﻿ 基于大涡模拟的泵喷推进器梢隙流场特性研究
 舰船科学技术  2001, Vol. 44 Issue (6): 95-101    DOI: 10.3404/j.issn.1672-7649.2022.06.020 PDF

1. 海军工程大学 舰船与海洋学院，湖北 武汉 430033;
2. 中国人民解放军 91697部队，山东 青岛 266000

Research on the flow field characteristic in tip gap of pump-jet propeller based on large eddy simulation
SUN Da-peng1, YE Jin-ming1, SHI Bao-yong2
1. College of Ship and Ocean , Naval University of Engineering, Wuhan 430033, China;
2. No.91697 Unit of PLA, Qingdao 266000, China
Abstract: The flow field in the small gap between the inner wall of duct and blade tip of rotor of the pump-jet propeller is the most complicate region in the whole internal flow field of the duct. In this study, a numerical simulation on flow field in the tip gap of pump-jet propeller was carried out based on large eddy simulation in order to disclose characteristic of this flow field. Moreover, a computing method for flow field characteristic in the tip gap was set up through a verification of irrelevance between the grid number and time step. The formation, transmission and diffusion processes of vortex structures in the flow field were analyzed. Additionally, effects of turbulence models and advance coefficient on the vortex structural morphology in the flow field were compared. Research conclusion can provide references to control flow field in the tip gap of pump-jet propeller.
Key words: pump-jet propeller     flow field in tip gap     large eddy simulation     mechanism analysis
0 引　言

1 数值计算方法 1.1 大涡模拟的控制方程

 $\stackrel-{\phi }\left(x\right)={\int }_{D}^{2}\phi \left({x}'\right)G\left(x,{x}'\right){\rm d}{x}',$ (1)
 $G\left(x,{x}'\right)=\left\{\begin{array}{c}1/V，({x}'\in V)，\\ 0，({x}'\notin V)。\end{array}\right.$ (2)

 $\left\{\begin{array}{l} \dfrac{\partial \rho }{\partial t}+\dfrac{\partial }{\partial {x}_{i}}\left(\rho {\bar{u}}_{i}\right)=0，\\ \dfrac{\partial }{\partial t}\left(\rho {\bar{u}}_{i}\right)+\dfrac{\partial }{\partial {x}_{j}}\left(\rho {\bar{u}}_{i}{\bar{u}}_{j}\right)=-\dfrac{\partial \bar{p}}{\partial {x}_{i}}+\dfrac{\partial }{\partial {x}_{j}}\left(\mu \dfrac{\partial {\sigma }_{ij}}{\partial {x}_{j}}\right)-\dfrac{\partial {\tau }_{ij}}{\partial {x}_{j}}。\end{array}\right.$ (3)

 ${\sigma }_{ij}=\mu \left(\dfrac{\partial {\bar{u}}_{i}}{\partial {x}_{j}}+\dfrac{\partial {\bar{u}}_{j}}{\partial {x}_{i}}\right)-\dfrac{2}{3}\mu \dfrac{\partial {\bar{u}}_{i}}{\partial {x}_{i}}{\mathrm{\delta }}_{ij} ，$ (4)
 ${\tau }_{ij}=\rho \overline{{u}_{i}{u}_{j}}-\rho {\bar{u}}_{i}{\bar{u}}_{j} 。$ (5)

1.2 几何模型和网格划分

 图 1 泵喷推进器几何模型 Fig. 1 Geometry of pump-jet propeller

 图 2 计算域划分形式 Fig. 2 The division of computational domain

 图 3 计算域整体网格及边界条件 Fig. 3 The mesh of outer domain and boundary condition

 图 4 转子域网格 Fig. 4 The mesh of rotating domain
2 数值计算方法验证 2.1 泵喷推进器水动力性能计算

 图 5 泵喷推进器敞水性能曲线 Fig. 5 The open water performance of pump-jet propeller
2.2 网格无关性验证及时间步长影响分析

3 结果分析 3.1 梢隙流场中涡结构及形成机理分析

 图 6 静止壁面边界层内流动示意图 Fig. 6 Diagrammatic drawing of flow in the boundary layer of rest wall

J=0.987工况下梢隙流场数值模拟结果进行分析，梢隙流场中的涡结构主要可以分为两部分，一部分是梢隙泄流在转子吸力面边缘处形成的梢隙泄涡，结合图7（a）和图8可知，流体在叶面与叶背之间压差力的作用下从转子压力面向径向运动，绕过梢部端面流向转子吸力面，与吸力面一侧的主流相互作用形成漩涡。可以发现梢隙泄涡最初附着在转子吸力面边缘，随着泄涡向随边方向不断发展和增强，涡结构也变得更加明显。从梢隙泄涡的发展轨迹可知，泄涡的低压中心会在吸力面边缘某一位置处脱离并进入转子通道，同时由于粘性对漩涡有扩散作用，使得梢隙泄涡在转子通道内不断发展和扩散，涡核的压力有所提高。

 图 7 梢隙流场流线图 Fig. 7 Streamline diagram of tip gap flow field

 图 8 沿叶梢弦长方向压力分布 Fig. 8 Pressure distribution along the chord length of the blade tip

 图 9 不同弦长处剖面速度矢量云图 Fig. 9 Velocity vectors nephogram of section plane in different chord length
3.2 湍流模型对梢隙流场中涡结构形态的影响

 图 10 不同湍流模型计算的涡结构形态 Fig. 10 Morphology of vortex structure calculated by different turbulent models

3.3 进速系数对梢隙流场中涡结构形态的影响

 图 11 不同进速系数下的涡结构形态 Fig. 11 Morphology of vortex structure under advance coefficient
4 结　语

1）泵喷推进器梢隙流场中的涡结构一部分是流体进入梢部间隙形成的梢部端面分离涡，另一部分是流体穿过梢部间隙流向吸力面后向内卷起形成的梢隙泄涡，同时梢部端面分离涡和梢隙泄涡会在转子尾缘后与主流相互混合并形成稳定、集中的梢涡。

2）通过对梢隙流场进行分析，揭示了梢部间隙内涡结构的形成机理，展示了梢隙流场中涡结构的生成、输运和扩散过程。

3）相较于SSTk-ω湍流模型和DES湍流模型，采用LES湍流模型进行数值模拟可以捕捉到梢隙流场中随机脱落的分离涡，且捕捉到的梢涡的延伸距离更长。其主要原因是LES直接对瞬态流动中所有超过亚网格尺度的涡进行模拟，能够获得丰富的涡结构信息。

4）随着进速系数的增加，梢隙泄涡会延后脱离转子吸力面，泄出的梢部端面分离涡的数量增加、强度增大。

 [1] 刘玉文, 徐良浩, 张国平, 等. 梢隙流动空化初生及空化形态观测研究[J]. 水动力学研究与进展(A辑) . 2017, 321061(6): 671−679. LIU Yu-wen, XU Liang-hao, ZHANG Guo-ping, et al. Observation andresearch on the cavitation inception and cavitation structure of tip leakage flow[J]. Journal of Hydrodynamics. 2017, 321061(6): 671−679. [2] 韩宝玉, 熊鹰, 刘志华. 梢涡空化CFD数值方法[J]. 哈尔滨工程大学学报, 2011, 32(6): 702-707. HAN Bao-yu, XIONG Ying, LIU Zhi-hua. Numerical study of tip vortex cavitation using CFD method[J]. Journal of Harbin Engineering University, 2011, 32(6): 702-707. [3] MOON I S, KIM K S, LEE C S. Blade tip gap low model for performance analysis of waterjet propulsors [C]//IABEM, 2002. [4] KERWIN J. A surface panel method for the hydrodynamic analysis of ducted propellers[J]. Society of Naval Architects and Marine Engineers-Transactions, 1987, 95: 93-122. [5] LEE Y T, HAH C, LOELLBACH J. Flow analyses in a single-stage propulsion pump[J]. Journal of turbomachinery, 1996, 118(2): 240-248. DOI:10.1115/1.2836631 [6] YU L, GREVE M, DRUCKENBROD M, et al. Numerical analysis of ducted propeller performance under open water test condition[J]. Journal of Marine Science and Technology, 2013, 18(3): 381-394. DOI:10.1007/s00773-013-0215-4 [7] KUSANO K, JEONG J H, YAMADA K, et al. detached eddy simulation of unsteady flow field and prediction of aerodynamic sound in a half-ducted propeller fan[C]//ASME-JSME-KSME 2011 Joint Fluids Engineering, Conference. 2011: 713−722. [8] WU H, MIORINI R L, KATZ J. Analysis of turbulence in the tip region of a waterjet pump rotor[C]// ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2010: 699−711. [9] YONGLE D, BAOWEI S, PENG W. Numerical investigation of tip clearance effects on the performance of ducted propeller[J]. International Journal of Naval Architecture and Ocean Engineering, 2015, 7(50: 795-804. [10] 王涛, 周连第. 高速旋转状态下间隙流动对主流影响的数值模拟和机理研究[C]// 全国水动力学学术会议. 2003. WANG TAO, ZHOU Lian-di. Numerical simulation and mechanism study on the influence of gap flow on mainstream in high speed rotation[C]// National Hydrodynamics Conference, 2003. [11] 鹿麟, 潘光. 泵喷推进器非定常空化性能数值模拟分析[J]. 上海交通大学学报, 2015, 49(2): 262-268. LU Lin, PAN Guang. Numerical simulation analysis of unsteady cavitation performance of a pump-jet propulsor[J]. Journal of Shanghai Jiaotong University, 2015, 49(2): 262-268. [12] 鹿麟. 泵喷推进器设计与流场特性研究[D]. 西安: 西北工业大学, 2016. LU Lin. Reasearch on design and flow field characteristic of pumpjet propulsor[D]. Xi ' an : Northwest University of Technology, 2016. [13] 鹿麟, 李强, 高跃飞. 不同叶顶间隙对泵喷推进器性能的影响[J]. 华中科技大学学报(自然科学版), 2017(8). LU Lin, LI Qiang, Gao Yue-fei. Numerical investigation of effect of different tip clearance size on the pumpjet propulsor performance[J]. Journal of Huazhong University of Science and Technology(Nature Science Edition, 2017(8).