﻿ 90°弯管对潜艇高压气管路沿程压力损失的影响分析
 舰船科学技术  2020, Vol. 42 Issue (8): 93-97    DOI: 10.3404/j.issn.1672-7649.2020.08.017 PDF
90°弯管对潜艇高压气管路沿程压力损失的影响分析

1. 海军潜艇学院，山东 青岛 266199;
2. 中国人民解放军92196部队，山东 青岛 266011

Analysis of the influence of 90° elbow on the pressure loss along the submarine high pressure gas pipe
ZHANG Jian-hua1, HU Kun1, HUANG Hai-feng1, WEI Jing-guang2
1. Navy Submarine Academy, Qingdao 266199, China;
2. No. 92196 Unit of PLA, Qingdao 266011, China
Abstract: For the problem of the pressure drop loss and the equivalent length calculaiton of elbows in submarine highpressure pipelines, the flow processes of ultra-high pressure gas in 90° elbows were numerically simulated by the way of CFD. The inner flow area was meshed with structured hexahedral grid, and by means of the numerical solution to deal with the RANS equations closed by RNG k-ε turbulence model, the flow field characteristics inside the pipe was studied, and the pressure distribution and velocity distribution inside the elbows were obtained, in addition, the generation and development of secondary flow were captured, and the calculated results are consistent with the numerical simulaiton and model experiment results carried out by other scholars. Simulation results show that the total pressure loss of the pipe will be increased greatly due to the partial pressure loss caused by elbows, and then the emergency blowing efficiency of the high pressure gas will be effected, so it must be paid attention to during the design and build period, besides, the feasibility and availability of simulating the flow characteristics of the ultra-high pressure gas inside the elbows by RNG k-ε turbulence model were verified.
Key words: 90° elbow     high pressure gas     pressure loss     submarine     secondary flow
0 引　言

1 湍流模型

 $\frac{{\partial (\rho k)}}{{\partial t}} + \frac{{\partial \left( {\rho k{u_i}} \right)}}{{\partial {x_i}}} = \frac{\partial }{{\partial {x_j}}}\left[ {{\alpha _k}{\mu _{eff}}\frac{{\partial k}}{{\partial {x_j}}}} \right] + {G_k} + {G_b} - \rho \varepsilon - {Y_M}{\text{，}}$ (1)
 $\begin{split}\frac{{\partial (\rho \varepsilon )}}{{\partial t}} +& \frac{{\partial (\rho \varepsilon {u_i})}}{{\partial {x_i}}} = \frac{\partial }{{\partial {x_j}}}\left[ {\left( {{\alpha _\varepsilon }{\mu _{eff}}} \right)\frac{{\partial \varepsilon }}{{\partial {x_j}}}} \right] + \\ &{C_{1\varepsilon }}\frac{\varepsilon }{k}({G_k} +{C_{3\varepsilon }}{G_b}) - C_{2\varepsilon }^*\rho \frac{{{\varepsilon ^2}}}{k}{\text{。}}\end{split}$ (2)

2 实验方案

 图 1 管路及弯头尺寸参数 Fig. 1 Dimensions of the pipe and elbow
3 数值求解过程 3.1 边界条件与数值方法

3.2 离散网格

 图 2 弯管部分网格划分 Fig. 2 Mesh of the elbow

 图 3 直管部分网格划分 Fig. 3 Mesh of the straight pipe
4 计算结果与分析

4.1 弯管及其附近压力分布规律

 图 4 对称面上等压线分布 Fig. 4 Isobaric distribution of the symmetry plane

 图 5 弯管不同极角截面上的压力分布云图 Fig. 5 Pressure distribution contours of different polar-angle sections of the elbow

 图 6 弯头外侧壁面上压力系数随极角的变化关系[12] Fig. 6 Pressure factor versus polar-angle on the outer wall

4.2 弯管及其附近速度分布规律

 图 7 弯管对称面速度分布及速度矢量图 Fig. 7 Velocity distribution and vectorgraph of the elbow symmetry plane

 图 8 弯管不同极角截面上的速度分布云图 Fig. 8 Velocity distribution contours of different polar-angle sections of the elbow
4.3 二次流现象

 图 9 弯管横截面上二次流图像 Fig. 9 Secondary flow pictures on the sections of elbow
5 结　语

1）在管路总长度不变情况下，弯管引起的局部压力降会较大程度增加管路总的沿程压力损失，在文中所述压力条件下，一个弯管所产生的局部压降约为0.2 MPa，其当量长度约为0.25 m。

2）弯头内沿流动方向上的压力分布规律为内侧压力先减小后增大，外侧压力先增大后减小，但外侧压力始终大于内侧压力；速度分布规律为内侧速度先增大后减小，外侧速度先减小后增大，且在弯头终端截面，其内侧会形成低速区。

3）流体进入弯头后，由于流场逆压梯度和分子黏性的共同作用，会有二次流产生，从而导致弯管内横截面上发生动能和能量的交换。

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