waves loads acting on a underwater vehicle
YAO Zhi-chong1, LIU Chuan-qi1, LIU Le1, GAO De-bao2
1. Taihu Laboratory on Deep Sea Technology and Science, Wuxi 214082, China;
2. National Key Laboratory on Ship Vibration and Noise, China Ship Scientific Research Center, Wuxi 214082, China
Abstract: Clarifying the mechanism of the formation of internal solitary wave loads on underwater vehicles is the basis and prerequisite for the analysis of the impact of internal solitary waves on navigation performance and control research. In this paper, numerical simulations are used to analyze the processes of the hydrodynamic generated by flow filed and statics generated by density difference processes acting on the model under three scenarios: above the wave surface, across the wave surface and below the wave surface, and to compare the differences of longitudinal force, vertical force and pitching moment at different depths. The results show the change of fluid density where the model is located plays a decisive role in the case of crossing the wave surface, and the vertical force is one order of magnitude larger than the longitudinal force; the head and tail buoyancy forces are unbalanced, producing extreme and minimal values of the pitching moment, respectively. when the model is always located above or below the interface, the hydrodynamic is also significantly changed by the internal solitary wave flow field.
Key words: underwater vehicle     internal solitary waves     loads     numerical simulation
0 引　言

1 数值模拟方法 1.1 内孤立波理论

 图 1 两层流体中内孤立波作用示意图 Fig. 1 Diagram of the action of internal solitary wave in two layer fluids

 ${\mathrm{\eta }}_{{t}}+\left({{c}}_{0}+{{c}}_{1}\mathrm{\eta }+{{c}}_{3}{\mathrm{\eta }}^{2}\right){\mathrm{\eta }}_{\mathrm{x}}+{{c}}_{2}{\mathrm{\eta }}_{\mathrm{x}\mathrm{x}\mathrm{x}}=0 。$ (1)

eKdV方程有如下内孤立波解：

 ${\eta }\left({x},{t}\right)=\frac{{a}}{{B}+\left(1-{B}\right){{\rm{c}}}{{\rm{o}}}{{\rm{s}}}{{{\rm{h}}}}^{2}\left[{\lambda }\left({x}-{c}{t}\right)\right]}。$ (2)

1.2 边界条件及计算设置

 ${{U}}_{1}=-{c}\frac{{\eta }}{{{h}}_{1}-{\eta }}；$ (3)
 ${{U}}_{2}={c}\frac{{\eta }}{{{h}}_{2}-{\eta }} 。$ (4)

1.3 研究对象

 图 2 Suboff模型 Fig. 2 Model of Suboff
1.4 试验验证

 图 3 模型受力随时间变化关系曲线 Fig. 3 Time-dependent curves of the forces on model

2 数值模拟结果及分析 2.1 数值模拟工况

 ${{C}}_{{D}}=\frac{{{F}}_{{x}}}{{{\rho }}_{0}{{g}}^{{、}}{A}{D}} \text{，} {{C}}_{{L}}=\frac{{{F}}_{{z}}}{{{\rho }}_{0}{{g}}^{{、}}{A}{D}} \text{，} {{C}}_{{M}}=\frac{{M}}{{{\rho }}_{0}{{g}}^{{、}}{A}{D}{L}} 。$ (5)

2.2 内孤立波模拟结果

 图 4 内孤立波波形及传播演化情况 Fig. 4 Waveform of internal solitary wave and propagation evolution

 图 5 内孤立波诱导的流场特征 Fig. 5 The characteristic of flow filed induced by internal solitary wave
2.3 内孤立波作用过程分析

 图 6 模型位于分层界面上方10 cm工况的受力曲线 Fig. 6 Forces curve of the model located 10 cm above the interface

 图 7 模型位于界面下方10 cm遭遇内孤立波过程图 Fig. 7 Diagram of the process of the model located 10 cm below the interface encountering internal solitary wave

 图 8 模型位于界面下方10 cm工况的受力曲线 Fig. 8 Forces curve of the model located 10 cm below the interface

 图 9 模型位于界面下方30 cm工况的受力曲线 Fig. 9 Forces curve of the model located 30 cm below the interface
2.4 不同潜深时作用力特性分析

 图 10 潜深不同时模型受力曲线 Fig. 10 Forces curve of the model for different depths

2.5 不同波幅时作用力特性分析

 图 11 波幅不同时模型受力曲线 Fig. 11 Forces curve of the model for different wave amplitudes

3 结　语

1）有模型穿进、穿出波面的情况下，模型所处的流体密度变化，起了决定性作用，垂向力比纵向力大一个量级；对于俯仰力矩，在穿进、穿出波面的情况时，艏艉浮力不平衡，分别产生了俯仰力矩的极大值和极小值；模型位于分层界面上方或始终位于内孤立波波面下方时，受内孤立波流场的影响，其水动力性能也产生了明显的变化。

2）潜深不同时，受波面上方和下方的流场方向相反影响，模型位于分层界面上方与下方纵向力的变化规律相反；受有无密度差静力作用影响，穿越波面的工况与始终位于分层界面上方或下方的工况垂向力变化规律明显不同。

3）不同波幅时，纵向力、垂向力和俯仰力矩随时间变化规律基本相同，极大/小值都随波幅增加大而增大，波幅大小不影响内孤立波载荷的形成机理；

 [1] BOLE J B, EBBESMEYER C C, ROMEA R D. Soliton curents in the South China Sea : measurements and theoretcal modeling[C]//The 26th Annual OTC in Houston, Texas, U. S. A. , 2-5 May, 1994: 387−396. [2] EBBESMEYER C C, COOMES C A, et al. New observations on internal waves(solitons) in the South China Sea using an acoustic Doopler current proflier[C]//Marine Technology Society 91 Proceedings, New Orleans, 1991: 165−175. [3] 沈国光, 叶春生. 内波孤立子的非波导荷载计算[J], 天津大学学报. 2005, 38(12): 1046−1050. [4] CAI S Q, LONG X M, GAN Z J. A method to estimate the forces exerted by internal solitons on cylinder piles[J]. Ocean Engineering, 2003, 30: 673−689. [5] 付东明, 尤云祥, 李巍. 两层流体中内孤立波与潜体相互作用的数值模拟[J]. 海洋工程, 2009, 27(3): 38-44. DOI:10.3969/j.issn.1005-9865.2009.03.006 [6] 陈杰, 尤云祥, 刘晓东, 等. 内孤立波与有航速潜体相互作用数值模拟[J]. 水动力学研究与进展, 2010, 25(3): 343-351. [7] 王旭. 内孤立波与深海浮式结构物相互作用特性研究[D]. 上海: 上海交通大学, 2015. [8] WEI Gang, DU Hui, XU Xiao-hui, et al. Experimental investigation of the generation of large amplitude internal solitary wave and its interaction with a submerged slender body[J]. Physics, Mechanics & Astronomy, 2014, 57(2): 201-310. [9] DU Hui, WEI Gang, GU Meng-meng, et al. Experimental investigation of the load exerted by nonstationary internal solitary waves on a submerged slender body over a slope[J]. Applied Ocean Research, 2016(59): 216-223. [10] 关晖, 魏岗, 杜辉. 内孤立波与潜艇相互作用的水动力学特性[J]. 解放军理工大学学报, 2012, 13(5): 577-582. [11] CHOI W, CAMASSA R. Fully nonlinear internal waves in a two-fluid system[J]. Journal Fluid Mech, 1999, 396: 1−36