﻿ 基于流道倾角对喷水推进泵流道性能的影响研究
 舰船科学技术  2017, Vol. 39 Issue (9): 49-53 PDF

1. 江苏海事职业技术学院 轮机工程学院, 江苏 南京 211170;
2. 渤海造船厂集团有限公司，辽宁 葫芦岛 125004

Research on the influence of waterjet duct performance based on inclination of waterjet duct
LI Chen1, SHU Xiao-hua2, ZHAO Chun-sheng1
1. Jiangsu Maritime Institute, Marine Engineering institute, Nanjing 211170, China;
2. Bohai Shipyard Co. Ltd., Huludao 125004, China
Abstract: Four different inclination waterjet duct of an elliptic inlet are designed by the parametric method, and the flow field and performance are simulated by using the three-dimensional Reynolds averaged N-S equation and S-A turbulence model. The flow field in different inclination waterjet duct is analyzed from discharge uniformity of the duct, flow separation aspects with inlet velocity ratio unchanged, so that the design basis of the inclination waterjet duct is provided. The calculation results show that the inclination of waterjet duct have great influence on the flow field and hydraulic performance. Under the condition of setting into the inlet velocity ratio, with the increase of the inclination angle of waterjet duct, the flow field of waterjet duct is more uniformity, the cavitation phenomenon of the duct is more likely to occur, and when the inclination angle of waterjet duct attain 47°, flow field characteristics of waterjet duct at the design condition is the worst.
Key words: waterjet     duct     numerical simulation     flow field analysis
0 引　言

1 喷水推进轴流泵模型和数值方法 1.1 控制方程与湍流模型

 $\frac{{\partial {u_a}}}{{\partial {x_a}}} = 0\text{，}$ (1)

 $\rho \frac{{\partial u}}{{\partial t}} + \rho \overline {{u_b}} \frac{{\partial \overline {{u_a}} }}{{\partial {x_b}}} = \overline {{F_a}} - \frac{{\partial \bar P}}{{\partial {x_a}}} + \frac{\partial }{{\partial {x_b}}}\mu \frac{{\partial \overline {{u_a}} }}{{\partial {x_b}}} - \rho \overline {{{u'}_a}{{u'}_b}}\text{。}$ (2)

 $\begin{split}& \displaystyle\frac{\partial }{{\partial t}}\rho k + \frac{\partial }{{\partial {x_a}}}\rho k{u_a} = \frac{\partial }{{\partial {x_b}}}\left[ {{\alpha _k}{\mu _i}\frac{{\partial k}}{{\partial {x_b}}}} \right] + \\& {G_k} + {G_j} - \rho \varepsilon - {Y_M} + {S_k}\text{，} \end{split}$ (3)
 $\begin{split}& \displaystyle\frac{\partial }{{\partial t}}\rho \varepsilon + \frac{\partial }{{\partial {x_a}}}\rho \varepsilon {u_a} = \frac{\partial }{{\partial {x_b}}}\left[ {{\alpha _\varepsilon }{\mu _i}\frac{{\partial \varepsilon }}{{\partial {x_b}}}} \right] + \\& {C_{1\varepsilon }}\frac{\varepsilon }{k}\left( {{G_k} + {C_{3\varepsilon }}{G_b}} \right) - {C_{2\varepsilon }}\rho \frac{{{\varepsilon ^2}}}{k} - {R_\varepsilon } + {S_\varepsilon }\text{。} \end{split}$ (4)

1.2 物理模型和网格划分

 图 1 流道三维模型 Fig. 1 Three-dimensional model of duct
1.3 边界条件

2 网格无关性验证

 图 2 效率-网格数曲线 Fig. 2 Efficiency vs grid number

 图 3 扬程-网格数曲线 Fig. 3 Head vs grid number
3 计算结果分析

3.1 流道出口流动均匀性分析

 图 4 流道出口的速度云图 Fig. 4 The velocity cloud of duct outlet

 图 5 流道出口的速度分布等值线图 Fig. 5 The velocity distribution contour map of duct outlet
3.2 进水流道内流场分析

 图 6 不同倾角的流道熵值分布云图 Fig. 6 The entropy value distribution of different duct angle
3.3 流道进口附近流场分析

 图 7 流道进口总压分布云图 Fig. 7 The total pressure distribution of duct inlet

 图 8 进水流道唇部总压 Fig. 8 The total pressure distribution of the duct lips

 图 9 距进水口100 mm处总压分布 Fig. 9 The total pressure distribution from the duct inlet to 100 mm
4 结　语

1）随着流道倾角的增大，流道出口流场均匀性变差，在流道倾角达到47°时流道内流场的不均匀性增大，这不利于流道性能的改善。

2）在流道出口存在 2 个对称的分离螺旋点，随着流道倾角的增大，在流道下沿的流体流速增大且向两侧流动，更容易发生分离现象，流体熵值损失也变大，当流道倾角增大到47°时，流道内进口附近的熵值损失还较小，但是在靠近流道出口的熵值损失较为明显，这增加了流体的能量损失。

3）流场随着流体的升高在靠近流道前半部位置分布渐均匀，而在流道背部位置逐渐出现环形高压区，且随着流道倾角的增加，流道背部出现的环形高压区压力越高，这样在流道背部由于压力差引起的流动分离越容易发生，这不利于改进流道的整体性能。

 [1] 康希宗, 王绍增. 喷水推进器进水流道空化和流动分离的模拟控制研究[J]. 理论与实践, 2013, 33 (3): 20–25. [2] BULTEN N. Review of thrust prediction method based on momentum balance for ducted propellers and waterjets[C]// Houston: Proceedings of FEDSM 2005 ASME, 2005. [3] 魏应三, 王永生, 丁江明. 喷水推进器进水流道倾角与流动性能关系研究[J]. 舰船科学技术, 2009, 31 (4): 49–52. Wei Y S, Wang Y S, Ding J M. Research on effect of inclination on characteristics of waterjet duct[J]. Ship Science and Technology, 2009, 31 (4): 49–52. [4] 常书平, 王永生, 庞之洋, 等. 喷水推进器进水流道内流场数值模拟与分析[J]. 武汉理工大学学报: 交通科学与工程版, 2010, 34 (1): 47–52. [5] 丁江明, 王永生. 喷水推进器进水流道参数化设计方法[J]. 哈尔滨工程大学学报, 2011, 32 (4): 423–426. Ding J M, Wang Y S. Research on the parametric design of an inlet duct found in a marine waterjet[J]. Journal of Harbin Engineering University, 2011, 32 (4): 423–426. [6] 王福军. 计算流体动力学分析——CFD软件原理与应用[M]. 北京: 清华大学出版社, 2004. [7] 罗忠, 陈志坚, 孙春生. 喷水推进流道格栅的涡激效应与结构强度[J]. 船舶工程, 2007, 29 (8): 19–21. [8] TERWISGA V. Waterjet propulsive performance prediction- waterjet inlet duct, pump loop and waterjet system tests and extrapolation[C/CD]//Final Recommendations of the Specialist Committee on Validation of Waterjet Test Procedures to the 24th ITTC. Edinburgh, UK: ITTC, 2005. [9] 魏应三, 王永生. 喷水推进器进水流道不均匀度统一描述[J]. 武汉理工大学学报, 2009, 31 (8): 159–163. [10] 刘润闻, 黄国富. 入口唇角对喷水管道流动性能影响的数值分析[J]. 中国造船, 2011, 52 (1): 39–43. Liu R W, Huang G F. Numerical Study on Effect of Inlet Lip on Hydrodynamics for Waterjet Propulsion[J]. Shipbuilding of China, 2011, 52 (1): 39–43.