﻿ 喷水推进进口流道倾斜角对其效率影响分析
 舰船科学技术  2016, Vol. 38 Issue (3): 55-58,96 PDF

1. 上海交通大学海洋工程国家重点实验室, 上海 200011;
2. 中国船舶及海洋工程设计研究院, 上海 200011;
3. 喷水推进重点实验室, 上海 200011

Analysis about affect of inclination angle on the efficiency of the waterjet propulsion inlet duct
JI Guo-rui1, 2, CAI You-lin2, 3, LI Ning2, 3, YIN Xiao-hui2, 3, YU yu2, 3
1. State Key Laboratory of Ocean Engineering, Shanghai Jiaotong University, Shanghai 200011, China;
2. Marine Design and Research Institute of China, Shanghai 200011, China;
3. Key Laboratory of Waterjet Propulsion, Shanghai 200011, China
Abstract: There are many feature parameters describing waterjet propulsion inlet duct and these parameters are related. When some dimensionischanged, the other ones are altered along with that. This paper concludes the relationship of these parameters through derivation. On the basis of that, in the condition that the inletduct feature diameter D, the height of duct H, the overall length of duct L are given, taking the duct inclination angle as variable, it designs and establishes models to research the relationship between inlet duct efficiency and inclinationangle through CFD technology. The result reveals that the inlet duct efficiency decreases with the rising of the inletduct inclination angle. However the decrease value is little. So to some extends, the inlet duct inclination angle has little affect on the inlet flow duct efficiency. This conclusion has great guiding significance in designing inlet duct.
Key words: Waterjet propulsion    Inlet duct    Inclination angle    Efficiency
0 引言

1 进口流道倾斜角与其他特征参数之间的关系

 图 1 进口流道特征尺寸示意图 Fig. 1 The feature dimensions of inlet duct

 ${L_1} + {R_1} \cdot \sin \alpha + {L_2} \cdot \sin \alpha + {R_2} \cdot \sin \alpha = L \text{，}$ (1)
 图 2 进口流道背部尺寸示意图 Fig. 2 The back dimensions of inlet duct

 ${R_{1}}\cdot \left( 1-\cos \alpha \right)+{L_{2}}\cdot \sin \alpha + {R_{2}}\cdot \left( 1-\cos \alpha \right)\ =H+\frac{D}{2} \text{，}$ (2)

 $\left( {R_{1}}\!-\!D \right)\cdot \left( 1\!-\!\cos \alpha \right)\!+\!{L_{3}}\cdot \sin \alpha \! +\! {R_{3}}\cdot \cos {\alpha{α}} +h\ =H-\!\frac{D}{2}\text{，}$ (3)
 图 3 唇口尺寸示意图 Fig. 3 The lip dimensions of inlet duct

 ${{AB}^{2}}+{{BC}^{2}}={{AC}^{2}} \text{，}$ (4)
 图 4 唇口局部示意图 Fig. 4 The local dimensions of lip

 $AC={{R}_{4}}-{{R}_{3}}\text{，}$ (5)
 $AB={{R}_{4}}-h\text{；}$ (6)

 $\begin{array}{l} BC = {L_3}\cos \alpha + ({R_1} - D - {R_3}){\rm{sin}}\alpha - \ (L - L{}_0 - {L_1})\text{。} \end{array}$ (7)

 $\begin{array}{l} {({R_4} - h)^2} + ({L_3} \cdot \cos \alpha + ({R_1} - D - {R_3}){\rm{\cdot}}{\rm{sin}}\alpha - \ (L - {L_0} - {L_1}){)^2} = {({R_4} - {R_4})^2}\text{。} \end{array}$ (8)

 \begin{aligned} {L_3} \! - \! {L_2} \! = \! - \frac{1}{{{\rm{sin}}\alpha }}D \! +\! {h + }{R_3}{\rm{cos}}\alpha \! - \! ({R_2} + D) (1 \! - \! {\rm{cos}}\alpha ) \text{，} \end{aligned} (9)

 \begin{aligned} ( - \frac{{{\rm{cos}}\alpha }}{{{\rm{sin}}\alpha }}(D & + {H + }{R_3} \cdot {\rm{cos}}\alpha - ({R_2} + D)(1 - {\rm{cos}}\alpha )-\\ & (D + {R_3}){\rm{sin}}\alpha - {R_2} \cdot {\rm{sin}}\alpha + {L_0}{)^2}=\\ & {({R_4} - {R_3})^2} - {({R_4} - h)^2} \text{。} \end{aligned} (10)

2 进口流道效率衡量准则

 $\eta = \frac{{{{\rm{E}}_{{\rm{in}}}}}}{{{{\rm{E}}_{{\rm{out}}}}}} \times 100\% \text{，}$ (11)

 $E = \int {[\frac{1}{2}\rho {u^2} + (p - {p_0}) - \rho gx]} {\rm{d}}Q \text{。}$ (12)

3 实例计算

1）L1L2L3R3； 2）L1L2L3R2；

3）L1L2L3R4； 4）L1L2L3h；

5）L1L2L3L0

3.1 网格划分

3.2 湍流模型

3.3 边界条件

 图 5 进口流道三维模型及流域 Fig. 5 The 3D model and flow field of inlet duct

 图 6 进口流道网格 Fig. 6 The mesh of inlet duct
3.4 效率变化

 图 7 不同流道倾斜角下流道效率 Fig. 7 The efficiency of inlet duct at different titling angle

4 结语

1）第 4 个参数选为 R2 时，流道效率随流道倾斜角的下降最小。

2）当流道倾斜角从 22° ~ 27°之间改变时，第4个参数选取不同，进口流道效率变化规律也不同，但流道效率都在23°时达到最大，当流道倾斜角从23°~27°变化时，流道效率整体上都会随着倾斜角的增加而减小。

3）流道倾斜角从22°~27°改变时，无论第4个参数选哪一个，各倾斜角对应的流道效率最大差别不超过2%，所以在实际的设计中，如果流道倾斜角不能取的太小，可以适当增加倾斜角而不会对流道效率有太大影响，有利于控制装置长度与重量。

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